//! Application-level configuration: LLM providers, model roles, and defaults,
//! persisted to `app_config.json` in the store directory.

use serde::{Deserialize, Serialize};
use std::collections::HashMap;

/// Top-level application config: registered providers, named model roles,
/// and which provider/model to use by default.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AppConfig {
    pub providers: HashMap<String, ProviderConfig>,
    pub model_roles: HashMap<String, ModelRole>,
    pub default_provider: String,
    pub default_model: String,
    pub default_context_window: u32,
}

/// Connection details for a single LLM provider (base URL, API key source).
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ProviderConfig {
    pub api_base: String,
    pub api_key_env: Option<String>,
    pub default_model: Option<String>,
    pub default_api_key: Option<String>,
}

/// A named role (e.g. "default") mapping to a specific provider/model and
/// its generation parameters.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ModelRole {
    pub provider: String,
    pub model: String,
    pub max_tokens: Option<u32>,
    pub context_window: Option<u32>,
    pub temperature: Option<f32>,
}

impl Default for AppConfig {
    fn default() -> Self {
        let mut providers = HashMap::new();
        providers.insert("zen".to_string(), ProviderConfig {
            api_base: "https://opencode.ai/zen/v1".to_string(),
            api_key_env: Some("API_KEY".to_string()),
            default_model: Some("deepseek-v4-flash-free".to_string()),
            default_api_key: None,
        });
        providers.insert("router".to_string(), ProviderConfig {
            api_base: "https://9router.asepharyana.my.id/v1".to_string(),
            api_key_env: Some("ROUTER_API_KEY".to_string()),
            default_model: Some("claude-opus-4-8".to_string()),
            default_api_key: None,
        });
        let mut model_roles = HashMap::new();
        model_roles.insert("default".to_string(), ModelRole {
            provider: "zen".to_string(),
            model: "deepseek-v4-flash-free".to_string(),
            max_tokens: None,
            context_window: None,
            temperature: Some(0.7),
        });
        AppConfig {
            providers,
            model_roles,
            default_provider: "zen".to_string(),
            default_model: "deepseek-v4-flash-free".to_string(),
            default_context_window: 256_000,
        }
    }
}

impl AppConfig {
    /// Load app config from disk, falling back to defaults on any failure.
    ///
    /// Flow: read `<store>/app_config.json` → JSON-parse → on missing file
    /// or parse error, use `Self::default()` → merge any default providers
    /// not already present in the loaded config.
    ///
    /// Why: the merge step lets newly-added default providers (e.g. a new
    /// release adding a provider) appear even in configs saved by older
    /// versions, without clobbering user-edited entries with the same name.
    ///
    /// Return: a fully-populated `AppConfig`, never fails.
    pub fn load() -> Self {
        let store = super::store::Store::new();
        let path = store.base_dir.join("app_config.json");
        let mut cfg: AppConfig = match std::fs::read_to_string(&path) {
            Ok(s) => match serde_json::from_str(&s) {
                Ok(c) => c,
                Err(e) => {
                    tracing::warn!(
                        "warning: failed to parse config file '{}': {}. Loading defaults.",
                        path.display(), e
                    );
                    Self::default()
                }
            },
            Err(_) => Self::default(),
        };
        // Merge any default providers not present in the loaded config
        let defaults = Self::default();
        for (name, provider) in defaults.providers {
            cfg.providers.entry(name).or_insert(provider);
        }
        // Auto-detect provider from ~/.claude/settings.json
        if let Some(claude_provider) = detect_claude_settings_provider() {
            cfg.providers.entry("claude".to_string()).or_insert(claude_provider);
            // Register known Claude models as named model roles
            let claude_models = [
                ("claude-opus-4-8", "claude-opus-4-8"),
                ("claude-sonnet-5", "claude-sonnet-5"),
                ("claude-haiku-4-5", "claude-haiku-4-5-20251001"),
            ];
            for (role_name, model_name) in &claude_models {
                cfg.model_roles.entry(role_name.to_string()).or_insert(ModelRole {
                    provider: "claude".to_string(),
                    model: model_name.to_string(),
                    max_tokens: Some(8192),
                    context_window: Some(200_000),
                    temperature: Some(0.7),
                });
            }
            // Set as default provider only if user hasn't picked a custom default
            if cfg.default_provider == defaults.default_provider {
                cfg.default_provider = "claude".to_string();
                cfg.default_model = "claude-opus-4-8".to_string();
            }
        }
        cfg
    }
}

