//! Configuration management for the Provisioning MCP Server

use std::env;
use std::path::{Path, PathBuf};

use anyhow::{Context, Result};
use platform_config::ConfigLoader;
use serde::{Deserialize, Serialize};

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Config {
    /// Path to the provisioning system
    pub provisioning_path: PathBuf,

    /// AI provider configuration
    pub ai: AIConfig,

    /// Server configuration
    pub server: ServerConfig,

    /// Debug mode
    pub debug: bool,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AIConfig {
    /// Enable AI capabilities
    pub enabled: bool,

    /// AI provider (openai, claude, generic)
    pub provider: String,

    /// API endpoint URL
    pub api_endpoint: Option<String>,

    /// API key (loaded from environment)
    pub api_key: Option<String>,

    /// Model name
    pub model: Option<String>,

    /// Maximum tokens for responses
    pub max_tokens: u32,

    /// Temperature for creativity (0.0-1.0)
    pub temperature: f32,

    /// Request timeout in seconds
    pub timeout: u64,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ServerConfig {
    /// Server name/identifier
    pub name: String,

    /// Server version
    pub version: String,

    /// Enable resource capabilities
    pub enable_resources: bool,

    /// Enable tool change notifications
    pub enable_tool_notifications: bool,
}

impl Default for Config {
    fn default() -> Self {
        Self {
            provisioning_path: PathBuf::from("/usr/local/provisioning"),
            ai: AIConfig::default(),
            server: ServerConfig::default(),
            debug: false,
        }
    }
}

impl Default for AIConfig {
    fn default() -> Self {
        Self {
            enabled: true,
            provider: "openai".to_string(),
            api_endpoint: None,
            api_key: None,
            model: Some("gpt-4".to_string()),
            max_tokens: 2048,
            temperature: 0.3,
            timeout: 30,
        }
    }
}

impl Default for ServerConfig {
    fn default() -> Self {
        Self {
            name: "provisioning-server-rust".to_string(),
            version: env!("CARGO_PKG_VERSION").to_string(),
            enable_resources: true,
            enable_tool_notifications: true,
        }
    }
}

impl ConfigLoader for Config {
    fn service_name() -> &'static str {
        "mcp-server"
    }

    fn load_from_hierarchy() -> std::result::Result<Self, Box<dyn std::error::Error + Send + Sync>>
    {
        // Use platform-config's hierarchy resolution
        let service = Self::service_name();

        if let Some(path) = platform_config::resolve_config_path(service) {
            return Self::from_path(&path);
        }

        // Fallback to defaults
        Ok(Self::default())
    }

    fn apply_env_overrides(
        &mut self,
    ) -> std::result::Result<(), Box<dyn std::error::Error + Send + Sync>> {
        self.load_from_env().map_err(|e| {
            // Convert anyhow::Error to Box<dyn Error>
            let err_msg = format!("{}", e);
            Box::new(std::io::Error::other(err_msg)) as Box<dyn std::error::Error + Send + Sync>
        })
    }

    fn from_path<P: AsRef<Path>>(
        path: P,
    ) -> std::result::Result<Self, Box<dyn std::error::Error + Send + Sync>> {
        let path = path.as_ref();
        let json_value = platform_config::format::load_config(path).map_err(|e| {
            let err: Box<dyn std::error::Error + Send + Sync> = Box::new(e);
            err
        })?;

        serde_json::from_value(json_value).map_err(|e| {
            let err_msg = format!("Failed to deserialize config from {:?}: {}", path, e);
            Box::new(std::io::Error::new(
                std::io::ErrorKind::InvalidData,
                err_msg,
            )) as Box<dyn std::error::Error + Send + Sync>
        })
    }
}

impl Config {
    /// Load configuration with hierarchical fallback logic:
    /// 1. Explicit config path (parameter or MCP_SERVER_CONFIG env var)
    /// 2. Mode-specific config:
    ///    provisioning/platform/config/mcp-server.{mode}.ncl or .toml
    /// 3. Built-in defaults
    ///
    /// Then environment variables override specific fields.
    pub fn load(
        config_path: Option<PathBuf>,
        provisioning_path: Option<PathBuf>,
        debug: bool,
    ) -> Result<Self> {
        let mut config = if let Some(path) = config_path {
            Self::from_path(&path)
                .map_err(|e| anyhow::anyhow!("Failed to load from path: {}", e))?
        } else {
            <Self as ConfigLoader>::load()
                .map_err(|e| anyhow::anyhow!("Failed to load config: {}", e))?
        };

