//! MCP (Model Context Protocol) server implementation for Smart Tree
//!
//! This module provides a JSON-RPC server that exposes Smart Tree's functionality
//! through the Model Context Protocol, allowing AI assistants to analyze directories.

use crate::compression_manager;
use anyhow::{Context, Result};
use serde::{Deserialize, Serialize};
use serde_json::{json, Value};
use std::io::{self, BufRead, BufReader, Write};
use std::path::{Path, PathBuf};
use std::sync::Arc;

// =============================================================================
// HEX NUMBER FORMATTING - Token-efficient numeric output for AI contexts
// =============================================================================

/// Format a number as hex or decimal based on config
/// In MCP mode, hex is default for token efficiency!
///
/// Examples:
/// - 1000 → "3E8" (hex) or "1000" (decimal)
/// - 65535 → "FFFF" (hex) or "65535" (decimal)
/// - 1048576 → "100000" (hex) or "1048576" (decimal) - 1 char saved!
#[inline]
pub fn fmt_num(n: usize, hex: bool) -> String {
    if hex {
        format!("{:X}", n)
    } else {
        n.to_string()
    }
}

/// Format a u64 as hex or decimal
#[inline]
pub fn fmt_num64(n: u64, hex: bool) -> String {
    if hex {
        format!("{:X}", n)
    } else {
        n.to_string()
    }
}

/// Format a file size with units (always human-readable but hex for raw bytes)
/// Examples with hex=true:
/// - 1048576 → "1M" (always uses SI for readability)
/// - 1234567 → "1.2M"
pub fn fmt_size(bytes: u64, hex: bool) -> String {
    if bytes < 1024 {
        if hex {
            format!("{}B", fmt_num64(bytes, true))
        } else {
            format!("{}B", bytes)
        }
    } else if bytes < 1024 * 1024 {
        format!("{:.1}K", bytes as f64 / 1024.0)
    } else if bytes < 1024 * 1024 * 1024 {
        format!("{:.1}M", bytes as f64 / (1024.0 * 1024.0))
    } else {
        format!("{:.1}G", bytes as f64 / (1024.0 * 1024.0 * 1024.0))
    }
}

/// Format a line number for display (right-aligned, 4 chars)
#[inline]
pub fn fmt_line(n: usize, hex: bool) -> String {
    if hex {
        format!("{:>4X}", n)
    } else {
        format!("{:>4}", n)
    }
}

pub mod assistant;
pub mod cache;
pub mod consciousness;
pub mod context_absorber;
mod context_tools;
pub mod dashboard_bridge;
mod enhanced_tool_descriptions;
mod git_memory_integration;
mod helpers;
mod hook_tools;
mod negotiation;
pub mod permissions;
mod proactive_assistant;
mod prompts;
mod prompts_enhanced;
mod resources;
pub mod session;
pub mod smart_background_searcher;
pub mod smart_edit;
mod smart_edit_diff_viewer;
pub mod smart_project_detector;
mod sse;
mod theme_tools;
mod tools;
mod tools_consolidated;
pub mod tools_consolidated_enhanced;
pub mod unified_watcher;
pub mod wave_memory;

// Google Drive + Gmail integration (behind feature flag)
#[cfg(feature = "google")]
pub mod google;

use assistant::*;
use cache::*;
use consciousness::*;
use negotiation::*;
use permissions::*;
#[allow(unused_imports)]
use prompts::*;
#[allow(unused_imports)]
use prompts_enhanced::*;
use resources::*;
use session::*;
use tools::*;

/// Determines if startup messages should be shown based on environment variables.
/// MCP protocol requires clean JSON-RPC on stdout - stderr messages can confuse clients.
///
/// Default: SILENT (no output) - standard MCP server behavior
///
/// To enable debug messages:
/// - MCP_DEBUG: Set to "1" or "true" to show startup messages
/// - ST_MCP_VERBOSE: Set to "1" or "true" to show startup messages
///
/// Returns true only if explicitly enabled.
fn should_show_startup_messages() -> bool {
    use std::env;

