'use strict';

exports = module.exports = {
    getSystem,
    getSystemStream,

    getContainer,
    getContainerStream,

    sendToGraphite
};

const apps = require('./apps.js'),
    assert = require('assert'),
    BoxError = require('./boxerror.js'),
    constants = require('./constants.js'),
    debug = require('debug')('box:metrics'),
    docker = require('./docker.js'),
    fs = require('fs'),
    net = require('net'),
    os = require('os'),
    path = require('path'),
    { Readable } = require('stream'),
    safe = require('safetydance'),
    services = require('./services.js'),
    superagent = require('./superagent.js');

function translateContainerStatsSync(stats) {
    assert.strictEqual(typeof stats, 'object');

    const networkRead = stats.networks ? stats.networks.eth0.rx_bytes : 0; // in host mode (turn), networks is missing
    const networkWrite = stats.networks ? stats.networks.eth0.tx_bytes : 0; // in host mode (turn), networks is missing

    const memoryUsed = stats.memory_stats.usage;
    const memoryMax = stats.memory_stats.limit;

    const blkioStats = stats.blkio_stats.io_service_bytes_recursive;
    const blockRead = blkioStats.filter(entry => entry.op === 'read').reduce((sum, entry) => sum + entry.value, 0);
    const blockWrite = blkioStats.filter(entry => entry.op === 'write').reduce((sum, entry) => sum + entry.value, 0);

    const cpuUsageMsecs = stats.cpu_stats.cpu_usage.total_usage / 1e6; // convert from nano to msecs (to match system metrics)
    const systemUsageMsecs = stats.cpu_stats.system_cpu_usage / 1e6;

    return { ts: new Date(stats.read), networkRead, networkWrite, blockRead, blockWrite, memoryUsed, memoryMax, cpuUsageMsecs, systemUsageMsecs };
}

async function readContainerMetrics() {
    const allAddons = [ 'turn', 'mail', 'mongodb', 'mysql', 'postgresql' ];

    const containerNames = allAddons;
    for (const app of await apps.list()) {
        if (app.containerId) containerNames.push(app.containerId); // containerId can be null if app is installing
        if (app.manifest.addons?.redis && app.enableRedis) containerNames.push(`redis-${app.id}`);
    }

    const metrics = {};
    for (const containerName of containerNames) {
        const [error, stats] = await safe(docker.getStats(containerName, { stream: false }));
        if (error || Object.keys(stats.memory_stats).length === 0) continue; // the container is missing or stopped. better not to inspect and check State since a race is possible

        metrics[containerName] = translateContainerStatsSync(stats);
    }

    return metrics;
}

async function readMemoryMetrics() {
    const output = await fs.promises.readFile('/proc/meminfo', { encoding: 'utf8' });

    const totalMemoryMatch = output.match(/^MemTotal:\s+(\d+)/m);
    const freeMemoryMatch = output.match(/^MemFree:\s+(\d+)/m);
    const buffersMatch = output.match(/^Buffers:\s+(\d+)/m);
    const cachedMatch = output.match(/^Cached:\s+(\d+)/m);

    if (!totalMemoryMatch || !freeMemoryMatch || !buffersMatch || !cachedMatch) throw new BoxError(BoxError.EXTERNAL_ERROR, 'Could not find memory used');

    const memoryUsed = parseInt(totalMemoryMatch[1]) * 1024 - parseInt(freeMemoryMatch[1]) * 1024 - parseInt(buffersMatch[1]) * 1024 - parseInt(cachedMatch[1]) * 1024;

    const swapTotalMatch = output.match(/^SwapTotal:\s+(\d+)/m);
    const swapFreeMatch = output.match(/^SwapFree:\s+(\d+)/m);

    if (!swapTotalMatch || !swapFreeMatch) throw new BoxError(BoxError.EXTERNAL_ERROR, 'Could not find swap used');

    const swapUsed = parseInt(swapTotalMatch[1]) * 1024 - parseInt(swapFreeMatch[1]) * 1024;

    return {
        memoryUsed,
        swapUsed
    };
}

async function readCpuMetrics() {
    const cpus = os.cpus();
    const userMsecs = cpus.map(c => c.times.user).reduce((p, c) => p+c);
    const sysMsecs = cpus.map(c => c.times.sys).reduce((p, c) => p+c);

