/*---------------------------------------------------------------------------------------------
 *  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 { EventName } from '../protocol.const';
import { CallbackMap } from '../tsServer/callbackMap';
import { RequestItem, RequestQueue, RequestQueueingType } from '../tsServer/requestQueue';
import { TypeScriptServerError } from '../tsServer/serverError';
import { ServerResponse, ServerType, TypeScriptRequests } from '../typescriptService';
import { TypeScriptServiceConfiguration } from '../utils/configuration';
import { Disposable } from '../utils/dispose';
import { TelemetryReporter } from '../utils/telemetry';
import Tracer from '../utils/tracer';
import { OngoingRequestCanceller } from './cancellation';
import { TypeScriptVersionManager } from './versionManager';
import { TypeScriptVersion } from './versionProvider';

export enum ExecutionTarget {
	Semantic,
	Syntax
}

export interface ITypeScriptServer {
	readonly onEvent: vscode.Event<Proto.Event>;
	readonly onExit: vscode.Event<any>;
	readonly onError: vscode.Event<any>;

	readonly tsServerLogFile: string | undefined;

	kill(): void;

	executeImpl(command: keyof TypeScriptRequests, args: any, executeInfo: { isAsync: boolean, token?: vscode.CancellationToken, expectsResult: false, lowPriority?: boolean, executionTarget?: ExecutionTarget }): undefined;
	executeImpl(command: keyof TypeScriptRequests, args: any, executeInfo: { isAsync: boolean, token?: vscode.CancellationToken, expectsResult: boolean, lowPriority?: boolean, executionTarget?: ExecutionTarget }): Promise<ServerResponse.Response<Proto.Response>>;
	executeImpl(command: keyof TypeScriptRequests, args: any, executeInfo: { isAsync: boolean, token?: vscode.CancellationToken, expectsResult: boolean, lowPriority?: boolean, executionTarget?: ExecutionTarget }): Promise<ServerResponse.Response<Proto.Response>> | undefined;

	dispose(): void;
}

export interface TsServerDelegate {
	onFatalError(command: string, error: Error): void;
}

export const enum TsServerProcessKind {
	Main = 'main',
	Syntax = 'syntax',
	Semantic = 'semantic',
	Diagnostics = 'diagnostics'
}

export interface TsServerProcessFactory {
	fork(
		tsServerPath: string,
		args: readonly string[],
		kind: TsServerProcessKind,
		configuration: TypeScriptServiceConfiguration,
		versionManager: TypeScriptVersionManager,
	): TsServerProcess;
}

export interface TsServerProcess {
	write(serverRequest: Proto.Request): void;

	onData(handler: (data: Proto.Response) => void): void;
	onExit(handler: (code: number | null) => void): void;
	onError(handler: (error: Error) => void): void;

	kill(): void;
}

export class ProcessBasedTsServer extends Disposable implements ITypeScriptServer {
	private readonly _requestQueue = new RequestQueue();
	private readonly _callbacks = new CallbackMap<Proto.Response>();
	private readonly _pendingResponses = new Set<number>();

	constructor(
		private readonly _serverId: string,
		private readonly _serverSource: ServerType,
		private readonly _process: TsServerProcess,
		private readonly _tsServerLogFile: string | undefined,
		private readonly _requestCanceller: OngoingRequestCanceller,
		private readonly _version: TypeScriptVersion,
		private readonly _telemetryReporter: TelemetryReporter,
		private readonly _tracer: Tracer,
	) {
		super();

		this._process.onData(msg => {
			this.dispatchMessage(msg);
		});

		this._process.onExit(code => {
			this._onExit.fire(code);
			this._callbacks.destroy('server exited');
		});

		this._process.onError(error => {
			this._onError.fire(error);
			this._callbacks.destroy('server errored');
		});
	}

	private readonly _onEvent = this._register(new vscode.EventEmitter<Proto.Event>());
	public readonly onEvent = this._onEvent.event;

	private readonly _onExit = this._register(new vscode.EventEmitter<any>());
	public readonly onExit = this._onExit.event;

	private readonly _onError = this._register(new vscode.EventEmitter<any>());
	public readonly onError = this._onError.event;

	public get tsServerLogFile() { return this._tsServerLogFile; }

	private write(serverRequest: Proto.Request) {
		this._process.write(serverRequest);
	}

