use crate::budget::CreditTier;
use crate::persona::{Persona, PersonaRegistry};
use crate::pipeline::PipelineConfig;
use serde::{Deserialize, Serialize};
use std::fs;
use std::path::{Path, PathBuf};

const KEYRING_SERVICE: &str = "brokecrew";
const KEYRING_USER: &str = "openrouter_api_key";
const DEFAULT_PERSONAS_TOML: &str = include_str!("../config/personas.example.toml");

fn default_persona_str() -> String {
    "general".to_string()
}
fn default_router_model() -> String {
    "liquid/lfm-2.5-2.6b:free".to_string()
}
fn default_complexity_threshold() -> u8 {
    7
}
fn default_credit_tier() -> CreditTier {
    CreditTier::LowBalance
}
fn default_base_url() -> String {
    "https://openrouter.ai/api/v1".to_string()
}
fn default_theme_str() -> String {
    "opencode".to_string()
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AppConfigFile {
    #[serde(default = "default_persona_str")]
    pub default_persona: String,
    #[serde(default = "default_router_model")]
    pub router_model: String,
    #[serde(default = "default_complexity_threshold")]
    pub complexity_threshold: u8,
    #[serde(default)]
    pub allow_stealth: bool,
    #[serde(default = "default_credit_tier")]
    pub credit_tier: CreditTier,
    #[serde(default = "default_base_url")]
    pub openrouter_base_url: String,
    #[serde(default = "default_theme_str")]
    pub theme: String,
    pub api_key: Option<String>,
}

impl Default for AppConfigFile {
    fn default() -> Self {
        Self {
            default_persona: default_persona_str(),
            router_model: default_router_model(),
            complexity_threshold: default_complexity_threshold(),
            allow_stealth: false,
            credit_tier: default_credit_tier(),
            openrouter_base_url: default_base_url(),
            theme: default_theme_str(),
            api_key: None,
        }
    }
}

#[derive(Debug, Deserialize, Default)]
pub struct PersonasConfigFile {
    #[serde(rename = "persona", default)]
    pub personas: Vec<Persona>,
    #[serde(rename = "pipeline", default)]
    pub pipelines: Vec<PipelineConfig>,
}

pub struct AppConfig {
    pub default_persona: String,
    pub router_model: String,
    pub complexity_threshold: u8,
    pub allow_stealth: bool,
    pub credit_tier: CreditTier,
    pub openrouter_base_url: String,
    pub theme: String,
    pub api_key: Option<String>,
    pub persona_registry: PersonaRegistry,
    pub pipelines: Vec<PipelineConfig>,
    pub config_dir: PathBuf,
}

impl AppConfig {
    pub fn default_config_dir() -> PathBuf {
        dirs::config_dir()
            .map(|p| p.join("brokecrew"))
            .unwrap_or_else(|| PathBuf::from(".brokecrew"))
    }

    pub fn load_from_paths(
        config_path: Option<&Path>,
        personas_path: Option<&Path>,
        cli_api_key: Option<String>,
    ) -> Result<Self, String> {
        let config_dir = Self::default_config_dir();

        // 1. Load config.toml
        let config_file_path = config_path
            .map(PathBuf::from)
            .unwrap_or_else(|| config_dir.join("config.toml"));

        let app_file = if config_file_path.exists() {
            let data = fs::read_to_string(&config_file_path)
                .map_err(|e| format!("Failed to read {}: {e}", config_file_path.display()))?;
            toml::from_str::<AppConfigFile>(&data)
                .map_err(|e| format!("Failed to parse {}: {e}", config_file_path.display()))?
        } else {
            AppConfigFile::default()
        };

        // 2. Load personas.toml
        let personas_file_path = personas_path
            .map(PathBuf::from)
            .unwrap_or_else(|| config_dir.join("personas.toml"));

        let personas_config = if personas_file_path.exists() {
            let data = fs::read_to_string(&personas_file_path)
                .map_err(|e| format!("Failed to read {}: {e}", personas_file_path.display()))?;
            toml::from_str::<PersonasConfigFile>(&data)
                .map_err(|e| format!("Failed to parse {}: {e}", personas_file_path.display()))?
        } else {
            // Fallback to built-in personas.example.toml content
            toml::from_str::<PersonasConfigFile>(DEFAULT_PERSONAS_TOML)
                .map_err(|e| format!("Failed to parse bundled personas: {e}"))?
        };

        // 3. Resolve API Key: CLI -> Env -> Keyring -> Config file
        let api_key = Self::resolve_api_key(cli_api_key, app_file.api_key, true);

