/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.providers.downloads.ui;

import android.app.Activity;
import android.app.AlertDialog;
import android.app.DownloadManager;
import android.content.ActivityNotFoundException;
import android.content.ContentUris;
import android.content.Context;
import android.content.DialogInterface;
import android.content.DialogInterface.OnCancelListener;
import android.content.Intent;
import android.database.ContentObserver;
import android.database.Cursor;
import android.database.DataSetObserver;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.provider.Downloads;
import android.text.TextUtils;
import android.util.Log;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.view.animation.AnimationUtils;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.Button;
import android.widget.ExpandableListView;
import android.widget.ExpandableListView.OnChildClickListener;
import android.widget.ListView;
import android.widget.Toast;

import com.android.providers.downloads.ui.DownloadItem.DownloadSelectListener;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

/**
 *  View showing a list of all downloads the Download Manager knows about.
 */
public class DownloadList extends Activity
        implements OnChildClickListener, OnItemClickListener, DownloadSelectListener,
        OnClickListener, OnCancelListener {
    private static final String LOG_TAG = "DownloadList";

    private ExpandableListView mDateOrderedListView;
    private ListView mSizeOrderedListView;
    private View mEmptyView;
    private ViewGroup mSelectionMenuView;
    private Button mSelectionDeleteButton;
    private Button mSelectionRestartButton;

    private DownloadManager mDownloadManager;
    private Cursor mDateSortedCursor;
    private DateSortedDownloadAdapter mDateSortedAdapter;
    private Cursor mSizeSortedCursor;
    private DownloadAdapter mSizeSortedAdapter;
    private MyContentObserver mContentObserver = new MyContentObserver();
    private MyDataSetObserver mDataSetObserver = new MyDataSetObserver();

    private int mStatusColumnId;
    private int mIdColumnId;
    private int mLocalUriColumnId;
    private int mMediaTypeColumnId;
    private int mReasonColumndId;
    private int mMediaProviderUriId;

    private boolean mIsSortedBySize = false;
    private Set<Long> mSelectedIds = new HashSet<Long>();

    /**
     * We keep track of when a dialog is being displayed for a pending download, because if that
     * download starts running, we want to immediately hide the dialog.
     */
    private Long mQueuedDownloadId = null;
    private AlertDialog mQueuedDialog;


    private class MyContentObserver extends ContentObserver {
        public MyContentObserver() {
            super(new Handler());
        }

        @Override
        public void onChange(boolean selfChange) {
            handleDownloadsChanged();
        }
    }

    private class MyDataSetObserver extends DataSetObserver {
        @Override
        public void onChanged() {
            // may need to switch to or from the empty view
            chooseListToShow();
            ensureSomeGroupIsExpanded();
        }
    }

    @Override
    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);
        setupViews();

        mDownloadManager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);
        mDownloadManager.setAccessAllDownloads(true);
        DownloadManager.Query baseQuery = new DownloadManager.Query()
                .setOnlyIncludeVisibleInDownloadsUi(true);
        mDateSortedCursor = mDownloadManager.query(baseQuery);
        mSizeSortedCursor = mDownloadManager.query(baseQuery
                                                  .orderBy(DownloadManager.COLUMN_TOTAL_SIZE_BYTES,
                                                          DownloadManager.Query.ORDER_DESCENDING));

        // only attach everything to the listbox if we can access the download database. Otherwise,
        // just show it empty
        if (haveCursors()) {
            startManagingCursor(mDateSortedCursor);
            startManagingCursor(mSizeSortedCursor);

            mStatusColumnId =
                    mDateSortedCursor.getColumnIndexOrThrow(DownloadManager.COLUMN_STATUS);
            mIdColumnId =
                    mDateSortedCursor.getColumnIndexOrThrow(DownloadManager.COLUMN_ID);
            mLocalUriColumnId =
                    mDateSortedCursor.getColumnIndexOrThrow(DownloadManager.COLUMN_LOCAL_URI);
            mMediaTypeColumnId =
                    mDateSortedCursor.getColumnIndexOrThrow(DownloadManager.COLUMN_MEDIA_TYPE);
            mReasonColumndId =
                    mDateSortedCursor.getColumnIndexOrThrow(DownloadManager.COLUMN_REASON);
            mMediaProviderUriId =
                    mDateSortedCursor.getColumnIndexOrThrow(
                            DownloadManager.COLUMN_MEDIAPROVIDER_URI);