    return { userMsecs, sysMsecs }; // these values are the times spent since system start
}

async function readDiskMetrics() {
    const mounts = await fs.promises.readFile('/proc/mounts', { encoding: 'utf8' });
    const rootLine = mounts.split('\n').find(line => line.split(' ')[1] === '/');
    if (!rootLine) throw new BoxError(BoxError.EXTERNAL_ERROR, 'Root mount not found');

    const devicePath = rootLine.split(' ')[0]; // e.g., "/dev/sda1"
    const base = path.basename(devicePath); // remove /dev/
    const match = base.match(/^(.*?)(p?[0-9]+)?$/);
    const blockDevice = match ? match[1] : base;
    if (!blockDevice) throw new BoxError(BoxError.EXTERNAL_ERROR, 'Could not find root block device name');


    const diskstats = await fs.promises.readFile('/proc/diskstats', { encoding: 'utf8' });
    const statsLine = diskstats.split('\n').find(l => l.includes(` ${blockDevice} `));
    if (!blockDevice) throw new BoxError(BoxError.EXTERNAL_ERROR, 'Could not get disk stats');

    const parts = statsLine.trim().split(/\s+/);
    const sectorsRead = parseInt(parts[5], 10);   // field 6 . one sectiro is 512 bytes
    const sectorsWrite = parseInt(parts[9], 10); // field 10
    const blockRead = sectorsRead * 512;
    const blockWrite = sectorsWrite * 512;

    return { blockRead, blockWrite };
}

async function readNetworkMetrics() {
    const contents = await fs.promises.readFile('/proc/net/route', { encoding: 'utf8' });
    const lines = contents.trim().split('\n').slice(1); // skip header

    let defaultIface = null;
    for (const line of lines) {
        const [iface, destination] = line.split(/\s+/);
        if (destination === '00000000') {
            defaultIface = iface; // default route
            break;
        }
    }
    if (!defaultIface) throw new BoxError(BoxError.EXTERNAL_ERROR, 'Could not detect default interface');

    const [rx, tx] = await Promise.all([
        fs.promises.readFile(`/sys/class/net/${defaultIface}/statistics/rx_bytes`, { encoding: 'utf8' }),
        fs.promises.readFile(`/sys/class/net/${defaultIface}/statistics/tx_bytes`, { encoding: 'utf8' })
    ]);

    return {
        networkRead: parseInt(rx.trim(), 10),
        networkWrite: parseInt(tx.trim(), 10)
    };
}

async function readSystemMetrics() {
    const memoryMetrics = await readMemoryMetrics();
    const cpuMetrics = await readCpuMetrics();
    const diskMetrics = await readDiskMetrics();
    const networkMetrics = await readNetworkMetrics();

    // { memoryUsed, swapUsed, userMsecs, sysMsecs, blockRead, blockWrite, networkRead, networkWrite }
    return { ...memoryMetrics, ...cpuMetrics, ...diskMetrics, ...networkMetrics };
}

async function sendToGraphite() {
    // debug('sendStatsToGraphite: collecting stats');

    const result = await readSystemMetrics();

    const graphiteMetrics = [
        { path: `cloudron.system.memory-used`, value: result.memoryUsed },
        { path: `cloudron.system.swap-used`, value: result.swapUsed },
        { path: `cloudron.system.cpu-user`, value: result.userMsecs },
        { path: `cloudron.system.cpu-sys`, value: result.sysMsecs  },
        { path: `cloudron.system.blockio-read`, value: result.blockRead },
        { path: `cloudron.system.blockio-write`, value: result.blockWrite },
        { path: `cloudron.system.network-read`, value: result.networkRead },
        { path: `cloudron.system.network-write`, value: result.networkWrite }
    ];

    const dockerMetrics = await readContainerMetrics();
    for (const [name, value] of Object.entries(dockerMetrics)) {
        graphiteMetrics.push(
            { path: `cloudron.container-${name}.network-read`, value: value.networkRead },
            { path: `cloudron.container-${name}.network-write`, value: value.networkWrite },
            { path: `cloudron.container-${name}.blockio-read`, value: value.blockRead },
            { path: `cloudron.container-${name}.blockio-write`, value: value.blockWrite },
            { path: `cloudron.container-${name}.memory-used`, value: value.memoryUsed },
            { path: `cloudron.container-${name}.memory-max`, value: value.memoryMax },
            { path: `cloudron.container-${name}.cpu-usage`, value: value.cpuUsageMsecs },
        );
    }

