//! Configuration loading and defaults for DeepSeek TUI.

use std::collections::HashMap;
use std::fmt::Write;
use std::fs;
use std::path::{Path, PathBuf};

use anyhow::{Context, Result};
use serde::Deserialize;
use serde_json::json;

use crate::audit::log_sensitive_event;
use crate::features::{Features, FeaturesToml, is_known_feature_key};
use crate::hooks::HooksConfig;

pub const DEFAULT_MAX_SUBAGENTS: usize = 5;
pub const MAX_SUBAGENTS: usize = 20;
pub const DEFAULT_TEXT_MODEL: &str = "deepseek-v4-pro";
pub const DEFAULT_NVIDIA_NIM_MODEL: &str = "deepseek-ai/deepseek-v4-pro";
pub const DEFAULT_NVIDIA_NIM_FLASH_MODEL: &str = "deepseek-ai/deepseek-v4-flash";
pub const DEFAULT_NVIDIA_NIM_BASE_URL: &str = "https://integrate.api.nvidia.com/v1";
const API_KEYRING_SENTINEL: &str = "__KEYRING__";
pub const COMMON_DEEPSEEK_MODELS: &[&str] = &[
    "deepseek-v4-pro",
    "deepseek-v4-flash",
    "deepseek-ai/deepseek-v4-pro",
    "deepseek-ai/deepseek-v4-flash",
];

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ApiProvider {
    Deepseek,
    NvidiaNim,
}

impl ApiProvider {
    #[must_use]
    pub fn parse(value: &str) -> Option<Self> {
        match value.trim().to_ascii_lowercase().as_str() {
            "deepseek" | "deep-seek" => Some(Self::Deepseek),
            "nvidia" | "nvidia-nim" | "nvidia_nim" | "nim" => Some(Self::NvidiaNim),
            _ => None,
        }
    }

    #[must_use]
    pub fn as_str(self) -> &'static str {
        match self {
            Self::Deepseek => "deepseek",
            Self::NvidiaNim => "nvidia-nim",
        }
    }
}

/// Canonicalize common model aliases to stable DeepSeek IDs.
///
/// Legacy `deepseek-chat` / `deepseek-reasoner` remain silent aliases for the
/// current fast V4 model.
#[must_use]
pub fn canonical_model_name(model: &str) -> Option<&'static str> {
    match model.trim().to_ascii_lowercase().as_str() {
        "deepseek-v4-pro" | "deepseek-v4pro" => Some("deepseek-v4-pro"),
        "deepseek-v4-flash" | "deepseek-v4flash" => Some("deepseek-v4-flash"),
        "deepseek-chat" | "deepseek-reasoner" | "deepseek-r1" | "deepseek-v3" | "deepseek-v3.2" => {
            Some("deepseek-v4-flash")
        }
        _ => None,
    }
}

/// Normalize a configured/runtime model name.
///
/// Accepts known aliases plus any valid `deepseek*` model ID so future
/// DeepSeek releases work without code changes.
#[must_use]
pub fn normalize_model_name(model: &str) -> Option<String> {
    let trimmed = model.trim();
    if trimmed.is_empty() {
        return None;
    }
    if let Some(canonical) = canonical_model_name(trimmed) {
        return Some(canonical.to_string());
    }

    let normalized = trimmed.to_ascii_lowercase();
    if !normalized.starts_with("deepseek") {
        return None;
    }

    if normalized.chars().all(|ch| {
        ch.is_ascii_lowercase() || ch.is_ascii_digit() || matches!(ch, '-' | '_' | '.' | ':' | '/')
    }) {
        return Some(normalized);
    }

    None
}

// === Types ===

/// Raw retry configuration loaded from config files.
#[derive(Debug, Clone, Deserialize)]
pub struct RetryConfig {
    pub enabled: Option<bool>,
    pub max_retries: Option<u32>,
    pub initial_delay: Option<f64>,
    pub max_delay: Option<f64>,
    pub exponential_base: Option<f64>,
}

/// UI configuration loaded from config files.
#[derive(Debug, Clone, Deserialize, Default)]
pub struct TuiConfig {
    pub alternate_screen: Option<String>,
    pub mouse_capture: Option<bool>,
}

/// Resolved retry policy with defaults applied.
#[derive(Debug, Clone)]
pub struct RetryPolicy {
    pub enabled: bool,
    pub max_retries: u32,
    pub initial_delay: f64,
    pub max_delay: f64,
    pub exponential_base: f64,
}

/// Capacity-controller config loaded from config files/environment.
#[derive(Debug, Clone, Deserialize)]
pub struct CapacityConfig {
    pub enabled: Option<bool>,
    pub low_risk_max: Option<f64>,
    pub medium_risk_max: Option<f64>,
    pub severe_min_slack: Option<f64>,
    pub severe_violation_ratio: Option<f64>,
    pub refresh_cooldown_turns: Option<u64>,
    pub replan_cooldown_turns: Option<u64>,
    pub max_replay_per_turn: Option<usize>,
    pub min_turns_before_guardrail: Option<u64>,
    pub profile_window: Option<usize>,
    pub deepseek_v3_2_chat_prior: Option<f64>,
    pub deepseek_v3_2_reasoner_prior: Option<f64>,
    pub deepseek_v4_pro_prior: Option<f64>,
    pub deepseek_v4_flash_prior: Option<f64>,
    pub fallback_default_prior: Option<f64>,
}

impl RetryPolicy {
    /// Compute the backoff delay for a retry attempt.
    #[must_use]
    #[allow(dead_code)] // used by runtime_api; will be wired into client retry loop
    pub fn delay_for_attempt(&self, attempt: u32) -> std::time::Duration {
        let exponent = i32::try_from(attempt).unwrap_or(i32::MAX);
        let delay = self.initial_delay * self.exponential_base.powi(exponent);
        let delay = delay.min(self.max_delay);
        // Clamp to a sane range to guard against NaN/negative from misconfigured values
        let delay = delay.clamp(0.0, 300.0);
        std::time::Duration::from_secs_f64(delay)
    }
}

/// Resolved CLI configuration, including defaults and environment overrides.
#[derive(Debug, Clone, Default, Deserialize)]
pub struct Config {
    pub provider: Option<String>,
    pub api_key: Option<String>,
    pub base_url: Option<String>,
    pub default_text_model: Option<String>,
    /// DeepSeek reasoning-effort tier: `"off" | "low" | "medium" | "high" | "max"`.
    /// Defaults to `"max"` at runtime if unset.
    pub reasoning_effort: Option<String>,
    pub tools_file: Option<String>,
    pub skills_dir: Option<String>,
    pub mcp_config_path: Option<String>,
    pub notes_path: Option<String>,
    pub memory_path: Option<String>,
    pub allow_shell: Option<bool>,
    pub approval_policy: Option<String>,
    pub sandbox_mode: Option<String>,
    pub managed_config_path: Option<String>,
    pub requirements_path: Option<String>,
    pub max_subagents: Option<usize>,
    pub retry: Option<RetryConfig>,
    pub capacity: Option<CapacityConfig>,
    pub features: Option<FeaturesToml>,

    /// TUI configuration (alternate screen, etc.)
    pub tui: Option<TuiConfig>,

    /// Lifecycle hooks configuration
    #[serde(default)]
    pub hooks: Option<HooksConfig>,

    /// Provider-specific credentials and defaults shared with the `deepseek` facade.
    #[serde(default)]
    pub providers: Option<ProvidersConfig>,
}

#[derive(Debug, Clone, Default, Deserialize)]
pub struct ProviderConfig {
    pub api_key: Option<String>,
    pub base_url: Option<String>,
    pub model: Option<String>,
}

#[derive(Debug, Clone, Default, Deserialize)]
pub struct ProvidersConfig {
    #[serde(default)]
    pub deepseek: ProviderConfig,
    #[serde(default)]
    pub nvidia_nim: ProviderConfig,
}

