import eventManager from '../eventManager';
import shim from '../shim';
import { _ } from '../locale';
import keysRegExp from './KeymapService_keysRegExp';
import keycodeToElectronMap from './KeymapService_keycodeToElectronMap';

import BaseService from './BaseService';

const modifiersRegExp = {
	darwin: /^(Ctrl|Option|Shift|Cmd)$/,
	default: /^(Ctrl|Alt|AltGr|Shift|Super)$/,
};

const defaultKeymapItems = {
	darwin: [
		{ accelerator: 'Cmd+N', command: 'newNote' },
		{ accelerator: 'Cmd+T', command: 'newTodo' },
		{ accelerator: 'Cmd+S', command: 'synchronize' },
		{ accelerator: 'Cmd+H', command: 'hideApp' },
		{ accelerator: 'Cmd+Q', command: 'quit' },
		{ accelerator: 'Cmd+,', command: 'config' },
		{ accelerator: 'Cmd+W', command: 'closeWindow' },
		{ accelerator: 'Cmd+C', command: 'textCopy' },
		{ accelerator: 'Cmd+X', command: 'textCut' },
		{ accelerator: 'Cmd+V', command: 'textPaste' },
		{ accelerator: 'Cmd+A', command: 'textSelectAll' },
		{ accelerator: 'Cmd+B', command: 'textBold' },
		{ accelerator: 'Cmd+I', command: 'textItalic' },
		{ accelerator: 'Cmd+K', command: 'textLink' },
		{ accelerator: 'Cmd+`', command: 'textCode' },
		{ accelerator: 'Option+Cmd+-', command: 'textBulletedList' },
		{ accelerator: 'Shift+Cmd+T', command: 'insertDateTime' },
		{ accelerator: 'Shift+Cmd+F', command: 'focusSearch' },
		{ accelerator: 'Cmd+F', command: 'showLocalSearch' },
		{ accelerator: 'Shift+Cmd+S', command: 'focusElementSideBar' },
		{ accelerator: 'Shift+Cmd+L', command: 'focusElementNoteList' },
		{ accelerator: 'Shift+Cmd+N', command: 'focusElementNoteTitle' },
		{ accelerator: 'Shift+Cmd+B', command: 'focusElementNoteBody' },
		{ accelerator: 'Option+Cmd+S', command: 'toggleSideBar' },
		{ accelerator: 'Option+Cmd+L', command: 'toggleNoteList' },
		{ accelerator: 'Cmd+L', command: 'toggleVisiblePanes' },
		{ accelerator: 'Cmd+0', command: 'zoomActualSize' },
		{ accelerator: 'Cmd+E', command: 'toggleExternalEditing' },
		{ accelerator: 'Option+Cmd+T', command: 'setTags' },
		{ accelerator: 'Cmd+P', command: 'gotoAnything' },
		{ accelerator: 'Shift+Cmd+P', command: 'commandPalette' },
		{ accelerator: 'F1', command: 'help' },
		{ accelerator: 'Cmd+D', command: 'editor.deleteLine' },
		{ accelerator: 'Shift+Cmd+D', command: 'editor.duplicateLine' },
		{ accelerator: 'Cmd+Z', command: 'editor.undo' },
		{ accelerator: 'Cmd+Y', command: 'editor.redo' },
		{ accelerator: 'Cmd+[', command: 'editor.indentLess' },
		{ accelerator: 'Cmd+]', command: 'editor.indentMore' },
		{ accelerator: 'Cmd+/', command: 'editor.toggleComment' },
		{ accelerator: 'Option+Cmd+A', command: 'editor.sortSelectedLines' },
		{ accelerator: 'Option+Up', command: 'editor.swapLineUp' },
		{ accelerator: 'Option+Down', command: 'editor.swapLineDown' },
	],
	default: [
		{ accelerator: 'Ctrl+N', command: 'newNote' },
		{ accelerator: 'Ctrl+T', command: 'newTodo' },
		{ accelerator: 'Ctrl+S', command: 'synchronize' },
		{ accelerator: 'Ctrl+Q', command: 'quit' },
		{ accelerator: 'Ctrl+C', command: 'textCopy' },
		{ accelerator: 'Ctrl+X', command: 'textCut' },
		{ accelerator: 'Ctrl+V', command: 'textPaste' },
		{ accelerator: 'Ctrl+A', command: 'textSelectAll' },
		{ accelerator: 'Ctrl+B', command: 'textBold' },
		{ accelerator: 'Ctrl+I', command: 'textItalic' },
		{ accelerator: 'Ctrl+K', command: 'textLink' },
		{ accelerator: 'Ctrl+`', command: 'textCode' },
		{ accelerator: 'Ctrl+Alt+-', command: 'textBulletedList' },
		{ accelerator: 'Ctrl+Shift+T', command: 'insertDateTime' },
		{ accelerator: 'F6', command: 'focusSearch' },
		{ accelerator: 'Ctrl+F', command: 'showLocalSearch' },
		{ accelerator: 'Ctrl+Shift+S', command: 'focusElementSideBar' },
		{ accelerator: 'Ctrl+Shift+L', command: 'focusElementNoteList' },
		{ accelerator: 'Ctrl+Shift+N', command: 'focusElementNoteTitle' },
		{ accelerator: 'Ctrl+Shift+B', command: 'focusElementNoteBody' },
		{ accelerator: 'F10', command: 'toggleSideBar' },
		{ accelerator: 'F11', command: 'toggleNoteList' },
		{ accelerator: 'Ctrl+L', command: 'toggleVisiblePanes' },
		{ accelerator: 'Ctrl+0', command: 'zoomActualSize' },
		{ accelerator: 'Ctrl+E', command: 'toggleExternalEditing' },
		{ accelerator: 'Ctrl+Alt+T', command: 'setTags' },
		{ accelerator: 'Ctrl+,', command: 'config' },
		{ accelerator: 'Ctrl+P', command: 'gotoAnything' },
		{ accelerator: 'Ctrl+Shift+P', command: 'commandPalette' },
		{ accelerator: 'F1', command: 'help' },
		{ accelerator: 'Ctrl+D', command: 'editor.deleteLine' },
		{ accelerator: 'Shift+Ctrl+D', command: 'editor.duplicateLine' },
		{ accelerator: 'Ctrl+Z', command: 'editor.undo' },
		{ accelerator: 'Ctrl+Y', command: 'editor.redo' },
		{ accelerator: 'Ctrl+[', command: 'editor.indentLess' },
		{ accelerator: 'Ctrl+]', command: 'editor.indentMore' },
		{ accelerator: 'Ctrl+/', command: 'editor.toggleComment' },
		{ accelerator: 'Ctrl+Alt+S', command: 'editor.sortSelectedLines' },
		{ accelerator: 'Alt+Up', command: 'editor.swapLineUp' },
		{ accelerator: 'Alt+Down', command: 'editor.swapLineDown' },
	],
};

