//! JSONL command-line harness for running a peer without the Tauri GUI.

use std::{
    collections::{HashMap, HashSet},
    ffi::OsString,
    io::Write as _,
    net::SocketAddr,
    path::{Path, PathBuf},
    sync::{Arc, Mutex},
    time::Duration,
};

use eyre::Context;
use lanspread_compat::eti::get_games;
use lanspread_db::db::{Game, GameFileDescription};
use lanspread_peer::{
    ActiveOperation,
    ActiveOperationKind,
    InstallOperation,
    PeerCommand,
    PeerEvent,
    PeerGameDB,
    PeerRuntimeComponent,
    PeerRuntimeHandle,
    PeerSnapshot,
    PeerStartOptions,
    start_peer_with_options,
};
use lanspread_peer_cli::{
    CliCommand,
    CommandEnvelope,
    ExternalUnrarUnpacker,
    FixtureSeed,
    FixtureUnpacker,
    error_line,
    event_line,
    parse_command_line,
    result_line,
    seed_fixture_game,
};
use serde_json::{Value, json};
use tokio::{
    io::{AsyncBufReadExt, BufReader},
    sync::{Notify, RwLock, mpsc},
};

#[derive(Debug)]
struct Args {
    name: String,
    games_dir: PathBuf,
    state_dir: PathBuf,
    catalog_db: Option<PathBuf>,
    fixtures: Vec<String>,
    unrar: Option<PathBuf>,
}

#[derive(Clone)]
struct JsonlWriter {
    lock: Arc<Mutex<()>>,
}

impl JsonlWriter {
    fn new() -> Self {
        Self {
            lock: Arc::new(Mutex::new(())),
        }
    }

    fn emit(&self, line: eyre::Result<String>) {
        let line = match line {
            Ok(line) => line,
            Err(err) => {
                eprintln!("failed to prepare JSONL output: {err}");
                return;
            }
        };

        let Ok(_guard) = self.lock.lock() else {
            eprintln!("failed to lock stdout");
            return;
        };

        let mut stdout = std::io::stdout().lock();
        if let Err(err) = writeln!(stdout, "{line}") {
            eprintln!("failed to write JSONL output: {err}");
        }
    }
}

#[derive(Default)]
struct CliState {
    local_peer: Option<LocalPeer>,
    local_games: Vec<Game>,
    remote_games: Vec<Game>,
    active_operations: Vec<ActiveOperation>,
    game_files: HashMap<String, Vec<GameFileDescription>>,
    unavailable_games: HashSet<String>,
}

#[derive(Clone, serde::Serialize)]
struct LocalPeer {
    peer_id: String,
    addr: String,
}

struct SharedState {
    state: RwLock<CliState>,
    peer_game_db: Arc<RwLock<PeerGameDB>>,
    catalog: Arc<RwLock<HashSet<String>>>,
    notify: Notify,
}

#[tokio::main]
async fn main() -> eyre::Result<()> {
    let args = parse_args()?;
    tokio::fs::create_dir_all(&args.games_dir).await?;
    tokio::fs::create_dir_all(&args.state_dir).await?;

    let fixture_seeds = seed_fixtures(&args.games_dir, &args.fixtures)?;
    let catalog = load_catalog(args.catalog_db.as_deref(), &fixture_seeds).await;

    let (tx_events, rx_events) = mpsc::unbounded_channel();
    let peer_game_db = Arc::new(RwLock::new(PeerGameDB::new()));
    let catalog = Arc::new(RwLock::new(catalog));
    let unpacker: Arc<dyn lanspread_peer::Unpacker> = match args.unrar {
        Some(path) => Arc::new(ExternalUnrarUnpacker::new(path)),
        None => Arc::new(FixtureUnpacker),
    };

    let mut handle = start_peer_with_options(
        args.games_dir.clone(),
        tx_events,
        peer_game_db.clone(),
        unpacker,
        catalog.clone(),
        PeerStartOptions {
            state_dir: Some(args.state_dir.clone()),
        },
    )?;
    let sender = handle.sender();

    let shared = Arc::new(SharedState {
        state: RwLock::new(CliState::default()),
        peer_game_db,
        catalog: catalog.clone(),
        notify: Notify::new(),
    });
    let writer = JsonlWriter::new();