            mDateSortedAdapter = new DateSortedDownloadAdapter(this, mDateSortedCursor, this);
            mDateOrderedListView.setAdapter(mDateSortedAdapter);
            mSizeSortedAdapter = new DownloadAdapter(this, mSizeSortedCursor, this);
            mSizeOrderedListView.setAdapter(mSizeSortedAdapter);

            ensureSomeGroupIsExpanded();
        }

        chooseListToShow();
    }

    /**
     * If no group is expanded in the date-sorted list, expand the first one.
     */
    private void ensureSomeGroupIsExpanded() {
        mDateOrderedListView.post(new Runnable() {
            public void run() {
                if (mDateSortedAdapter.getGroupCount() == 0) {
                    return;
                }
                for (int group = 0; group < mDateSortedAdapter.getGroupCount(); group++) {
                    if (mDateOrderedListView.isGroupExpanded(group)) {
                        return;
                    }
                }
                mDateOrderedListView.expandGroup(0);
            }
        });
    }

    private void setupViews() {
        setContentView(R.layout.download_list);
        setTitle(getText(R.string.download_title));

        mDateOrderedListView = (ExpandableListView) findViewById(R.id.date_ordered_list);
        mDateOrderedListView.setOnChildClickListener(this);
        mSizeOrderedListView = (ListView) findViewById(R.id.size_ordered_list);
        mSizeOrderedListView.setOnItemClickListener(this);
        mEmptyView = findViewById(R.id.empty);

        mSelectionMenuView = (ViewGroup) findViewById(R.id.selection_menu);
        mSelectionDeleteButton = (Button) findViewById(R.id.selection_delete);
        mSelectionDeleteButton.setOnClickListener(this);
        mSelectionRestartButton = (Button) findViewById(R.id.selection_retry);
        mSelectionRestartButton.setOnClickListener(this);

        ((Button) findViewById(R.id.deselect_all)).setOnClickListener(this);
    }

    private boolean haveCursors() {
        return mDateSortedCursor != null && mSizeSortedCursor != null;
    }

    @Override
    protected void onResume() {
        super.onResume();
        if (haveCursors()) {
            mDateSortedCursor.registerContentObserver(mContentObserver);
            mDateSortedCursor.registerDataSetObserver(mDataSetObserver);
            refresh();
        }
    }

    @Override
    protected void onPause() {
        super.onPause();
        if (haveCursors()) {
            mDateSortedCursor.unregisterContentObserver(mContentObserver);
            mDateSortedCursor.unregisterDataSetObserver(mDataSetObserver);
        }
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putBoolean("isSortedBySize", mIsSortedBySize);
        outState.putLongArray("selection", getSelectionAsArray());
    }

    private long[] getSelectionAsArray() {
        long[] selectedIds = new long[mSelectedIds.size()];
        Iterator<Long> iterator = mSelectedIds.iterator();
        for (int i = 0; i < selectedIds.length; i++) {
            selectedIds[i] = iterator.next();
        }
        return selectedIds;
    }

    @Override
    protected void onRestoreInstanceState(Bundle savedInstanceState) {
        super.onRestoreInstanceState(savedInstanceState);
        mIsSortedBySize = savedInstanceState.getBoolean("isSortedBySize");
        mSelectedIds.clear();
        for (long selectedId : savedInstanceState.getLongArray("selection")) {
            mSelectedIds.add(selectedId);
        }
        chooseListToShow();
        showOrHideSelectionMenu();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        if (haveCursors()) {
            MenuInflater inflater = getMenuInflater();
            inflater.inflate(R.menu.download_menu, menu);
        }
        return true;
    }

    @Override
    public boolean onPrepareOptionsMenu(Menu menu) {
        menu.findItem(R.id.download_menu_sort_by_size).setVisible(!mIsSortedBySize);
        menu.findItem(R.id.download_menu_sort_by_date).setVisible(mIsSortedBySize);
        return super.onPrepareOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.download_menu_sort_by_size:
                mIsSortedBySize = true;
                chooseListToShow();
                return true;
            case R.id.download_menu_sort_by_date:
                mIsSortedBySize = false;
                chooseListToShow();
                return true;
        }
        return false;
    }