#[derive(Debug, Clone, Deserialize, Default)]
struct ConfigFile {
    #[serde(flatten)]
    base: Config,
    profiles: Option<HashMap<String, Config>>,
}

#[derive(Debug, Clone, Deserialize, Default)]
struct RequirementsFile {
    #[serde(default)]
    allowed_approval_policies: Vec<String>,
    #[serde(default)]
    allowed_sandbox_modes: Vec<String>,
}

// === Config Loading ===

impl Config {
    /// Load configuration from disk and merge with environment overrides.
    ///
    /// # Examples
    ///
    /// ```ignore
    /// # use crate::config::Config;
    /// let config = Config::load(None, None)?;
    /// # Ok::<(), anyhow::Error>(())
    /// ```
    pub fn load(path: Option<PathBuf>, profile: Option<&str>) -> Result<Self> {
        let path = resolve_load_config_path(path);
        let mut config = if let Some(path) = path.as_ref() {
            if path.exists() {
                let contents = fs::read_to_string(path)
                    .with_context(|| format!("Failed to read config file: {}", path.display()))?;
                let parsed: ConfigFile = toml::from_str(&contents)
                    .with_context(|| format!("Failed to parse config file: {}", path.display()))?;
                apply_profile(parsed, profile)?
            } else {
                Config::default()
            }
        } else {
            Config::default()
        };

        apply_env_overrides(&mut config);
        apply_managed_overrides(&mut config)?;
        apply_requirements(&mut config)?;
        normalize_model_config(&mut config);
        config.validate()?;
        Ok(config)
    }

    /// Validate that critical config fields are present.
    pub fn validate(&self) -> Result<()> {
        if let Some(provider) = self.provider.as_deref()
            && ApiProvider::parse(provider).is_none()
        {
            anyhow::bail!("Invalid provider '{provider}': expected deepseek or nvidia-nim.");
        }
        if let Some(ref key) = self.api_key
            && key.trim().is_empty()
        {
            anyhow::bail!("api_key cannot be empty string");
        }
        if let Some(features) = &self.features {
            for key in features.entries.keys() {
                if !is_known_feature_key(key) {
                    anyhow::bail!("Unknown feature flag: {key}");
                }
            }
        }
        if let Some(model) = self.default_text_model.as_deref()
            && normalize_model_name(model).is_none()
        {
            anyhow::bail!(
                "Invalid default_text_model '{model}': expected a DeepSeek model ID (for example: deepseek-v4-pro, deepseek-v4-flash, deepseek-ai/deepseek-v4-pro)."
            );
        }
        if let Some(policy) = self.approval_policy.as_deref() {
            let normalized = policy.trim().to_ascii_lowercase();
            if !matches!(
                normalized.as_str(),
                "on-request" | "untrusted" | "never" | "auto" | "suggest"
            ) {
                anyhow::bail!(
                    "Invalid approval_policy '{policy}': expected on-request, untrusted, never, auto, or suggest."
                );
            }
        }
        if let Some(mode) = self.sandbox_mode.as_deref() {
            let normalized = mode.trim().to_ascii_lowercase();
            if !matches!(
                normalized.as_str(),
                "read-only" | "workspace-write" | "danger-full-access" | "external-sandbox"
            ) {
                anyhow::bail!(
                    "Invalid sandbox_mode '{mode}': expected read-only, workspace-write, danger-full-access, or external-sandbox."
                );
            }
        }
        if let Some(tui) = &self.tui
            && let Some(mode) = tui.alternate_screen.as_deref()
        {
            let mode = mode.to_ascii_lowercase();
            if !matches!(mode.as_str(), "auto" | "always" | "never") {
                anyhow::bail!(
                    "Invalid tui.alternate_screen '{mode}': expected auto, always, or never."
                );
            }
        }
        if let Some(capacity) = &self.capacity {
            if let Some(v) = capacity.low_risk_max
                && !(0.0..=1.0).contains(&v)
            {
                anyhow::bail!(
                    "Invalid capacity.low_risk_max '{v}': expected a value in [0.0, 1.0]."
                );
            }
            if let Some(v) = capacity.medium_risk_max
                && !(0.0..=1.0).contains(&v)
            {
                anyhow::bail!(
                    "Invalid capacity.medium_risk_max '{v}': expected a value in [0.0, 1.0]."
                );
            }
            if let (Some(low), Some(medium)) = (capacity.low_risk_max, capacity.medium_risk_max)
                && low > medium
            {
                anyhow::bail!(
                    "Invalid capacity thresholds: low_risk_max ({low}) must be <= medium_risk_max ({medium})."
                );
            }
            if let Some(v) = capacity.severe_violation_ratio
                && !(0.0..=1.0).contains(&v)
            {
                anyhow::bail!(
                    "Invalid capacity.severe_violation_ratio '{v}': expected a value in [0.0, 1.0]."
                );
            }
        }
        Ok(())
    }

    #[must_use]
    pub fn api_provider(&self) -> ApiProvider {
        self.provider
            .as_deref()
            .and_then(ApiProvider::parse)
            .unwrap_or_else(|| {
                self.base_url
                    .as_deref()
                    .filter(|base| base.contains("integrate.api.nvidia.com"))
                    .map(|_| ApiProvider::NvidiaNim)
                    .unwrap_or(ApiProvider::Deepseek)
            })
    }

    fn provider_config_for(&self, provider: ApiProvider) -> Option<&ProviderConfig> {
        let providers = self.providers.as_ref()?;
        Some(match provider {
            ApiProvider::Deepseek => &providers.deepseek,
            ApiProvider::NvidiaNim => &providers.nvidia_nim,
        })
    }

    fn provider_config(&self) -> Option<&ProviderConfig> {
        self.provider_config_for(self.api_provider())
    }

    #[must_use]
    pub fn default_model(&self) -> String {
        let provider = self.api_provider();
        if let Some(model) = self
            .provider_config()
            .and_then(|provider| provider.model.as_deref())
            && let Some(normalized) = normalize_model_for_provider(provider, model)
        {
            return normalized;
        }
        if let Some(model) = self.default_text_model.as_deref()
            && let Some(normalized) = normalize_model_name(model)
        {
            return model_for_provider(provider, normalized);
        }

        match provider {
            ApiProvider::Deepseek => DEFAULT_TEXT_MODEL,
            ApiProvider::NvidiaNim => DEFAULT_NVIDIA_NIM_MODEL,
        }
        .to_string()
    }

    /// Return the configured API base URL (normalized).
    #[must_use]
    pub fn deepseek_base_url(&self) -> String {
        let provider = self.api_provider();
        let provider_base = self
            .provider_config_for(provider)
            .and_then(|provider| provider.base_url.clone());
        let root_base = match provider {
            ApiProvider::Deepseek => self.base_url.clone(),
            ApiProvider::NvidiaNim => self
                .base_url
                .as_ref()
                .filter(|base| base.contains("integrate.api.nvidia.com"))
                .cloned(),
        };
        let base = provider_base.or(root_base).unwrap_or_else(|| {
            match provider {
                ApiProvider::Deepseek => "https://api.deepseek.com",
                ApiProvider::NvidiaNim => DEFAULT_NVIDIA_NIM_BASE_URL,
            }
            .to_string()
        });
        normalize_base_url(&base)
    }

    /// Read the API key from config/environment.
    pub fn deepseek_api_key(&self) -> Result<String> {
        let provider = self.api_provider();

        match provider {
            ApiProvider::Deepseek => {
                if let Ok(key) = std::env::var("DEEPSEEK_API_KEY")
                    && !key.trim().is_empty()
                {
                    return Ok(key);
                }
            }
            ApiProvider::NvidiaNim => {
                for name in ["NVIDIA_API_KEY", "NVIDIA_NIM_API_KEY", "DEEPSEEK_API_KEY"] {
                    if let Ok(key) = std::env::var(name)
                        && !key.trim().is_empty()
                    {
                        return Ok(key);
                    }
                }
            }
        }