    return new Promise((resolve) => {
        const client = new net.Socket();
        client.connect(constants.GRAPHITE_PORT, '127.0.0.1', () => {
            debug('connected to graphite');

            const now = Math.floor(Date.now() / 1000);

            for (const metric of graphiteMetrics) {
                client.write(`${metric.path} ${metric.value} ${now}\n`);
            }
            client.end();
        });

        client.on('error', (error) => {
            debug(error);
            resolve();
        });

        client.on('end', () => {
            debug('sent to graphite');
            resolve();
        });
    });
}

// for testing locally: curl 'http://${graphite-ip}:8000/graphite-web/render?format=json&from=-1min&target=absolute(collectd.localhost.du-docker.capacity-usage)'
// the datapoint is (value, timestamp) https://graphite.readthedocs.io/en/latest/
async function getGraphiteUrl() {
    const [error, result] = await safe(docker.inspect('graphite'));
    if (error && error.reason === BoxError.NOT_FOUND) return { status: exports.SERVICE_STATUS_STOPPED };
    if (error) throw error;

    const ip = safe.query(result, 'NetworkSettings.Networks.cloudron.IPAddress', null);
    if (!ip) throw new BoxError(BoxError.INACTIVE, 'Error getting IP of graphite service');

    return `http://${ip}:8000/graphite-web/render`;
}

async function getContainer(name, options) {
    assert.strictEqual(typeof name, 'string');
    assert.strictEqual(typeof options, 'object');

    const { fromSecs, intervalSecs, noNullPoints } = options;

    const graphiteUrl = await getGraphiteUrl();

    const targets = [
        // perSecond is nonNegativeDerivative over time . this value is the cpu usage in msecs .
        // (cpu usage msecs) / (cpus * 1000) is the percent but over all cpus. times 100 is the percent.
        // but the y-scale is cpus times 100. so, we only need to scale by 0.1
        `scale(perSecond(cloudron.container-${name}.cpu-usage),0.1)`,
        `summarize(cloudron.container-${name}.memory-used, "${intervalSecs}s", "avg")`,

        // get the rate in interval window
        `summarize(perSecond(cloudron.container-${name}.blockio-read), "${intervalSecs}s", "avg")`,
        `summarize(perSecond(cloudron.container-${name}.blockio-write), "${intervalSecs}s", "avg")`,
        `summarize(perSecond(cloudron.container-${name}.network-read), "${intervalSecs}s", "avg")`,
        `summarize(perSecond(cloudron.container-${name}.network-write), "${intervalSecs}s", "avg")`,

        // just get the max in interval window for absolute numbers
        `summarize(cloudron.container-${name}.blockio-read, "${intervalSecs}s", "max")`,
        `summarize(cloudron.container-${name}.blockio-write, "${intervalSecs}s", "max")`,
        `summarize(cloudron.container-${name}.network-read, "${intervalSecs}s", "max")`,
        `summarize(cloudron.container-${name}.network-write, "${intervalSecs}s", "max")`,
    ];

    const results = [];

    for (const target of targets) {
        const query = {
            target: target,
            format: 'json',
            from: `-${fromSecs}s`,
            until: 'now',
            noNullPoints: !!noNullPoints
        };

        const [error, response] = await safe(superagent.get(graphiteUrl).query(query).timeout(30 * 1000).ok(() => true));
        if (error) throw new BoxError(BoxError.NETWORK_ERROR, error);
        if (response.status !== 200) throw new BoxError(BoxError.EXTERNAL_ERROR, `Unknown error with ${target}: ${response.status} ${response.text}`);

        results.push(response.body[0] && response.body[0].datapoints ? response.body[0].datapoints : []);
    }

    // results are datapoints[[value, ts], [value, ts], ...];
    return {
        cpu: results[0],
        memory: results[1],
        blockReadRate: results[2],
        blockWriteRate: results[3],
        networkReadRate: results[4],
        networkWriteRate: results[5],
        blockReadTotal: results[6][0] && results[6][0][0] ? results[6][0][0] : 0,
        blockWriteTotal: results[7][0] && results[7][0][0] ? results[7][0][0] : 0,
        networkReadTotal: results[8][0] && results[8][0][0] ? results[8][0][0] : 0,
        networkWriteTotal: results[9][0] && results[9][0][0] ? results[9][0][0] : 0,
    };
}

async function readSystemFromGraphite(options) {
    assert.strictEqual(typeof options, 'object');

    const { fromSecs, intervalSecs, noNullPoints } = options;

    const graphiteUrl = await getGraphiteUrl();