export interface KeymapItem {
	accelerator: string;
	command: string;
}

interface Keymap {
	[command: string]: KeymapItem;
}

export default class KeymapService extends BaseService {

	private keymap: Keymap;
	private platform: string;
	private customKeymapPath: string;
	private defaultKeymapItems: KeymapItem[];
	private lastSaveTime_: number;
	private modifiersRegExp: any;

	public constructor() {
		super();

		this.lastSaveTime_ = Date.now();
	}

	public get lastSaveTime(): number {
		return this.lastSaveTime_;
	}

	// `additionalDefaultCommandNames` will be added to the default keymap
	// **except** if they are already in it. Basically this is a mechanism
	// to add all the commands from the command service to the default
	// keymap.
	public initialize(additionalDefaultCommandNames: string[] = [], platform: string = shim.platformName()) {
		this.platform = platform;

		switch (platform) {
		case 'darwin':
			this.defaultKeymapItems = defaultKeymapItems.darwin.slice();
			this.modifiersRegExp = modifiersRegExp.darwin;
			break;
		default:
			this.defaultKeymapItems = defaultKeymapItems.default.slice();
			this.modifiersRegExp = modifiersRegExp.default;
		}

		for (const name of additionalDefaultCommandNames) {
			if (this.defaultKeymapItems.find((item: KeymapItem) => item.command === name)) continue;
			this.defaultKeymapItems.push({
				command: name,
				accelerator: null,
			});
		}

		this.resetKeymap();
	}

	// Reset keymap back to its default values
	public resetKeymap() {
		this.keymap = {};
		for (let i = 0; i < this.defaultKeymapItems.length; i++) {
			// Keep the original defaultKeymapItems array untouched
			// Makes it possible to retrieve the original accelerator later, if needed
			this.keymap[this.defaultKeymapItems[i].command] = { ...this.defaultKeymapItems[i] };
		}
	}

	public async loadCustomKeymap(customKeymapPath: string) {
		this.customKeymapPath = customKeymapPath; // Useful for saving the changes later

		if (await shim.fsDriver().exists(customKeymapPath)) {
			this.logger().info(`KeymapService: Loading keymap from file: ${customKeymapPath}`);

			const customKeymapFile = (await shim.fsDriver().readFile(customKeymapPath, 'utf-8')).trim();
			if (!customKeymapFile) return;

