package com.miniabs;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.Writer;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashSet;
import java.util.List;

import org.json.JSONObject;

import android.content.Context;
import android.os.Environment;

/** Downloaded episodes live on the SD card: <id>.<ext> plus <id>.json with the episode details. */
final class Downloads {
    private Downloads() {
    }

    private static HashSet<String> ids;

    static File dir(Context c) throws IOException {
        if (!Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())) {
            throw new IOException("Non hai tarxeta SD dispoñible. Insírea ou desconéctaa do USB para descargar.");
        }
        File d = c.getExternalFilesDir(Environment.DIRECTORY_PODCASTS);
        if (d == null) throw new IOException("Non se pode usar a tarxeta SD.");
        if (!d.exists() && !d.mkdirs()) throw new IOException("Non se pode crear un cartafol na tarxeta SD.");
        File nomedia = new File(d, ".nomedia");
        if (!nomedia.exists()) {
            try {
                nomedia.createNewFile();
            } catch (IOException ignored) {
            }
        }
        return d;
    }

    static File audio(Context c, Episode e) {
        try {
            File f = new File(dir(c), e.id + e.ext);
            return f.exists() && f.length() > 0 ? f : null;
        } catch (IOException ex) {
            return null;
        }
    }

    static synchronized boolean has(Context c, String epId) {
        if (ids == null) scan(c);
        return ids.contains(epId);
    }

    /** Reads the download folder and returns saved episodes, newest first. */
    static synchronized List<Episode> list(Context c) {
        List<Episode> out = new ArrayList<Episode>();
        HashSet<String> found = new HashSet<String>();
        try {
            File[] files = dir(c).listFiles();
            if (files != null) {
                for (File f : files) {
                    if (!f.getName().endsWith(".json")) continue;
                    try {
                        Episode e = Episode.fromStored(new JSONObject(readFile(f)));
                        if (audio(c, e) != null) {
                            out.add(e);
                            found.add(e.id);
                        }
                    } catch (Exception ignored) {
                    }
                }
            }
        } catch (IOException ignored) {
        }
        ids = found;
        Collections.sort(out, new Comparator<Episode>() {
            public int compare(Episode a, Episode b) {
                return a.published == b.published ? 0 : (a.published > b.published ? -1 : 1);
            }
        });
        return out;
    }

    static synchronized void scan(Context c) {
        list(c);
    }

    static synchronized void saved(Context c, Episode e) throws IOException {
        Writer w = new OutputStreamWriter(new FileOutputStream(new File(dir(c), e.id + ".json")), "UTF-8");
        try {
            w.write(e.toJson().toString());
        } finally {
            w.close();
        }
        if (ids == null) scan(c);
        ids.add(e.id);
    }

    static synchronized void delete(Context c, Episode e) {
        try {
            File d = dir(c);
            new File(d, e.id + e.ext).delete();
            new File(d, e.id + ".json").delete();
            new File(d, e.id + ".part").delete();
        } catch (IOException ignored) {
        }
        if (ids != null) ids.remove(e.id);
        App.forgetLocal(c, e.id);
    }

    static synchronized int deleteAll(Context c) {
        int n = 0;
        for (Episode e : list(c)) {
            delete(c, e);
            n++;
        }
        try {
            File[] parts = dir(c).listFiles();
            if (parts != null) for (File f : parts) if (f.getName().endsWith(".part")) f.delete();
        } catch (IOException ignored) {
        }
        return n;
    }

    private static String readFile(File f) throws IOException {
        Reader r = new InputStreamReader(new FileInputStream(f), "UTF-8");
        try {
            StringBuilder sb = new StringBuilder();
            char[] b = new char[2048];
            int n;
            while ((n = r.read(b)) > 0) sb.append(b, 0, n);
            return sb.toString();
        } finally {
            r.close();
        }
    }
}