// rougly based on https://github.com/balena-io-modules/etcher-sdk/blob/f7d318fa67a10601a703b6b9758118825de9dc7a/examples/multi-destination.ts
// and https://github.com/balena-io/etcher/blob/b2c4f7a25004bd83a2dc74ccb31be96f49523223/lib/gui/modules/child-writer.ts#L114


// This file is meant to be invoked by runNodeWithElevatedPermissions.js
// it is spawned as a separate process so it can have admin permissions to write disks.
// it connects to a node-ipc server hosted by the main electron process to get its instructions, 
// and it reports its status back to that server.

/*
 * Copyright 2017 balena.io
 *
 * Licensed 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.
 */

const fs = require('fs');
const util = require('util');
const path = require('path');
const Readable = require('stream').Readable;
const tar = require('tar');
const etcherSDK = require('etcher-sdk');
const balenaImageFS = require('balena-image-fs');
const balenaPartitionInfo = require('partitioninfo');
const balenaFileDisk = require('file-disk');
const cleanupTmpFiles = require('etcher-sdk/build/tmp').cleanupTmpFiles;
const nodeIPC = require('node-ipc');

const myUtils = require('./utils.js');

// https://en.wikipedia.org/wiki/Partition_type
// these are hexadecimal integer ids representing the ext filesystem
// in a MBR partition record.
const extFileSystemMBRPartitionTypes = {
  "93": 1,
  "83": 1,
  "43": 1,
}

//const rootsystemLocation = "/opt";

nodeIPC.config.id = process.env.IPC_CLIENT_ID;
nodeIPC.config.socketRoot = process.env.IPC_SOCKET_ROOT;

// NOTE: Ensure this isn't disabled, as it will cause
// the stdout maxBuffer size to be exceeded when flashing
nodeIPC.config.silent = true;

// > If set to 0, the client will NOT try to reconnect.
// See https://github.com/RIAEvangelist/node-ipc/
//
// The purpose behind this change is for this process
// to emit a "disconnect" event as soon as the GUI
// process is closed, so we can kill this process as well.
nodeIPC.config.stopRetrying = 0;

const DISCONNECT_DELAY = 100;
const IPC_SERVER_ID = process.env.IPC_SERVER_ID;

function terminate(exitCode) {
	nodeIPC.disconnect(IPC_SERVER_ID);
	process.nextTick(() => {
		process.exit(exitCode || 0);
	});
}


myUtils.startLoggingToFile("seedpacket-write-image-to-block-device.log")
let myLog = myUtils.myLog;
let isLoggingToServer = false;

const globalUncaughtError = (err) => {
  myLog("uncaughtException: " + err.stack);
  if(nodeIPC.of[IPC_SERVER_ID]) {
    nodeIPC.of[IPC_SERVER_ID].emit('error', errorToJSON(err));
  }
  setTimeout(() => {
    terminate(1);
  }, DISCONNECT_DELAY);
};

myLog("writeImageToBlockDevice.js starting, nodejs version: " +  process.version );

// see runNodeWithElevatedPermissions.js

nodeIPC.connectTo(IPC_SERVER_ID, () => {

  // monnkey patch myLog to send log messages to main process.
  const originalMyLog = myLog;
  myLog = (message) => {
    originalMyLog(message);

    // isLoggingToServer mutex to prevent stack overflow 
    // when .emit() causes the error event to be raised,
    // which in turn causes myLog() to be called again.
    if(!isLoggingToServer) {
      isLoggingToServer = true;
      if(nodeIPC.of[IPC_SERVER_ID]) {
        nodeIPC.of[IPC_SERVER_ID].emit('log', message);
      }
      isLoggingToServer = false;
    }

  };

  myLog("connected to " + IPC_SERVER_ID);

  // Remove leftover tmp files older than 1 hour
  cleanupTmpFiles(Date.now() - 60 * 60 * 1000);

  process.once('uncaughtException', globalUncaughtError);

