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

import * as vscode from 'vscode';
import type * as Proto from '../protocol';
import { ITypeScriptServiceClient, ClientCapability } from '../typescriptService';
import API from '../utils/api';
import { coalesce } from '../utils/arrays';
import { Delayer } from '../utils/async';
import { nulToken } from '../utils/cancellation';
import { Disposable } from '../utils/dispose';
import * as languageModeIds from '../utils/languageModeIds';
import { ResourceMap } from '../utils/resourceMap';
import * as typeConverters from '../utils/typeConverters';

const enum BufferKind {
	TypeScript = 1,
	JavaScript = 2,
}

const enum BufferState {
	Initial = 1,
	Open = 2,
	Closed = 2,
}

function mode2ScriptKind(mode: string): 'TS' | 'TSX' | 'JS' | 'JSX' | undefined {
	switch (mode) {
		case languageModeIds.typescript: return 'TS';
		case languageModeIds.typescriptreact: return 'TSX';
		case languageModeIds.javascript: return 'JS';
		case languageModeIds.javascriptreact: return 'JSX';
	}
	return undefined;
}

const enum BufferOperationType { Close, Open, Change }

class CloseOperation {
	readonly type = BufferOperationType.Close;
	constructor(
		public readonly args: string
	) { }
}

class OpenOperation {
	readonly type = BufferOperationType.Open;
	constructor(
		public readonly args: Proto.OpenRequestArgs
	) { }
}

class ChangeOperation {
	readonly type = BufferOperationType.Change;
	constructor(
		public readonly args: Proto.FileCodeEdits
	) { }
}

type BufferOperation = CloseOperation | OpenOperation | ChangeOperation;

/**
 * Manages synchronization of buffers with the TS server.
 *
 * If supported, batches together file changes. This allows the TS server to more efficiently process changes.
 */
class BufferSynchronizer {

	private readonly _pending: ResourceMap<BufferOperation>;

	constructor(
		private readonly client: ITypeScriptServiceClient,
		onCaseInsenitiveFileSystem: boolean
	) {
		this._pending = new ResourceMap<BufferOperation>(undefined, {
			onCaseInsenitiveFileSystem
		});
	}

	public open(resource: vscode.Uri, args: Proto.OpenRequestArgs) {
		if (this.supportsBatching) {
			this.updatePending(resource, new OpenOperation(args));
		} else {
			this.client.executeWithoutWaitingForResponse('open', args);
		}
	}

	/**
	 * @return Was the buffer open?
	 */
	public close(resource: vscode.Uri, filepath: string): boolean {
		if (this.supportsBatching) {
			return this.updatePending(resource, new CloseOperation(filepath));
		} else {
			const args: Proto.FileRequestArgs = { file: filepath };
			this.client.executeWithoutWaitingForResponse('close', args);
			return true;
		}
	}

	public change(resource: vscode.Uri, filepath: string, events: readonly vscode.TextDocumentContentChangeEvent[]) {
		if (!events.length) {
			return;
		}

		if (this.supportsBatching) {
			this.updatePending(resource, new ChangeOperation({
				fileName: filepath,
				textChanges: events.map((change): Proto.CodeEdit => ({
					newText: change.text,
					start: typeConverters.Position.toLocation(change.range.start),
					end: typeConverters.Position.toLocation(change.range.end),
				})).reverse(), // Send the edits end-of-document to start-of-document order
			}));
		} else {
			for (const { range, text } of events) {
				const args: Proto.ChangeRequestArgs = {
					insertString: text,
					...typeConverters.Range.toFormattingRequestArgs(filepath, range)
				};
				this.client.executeWithoutWaitingForResponse('change', args);
			}
		}
	}

	public reset(): void {
		this._pending.clear();
	}

	public beforeCommand(command: string): void {
		if (command === 'updateOpen') {
			return;
		}

		this.flush();
	}

	private flush() {
		if (!this.supportsBatching) {
			// We've already eagerly synchronized
			this._pending.clear();
			return;
		}

		if (this._pending.size > 0) {
			const closedFiles: string[] = [];
			const openFiles: Proto.OpenRequestArgs[] = [];
			const changedFiles: Proto.FileCodeEdits[] = [];
			for (const change of this._pending.values) {
				switch (change.type) {
					case BufferOperationType.Change: changedFiles.push(change.args); break;
					case BufferOperationType.Open: openFiles.push(change.args); break;
					case BufferOperationType.Close: closedFiles.push(change.args); break;
				}
			}
			this.client.execute('updateOpen', { changedFiles, closedFiles, openFiles }, nulToken, { nonRecoverable: true });
			this._pending.clear();
		}
	}