    // Only show messages if explicitly enabled
    if let Ok(val) = env::var("MCP_DEBUG") {
        if val == "1" || val.to_lowercase() == "true" {
            return true;
        }
    }

    if let Ok(val) = env::var("ST_MCP_VERBOSE") {
        if val == "1" || val.to_lowercase() == "true" {
            return true;
        }
    }

    // Default: silent (standard MCP server behavior)
    false
}

/// MCP server implementation
pub struct McpServer {
    context: Arc<McpContext>,
    consciousness: Arc<tokio::sync::Mutex<ConsciousnessManager>>,
}

/// Shared context for MCP handlers
#[derive(Clone)]
pub struct McpContext {
    /// Cache for analysis results
    pub cache: Arc<AnalysisCache>,
    /// Server configuration
    pub config: Arc<McpConfig>,
    /// Permission cache
    pub permissions: Arc<tokio::sync::Mutex<PermissionCache>>,
    /// Session manager for compression negotiation
    pub sessions: Arc<SessionManager>,
    /// Intelligent assistant for helpful recommendations
    pub assistant: Arc<McpAssistant>,
    /// Consciousness persistence manager
    pub consciousness: Arc<tokio::sync::Mutex<ConsciousnessManager>>,
    /// Optional bridge to web dashboard for real-time activity visualization
    pub dashboard_bridge: Option<dashboard_bridge::DashboardBridge>,
    /// Session "current path": the last directory an agent worked in.
    ///
    /// Relative paths (and `.`) in tool arguments are resolved against this,
    /// and it is updated after each call so an agent can omit the path on
    /// follow-up calls. Initialized to the process working directory.
    pub cwd: Arc<std::sync::Mutex<PathBuf>>,
}

/// MCP server configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct McpConfig {
    /// Enable caching
    pub cache_enabled: bool,
    /// Cache TTL in seconds
    pub cache_ttl: u64,
    /// Maximum cache size in bytes
    pub max_cache_size: usize,
    /// Allowed paths for security
    pub allowed_paths: Vec<PathBuf>,
    /// Blocked paths for security
    pub blocked_paths: Vec<PathBuf>,
    /// Use consolidated tools (reduces tool count from 50+ to ~15)
    pub use_consolidated_tools: bool,
    /// Use hexadecimal for all numbers (saves tokens!)
    /// Line 1000 → 3E8, size 1048576 → 100000
    pub hex_numbers: bool,
}

impl Default for McpConfig {
    fn default() -> Self {
        Self {
            cache_enabled: true,
            cache_ttl: 300,                    // 5 minutes
            max_cache_size: 100 * 1024 * 1024, // 100MB
            allowed_paths: vec![],
            blocked_paths: vec![
                PathBuf::from("/etc"),
                PathBuf::from("/sys"),
                PathBuf::from("/proc"),
            ],
            use_consolidated_tools: true, // Default to consolidated for Cursor compatibility
            hex_numbers: true,            // Default to hex for token efficiency!
        }
    }
}

/// JSON-RPC request structure
#[derive(Debug, Deserialize)]
struct JsonRpcRequest {
    #[allow(dead_code)]
    jsonrpc: String,
    method: String,
    params: Option<Value>,
    id: Option<Value>,
}

/// JSON-RPC response structure
#[derive(Debug, Serialize)]
struct JsonRpcResponse {
    jsonrpc: String,
    #[serde(skip_serializing_if = "Option::is_none")]
    result: Option<Value>,
    #[serde(skip_serializing_if = "Option::is_none")]
    error: Option<JsonRpcError>,
    id: Option<Value>,
}