    /**
     * Show the correct ListView and hide the other, or hide both and show the empty view.
     */
    private void chooseListToShow() {
        mDateOrderedListView.setVisibility(View.GONE);
        mSizeOrderedListView.setVisibility(View.GONE);

        if (mDateSortedCursor == null || mDateSortedCursor.getCount() == 0) {
            mEmptyView.setVisibility(View.VISIBLE);
        } else {
            mEmptyView.setVisibility(View.GONE);
            activeListView().setVisibility(View.VISIBLE);
            activeListView().invalidateViews(); // ensure checkboxes get updated
        }
    }

    /**
     * @return the ListView that should currently be visible.
     */
    private ListView activeListView() {
        if (mIsSortedBySize) {
            return mSizeOrderedListView;
        }
        return mDateOrderedListView;
    }

    /**
     * @return an OnClickListener to delete the given downloadId from the Download Manager
     */
    private DialogInterface.OnClickListener getDeleteClickHandler(final long downloadId) {
        return new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                deleteDownload(downloadId);
            }
        };
    }

    /**
     * @return an OnClickListener to restart the given downloadId in the Download Manager
     */
    private DialogInterface.OnClickListener getRestartClickHandler(final long downloadId) {
        return new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                mDownloadManager.restartDownload(downloadId);
            }
        };
    }

    /**
     * Send an Intent to open the download currently pointed to by the given cursor.
     */
    private void openCurrentDownload(Cursor cursor) {
        Uri localUri = Uri.parse(cursor.getString(mLocalUriColumnId));
        try {
            getContentResolver().openFileDescriptor(localUri, "r").close();
        } catch (FileNotFoundException exc) {
            Log.d(LOG_TAG, "Failed to open download " + cursor.getLong(mIdColumnId), exc);
            showFailedDialog(cursor.getLong(mIdColumnId),
                    getString(R.string.dialog_file_missing_body));
            return;
        } catch (IOException exc) {
            // close() failed, not a problem
        }

        Intent intent = new Intent(Intent.ACTION_VIEW);
        intent.setDataAndType(localUri, cursor.getString(mMediaTypeColumnId));
        intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_GRANT_READ_URI_PERMISSION);
        try {
            startActivity(intent);
        } catch (ActivityNotFoundException ex) {
            Toast.makeText(this, R.string.download_no_application_title, Toast.LENGTH_LONG).show();
        }
    }

    private void handleItemClick(Cursor cursor) {
        long id = cursor.getInt(mIdColumnId);
        switch (cursor.getInt(mStatusColumnId)) {
            case DownloadManager.STATUS_PENDING:
            case DownloadManager.STATUS_RUNNING:
                sendRunningDownloadClickedBroadcast(id);
                break;

            case DownloadManager.STATUS_PAUSED:
                if (isPausedForWifi(cursor)) {
                    mQueuedDownloadId = id;
                    mQueuedDialog = new AlertDialog.Builder(this)
                            .setTitle(R.string.dialog_title_not_available)
                            .setMessage(R.string.dialog_queued_body)
                            .setPositiveButton(R.string.keep_queued_download, null)
                            .setNegativeButton(R.string.remove_download, getDeleteClickHandler(id))
                            .setOnCancelListener(this)
                            .show();
                } else {
                    sendRunningDownloadClickedBroadcast(id);
                }
                break;

            case DownloadManager.STATUS_SUCCESSFUL:
                openCurrentDownload(cursor);
                break;

            case DownloadManager.STATUS_FAILED:
                showFailedDialog(id, getErrorMessage(cursor));
                break;
        }
    }

    /**
     * @return the appropriate error message for the failed download pointed to by cursor
     */
    private String getErrorMessage(Cursor cursor) {
        switch (cursor.getInt(mReasonColumndId)) {
            case DownloadManager.ERROR_FILE_ALREADY_EXISTS:
                if (isOnExternalStorage(cursor)) {
                    return getString(R.string.dialog_file_already_exists);
                } else {
                    // the download manager should always find a free filename for cache downloads,
                    // so this indicates a strange internal error
                    return getUnknownErrorMessage();
                }

            case DownloadManager.ERROR_INSUFFICIENT_SPACE:
                if (isOnExternalStorage(cursor)) {
                    return getString(R.string.dialog_insufficient_space_on_external);
                } else {
                    return getString(R.string.dialog_insufficient_space_on_cache);
                }

            case DownloadManager.ERROR_DEVICE_NOT_FOUND:
                return getString(R.string.dialog_media_not_found);

