'use strict';
import { TextDecoder } from 'util';
import {
	commands,
	ConfigurationChangeEvent,
	ConfigurationTarget,
	Disposable,
	Uri,
	ViewColumn,
	Webview,
	WebviewPanel,
	WebviewPanelOnDidChangeViewStateEvent,
	window,
	workspace,
} from 'vscode';
import { configuration } from '../configuration';
import { Container } from '../container';
import { Logger } from '../logger';
import {
	DidChangeConfigurationNotificationType,
	IpcMessage,
	IpcNotificationParamsOf,
	IpcNotificationType,
	onIpcCommand,
	UpdateConfigurationCommandType,
} from './protocol';
import { Commands } from '../commands';

let ipcSequence = 0;
function nextIpcId() {
	if (ipcSequence === Number.MAX_SAFE_INTEGER) {
		ipcSequence = 1;
	} else {
		ipcSequence++;
	}

	return `host:${ipcSequence}`;
}

const emptyCommands: Disposable[] = [
	{
		dispose: function () {
			/* noop */
		},
	},
];

export abstract class WebviewBase implements Disposable {
	protected disposable: Disposable;
	private _disposablePanel: Disposable | undefined;
	private _panel: WebviewPanel | undefined;

	constructor(showCommand: Commands, private readonly _column?: ViewColumn) {
		this.disposable = Disposable.from(
			configuration.onDidChange(this.onConfigurationChanged, this),
			commands.registerCommand(showCommand, this.onShowCommand, this),
		);
	}

	abstract get filename(): string;
	abstract get id(): string;
	abstract get title(): string;

	registerCommands(): Disposable[] {
		return emptyCommands;
	}

	renderHead?(): string | Promise<string>;
	renderBody?(): string | Promise<string>;
	renderEndOfBody?(): string | Promise<string>;

	dispose() {
		this.disposable.dispose();
		this._disposablePanel?.dispose();
	}

	protected onShowCommand() {
		void this.show(this._column);
	}

	private onConfigurationChanged(_e: ConfigurationChangeEvent) {
		void this.notifyDidChangeConfiguration();
	}

	private onPanelDisposed() {
		this._disposablePanel?.dispose();
		this._panel = undefined;
	}

	private onViewStateChanged(e: WebviewPanelOnDidChangeViewStateEvent) {
		Logger.log(
			`Webview(${this.id}).onViewStateChanged`,
			`active=${e.webviewPanel.active}, visible=${e.webviewPanel.visible}`,
		);

		// Anytime the webview becomes active, make sure it has the most up-to-date config
		if (e.webviewPanel.active) {
			void this.notifyDidChangeConfiguration();
		}
	}

	protected onMessageReceived(e: IpcMessage) {
		switch (e.method) {
			case UpdateConfigurationCommandType.method:
				onIpcCommand(UpdateConfigurationCommandType, e, async params => {
					const target =
						params.scope === 'workspace' ? ConfigurationTarget.Workspace : ConfigurationTarget.Global;

					for (const key in params.changes) {
						const inspect = configuration.inspect(key as any)!;

						let value = params.changes[key];
						if (value != null) {
							if (params.scope === 'workspace') {
								if (value === inspect.workspaceValue) continue;
							} else {
								if (value === inspect.globalValue && value !== inspect.defaultValue) continue;

								if (value === inspect.defaultValue) {
									value = undefined;
								}
							}
						}

						void (await configuration.update(key as any, value, target));
					}

					for (const key of params.removes) {
						void (await configuration.update(key as any, undefined, target));
					}
				});

				break;
			default:
				break;
		}
	}

	private onMessageReceivedCore(e: IpcMessage) {
		if (e == null) return;

		Logger.log(`Webview(${this.id}).onMessageReceived: method=${e.method}, data=${JSON.stringify(e)}`);

		this.onMessageReceived(e);
	}

	get visible() {
		return this._panel?.visible ?? false;
	}

	hide() {
		this._panel?.dispose();
	}

	setTitle(title: string) {
		if (this._panel == null) return;

		this._panel.title = title;
	}

	async show(column: ViewColumn = ViewColumn.Beside): Promise<void> {
		if (this._panel == null) {
			this._panel = window.createWebviewPanel(
				this.id,
				this.title,
				{ viewColumn: column, preserveFocus: false },
				{
					retainContextWhenHidden: true,
					enableFindWidget: true,
					enableCommandUris: true,
					enableScripts: true,
				},
			);

			this._panel.iconPath = Uri.file(Container.context.asAbsolutePath('images/gitlens-icon.png'));
			this._disposablePanel = Disposable.from(
				this._panel,
				this._panel.onDidDispose(this.onPanelDisposed, this),
				this._panel.onDidChangeViewState(this.onViewStateChanged, this),
				this._panel.webview.onDidReceiveMessage(this.onMessageReceivedCore, this),
				...this.registerCommands(),
			);

			this._panel.webview.html = await this.getHtml(this._panel.webview);
		} else {
			const html = await this.getHtml(this._panel.webview);

			// Reset the html to get the webview to reload
			this._panel.webview.html = '';
			this._panel.webview.html = html;

			this._panel.reveal(this._panel.viewColumn ?? ViewColumn.Active, false);
		}
	}

	private async getHtml(webview: Webview): Promise<string> {
		const uri = Uri.joinPath(Container.context.extensionUri, 'dist', 'webviews', this.filename);
		const content = new TextDecoder('utf8').decode(await workspace.fs.readFile(uri));

		let html = content
			.replace(/#{cspSource}/g, webview.cspSource)
			.replace(/#{root}/g, webview.asWebviewUri(Container.context.extensionUri).toString());

		if (this.renderHead != null) {
			html = html.replace(/#{head}/i, await this.renderHead());
		}

		if (this.renderBody != null) {
			html = html.replace(/#{body}/i, await this.renderBody());
		}

		if (this.renderEndOfBody != null) {
			html = html.replace(/#{endOfBody}/i, await this.renderEndOfBody());
		}

		return html;
	}

	protected notify<NT extends IpcNotificationType>(type: NT, params: IpcNotificationParamsOf<NT>): Thenable<boolean> {
		return this.postMessage({ id: nextIpcId(), method: type.method, params: params });
	}

	private notifyDidChangeConfiguration() {
		// Make sure to get the raw config, not from the container which has the modes mixed in
		return this.notify(DidChangeConfigurationNotificationType, { config: configuration.get() });
	}

	private postMessage(message: IpcMessage) {
		if (this._panel == null) return Promise.resolve(false);

		return this._panel.webview.postMessage(message);
	}
}