// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for details.

import { IncomingMessage } from "http";
import {
    Connection,
    Server,
    WebSocketTransport,
    IProtocolCommand,
    IProtocolError,
    IProtocolSuccess,
} from "vscode-cdp-proxy";
import { CancellationToken, EventEmitter } from "vscode";
import { OutputChannelLogger } from "../extension/log/OutputChannelLogger";
import { LogLevel } from "../extension/log/LogHelper";
import { DebuggerEndpointHelper } from "./debuggerEndpointHelper";
import { BaseCDPMessageHandler } from "./CDPMessageHandlers/baseCDPMessageHandler";

export class ReactNativeCDPProxy {
    private readonly PROXY_LOG_TAGS = {
        DEBUGGER_COMMAND: "Command Debugger To Target",
        APPLICATION_COMMAND: "Command Target To Debugger",
        DEBUGGER_REPLY: "Reply From Debugger To Target",
        APPLICATION_REPLY: "Reply From Target To Debugger",
    };

    private server: Server | null = null;
    private hostAddress: string;
    private port: number;
    private debuggerTarget: Connection | null = null;
    private applicationTarget: Connection | null = null;
    private logger: OutputChannelLogger;
    private logLevel: LogLevel;
    private debuggerEndpointHelper: DebuggerEndpointHelper;
    private CDPMessageHandler!: BaseCDPMessageHandler;
    private applicationTargetPort: number = 0;
    private browserInspectUri: string;
    private cancellationToken: CancellationToken | undefined;
    private applicationTargetEventEmitter: EventEmitter<unknown> = new EventEmitter();
    private errorEventEmitter: EventEmitter<Error> = new EventEmitter();

    public readonly onError = this.errorEventEmitter.event;
    public readonly onApplicationTargetConnectionClosed = this.applicationTargetEventEmitter.event;

    constructor(hostAddress: string, port: number, logLevel: LogLevel = LogLevel.None) {
        this.port = port;
        this.hostAddress = hostAddress;
        this.logger = OutputChannelLogger.getChannel(
            "React Native Chrome Proxy",
            process.env.REACT_NATIVE_TOOLS_LAZY_LOGS !== "false",
            false,
            true,
        );
        this.logLevel = logLevel;
        this.browserInspectUri = "";
        this.debuggerEndpointHelper = new DebuggerEndpointHelper();
    }

    public async initializeServer(
        CDPMessageHandler: BaseCDPMessageHandler,
        logLevel: LogLevel,
        cancellationToken?: CancellationToken,
    ): Promise<void> {
        this.logLevel = logLevel;
        this.CDPMessageHandler = CDPMessageHandler;
        this.cancellationToken = cancellationToken;

        this.server = await Server.create({ port: this.port, host: this.hostAddress });
        this.server.onConnection(this.onConnectionHandler.bind(this));
    }

    public async stopServer(): Promise<void> {
        if (this.server) {
            this.server.dispose();
            this.server = null;
        }

        if (this.applicationTarget) {
            await this.applicationTarget.close();
            this.applicationTarget = null;
        }

        this.browserInspectUri = "";
        this.cancellationToken = undefined;
    }

    public setBrowserInspectUri(browserInspectUri: string): void {
        this.browserInspectUri = browserInspectUri;
    }

    public setApplicationTargetPort(applicationTargetPort: number): void {
        this.applicationTargetPort = applicationTargetPort;
    }

    // eslint-disable-next-line @typescript-eslint/no-unused-vars
    private async onConnectionHandler([debuggerTarget, request]: [
        Connection,
        IncomingMessage,
    ]): Promise<void> {
        // Only allow connections without an Origin header (i.e., from vscode-js-debug's
        // raw WebSocket client). Browser-initiated WebSocket connections always include
        // an Origin header and should be rejected.
        if (request.headers.origin) {
            await debuggerTarget.close();
            return;
        }

        this.debuggerTarget = debuggerTarget;

        this.debuggerTarget.pause(); // don't listen for events until the target is ready

