use std::sync::mpsc::{self, Sender};
use std::time::Duration;

use eframe::egui;

use std::collections::HashMap;

use crate::config::Config;
use crate::countries::{get_countries, Country};
use crate::flags;
use crate::nordvpn::{self, CmdResult, Poller};
use crate::ui::country_selector::CountrySelector;

pub struct App {
    config: Config,
    countries: Vec<Country>,
    poller: Poller,
    cmd_tx: Sender<CmdResult>,
    cmd_rx: mpsc::Receiver<CmdResult>,
    /// Receives rasterized flag images from the background loader thread.
    flag_rx: mpsc::Receiver<(String, egui::ColorImage)>,
    /// Fully loaded flag textures, keyed by nordvpn_key.
    flag_textures: HashMap<String, egui::TextureHandle>,
    selector: CountrySelector,
    /// Last connect/disconnect result shown inline below the status bar.
    notification: Option<String>,
}

impl App {
    pub fn new(cc: &eframe::CreationContext<'_>) -> Self {
        let config = Config::load();
        let countries = get_countries(&config.external_app);
        let poller = Poller::new(config.external_app.clone(), config.refresh_rate);
        let (cmd_tx, cmd_rx) = mpsc::channel();

        // Kick off background flag rasterization.
        let (flag_tx, flag_rx) = mpsc::channel();
        flags::spawn_loader(flags::flag_paths(&countries), flag_tx);

        Self {
            config,
            countries,
            poller,
            cmd_tx,
            cmd_rx,
            flag_rx,
            flag_textures: HashMap::new(),
            selector: CountrySelector::default(),
            notification: None,
        }
    }

    fn spawn_connect(&self, nordvpn_key: String) {
        let app = self.config.external_app.clone();
        let tx = self.cmd_tx.clone();
        std::thread::spawn(move || {
            let _ = tx.send(nordvpn::connect(&app, &nordvpn_key));
        });
    }

    fn spawn_disconnect(&self) {
        let app = self.config.external_app.clone();
        let tx = self.cmd_tx.clone();
        std::thread::spawn(move || {
            let _ = tx.send(nordvpn::disconnect(&app));
        });
    }

}

impl eframe::App for App {
    fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
        // Upload any newly rasterized flag textures.
        while let Ok((key, image)) = self.flag_rx.try_recv() {
            let handle = ctx.load_texture(&key, image, egui::TextureOptions::LINEAR);
            self.flag_textures.insert(key, handle);
        }

        // Drain completed command results.
        while let Ok(result) = self.cmd_rx.try_recv() {
            self.notification = Some(match result {
                CmdResult::Success { output, .. } => output.trim().to_string(),
                CmdResult::Failure { cmd, message } => {
                    format!("Error running '{cmd}': {message}")
                }
            });
        }

        // Repaint often enough to stay live without busy-looping.
        ctx.request_repaint_after(Duration::from_secs(1));

        let status = self.poller.status.lock().unwrap().clone();

        // ── Status panel ────────────────────────────────────────────────────
        egui::TopBottomPanel::top("status_panel")
            .min_height(40.0)
            .show(ctx, |ui| {
                ui.add_space(4.0);
                ui.horizontal(|ui| {
                    ui.strong(&status.status);
                    if let Some(country) = &status.country {
                        ui.separator();
                        ui.label(country);
                    }
                    if let Some(ip) = &status.ip {
                        ui.separator();
                        ui.label(ip);
                    }
                    if let Some(uptime) = &status.uptime {
                        ui.separator();
                        ui.weak(uptime);
                    }
                });
                if let Some(note) = &self.notification {
                    ui.add_space(2.0);
                    ui.weak(note);
                }
                ui.add_space(4.0);
            });

        // ── Bottom bar ──────────────────────────────────────────────────────
        egui::TopBottomPanel::bottom("bottom_bar")
            .min_height(36.0)
            .show(ctx, |ui| {
                ui.add_space(4.0);
                ui.horizontal(|ui| {
                    if ui.button("Disconnect").clicked() {
                        self.notification = None;
                        self.spawn_disconnect();
                    }
                    ui.with_layout(egui::Layout::right_to_left(egui::Align::Center), |ui| {
                        if ui.button("Configure").clicked() {
                            // Phase 7
                        }
                    });
                });
            });

        // ── Left panel — country selector ───────────────────────────────────
        let panel_width = ctx.screen_rect().width() * 0.3;
        let connect_key =
            egui::SidePanel::left("country_selector")
                .exact_width(panel_width)
                .resizable(false)
                .show(ctx, |ui| {
                    self.selector.show(
                        ui,
                        &self.countries,
                        &self.config.favorites,
                        status.country.as_deref(),
                        &self.flag_textures,
                    )
                })
                .inner;

        if let Some(key) = connect_key {
            self.notification = None;
            self.spawn_connect(key);
        }

        // ── Central panel — world map placeholder ───────────────────────────
        egui::CentralPanel::default().show(ctx, |ui| {
            ui.centered_and_justified(|ui| {
                ui.weak("World map — Phase 5");
            });
        });
    }
}