mod cursor;
mod healthcheck;
mod output;
mod server;
mod update_check;

use clap::Parser;
use fff::file_picker::FilePicker;
use fff::frecency::FrecencyTracker;
use fff::{FFFMode, SharedFilePicker, SharedFrecency};
use git2::Repository;
use mimalloc::MiMalloc;
use rmcp::{ServiceExt, transport::stdio};
use server::FffServer;

#[global_allocator]
static GLOBAL: MiMalloc = MiMalloc;

pub const MCP_INSTRUCTIONS: &str = concat!(
    "FFF is a fast file finder with frecency-ranked results (frequent/recent files first, git-dirty files boosted).\n",
    "\n",
    "## Which Tool Should I Use?\n",
    "\n",
    "- **grep**: DEFAULT tool. Searches file CONTENTS -- definitions, usage, patterns. Use when you have a specific name or pattern.\n",
    "- **find_files**: Explores which files/modules exist for a topic. Use when you DON'T have a specific identifier or LOOKING FOR A FILE.\n",
    "- **multi_grep**: OR logic across multiple patterns. Use for case variants (e.g. ['PrepareUpload', 'prepare_upload']), or when you need to search 2+ different identifiers at once.\n",
    "\n",
    "## Core Rules\n",
    "\n",
    "### 1. Search BARE IDENTIFIERS only\n",
    "Grep matches single lines. Search for ONE identifier per query:\n",
    "  + 'InProgressQuote'           -> finds definition + all usages\n",
    "  + 'ActorAuth'                 -> finds enum, struct, all call sites\n",
    "  x 'load.*metadata.*InProgressQuote' -> regex spanning multiple tokens, 0 results\n",
    "  x 'ctx.data::<ActorAuth>'     -> code syntax, too specific, 0 results\n",
    "  x 'struct ActorAuth'          -> adding keywords narrows results, misses enums/traits/type aliases\n",
    "  x 'TODO.*#\\d+'               -> complex regex, use simple 'TODO' then filter visually\n",
    "\n",
    "### 2. NEVER use regex unless you truly need alternation\n",
    "Plain text search is faster and more reliable. Regex patterns like `.*`, `\\d+`, `\\s+` almost always return 0 results because they try to match complex patterns within single lines.\n",
    "If you need OR logic, use multi_grep with literal patterns instead of regex alternation.\n",
    "\n",
    "### 3. Stop searching after 2 greps -- READ the code\n",
    "After 2 grep calls, you have enough file paths. Read the top result to understand the code.\n",
    "Do NOT keep grepping with variations. More greps != better understanding.\n",
    "\n",
    "### 4. Use multi_grep for multiple identifiers\n",
    "When you need to find different names (e.g. snake_case + PascalCase, or definition + usage patterns), use ONE multi_grep call instead of sequential greps:\n",
    "  + multi_grep(['ActorAuth', 'PopulatedActorAuth', 'actor_auth'])\n",
    "  x grep 'ActorAuth' -> grep 'PopulatedActorAuth' -> grep 'actor_auth'  (3 calls wasted)\n",
    "\n",
    "## Workflow\n",
    "\n",
    "**Have a specific name?** -> grep the bare identifier.\n",
    "**Need multiple name variants?** -> multi_grep with all variants in one call.\n",
    "**Exploring a topic / finding files?** -> find_files.\n",
    "**Got results?** -> Read the top file. Don't grep again.\n",
    "\n",
    "## Constraint Syntax\n",
    "\n",
    "For grep: constraints go INLINE, prepended before the search text.\n",
    "For multi_grep: constraints go in the separate 'constraints' parameter.\n",
    "\n",
    "Constraints MUST match one of these formats:\n",
    "  Extension: '*.rs', '*.{ts,tsx}'\n",
    "  Directory: 'src/', 'quotes/'\n",
    "  Filename: 'schema.rs', 'src/main.rs'\n",
    "  Exclude: '!test/', '!*.spec.ts'\n",
    "\n",
    "! Bare words without extensions are NOT constraints. 'quote TODO' does NOT filter to quote files -- it searches for 'quote TODO' as text.\n",
    "  + 'schema.rs TODO'   -> searches for 'TODO' in files schema.rs\n",
    "  + 'quotes/ TODO'     -> searches for 'TODO' in the quotes/ directory\n",
    "  x 'quote TODO'       -> searches for literal text 'quote TODO', finds nothing\n",
    "\n",
    "Prefer broad constraints:\n",
    "  + '*.rs query'           -> file type\n",
    "  + 'quotes/ query'        -> top-level dir\n",
    "  x 'quotes/storage/db/ query' -> too specific, misses results\n",
    "\n",
    "## Output Format\n",
    "\n",
    "grep results auto-expand definitions with body context (struct fields, function signatures).\n",
    "This often provides enough information WITHOUT a follow-up Read call.\n",
    "Lines marked with | are definition body context. [def] marks definition files.\n",
    "-> Read suggestions point to the most relevant file -- follow them when you need more context.\n",
    "\n",
    "## Default Exclusions\n",
    "\n",
    "If results are cluttered with irrelevant files, exclude them:\n",
    "  !tests/ - exclude tests directory\n",
    "  !*.spec.ts - exclude test files\n",
    "  !generated/ - exclude generated code",
);

