//! JSON file–backed `AppConfigRepository` with Claude credential auto-detection.

use std::path::Path;

use serde::{Deserialize, Serialize};
use zesdex_domain::cms::{
    AppConfig, AppConfigRepository, ModelRole, ProviderConfig, RepositoryError,
};

use crate::utils::write_json_atomic;

/// File-based `AppConfigRepository` that reads/writes `app_config.json`.
#[derive(Debug, Clone, Default)]
pub struct JsonAppConfigRepository;

impl JsonAppConfigRepository {
    pub fn new() -> Self {
        Self
    }
}

#[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>,
    #[serde(alias = "customModel", alias = "model")]
    custom_model: Option<String>,
}

fn claude_settings_from_file() -> Option<ClaudeSettings> {
    let path = dirs::home_dir()?.join(".claude").join("settings.json");
    let content = std::fs::read_to_string(&path).ok()?;
    serde_json::from_str(&content).ok()
}

fn detect_claude_settings_provider() -> Option<(ProviderConfig, Option<String>)> {
    let settings = claude_settings_from_file();

    let file_creds = settings.as_ref().and_then(|s| {
        let env = s.env.as_ref()?;
        Some((
            env.anthropic_base_url.clone()?,
            env.anthropic_api_key.clone()?,
        ))
    });

    let env_creds = || -> 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))
    };

    let custom_model = settings.and_then(|s| s.custom_model);

    let (base_url, key) = file_creds.or_else(env_creds)?;

    Some((
        ProviderConfig {
            api_base: base_url,
            api_key_env: Some("ANTHROPIC_API_KEY".to_string()),
            default_model: custom_model.clone(),
            default_api_key: Some(key),
        },
        custom_model,
    ))
}

/// Apply a detected Claude provider + custom model onto an `AppConfig`.
///
/// Pure (no I/O) so it can be unit-tested. Flow:
///   1. Always `insert`s the "claude" provider (refreshing a possibly stale
///      persisted entry with the current base URL + key from settings.json).
///   2. Registers known Claude model roles if missing.
///   3. Always sets `default_provider = "claude"` and
///      `default_model = custom_model.unwrap_or("claude-opus-5")` so Opus
///      is the default whenever `~/.claude/settings.json` is present.
fn apply_claude_provider(
    cfg: &mut AppConfig,
    claude_provider: ProviderConfig,
    custom_model: Option<String>,
) {
    cfg.providers.insert("claude".to_string(), claude_provider);

    let claude_models: [(&str, &str); 3] = [
        ("claude-opus-5", "claude-opus-5"),
        ("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),
            });
    }

    if let Some(custom) = &custom_model {
        cfg.model_roles.entry(custom.clone()).or_insert(ModelRole {
            provider: "claude".to_string(),
            model: custom.clone(),
            max_tokens: Some(8192),
            context_window: Some(200_000),
            temperature: Some(0.7),
        });
    }

    // Always prefer the Claude provider + Opus model when settings.json
    // is present — this is the user's explicit custom endpoint choice.
    cfg.default_provider = "claude".to_string();
    cfg.default_model = custom_model.unwrap_or_else(|| "claude-opus-5".to_string());
}

impl AppConfigRepository for JsonAppConfigRepository {
    fn load(&self, base_dir: &Path) -> Result<AppConfig, RepositoryError> {
        let path = base_dir.join("app_config.json");
        let mut cfg: AppConfig = match std::fs::read_to_string(&path) {
            Ok(s) => serde_json::from_str(&s)?,
            Err(e) if e.kind() == std::io::ErrorKind::NotFound => AppConfig::default(),
            Err(e) => return Err(RepositoryError::Io(e)),
        };

        let defaults = AppConfig::default();
        for (name, provider) in defaults.providers {
            cfg.providers.entry(name).or_insert(provider);
        }

        if let Some((claude_provider, custom_model)) = detect_claude_settings_provider() {
            apply_claude_provider(&mut cfg, claude_provider, custom_model);
        }