            case DownloadManager.ERROR_CANNOT_RESUME:
                return getString(R.string.dialog_cannot_resume);

            default:
                return getUnknownErrorMessage();
        }
    }

    private boolean isOnExternalStorage(Cursor cursor) {
        String localUriString = cursor.getString(mLocalUriColumnId);
        if (localUriString == null) {
            return false;
        }
        Uri localUri = Uri.parse(localUriString);
        if (!localUri.getScheme().equals("file")) {
            return false;
        }
        String path = localUri.getPath();
        String externalRoot = Environment.getExternalStorageDirectory().getPath();
        return path.startsWith(externalRoot);
    }

    private String getUnknownErrorMessage() {
        return getString(R.string.dialog_failed_body);
    }

    private void showFailedDialog(long downloadId, String dialogBody) {
        new AlertDialog.Builder(this)
                .setTitle(R.string.dialog_title_not_available)
                .setMessage(dialogBody)
                .setPositiveButton(R.string.remove_download, getDeleteClickHandler(downloadId))
                .setNegativeButton(R.string.retry_download, getRestartClickHandler(downloadId))
                .show();
    }

    /**
     * TODO use constants/shared code?
     */
    private void sendRunningDownloadClickedBroadcast(long id) {
        Intent intent = new Intent("android.intent.action.DOWNLOAD_LIST");
        intent.setClassName("com.android.providers.downloads",
                "com.android.providers.downloads.DownloadReceiver");
        intent.setData(ContentUris.withAppendedId(Downloads.Impl.ALL_DOWNLOADS_CONTENT_URI, id));
        intent.putExtra("multiple", false);
        sendBroadcast(intent);
    }

    // handle a click from the date-sorted list
    @Override
    public boolean onChildClick(ExpandableListView parent, View v,
            int groupPosition, int childPosition, long id) {
        mDateSortedAdapter.moveCursorToChildPosition(groupPosition, childPosition);
        handleItemClick(mDateSortedCursor);
        return true;
    }

    // handle a click from the size-sorted list
    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
        mSizeSortedCursor.moveToPosition(position);
        handleItemClick(mSizeSortedCursor);
    }

    // handle a click on one of the download item checkboxes
    @Override
    public void onDownloadSelectionChanged(long downloadId, boolean isSelected) {
        if (isSelected) {
            mSelectedIds.add(downloadId);
        } else {
            mSelectedIds.remove(downloadId);
        }
        showOrHideSelectionMenu();
    }

    private void showOrHideSelectionMenu() {
        boolean shouldBeVisible = !mSelectedIds.isEmpty();
        boolean isVisible = mSelectionMenuView.getVisibility() == View.VISIBLE;
        if (shouldBeVisible) {
            updateSelectionMenu();
            if (!isVisible) {
                // show menu
                mSelectionMenuView.setVisibility(View.VISIBLE);
                mSelectionMenuView.startAnimation(
                        AnimationUtils.loadAnimation(this, R.anim.footer_appear));
            }
        } else if (!shouldBeVisible && isVisible) {
            // hide menu
            mSelectionMenuView.setVisibility(View.GONE);
            mSelectionMenuView.startAnimation(
                    AnimationUtils.loadAnimation(this, R.anim.footer_disappear));
        }
    }

    /**
     * Set up the contents of the selection menu based on the current selection.
     */
    private void updateSelectionMenu() {
        mSelectionRestartButton.setVisibility(View.GONE);
        int deleteButtonStringId = R.string.delete_download;
        if (mSelectedIds.size() == 1) {
            Cursor cursor = mDownloadManager.query(new DownloadManager.Query()
                    .setFilterById(mSelectedIds.iterator().next()));
            try {
                cursor.moveToFirst();
                switch (cursor.getInt(mStatusColumnId)) {
                    case DownloadManager.STATUS_FAILED:
                        deleteButtonStringId = R.string.remove_download;
                        mSelectionRestartButton.setVisibility(View.VISIBLE);
                        break;

                    case DownloadManager.STATUS_PENDING:
                        deleteButtonStringId = R.string.remove_download;
                        break;

                    case DownloadManager.STATUS_PAUSED:
                    case DownloadManager.STATUS_RUNNING:
                        deleteButtonStringId = R.string.cancel_running_download;
                        break;
                }
            } finally {
                cursor.close();
            }
        }
        mSelectionDeleteButton.setText(deleteButtonStringId);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.selection_delete:
                for (Long downloadId : mSelectedIds) {
                    deleteDownload(downloadId);
                }
                clearSelection();
                break;

            case R.id.selection_retry:
                for (Long downloadId : mSelectedIds) {
                    mDownloadManager.restartDownload(downloadId);
                }
                clearSelection();
                break;

            case R.id.deselect_all:
                clearSelection();
                break;
        }
    }

