/*
 * Copyright (C) 2013 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.documentsui;

import static com.android.documentsui.model.DocumentInfo.getCursorString;

import android.content.ContentProvider;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.content.Context;
import android.content.Intent;
import android.content.UriMatcher;
import android.content.pm.ResolveInfo;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.net.Uri;
import android.os.Bundle;
import android.provider.DocumentsContract;
import android.provider.DocumentsContract.Document;
import android.provider.DocumentsContract.Root;
import android.text.format.DateUtils;
import android.util.Log;

import com.android.documentsui.model.DocumentStack;
import com.android.documentsui.model.DurableUtils;
import com.android.internal.util.Predicate;
import com.google.android.collect.Sets;

import libcore.io.IoUtils;

import java.io.IOException;
import java.util.Set;

public class RecentsProvider extends ContentProvider {
    private static final String TAG = "RecentsProvider";

    private static final long MAX_HISTORY_IN_MILLIS = 45 * DateUtils.DAY_IN_MILLIS;

    private static final String AUTHORITY = "com.android.documentsui.recents";

    private static final UriMatcher sMatcher = new UriMatcher(UriMatcher.NO_MATCH);

    private static final int URI_RECENT = 1;
    private static final int URI_STATE = 2;
    private static final int URI_RESUME = 3;

    public static final String METHOD_PURGE = "purge";
    public static final String METHOD_PURGE_PACKAGE = "purgePackage";

    static {
        sMatcher.addURI(AUTHORITY, "recent", URI_RECENT);
        // state/authority/rootId/docId
        sMatcher.addURI(AUTHORITY, "state/*/*/*", URI_STATE);
        // resume/packageName
        sMatcher.addURI(AUTHORITY, "resume/*", URI_RESUME);
    }

    public static final String TABLE_RECENT = "recent";
    public static final String TABLE_STATE = "state";
    public static final String TABLE_RESUME = "resume";

    public static class RecentColumns {
        public static final String KEY = "key";
        public static final String STACK = "stack";
        public static final String TIMESTAMP = "timestamp";
    }

    public static class StateColumns {
        public static final String AUTHORITY = "authority";
        public static final String ROOT_ID = Root.COLUMN_ROOT_ID;
        public static final String DOCUMENT_ID = Document.COLUMN_DOCUMENT_ID;
        public static final String MODE = "mode";
        public static final String SORT_ORDER = "sortOrder";
    }

    public static class ResumeColumns {
        public static final String PACKAGE_NAME = "package_name";
        public static final String STACK = "stack";
        public static final String TIMESTAMP = "timestamp";
        public static final String EXTERNAL = "external";
    }

    public static Uri buildRecent() {
        return new Uri.Builder().scheme(ContentResolver.SCHEME_CONTENT)
                .authority(AUTHORITY).appendPath("recent").build();
    }

    public static Uri buildState(String authority, String rootId, String documentId) {
        return new Uri.Builder().scheme(ContentResolver.SCHEME_CONTENT).authority(AUTHORITY)
                .appendPath("state").appendPath(authority).appendPath(rootId).appendPath(documentId)
                .build();
    }

    public static Uri buildResume(String packageName) {
        return new Uri.Builder().scheme(ContentResolver.SCHEME_CONTENT)
                .authority(AUTHORITY).appendPath("resume").appendPath(packageName).build();
    }

    private DatabaseHelper mHelper;

    private static class DatabaseHelper extends SQLiteOpenHelper {
        private static final String DB_NAME = "recents.db";

        private static final int VERSION_INIT = 1;
        private static final int VERSION_AS_BLOB = 3;
        private static final int VERSION_ADD_EXTERNAL = 4;
        private static final int VERSION_ADD_RECENT_KEY = 5;

        public DatabaseHelper(Context context) {
            super(context, DB_NAME, null, VERSION_ADD_RECENT_KEY);
        }