    // example: curl 'http://172.18.30.5:8000/graphite-web/render?target=cloudron.system.cpu-user&target=cloudron.system.cpu-sys&format=json&from=-1min&until=now&noNullPoints=false' | python3 -m json.tool
    const targets = [
        // perSecond is nonNegativeDerivative over time . this value is the cpu usage in msecs .
        // (cpu usage msecs) / (cpus * 1000) is the percent but over all cpus. times 100 is the percent.
        // but the y-scale is cpus times 100. so, we only need to scale by 0.1
        `scale(perSecond(sumSeries(cloudron.system.cpu-user,cloudron.system.cpu-sys)),0.1)`,
        `summarize(cloudron.system.memory-used, "${intervalSecs}s", "avg")`,
        `summarize(cloudron.system.swap-used, "${intervalSecs}s", "avg")`,

        // get the rate in interval window
        `summarize(perSecond(cloudron.system.blockio-read), "${intervalSecs}s", "avg")`,
        `summarize(perSecond(cloudron.system.blockio-write), "${intervalSecs}s", "avg")`,
        `summarize(perSecond(cloudron.system.network-read), "${intervalSecs}s", "avg")`,
        `summarize(perSecond(cloudron.system.network-write), "${intervalSecs}s", "avg")`,

        // just get the max in interval window for absolute numbers
        `summarize(cloudron.system.blockio-read, "${intervalSecs}s", "max")`,
        `summarize(cloudron.system.blockio-write, "${intervalSecs}s", "max")`,
        `summarize(cloudron.system.network-read, "${intervalSecs}s", "max")`,
        `summarize(cloudron.system.network-write, "${intervalSecs}s", "max")`,

    ];

    const results = [];

    for (const target of targets) {
        const query = {
            target: target,
            format: 'json',
            from: `-${fromSecs}s`,
            until: 'now',
            noNullPoints: !!noNullPoints
        };

        const [error, response] = await safe(superagent.get(graphiteUrl).query(query).timeout(30 * 1000).ok(() => true));
        if (error) throw new BoxError(BoxError.NETWORK_ERROR, error);
        if (response.status !== 200) throw new BoxError(BoxError.EXTERNAL_ERROR, `Unknown error with ${target}: ${response.status} ${response.text}`);

        results.push(response.body[0] && response.body[0].datapoints ? response.body[0].datapoints : []);
    }

    return {
        cpu: results[0],
        memory: results[1],
        swap: results[2],
        blockReadRate: results[3],
        blockWriteRate: results[4],
        networkReadRate: results[5],
        networkWriteRate: results[6],
        blockReadTotal: results[7][0] && results[7][0][0] ? results[7][0][0] : 0,
        blockWriteTotal: results[8][0] && results[8][0][0] ? results[8][0][0] : 0,
        networkReadTotal: results[9][0] && results[9][0][0] ? results[9][0][0] : 0,
        networkWriteTotal: results[10][0] && results[10][0][0] ? results[10][0][0] : 0,
    };
}

// CPU: stress --cpu 2 --timeout 60
async function getSystem(options) {
    assert.strictEqual(typeof options, 'object');

    const systemStats = await readSystemFromGraphite(options);

    const appStats = {};
    for (const app of await apps.list()) {
        appStats[app.id] = await getContainer(app.id, options);
    }

    const serviceStats = {};
    for (const serviceId of await services.listServices()) {
        serviceStats[serviceId] = await getContainer(serviceId, options);
    }

    return {
        ...systemStats, // { cpu, memory, swap, block{Read,Write}{Rate,Total}, network{Read,Write}{Rate,Total}
        apps: appStats,
        services: serviceStats,
    };
}

async function getSystemStream(options) {
    assert.strictEqual(typeof options, 'object');

    const intervalMsecs = options.intervalMsecs || 5000;
    let intervalId = null, oldMetrics = null;