        // Then check config file
        if let Some(configured) = self
            .provider_config_for(provider)
            .and_then(|provider| provider.api_key.clone())
            && !configured.trim().is_empty()
        {
            return Ok(configured);
        }

        if let Some(configured) = self.api_key.clone()
            && !configured.trim().is_empty()
            && configured != API_KEYRING_SENTINEL
        {
            return Ok(configured);
        }

        match provider {
            ApiProvider::Deepseek => anyhow::bail!(
                "DeepSeek API key not found. Set it using one of these methods:\n\
                 1. Set DEEPSEEK_API_KEY environment variable (recommended)\n\
                 2. Run 'deepseek login' to save to ~/.deepseek/config.toml\n\
                 3. Add 'api_key = \"your-key\"' to ~/.deepseek/config.toml"
            ),
            ApiProvider::NvidiaNim => anyhow::bail!(
                "NVIDIA NIM API key not found. Set NVIDIA_API_KEY, NVIDIA_NIM_API_KEY, \
                 or save api_key in ~/.deepseek/config.toml with provider = \"nvidia-nim\"."
            ),
        }
    }

    /// Resolve the skills directory path.
    #[must_use]
    pub fn skills_dir(&self) -> PathBuf {
        self.skills_dir
            .as_deref()
            .map(expand_path)
            .or_else(default_skills_dir)
            .unwrap_or_else(|| PathBuf::from("./skills"))
    }

    /// Resolve the MCP config path.
    #[must_use]
    pub fn mcp_config_path(&self) -> PathBuf {
        self.mcp_config_path
            .as_deref()
            .map(expand_path)
            .or_else(default_mcp_config_path)
            .unwrap_or_else(|| PathBuf::from("./mcp.json"))
    }

    /// Resolve the notes file path.
    #[must_use]
    pub fn notes_path(&self) -> PathBuf {
        self.notes_path
            .as_deref()
            .map(expand_path)
            .or_else(default_notes_path)
            .unwrap_or_else(|| PathBuf::from("./notes.txt"))
    }

    /// Resolve the memory file path.
    #[must_use]
    pub fn memory_path(&self) -> PathBuf {
        self.memory_path
            .as_deref()
            .map(expand_path)
            .or_else(default_memory_path)
            .unwrap_or_else(|| PathBuf::from("./memory.md"))
    }

    /// Return whether shell execution is allowed.
    #[must_use]
    pub fn allow_shell(&self) -> bool {
        self.allow_shell.unwrap_or(true)
    }

    /// Return the maximum number of concurrent sub-agents.
    #[must_use]
    pub fn max_subagents(&self) -> usize {
        self.max_subagents
            .unwrap_or(DEFAULT_MAX_SUBAGENTS)
            .clamp(1, MAX_SUBAGENTS)
    }

    /// Return the configured DeepSeek reasoning-effort tier, if any.
    #[must_use]
    pub fn reasoning_effort(&self) -> Option<&str> {
        self.reasoning_effort.as_deref()
    }

    /// Get hooks configuration, returning default if not configured.
    pub fn hooks_config(&self) -> HooksConfig {
        self.hooks.clone().unwrap_or_default()
    }

    /// Resolve enabled features from defaults and config entries.
    #[must_use]
    pub fn features(&self) -> Features {
        let mut features = Features::with_defaults();
        if let Some(table) = &self.features {
            features.apply_map(&table.entries);
        }
        features
    }

    /// Override a feature flag in memory (used by CLI overrides).
    pub fn set_feature(&mut self, key: &str, enabled: bool) -> Result<()> {
        if !is_known_feature_key(key) {
            anyhow::bail!("Unknown feature flag: {key}");
        }
        let table = self.features.get_or_insert_with(FeaturesToml::default);
        table.entries.insert(key.to_string(), enabled);
        Ok(())
    }

    /// Resolve the effective retry policy with defaults applied.
    #[must_use]
    pub fn retry_policy(&self) -> RetryPolicy {
        let defaults = RetryPolicy {
            enabled: true,
            max_retries: 3,
            initial_delay: 1.0,
            max_delay: 60.0,
            exponential_base: 2.0,
        };

        let Some(cfg) = &self.retry else {
            return defaults;
        };

        RetryPolicy {
            enabled: cfg.enabled.unwrap_or(defaults.enabled),
            max_retries: cfg.max_retries.unwrap_or(defaults.max_retries),
            initial_delay: cfg.initial_delay.unwrap_or(defaults.initial_delay),
            max_delay: cfg.max_delay.unwrap_or(defaults.max_delay),
            exponential_base: cfg.exponential_base.unwrap_or(defaults.exponential_base),
        }
    }
}

// === Defaults ===

fn default_config_path() -> Option<PathBuf> {
    env_config_path().or_else(home_config_path)
}

fn effective_home_dir() -> Option<PathBuf> {
    if let Some(path) = std::env::var_os("HOME") {
        let path = PathBuf::from(path);
        if !path.as_os_str().is_empty() {
            return Some(path);
        }
    }

    if let Some(path) = std::env::var_os("USERPROFILE") {
        let path = PathBuf::from(path);
        if !path.as_os_str().is_empty() {
            return Some(path);
        }
    }

    #[cfg(windows)]
    {
        if let (Some(drive), Some(homepath)) =
            (std::env::var_os("HOMEDRIVE"), std::env::var_os("HOMEPATH"))
        {
            let mut path = PathBuf::from(drive);
            path.push(homepath);
            if !path.as_os_str().is_empty() {
                return Some(path);
            }
        }
    }

    dirs::home_dir()
}

fn home_config_path() -> Option<PathBuf> {
    effective_home_dir().map(|home| home.join(".deepseek").join("config.toml"))
}

fn env_config_path() -> Option<PathBuf> {
    if let Ok(path) = std::env::var("DEEPSEEK_CONFIG_PATH") {
        let trimmed = path.trim();
        if !trimmed.is_empty() {
            return Some(expand_path(trimmed));
        }
    }
    None
}

fn expand_pathbuf(path: PathBuf) -> PathBuf {
    if let Some(raw) = path.to_str() {
        return expand_path(raw);
    }
    path
}

fn resolve_load_config_path(path: Option<PathBuf>) -> Option<PathBuf> {
    if let Some(path) = path {
        return Some(expand_pathbuf(path));
    }

    if let Some(path) = env_config_path() {
        if path.exists() {
            return Some(path);
        }

        if let Some(home_path) = home_config_path()
            && home_path.exists()
        {
            return Some(home_path);
        }

        return Some(path);
    }

    home_config_path()
}

fn default_managed_config_path() -> Option<PathBuf> {
    #[cfg(unix)]
    {
        Some(PathBuf::from("/etc/deepseek/managed_config.toml"))
    }
    #[cfg(not(unix))]
    {
        effective_home_dir().map(|home| home.join(".deepseek").join("managed_config.toml"))
    }
}

fn default_requirements_path() -> Option<PathBuf> {
    #[cfg(unix)]
    {
        Some(PathBuf::from("/etc/deepseek/requirements.toml"))
    }
    #[cfg(not(unix))]
    {
        effective_home_dir().map(|home| home.join(".deepseek").join("requirements.toml"))
    }
}

pub(crate) fn expand_path(path: &str) -> PathBuf {
    if let Some(stripped) = path.strip_prefix('~')
        && (stripped.is_empty() || stripped.starts_with('/') || stripped.starts_with('\\'))
        && let Some(mut home) = effective_home_dir()
    {
        let suffix = stripped.trim_start_matches(['/', '\\']);
        if !suffix.is_empty() {
            home.push(suffix);
        }
        return home;
    }

    let expanded = shellexpand::tilde(path);
    PathBuf::from(expanded.as_ref())
}

fn default_skills_dir() -> Option<PathBuf> {
    effective_home_dir().map(|home| home.join(".deepseek").join("skills"))
}

fn default_mcp_config_path() -> Option<PathBuf> {
    effective_home_dir().map(|home| home.join(".deepseek").join("mcp.json"))
}

fn default_notes_path() -> Option<PathBuf> {
    effective_home_dir().map(|home| home.join(".deepseek").join("notes.txt"))
}

fn default_memory_path() -> Option<PathBuf> {
    effective_home_dir().map(|home| home.join(".deepseek").join("memory.md"))
}