    tokio::spawn(event_loop(rx_events, shared.clone(), writer.clone()));

    writer.emit(event_line(
        "cli-started",
        json!({
            "name": args.name,
            "games_dir": args.games_dir,
            "state_dir": args.state_dir,
            "fixtures": fixture_seeds,
        }),
    ));

    command_loop(&sender, &mut handle, shared, writer).await
}

async fn command_loop(
    sender: &mpsc::UnboundedSender<PeerCommand>,
    handle: &mut PeerRuntimeHandle,
    shared: Arc<SharedState>,
    writer: JsonlWriter,
) -> eyre::Result<()> {
    let stdin = BufReader::new(tokio::io::stdin());
    let mut lines = stdin.lines();

    while let Some(line) = lines.next_line().await? {
        if line.trim().is_empty() {
            continue;
        }

        let envelope = match parse_command_line(&line) {
            Ok(envelope) => envelope,
            Err(err) => {
                writer.emit(error_line(&None, None, &err.to_string()));
                continue;
            }
        };

        let command_name = envelope.command.name();
        match handle_command(&envelope, sender, handle, &shared).await {
            Ok(data) => {
                writer.emit(result_line(&envelope.request_id, command_name, data));
                if matches!(envelope.command, CliCommand::Shutdown) {
                    break;
                }
            }
            Err(err) => {
                writer.emit(error_line(
                    &envelope.request_id,
                    Some(command_name),
                    &err.to_string(),
                ));
            }
        }
    }

    Ok(())
}

async fn handle_command(
    envelope: &CommandEnvelope,
    sender: &mpsc::UnboundedSender<PeerCommand>,
    handle: &mut PeerRuntimeHandle,
    shared: &Arc<SharedState>,
) -> eyre::Result<Value> {
    match &envelope.command {
        CliCommand::Status => status(shared).await,
        CliCommand::ListPeers => list_peers(shared).await,
        CliCommand::ListGames => list_games(shared).await,
        CliCommand::SetGameDir { path } => {
            sender.send(PeerCommand::SetGameDir(path.clone()))?;
            Ok(json!({"queued": true, "path": path}))
        }
        CliCommand::Download {
            game_id,
            install_after_download,
        } => {
            ensure_catalog_game(shared, game_id).await?;
            ensure_no_active_operation(shared, game_id).await?;
            let files = game_files_for_download(sender, shared, game_id).await?;
            sender.send(PeerCommand::DownloadGameFilesWithOptions {
                id: game_id.clone(),
                file_descriptions: files,
                install_after_download: *install_after_download,
            })?;
            Ok(json!({"queued": true, "game_id": game_id, "install": install_after_download}))
        }
        CliCommand::Install { game_id } => {
            ensure_catalog_game(shared, game_id).await?;
            ensure_no_active_operation(shared, game_id).await?;
            sender.send(PeerCommand::InstallGame {
                id: game_id.clone(),
            })?;
            Ok(json!({"queued": true, "game_id": game_id}))
        }
        CliCommand::Uninstall { game_id } => {
            ensure_catalog_game(shared, game_id).await?;
            ensure_no_active_operation(shared, game_id).await?;
            sender.send(PeerCommand::UninstallGame {
                id: game_id.clone(),
            })?;
            Ok(json!({"queued": true, "game_id": game_id}))
        }
        CliCommand::WaitPeers { count, timeout } => wait_peers(shared, *count, *timeout).await,
        CliCommand::Connect { addr } => {
            ensure_not_self_connect(shared, *addr).await?;
            sender.send(PeerCommand::ConnectPeer(*addr))?;
            Ok(json!({"queued": true, "addr": addr.to_string()}))
        }
        CliCommand::Shutdown => {
            handle.shutdown();
            tokio::time::timeout(Duration::from_secs(5), handle.wait_stopped())
                .await
                .wrap_err("timed out waiting for peer runtime shutdown")?;
            Ok(json!({"stopped": true}))
        }
    }
}