	public override dispose() {
		super.dispose();
		this._callbacks.destroy('server disposed');
		this._pendingResponses.clear();
	}

	public kill() {
		this._process.kill();
	}

	private dispatchMessage(message: Proto.Message) {
		try {
			switch (message.type) {
				case 'response':
					if (this._serverSource) {
						this.dispatchResponse({
							...(message as Proto.Response),
							_serverType: this._serverSource
						});
					} else {
						this.dispatchResponse(message as Proto.Response);
					}
					break;

				case 'event':
					const event = message as Proto.Event;
					if (event.event === 'requestCompleted') {
						const seq = (event as Proto.RequestCompletedEvent).body.request_seq;
						const callback = this._callbacks.fetch(seq);
						if (callback) {
							this._tracer.traceRequestCompleted(this._serverId, 'requestCompleted', seq, callback);
							callback.onSuccess(undefined);
						}
					} else {
						this._tracer.traceEvent(this._serverId, event);
						this._onEvent.fire(event);
					}
					break;

				default:
					throw new Error(`Unknown message type ${message.type} received`);
			}
		} finally {
			this.sendNextRequests();
		}
	}

	private tryCancelRequest(seq: number, command: string): boolean {
		try {
			if (this._requestQueue.tryDeletePendingRequest(seq)) {
				this.logTrace(`Canceled request with sequence number ${seq}`);
				return true;
			}

			if (this._requestCanceller.tryCancelOngoingRequest(seq)) {
				return true;
			}

			this.logTrace(`Tried to cancel request with sequence number ${seq}. But request got already delivered.`);
			return false;
		} finally {
			const callback = this.fetchCallback(seq);
			if (callback) {
				callback.onSuccess(new ServerResponse.Cancelled(`Cancelled request ${seq} - ${command}`));
			}
		}
	}

	private dispatchResponse(response: Proto.Response) {
		const callback = this.fetchCallback(response.request_seq);
		if (!callback) {
			return;
		}

		this._tracer.traceResponse(this._serverId, response, callback);
		if (response.success) {
			callback.onSuccess(response);
		} else if (response.message === 'No content available.') {
			// Special case where response itself is successful but there is not any data to return.
			callback.onSuccess(ServerResponse.NoContent);
		} else {
			callback.onError(TypeScriptServerError.create(this._serverId, this._version, response));
		}
	}

	public executeImpl(command: keyof TypeScriptRequests, args: any, executeInfo: { isAsync: boolean, token?: vscode.CancellationToken, expectsResult: false, lowPriority?: boolean, executionTarget?: ExecutionTarget }): undefined;
	public executeImpl(command: keyof TypeScriptRequests, args: any, executeInfo: { isAsync: boolean, token?: vscode.CancellationToken, expectsResult: boolean, lowPriority?: boolean, executionTarget?: ExecutionTarget }): Promise<ServerResponse.Response<Proto.Response>>;
	public executeImpl(command: keyof TypeScriptRequests, args: any, executeInfo: { isAsync: boolean, token?: vscode.CancellationToken, expectsResult: boolean, lowPriority?: boolean, executionTarget?: ExecutionTarget }): Promise<ServerResponse.Response<Proto.Response>> | undefined {
		const request = this._requestQueue.createRequest(command, args);
		const requestInfo: RequestItem = {
			request,
			expectsResponse: executeInfo.expectsResult,
			isAsync: executeInfo.isAsync,
			queueingType: ProcessBasedTsServer.getQueueingType(command, executeInfo.lowPriority)
		};
		let result: Promise<ServerResponse.Response<Proto.Response>> | undefined;
		if (executeInfo.expectsResult) {
			result = new Promise<ServerResponse.Response<Proto.Response>>((resolve, reject) => {
				this._callbacks.add(request.seq, { onSuccess: resolve as () => ServerResponse.Response<Proto.Response> | undefined, onError: reject, queuingStartTime: Date.now(), isAsync: executeInfo.isAsync }, executeInfo.isAsync);

				if (executeInfo.token) {
					executeInfo.token.onCancellationRequested(() => {
						this.tryCancelRequest(request.seq, command);
					});
				}
			}).catch((err: Error) => {
				if (err instanceof TypeScriptServerError) {
					if (!executeInfo.token || !executeInfo.token.isCancellationRequested) {
						/* __GDPR__
							"languageServiceErrorResponse" : {
								"${include}": [
									"${TypeScriptCommonProperties}",
									"${TypeScriptRequestErrorProperties}"
								]
							}
						*/
						this._telemetryReporter.logTelemetry('languageServiceErrorResponse', err.telemetry);
					}
				}

