package de.thedevstack.conversationsplus.utils;

import android.graphics.Bitmap;
import android.net.Uri;
import android.util.Base64;
import android.util.Base64OutputStream;
import android.util.Log;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.security.DigestOutputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import de.thedevstack.conversationsplus.Config;
import de.thedevstack.conversationsplus.ConversationsPlusApplication;
import de.thedevstack.conversationsplus.xmpp.pep.Avatar;

/**
 * This util provides access to saved avatars, creating avatars.
 */
public final class AvatarUtil {

    /**
     * Get the PEP Avatar.
     * TODO: Why PEP Avatar?
     * @param image the uri to the avatar's image
     * @param size the image width/height to resize to
     * @param format the format for the avatar
     * @return the avatar
     */
    public static Avatar getPepAvatar(Uri image, int size, Bitmap.CompressFormat format) {
        try {
            Avatar avatar = new Avatar();
            Bitmap bm = ImageUtil.cropCenterSquare(image, size);
            if (bm == null) {
                return null;
            }
            ByteArrayOutputStream mByteArrayOutputStream = new ByteArrayOutputStream();
            Base64OutputStream mBase64OutputSttream = new Base64OutputStream(
                    mByteArrayOutputStream, Base64.DEFAULT);
            MessageDigest digest = MessageDigest.getInstance("SHA-1");
            DigestOutputStream mDigestOutputStream = new DigestOutputStream(
                    mBase64OutputSttream, digest);
            if (!bm.compress(format, 75, mDigestOutputStream)) {
                return null;
            }
            mDigestOutputStream.flush();
            mDigestOutputStream.close();
            avatar.sha1sum = CryptoHelper.bytesToHex(digest.digest());
            avatar.image = new String(mByteArrayOutputStream.toByteArray());
            return avatar;
        } catch (NoSuchAlgorithmException e) {
            return null;
        } catch (IOException e) {
            return null;
        }
    }

    /**
     * Returns whether the avatar is cached or not.
     * @param avatar the avatar to check the existance
     * @return <code>true</code> if the file of the avatar exists, <code>false</code> otherwise
     */
    public static boolean isAvatarCached(Avatar avatar) {
        File file = new File(getAvatarPath(avatar.getFilename()));
        return file.exists();
    }

    /**
     * Saves an avatar to the file system.
     * All exceptions are silently ignored.
     * TODO: Move real saving operation to FileBackend
     * @param avatar the avatar to save
     * @return <code>true</code> if the avatar was saved successfully, <code>false</code> otherwise.
     */
    public static boolean save(Avatar avatar) {
        File file;
        if (isAvatarCached(avatar)) {
            file = new File(getAvatarPath(avatar.getFilename()));
        } else {
            String filename = getAvatarPath(avatar.getFilename());
            file = new File(filename + ".tmp");
            file.getParentFile().mkdirs();
            OutputStream os = null;
            try {
                file.createNewFile();
                os = new FileOutputStream(file);
                MessageDigest digest = MessageDigest.getInstance("SHA-1");
                digest.reset();
                DigestOutputStream mDigestOutputStream = new DigestOutputStream(os, digest);
                mDigestOutputStream.write(avatar.getImageAsBytes());
                mDigestOutputStream.flush();
                mDigestOutputStream.close();
                String sha1sum = CryptoHelper.bytesToHex(digest.digest());
                if (sha1sum.equals(avatar.sha1sum)) {
                    file.renameTo(new File(filename));
                } else {
                    Log.d(Config.LOGTAG, "sha1sum mismatch for " + avatar.owner);
                    file.delete();
                    return false;
                }
            } catch (FileNotFoundException e) {
                return false;
            } catch (IOException e) {
                return false;
            } catch (NoSuchAlgorithmException e) {
                return false;
            } finally {
                StreamUtil.close(os);
            }
        }
        avatar.size = file.length();
        return true;
    }

    /**
     * Returns the avatar for an uri.
     * @param avatar the avatar's uri
     * @param size the height/width the avatar should have
     * @return the bitmap of the uri
     */
    public static Bitmap getAvatar(String avatar, int size) {
        if (avatar == null) {
            return null;
        }
        Bitmap bm = ImageUtil.cropCenter(getAvatarUri(avatar), size, size);
        if (bm == null) {
            return null;
        }
        return bm;
    }

    /**
     * Returns the path to an avatar
     * @param avatar the name of the avatar.
     * @return the path as string
     */
    public static String getAvatarPath(String avatar) {
        return ConversationsPlusApplication.getInstance().getFilesDir().getAbsolutePath()+ "/avatars/" + avatar;
    }

    /**
     * Returns the path to an avatar as an uri.
     * @param avatar the name of the avatar
     * @return the path as uri
     */
    public static Uri getAvatarUri(String avatar) {
        return Uri.parse("file:" + getAvatarPath(avatar));
    }

    /**
     * Avoid instantiation it's an helper class.
     */
    private AvatarUtil() {
        // Static helper class
    }
}