/// Configuration structure inside `~/.claude/settings.json`.
#[derive(Debug, Clone, Serialize, Deserialize)]
struct ClaudeEnv {
    #[serde(alias = "ANTHROPIC_BASE_URL")]
    anthropic_base_url: Option<String>,
    #[serde(alias = "ANTHROPIC_API_KEY")]
    anthropic_api_key: Option<String>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
struct ClaudeSettings {
    env: Option<ClaudeEnv>,
}

/// Return a `ProviderConfig` for the Claude provider, checking both
/// `~/.claude/settings.json` and the process environment.
///
/// Flow: try the file (`env.ANTHROPIC_BASE_URL` + `env.ANTHROPIC_API_KEY`)
/// first → fall back to the `ANTHROPIC_BASE_URL` / `ANTHROPIC_API_KEY` env
/// vars → if neither source has both values, return `None`.
///
/// Why: Claude Code may inject credentials via env vars (OAuth session) rather
/// than through its settings file, so reading only the file misses them.
fn detect_claude_settings_provider() -> Option<ProviderConfig> {
    // Prefer the file, then fall back to env vars.
    let (base_url, key) = claude_credentials_from_file()
        .or_else(claude_credentials_from_env)?;
    Some(ProviderConfig {
        api_base: base_url,
        // Keep the env-var name so runtime env overrides still work.
        api_key_env: Some("ANTHROPIC_API_KEY".to_string()),
        default_model: None,
        // Store the key read from the file as a direct fallback.
        // Without this, subagent/engine.rs resolve_provider_config() falls
        // through to std::env::var("ANTHROPIC_API_KEY") which is only
        // injected into the Claude Code process — not into zesdex.  Workflow
        // nodes therefore got an empty key and failed with
        // "no API key configured for provider 'claude'", even though the
        // main agent succeeded (it has a DEFAULT_API_KEY fallback that
        // subagents intentionally do not have).
        default_api_key: Some(key),
    })
}

/// Try to read Claude credentials from `~/.claude/settings.json`'s `env` block.
fn claude_credentials_from_file() -> Option<(String, String)> {
    let path = dirs::home_dir()?.join(".claude").join("settings.json");
    let content = std::fs::read_to_string(&path).ok()?;
    let settings: ClaudeSettings = serde_json::from_str(&content).ok()?;
    let env = settings.env?;
    let base_url = env.anthropic_base_url?;
    let key = env.anthropic_api_key?;
    Some((base_url, key))
}

/// Try to read Claude credentials from `ANTHROPIC_BASE_URL` /
/// `ANTHROPIC_API_KEY` environment variables.
fn claude_credentials_from_env() -> Option<(String, String)> {
    let base_url = std::env::var("ANTHROPIC_BASE_URL").ok()?;
    let key = std::env::var("ANTHROPIC_API_KEY").ok()?;
    Some((base_url, key))
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn claude_credentials_from_env_resolves_real_env_vars() {
        // In the test runner's environment ANTHROPIC_BASE_URL and
        // ANTHROPIC_API_KEY may or may not be set — we only verify that
        // the function returns Some(..) when both are present.
        let Some((b, k)) = claude_credentials_from_env() else {
            // Not an error: CI / local without the vars.
            return;
        };
        assert!(!b.is_empty(), "ANTHROPIC_BASE_URL must not be empty");
        assert!(!k.is_empty(), "ANTHROPIC_API_KEY must not be empty");
    }
}