/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

'use strict';

const wskprops = require('./wskprops');
const OpenWhiskInvoker = require('./invoker');
const AgentMgr = require('./agentmgr');
const Watcher = require('./watcher');
const openwhisk = require('openwhisk');
const { spawnSync } = require('child_process');
const sleep = require('util').promisify(setTimeout);

/**
 * Central component of wskdebug.
 */
class Debugger {
    constructor(argv) {
        this.argv = argv;
        this.actionName = argv.action;

        this.wskProps = wskprops.get();
        if (argv.ignoreCerts) {
            this.wskProps.ignore_certs = true;
        }
    }

    async start() {
        await this.setupWsk();

        this.agentMgr = new AgentMgr(this.argv, this.wsk, this.actionName);
        this.watcher = new Watcher(this.argv, this.wsk);

        // quick fail for missing requirements such as docker not running
        await OpenWhiskInvoker.checkIfAvailable();

        console.info(`Starting debugger for /${this.wskProps.namespace}/${this.actionName}`);

        // get the action
        const { action, agentAlreadyInstalled } = await this.agentMgr.readAction();

        // local debug container
        this.invoker = new OpenWhiskInvoker(this.actionName, action, this.argv, this.wskProps, this.wsk);

        try {
            // run build initially (would be required by starting container)
            if (this.argv.onBuild) {
                console.info("=> Build:", this.argv.onBuild);
                spawnSync(this.argv.onBuild, {shell: true, stdio: "inherit"});
            }

            // start container - get it up fast for VSCode to connect within its 10 seconds timeout
            await this.invoker.startContainer();

            // get code and /init local container
            if (this.argv.verbose) {
                console.log(`Fetching action code from OpenWhisk: ${this.actionName}`);
            }
            const actionWithCode = await this.wsk.actions.get(this.actionName);
            action.exec = actionWithCode.exec;
            await this.invoker.init(actionWithCode);

            // setup agent in openwhisk

            // user can switch between agents (ngrok or not), hence we need to restore
            // (better would be to track the agent + its version and avoid a restore, but that's TBD)
            if (agentAlreadyInstalled) {
                await this.agentMgr.restoreAction();
            }

            await this.agentMgr.installAgent(action, this.invoker);

            if (this.argv.onStart) {
                console.log("On start:", this.argv.onStart);
                spawnSync(this.argv.onStart, {shell: true, stdio: "inherit"});
            }

            // start source watching (live reload) if requested
            await this.watcher.start();

            console.log();
            console.info(`Action     : ${this.actionName}`);
            this.invoker.logInfo();
            if (this.argv.condition) {
                console.info(`Condition  : ${this.argv.condition}`);
            }
            console.log();
            console.info(`Ready, waiting for activations! Use CTRL+C to exit`);

            this.ready = true;

        } catch (e) {
            await this.shutdown();
            throw e;
        }
    }

    async run() {
        return this.runPromise = this._run();
    }

    async _run() {
        try {
            this.running = true;
            this.shuttingDown = false;

            // main blocking loop
            // abort if this.running is set to false
            // from here on, user can end debugger with ctrl+c
            while (this.running) {
                if (this.argv.ngrok) {
                    // agent: ngrok
                    // simply block, ngrokServer keeps running in background
                    await sleep(1000);

                } else {
                    // agent: concurrent
                    // agent: non-concurrent
                    // wait for activation, run it, complete, repeat
                    const activation = await this.agentMgr.waitForActivations();
                    if (!activation) {
                        return;
                    }

                    const id = activation.$activationId;
                    delete activation.$activationId;

                    const startTime = Date.now();

                    // run this activation on the local docker container
                    // which will block if the actual debugger hits a breakpoint
                    const result = await this.invoker.run(activation, id);

                    const duration = Date.now() - startTime;

                    // pass on the local result to the agent in openwhisk
                    if (!await this.agentMgr.completeActivation(id, result, duration)) {
                        return;
                    }
                }
            }
        } finally {
            await this.shutdown();
        }
    }

    // normal graceful stop() initiated by a client
    async stop() {
        this.running = false;
        if (this.agentMgr) {
            this.agentMgr.stop();
        }

        if (this.runPromise) {
            // wait for the main loop to gracefully end, which will call shutdown()
            await this.runPromise;
        } else {
            // someone called stop() without run()
            await this.shutdown();
        }
    }

    // fastest way to end, triggered by CTRL+C
    async kill() {
        this.running = false;
        if (this.agentMgr) {
            this.agentMgr.stop();
        }

        await this.shutdown();
    }

    async shutdown() {
        // avoid duplicate shutdown on CTRL+C
        if (this.shuttingDown) {
            return;
        }
        this.shuttingDown = true;

        // only log this if we started properly
        if (this.ready) {
            console.log();
            console.log();
            console.log("Shutting down...");
        }

        // need to shutdown everything even if some fail, hence tryCatch() for each

        if (this.agentMgr) {
            await this.tryCatch(this.agentMgr.shutdown());
        }
        if (this.invoker) {
            await this.tryCatch(this.invoker.stop());
        }
        if (this.watcher) {
            await this.tryCatch(this.watcher.stop());
        }

        // only log this if we started properly
        if (this.ready) {
            console.log(`Done`);
        }
        this.ready = false;
    }

    // ------------------------------------------------< openwhisk utils >------------------

    async setupWsk() {
        if (!this.wsk) {
            this.wsk = openwhisk(this.wskProps);
            if (this.wskProps.namespace === undefined) {
                // there is a strict 1-1 bijection between auth and namespace, hence auth is enough.
                // while the openwhisk() client does not care about the namespace being set,
                // some code here in wskdebug relies on it to be set correctly.
                const namespaces = await this.wsk.namespaces.list();
                if (!namespaces || namespaces.length < 1) {
                    console.error("Error: Unknown namespace. Please specify as NAMESPACE in .wskprops.");
                    process.exit(2);
                }
                if (namespaces.length > 1) {
                    console.error("Error: OpenWhisk reports access to more than one namespace. Please specify the namespace to use as NAMESPACE in .wskprops.", namespaces);
                    process.exit(2);
                }
                this.wskProps.namespace = namespaces[0];
            }
        }
    }

    // ------------------------------------------------< utils >-----------------

    async tryCatch(task, message="Error during shutdown:") {
        try {
            if (typeof task === "function") {
                task();
            } else {
                await task;
            }
        } catch (e) {
            console.log(e);
            if (this.argv.verbose) {
                console.error(message);
                console.error(e);
            } else {
                console.error(message, e.message);
            }
        }
    }

}

module.exports = Debugger;