				throw err;
			});
		}

		this._requestQueue.enqueue(requestInfo);
		this.sendNextRequests();

		return result;
	}

	private sendNextRequests(): void {
		while (this._pendingResponses.size === 0 && this._requestQueue.length > 0) {
			const item = this._requestQueue.dequeue();
			if (item) {
				this.sendRequest(item);
			}
		}
	}

	private sendRequest(requestItem: RequestItem): void {
		const serverRequest = requestItem.request;
		this._tracer.traceRequest(this._serverId, serverRequest, requestItem.expectsResponse, this._requestQueue.length);

		if (requestItem.expectsResponse && !requestItem.isAsync) {
			this._pendingResponses.add(requestItem.request.seq);
		}

		try {
			this.write(serverRequest);
		} catch (err) {
			const callback = this.fetchCallback(serverRequest.seq);
			if (callback) {
				callback.onError(err);
			}
		}
	}

	private fetchCallback(seq: number) {
		const callback = this._callbacks.fetch(seq);
		if (!callback) {
			return undefined;
		}

		this._pendingResponses.delete(seq);
		return callback;
	}

	private logTrace(message: string) {
		this._tracer.logTrace(this._serverId, message);
	}

	private static readonly fenceCommands = new Set(['change', 'close', 'open', 'updateOpen']);

	private static getQueueingType(
		command: string,
		lowPriority?: boolean
	): RequestQueueingType {
		if (ProcessBasedTsServer.fenceCommands.has(command)) {
			return RequestQueueingType.Fence;
		}
		return lowPriority ? RequestQueueingType.LowPriority : RequestQueueingType.Normal;
	}
}


interface ExecuteInfo {
	readonly isAsync: boolean;
	readonly token?: vscode.CancellationToken;
	readonly expectsResult: boolean;
	readonly lowPriority?: boolean;
	readonly executionTarget?: ExecutionTarget;
}

class RequestRouter {

	private static readonly sharedCommands = new Set<keyof TypeScriptRequests>([
		'change',
		'close',
		'open',
		'updateOpen',
		'configure',
	]);

	constructor(
		private readonly servers: ReadonlyArray<{
			readonly server: ITypeScriptServer;
			canRun?(command: keyof TypeScriptRequests, executeInfo: ExecuteInfo): void;
		}>,
		private readonly delegate: TsServerDelegate,
	) { }

	public execute(command: keyof TypeScriptRequests, args: any, executeInfo: ExecuteInfo): Promise<ServerResponse.Response<Proto.Response>> | undefined {
		if (RequestRouter.sharedCommands.has(command) && typeof executeInfo.executionTarget === 'undefined') {
			// Dispatch shared commands to all servers but only return from first one

			const requestStates: RequestState.State[] = this.servers.map(() => RequestState.Unresolved);

			// Also make sure we never cancel requests to just one server
			let token: vscode.CancellationToken | undefined = undefined;
			if (executeInfo.token) {
				const source = new vscode.CancellationTokenSource();
				executeInfo.token.onCancellationRequested(() => {
					if (requestStates.some(state => state === RequestState.Resolved)) {
						// Don't cancel.
						// One of the servers completed this request so we don't want to leave the other
						// in a different state.
						return;
					}
					source.cancel();
				});
				token = source.token;
			}

			let firstRequest: Promise<ServerResponse.Response<Proto.Response>> | undefined;

			for (let serverIndex = 0; serverIndex < this.servers.length; ++serverIndex) {
				const server = this.servers[serverIndex].server;

				const request = server.executeImpl(command, args, { ...executeInfo, token }) as Promise<ServerResponse.Response<Proto.Response>> | undefined;
				if (serverIndex === 0) {
					firstRequest = request;
				}
				if (request) {
					request
						.then(result => {
							requestStates[serverIndex] = RequestState.Resolved;
							const erroredRequest = requestStates.find(state => state.type === RequestState.Type.Errored) as RequestState.Errored | undefined;
							if (erroredRequest) {
								// We've gone out of sync
								this.delegate.onFatalError(command, erroredRequest.err);
							}
							return result;
						}, err => {
							requestStates[serverIndex] = new RequestState.Errored(err);
							if (requestStates.some(state => state === RequestState.Resolved)) {
								// We've gone out of sync
								this.delegate.onFatalError(command, err);
							}
							throw err;
						});
				}
			}