	private get supportsBatching(): boolean {
		return this.client.apiVersion.gte(API.v340);
	}

	private updatePending(resource: vscode.Uri, op: BufferOperation): boolean {
		switch (op.type) {
			case BufferOperationType.Close:
				const existing = this._pending.get(resource);
				switch (existing?.type) {
					case BufferOperationType.Open:
						this._pending.delete(resource);
						return false; // Open then close. No need to do anything
				}
				break;
		}

		if (this._pending.has(resource)) {
			// we saw this file before, make sure we flush before working with it again
			this.flush();
		}
		this._pending.set(resource, op);
		return true;
	}
}

class SyncedBuffer {

	private state = BufferState.Initial;

	constructor(
		private readonly document: vscode.TextDocument,
		public readonly filepath: string,
		private readonly client: ITypeScriptServiceClient,
		private readonly synchronizer: BufferSynchronizer,
	) { }

	public open(): void {
		const args: Proto.OpenRequestArgs = {
			file: this.filepath,
			fileContent: this.document.getText(),
			projectRootPath: this.client.getWorkspaceRootForResource(this.document.uri),
		};

		const scriptKind = mode2ScriptKind(this.document.languageId);
		if (scriptKind) {
			args.scriptKindName = scriptKind;
		}

		if (this.client.apiVersion.gte(API.v240)) {
			const tsPluginsForDocument = this.client.pluginManager.plugins
				.filter(x => x.languages.indexOf(this.document.languageId) >= 0);

			if (tsPluginsForDocument.length) {
				(args as any).plugins = tsPluginsForDocument.map(plugin => plugin.name);
			}
		}

		this.synchronizer.open(this.resource, args);
		this.state = BufferState.Open;
	}

	public get resource(): vscode.Uri {
		return this.document.uri;
	}

	public get lineCount(): number {
		return this.document.lineCount;
	}

	public get kind(): BufferKind {
		switch (this.document.languageId) {
			case languageModeIds.javascript:
			case languageModeIds.javascriptreact:
				return BufferKind.JavaScript;

			case languageModeIds.typescript:
			case languageModeIds.typescriptreact:
			default:
				return BufferKind.TypeScript;
		}
	}

	/**
	 * @return Was the buffer open?
	 */
	public close(): boolean {
		if (this.state !== BufferState.Open) {
			this.state = BufferState.Closed;
			return false;
		}
		this.state = BufferState.Closed;
		return this.synchronizer.close(this.resource, this.filepath);
	}

	public onContentChanged(events: readonly vscode.TextDocumentContentChangeEvent[]): void {
		if (this.state !== BufferState.Open) {
			console.error(`Unexpected buffer state: ${this.state}`);
		}

		this.synchronizer.change(this.resource, this.filepath, events);
	}
}

class SyncedBufferMap extends ResourceMap<SyncedBuffer> {

	public getForPath(filePath: string): SyncedBuffer | undefined {
		return this.get(vscode.Uri.file(filePath));
	}

	public get allBuffers(): Iterable<SyncedBuffer> {
		return this.values;
	}
}

class PendingDiagnostics extends ResourceMap<number> {
	public getOrderedFileSet(): ResourceMap<void> {
		const orderedResources = Array.from(this.entries)
			.sort((a, b) => a.value - b.value)
			.map(entry => entry.resource);

		const map = new ResourceMap<void>(undefined, this.config);
		for (const resource of orderedResources) {
			map.set(resource, undefined);
		}
		return map;
	}
}

class GetErrRequest {

	public static executeGetErrRequest(
		client: ITypeScriptServiceClient,
		files: ResourceMap<void>,
		onDone: () => void
	) {
		return new GetErrRequest(client, files, onDone);
	}

	private _done: boolean = false;
	private readonly _token: vscode.CancellationTokenSource = new vscode.CancellationTokenSource();

	private constructor(
		client: ITypeScriptServiceClient,
		public readonly files: ResourceMap<void>,
		onDone: () => void
	) {
		const allFiles = coalesce(Array.from(files.entries).map(entry => client.normalizedPath(entry.resource)));
		if (!allFiles.length || !client.capabilities.has(ClientCapability.Semantic)) {
			this._done = true;
			setImmediate(onDone);
		} else {
			const request = client.configuration.enableProjectDiagnostics
				// Note that geterrForProject is almost certainly not the api we want here as it ends up computing far
				// too many diagnostics
				? client.executeAsync('geterrForProject', { delay: 0, file: allFiles[0] }, this._token.token)
				: client.executeAsync('geterr', { delay: 0, files: allFiles }, this._token.token);

