/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/

import { window, workspace, Disposable, TextDocument, Position, SnippetString, TextDocumentChangeEvent, TextDocumentChangeReason, TextDocumentContentChangeEvent } from 'vscode';
import { Runtime } from './htmlClient';
import { LanguageParticipants } from './languageParticipants';

export function activateAutoInsertion(provider: (kind: 'autoQuote' | 'autoClose', document: TextDocument, position: Position) => Thenable<string | null>, languageParticipants: LanguageParticipants, runtime: Runtime): Disposable {
	const disposables: Disposable[] = [];
	workspace.onDidChangeTextDocument(onDidChangeTextDocument, null, disposables);

	let anyIsEnabled = false;
	const isEnabled = {
		'autoQuote': false,
		'autoClose': false
	};
	updateEnabledState();
	window.onDidChangeActiveTextEditor(updateEnabledState, null, disposables);

	let timeout: Disposable | undefined = undefined;

	disposables.push({
		dispose: () => {
			timeout?.dispose();
		}
	});

	function updateEnabledState() {
		anyIsEnabled = false;
		const editor = window.activeTextEditor;
		if (!editor) {
			return;
		}
		const document = editor.document;
		if (!languageParticipants.useAutoInsert(document.languageId)) {
			return;
		}
		const configurations = workspace.getConfiguration(undefined, document.uri);
		isEnabled['autoQuote'] = configurations.get<boolean>('html.autoCreateQuotes') ?? false;
		isEnabled['autoClose'] = configurations.get<boolean>('html.autoClosingTags') ?? false;
		anyIsEnabled = isEnabled['autoQuote'] || isEnabled['autoClose'];
	}

	function onDidChangeTextDocument({ document, contentChanges, reason }: TextDocumentChangeEvent) {
		if (!anyIsEnabled || contentChanges.length === 0 || reason === TextDocumentChangeReason.Undo || reason === TextDocumentChangeReason.Redo) {
			return;
		}
		const activeDocument = window.activeTextEditor && window.activeTextEditor.document;
		if (document !== activeDocument) {
			return;
		}
		if (timeout) {
			timeout.dispose();
		}

		const lastChange = contentChanges[contentChanges.length - 1];
		if (lastChange.rangeLength === 0 && isSingleLine(lastChange.text)) {
			const lastCharacter = lastChange.text[lastChange.text.length - 1];
			if (isEnabled['autoQuote'] && lastCharacter === '=') {
				doAutoInsert('autoQuote', document, lastChange);
			} else if (isEnabled['autoClose'] && (lastCharacter === '>' || lastCharacter === '/')) {
				doAutoInsert('autoClose', document, lastChange);
			}
		}
	}

	function isSingleLine(text: string): boolean {
		return !/\n/.test(text);
	}

	function doAutoInsert(kind: 'autoQuote' | 'autoClose', document: TextDocument, lastChange: TextDocumentContentChangeEvent) {
		const rangeStart = lastChange.range.start;
		const version = document.version;
		timeout = runtime.timer.setTimeout(() => {
			const position = new Position(rangeStart.line, rangeStart.character + lastChange.text.length);
			provider(kind, document, position).then(text => {
				if (text && isEnabled[kind]) {
					const activeEditor = window.activeTextEditor;
					if (activeEditor) {
						const activeDocument = activeEditor.document;
						if (document === activeDocument && activeDocument.version === version) {
							const selections = activeEditor.selections;
							if (selections.length && selections.some(s => s.active.isEqual(position))) {
								activeEditor.insertSnippet(new SnippetString(text), selections.map(s => s.active));
							} else {
								activeEditor.insertSnippet(new SnippetString(text), position);
							}
						}
					}
				}
			});
			timeout = undefined;
		}, 100);
	}
	return Disposable.from(...disposables);
}