// === Environment Overrides ===

fn apply_env_overrides(config: &mut Config) {
    if let Ok(value) = std::env::var("DEEPSEEK_PROVIDER") {
        config.provider = Some(value);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_API_KEY")
        && !value.trim().is_empty()
    {
        config.api_key = Some(value);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_BASE_URL") {
        if matches!(config.api_provider(), ApiProvider::NvidiaNim) {
            config
                .providers
                .get_or_insert_with(ProvidersConfig::default)
                .nvidia_nim
                .base_url = Some(value);
        } else {
            config.base_url = Some(value);
        }
    }
    if matches!(config.api_provider(), ApiProvider::NvidiaNim)
        && let Ok(value) = std::env::var("NVIDIA_NIM_BASE_URL")
            .or_else(|_| std::env::var("NIM_BASE_URL"))
            .or_else(|_| std::env::var("NVIDIA_BASE_URL"))
    {
        config
            .providers
            .get_or_insert_with(ProvidersConfig::default)
            .nvidia_nim
            .base_url = Some(value);
    }
    if let Ok(value) =
        std::env::var("DEEPSEEK_MODEL").or_else(|_| std::env::var("DEEPSEEK_DEFAULT_TEXT_MODEL"))
    {
        config.default_text_model = Some(value);
    }
    if matches!(config.api_provider(), ApiProvider::NvidiaNim)
        && let Ok(value) = std::env::var("NVIDIA_NIM_MODEL")
    {
        config.default_text_model = Some(value);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_SKILLS_DIR") {
        config.skills_dir = Some(value);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_MCP_CONFIG") {
        config.mcp_config_path = Some(value);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_NOTES_PATH") {
        config.notes_path = Some(value);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_MEMORY_PATH") {
        config.memory_path = Some(value);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_ALLOW_SHELL") {
        config.allow_shell = Some(value == "1" || value.eq_ignore_ascii_case("true"));
    }
    if let Ok(value) = std::env::var("DEEPSEEK_APPROVAL_POLICY") {
        config.approval_policy = Some(value);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_SANDBOX_MODE") {
        config.sandbox_mode = Some(value);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_MANAGED_CONFIG_PATH") {
        config.managed_config_path = Some(value);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_REQUIREMENTS_PATH") {
        config.requirements_path = Some(value);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_MAX_SUBAGENTS")
        && let Ok(parsed) = value.parse::<usize>()
    {
        config.max_subagents = Some(parsed.clamp(1, MAX_SUBAGENTS));
    }

    let capacity = config.capacity.get_or_insert(CapacityConfig {
        enabled: None,
        low_risk_max: None,
        medium_risk_max: None,
        severe_min_slack: None,
        severe_violation_ratio: None,
        refresh_cooldown_turns: None,
        replan_cooldown_turns: None,
        max_replay_per_turn: None,
        min_turns_before_guardrail: None,
        profile_window: None,
        deepseek_v3_2_chat_prior: None,
        deepseek_v3_2_reasoner_prior: None,
        deepseek_v4_pro_prior: None,
        deepseek_v4_flash_prior: None,
        fallback_default_prior: None,
    });

    if let Ok(value) = std::env::var("DEEPSEEK_CAPACITY_ENABLED") {
        let val = value.trim().to_ascii_lowercase();
        capacity.enabled = Some(matches!(val.as_str(), "1" | "true" | "yes" | "on"));
    }
    if let Ok(value) = std::env::var("DEEPSEEK_CAPACITY_LOW_RISK_MAX")
        && let Ok(parsed) = value.parse::<f64>()
    {
        capacity.low_risk_max = Some(parsed);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_CAPACITY_MEDIUM_RISK_MAX")
        && let Ok(parsed) = value.parse::<f64>()
    {
        capacity.medium_risk_max = Some(parsed);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_CAPACITY_SEVERE_MIN_SLACK")
        && let Ok(parsed) = value.parse::<f64>()
    {
        capacity.severe_min_slack = Some(parsed);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_CAPACITY_SEVERE_VIOLATION_RATIO")
        && let Ok(parsed) = value.parse::<f64>()
    {
        capacity.severe_violation_ratio = Some(parsed);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_CAPACITY_REFRESH_COOLDOWN_TURNS")
        && let Ok(parsed) = value.parse::<u64>()
    {
        capacity.refresh_cooldown_turns = Some(parsed);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_CAPACITY_REPLAN_COOLDOWN_TURNS")
        && let Ok(parsed) = value.parse::<u64>()
    {
        capacity.replan_cooldown_turns = Some(parsed);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_CAPACITY_MAX_REPLAY_PER_TURN")
        && let Ok(parsed) = value.parse::<usize>()
    {
        capacity.max_replay_per_turn = Some(parsed);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_CAPACITY_MIN_TURNS_BEFORE_GUARDRAIL")
        && let Ok(parsed) = value.parse::<u64>()
    {
        capacity.min_turns_before_guardrail = Some(parsed);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_CAPACITY_PROFILE_WINDOW")
        && let Ok(parsed) = value.parse::<usize>()
    {
        capacity.profile_window = Some(parsed);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_CAPACITY_PRIOR_CHAT")
        && let Ok(parsed) = value.parse::<f64>()
    {
        capacity.deepseek_v3_2_chat_prior = Some(parsed);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_CAPACITY_PRIOR_REASONER")
        && let Ok(parsed) = value.parse::<f64>()
    {
        capacity.deepseek_v3_2_reasoner_prior = Some(parsed);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_CAPACITY_PRIOR_V4_PRO")
        && let Ok(parsed) = value.parse::<f64>()
    {
        capacity.deepseek_v4_pro_prior = Some(parsed);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_CAPACITY_PRIOR_V4_FLASH")
        && let Ok(parsed) = value.parse::<f64>()
    {
        capacity.deepseek_v4_flash_prior = Some(parsed);
    }
    if let Ok(value) = std::env::var("DEEPSEEK_CAPACITY_PRIOR_FALLBACK")
        && let Ok(parsed) = value.parse::<f64>()
    {
        capacity.fallback_default_prior = Some(parsed);
    }

    if config.capacity.as_ref().is_some_and(|c| {
        c.enabled.is_none()
            && c.low_risk_max.is_none()
            && c.medium_risk_max.is_none()
            && c.severe_min_slack.is_none()
            && c.severe_violation_ratio.is_none()
            && c.refresh_cooldown_turns.is_none()
            && c.replan_cooldown_turns.is_none()
            && c.max_replay_per_turn.is_none()
            && c.min_turns_before_guardrail.is_none()
            && c.profile_window.is_none()
            && c.deepseek_v3_2_chat_prior.is_none()
            && c.deepseek_v3_2_reasoner_prior.is_none()
            && c.deepseek_v4_pro_prior.is_none()
            && c.deepseek_v4_flash_prior.is_none()
            && c.fallback_default_prior.is_none()
    }) {
        config.capacity = None;
    }
}

fn normalize_model_config(config: &mut Config) {
    if let Some(model) = config.default_text_model.as_deref()
        && let Some(normalized) = normalize_model_for_provider(config.api_provider(), model)
    {
        config.default_text_model = Some(normalized);
    }

    if let Some(providers) = config.providers.as_mut() {
        if let Some(model) = providers.deepseek.model.as_deref()
            && let Some(normalized) = normalize_model_for_provider(ApiProvider::Deepseek, model)
        {
            providers.deepseek.model = Some(normalized);
        }
        if let Some(model) = providers.nvidia_nim.model.as_deref()
            && let Some(normalized) = normalize_model_for_provider(ApiProvider::NvidiaNim, model)
        {
            providers.nvidia_nim.model = Some(normalized);
        }
    }
}