        Ok(Self {
            default_persona: app_file.default_persona,
            router_model: app_file.router_model,
            complexity_threshold: app_file.complexity_threshold,
            allow_stealth: app_file.allow_stealth,
            credit_tier: app_file.credit_tier,
            openrouter_base_url: app_file.openrouter_base_url,
            theme: app_file.theme,
            api_key,
            persona_registry: PersonaRegistry::new(personas_config.personas),
            pipelines: personas_config.pipelines,
            config_dir,
        })
    }

    /// Persists the selected theme into `config.toml`
    pub fn save_theme(config_dir: &Path, theme: &str) -> Result<(), String> {
        let config_file_path = config_dir.join("config.toml");
        let mut app_file = if config_file_path.exists() {
            let data = fs::read_to_string(&config_file_path)
                .map_err(|e| format!("Failed to read {}: {e}", config_file_path.display()))?;
            toml::from_str::<AppConfigFile>(&data).unwrap_or_default()
        } else {
            AppConfigFile::default()
        };

        app_file.theme = theme.to_string();
        let serialized = toml::to_string_pretty(&app_file)
            .map_err(|e| format!("Failed to serialize config: {e}"))?;

        fs::create_dir_all(config_dir).map_err(|e| format!("Failed to create config dir: {e}"))?;
        fs::write(&config_file_path, serialized)
            .map_err(|e| format!("Failed to write {}: {e}", config_file_path.display()))?;

        Ok(())
    }

    /// Resolves the API key using precedence:
    /// 1. CLI argument
    /// 2. `OPENROUTER_API_KEY` environment variable
    /// 3. OS Keyring
    /// 4. Config file
    pub fn resolve_api_key(
        cli_key: Option<String>,
        config_file_key: Option<String>,
        use_keyring: bool,
    ) -> Option<String> {
        if let Some(key) = cli_key.filter(|k| !k.trim().is_empty()) {
            return Some(key.trim().to_string());
        }

        if let Ok(env_key) = std::env::var("OPENROUTER_API_KEY") {
            if !env_key.trim().is_empty() {
                return Some(env_key.trim().to_string());
            }
        }

        if use_keyring {
            if let Ok(entry) = keyring::Entry::new(KEYRING_SERVICE, KEYRING_USER) {
                if let Ok(secret) = entry.get_password() {
                    if !secret.trim().is_empty() {
                        return Some(secret.trim().to_string());
                    }
                }
            }
        }

        if let Some(key) = config_file_key.filter(|k| !k.trim().is_empty()) {
            return Some(key.trim().to_string());
        }

        None
    }

    /// Saves API key securely to the OS credential store
    pub fn save_api_key_to_keyring(api_key: &str) -> Result<(), String> {
        let entry = keyring::Entry::new(KEYRING_SERVICE, KEYRING_USER)
            .map_err(|e| format!("Failed to access OS keyring: {e}"))?;
        entry
            .set_password(api_key.trim())
            .map_err(|e| format!("Failed to store secret in OS keyring: {e}"))
    }
}

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

    #[test]
    fn test_resolve_api_key_priority() {
        // 1. CLI flag has highest priority
        let key = AppConfig::resolve_api_key(
            Some("cli-key-123".into()),
            Some("file-key-456".into()),
            false,
        );
        assert_eq!(key, Some("cli-key-123".into()));

        // 2. Fallback to config file when no env or cli
        let key = AppConfig::resolve_api_key(None, Some("file-key-456".into()), false);
        assert_eq!(key, Some("file-key-456".into()));
    }

    #[test]
    fn test_personas_config_file_parse() {
        let toml_str = r#"
        [[persona]]
        name = "tester"
        system_prompt = "You test code"
        trigger_words = ["test", "verify"]

        [[persona.candidates]]
        id = "model-a:free"
        tier = "free"
        is_stealth = false

        [[pipeline]]
        name = "test-pipe"
        steps = [
            { persona = "tester" }
        ]
        "#;

        let parsed: PersonasConfigFile = toml::from_str(toml_str).unwrap();
        assert_eq!(parsed.personas.len(), 1);
        assert_eq!(parsed.personas[0].name, "tester");
        assert_eq!(parsed.pipelines.len(), 1);
        assert_eq!(parsed.pipelines[0].name, "test-pipe");
    }

    #[test]
    fn test_bundled_personas_valid() {
        let parsed: PersonasConfigFile = toml::from_str(DEFAULT_PERSONAS_TOML).unwrap();
        assert!(parsed.personas.len() >= 3);
        assert!(!parsed.pipelines.is_empty());
    }

    #[test]
    fn test_theme_persistence() {
        let temp_dir = tempfile::tempdir().unwrap();
        AppConfig::save_theme(temp_dir.path(), "dracula").expect("save theme");
        let loaded =
            AppConfig::load_from_paths(Some(&temp_dir.path().join("config.toml")), None, None)
                .expect("load config");
        assert_eq!(loaded.theme, "dracula");
    }
}