			return firstRequest;
		}

		for (const { canRun, server } of this.servers) {
			if (!canRun || canRun(command, executeInfo)) {
				return server.executeImpl(command, args, executeInfo);
			}
		}

		throw new Error(`Could not find server for command: '${command}'`);
	}
}

export class GetErrRoutingTsServer extends Disposable implements ITypeScriptServer {

	private static readonly diagnosticEvents = new Set<string>([
		EventName.configFileDiag,
		EventName.syntaxDiag,
		EventName.semanticDiag,
		EventName.suggestionDiag
	]);

	private readonly getErrServer: ITypeScriptServer;
	private readonly mainServer: ITypeScriptServer;
	private readonly router: RequestRouter;

	public constructor(
		servers: { getErr: ITypeScriptServer, primary: ITypeScriptServer },
		delegate: TsServerDelegate,
	) {
		super();

		this.getErrServer = servers.getErr;
		this.mainServer = servers.primary;

		this.router = new RequestRouter(
			[
				{ server: this.getErrServer, canRun: (command) => ['geterr', 'geterrForProject'].includes(command) },
				{ server: this.mainServer, canRun: undefined /* gets all other commands */ }
			],
			delegate);

		this._register(this.getErrServer.onEvent(e => {
			if (GetErrRoutingTsServer.diagnosticEvents.has(e.event)) {
				this._onEvent.fire(e);
			}
			// Ignore all other events
		}));
		this._register(this.mainServer.onEvent(e => {
			if (!GetErrRoutingTsServer.diagnosticEvents.has(e.event)) {
				this._onEvent.fire(e);
			}
			// Ignore all other events
		}));

		this._register(this.getErrServer.onError(e => this._onError.fire(e)));
		this._register(this.mainServer.onError(e => this._onError.fire(e)));

		this._register(this.mainServer.onExit(e => {
			this._onExit.fire(e);
			this.getErrServer.kill();
		}));
	}

	private readonly _onEvent = this._register(new vscode.EventEmitter<Proto.Event>());
	public readonly onEvent = this._onEvent.event;

	private readonly _onExit = this._register(new vscode.EventEmitter<any>());
	public readonly onExit = this._onExit.event;

	private readonly _onError = this._register(new vscode.EventEmitter<any>());
	public readonly onError = this._onError.event;

	public get tsServerLogFile() { return this.mainServer.tsServerLogFile; }

	public kill(): void {
		this.getErrServer.kill();
		this.mainServer.kill();
	}

	public executeImpl(command: keyof TypeScriptRequests, args: any, executeInfo: { isAsync: boolean, token?: vscode.CancellationToken, expectsResult: false, lowPriority?: boolean, executionTarget?: ExecutionTarget }): undefined;
	public executeImpl(command: keyof TypeScriptRequests, args: any, executeInfo: { isAsync: boolean, token?: vscode.CancellationToken, expectsResult: boolean, lowPriority?: boolean, executionTarget?: ExecutionTarget }): Promise<ServerResponse.Response<Proto.Response>>;
	public executeImpl(command: keyof TypeScriptRequests, args: any, executeInfo: { isAsync: boolean, token?: vscode.CancellationToken, expectsResult: boolean, lowPriority?: boolean, executionTarget?: ExecutionTarget }): Promise<ServerResponse.Response<Proto.Response>> | undefined {
		return this.router.execute(command, args, executeInfo);
	}
}


export class SyntaxRoutingTsServer extends Disposable implements ITypeScriptServer {

	/**
	 * Commands that should always be run on the syntax server.
	 */
	private static readonly syntaxAlwaysCommands = new Set<keyof TypeScriptRequests>([
		'navtree',
		'getOutliningSpans',
		'jsxClosingTag',
		'selectionRange',
		'format',
		'formatonkey',
		'docCommentTemplate',
	]);

	/**
	 * Commands that should always be run on the semantic server.
	 */
	private static readonly semanticCommands = new Set<keyof TypeScriptRequests>([
		'geterr',
		'geterrForProject',
		'projectInfo',
		'configurePlugin',
	]);