fn normalize_model_for_provider(provider: ApiProvider, model: &str) -> Option<String> {
    normalize_model_name(model).map(|normalized| model_for_provider(provider, normalized))
}

fn model_for_provider(provider: ApiProvider, normalized: String) -> String {
    match (provider, normalized.as_str()) {
        (ApiProvider::NvidiaNim, "deepseek-v4-pro") => DEFAULT_NVIDIA_NIM_MODEL.to_string(),
        (ApiProvider::NvidiaNim, "deepseek-v4-flash") => DEFAULT_NVIDIA_NIM_FLASH_MODEL.to_string(),
        _ => normalized,
    }
}

fn normalize_base_url(base: &str) -> String {
    let trimmed = base.trim_end_matches('/');
    let deepseek_domains = ["api.deepseek.com", "api.deepseeki.com"];
    if deepseek_domains
        .iter()
        .any(|domain| trimmed.contains(domain))
    {
        return trimmed.trim_end_matches("/v1").to_string();
    }
    trimmed.to_string()
}

fn apply_profile(config: ConfigFile, profile: Option<&str>) -> Result<Config> {
    if let Some(profile_name) = profile {
        let profiles = config.profiles.as_ref();
        match profiles.and_then(|profiles| profiles.get(profile_name)) {
            Some(override_cfg) => Ok(merge_config(config.base, override_cfg.clone())),
            None => {
                let available = profiles
                    .map(|profiles| {
                        let mut keys = profiles.keys().cloned().collect::<Vec<_>>();
                        keys.sort();
                        if keys.is_empty() {
                            "none".to_string()
                        } else {
                            keys.join(", ")
                        }
                    })
                    .unwrap_or_else(|| "none".to_string());
                anyhow::bail!(
                    "Profile '{}' not found. Available profiles: {}",
                    profile_name,
                    available
                )
            }
        }
    } else {
        Ok(config.base)
    }
}

fn merge_config(base: Config, override_cfg: Config) -> Config {
    Config {
        provider: override_cfg.provider.or(base.provider),
        api_key: override_cfg.api_key.or(base.api_key),
        base_url: override_cfg.base_url.or(base.base_url),
        default_text_model: override_cfg.default_text_model.or(base.default_text_model),
        reasoning_effort: override_cfg.reasoning_effort.or(base.reasoning_effort),
        tools_file: override_cfg.tools_file.or(base.tools_file),
        skills_dir: override_cfg.skills_dir.or(base.skills_dir),
        mcp_config_path: override_cfg.mcp_config_path.or(base.mcp_config_path),
        notes_path: override_cfg.notes_path.or(base.notes_path),
        memory_path: override_cfg.memory_path.or(base.memory_path),
        allow_shell: override_cfg.allow_shell.or(base.allow_shell),
        approval_policy: override_cfg.approval_policy.or(base.approval_policy),
        sandbox_mode: override_cfg.sandbox_mode.or(base.sandbox_mode),
        managed_config_path: override_cfg
            .managed_config_path
            .or(base.managed_config_path),
        requirements_path: override_cfg.requirements_path.or(base.requirements_path),
        max_subagents: override_cfg.max_subagents.or(base.max_subagents),
        retry: override_cfg.retry.or(base.retry),
        capacity: override_cfg.capacity.or(base.capacity),
        tui: override_cfg.tui.or(base.tui),
        hooks: override_cfg.hooks.or(base.hooks),
        providers: merge_providers(base.providers, override_cfg.providers),
        features: merge_features(base.features, override_cfg.features),
    }
}

fn merge_provider_config(base: ProviderConfig, override_cfg: ProviderConfig) -> ProviderConfig {
    ProviderConfig {
        api_key: override_cfg.api_key.or(base.api_key),
        base_url: override_cfg.base_url.or(base.base_url),
        model: override_cfg.model.or(base.model),
    }
}

fn merge_providers(
    base: Option<ProvidersConfig>,
    override_cfg: Option<ProvidersConfig>,
) -> Option<ProvidersConfig> {
    match (base, override_cfg) {
        (None, None) => None,
        (Some(base), None) => Some(base),
        (None, Some(override_cfg)) => Some(override_cfg),
        (Some(base), Some(override_cfg)) => Some(ProvidersConfig {
            deepseek: merge_provider_config(base.deepseek, override_cfg.deepseek),
            nvidia_nim: merge_provider_config(base.nvidia_nim, override_cfg.nvidia_nim),
        }),
    }
}

fn load_single_config_file(path: &Path) -> Result<Config> {
    let contents = fs::read_to_string(path)
        .with_context(|| format!("Failed to read config file: {}", path.display()))?;
    let parsed: ConfigFile = toml::from_str(&contents)
        .with_context(|| format!("Failed to parse config file: {}", path.display()))?;
    Ok(parsed.base)
}

fn apply_managed_overrides(config: &mut Config) -> Result<()> {
    let path = config
        .managed_config_path
        .as_deref()
        .map(expand_path)
        .or_else(default_managed_config_path);
    let Some(path) = path else {
        return Ok(());
    };
    if !path.exists() {
        return Ok(());
    }
    let managed = load_single_config_file(&path)?;
    *config = merge_config(config.clone(), managed);
    Ok(())
}

fn apply_requirements(config: &mut Config) -> Result<()> {
    let path = config
        .requirements_path
        .as_deref()
        .map(expand_path)
        .or_else(default_requirements_path);
    let Some(path) = path else {
        return Ok(());
    };
    if !path.exists() {
        return Ok(());
    }
    let contents = fs::read_to_string(&path)
        .with_context(|| format!("Failed to read requirements file: {}", path.display()))?;
    let requirements: RequirementsFile = toml::from_str(&contents)
        .with_context(|| format!("Failed to parse requirements file: {}", path.display()))?;

    if !requirements.allowed_approval_policies.is_empty()
        && let Some(policy) = config.approval_policy.as_ref()
    {
        let policy = policy.to_ascii_lowercase();
        if !requirements
            .allowed_approval_policies
            .iter()
            .any(|p| p.eq_ignore_ascii_case(&policy))
        {
            anyhow::bail!(
                "approval_policy '{policy}' is not allowed by requirements ({})",
                requirements.allowed_approval_policies.join(", ")
            );
        }
    }
    if !requirements.allowed_sandbox_modes.is_empty()
        && let Some(mode) = config.sandbox_mode.as_ref()
    {
        let mode = mode.to_ascii_lowercase();
        if !requirements
            .allowed_sandbox_modes
            .iter()
            .any(|m| m.eq_ignore_ascii_case(&mode))
        {
            anyhow::bail!(
                "sandbox_mode '{mode}' is not allowed by requirements ({})",
                requirements.allowed_sandbox_modes.join(", ")
            );
        }
    }

    Ok(())
}

fn merge_features(
    base: Option<FeaturesToml>,
    override_cfg: Option<FeaturesToml>,
) -> Option<FeaturesToml> {
    match (base, override_cfg) {
        (None, None) => None,
        (Some(mut base), Some(override_cfg)) => {
            for (key, value) in override_cfg.entries {
                base.entries.insert(key, value);
            }
            Some(base)
        }
        (Some(base), None) => Some(base),
        (None, Some(override_cfg)) => Some(override_cfg),
    }
}

pub fn ensure_parent_dir(path: &Path) -> Result<()> {
    if let Some(parent) = path.parent() {
        fs::create_dir_all(parent)
            .with_context(|| format!("Failed to create directory: {}", parent.display()))?;
    }
    Ok(())
}

/// Save an API key to the config file. Creates the file if it doesn't exist.
pub fn save_api_key(api_key: &str) -> Result<PathBuf> {
    fn is_api_key_assignment(line: &str) -> bool {
        let trimmed = line.trim_start();
        trimmed
            .strip_prefix("api_key")
            .is_some_and(|rest| rest.trim_start().starts_with('='))
    }

    let config_path = default_config_path()
        .context("Failed to resolve config path: home directory not found.")?;

    ensure_parent_dir(&config_path)?;

