mod app;
mod domain;
mod infrastructure;
mod ui;

use std::io;
use std::sync::Arc;

use crossterm::event::{self, Event};
use crossterm::terminal::{disable_raw_mode, enable_raw_mode, EnterAlternateScreen, LeaveAlternateScreen};
use crossterm::ExecutableCommand;
use ratatui::backend::CrosstermBackend;
use ratatui::Terminal;
use tokio::sync::Mutex;

use crate::app::{App, SyncCommand};
use crate::domain::models::*;
use crate::infrastructure::api::ApiClient;
use crate::infrastructure::db::Db;
use crate::ui::{draw, AppView, NetworkStatus};

fn main() -> io::Result<()> {
    let db_path = dirs::data_dir()
        .unwrap_or_else(|| std::path::PathBuf::from("."))
        .join("task_app")
        .join("tasks.db");

    std::fs::create_dir_all(db_path.parent().unwrap()).ok();

    let db = Arc::new(Db::new(db_path.to_str().unwrap()).expect("Failed to open database"));

    enable_raw_mode()?;
    let mut stdout = io::stdout();
    stdout.execute(EnterAlternateScreen)?;
    let backend = CrosstermBackend::new(stdout);
    let mut terminal = Terminal::new(backend)?;

    let api_client = Arc::new(ApiClient::new(
        std::env::var("GOOGLE_CLIENT_ID").unwrap_or_default(),
        std::env::var("GOOGLE_CLIENT_SECRET").unwrap_or_default(),
    ));

    let network_status = Arc::new(Mutex::new(NetworkStatus::Online));
    let (sync_tx, mut sync_rx) = tokio::sync::mpsc::channel::<SyncCommand>(32);

    let mut app = App::new(db.clone(), api_client.clone(), sync_tx.clone());

    let network_clone = network_status.clone();
    let db_clone = db.clone();
    let api_clone = api_client.clone();

    std::thread::spawn(move || {
        let rt = tokio::runtime::Runtime::new().unwrap();
        rt.block_on(async move {
            run_sync_engine(db_clone, api_clone, network_clone, &mut sync_rx).await;
        });
    });

    // Trigger initial sync if already authenticated
    if !app.needs_auth {
        let _ = sync_tx.try_send(SyncCommand::InitialSync);
    }

    while !app.should_quit {
        // Poll auth status (non-blocking)
        app.poll_auth();

        // Check if initial sync has loaded data into DB
        app.check_initial_load();

        terminal.draw(|frame| {
            let status = {
                let guard = network_status.blocking_lock();
                guard.clone()
            };
            app.network_status = status;

            let view = AppView {
                lists: &app.lists,
                tasks: &app.tasks,
                selected_list: app.selected_list,
                selected_task: app.selected_task,
                focus: app.focus.clone(),
                show_popup: app.show_popup.as_ref(),
                popup_input: &app.popup_input,
                popup_cursor: app.popup_cursor,
                draft_date: app.draft_date,
                network_status: &app.network_status,
                task_list_scroll: app.task_list_scroll,
                detail_scroll: app.detail_scroll,
                auth_error: app.auth_error.as_deref(),
            };
            draw(frame, view);
        })?;

        if let Event::Key(key) = event::read()? {
            app.handle_key(key);
        }
    }

    disable_raw_mode()?;
    io::stdout().execute(LeaveAlternateScreen)?;
    Ok(())
}

async fn run_sync_engine(
    db: Arc<Db>,
    api: Arc<ApiClient>,
    network_status: Arc<Mutex<NetworkStatus>>,
    rx: &mut tokio::sync::mpsc::Receiver<SyncCommand>,
) {
    let mut interval = tokio::time::interval(tokio::time::Duration::from_secs(30));

    loop {
        tokio::select! {
            _ = interval.tick() => {
                process_sync_queue(&db, &api, &network_status).await;
            }
            cmd = rx.recv() => {
                match cmd {
                    Some(SyncCommand::TriggerSync) => {
                        process_sync_queue(&db, &api, &network_status).await;
                    }
                    Some(SyncCommand::InitialSync) => {
                        run_initial_sync(&db, &api, &network_status).await;
                    }
                    Some(SyncCommand::Shutdown) | None => break,
                }
            }
        }
    }
}

async fn run_initial_sync(
    db: &Arc<Db>,
    api: &Arc<ApiClient>,
    network_status: &Arc<Mutex<NetworkStatus>>,
) {
    *network_status.lock().await = NetworkStatus::Syncing;

    match api.fetch_lists().await {
        Ok(lists) => {
            db.replace_all_lists(&lists).ok();
            for list in &lists {
                if let Ok(tasks) = api.fetch_tasks(&list.id).await {
                    db.replace_all_tasks(&list.id, &tasks).ok();
                }
            }
            *network_status.lock().await = NetworkStatus::Online;
        }
        Err(_) => {
            *network_status.lock().await = NetworkStatus::Offline;
        }
    }
}

async fn process_sync_queue(
    db: &Arc<Db>,
    api: &Arc<ApiClient>,
    network_status: &Arc<Mutex<NetworkStatus>>,
) {
    let token_available = api.load_token().await.is_some();
    if !token_available {
        *network_status.lock().await = NetworkStatus::Offline;
        return;
    }

    let items = db.drain_sync();

    if items.is_empty() {
        *network_status.lock().await = NetworkStatus::Online;
        return;
    }

    *network_status.lock().await = NetworkStatus::Syncing;

    let mut all_ok = true;
    for item in &items {
        let result = match item.action {
            SyncAction::Create => {
                let task = serde_json::from_str::<Task>(&item.payload).unwrap_or_else(|_| Task {
                    id: item.task_id.clone(),
                    list_id: item.list_id.clone(),
                    title: String::new(),
                    notes: None,
                    status: TaskStatus::NeedsAction,
                    due: None,
                    position: 0,
                });
                api.create_task(&item.list_id, &task).await
            }
            SyncAction::Update => {
                let task = serde_json::from_str::<Task>(&item.payload).unwrap_or_else(|_| Task {
                    id: item.task_id.clone(),
                    list_id: item.list_id.clone(),
                    title: String::new(),
                    notes: None,
                    status: TaskStatus::NeedsAction,
                    due: None,
                    position: 0,
                });
                api.update_task(&item.list_id, &task).await
            }
            SyncAction::Delete => {
                api.delete_task(&item.list_id, &item.task_id).await
            }
            SyncAction::Reorder => {
                api.move_task(&item.list_id, &item.task_id, None, None).await
            }
        };

        if result.is_err() {
            let _ = db.push_sync(
                item.action.clone(),
                &item.task_id,
                &item.list_id,
                &item.payload,
            );
            all_ok = false;
            break;
        }
    }

    *network_status.lock().await = if all_ok {
        NetworkStatus::Online
    } else {
        NetworkStatus::Offline
    };
}