        if (!this.browserInspectUri) {
            if (this.cancellationToken) {
                this.browserInspectUri = await this.debuggerEndpointHelper.retryGetWSEndpoint(
                    `http://localhost:${this.applicationTargetPort}`,
                    90,
                    this.cancellationToken,
                );
            } else {
                this.browserInspectUri = await this.debuggerEndpointHelper.getWSEndpoint(
                    `http://localhost:${this.applicationTargetPort}`,
                );
            }
        }

        this.applicationTarget = new Connection(
            await WebSocketTransport.create(this.browserInspectUri),
        );

        this.applicationTarget.onError(this.onApplicationTargetError.bind(this));
        this.debuggerTarget.onError(this.onDebuggerTargetError.bind(this));

        this.applicationTarget.onCommand(this.handleApplicationTargetCommand.bind(this));
        this.debuggerTarget.onCommand(this.handleDebuggerTargetCommand.bind(this));

        this.applicationTarget.onReply(this.handleApplicationTargetReply.bind(this));
        this.debuggerTarget.onReply(this.handleDebuggerTargetReply.bind(this));

        this.applicationTarget.onEnd(this.onApplicationTargetClosed.bind(this));
        this.debuggerTarget.onEnd(this.onDebuggerTargetClosed.bind(this));

        this.CDPMessageHandler?.setApplicationTarget(this.applicationTarget);
        this.CDPMessageHandler?.setDebuggerTarget(this.debuggerTarget);

        // dequeue any messages we got in the meantime
        this.debuggerTarget.unpause();
    }

    private handleDebuggerTargetCommand(event: IProtocolCommand) {
        this.logger.logWithCustomTag(
            this.PROXY_LOG_TAGS.DEBUGGER_COMMAND,
            JSON.stringify(event, null, 2),
            this.logLevel,
        );
        const processedMessage = this.CDPMessageHandler.processDebuggerCDPMessage(event);

        if (processedMessage.sendBack) {
            this.debuggerTarget?.send(processedMessage.event);
        } else {
            this.applicationTarget?.send(processedMessage.event);
        }
    }

    private handleApplicationTargetCommand(event: IProtocolCommand) {
        this.logger.logWithCustomTag(
            this.PROXY_LOG_TAGS.APPLICATION_COMMAND,
            JSON.stringify(event, null, 2),
            this.logLevel,
        );
        const processedMessage = this.CDPMessageHandler.processApplicationCDPMessage(event);

        if (processedMessage.sendBack) {
            this.applicationTarget?.send(processedMessage.event);
        } else {
            this.debuggerTarget?.send(processedMessage.event);
        }
    }

    private handleDebuggerTargetReply(event: IProtocolError | IProtocolSuccess) {
        this.logger.logWithCustomTag(
            this.PROXY_LOG_TAGS.DEBUGGER_REPLY,
            JSON.stringify(event, null, 2),
            this.logLevel,
        );
        const processedMessage = this.CDPMessageHandler.processDebuggerCDPMessage(event);

        if (processedMessage.sendBack) {
            this.debuggerTarget?.send(processedMessage.event);
        } else {
            this.applicationTarget?.send(processedMessage.event);
        }
    }

    private handleApplicationTargetReply(event: IProtocolError | IProtocolSuccess) {
        this.logger.logWithCustomTag(
            this.PROXY_LOG_TAGS.APPLICATION_REPLY,
            JSON.stringify(event, null, 2),
            this.logLevel,
        );
        const processedMessage = this.CDPMessageHandler.processApplicationCDPMessage(event);

        if (processedMessage.sendBack) {
            this.applicationTarget?.send(processedMessage.event);
        } else {
            this.debuggerTarget?.send(processedMessage.event);
        }
    }

    private onDebuggerTargetError(err: Error) {
        this.logger.error("Error on debugger transport", err);
    }

    private onApplicationTargetError(err: Error) {
        this.logger.error("Error on application transport", err);
    }

    private async onApplicationTargetClosed() {
        this.applicationTarget = null;
        this.applicationTargetEventEmitter.fire({});
    }

    private async onDebuggerTargetClosed() {
        this.browserInspectUri = "";
        this.CDPMessageHandler.processDebuggerCDPMessage({ method: "close" });
        this.debuggerTarget = null;
    }
}