    /**
     * Requery the database and update the UI.
     */
    private void refresh() {
        mDateSortedCursor.requery();
        mSizeSortedCursor.requery();
        // Adapters get notification of changes and update automatically
    }

    private void clearSelection() {
        mSelectedIds.clear();
        showOrHideSelectionMenu();
    }

    /**
     * Delete a download from the Download Manager.
     */
    private void deleteDownload(long downloadId) {
        if (moveToDownload(downloadId)) {
            int status = mDateSortedCursor.getInt(mStatusColumnId);
            boolean isComplete = status == DownloadManager.STATUS_SUCCESSFUL
                    || status == DownloadManager.STATUS_FAILED;
            String localUri = mDateSortedCursor.getString(mLocalUriColumnId);
            if (isComplete && localUri != null) {
                String path = Uri.parse(localUri).getPath();
                if (path.startsWith(Environment.getExternalStorageDirectory().getPath())) {
                    String mediaProviderUri = mDateSortedCursor.getString(mMediaProviderUriId);
                    if (TextUtils.isEmpty(mediaProviderUri)) {
                        // downloads database doesn't have the mediaprovider_uri. It means
                        // this download occurred before mediaprovider_uri column existed
                        // in downloads table. Since MediaProvider needs the mediaprovider_uri to
                        // delete this download, just set the 'deleted' flag to 1 on this row
                        // in the database. DownloadService, upon seeing this flag set to 1, will
                        // re-scan the file and get the MediaProviderUri and then delete the file
                        mDownloadManager.markRowDeleted(downloadId);
                        return;
                    } else {
                        getContentResolver().delete(Uri.parse(mediaProviderUri), null, null);
                    }
                }
            }
        }
        mDownloadManager.remove(downloadId);
    }

    @Override
    public boolean isDownloadSelected(long id) {
        return mSelectedIds.contains(id);
    }

    /**
     * Called when there's a change to the downloads database.
     */
    void handleDownloadsChanged() {
        checkSelectionForDeletedEntries();

        if (mQueuedDownloadId != null && moveToDownload(mQueuedDownloadId)) {
            if (mDateSortedCursor.getInt(mStatusColumnId) != DownloadManager.STATUS_PAUSED
                    || !isPausedForWifi(mDateSortedCursor)) {
                mQueuedDialog.cancel();
            }
        }
    }

    private boolean isPausedForWifi(Cursor cursor) {
        return cursor.getInt(mReasonColumndId) == DownloadManager.PAUSED_QUEUED_FOR_WIFI;
    }

    /**
     * Check if any of the selected downloads have been deleted from the downloads database, and
     * remove such downloads from the selection.
     */
    private void checkSelectionForDeletedEntries() {
        // gather all existing IDs...
        Set<Long> allIds = new HashSet<Long>();
        for (mDateSortedCursor.moveToFirst(); !mDateSortedCursor.isAfterLast();
                mDateSortedCursor.moveToNext()) {
            allIds.add(mDateSortedCursor.getLong(mIdColumnId));
        }

        // ...and check if any selected IDs are now missing
        for (Iterator<Long> iterator = mSelectedIds.iterator(); iterator.hasNext(); ) {
            if (!allIds.contains(iterator.next())) {
                iterator.remove();
            }
        }
    }

    /**
     * Move {@link #mDateSortedCursor} to the download with the given ID.
     * @return true if the specified download ID was found; false otherwise
     */
    private boolean moveToDownload(long downloadId) {
        for (mDateSortedCursor.moveToFirst(); !mDateSortedCursor.isAfterLast();
                mDateSortedCursor.moveToNext()) {
            if (mDateSortedCursor.getLong(mIdColumnId) == downloadId) {
                return true;
            }
        }
        return false;
    }

    /**
     * Called when a dialog for a pending download is canceled.
     */
    @Override
    public void onCancel(DialogInterface dialog) {
        mQueuedDownloadId = null;
        mQueuedDialog = null;
    }
}