/// JSON-RPC error structure
#[derive(Debug, Serialize)]
struct JsonRpcError {
    code: i32,
    message: String,
    #[serde(skip_serializing_if = "Option::is_none")]
    data: Option<Value>,
}

impl McpServer {
    /// Create a new MCP server
    pub fn new(config: McpConfig) -> Self {
        // Use silent constructor - MCP protocol requires clean stdout
        let consciousness = Arc::new(tokio::sync::Mutex::new(ConsciousnessManager::new_silent()));

        let context = Arc::new(McpContext {
            cache: Arc::new(AnalysisCache::new(config.cache_ttl)),
            config: Arc::new(config),
            permissions: Arc::new(tokio::sync::Mutex::new(PermissionCache::new())),
            sessions: Arc::new(SessionManager::new()),
            assistant: Arc::new(McpAssistant::new()),
            consciousness: consciousness.clone(),
            dashboard_bridge: None,
            cwd: Arc::new(std::sync::Mutex::new(
                std::env::current_dir().unwrap_or_else(|_| PathBuf::from(".")),
            )),
        });

        Self {
            context,
            consciousness,
        }
    }

    /// Run the MCP server on stdio
    pub async fn run_stdio(&self) -> Result<()> {
        let stdin = io::stdin();
        let stdout = io::stdout();
        let mut reader = BufReader::new(stdin);
        let mut stdout = stdout.lock();

        // Restore previous consciousness silently (no output that would break MCP protocol)
        {
            let mut consciousness = self.consciousness.lock().await;
            let _ = consciousness.restore_silent(); // Silent restore, no stderr output
        }

        // MCP protocol requires clean JSON-RPC on stdout
        // All debug/info messages go to stderr, only when not in quiet mode
        // Respects environment variables: MCP_QUIET, NO_STARTUP_MESSAGES, RUST_LOG
        if should_show_startup_messages() {
            eprintln!(
                "<!-- Smart Tree MCP server v{} started -->",
                env!("CARGO_PKG_VERSION")
            );
            eprintln!("<!--   Protocol: MCP v1.0 -->");
        }

        loop {
            let mut line = String::new();
            match reader.read_line(&mut line) {
                Ok(0) => break, // EOF
                Ok(_) => {
                    let line = line.trim();
                    if line.is_empty() {
                        continue;
                    }

                    match self.handle_request(line).await {
                        Ok(response) => {
                            // Only write response if it's not empty (notifications return empty)
                            if !response.is_empty() {
                                writeln!(stdout, "{}", response)?;
                                stdout.flush()?;
                            }
                        }
                        Err(e) => {
                            if should_show_startup_messages() {
                                eprintln!("Error handling request: {e}");
                            }
                            let error_response = json!({
                                "jsonrpc": "2.0",
                                "error": {
                                    "code": -32603,
                                    "message": e.to_string()
                                },
                                "id": null
                            });
                            writeln!(stdout, "{}", error_response)?;
                            stdout.flush()?;
                        }
                    }
                }
                Err(e) => {
                    if should_show_startup_messages() {
                        eprintln!("Error reading input: {e}");
                    }
                    break;
                }
            }
        }

        if should_show_startup_messages() {
            eprintln!("Smart Tree MCP server stopped");
        }
        Ok(())
    }

    /// Handle a single JSON-RPC request
    async fn handle_request(&self, request_str: &str) -> Result<String> {
        // Parse JSON-RPC request
        let request: JsonRpcRequest =
            serde_json::from_str(request_str).context("Failed to parse JSON-RPC request")?;

        // Check for compression support in every request
        if let Some(ref params) = request.params {
            compression_manager::check_client_compression_support(params);
        }

        // Check if this is a notification (no id field)
        let is_notification = request.id.is_none();

        // Handle notifications that don't expect responses
        if is_notification && request.method == "notifications/initialized" {
            // Just acknowledge receipt, don't send response
            if should_show_startup_messages() {
                eprintln!("Received notification: notifications/initialized");
            }
            return Ok(String::new()); // Return empty string to skip response
        }

        // Handle logging/setLevel notification
        if is_notification && request.method == "logging/setLevel" {
            // Extract log level from params if provided
            if should_show_startup_messages() {
                let level = request
                    .params
                    .as_ref()
                    .and_then(|p| p.get("level"))
                    .and_then(|v| v.as_str())
                    .unwrap_or("unspecified");
                eprintln!("Received logging/setLevel notification: level={}", level);
            }
            return Ok(String::new()); // Return empty string to skip response
        }