/// FFF MCP Server -- a high performance & accuracy file finder for AI code assistants.
#[derive(Parser)]
#[command(name = "fff-mcp", version = concat!(env!("CARGO_PKG_VERSION"), " (", env!("FFF_GIT_HASH"), ")"))]
pub(crate) struct Args {
    /// Base directory to index. Defaults to the current working directory.
    #[arg(value_name = "PATH")]
    base_path: Option<String>,

    /// Path to the frecency database.
    #[arg(long = "frecency-db")]
    frecency_db_path: Option<String>,

    /// Path to the query history database.
    #[arg(long = "history-db")]
    #[allow(dead_code)]
    history_db_path: Option<String>,

    /// Path-shape hint for per-session log files.
    /// Each fff-mcp startup writes a fresh sibling file `<stem>+<UTC-timestamp>+<pid>.<ext>`
    #[arg(long = "log-file")]
    log_file: Option<String>,

    /// Log level (e.g. trace, debug, info, warn, error).
    #[arg(long = "log-level")]
    log_level: Option<String>,

    /// Disable automatic update checks on startup.
    #[arg(long = "no-update-check")]
    no_update_check: bool,

    /// Disable eager mmap warmup after the initial scan. Grep results will
    /// still work (files are mmap'd lazily on first access), but the first
    /// search may be slightly slower. Useful on very large repos where the
    /// warmup would consume too many kernel resources.
    #[arg(long = "no-warmup")]
    no_warmup: bool,

    /// Disable the content index built after the initial scan.
    /// This makes grep calls slower but consumes less RAM (recommended to not turn off)
    no_content_indexing: bool,

    /// Explicitly enable content indexing even when `--no-warmup` is set.
    #[arg(long = "content-indexing")]
    content_indexing: bool,

    /// Disable the background file-system watcher. Files are scanned once
    /// at startup but not monitored for changes.
    #[arg(long = "no-watch")]
    no_watch: bool,

    /// Maximum number of files whose content is kept persistently in memory.
    /// Files beyond this limit are still searchable via temporary mmaps that
    /// are released after each grep. Defaults to 30 000.
    /// Also settable via the FFF_MAX_CACHED_FILES environment variable.
    #[arg(long = "max-cached-files", env = "FFF_MAX_CACHED_FILES")]
    max_cached_files: Option<usize>,

    /// Follow symlinks during scan and watcher walks. Off by default —
    /// enabling on cyclic symlink layouts can wedge the watcher.
    #[arg(long = "follow-symlinks")]
    follow_symlinks: bool,

    /// Run a health check and print diagnostic information, then exit.
    #[arg(long = "healthcheck")]
    pub(crate) healthcheck: bool,

    /// Exit after this many seconds of inactivity. 0 = never exit.
    #[arg(
        long = "idle-timeout-secs",
        env = "FFF_MCP_IDLE_TIMEOUT_SECS",
        default_value_t = 900
    )]
    idle_timeout_secs: u64,
}

/// Resolve default paths for the log file.
/// Database paths (frecency, history) must be explicitly provided via flags.
fn resolve_defaults(args: &mut Args) {
    // Ensure parent directories exist for database paths when provided
    for path in [&args.frecency_db_path, &args.history_db_path]
        .into_iter()
        .flatten()
    {
        if let Some(parent) = std::path::Path::new(path).parent() {
            let _ = std::fs::create_dir_all(parent);
        }
    }

    if args.log_file.is_none() {
        let home = dirs_home();
        let is_windows = cfg!(target_os = "windows");
        args.log_file = Some(if is_windows {
            format!("{}\\AppData\\Local\\fff_mcp.log", home)
        } else {
            format!("{}/.cache/fff_mcp.log", home)
        });
    }
}

fn dirs_home() -> String {
    std::env::var("HOME")
        .or_else(|_| std::env::var("USERPROFILE"))
        .unwrap_or_else(|_| "/tmp".to_string())
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut args = Args::parse();
    resolve_defaults(&mut args);

    if args.healthcheck {
        return healthcheck::run_healthcheck(&args);
    }

    let log_file = args.log_file.as_deref().unwrap_or("");
    if let Err(e) = fff::log::init_tracing(log_file, args.log_level.as_deref(), None) {
        eprintln!("Warning: Failed to init tracing: {}", e);
    }