        @Override
        public void onCreate(SQLiteDatabase db) {

            db.execSQL("CREATE TABLE " + TABLE_RECENT + " (" +
                    RecentColumns.KEY + " TEXT PRIMARY KEY ON CONFLICT REPLACE," +
                    RecentColumns.STACK + " BLOB DEFAULT NULL," +
                    RecentColumns.TIMESTAMP + " INTEGER" +
                    ")");

            db.execSQL("CREATE TABLE " + TABLE_STATE + " (" +
                    StateColumns.AUTHORITY + " TEXT," +
                    StateColumns.ROOT_ID + " TEXT," +
                    StateColumns.DOCUMENT_ID + " TEXT," +
                    StateColumns.MODE + " INTEGER," +
                    StateColumns.SORT_ORDER + " INTEGER," +
                    "PRIMARY KEY (" + StateColumns.AUTHORITY + ", " + StateColumns.ROOT_ID + ", "
                    + StateColumns.DOCUMENT_ID + ")" +
                    ")");

            db.execSQL("CREATE TABLE " + TABLE_RESUME + " (" +
                    ResumeColumns.PACKAGE_NAME + " TEXT NOT NULL PRIMARY KEY," +
                    ResumeColumns.STACK + " BLOB DEFAULT NULL," +
                    ResumeColumns.TIMESTAMP + " INTEGER," +
                    ResumeColumns.EXTERNAL + " INTEGER NOT NULL DEFAULT 0" +
                    ")");
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            Log.w(TAG, "Upgrading database; wiping app data");
            db.execSQL("DROP TABLE IF EXISTS " + TABLE_RECENT);
            db.execSQL("DROP TABLE IF EXISTS " + TABLE_STATE);
            db.execSQL("DROP TABLE IF EXISTS " + TABLE_RESUME);
            onCreate(db);
        }
    }

    @Override
    public boolean onCreate() {
        mHelper = new DatabaseHelper(getContext());
        return true;
    }

    @Override
    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
            String sortOrder) {
        final SQLiteDatabase db = mHelper.getReadableDatabase();
        switch (sMatcher.match(uri)) {
            case URI_RECENT:
                final long cutoff = System.currentTimeMillis() - MAX_HISTORY_IN_MILLIS;
                return db.query(TABLE_RECENT, projection, RecentColumns.TIMESTAMP + ">" + cutoff,
                        null, null, null, sortOrder);
            case URI_STATE:
                final String authority = uri.getPathSegments().get(1);
                final String rootId = uri.getPathSegments().get(2);
                final String documentId = uri.getPathSegments().get(3);
                return db.query(TABLE_STATE, projection, StateColumns.AUTHORITY + "=? AND "
                        + StateColumns.ROOT_ID + "=? AND " + StateColumns.DOCUMENT_ID + "=?",
                        new String[] { authority, rootId, documentId }, null, null, sortOrder);
            case URI_RESUME:
                final String packageName = uri.getPathSegments().get(1);
                return db.query(TABLE_RESUME, projection, ResumeColumns.PACKAGE_NAME + "=?",
                        new String[] { packageName }, null, null, sortOrder);
            default:
                throw new UnsupportedOperationException("Unsupported Uri " + uri);
        }
    }

    @Override
    public String getType(Uri uri) {
        return null;
    }

    @Override
    public Uri insert(Uri uri, ContentValues values) {
        final SQLiteDatabase db = mHelper.getWritableDatabase();
        final ContentValues key = new ContentValues();
        switch (sMatcher.match(uri)) {
            case URI_RECENT:
                values.put(RecentColumns.TIMESTAMP, System.currentTimeMillis());
                db.insert(TABLE_RECENT, null, values);
                final long cutoff = System.currentTimeMillis() - MAX_HISTORY_IN_MILLIS;
                db.delete(TABLE_RECENT, RecentColumns.TIMESTAMP + "<" + cutoff, null);
                return uri;
            case URI_STATE:
                final String authority = uri.getPathSegments().get(1);
                final String rootId = uri.getPathSegments().get(2);
                final String documentId = uri.getPathSegments().get(3);

                key.put(StateColumns.AUTHORITY, authority);
                key.put(StateColumns.ROOT_ID, rootId);
                key.put(StateColumns.DOCUMENT_ID, documentId);

                // Ensure that row exists, then update with changed values
                db.insertWithOnConflict(TABLE_STATE, null, key, SQLiteDatabase.CONFLICT_IGNORE);
                db.update(TABLE_STATE, values, StateColumns.AUTHORITY + "=? AND "
                        + StateColumns.ROOT_ID + "=? AND " + StateColumns.DOCUMENT_ID + "=?",
                        new String[] { authority, rootId, documentId });

                return uri;
            case URI_RESUME:
                values.put(ResumeColumns.TIMESTAMP, System.currentTimeMillis());

                final String packageName = uri.getPathSegments().get(1);
                key.put(ResumeColumns.PACKAGE_NAME, packageName);