			// Custom keymaps are supposed to contain an array of keymap items
			this.overrideKeymap(JSON.parse(customKeymapFile));
		}
	}

	public async saveCustomKeymap(customKeymapPath: string = this.customKeymapPath) {
		this.logger().info(`KeymapService: Saving keymap to file: ${customKeymapPath}`);

		try {
			// Only the customized keymap items should be saved to the disk
			const customKeymapItems = this.getCustomKeymapItems();
			await shim.fsDriver().writeFile(customKeymapPath, JSON.stringify(customKeymapItems, null, 2), 'utf-8');

			this.lastSaveTime_ = Date.now();

			// Refresh the menu items so that the changes are reflected
			eventManager.emit('keymapChange');
		} catch (err) {
			const message = err.message || '';
			throw new Error(_('Error: %s', message));
		}
	}

	public acceleratorExists(command: string) {
		return !!this.keymap[command];
	}

	private convertToPlatform(accelerator: string) {
		return accelerator
			.replace(/CmdOrCtrl/g, this.platform === 'darwin' ? 'Cmd' : 'Ctrl')
			.replace(/Option/g, this.platform === 'darwin' ? 'Option' : 'Alt')
			.replace(/Alt/g, this.platform === 'darwin' ? 'Option' : 'Alt');
	}

	public registerCommandAccelerator(commandName: string, accelerator: string) {
		// If the command is already registered, we don't register it again and
		// we don't update the accelerator. This is because it might have been
		// modified by the user and we don't want the plugin to overwrite this.
		if (this.keymap[commandName]) return;

		if (!commandName) throw new Error('Cannot register an accelerator without a command name');

		const validatedAccelerator = accelerator ? this.convertToPlatform(accelerator) : null;
		if (validatedAccelerator) this.validateAccelerator(validatedAccelerator);

		this.keymap[commandName] = {
			command: commandName,
			accelerator: validatedAccelerator,
		};
	}

	public setAccelerator(command: string, accelerator: string) {
		this.keymap[command].accelerator = accelerator;
	}

	public getAccelerator(command: string) {
		const item = this.keymap[command];
		if (!item) throw new Error(`KeymapService: "${command}" command does not exist!`);

		return item.accelerator;
	}

	public getDefaultAccelerator(command: string) {
		const defaultItem = this.defaultKeymapItems.find((item => item.command === command));
		if (!defaultItem) throw new Error(`KeymapService: "${command}" command does not exist!`);

		return defaultItem.accelerator;
	}

	public getCommandNames() {
		return Object.keys(this.keymap);
	}

	public getKeymapItems() {
		return Object.values(this.keymap);
	}

	public getCustomKeymapItems() {
		const customkeymapItems: KeymapItem[] = [];
		this.defaultKeymapItems.forEach(({ command, accelerator }) => {
			const currentAccelerator = this.getAccelerator(command);

			// Only the customized/changed keymap items are neccessary for the custom keymap
			// Customizations can be merged with the original keymap at the runtime
			if (this.getAccelerator(command) !== accelerator) {
				customkeymapItems.push({ command, accelerator: currentAccelerator });
			}
		});

		for (const commandName in this.keymap) {
			if (!this.defaultKeymapItems.find((item: KeymapItem) => item.command === commandName)) {
				customkeymapItems.push(this.keymap[commandName]);
			}
		}

		return customkeymapItems;
	}

	public getDefaultKeymapItems() {
		return [...this.defaultKeymapItems];
	}

	public overrideKeymap(customKeymapItems: KeymapItem[]) {
		try {
			for (let i = 0; i < customKeymapItems.length; i++) {
				const item = customKeymapItems[i];
				// Validate individual custom keymap items
				// Throws if there are any issues in the keymap item
				this.validateKeymapItem(item);

				// If the command does not exist in the keymap, we are loading a new
				// command accelerator so we need to register it.
				if (!this.keymap[item.command]) {
					this.registerCommandAccelerator(item.command, item.accelerator);
				} else {
					this.setAccelerator(item.command, item.accelerator);
				}
			}