			request.finally(() => {
				if (this._done) {
					return;
				}
				this._done = true;
				onDone();
			});
		}
	}

	public cancel(): any {
		if (!this._done) {
			this._token.cancel();
		}

		this._token.dispose();
	}
}

export default class BufferSyncSupport extends Disposable {

	private readonly client: ITypeScriptServiceClient;

	private _validateJavaScript: boolean = true;
	private _validateTypeScript: boolean = true;
	private readonly modeIds: Set<string>;
	private readonly syncedBuffers: SyncedBufferMap;
	private readonly pendingDiagnostics: PendingDiagnostics;
	private readonly diagnosticDelayer: Delayer<any>;
	private pendingGetErr: GetErrRequest | undefined;
	private listening: boolean = false;
	private readonly synchronizer: BufferSynchronizer;

	constructor(
		client: ITypeScriptServiceClient,
		modeIds: readonly string[],
		onCaseInsenitiveFileSystem: boolean
	) {
		super();
		this.client = client;
		this.modeIds = new Set<string>(modeIds);

		this.diagnosticDelayer = new Delayer<any>(300);

		const pathNormalizer = (path: vscode.Uri) => this.client.normalizedPath(path);
		this.syncedBuffers = new SyncedBufferMap(pathNormalizer, { onCaseInsenitiveFileSystem });
		this.pendingDiagnostics = new PendingDiagnostics(pathNormalizer, { onCaseInsenitiveFileSystem });
		this.synchronizer = new BufferSynchronizer(client, onCaseInsenitiveFileSystem);

		this.updateConfiguration();
		vscode.workspace.onDidChangeConfiguration(this.updateConfiguration, this, this._disposables);
	}

	private readonly _onDelete = this._register(new vscode.EventEmitter<vscode.Uri>());
	public readonly onDelete = this._onDelete.event;

	private readonly _onWillChange = this._register(new vscode.EventEmitter<vscode.Uri>());
	public readonly onWillChange = this._onWillChange.event;

	public listen(): void {
		if (this.listening) {
			return;
		}
		this.listening = true;
		vscode.workspace.onDidOpenTextDocument(this.openTextDocument, this, this._disposables);
		vscode.workspace.onDidCloseTextDocument(this.onDidCloseTextDocument, this, this._disposables);
		vscode.workspace.onDidChangeTextDocument(this.onDidChangeTextDocument, this, this._disposables);
		vscode.window.onDidChangeVisibleTextEditors(e => {
			for (const { document } of e) {
				const syncedBuffer = this.syncedBuffers.get(document.uri);
				if (syncedBuffer) {
					this.requestDiagnostic(syncedBuffer);
				}
			}
		}, this, this._disposables);
		vscode.workspace.textDocuments.forEach(this.openTextDocument, this);
	}

	public handles(resource: vscode.Uri): boolean {
		return this.syncedBuffers.has(resource);
	}

	public ensureHasBuffer(resource: vscode.Uri): boolean {
		if (this.syncedBuffers.has(resource)) {
			return true;
		}

		const existingDocument = vscode.workspace.textDocuments.find(doc => doc.uri.toString() === resource.toString());
		if (existingDocument) {
			return this.openTextDocument(existingDocument);
		}

		return false;
	}

	public toVsCodeResource(resource: vscode.Uri): vscode.Uri {
		const filepath = this.client.normalizedPath(resource);
		for (const buffer of this.syncedBuffers.allBuffers) {
			if (buffer.filepath === filepath) {
				return buffer.resource;
			}
		}
		return resource;
	}

	public toResource(filePath: string): vscode.Uri {
		const buffer = this.syncedBuffers.getForPath(filePath);
		if (buffer) {
			return buffer.resource;
		}
		return vscode.Uri.file(filePath);
	}

	public reset(): void {
		this.pendingGetErr?.cancel();
		this.pendingDiagnostics.clear();
		this.synchronizer.reset();
	}

	public reinitialize(): void {
		this.reset();
		for (const buffer of this.syncedBuffers.allBuffers) {
			buffer.open();
		}
	}

	public openTextDocument(document: vscode.TextDocument): boolean {
		if (!this.modeIds.has(document.languageId)) {
			return false;
		}
		const resource = document.uri;
		const filepath = this.client.normalizedPath(resource);
		if (!filepath) {
			return false;
		}

		if (this.syncedBuffers.has(resource)) {
			return true;
		}

		const syncedBuffer = new SyncedBuffer(document, filepath, this.client, this.synchronizer);
		this.syncedBuffers.set(resource, syncedBuffer);
		syncedBuffer.open();
		this.requestDiagnostic(syncedBuffer);
		return true;
	}

