// (C) Copyright 2015 Moodle Pty Ltd.
//
// 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.

import { Injectable } from '@angular/core';
import { FileEntry } from '@ionic-native/file';

import { CoreApp } from '@services/app';
import { CoreFile } from '@services/file';
import { CoreFilepool } from '@services/filepool';
import { CoreSites } from '@services/sites';
import { CoreWS, CoreWSExternalFile } from '@services/ws';
import { CoreDomUtils } from '@services/utils/dom';
import { CoreUrlUtils } from '@services/utils/url';
import { CoreUtils } from '@services/utils/utils';
import { CoreConstants } from '@core/constants';
import { CoreError } from '@classes/errors/error';
import { makeSingleton, Translate } from '@singletons/core.singletons';

/**
 * Provider to provide some helper functions regarding files and packages.
 */
@Injectable()
export class CoreFileHelperProvider {

    /**
     * Convenience function to open a file, downloading it if needed.
     *
     * @param file The file to download.
     * @param component The component to link the file to.
     * @param componentId An ID to use in conjunction with the component.
     * @param state The file's state. If not provided, it will be calculated.
     * @param onProgress Function to call on progress.
     * @param siteId The site ID. If not defined, current site.
     * @return Resolved on success.
     */
    async downloadAndOpenFile(
        file: CoreWSExternalFile,
        component: string,
        componentId: string | number,
        state?: string,
        onProgress?: CoreFileHelperOnProgress,
        siteId?: string,
    ): Promise<void> {
        siteId = siteId || CoreSites.instance.getCurrentSiteId();

        const fileUrl = file.fileurl;
        const timemodified = this.getFileTimemodified(file);

        if (!this.isOpenableInApp(file)) {
            await this.showConfirmOpenUnsupportedFile();
        }

        let url = await this.downloadFileIfNeeded(file, fileUrl, component, componentId, timemodified, state, onProgress, siteId);

        if (!url) {
            return;
        }

        if (!CoreUrlUtils.instance.isLocalFileUrl(url)) {
            /* In iOS, if we use the same URL in embedded browser and background download then the download only
               downloads a few bytes (cached ones). Add a hash to the URL so both URLs are different. */
            url = url + '#moodlemobile-embedded';

            try {
                await CoreUtils.instance.openOnlineFile(url);

                return;
            } catch (error) {
                // Error opening the file, some apps don't allow opening online files.
                if (!CoreFile.instance.isAvailable()) {
                    throw error;
                }

                // Get the state.
                if (!state) {
                    state = await CoreFilepool.instance.getFileStateByUrl(siteId, fileUrl, timemodified);
                }

                if (state == CoreConstants.DOWNLOADING) {
                    throw new CoreError(Translate.instance.instant('core.erroropenfiledownloading'));
                }

                if (state === CoreConstants.NOT_DOWNLOADED) {
                    // File is not downloaded, download and then return the local URL.
                    url = await this.downloadFile(fileUrl, component, componentId, timemodified, onProgress, file, siteId);
                } else {
                    // File is outdated and can't be opened in online, return the local URL.
                    url = await CoreFilepool.instance.getInternalUrlByUrl(siteId, fileUrl);
                }
            }
        }

        return CoreUtils.instance.openFile(url);
    }

    /**
     * Download a file if it needs to be downloaded.
     *
     * @param file The file to download.
     * @param fileUrl The file URL.
     * @param component The component to link the file to.
     * @param componentId An ID to use in conjunction with the component.
     * @param timemodified The time this file was modified.
     * @param state The file's state. If not provided, it will be calculated.
     * @param onProgress Function to call on progress.
     * @param siteId The site ID. If not defined, current site.
     * @return Resolved with the URL to use on success.
     */
    protected async downloadFileIfNeeded(
        file: CoreWSExternalFile,
        fileUrl: string,
        component?: string,
        componentId?: string | number,
        timemodified?: number,
        state?: string,
        onProgress?: CoreFileHelperOnProgress,
        siteId?: string,
    ): Promise<string> {
        siteId = siteId || CoreSites.instance.getCurrentSiteId();

        const site = await CoreSites.instance.getSite(siteId);
        const fixedUrl = await site.checkAndFixPluginfileURL(fileUrl);

        if (!CoreFile.instance.isAvailable()) {
            // Use the online URL.
            return fixedUrl;
        }

        if (!state) {
            // Calculate the state.
            state = await CoreFilepool.instance.getFileStateByUrl(siteId, fileUrl, timemodified);
        }