        // Route the request
        let result = match request.method.as_str() {
            "initialize" => {
                // Use session-aware initialization if ST_SESSION_AWARE is set
                if std::env::var("ST_SESSION_AWARE").is_ok() {
                    handle_session_aware_initialize(request.params, self.context.clone()).await
                } else {
                    handle_initialize(request.params, self.context.clone()).await
                }
            }
            "session/negotiate" => {
                handle_negotiate_session(request.params, self.context.clone()).await
            }
            "tools/list" => {
                if self.context.config.use_consolidated_tools {
                    handle_consolidated_tools_list(request.params, self.context.clone()).await
                } else {
                    handle_tools_list(request.params, self.context.clone()).await
                }
            }
            "tools/call" => {
                if self.context.config.use_consolidated_tools {
                    handle_consolidated_tools_call(
                        request.params.unwrap_or(json!({})),
                        self.context.clone(),
                    )
                    .await
                } else {
                    handle_tools_call(request.params.unwrap_or(json!({})), self.context.clone())
                        .await
                }
            }
            "resources/list" => handle_resources_list(request.params, self.context.clone()).await,
            "resources/read" => {
                handle_resources_read(request.params.unwrap_or(json!({})), self.context.clone())
                    .await
            }
            "prompts/list" => {
                // Use enhanced prompts by default, fall back to legacy if needed
                prompts_enhanced::handle_prompts_list(request.params, self.context.clone()).await
            }
            "prompts/get" => {
                prompts_enhanced::handle_prompts_get(
                    request.params.unwrap_or(json!({})),
                    self.context.clone(),
                )
                .await
            }
            "notifications/cancelled" => {
                // This is also a notification but might need handling
                if is_notification {
                    if should_show_startup_messages() {
                        eprintln!("Received notification: notifications/cancelled");
                    }
                    return Ok(String::new());
                }
                handle_cancelled(request.params, self.context.clone()).await
            }
            _ => Err(anyhow::anyhow!("Method not found: {}", request.method)),
        };

        // Don't send response for notifications (they don't expect responses)
        if is_notification {
            // Log unknown notifications for debugging (only if verbose)
            if result.is_err() && should_show_startup_messages() {
                eprintln!(
                    "Received unknown notification: {} (notifications don't return errors)",
                    request.method
                );
            }
            return Ok(String::new());
        }

        // Build response for requests only
        let response = match result {
            Ok(result) => JsonRpcResponse {
                jsonrpc: "2.0".to_string(),
                result: Some(result),
                error: None,
                id: request.id,
            },
            Err(e) => JsonRpcResponse {
                jsonrpc: "2.0".to_string(),
                result: None,
                error: Some(JsonRpcError {
                    code: -32603,
                    message: e.to_string(),
                    data: None,
                }),
                id: request.id,
            },
        };

        // Smart compress the response if needed
        let mut response_value = serde_json::to_value(&response)?;
        compression_manager::smart_compress_mcp_response(&mut response_value)?;

        Ok(serde_json::to_string(&response_value)?)
    }
}

// Handler implementations

async fn handle_initialize(params: Option<Value>, _ctx: Arc<McpContext>) -> Result<Value> {
    // Check if client supports compression from their request
    if let Some(params) = params {
        compression_manager::check_client_compression_support(&params);
    }

    // Check for updates when MCP tools initialize (non-blocking)
    let update_info = check_for_mcp_updates().await;

    // Add compression test to response
    let compression_test = compression_manager::create_compression_test();