			// Validate the entire keymap for duplicates
			// Throws whenever there are duplicate Accelerators used in the keymap
			this.validateKeymap();
		} catch (err) {
			this.resetKeymap(); // Discard all the changes if there are any issues
			throw err;
		}
	}

	private validateKeymapItem(item: KeymapItem) {
		if (!item.hasOwnProperty('command')) {
			throw new Error(_('"%s" is missing the required "%s" property.', JSON.stringify(item), _('command')));
		// } else if (!this.keymap.hasOwnProperty(item.command)) {
		// 	throw new Error(_('Invalid %s: %s.', _('command'), item.command));
		}

		if (!item.hasOwnProperty('accelerator')) {
			throw new Error(_('"%s" is missing the required "%s" property.', JSON.stringify(item), _('accelerator')));
		} else if (item.accelerator !== null) {
			try {
				this.validateAccelerator(item.accelerator);
			} catch {
				throw new Error(_('Invalid %s: %s.', _('accelerator'), item.command));
			}
		}
	}

	public validateKeymap(proposedKeymapItem: KeymapItem = null) {
		const usedAccelerators = new Set();

		// Validate as if the proposed change is already present in the current keymap
		// Helpful for detecting any errors that'll occur, when the proposed change is performed on the keymap
		if (proposedKeymapItem) usedAccelerators.add(proposedKeymapItem.accelerator);

		for (const item of Object.values(this.keymap)) {
			const [itemAccelerator, itemCommand] = [item.accelerator, item.command];
			if (proposedKeymapItem && itemCommand === proposedKeymapItem.command) continue; // Ignore the original accelerator

			if (usedAccelerators.has(itemAccelerator)) {
				const originalItem = (proposedKeymapItem && proposedKeymapItem.accelerator === itemAccelerator)
					? proposedKeymapItem
					: Object.values(this.keymap).find(_item => _item.accelerator == itemAccelerator);

				throw new Error(_(
					'Accelerator "%s" is used for "%s" and "%s" commands. This may lead to unexpected behaviour.',
					itemAccelerator,
					originalItem.command,
					itemCommand
				));
			} else if (itemAccelerator) {
				usedAccelerators.add(itemAccelerator);
			}
		}
	}

	public validateAccelerator(accelerator: string) {
		let keyFound = false;

		const parts = accelerator.split('+');
		const isValid = parts.every((part, index) => {
			const isKey = keysRegExp.test(part);
			const isModifier = this.modifiersRegExp.test(part);

			if (isKey) {
				// Key must be unique
				if (keyFound) return false;
				keyFound = true;
			}

			// Key is required
			if (index === (parts.length - 1) && !keyFound) return false;
			return isKey || isModifier;
		});

		if (!isValid) throw new Error(_('Accelerator "%s" is not valid.', accelerator));
	}

	public domToElectronAccelerator(event: any) {
		const parts = [];

		// We use the "keyCode" and not "key" because the modifier keys
		// would change the "key" value. eg "Option+U" would give "º" as a key instead of "U"
		const { keyCode, ctrlKey, metaKey, altKey, shiftKey } = event;

		// First, the modifiers
		// We have to use the following js events, because modifiers won't stick otherwise
		if (ctrlKey) parts.push('Ctrl');
		switch (this.platform) {
		case 'darwin':
			if (altKey) parts.push('Option');
			if (shiftKey) parts.push('Shift');
			if (metaKey) parts.push('Cmd');
			break;
		default:
			if (altKey) parts.push('Alt');
			if (shiftKey) parts.push('Shift');
		}

		// Finally, the key
		// String.fromCharCode expects unicode charcodes as an argument; e.keyCode returns javascript keycodes.
		// Javascript keycodes and unicode charcodes are not the same thing!
		const electronKey = keycodeToElectronMap[keyCode];
		if (electronKey && keysRegExp.test(electronKey)) parts.push(electronKey);

		return parts.join('+');
	}

	public on(eventName: string, callback: Function) {
		eventManager.on(eventName, callback);
	}

	public off(eventName: string, callback: Function) {
		eventManager.off(eventName, callback);
	}

	private static instance_: KeymapService = null;

	public static destroyInstance() {
		this.instance_ = null;
	}

	public static instance(): KeymapService {
		if (this.instance_) return this.instance_;

		this.instance_ = new KeymapService();
		return this.instance_;
	}
}