        Ok(cfg)
    }

    fn save(&self, base_dir: &Path, config: &AppConfig) -> Result<(), RepositoryError> {
        std::fs::create_dir_all(base_dir)?;
        let path = base_dir.join("app_config.json");
        write_json_atomic(&path, config, None)?;
        Ok(())
    }
}

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

    fn claude_provider(base: &str, key: Option<&str>) -> ProviderConfig {
        ProviderConfig {
            api_base: base.to_string(),
            api_key_env: Some("ANTHROPIC_API_KEY".to_string()),
            default_model: Some("claude-opus-5".to_string()),
            default_api_key: key.map(|s| s.to_string()),
        }
    }

    #[test]
    fn claude_settings_parse_env() {
        let parsed: ClaudeSettings = serde_json::from_str(
            r#"{"env":{"ANTHROPIC_BASE_URL":"https://9router.example/v1","ANTHROPIC_API_KEY":"sk-test"}}"#,
        )
        .unwrap();
        let env = parsed.env.unwrap();
        assert_eq!(
            env.anthropic_base_url.as_deref(),
            Some("https://9router.example/v1")
        );
        assert_eq!(env.anthropic_api_key.as_deref(), Some("sk-test"));
    }

    #[test]
    fn apply_claude_refreshes_stale_provider_and_sets_opus_default() {
        // Simulate a previously-persisted app_config.json with a STALE claude
        // provider + non-opus default (e.g. user had switched provider).
        let mut cfg = AppConfig {
            providers: {
                let mut m = HashMap::new();
                m.insert(
                    "claude".to_string(),
                    claude_provider("https://old.example/v1", Some("sk-old")),
                );
                m
            },
            model_roles: HashMap::new(),
            default_provider: "router".to_string(),
            default_model: "other-model".to_string(),
            default_context_window: 256_000,
        };

        // Detect returned a fresh provider from ~/.claude/settings.json.
        apply_claude_provider(
            &mut cfg,
            claude_provider("https://9router.example/v1", Some("sk-new")),
            None,
        );

        let claude = cfg.providers.get("claude").unwrap();
        assert_eq!(claude.api_base, "https://9router.example/v1");
        assert_eq!(claude.default_api_key.as_deref(), Some("sk-new"));
        // Insert (not or_insert) → stale entry refreshed.
        assert_eq!(cfg.default_provider, "claude");
        assert_eq!(cfg.default_model, "claude-opus-5");

        // Claude model roles registered.
        assert!(cfg.model_roles.contains_key("claude-opus-5"));
        assert!(cfg.model_roles.contains_key("claude-sonnet-5"));
        assert!(cfg.model_roles.contains_key("claude-haiku-4-5"));
    }

    #[test]
    fn apply_claude_honors_custom_model_from_settings() {
        let mut cfg = AppConfig::default();
        apply_claude_provider(
            &mut cfg,
            claude_provider("https://9router.example/v1", Some("sk-new")),
            Some("claude-opus-5".to_string()),
        );
        assert_eq!(cfg.default_model, "claude-opus-5");
        assert!(cfg.model_roles.contains_key("claude-opus-5"));
    }

    #[test]
    fn detect_uses_env_creds_as_fallback() {
        // When ~/.claude/settings.json is absent/unreadable, the env-var
        // fallback should produce a "claude" provider. Set env vars, call
        // detect, and assert the resulting provider uses them.
        std::env::set_var("ANTHROPIC_BASE_URL", "https://env.example/v1");
        std::env::set_var("ANTHROPIC_API_KEY", "sk-env");
        match detect_claude_settings_provider() {
            Some((provider, _custom)) => {
                // If the real settings.json exists it wins (base could be the
                // real 9router URL); otherwise env creds are used. Either way,
                // the provider must have api_key_env pointing at ANTHROPIC_API_KEY.
                assert_eq!(provider.api_key_env.as_deref(), Some("ANTHROPIC_API_KEY"));
            }
            None => {
                // No file + no env (shouldn't happen since we just set env).
                panic!("expected env fallback to produce a provider");
            }
        }
        std::env::remove_var("ANTHROPIC_BASE_URL");
        std::env::remove_var("ANTHROPIC_API_KEY");
    }
}