/**
 * Copyright 2013-2017  Zaid Abdulla
 *
 * This file is part of GenieACS.
 *
 * GenieACS is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * GenieACS is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with GenieACS.  If not, see <http://www.gnu.org/licenses/>.
 */
"use strict";

const fs = require("fs");
const os = require("os");

const config = require("./config");

const REOPEN_EVERY = 60000;

const LOG_FORMAT = config.get("LOG_FORMAT");
const ACCESS_LOG_FORMAT = config.get("ACCESS_LOG_FORMAT") || LOG_FORMAT;

const defaultMeta = {};

let LOG_SYSTEMD = false;
let ACCESS_LOG_SYSTEMD = false;

let LOG_FILE, ACCESS_LOG_FILE;

let logStream = fs.createWriteStream(null, {fd: process.stderr.fd});
let logStat = fs.fstatSync(logStream.fd);
let accessLogStream = fs.createWriteStream(null, {fd: process.stdout.fd});
let accessLogStat = fs.fstatSync(accessLogStream.fd);


// Reopen if original files have been moved (e.g. logrotate)
function reopen() {
  let counter = 1;

  if (LOG_FILE) {
    ++ counter;
    fs.stat(LOG_FILE, function(err, stat) {
      if (err && !err.message.startsWith("ENOENT:"))
        throw err;

      if (!(stat && stat.dev === logStat.dev && stat.ino === logStat.ino)) {
        logStream.end();
        logStream = fs.createWriteStream(null,
          {fd: fs.openSync(LOG_FILE, "a")});
        logStat = fs.fstatSync(logStream.fd);
      }

      if (-- counter === 0)
        setTimeout(reopen, REOPEN_EVERY - (Date.now() % REOPEN_EVERY)).unref();
    });
  }

  if (ACCESS_LOG_FILE) {
    ++ counter;
    fs.stat(ACCESS_LOG_FILE, function(err, stat) {
      if (err && !err.message.startsWith("ENOENT:"))
        throw err;

      if (!(stat && stat.dev === accessLogStat.dev && stat.ino === accessLogStat.ino)) {
        accessLogStream.end();
        accessLogStream = fs.createWriteStream(null,
          {fd: fs.openSync(ACCESS_LOG_FILE, "a")});
        accessLogStat = fs.fstatSync(accessLogStream.fd);
      }

      if (-- counter === 0)
        setTimeout(reopen, REOPEN_EVERY - (Date.now() % REOPEN_EVERY)).unref();
    });
  }

  if (-- counter === 0)
    setTimeout(reopen, REOPEN_EVERY - (Date.now() % REOPEN_EVERY)).unref();
}


function init(service, version) {
  defaultMeta.hostname = os.hostname();
  defaultMeta.pid = process.pid;
  defaultMeta.name = `genieacs-${service}`;
  defaultMeta.version = version;

  LOG_FILE = config.get(`${service.toUpperCase()}_LOG_FILE`);
  ACCESS_LOG_FILE = config.get(`${service.toUpperCase()}_ACCESS_LOG_FILE`);

  if (LOG_FILE) {
    logStream = fs.createWriteStream(null,
      {fd: fs.openSync(LOG_FILE, "a")});
    logStat = fs.fstatSync(logStream.fd);
  }

  if (ACCESS_LOG_FILE) {
    accessLogStream = fs.createWriteStream(null,
      {fd: fs.openSync(ACCESS_LOG_FILE, "a")});
    accessLogStat = fs.fstatSync(accessLogStream.fd);
  }

  // Determine if logs are going to journald
  const JOURNAL_STREAM = process.env["JOURNAL_STREAM"];

  if (JOURNAL_STREAM) {
    let [dev, inode] = JOURNAL_STREAM.split(":");
    dev = parseInt(dev);
    inode = parseInt(inode);

    LOG_SYSTEMD = (logStat.dev === dev && logStat.ino === inode);
    ACCESS_LOG_SYSTEMD = (accessLogStat.dev === dev && accessLogStat.ino === inode);
  }

  if (LOG_FILE || ACCESS_LOG_FILE) {
    // Can't use setInterval as we need all workers to cehck at the same time
    setTimeout(reopen, REOPEN_EVERY - (Date.now() % REOPEN_EVERY)).unref();
  }
}


function close() {
  accessLogStream.end();
  logStream.end();
}


function flatten(details) {
  if (details.sessionContext) {
    details.deviceId = details.sessionContext.deviceId;
    details.remoteAddress = details.sessionContext.httpRequest.connection.remoteAddress;
    delete details.sessionContext;
  }