    let base_path = args.base_path.unwrap_or_else(|| {
        std::env::current_dir()
            .unwrap_or_default()
            .to_string_lossy()
            .to_string()
    });

    let base_path = match Repository::discover(&base_path) {
        Ok(repo) => {
            if let Some(workdir) = repo.workdir() {
                let git_root = workdir.to_string_lossy().to_string();
                tracing::info!("Discovered git root: {}", git_root);
                git_root
            } else {
                tracing::info!("Git repository is bare, using base path: {}", base_path);
                base_path
            }
        }
        Err(_) => {
            tracing::info!(
                "No git repository found, indexing from base path: {}",
                base_path
            );
            base_path
        }
    };

    let shared_picker = SharedFilePicker::default();
    let shared_frecency = SharedFrecency::default();
    if let Some(frecency_db_path) = args.frecency_db_path {
        match FrecencyTracker::open(&frecency_db_path) {
            Ok(tracker) => {
                let _ = shared_frecency.init(tracker);
            }
            Err(e) => {
                eprintln!("Warning: Failed to init frecency db: {}", e);
            }
        }
    }

    // Content indexing follows warmup by default (backward compat), unless
    // the user explicitly opts in via --content-indexing or out via
    // --no-content-indexing.
    let enable_content_indexing = if args.content_indexing {
        true
    } else if args.no_content_indexing {
        false
    } else {
        !args.no_warmup
    };

    // Initialize file picker (spawns background scan + watcher)
    FilePicker::new_with_shared_state(
        shared_picker.clone(),
        shared_frecency,
        fff::FilePickerOptions {
            base_path,
            enable_mmap_cache: !args.no_warmup,
            enable_content_indexing,
            watch: !args.no_watch,
            mode: FFFMode::Ai,
            cache_budget: args
                .max_cached_files
                .map(fff::ContentCacheBudget::new_for_repo),
            follow_symlinks: args.follow_symlinks,
            ..Default::default()
        },
    )
    .map_err(|e| format!("Failed to init file picker: {}", e))?;

    if !args.no_update_check {
        update_check::spawn_update_check();
    }

    // Create and start the MCP server
    let server = FffServer::new(shared_picker.clone());
    let last_activity = server.last_activity();
    let idle_timeout_secs = args.idle_timeout_secs;

    // Wait for initial scan in background — don't block server startup
    let picker_clone_for_scan = shared_picker.clone();
    tokio::task::spawn_blocking(move || {
        let start = std::time::Instant::now();
        loop {
            let is_scanning = picker_clone_for_scan
                .read()
                .ok()
                .and_then(|g| g.as_ref().map(|p| p.is_scan_active()))
                .unwrap_or(true);

            if !is_scanning {
                tracing::info!("Initial scan completed in {:?}", start.elapsed());
                break;
            }
            std::thread::sleep(std::time::Duration::from_millis(50));
        }
    });

    const STARTUP_TIMEOUT: std::time::Duration = std::time::Duration::from_secs(60);
    let service = match tokio::time::timeout(STARTUP_TIMEOUT, server.serve(stdio())).await {
        Ok(res) => res.map_err(|e| format!("Failed to start MCP server: {}", e))?,
        Err(_) => {
            return Err("MCP initialize handshake did not complete within 60s".into());
        }
    };

    if idle_timeout_secs > 0 {
        last_activity.store(
            std::time::SystemTime::now()
                .duration_since(std::time::UNIX_EPOCH)
                .map(|d| d.as_secs())
                .unwrap_or(0),
            std::sync::atomic::Ordering::Relaxed,
        );

        let last_activity_for_watchdog = last_activity.clone();
        tokio::spawn(async move {
            let tick = std::time::Duration::from_secs(60);
            loop {
                tokio::time::sleep(tick).await;
                let now = std::time::SystemTime::now()
                    .duration_since(std::time::UNIX_EPOCH)
                    .map(|d| d.as_secs())
                    .unwrap_or(0);

                let last = last_activity_for_watchdog.load(std::sync::atomic::Ordering::Relaxed);
                if now.saturating_sub(last) >= idle_timeout_secs {
                    tracing::info!(
                        "Exiting after {}s of inactivity (idle_timeout_secs={})",
                        now.saturating_sub(last),
                        idle_timeout_secs
                    );
                    std::process::exit(0);
                }
            }
        });
    }

    let picker_for_shutdown = shared_picker.clone();
    tokio::spawn(async move {
        tokio::signal::ctrl_c().await.ok();
        if let Ok(mut guard) = picker_for_shutdown.write()
            && let Some(ref mut picker) = *guard
        {
            picker.stop_background_monitor();
        }
        std::process::exit(0);
    });

    service.waiting().await?;

    if let Ok(mut guard) = shared_picker.write()
        && let Some(ref mut picker) = *guard
    {
        picker.stop_background_monitor();
    }

    Ok(())
}