                // Ensure that row exists, then update with changed values
                db.insertWithOnConflict(TABLE_RESUME, null, key, SQLiteDatabase.CONFLICT_IGNORE);
                db.update(TABLE_RESUME, values, ResumeColumns.PACKAGE_NAME + "=?",
                        new String[] { packageName });
                return uri;
            default:
                throw new UnsupportedOperationException("Unsupported Uri " + uri);
        }
    }

    @Override
    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
        throw new UnsupportedOperationException("Unsupported Uri " + uri);
    }

    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        throw new UnsupportedOperationException("Unsupported Uri " + uri);
    }

    @Override
    public Bundle call(String method, String arg, Bundle extras) {
        if (METHOD_PURGE.equals(method)) {
            // Purge references to unknown authorities
            final Intent intent = new Intent(DocumentsContract.PROVIDER_INTERFACE);
            final Set<String> knownAuth = Sets.newHashSet();
            for (ResolveInfo info : getContext()
                    .getPackageManager().queryIntentContentProviders(intent, 0)) {
                knownAuth.add(info.providerInfo.authority);
            }

            purgeByAuthority(new Predicate<String>() {
                @Override
                public boolean apply(String authority) {
                    // Purge unknown authorities
                    return !knownAuth.contains(authority);
                }
            });

            return null;

        } else if (METHOD_PURGE_PACKAGE.equals(method)) {
            // Purge references to authorities in given package
            final Intent intent = new Intent(DocumentsContract.PROVIDER_INTERFACE);
            intent.setPackage(arg);
            final Set<String> packageAuth = Sets.newHashSet();
            for (ResolveInfo info : getContext()
                    .getPackageManager().queryIntentContentProviders(intent, 0)) {
                packageAuth.add(info.providerInfo.authority);
            }

            if (!packageAuth.isEmpty()) {
                purgeByAuthority(new Predicate<String>() {
                    @Override
                    public boolean apply(String authority) {
                        // Purge authority matches
                        return packageAuth.contains(authority);
                    }
                });
            }

            return null;

        } else {
            return super.call(method, arg, extras);
        }
    }

    /**
     * Purge all internal data whose authority matches the given
     * {@link Predicate}.
     */
    private void purgeByAuthority(Predicate<String> predicate) {
        final SQLiteDatabase db = mHelper.getWritableDatabase();
        final DocumentStack stack = new DocumentStack();

        Cursor cursor = db.query(TABLE_RECENT, null, null, null, null, null, null);
        try {
            while (cursor.moveToNext()) {
                try {
                    final byte[] rawStack = cursor.getBlob(
                            cursor.getColumnIndex(RecentColumns.STACK));
                    DurableUtils.readFromArray(rawStack, stack);

                    if (stack.root != null && predicate.apply(stack.root.authority)) {
                        final String key = getCursorString(cursor, RecentColumns.KEY);
                        db.delete(TABLE_RECENT, RecentColumns.KEY + "=?", new String[] { key });
                    }
                } catch (IOException ignored) {
                }
            }
        } finally {
            IoUtils.closeQuietly(cursor);
        }

        cursor = db.query(TABLE_STATE, new String[] {
                StateColumns.AUTHORITY }, null, null, StateColumns.AUTHORITY, null, null);
        try {
            while (cursor.moveToNext()) {
                final String authority = getCursorString(cursor, StateColumns.AUTHORITY);
                if (predicate.apply(authority)) {
                    db.delete(TABLE_STATE, StateColumns.AUTHORITY + "=?", new String[] {
                            authority });
                    Log.d(TAG, "Purged state for " + authority);
                }
            }
        } finally {
            IoUtils.closeQuietly(cursor);
        }

        cursor = db.query(TABLE_RESUME, null, null, null, null, null, null);
        try {
            while (cursor.moveToNext()) {
                try {
                    final byte[] rawStack = cursor.getBlob(
                            cursor.getColumnIndex(ResumeColumns.STACK));
                    DurableUtils.readFromArray(rawStack, stack);

                    if (stack.root != null && predicate.apply(stack.root.authority)) {
                        final String packageName = getCursorString(
                                cursor, ResumeColumns.PACKAGE_NAME);
                        db.delete(TABLE_RESUME, ResumeColumns.PACKAGE_NAME + "=?",
                                new String[] { packageName });
                    }
                } catch (IOException ignored) {
                }
            }
        } finally {
            IoUtils.closeQuietly(cursor);
        }
    }
}