    Ok(json!({
        "protocolVersion": "2025-06-18",
        "capabilities": {
            "tools": {
                "listChanged": false
            },
            "resources": {
                "subscribe": false,
                "listChanged": false
            },
            "prompts": {
                "listChanged": false
            },
            "logging": {}
        },
        "serverInfo": {
            "name": "smart-tree",
            "version": env!("CARGO_PKG_VERSION"),
            "vendor": "8b-is",
            "description": "Smart Tree v5 - NOW WITH COMPRESSION HINTS! 🗜️ Use compress:true for 80% smaller outputs. For massive codebases, use mode:'quantum' for 100x compression!",
            "homepage": env!("CARGO_PKG_REPOSITORY"),
            "features": [
                "quantum-compression",
                "mcp-optimization",
                "content-search",
                "streaming",
                "caching",
                "emotional-mode",
                "auto-compression-hints"
            ],
            "compression_hint": "💡 Always add compress:true to analyze tools for optimal context usage!",
            "update_info": update_info,
            "compression_test": compression_test
        }
    }))
}

/// Handle MCP notification that a request was cancelled
///
/// When an AI assistant cancels a long-running operation, we acknowledge it gracefully.
/// This helps with cleanup and prevents orphaned operations.
async fn handle_cancelled(params: Option<Value>, _ctx: Arc<McpContext>) -> Result<Value> {
    // Extract the request ID that was cancelled (if provided)
    let request_id = params
        .as_ref()
        .and_then(|p| p.get("requestId"))
        .and_then(|id| id.as_str())
        .unwrap_or("unknown");

    // Log to stderr for debugging (only if MCP_DEBUG is enabled)
    if should_show_startup_messages() {
        eprintln!("[MCP] Request cancelled: {}", request_id);
    }

    // Acknowledge the cancellation - MCP protocol expects a response
    Ok(json!({
        "acknowledged": true,
        "request_id": request_id,
        "message": "Request cancellation acknowledged"
    }))
}

/// Handle consolidated tools list request
async fn handle_consolidated_tools_list(
    _params: Option<Value>,
    _ctx: Arc<McpContext>,
) -> Result<Value> {
    // Use the enhanced tools with tips and examples
    let tools = tools_consolidated_enhanced::get_enhanced_consolidated_tools();

    // Also include a welcome message for first-time AI assistants
    let welcome = tools_consolidated_enhanced::get_welcome_message();

    Ok(json!({
        "tools": tools,
        "_welcome": welcome
    }))
}

/// Handle consolidated tools call request
async fn handle_consolidated_tools_call(params: Value, ctx: Arc<McpContext>) -> Result<Value> {
    let tool_name = params["name"]
        .as_str()
        .ok_or_else(|| anyhow::anyhow!("Missing tool name"))?;
    let args = params.get("arguments").cloned();

    // The consolidated tools already return properly formatted responses
    let result =
        tools_consolidated_enhanced::dispatch_consolidated_tool(tool_name, args, ctx).await?;

    // Global safeguard: Prevent returning massive context to the AI
    let stringified = serde_json::to_string(&result)?;
    if stringified.len() > 50_000 {
        return Ok(json!({
            "content": [{
                "type": "text",
                "text": format!("⚠️ ERROR: Tool '{}' response was too large to return ({} bytes, max 50,000). The operation succeeded, but returning the data would overwhelm your context window.\n\nPlease use the 'limit' and 'offset' parameters to paginate through the results, or narrow the search parameters.", tool_name, stringified.len())
            }]
        }));
    }

    Ok(result)
}

/// Check for updates when MCP tools initialize (non-blocking, with timeout)
async fn check_for_mcp_updates() -> Value {
    // Skip if disabled or in privacy mode
    let flags = crate::feature_flags::features();
    if flags.privacy_mode || flags.disable_external_connections {
        return json!(null);
    }

    // Skip if explicitly disabled
    if std::env::var("SMART_TREE_NO_UPDATE_CHECK").is_ok() {
        return json!(null);
    }

    // Get system info for analytics (helps decide what platforms to support)
    let platform = std::env::consts::OS;
    let arch = std::env::consts::ARCH;
    let current_version = env!("CARGO_PKG_VERSION");