        // The file system is available.
        const isWifi = CoreApp.instance.isWifi();
        const isOnline = CoreApp.instance.isOnline();

        if (state == CoreConstants.DOWNLOADED) {
            // File is downloaded, get the local file URL.
            return CoreFilepool.instance.getUrlByUrl(siteId, fileUrl, component, componentId, timemodified, false, false, file);
        } else {
            if (!isOnline && !this.isStateDownloaded(state)) {
                // Not downloaded and user is offline, reject.
                throw new CoreError(Translate.instance.instant('core.networkerrormsg'));
            }

            if (onProgress) {
                // This call can take a while. Send a fake event to notify that we're doing some calculations.
                onProgress({ calculating: true });
            }

            try {
                await CoreFilepool.instance.shouldDownloadBeforeOpen(fixedUrl, file.filesize || 0);
            } catch (error) {
                // Start the download if in wifi, but return the URL right away so the file is opened.
                if (isWifi) {
                    this.downloadFile(fileUrl, component, componentId, timemodified, onProgress, file, siteId);
                }

                if (!this.isStateDownloaded(state) || isOnline) {
                    // Not downloaded or online, return the online URL.
                    return fixedUrl;
                } else {
                    // Outdated but offline, so we return the local URL.
                    return CoreFilepool.instance.getUrlByUrl(
                        siteId, fileUrl, component, componentId, timemodified, false, false, file);
                }
            }

            // Download the file first.
            if (state == CoreConstants.DOWNLOADING) {
                // It's already downloading, stop.
                return fixedUrl;
            }

            // Download and then return the local URL.
            return this.downloadFile(fileUrl, component, componentId, timemodified, onProgress, file, siteId);
        }
    }

    /**
     * Download the file.
     *
     * @param fileUrl The file URL.
     * @param component The component to link the file to.
     * @param componentId An ID to use in conjunction with the component.
     * @param timemodified The time this file was modified.
     * @param onProgress Function to call on progress.
     * @param file The file to download.
     * @param siteId The site ID. If not defined, current site.
     * @return Resolved with internal URL on success, rejected otherwise.
     */
    async downloadFile(
        fileUrl: string,
        component?: string,
        componentId?: string | number,
        timemodified?: number,
        onProgress?: (event: ProgressEvent) => void,
        file?: CoreWSExternalFile,
        siteId?: string,
    ): Promise<string> {
        siteId = siteId || CoreSites.instance.getCurrentSiteId();

        // Get the site and check if it can download files.
        const site = await CoreSites.instance.getSite(siteId);

        if (!site.canDownloadFiles()) {
            throw new CoreError(Translate.instance.instant('core.cannotdownloadfiles'));
        }

        try {
            return await CoreFilepool.instance.downloadUrl(siteId, fileUrl, false, component, componentId, timemodified,
                onProgress, undefined, file);
        } catch (error) {
            // Download failed, check the state again to see if the file was downloaded before.
            const state = await CoreFilepool.instance.getFileStateByUrl(siteId, fileUrl, timemodified);

            if (this.isStateDownloaded(state)) {
                return CoreFilepool.instance.getInternalUrlByUrl(siteId, fileUrl);
            } else {
                throw error;
            }
        }
    }

    /**
     * Get the file's URL.
     *
     * @param file The file.
     * @deprecated since 3.9.5. Get directly the fileurl instead.
     */
    getFileUrl(file: CoreWSExternalFile): string | undefined {
        return file.fileurl;
    }

    /**
     * Get the file's timemodified.
     *
     * @param file The file.
     */
    getFileTimemodified(file: CoreWSExternalFile): number {
        return file.timemodified || 0;
    }

    /**
     * Check if a state is downloaded or outdated.
     *
     * @param state The state to check.
     */
    isStateDownloaded(state: string): boolean {
        return state === CoreConstants.DOWNLOADED || state === CoreConstants.OUTDATED;
    }