  if (details.exception) {
    details.exceptionName = details.exception.name;
    details.exceptionMessage = details.exception.message;
    details.exceptionStack = details.exception.stack;
    delete details.exception;
  }

  if (details.task) {
    details.taskId = details.task._id;
    delete details.task;
  }

  if (details.rpc) {
    if (details.rpc.acsRequest) {
      details.acsRequestId = details.rpc.id;
      details.acsRequestName = details.rpc.acsRequest.name;
      if (details.rpc.acsRequest.commandKey)
        details.acsRequestCommandKey = details.rpc.acsRequest.commandKey;
    }
    else if (details.rpc.cpeRequest) {
      details.cpeRequestId = details.rpc.id;
      if (details.rpc.cpeRequest.name === "Inform") {
        details.informEvent = details.rpc.cpeRequest.event.join(",");
        details.informRetryCount = details.rpc.cpeRequest.retryCount;
      }
      else {
        details.cpeRequestName = details.rpc.cpeRequest.name;
        if (details.rpc.cpeRequest.commandKey)
          details.cpeRequestCommandKey = details.rpc.cpeRequest.commandKey;
      }
    }
    else if (details.rpc.cpeFault) {
      details.acsRequestId = details.rpc.id;
      details.cpeFaultCode = details.rpc.cpeFault.faultCode;
      details.cpeFaultString = details.rpc.cpeFault.faultString;
    }
    delete details.rpc;
  }

  if (details.fault) {
    details.faultCode = details.fault.code;
    details.faultMessage = details.fault.message;
    delete details.fault;
  }

  return details;
}


function formatJson(details, systemd) {
  if (systemd) {
    let severity = "";
    if (details.severity === "info")
      severity = "<6>";
    else if (details.severity === "warn")
      severity = "<4>";
    else if (details.severity === "error")
      severity = "<3>";

    return `${severity}${JSON.stringify(flatten(details))}${os.EOL}`;
  }

  return `${JSON.stringify(flatten(details))}${os.EOL}`;
}


function formatSimple(details, systemd) {
  flatten(details);

  let remote = "";
  if (details.remoteAddress) {
    if (details.deviceId)
      remote = `${details.remoteAddress} ${details.deviceId}: `;
    else
      remote = `${details.remoteAddress}: `;
  }

  const keys = Object.keys(details);
  const skip = {
    deviceId: 1,
    remoteAddress: 1,
    severity: 1,
    timestamp: 1,
    message: 1
  };

  let meta = "";

  let kv = [];
  for (let k of keys)
    if (!skip[k])
      kv.push(`${k}=${JSON.stringify(details[k])}`);

  if (kv.length)
    meta = `; ${kv.join(" ")}`;

  if (systemd) {
    let severity = "";
    if (details.severity === "info")
      severity = "<6>";
    else if (details.severity === "warn")
      severity = "<4>";
    else if (details.severity === "error")
      severity = "<3>";

    return `${severity}${remote}${details.message}${meta}${os.EOL}`;
  }

  return `${details.timestamp} [${details.severity.toUpperCase()}] ${remote}${details.message}${meta}${os.EOL}`;
}


function log(details) {
  details.timestamp = new Date().toISOString();
  if (LOG_FORMAT === "json") {
    details = Object.assign({}, defaultMeta, details);
    logStream.write(formatJson(details, LOG_SYSTEMD));
  } else {
    logStream.write(formatSimple(details, LOG_SYSTEMD));
  }
}


function info(details) {
  details.severity = "info";
  log(details);
}


function warn(details) {
  details.severity = "warn";
  log(details);
}


function error(details) {
  details.severity = "error";
  log(details);
}


function accessLog(details) {
  details.timestamp = new Date().toISOString();
  if (ACCESS_LOG_FORMAT === "json") {
    Object.assign(details, defaultMeta);
    accessLogStream.write(formatJson(details, ACCESS_LOG_SYSTEMD));
  } else {
    accessLogStream.write(formatSimple(details, ACCESS_LOG_SYSTEMD));
  }
}


function accessInfo(details) {
  details.severity = "info";
  accessLog(details);
}


function accessWarn(details) {
  details.severity = "warn";
  accessLog(details);
}


function accessError(details) {
  details.severity = "error";
  accessLog(details);
}


exports.init = init;
exports.close = close;
exports.info = info;
exports.warn = warn;
exports.error = error;
exports.accessInfo = accessInfo;
exports.accessWarn = accessWarn;
exports.accessError = accessError;