	/**
	 * Commands that can be run on the syntax server but would benefit from being upgraded to the semantic server.
	 */
	private static readonly syntaxAllowedCommands = new Set<keyof TypeScriptRequests>([
		'completions',
		'completionEntryDetails',
		'completionInfo',
		'definition',
		'definitionAndBoundSpan',
		'documentHighlights',
		'implementation',
		'navto',
		'quickinfo',
		'references',
		'rename',
		'signatureHelp',
	]);

	private readonly syntaxServer: ITypeScriptServer;
	private readonly semanticServer: ITypeScriptServer;
	private readonly router: RequestRouter;

	private _projectLoading = true;

	public constructor(
		servers: { syntax: ITypeScriptServer, semantic: ITypeScriptServer },
		delegate: TsServerDelegate,
		enableDynamicRouting: boolean,
	) {
		super();

		this.syntaxServer = servers.syntax;
		this.semanticServer = servers.semantic;

		this.router = new RequestRouter(
			[
				{
					server: this.syntaxServer,
					canRun: (command, execInfo) => {
						switch (execInfo.executionTarget) {
							case ExecutionTarget.Semantic: return false;
							case ExecutionTarget.Syntax: return true;
						}

						if (SyntaxRoutingTsServer.syntaxAlwaysCommands.has(command)) {
							return true;
						}
						if (SyntaxRoutingTsServer.semanticCommands.has(command)) {
							return false;
						}
						if (enableDynamicRouting && this.projectLoading && SyntaxRoutingTsServer.syntaxAllowedCommands.has(command)) {
							return true;
						}
						return false;
					}
				}, {
					server: this.semanticServer,
					canRun: undefined /* gets all other commands */
				}
			],
			delegate);

		this._register(this.syntaxServer.onEvent(e => {
			return this._onEvent.fire(e);
		}));

		this._register(this.semanticServer.onEvent(e => {
			switch (e.event) {
				case EventName.projectLoadingStart:
					this._projectLoading = true;
					break;

				case EventName.projectLoadingFinish:
				case EventName.semanticDiag:
				case EventName.syntaxDiag:
				case EventName.suggestionDiag:
				case EventName.configFileDiag:
					this._projectLoading = false;
					break;
			}
			return this._onEvent.fire(e);
		}));

		this._register(this.semanticServer.onExit(e => {
			this._onExit.fire(e);
			this.syntaxServer.kill();
		}));

		this._register(this.semanticServer.onError(e => this._onError.fire(e)));
	}

	private get projectLoading() { return this._projectLoading; }

	private readonly _onEvent = this._register(new vscode.EventEmitter<Proto.Event>());
	public readonly onEvent = this._onEvent.event;

	private readonly _onExit = this._register(new vscode.EventEmitter<any>());
	public readonly onExit = this._onExit.event;

	private readonly _onError = this._register(new vscode.EventEmitter<any>());
	public readonly onError = this._onError.event;

	public get tsServerLogFile() { return this.semanticServer.tsServerLogFile; }

	public kill(): void {
		this.syntaxServer.kill();
		this.semanticServer.kill();
	}

	public executeImpl(command: keyof TypeScriptRequests, args: any, executeInfo: { isAsync: boolean, token?: vscode.CancellationToken, expectsResult: false, lowPriority?: boolean, executionTarget?: ExecutionTarget }): undefined;
	public executeImpl(command: keyof TypeScriptRequests, args: any, executeInfo: { isAsync: boolean, token?: vscode.CancellationToken, expectsResult: boolean, lowPriority?: boolean, executionTarget?: ExecutionTarget }): Promise<ServerResponse.Response<Proto.Response>>;
	public executeImpl(command: keyof TypeScriptRequests, args: any, executeInfo: { isAsync: boolean, token?: vscode.CancellationToken, expectsResult: boolean, lowPriority?: boolean, executionTarget?: ExecutionTarget }): Promise<ServerResponse.Response<Proto.Response>> | undefined {
		return this.router.execute(command, args, executeInfo);
	}
}

namespace RequestState {
	export const enum Type { Unresolved, Resolved, Errored }

	export const Unresolved = { type: Type.Unresolved } as const;

	export const Resolved = { type: Type.Resolved } as const;

	export class Errored {
		readonly type = Type.Errored;

		constructor(
			public readonly err: Error
		) { }
	}

	export type State = typeof Unresolved | typeof Resolved | Errored;
}