    /**
     * Whether the file has to be opened in browser (external repository).
     * The file must have a mimetype attribute.
     *
     * @param file The file to check.
     * @return Whether the file should be opened in browser.
     */
    shouldOpenInBrowser(file: CoreWSExternalFile): boolean {
        if (!file || !file.isexternalfile || !file.mimetype) {
            return false;
        }

        const mimetype = file.mimetype;
        if (mimetype.indexOf('application/vnd.google-apps.') != -1) {
            // Google Docs file, always open in browser.
            return true;
        }

        if (file.repositorytype == 'onedrive') {
            // In OneDrive, open in browser the office docs
            return mimetype.indexOf('application/vnd.openxmlformats-officedocument') != -1 ||
                    mimetype == 'text/plain' || mimetype == 'document/unknown';
        }

        return false;
    }

    /**
     * Calculate the total size of the given files.
     *
     * @param files The files to check.
     * @return Total files size.
     */
    async getTotalFilesSize(files: (CoreWSExternalFile | FileEntry)[]): Promise<number> {
        let totalSize = 0;

        for (const file of files) {
            totalSize += await this.getFileSize(file);
        }

        return totalSize;
    }

    /**
     * Calculate the file size.
     *
     * @param file The file to check.
     * @return File size.
     */
    async getFileSize(file: CoreWSExternalFile | FileEntry): Promise<number> {
        if ('filesize' in file && (file.filesize || file.filesize === 0)) {
            return file.filesize;
        }

        // If it's a remote file. First check if we have the file downloaded since it's more reliable.
        if ('filename' in file) {
            const fileUrl = file.fileurl;

            try {
                const siteId = CoreSites.instance.getCurrentSiteId();

                const path = await CoreFilepool.instance.getFilePathByUrl(siteId, fileUrl);
                const fileEntry = await CoreFile.instance.getFile(path);
                const fileObject = await CoreFile.instance.getFileObjectFromFileEntry(fileEntry);

                return fileObject.size;
            } catch (error) {
                // Error getting the file, maybe it's not downloaded. Get remote size.
                const size = await CoreWS.instance.getRemoteFileSize(fileUrl);

                if (size === -1) {
                    throw new CoreError(`Couldn't determine file size: ${fileUrl}`);
                }

                return size;
            }
        }

        // If it's a local file, get its size.
        if ('name' in file) {
            const fileObject = await CoreFile.instance.getFileObjectFromFileEntry(file);

            return fileObject.size;
        }

        throw new CoreError('Couldn\'t determine file size');
    }

    /**
     * Is the file openable in app.
     *
     * @param file The file to check.
     * @return bool.
     */
    isOpenableInApp(file: {filename?: string; name?: string}): boolean {
        const regex = /(?:\.([^.]+))?$/;
        const regexResult = regex.exec(file.filename || file.name || '');

        if (!regexResult || !regexResult[1]) {
            // Couldn't find the extension. Assume it's openable.
            return true;
        }

        return !this.isFileTypeExcludedInApp(regexResult[1]);
    }

    /**
     * Show a confirm asking the user if we wants to open the file.
     *
     * @param onlyDownload Whether the user is only downloading the file, not opening it.
     * @return Promise resolved if confirmed, rejected otherwise.
     */
    showConfirmOpenUnsupportedFile(onlyDownload?: boolean): Promise<void> {
        const message = Translate.instance.instant('core.cannotopeninapp' + (onlyDownload ? 'download' : ''));
        const okButton = Translate.instance.instant(onlyDownload ? 'core.downloadfile' : 'core.openfile');

        return CoreDomUtils.instance.showConfirm(message, undefined, okButton, undefined, { cssClass: 'core-modal-force-on-top' });
    }

    /**
     * Is the file type excluded to open in app.
     *
     * @param file The file to check.
     * @return bool.
     */
    isFileTypeExcludedInApp(fileType: string): boolean {
        const currentSite = CoreSites.instance.getCurrentSite();
        const fileTypeExcludeList = currentSite?.getStoredConfig('tool_mobile_filetypeexclusionlist');

        if (!fileTypeExcludeList) {
            return false;
        }

        const regEx = new RegExp('(,|^)' + fileType + '(,|$)', 'g');

        return !!fileTypeExcludeList.match(regEx);
    }

}

export class CoreFileHelper extends makeSingleton(CoreFileHelperProvider) {}

export type CoreFileHelperOnProgress = (event?: ProgressEvent | { calculating: true }) => void;