package com.miniabs;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.util.ArrayList;
import java.util.List;

import org.json.JSONObject;

import android.app.IntentService;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.net.wifi.WifiManager;
import android.os.PowerManager;

/** Downloads episodes one at a time to the SD card, resuming partial files. */
public class DownloadService extends IntentService {
    private static final int NOTIF_ID = 2;

    private static final List<Episode> queue = new ArrayList<Episode>();
    static volatile Episode current;
    static volatile int percent;
    static volatile String lastError;
    private static volatile String cancelId;

    public DownloadService() {
        super("MiniABS downloads");
    }

    static void enqueue(Context c, Episode e) {
        synchronized (queue) {
            if (current != null && current.id.equals(e.id)) return;
            for (Episode q : queue) if (q.id.equals(e.id)) return;
            queue.add(e);
        }
        lastError = null;
        c.startService(new Intent(c, DownloadService.class).putExtra("ep", e.toJson().toString()));
    }

    static void cancel(String epId) {
        synchronized (queue) {
            for (int i = queue.size() - 1; i >= 0; i--) if (queue.get(i).id.equals(epId)) queue.remove(i);
        }
        Episode cur = current;
        if (cur != null && cur.id.equals(epId)) cancelId = epId;
    }

    static List<Episode> queued() {
        synchronized (queue) {
            return new ArrayList<Episode>(queue);
        }
    }

    static boolean busyWith(String epId) {
        Episode cur = current;
        if (cur != null && cur.id.equals(epId)) return true;
        synchronized (queue) {
            for (Episode q : queue) if (q.id.equals(epId)) return true;
        }
        return false;
    }

    @Override
    protected void onHandleIntent(Intent intent) {
        Episode e;
        try {
            e = Episode.fromStored(new JSONObject(intent.getStringExtra("ep")));
        } catch (Exception ex) {
            return;
        }
        synchronized (queue) {
            boolean found = false;
            for (int i = 0; i < queue.size(); i++) {
                if (queue.get(i).id.equals(e.id)) {
                    queue.remove(i);
                    found = true;
                    break;
                }
            }
            if (!found) return; // cancelled while waiting
            current = e;
        }
        percent = 0;
        cancelId = null;
        PowerManager.WakeLock wake = ((PowerManager) getSystemService(POWER_SERVICE))
                .newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "MiniABS download");
        WifiManager.WifiLock wifi = ((WifiManager) getSystemService(WIFI_SERVICE))
                .createWifiLock(WifiManager.WIFI_MODE_FULL, "MiniABS download");
        wake.acquire();
        wifi.acquire();
        try {
            download(e);
            if (e.id.equals(cancelId)) {
                Downloads.delete(this, e);
            }
        } catch (Exception ex) {
            if (!e.id.equals(cancelId)) {
                lastError = "Fallou a descarga: " + Util.describe(ex);
                notifyDone(e.title, lastError);
            }
        } finally {
            current = null;
            cancelId = null;
            stopForeground(true);
            wifi.release();
            wake.release();
        }
    }

    private void download(Episode e) throws IOException {
        if (Prefs.get(this).wifiOnly() && !Util.onWifi(this)) {
            throw new IOException("non hai wifi (Axustes: Descargar só con wifi)");
        }
        File dir = Downloads.dir(this);
        if (Downloads.audio(this, e) != null) {
            Downloads.saved(this, e);
            return;
        }
        if (e.ino.length() == 0) throw new IOException("este episodio non ten ficheiro de audio");
        File part = new File(dir, e.id + ".part");
        Notification n = progressNotification(e, 0);
        startForeground(NOTIF_ID, n);

        Api.ensureFresh(this, 600);
        HttpURLConnection conn = null;
        int code = 0;
        long have = part.exists() ? part.length() : 0;
        boolean refreshed = false;
        String[] urls = Api.downloadUrls(this, e);
        for (int i = 0; i < urls.length; i++) {
            conn = Api.open(this, urls[i], "GET");
            conn.setReadTimeout(60000);
            if (have > 0) conn.setRequestProperty("Range", "bytes=" + have + "-");
            code = Api.responseCode(conn);
            if (code == 401 && !refreshed && Prefs.get(this).canRefresh()) {
                conn.disconnect();
                Api.refresh(this, true);
                refreshed = true;
                urls = Api.downloadUrls(this, e);
                i--;
                continue;
            }
            if (code == 200 || code == 206) break;
            conn.disconnect();
            if (code == 416 && have > 0) { // stale partial file: start over
                part.delete();
                have = 0;
                i--;
                continue;
            }
            if (code != 404 && code != 403) break;
        }
        if (code != 200 && code != 206) {
            if (code == 401) throw new Api.AuthException("a sesión caducou; inicia sesión de novo");
            if (code == 403) throw new IOException("a túa conta non ten permiso para descargar");
            throw new Api.ApiException(code, "");
        }
        try {
            boolean append = code == 206 && have > 0;
            if (!append) have = 0;
            long len = conn.getContentLength();
            long total = len > 0 ? have + len : (e.size > 0 ? e.size : -1);
            InputStream in = conn.getInputStream();
            OutputStream out = new FileOutputStream(part, append);
            try {
                byte[] buf = new byte[16384];
                long done = have, lastUi = 0;
                int r;
                while ((r = in.read(buf)) > 0) {
                    if (e.id.equals(cancelId)) return;
                    out.write(buf, 0, r);
                    done += r;
                    long now = System.currentTimeMillis();
                    if (now - lastUi > 1500) {
                        lastUi = now;
                        percent = total > 0 ? (int) (done * 100 / total) : 0;
                        n = progressNotification(e, percent);
                        nm().notify(NOTIF_ID, n);
                    }
                }
            } finally {
                out.close();
                in.close();
            }
        } finally {
            conn.disconnect();
        }
        if (e.id.equals(cancelId)) return;
        File dest = new File(dir, e.id + e.ext);
        if (!part.renameTo(dest)) throw new IOException("non se puido gardar o ficheiro");
        Downloads.saved(this, e);
        percent = 100;
    }

    private NotificationManager nm() {
        return (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
    }

    private PendingIntent openApp() {
        Intent i = new Intent(this, HomeActivity.class).putExtra("tab", HomeActivity.TAB_SAVED)
                .addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        return PendingIntent.getActivity(this, 1, i, PendingIntent.FLAG_UPDATE_CURRENT);
    }

    private Notification progressNotification(Episode e, int pct) {
        Notification n = new Notification(android.R.drawable.stat_sys_download, null, System.currentTimeMillis());
        n.flags |= Notification.FLAG_ONGOING_EVENT | Notification.FLAG_ONLY_ALERT_ONCE;
        int left;
        synchronized (queue) {
            left = queue.size();
        }
        String text = "Descargando " + pct + " %" + (left > 0 ? " · " + left + " máis na cola" : "");
        n.setLatestEventInfo(this, e.title, text, openApp());
        return n;
    }

    private void notifyDone(String title, String text) {
        Notification n = new Notification(android.R.drawable.stat_notify_error, text, System.currentTimeMillis());
        n.flags |= Notification.FLAG_AUTO_CANCEL;
        n.setLatestEventInfo(this, title, text, openApp());
        nm().notify(3, n);
    }
}