async fn status(shared: &SharedState) -> eyre::Result<Value> {
    let state = shared.state.read().await;
    let peer_count = shared.peer_game_db.read().await.peer_snapshots().len();
    Ok(json!({
        "local_peer": state.local_peer.clone(),
        "peer_count": peer_count,
        "local_games": state.local_games.len(),
        "remote_games": state.remote_games.len(),
        "active_operations": active_operations_json(&state.active_operations),
    }))
}

async fn list_peers(shared: &SharedState) -> eyre::Result<Value> {
    let peers = shared.peer_game_db.read().await.peer_snapshots();
    Ok(json!({ "peers": peer_snapshots_json(&peers) }))
}

async fn list_games(shared: &SharedState) -> eyre::Result<Value> {
    let state = shared.state.read().await;
    let catalog = shared.catalog.read().await.clone();
    let remote = shared
        .peer_game_db
        .read()
        .await
        .get_all_games()
        .into_iter()
        .filter(|game| catalog.contains(&game.id))
        .collect::<Vec<_>>();
    Ok(json!({
        "local": state.local_games.clone(),
        "remote": remote,
        "active_operations": active_operations_json(&state.active_operations),
    }))
}

async fn ensure_catalog_game(shared: &SharedState, game_id: &str) -> eyre::Result<()> {
    if shared.catalog.read().await.contains(game_id) {
        return Ok(());
    }

    eyre::bail!("game {game_id} is not in the local catalog");
}

async fn ensure_no_active_operation(shared: &SharedState, game_id: &str) -> eyre::Result<()> {
    let state = shared.state.read().await;
    if state
        .active_operations
        .iter()
        .any(|operation| operation.id == game_id)
    {
        eyre::bail!("operation already in progress for game {game_id}");
    }

    Ok(())
}

async fn ensure_not_self_connect(shared: &SharedState, addr: SocketAddr) -> eyre::Result<()> {
    let state = shared.state.read().await;
    if state
        .local_peer
        .as_ref()
        .is_some_and(|peer| peer.addr == addr.to_string())
    {
        eyre::bail!("cannot connect peer to itself at {addr}");
    }

    Ok(())
}

async fn wait_peers(shared: &SharedState, count: usize, timeout: Duration) -> eyre::Result<Value> {
    let wait = async {
        loop {
            let peer_count = shared.peer_game_db.read().await.peer_snapshots().len();
            if peer_count >= count {
                return peer_count;
            }
            shared.notify.notified().await;
        }
    };

    let peer_count = tokio::time::timeout(timeout, wait)
        .await
        .wrap_err("timed out waiting for peers")?;
    Ok(json!({"peer_count": peer_count}))
}

async fn game_files_for_download(
    sender: &mpsc::UnboundedSender<PeerCommand>,
    shared: &SharedState,
    game_id: &str,
) -> eyre::Result<Vec<GameFileDescription>> {
    {
        let mut state = shared.state.write().await;
        if let Some(files) = state.game_files.get(game_id).cloned() {
            return Ok(files);
        }
        state.unavailable_games.remove(game_id);
    }

    sender.send(PeerCommand::GetGame(game_id.to_string()))?;
    let wait = async {
        loop {
            let state = shared.state.read().await;
            if let Some(files) = state.game_files.get(game_id).cloned() {
                return Ok(files);
            }
            if state.unavailable_games.contains(game_id) {
                eyre::bail!("no peers have game {game_id}");
            }
            drop(state);
            shared.notify.notified().await;
        }
    };

    tokio::time::timeout(Duration::from_secs(10), wait)
        .await
        .wrap_err("timed out waiting for game file details")?
}

async fn event_loop(
    mut rx_events: mpsc::UnboundedReceiver<PeerEvent>,
    shared: Arc<SharedState>,
    writer: JsonlWriter,
) {
    while let Some(event) = rx_events.recv().await {
        let (event_name, data) = update_state_from_event(&shared, event).await;
        writer.emit(event_line(event_name, data));
        shared.notify.notify_waiters();
    }
}