    // Use tokio timeout to prevent blocking
    let timeout_duration = tokio::time::Duration::from_secs(2);

    let result = tokio::time::timeout(timeout_duration, async {
        // Build request with platform info for analytics
        let client = reqwest::Client::builder()
            .timeout(std::time::Duration::from_secs(2))
            .build()
            .ok()?;

        let api_url = std::env::var("SMART_TREE_FEEDBACK_API")
            .unwrap_or_else(|_| "https://f.8b.is".to_string());

        // Include platform info to help understand usage (Windows ARM, etc.)
        let check_url = format!(
            "{}/mcp/check?version={}&platform={}&arch={}",
            api_url, current_version, platform, arch
        );

        let response = client.get(&check_url).send().await.ok()?;

        if !response.status().is_success() {
            return None;
        }

        response.json::<Value>().await.ok()
    })
    .await;

    match result {
        Ok(Some(update_data)) => {
            // Return update info if available
            if update_data["update_available"].as_bool().unwrap_or(false) {
                json!({
                    "available": true,
                    "latest_version": update_data["latest_version"],
                    "new_features": update_data["new_features"],
                    "message": update_data["message"]
                })
            } else {
                json!({
                    "available": false,
                    "message": "You're running the latest version!"
                })
            }
        }
        _ => json!(null), // Return null if check failed or timed out
    }
}

/// Check if a path is allowed based on security configuration
pub fn is_path_allowed(path: &Path, config: &McpConfig) -> bool {
    // Check blocked paths first
    for blocked in &config.blocked_paths {
        if path.starts_with(blocked) {
            return false;
        }
    }

    // If allowed_paths is empty, allow all non-blocked paths
    if config.allowed_paths.is_empty() {
        return true;
    }

    // Otherwise, check if path is under an allowed path
    for allowed in &config.allowed_paths {
        if path.starts_with(allowed) {
            return true;
        }
    }

    false
}

/// Load MCP configuration from file or use defaults
pub fn load_config() -> Result<McpConfig> {
    let config_path = dirs::home_dir()
        .map(|d| d.join(".st_bumpers").join("mcp-config.toml"))
        .unwrap_or_else(|| PathBuf::from(".st_bumpers/mcp-config.toml"));

    if config_path.exists() {
        let config_str =
            std::fs::read_to_string(&config_path).context("Failed to read MCP config file")?;
        toml::from_str(&config_str).context("Failed to parse MCP config file")
    } else {
        Ok(McpConfig::default())
    }
}

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

    #[tokio::test]
    async fn test_logging_setlevel_notification() {
        let config = McpConfig::default();
        let server = McpServer::new(config);

        // Test logging/setLevel notification without params
        let request = r#"{"jsonrpc":"2.0","method":"logging/setLevel"}"#;
        let response = server.handle_request(request).await.unwrap();
        assert_eq!(response, "", "Notification should return empty response");

        // Test logging/setLevel notification with level parameter
        let request_with_level =
            r#"{"jsonrpc":"2.0","method":"logging/setLevel","params":{"level":"debug"}}"#;
        let response_with_level = server.handle_request(request_with_level).await.unwrap();
        assert_eq!(
            response_with_level, "",
            "Notification with params should return empty response"
        );
    }

    #[tokio::test]
    async fn test_notifications_initialized() {
        let config = McpConfig::default();
        let server = McpServer::new(config);

        // Test notifications/initialized
        let request = r#"{"jsonrpc":"2.0","method":"notifications/initialized"}"#;
        let response = server.handle_request(request).await.unwrap();
        assert_eq!(
            response, "",
            "notifications/initialized should return empty response"
        );
    }

    #[tokio::test]
    async fn test_unknown_notification() {
        let config = McpConfig::default();
        let server = McpServer::new(config);

        // Test unknown notification - should return empty response without error
        let request = r#"{"jsonrpc":"2.0","method":"notifications/unknown"}"#;
        let response = server.handle_request(request).await.unwrap();
        assert_eq!(
            response, "",
            "Unknown notification should return empty response"
        );
    }
}