	public closeResource(resource: vscode.Uri): void {
		const syncedBuffer = this.syncedBuffers.get(resource);
		if (!syncedBuffer) {
			return;
		}
		this.pendingDiagnostics.delete(resource);
		this.pendingGetErr?.files.delete(resource);
		this.syncedBuffers.delete(resource);
		const wasBufferOpen = syncedBuffer.close();
		this._onDelete.fire(resource);
		if (wasBufferOpen) {
			this.requestAllDiagnostics();
		}
	}

	public interuptGetErr<R>(f: () => R): R {
		if (!this.pendingGetErr
			|| this.client.configuration.enableProjectDiagnostics // `geterr` happens on seperate server so no need to cancel it.
		) {
			return f();
		}

		this.pendingGetErr.cancel();
		this.pendingGetErr = undefined;
		const result = f();
		this.triggerDiagnostics();
		return result;
	}

	public beforeCommand(command: string): void {
		this.synchronizer.beforeCommand(command);
	}

	private onDidCloseTextDocument(document: vscode.TextDocument): void {
		this.closeResource(document.uri);
	}

	private onDidChangeTextDocument(e: vscode.TextDocumentChangeEvent): void {
		const syncedBuffer = this.syncedBuffers.get(e.document.uri);
		if (!syncedBuffer) {
			return;
		}

		this._onWillChange.fire(syncedBuffer.resource);

		syncedBuffer.onContentChanged(e.contentChanges);
		const didTrigger = this.requestDiagnostic(syncedBuffer);

		if (!didTrigger && this.pendingGetErr) {
			// In this case we always want to re-trigger all diagnostics
			this.pendingGetErr.cancel();
			this.pendingGetErr = undefined;
			this.triggerDiagnostics();
		}
	}

	public requestAllDiagnostics() {
		for (const buffer of this.syncedBuffers.allBuffers) {
			if (this.shouldValidate(buffer)) {
				this.pendingDiagnostics.set(buffer.resource, Date.now());
			}
		}
		this.triggerDiagnostics();
	}

	public getErr(resources: vscode.Uri[]): any {
		const handledResources = resources.filter(resource => this.handles(resource));
		if (!handledResources.length) {
			return;
		}

		for (const resource of handledResources) {
			this.pendingDiagnostics.set(resource, Date.now());
		}

		this.triggerDiagnostics();
	}

	private triggerDiagnostics(delay: number = 200) {
		this.diagnosticDelayer.trigger(() => {
			this.sendPendingDiagnostics();
		}, delay);
	}

	private requestDiagnostic(buffer: SyncedBuffer): boolean {
		if (!this.shouldValidate(buffer)) {
			return false;
		}

		this.pendingDiagnostics.set(buffer.resource, Date.now());

		const delay = Math.min(Math.max(Math.ceil(buffer.lineCount / 20), 300), 800);
		this.triggerDiagnostics(delay);
		return true;
	}

	public hasPendingDiagnostics(resource: vscode.Uri): boolean {
		return this.pendingDiagnostics.has(resource);
	}

	private sendPendingDiagnostics(): void {
		const orderedFileSet = this.pendingDiagnostics.getOrderedFileSet();

		if (this.pendingGetErr) {
			this.pendingGetErr.cancel();

			for (const { resource } of this.pendingGetErr.files.entries) {
				if (this.syncedBuffers.get(resource)) {
					orderedFileSet.set(resource, undefined);
				}
			}

			this.pendingGetErr = undefined;
		}

		// Add all open TS buffers to the geterr request. They might be visible
		for (const buffer of this.syncedBuffers.values) {
			orderedFileSet.set(buffer.resource, undefined);
		}

		if (orderedFileSet.size) {
			const getErr = this.pendingGetErr = GetErrRequest.executeGetErrRequest(this.client, orderedFileSet, () => {
				if (this.pendingGetErr === getErr) {
					this.pendingGetErr = undefined;
				}
			});
		}

		this.pendingDiagnostics.clear();
	}

	private updateConfiguration() {
		const jsConfig = vscode.workspace.getConfiguration('javascript', null);
		const tsConfig = vscode.workspace.getConfiguration('typescript', null);

		this._validateJavaScript = jsConfig.get<boolean>('validate.enable', true);
		this._validateTypeScript = tsConfig.get<boolean>('validate.enable', true);
	}

	private shouldValidate(buffer: SyncedBuffer) {
		switch (buffer.kind) {
			case BufferKind.JavaScript:
				return this._validateJavaScript;

			case BufferKind.TypeScript:
			default:
				return this._validateTypeScript;
		}
	}
}