async fn update_state_from_event(shared: &SharedState, event: PeerEvent) -> (&'static str, Value) {
    match event {
        PeerEvent::LocalPeerReady { peer_id, addr } => {
            let local_peer = LocalPeer {
                peer_id,
                addr: addr.to_string(),
            };
            shared.state.write().await.local_peer = Some(local_peer.clone());
            ("local-peer-ready", json!(local_peer))
        }
        PeerEvent::ListGames(games) => {
            let catalog = shared.catalog.read().await.clone();
            let games = games
                .into_iter()
                .filter(|game| catalog.contains(&game.id))
                .collect::<Vec<_>>();
            shared.state.write().await.remote_games = games.clone();
            ("list-games", json!({ "games": games }))
        }
        PeerEvent::LocalLibraryChanged { games } => {
            let mut state = shared.state.write().await;
            state.local_games.clone_from(&games);
            ("local-library-changed", json!({ "games": games }))
        }
        PeerEvent::ActiveOperationsChanged { active_operations } => {
            let mut state = shared.state.write().await;
            state.active_operations.clone_from(&active_operations);
            (
                "active-operations-changed",
                json!({ "active_operations": active_operations_json(&active_operations) }),
            )
        }
        PeerEvent::GotGameFiles {
            id,
            file_descriptions,
        } => {
            shared
                .state
                .write()
                .await
                .game_files
                .insert(id.clone(), file_descriptions.clone());
            (
                "got-game-files",
                json!({"game_id": id, "file_descriptions": file_descriptions}),
            )
        }
        PeerEvent::DownloadGameFilesBegin { id } => ("download-begin", json!({"game_id": id})),
        PeerEvent::DownloadGameFileChunkFinished {
            id,
            peer_addr,
            relative_path,
            offset,
            length,
        } => (
            "download-chunk-finished",
            json!({
                "game_id": id,
                "peer_addr": peer_addr.to_string(),
                "relative_path": relative_path,
                "offset": offset,
                "length": length,
            }),
        ),
        PeerEvent::DownloadGameFilesFinished { id } => game_id_event("download-finished", id),
        PeerEvent::DownloadGameFilesFailed { id } => game_id_event("download-failed", id),
        PeerEvent::DownloadGameFilesAllPeersGone { id } => game_id_event("download-peers-gone", id),
        PeerEvent::InstallGameBegin { id, operation } => (
            "install-begin",
            json!({"game_id": id, "operation": install_operation_name(operation)}),
        ),
        PeerEvent::InstallGameFinished { id } => game_id_event("install-finished", id),
        PeerEvent::InstallGameFailed { id } => game_id_event("install-failed", id),
        PeerEvent::UninstallGameBegin { id } => game_id_event("uninstall-begin", id),
        PeerEvent::UninstallGameFinished { id } => game_id_event("uninstall-finished", id),
        PeerEvent::UninstallGameFailed { id } => game_id_event("uninstall-failed", id),
        PeerEvent::RemoveDownloadedGameBegin { id } => game_id_event("remove-download-begin", id),
        PeerEvent::RemoveDownloadedGameFinished { id } => {
            game_id_event("remove-download-finished", id)
        }
        PeerEvent::RemoveDownloadedGameFailed { id } => game_id_event("remove-download-failed", id),
        PeerEvent::NoPeersHaveGame { id } => no_peers_event(shared, id).await,
        PeerEvent::PeerConnected(addr) => ("peer-connected", peer_addr_json(addr)),
        PeerEvent::PeerDisconnected(addr) => ("peer-disconnected", peer_addr_json(addr)),
        PeerEvent::PeerDiscovered(addr) => ("peer-discovered", peer_addr_json(addr)),
        PeerEvent::PeerLost(addr) => ("peer-lost", peer_addr_json(addr)),
        PeerEvent::PeerCountUpdated(count) => ("peer-count-updated", json!({"count": count})),
        PeerEvent::RuntimeFailed { component, error } => (
            "runtime-failed",
            json!({"component": runtime_component_name(component), "error": error}),
        ),
    }
}

fn game_id_event(kind: &'static str, id: String) -> (&'static str, Value) {
    (kind, json!({"game_id": id}))
}

async fn no_peers_event(shared: &SharedState, id: String) -> (&'static str, Value) {
    shared
        .state
        .write()
        .await
        .unavailable_games
        .insert(id.clone());
    game_id_event("no-peers-have-game", id)
}

fn peer_addr_json(addr: SocketAddr) -> Value {
    json!({"addr": addr.to_string()})
}