    // Don't use keychain - just write directly to config file
    // Keychain causes permission prompts on macOS for unsigned binaries
    let key_to_write = api_key.to_string();

    let content = if config_path.exists() {
        // Read existing config and update the api_key line
        let existing = fs::read_to_string(&config_path)?;
        if existing.contains("api_key") {
            // Replace existing api_key line
            let mut result = String::new();
            for line in existing.lines() {
                if is_api_key_assignment(line) {
                    let _ = writeln!(result, "api_key = \"{key_to_write}\"");
                } else {
                    result.push_str(line);
                    result.push('\n');
                }
            }
            result
        } else {
            // Prepend api_key to existing config
            format!("api_key = \"{key_to_write}\"\n{existing}")
        }
    } else {
        // Create new minimal config
        format!(
            r#"# DeepSeek TUI Configuration
# Get your API key from https://platform.deepseek.com
# Or set DEEPSEEK_API_KEY environment variable

api_key = "{key_to_write}"

# Base URL (default: https://api.deepseek.com)
# base_url = "https://api.deepseek.com"

# Default model
default_text_model = "{default_model}"

# Thinking mode (DeepSeek V4 reasoning effort):
# "off" | "low" | "medium" | "high" | "max"
# Shift+Tab in the TUI cycles between off / high / max.
reasoning_effort = "max"
"#,
            default_model = DEFAULT_TEXT_MODEL
        )
    };

    fs::write(&config_path, content)
        .with_context(|| format!("Failed to write config to {}", config_path.display()))?;
    log_sensitive_event(
        "credential.save",
        json!({
            "backend": "config_file",
            "config_path": config_path.display().to_string(),
        }),
    );

    Ok(config_path)
}

/// Check if an API key is configured (either in config or environment)
pub fn has_api_key(config: &Config) -> bool {
    // Check environment variable first (highest priority)
    if std::env::var("DEEPSEEK_API_KEY").is_ok_and(|k| !k.trim().is_empty()) {
        return true;
    }

    // Then check config file
    config
        .api_key
        .as_ref()
        .is_some_and(|k| !k.trim().is_empty() && k != API_KEYRING_SENTINEL)
}

/// Clear the API key from the config file
pub fn clear_api_key() -> Result<()> {
    // Don't clear keychain - we're not using it anymore
    // Just clear from config file

    let config_path = default_config_path()
        .context("Failed to resolve config path: home directory not found.")?;

    if !config_path.exists() {
        return Ok(());
    }

    let existing = fs::read_to_string(&config_path)?;
    let mut result = String::new();

    for line in existing.lines() {
        if !line.trim_start().starts_with("api_key") {
            result.push_str(line);
            result.push('\n');
        }
    }

    fs::write(&config_path, result)
        .with_context(|| format!("Failed to write config to {}", config_path.display()))?;
    log_sensitive_event(
        "credential.clear",
        json!({
            "backend": "config_file",
            "config_path": config_path.display().to_string(),
        }),
    );

    Ok(())
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::test_support::lock_test_env;
    use std::collections::HashMap;
    use std::env;
    use std::ffi::OsString;
    use std::time::{SystemTime, UNIX_EPOCH};

    struct EnvGuard {
        home: Option<OsString>,
        userprofile: Option<OsString>,
        deepseek_config_path: Option<OsString>,
        deepseek_provider: Option<OsString>,
        deepseek_api_key: Option<OsString>,
        deepseek_base_url: Option<OsString>,
        deepseek_model: Option<OsString>,
        deepseek_default_text_model: Option<OsString>,
        nvidia_api_key: Option<OsString>,
        nvidia_nim_api_key: Option<OsString>,
        nim_base_url: Option<OsString>,
        nvidia_base_url: Option<OsString>,
        nvidia_nim_base_url: Option<OsString>,
        nvidia_nim_model: Option<OsString>,
    }

    impl EnvGuard {
        fn new(home: &Path) -> Self {
            let home_str = OsString::from(home.as_os_str());
            let config_path = home.join(".deepseek").join("config.toml");
            let config_str = OsString::from(config_path.as_os_str());
            let home_prev = env::var_os("HOME");
            let userprofile_prev = env::var_os("USERPROFILE");
            let deepseek_config_prev = env::var_os("DEEPSEEK_CONFIG_PATH");
            let deepseek_provider_prev = env::var_os("DEEPSEEK_PROVIDER");
            let api_key_prev = env::var_os("DEEPSEEK_API_KEY");
            let base_url_prev = env::var_os("DEEPSEEK_BASE_URL");
            let model_prev = env::var_os("DEEPSEEK_MODEL");
            let default_text_model_prev = env::var_os("DEEPSEEK_DEFAULT_TEXT_MODEL");
            let nvidia_api_key_prev = env::var_os("NVIDIA_API_KEY");
            let nvidia_nim_api_key_prev = env::var_os("NVIDIA_NIM_API_KEY");
            let nim_base_url_prev = env::var_os("NIM_BASE_URL");
            let nvidia_base_url_prev = env::var_os("NVIDIA_BASE_URL");
            let nvidia_nim_base_url_prev = env::var_os("NVIDIA_NIM_BASE_URL");
            let nvidia_nim_model_prev = env::var_os("NVIDIA_NIM_MODEL");
            // Safety: test-only environment mutation guarded by a global mutex.
            unsafe {
                env::set_var("HOME", &home_str);
                env::set_var("USERPROFILE", &home_str);
                env::set_var("DEEPSEEK_CONFIG_PATH", &config_str);
                env::remove_var("DEEPSEEK_PROVIDER");
                env::remove_var("DEEPSEEK_API_KEY");
                env::remove_var("DEEPSEEK_BASE_URL");
                env::remove_var("DEEPSEEK_MODEL");
                env::remove_var("DEEPSEEK_DEFAULT_TEXT_MODEL");
                env::remove_var("NVIDIA_API_KEY");
                env::remove_var("NVIDIA_NIM_API_KEY");
                env::remove_var("NIM_BASE_URL");
                env::remove_var("NVIDIA_BASE_URL");
                env::remove_var("NVIDIA_NIM_BASE_URL");
                env::remove_var("NVIDIA_NIM_MODEL");
            }
            Self {
                home: home_prev,
                userprofile: userprofile_prev,
                deepseek_config_path: deepseek_config_prev,
                deepseek_provider: deepseek_provider_prev,
                deepseek_api_key: api_key_prev,
                deepseek_base_url: base_url_prev,
                deepseek_model: model_prev,
                deepseek_default_text_model: default_text_model_prev,
                nvidia_api_key: nvidia_api_key_prev,
                nvidia_nim_api_key: nvidia_nim_api_key_prev,
                nim_base_url: nim_base_url_prev,
                nvidia_base_url: nvidia_base_url_prev,
                nvidia_nim_base_url: nvidia_nim_base_url_prev,
                nvidia_nim_model: nvidia_nim_model_prev,
            }
        }
    }

    impl Drop for EnvGuard {
        fn drop(&mut self) {
            // Safety: test-only environment mutation guarded by a global mutex.
            unsafe {
                Self::restore_var("HOME", self.home.take());
                Self::restore_var("USERPROFILE", self.userprofile.take());
                Self::restore_var("DEEPSEEK_CONFIG_PATH", self.deepseek_config_path.take());
                Self::restore_var("DEEPSEEK_PROVIDER", self.deepseek_provider.take());
                Self::restore_var("DEEPSEEK_API_KEY", self.deepseek_api_key.take());
                Self::restore_var("DEEPSEEK_BASE_URL", self.deepseek_base_url.take());
                Self::restore_var("DEEPSEEK_MODEL", self.deepseek_model.take());
                Self::restore_var(
                    "DEEPSEEK_DEFAULT_TEXT_MODEL",
                    self.deepseek_default_text_model.take(),
                );
                Self::restore_var("NVIDIA_API_KEY", self.nvidia_api_key.take());
                Self::restore_var("NVIDIA_NIM_API_KEY", self.nvidia_nim_api_key.take());
                Self::restore_var("NIM_BASE_URL", self.nim_base_url.take());
                Self::restore_var("NVIDIA_BASE_URL", self.nvidia_base_url.take());
                Self::restore_var("NVIDIA_NIM_BASE_URL", self.nvidia_nim_base_url.take());
                Self::restore_var("NVIDIA_NIM_MODEL", self.nvidia_nim_model.take());
            }
        }
    }

    impl EnvGuard {
        /// Restore an env var to its prior value (or remove it if it was unset).
        ///
        /// # Safety
        /// Must only be called from test code guarded by a global mutex.
        unsafe fn restore_var(key: &str, prev: Option<OsString>) {
            if let Some(value) = prev {
                unsafe { env::set_var(key, value) };
            } else {
                unsafe { env::remove_var(key) };
            }
        }
    }

