/*
 * Copyright 2010-2019 Gildas Lormeau
 * contact : gildas.lormeau <at> gmail.com
 * 
 * This file is part of SingleFile.
 *
 *   The code in this file is free software: you can redistribute it and/or 
 *   modify it under the terms of the GNU Affero General Public License 
 *   (GNU AGPL) as published by the Free Software Foundation, either version 3
 *   of the License, or (at your option) any later version.
 * 
 *   The code in this file is distributed in the hope that it will be useful, 
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of 
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero 
 *   General Public License for more details.
 *
 *   As additional permission under GNU AGPL version 3 section 7, you may 
 *   distribute UNMODIFIED VERSIONS OF THIS file without the copy of the GNU 
 *   AGPL normally required by section 4, provided you include this license 
 *   notice and a URL through which recipients can access the Corresponding 
 *   Source.
 */

/* global browser, singlefile, Blob, URL, document */

singlefile.extension.core.bg.downloads = (() => {

	const partialContents = new Map();
	const MIMETYPE_HTML = "text/html";
	const STATE_DOWNLOAD_COMPLETE = "complete";
	const STATE_DOWNLOAD_INTERRUPTED = "interrupted";
	const STATE_ERROR_CANCELED_CHROMIUM = "USER_CANCELED";
	const ERROR_DOWNLOAD_CANCELED_GECKO = "canceled";
	const ERROR_CONFLICT_ACTION_GECKO = "conflictaction prompt not yet implemented";
	const ERROR_INCOGNITO_GECKO = "'incognito'";
	const ERROR_INCOGNITO_GECKO_ALT = "\"incognito\"";
	const ERROR_INVALID_FILENAME_GECKO = "illegal characters";
	const ERROR_INVALID_FILENAME_CHROMIUM = "invalid filename";

	return {
		onMessage,
		download,
		downloadPage
	};

	async function onMessage(message, sender) {
		if (message.method.endsWith(".download")) {
			let contents;
			if (message.truncated) {
				contents = partialContents.get(sender.tab.id);
				if (!contents) {
					contents = [];
					partialContents.set(sender.tab.id, contents);
				}
				contents.push(message.content);
				if (message.finished) {
					partialContents.delete(sender.tab.id);
				}
			} else if (message.content) {
				contents = [message.content];
			}
			if (!message.truncated || message.finished) {
				if (message.saveToClipboard) {
					message.content = contents.join("");
					saveToClipboard(message);
				} else {
					message.url = URL.createObjectURL(new Blob([contents], { type: MIMETYPE_HTML }));
					try {
						await downloadPage(message, {
							confirmFilename: message.confirmFilename,
							incognito: sender.tab.incognito,
							filenameConflictAction: message.filenameConflictAction,
							filenameReplacementCharacter: message.filenameReplacementCharacter
						});
					} catch (error) {
						console.error(error); // eslint-disable-line no-console
						singlefile.extension.ui.bg.main.onError(sender.tab.id);
					} finally {
						URL.revokeObjectURL(message.url);
					}
				}
			}
			return {};
		}
	}

	async function downloadPage(page, options) {
		const downloadInfo = {
			url: page.url,
			saveAs: options.confirmFilename,
			filename: page.filename,
			conflictAction: options.filenameConflictAction
		};
		if (options.incognito) {
			downloadInfo.incognito = true;
		}
		await download(downloadInfo, options.filenameReplacementCharacter);
	}

	async function download(downloadInfo, replacementCharacter) {
		let downloadId;
		try {
			downloadId = await browser.downloads.download(downloadInfo);
		} catch (error) {
			if (error.message) {
				const errorMessage = error.message.toLowerCase();
				const invalidFilename = errorMessage.includes(ERROR_INVALID_FILENAME_GECKO) || errorMessage.includes(ERROR_INVALID_FILENAME_CHROMIUM);
				if (invalidFilename && downloadInfo.filename.startsWith(".")) {
					downloadInfo.filename = replacementCharacter + downloadInfo.filename;
					return download(downloadInfo, replacementCharacter);
				} else if (invalidFilename && downloadInfo.filename.includes(",")) {
					downloadInfo.filename = downloadInfo.filename.replace(/,/g, replacementCharacter);
					return download(downloadInfo, replacementCharacter);
				} else if (invalidFilename && !downloadInfo.filename.match(/^[\x00-\x7F]+$/)) { // eslint-disable-line  no-control-regex
					downloadInfo.filename = downloadInfo.filename.replace(/[^\x00-\x7F]+/g, replacementCharacter); // eslint-disable-line  no-control-regex
					return download(downloadInfo, replacementCharacter);
				} else if ((errorMessage.includes(ERROR_INCOGNITO_GECKO) || errorMessage.includes(ERROR_INCOGNITO_GECKO_ALT)) && downloadInfo.incognito) {
					delete downloadInfo.incognito;
					return download(downloadInfo, replacementCharacter);
				} else if (errorMessage == ERROR_CONFLICT_ACTION_GECKO && downloadInfo.conflictAction) {
					delete downloadInfo.conflictAction;
					return download(downloadInfo, replacementCharacter);
				} else if (errorMessage.includes(ERROR_DOWNLOAD_CANCELED_GECKO)) {
					return {};
				} else {
					throw error;
				}
			} else {
				throw error;
			}
		}
		return new Promise((resolve, reject) => {
			browser.downloads.onChanged.addListener(onChanged);

			function onChanged(event) {
				if (event.id == downloadId && event.state) {
					if (event.state.current == STATE_DOWNLOAD_COMPLETE) {
						resolve({});
						browser.downloads.onChanged.removeListener(onChanged);
					}
					if (event.state.current == STATE_DOWNLOAD_INTERRUPTED) {
						if (event.error && event.error.current == STATE_ERROR_CANCELED_CHROMIUM) {
							resolve({});
						} else {
							reject(new Error(event.state.current));
						}
						browser.downloads.onChanged.removeListener(onChanged);
					}
				}
			}
		});
	}

	function saveToClipboard(page) {
		const command = "copy";
		document.addEventListener(command, listener);
		document.execCommand(command);
		document.removeEventListener(command, listener);

		function listener(event) {
			event.clipboardData.setData(MIMETYPE_HTML, page.content);
			event.clipboardData.setData("text/plain", page.content);
			event.preventDefault();
		}
	}

})();