fn active_operations_json(active_operations: &[ActiveOperation]) -> Vec<Value> {
    active_operations
        .iter()
        .map(|operation| {
            json!({
                "game_id": operation.id.clone(),
                "operation": active_operation_name(operation.operation),
            })
        })
        .collect()
}

fn peer_snapshots_json(peers: &[PeerSnapshot]) -> Vec<Value> {
    peers
        .iter()
        .map(|peer| {
            json!({
                "peer_id": peer.peer_id.clone(),
                "addr": peer.addr.to_string(),
                "library_rev": peer.library_rev,
                "library_digest": peer.library_digest,
                "features": peer.features.clone(),
                "game_count": peer.game_count,
                "games": peer.games.clone(),
            })
        })
        .collect()
}

fn active_operation_name(operation: ActiveOperationKind) -> &'static str {
    (&operation).into()
}

fn install_operation_name(operation: InstallOperation) -> &'static str {
    (&operation).into()
}

fn runtime_component_name(component: PeerRuntimeComponent) -> &'static str {
    (&component).into()
}

fn seed_fixtures(game_dir: &Path, fixtures: &[String]) -> eyre::Result<Vec<FixtureSeed>> {
    fixtures
        .iter()
        .map(|fixture| seed_fixture_game(game_dir, fixture))
        .collect()
}

async fn load_catalog(catalog_db: Option<&Path>, fixtures: &[FixtureSeed]) -> HashSet<String> {
    let mut catalog = HashSet::new();
    if let Some(path) = catalog_db
        && path.exists()
    {
        match get_games(path).await {
            Ok(games) => catalog.extend(games.into_iter().map(|game| game.game_id)),
            Err(err) => eprintln!("failed to load catalog db {}: {err}", path.display()),
        }
    }

    catalog.extend(fixtures.iter().map(|seed| seed.game_id.clone()));
    catalog
}

fn parse_args() -> eyre::Result<Args> {
    let mut args = std::env::args_os().skip(1);
    let mut parsed = Args {
        name: "peer".to_string(),
        games_dir: PathBuf::from("games"),
        state_dir: PathBuf::from("state"),
        catalog_db: default_catalog_db(),
        fixtures: Vec::new(),
        unrar: None,
    };

    while let Some(arg) = args.next() {
        match arg.to_str() {
            Some("--help" | "-h") => {
                print_help();
                std::process::exit(0);
            }
            Some("--name") => parsed.name = next_string(&mut args, "--name")?,
            Some("--games-dir") => parsed.games_dir = next_path(&mut args, "--games-dir")?,
            Some("--state-dir") => parsed.state_dir = next_path(&mut args, "--state-dir")?,
            Some("--catalog-db") => parsed.catalog_db = Some(next_path(&mut args, "--catalog-db")?),
            Some("--fixture") => parsed.fixtures.push(next_string(&mut args, "--fixture")?),
            Some("--unrar") => parsed.unrar = Some(next_path(&mut args, "--unrar")?),
            Some(other) => eyre::bail!("unknown argument: {other}"),
            None => eyre::bail!("argument is not valid UTF-8: {arg:?}"),
        }
    }

    Ok(parsed)
}

fn default_catalog_db() -> Option<PathBuf> {
    [
        PathBuf::from("/app/game.db"),
        PathBuf::from("crates/lanspread-tauri-deno-ts/src-tauri/game.db"),
    ]
    .into_iter()
    .find(|path| path.exists())
}

fn next_string(args: &mut impl Iterator<Item = OsString>, flag: &str) -> eyre::Result<String> {
    args.next()
        .ok_or_else(|| eyre::eyre!("{flag} requires a value"))?
        .into_string()
        .map_err(|value| eyre::eyre!("{flag} value is not valid UTF-8: {value:?}"))
}

fn next_path(args: &mut impl Iterator<Item = OsString>, flag: &str) -> eyre::Result<PathBuf> {
    Ok(PathBuf::from(next_string(args, flag)?))
}

fn print_help() {
    eprintln!(
        "usage: lanspread-peer-cli [--name NAME] [--games-dir PATH] [--state-dir PATH] \\
         [--catalog-db PATH] [--fixture GAME_ID] [--unrar PATH]\n\
         Reads JSONL commands on stdin and writes result/event/error JSONL on stdout."
    );
}