    #[test]
    fn save_api_key_writes_config() -> Result<()> {
        let _lock = lock_test_env();
        let nanos = SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .unwrap()
            .as_nanos();
        let temp_root = env::temp_dir().join(format!(
            "deepseek-tui-test-{}-{}",
            std::process::id(),
            nanos
        ));
        fs::create_dir_all(&temp_root)?;
        let _guard = EnvGuard::new(&temp_root);

        let path = save_api_key("test-key")?;
        let expected = temp_root.join(".deepseek").join("config.toml");
        assert_eq!(path, expected);

        let contents = fs::read_to_string(&path)?;
        assert!(contents.contains("api_key = \""));
        Ok(())
    }

    #[test]
    fn test_tilde_expansion_in_paths() -> Result<()> {
        let _lock = lock_test_env();
        let nanos = SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .unwrap()
            .as_nanos();
        let temp_root = env::temp_dir().join(format!(
            "deepseek-tui-tilde-test-{}-{}",
            std::process::id(),
            nanos
        ));
        fs::create_dir_all(&temp_root)?;
        let _guard = EnvGuard::new(&temp_root);

        let config = Config {
            skills_dir: Some("~/.deepseek/skills".to_string()),
            ..Default::default()
        };
        let expected_skills = temp_root.join(".deepseek").join("skills");
        let actual_skills = config.skills_dir();
        assert_eq!(
            actual_skills.components().collect::<Vec<_>>(),
            expected_skills.components().collect::<Vec<_>>()
        );

        Ok(())
    }

    #[test]
    fn test_load_uses_tilde_expanded_deepseek_config_path() -> Result<()> {
        let _lock = lock_test_env();
        let nanos = SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .unwrap()
            .as_nanos();
        let temp_root = env::temp_dir().join(format!(
            "deepseek-tui-load-tilde-test-{}-{}",
            std::process::id(),
            nanos
        ));
        fs::create_dir_all(&temp_root)?;
        let _guard = EnvGuard::new(&temp_root);

        let config_path = temp_root.join(".custom-deepseek").join("config.toml");
        ensure_parent_dir(&config_path)?;
        fs::write(&config_path, "api_key = \"test-key\"\n")?;

        // Safety: test-only environment mutation guarded by a global mutex.
        unsafe {
            env::set_var("DEEPSEEK_CONFIG_PATH", "~/.custom-deepseek/config.toml");
        }

        let config = Config::load(None, None)?;
        assert_eq!(config.api_key.as_deref(), Some("test-key"));
        Ok(())
    }

    #[test]
    fn test_load_falls_back_to_home_config_when_env_path_missing() -> Result<()> {
        let _lock = lock_test_env();
        let nanos = SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .unwrap()
            .as_nanos();
        let temp_root = env::temp_dir().join(format!(
            "deepseek-tui-load-fallback-test-{}-{}",
            std::process::id(),
            nanos
        ));
        fs::create_dir_all(&temp_root)?;
        let _guard = EnvGuard::new(&temp_root);

        let home_config = temp_root.join(".deepseek").join("config.toml");
        ensure_parent_dir(&home_config)?;
        fs::write(&home_config, "api_key = \"home-key\"\n")?;

        // Safety: test-only environment mutation guarded by a global mutex.
        unsafe {
            env::set_var(
                "DEEPSEEK_CONFIG_PATH",
                temp_root.join("missing-config.toml").as_os_str(),
            );
        }

        let config = Config::load(None, None)?;
        assert_eq!(config.api_key.as_deref(), Some("home-key"));
        Ok(())
    }

    #[test]
    fn test_nonexistent_profile_error() {
        let mut profiles = HashMap::new();
        profiles.insert("work".to_string(), Config::default());
        let config = ConfigFile {
            base: Config::default(),
            profiles: Some(profiles),
        };

        let err = apply_profile(config, Some("nonexistent")).unwrap_err();
        let message = err.to_string();
        assert!(message.contains("Profile 'nonexistent' not found"));
        assert!(message.contains("Available profiles"));
        assert!(message.contains("work"));
    }

    #[test]
    fn test_profile_with_no_profiles_section() {
        let config = ConfigFile {
            base: Config::default(),
            profiles: None,
        };

        let err = apply_profile(config, Some("missing")).unwrap_err();
        assert!(err.to_string().contains("Available profiles: none"));
    }

    #[test]
    fn test_save_api_key_doesnt_match_similar_keys() -> Result<()> {
        let _lock = lock_test_env();
        let nanos = SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .unwrap()
            .as_nanos();
        let temp_root = env::temp_dir().join(format!(
            "deepseek-tui-api-key-test-{}-{}",
            std::process::id(),
            nanos
        ));
        fs::create_dir_all(&temp_root)?;
        let _guard = EnvGuard::new(&temp_root);

        let config_path = temp_root.join(".deepseek").join("config.toml");
        ensure_parent_dir(&config_path)?;
        fs::write(
            &config_path,
            "api_key_backup = \"old\"\napi_key = \"current\"\n",
        )?;

        let path = save_api_key("new-key")?;
        assert_eq!(path, config_path);

        let contents = fs::read_to_string(&config_path)?;
        assert!(contents.contains("api_key_backup = \"old\""));
        assert!(contents.contains("api_key = \""));
        Ok(())
    }

    #[test]
    fn test_empty_api_key_rejected() {
        let config = Config {
            api_key: Some("   ".to_string()),
            ..Default::default()
        };
        assert!(config.validate().is_err());
    }

    #[test]
    fn test_missing_api_key_allowed() -> Result<()> {
        let config = Config::default();
        config.validate()?;
        Ok(())
    }

    #[test]
    fn apply_env_overrides_ignores_empty_api_key() -> Result<()> {
        let _lock = lock_test_env();
        let nanos = SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .unwrap()
            .as_nanos();
        let temp_root = env::temp_dir().join(format!(
            "deepseek-tui-empty-key-{}-{}",
            std::process::id(),
            nanos
        ));
        fs::create_dir_all(&temp_root)?;
        let _guard = EnvGuard::new(&temp_root);

        // Simulate a fresh user who copied .env.example to .env without
        // filling in DEEPSEEK_API_KEY: dotenv loads it as the empty string.
        // Safety: test-only environment mutation guarded by a global mutex.
        unsafe {
            env::set_var("DEEPSEEK_API_KEY", "");
        }

        let mut config = Config {
            api_key: Some("from-config-file".to_string()),
            ..Default::default()
        };
        apply_env_overrides(&mut config);

        assert_eq!(config.api_key.as_deref(), Some("from-config-file"));
        config.validate()?;
        Ok(())
    }

    #[test]
    fn normalize_model_name_handles_aliases_and_future_ids() {
        assert_eq!(
            normalize_model_name("deepseek-v3.2").as_deref(),
            Some("deepseek-v4-flash")
        );
        assert_eq!(
            normalize_model_name("deepseek-r1").as_deref(),
            Some("deepseek-v4-flash")
        );
        assert_eq!(
            normalize_model_name("DeepSeek-V4").as_deref(),
            Some("deepseek-v4")
        );
        assert_eq!(
            normalize_model_name("deepseek-ai/deepseek-v4-pro").as_deref(),
            Some("deepseek-ai/deepseek-v4-pro")
        );
        assert_eq!(
            normalize_model_name("deepseek-ai/deepseek-v4-flash").as_deref(),
            Some("deepseek-ai/deepseek-v4-flash")
        );
    }