    const metricsStream = new Readable({
        read(/*size*/) { /* ignored, we push via interval */ },
        destroy(error, callback) {
            clearInterval(intervalId);
            callback(error);
        }
    });

    intervalId = setInterval(async () => {
        const [error, metrics] = await safe(readSystemMetrics());
        if (error) return metricsStream.destroy(error);

        const cpuPercent = oldMetrics ? (metrics.userMsecs + metrics.sysMsecs - oldMetrics.userMsecs - oldMetrics.sysMsecs) * 100 / intervalMsecs : null;
        const blockReadRate = oldMetrics ? (metrics.blockRead - oldMetrics.blockRead) / (intervalMsecs/1000) : null;
        const blockWriteRate = oldMetrics ? (metrics.blockWrite - oldMetrics.blockWrite) / (intervalMsecs/1000) : null;
        const networkReadRate = oldMetrics ? (metrics.networkRead - oldMetrics.networkRead) / (intervalMsecs/1000) : null;
        const networkWriteRate = oldMetrics ? (metrics.networkWrite - oldMetrics.networkWrite) / (intervalMsecs/1000) : null;

        oldMetrics = metrics;

        const nowSecs = Date.now() / 1000; // to match graphite return value
        metricsStream.push(JSON.stringify({
            cpu: [ cpuPercent, nowSecs ],
            memory: [ metrics.memoryUsed, nowSecs ],
            swap: [ metrics.swapUsed, nowSecs ],

            blockReadRate: [ blockReadRate, nowSecs ],
            blockWriteRate: [ blockWriteRate, nowSecs ],
            blockReadTotal: metrics.blockRead,
            blockWriteTotal: metrics.blockWrite,

            networkReadRate: [ networkReadRate, nowSecs ],
            networkWriteRate: [ networkWriteRate, nowSecs ],
            networkReadTotal: metrics.networkRead,
            networkWriteTotal: metrics.networkWrite,
        }));
    }, intervalMsecs);

    return metricsStream;
}

async function getContainerStream(name, options) {
    assert.strictEqual(typeof name, 'string');
    assert.strictEqual(typeof options, 'object');

    let oldMetrics = null;

    const metricsStream = new Readable({
        read(/*size*/) { /* ignored, we push via interval */ },
        destroy(error, callback) {
            statsStream.destroy(); // double destroy is a no-op
            callback(error);
        }
    });

    const [error, statsStream] = await safe(docker.getStats(name, { stream: true }));
    if (error) throw new Error(`Container stopped or missing: ${error.message}`);

    statsStream.on('error', (error) => metricsStream.destroy(error));  // double destroy is a no-op
    statsStream.on('data', (data) => {
        const stats = JSON.parse(data.toString('utf8'));
        const metrics = translateContainerStatsSync(stats);

        const { ts, networkRead, networkWrite, blockRead, blockWrite, memoryUsed, cpuUsageMsecs } = metrics;

        const gap = oldMetrics ? (ts - oldMetrics.ts) : null;

        const cpuPercent = oldMetrics ? (cpuUsageMsecs - oldMetrics.cpuUsageMsecs) * 100 / gap : null;
        const blockReadRate = oldMetrics ? (blockRead - oldMetrics.blockRead) / (gap/1000) : null;
        const blockWriteRate = oldMetrics ? (blockWrite - oldMetrics.blockWrite) / (gap/1000) : null;
        const networkReadRate = oldMetrics ? (networkRead - oldMetrics.networkRead) / (gap/1000) : null;
        const networkWriteRate = oldMetrics ? (networkWrite - oldMetrics.networkWrite) / (gap/1000) : null;

        oldMetrics = metrics;

        const nowSecs = ts.getTime() / 1000; // to match graphite return value
        metricsStream.push(JSON.stringify({
            cpu: [ cpuPercent, nowSecs ],
            memory: [ memoryUsed, nowSecs ],

            blockReadRate: [ blockReadRate, nowSecs ],
            blockWriteRate: [ blockWriteRate, nowSecs ],
            blockReadTotal: metrics.blockRead,
            blockWriteTotal: metrics.blockWrite,

            networkReadRate: [ networkReadRate, nowSecs ],
            networkWriteRate: [ networkWriteRate, nowSecs ],
            networkReadTotal: metrics.networkRead,
            networkWriteTotal: metrics.networkWrite,
        }));
    });

    return metricsStream;
}