        // Override with command line arguments
        if let Some(path) = provisioning_path {
            config.provisioning_path = path;
        }
        config.debug = debug;

        // Validate configuration
        config.validate()?;

        Ok(config)
    }

    /// Load configuration from file (legacy wrapper for compatibility)
    fn from_file<P: AsRef<Path>>(path: P) -> Result<Self> {
        Self::from_path(&path).map_err(|e| anyhow::anyhow!("Failed to load from file: {}", e))
    }

    /// Load configuration from environment variables
    fn load_from_env(&mut self) -> Result<()> {
        // Provisioning path
        if let Ok(path) = env::var("PROVISIONING_PATH") {
            self.provisioning_path = PathBuf::from(path);
        }

        // AI configuration
        if let Ok(enabled) = env::var("PROVISIONING_AI_ENABLED") {
            self.ai.enabled = enabled.parse().unwrap_or(true);
        }

        if let Ok(provider) = env::var("PROVISIONING_AI_PROVIDER") {
            self.ai.provider = provider;
        }

        if let Ok(endpoint) = env::var("PROVISIONING_AI_ENDPOINT") {
            self.ai.api_endpoint = Some(endpoint);
        }

        // Load API keys from environment
        self.ai.api_key = match self.ai.provider.as_str() {
            "openai" => env::var("OPENAI_API_KEY").ok(),
            "claude" => env::var("ANTHROPIC_API_KEY").ok(),
            "generic" => env::var("LLM_API_KEY").ok(),
            _ => None,
        };

        if let Ok(model) = env::var("PROVISIONING_AI_MODEL") {
            self.ai.model = Some(model);
        }

        if let Ok(max_tokens) = env::var("PROVISIONING_AI_MAX_TOKENS") {
            self.ai.max_tokens = max_tokens.parse().unwrap_or(2048);
        }

        if let Ok(temperature) = env::var("PROVISIONING_AI_TEMPERATURE") {
            self.ai.temperature = temperature.parse().unwrap_or(0.3);
        }

        if let Ok(timeout) = env::var("PROVISIONING_AI_TIMEOUT") {
            self.ai.timeout = timeout.parse().unwrap_or(30);
        }

        // Debug mode
        if let Ok(debug) = env::var("PROVISIONING_DEBUG") {
            self.debug = debug.parse().unwrap_or(false);
        }

        Ok(())
    }

    /// Validate the configuration
    fn validate(&self) -> Result<()> {
        // Validate provisioning path exists
        if !self.provisioning_path.exists() {
            return Err(anyhow::anyhow!(
                "Provisioning path does not exist: {}",
                self.provisioning_path.display()
            ));
        }

        // Check if the main provisioning script exists
        let provisioning_script = self.provisioning_path.join("core/nulib/provisioning");
        if !provisioning_script.exists() {
            return Err(anyhow::anyhow!(
                "Provisioning script not found: {}",
                provisioning_script.display()
            ));
        }

        // Validate AI configuration if enabled
        if self.ai.enabled {
            if self.ai.api_key.is_none() {
                tracing::warn!(
                    "AI is enabled but no API key found for provider: {}",
                    self.ai.provider
                );
            }

            if self.ai.temperature < 0.0 || self.ai.temperature > 1.0 {
                return Err(anyhow::anyhow!(
                    "AI temperature must be between 0.0 and 1.0, got: {}",
                    self.ai.temperature
                ));
            }
        }

        Ok(())
    }

    /// Get the provisioning command path
    pub fn provisioning_command(&self) -> PathBuf {
        self.provisioning_path.join("core/nulib/provisioning")
    }

    /// Check if AI is available
    pub fn is_ai_available(&self) -> bool {
        self.ai.enabled && self.ai.api_key.is_some()
    }
}