    #[test]
    fn normalize_model_name_rejects_invalid_or_non_deepseek_ids() {
        assert!(normalize_model_name("gpt-4o").is_none());
        assert!(normalize_model_name("deepseek v4").is_none());
        assert!(normalize_model_name("").is_none());
    }

    #[test]
    fn validate_accepts_future_deepseek_model_id() -> Result<()> {
        let config = Config {
            default_text_model: Some("deepseek-v4".to_string()),
            ..Default::default()
        };
        config.validate()?;
        Ok(())
    }

    #[test]
    fn deepseek_model_env_overrides_default_text_model() -> Result<()> {
        let _lock = lock_test_env();
        let nanos = SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .unwrap()
            .as_nanos();
        let temp_root = env::temp_dir().join(format!(
            "deepseek-tui-model-env-test-{}-{}",
            std::process::id(),
            nanos
        ));
        fs::create_dir_all(&temp_root)?;
        let _guard = EnvGuard::new(&temp_root);

        // Safety: test-only environment mutation guarded by a global mutex.
        unsafe {
            env::set_var("DEEPSEEK_MODEL", "deepseek-chat");
        }

        let config = Config::load(None, None)?;
        assert_eq!(
            config.default_text_model.as_deref(),
            Some("deepseek-v4-flash")
        );
        Ok(())
    }

    #[test]
    fn nvidia_nim_provider_uses_nim_defaults() -> Result<()> {
        let config = Config {
            provider: Some("nvidia-nim".to_string()),
            ..Default::default()
        };

        config.validate()?;
        assert_eq!(config.api_provider(), ApiProvider::NvidiaNim);
        assert_eq!(config.default_model(), DEFAULT_NVIDIA_NIM_MODEL);
        assert_eq!(config.deepseek_base_url(), DEFAULT_NVIDIA_NIM_BASE_URL);
        Ok(())
    }

    #[test]
    fn nvidia_nim_provider_normalizes_deepseek_v4_pro_alias() -> Result<()> {
        let _lock = lock_test_env();
        let nanos = SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .unwrap()
            .as_nanos();
        let temp_root = env::temp_dir().join(format!(
            "deepseek-tui-nim-model-alias-test-{}-{}",
            std::process::id(),
            nanos
        ));
        fs::create_dir_all(&temp_root)?;
        let _guard = EnvGuard::new(&temp_root);

        let config_path = temp_root.join(".deepseek").join("config.toml");
        ensure_parent_dir(&config_path)?;
        fs::write(
            &config_path,
            "provider = \"nvidia-nim\"\ndefault_text_model = \"deepseek-v4-pro\"\napi_key = \"nim-key\"\n",
        )?;

        let config = Config::load(None, None)?;
        assert_eq!(config.api_provider(), ApiProvider::NvidiaNim);
        assert_eq!(
            config.default_text_model.as_deref(),
            Some(DEFAULT_NVIDIA_NIM_MODEL)
        );
        Ok(())
    }

    #[test]
    fn nvidia_nim_provider_normalizes_deepseek_v4_flash_alias() -> Result<()> {
        let config = Config {
            provider: Some("nvidia-nim".to_string()),
            default_text_model: Some("deepseek-v4-flash".to_string()),
            ..Default::default()
        };

        config.validate()?;
        assert_eq!(config.default_model(), DEFAULT_NVIDIA_NIM_FLASH_MODEL);
        Ok(())
    }

    #[test]
    fn nvidia_nim_env_overrides_provider_and_credentials() -> Result<()> {
        let _lock = lock_test_env();
        let nanos = SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .unwrap()
            .as_nanos();
        let temp_root = env::temp_dir().join(format!(
            "deepseek-tui-nim-env-test-{}-{}",
            std::process::id(),
            nanos
        ));
        fs::create_dir_all(&temp_root)?;
        let _guard = EnvGuard::new(&temp_root);

        // Safety: test-only environment mutation guarded by a global mutex.
        unsafe {
            env::set_var("DEEPSEEK_PROVIDER", "nvidia-nim");
            env::set_var("NVIDIA_API_KEY", "nim-env-key");
            env::set_var("NVIDIA_NIM_MODEL", "deepseek-ai/deepseek-v4-pro");
        }

        let config = Config::load(None, None)?;
        assert_eq!(config.api_provider(), ApiProvider::NvidiaNim);
        assert_eq!(config.deepseek_api_key()?, "nim-env-key");
        assert_eq!(config.default_model(), DEFAULT_NVIDIA_NIM_MODEL);
        Ok(())
    }

    #[test]
    fn nvidia_nim_env_accepts_short_nim_base_url_alias() -> Result<()> {
        let _lock = lock_test_env();
        let nanos = SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .unwrap()
            .as_nanos();
        let temp_root = env::temp_dir().join(format!(
            "deepseek-tui-nim-base-url-alias-test-{}-{}",
            std::process::id(),
            nanos
        ));
        fs::create_dir_all(&temp_root)?;
        let _guard = EnvGuard::new(&temp_root);

        // Safety: test-only environment mutation guarded by a global mutex.
        unsafe {
            env::set_var("DEEPSEEK_PROVIDER", "nvidia-nim");
            env::set_var("NIM_BASE_URL", "https://short-nim.example/v1");
        }

        let config = Config::load(None, None)?;
        assert_eq!(config.api_provider(), ApiProvider::NvidiaNim);
        assert_eq!(config.deepseek_base_url(), "https://short-nim.example/v1");
        Ok(())
    }

    #[test]
    fn nvidia_nim_env_accepts_facade_base_url_forwarding() -> Result<()> {
        let _lock = lock_test_env();
        let nanos = SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .unwrap()
            .as_nanos();
        let temp_root = env::temp_dir().join(format!(
            "deepseek-tui-nim-forwarded-base-url-test-{}-{}",
            std::process::id(),
            nanos
        ));
        fs::create_dir_all(&temp_root)?;
        let _guard = EnvGuard::new(&temp_root);

        // Safety: test-only environment mutation guarded by a global mutex.
        unsafe {
            env::set_var("DEEPSEEK_PROVIDER", "nvidia-nim");
            env::set_var("DEEPSEEK_BASE_URL", "https://forwarded-nim.example/v1");
        }

        let config = Config::load(None, None)?;
        assert_eq!(config.api_provider(), ApiProvider::NvidiaNim);
        assert_eq!(
            config.deepseek_base_url(),
            "https://forwarded-nim.example/v1"
        );
        Ok(())
    }

    #[test]
    fn nvidia_nim_reads_facade_provider_table() -> Result<()> {
        let _lock = lock_test_env();
        let nanos = SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .unwrap()
            .as_nanos();
        let temp_root = env::temp_dir().join(format!(
            "deepseek-tui-nim-provider-table-test-{}-{}",
            std::process::id(),
            nanos
        ));
        fs::create_dir_all(&temp_root)?;
        let _guard = EnvGuard::new(&temp_root);

        let config_path = temp_root.join(".deepseek").join("config.toml");
        ensure_parent_dir(&config_path)?;
        fs::write(
            &config_path,
            r#"provider = "nvidia-nim"
default_text_model = "deepseek-v4-flash"

[providers.nvidia_nim]
api_key = "nim-table-key"
base_url = "https://nim-table.example/v1"
model = "deepseek-v4-pro"
"#,
        )?;

        let config = Config::load(None, None)?;
        assert_eq!(config.api_provider(), ApiProvider::NvidiaNim);
        assert_eq!(config.deepseek_api_key()?, "nim-table-key");
        assert_eq!(config.deepseek_base_url(), "https://nim-table.example/v1");
        assert_eq!(config.default_model(), DEFAULT_NVIDIA_NIM_MODEL);
        Ok(())
    }
}