  // Gracefully exit on the following cases. If the parent
  // process detects that child exit successfully but
  // no flashing information is available, then it will
  // assume that the child died halfway through.
  process.once('SIGINT', () => {
    myLog("SIGINT");
    terminate();
  });
  process.once('SIGTERM', () => {
    myLog("SIGTERM");
    terminate();
  });
  // The IPC server failed. Abort.
  nodeIPC.of[IPC_SERVER_ID].on('error', () => {
    myLog(`got error event from ${IPC_SERVER_ID}`);
    terminate();
  });
  nodeIPC.of[IPC_SERVER_ID].on('disconnect', () => {
    myLog(`got disconnect event from ${IPC_SERVER_ID}`);
		terminate();
  });
  
  nodeIPC.of[IPC_SERVER_ID].on('args', (argumentsArray) => {
    const argsString = JSON.stringify({
      imagePath: argumentsArray[0],
      overlay: "{...}",
      blockDevicePath: argumentsArray[2]
    });
    myLog(`got args event from ${IPC_SERVER_ID}: ${argsString}`);
    writeImageToBlockDevice(...argumentsArray).catch(err => {
      myLog(`writeImageToBlockDevice rejected with error: ${err.stack}`);
		  terminate(1);
    });
  });

  nodeIPC.of[IPC_SERVER_ID].on('connect', () => {
		myLog(
			`Successfully connected to IPC server: ${IPC_SERVER_ID}, socket root ${nodeIPC.config.socketRoot}`,
		);
		nodeIPC.of[IPC_SERVER_ID].emit('ready', {});
	});

});


async function writeImageToBlockDevice(imagePath, overlay,  blockDevicePath) {

  myLog(`writeImageToBlockDevice('${imagePath}', '${blockDevicePath}')`)

  const adapters = [
    new etcherSDK.scanner.adapters.BlockDeviceAdapter({
      includeSystemDrives: () => false,
      unmountOnSuccess: false,
      write: true,
      direct: true,
    }),
  ];
  const deviceScanner = new etcherSDK.scanner.Scanner(adapters);

  // Wait for the deviceScanner to be ready
  await new Promise((resolve, reject) => {
    deviceScanner.on('error', reject);
    deviceScanner.on('ready', resolve);
    deviceScanner.start();
  });

  myLog(`deviceScanner ready`)

  const destinationDrives = Array.from(deviceScanner.drives.values())
    .filter(x =>  x.path == blockDevicePath );

  myLog(`found ${Array.from(deviceScanner.drives.values()).length} drives. `);
  myLog(`destinationDrives: [${destinationDrives.map(x => x.path).join(', ')}]`);
  
  if(destinationDrives.length == 0) {
    throw new Error(`block device ${blockDevicePath} not found`);
  }

  if(destinationDrives.length > 1) {
    throw new Error(`more than 1 block device found matching ${blockDevicePath}`);
  }

  // default values lifted from:
  // https://github.com/balena-io/etcher/blob/a24be20e952ac041755b8e29c84cd72d1149d6c9/lib/gui/app/models/settings.ts#L75

  // decompressThenFlash usage example lifted from:
  //https://github.com/balena-io/etcher/blob/b2c4f7a25004bd83a2dc74ccb31be96f49523223/lib/gui/modules/child-writer.ts#L114

  let source = new etcherSDK.sourceDestination.File({ path: imagePath });

  source = await source.getInnerSource();

  myLog(`decompressThenFlash(...) `);

  await new Promise(async (resolve, reject) => {
    await etcherSDK.multiWrite.decompressThenFlash({
      source: source, // etcherSDK.sourceDestination.SourceDestination
      destinations: destinationDrives, // etcherSDK.sourceDestination.BlockDevice[];
      onProgress: (progress) => { // OnProgressFunction: (progress: MultiDestinationProgress) => void;
        // too verbose
        // myLog(`onProgress: ${JSON.stringify(progress, null, "  ")}`);
        const progressTypeStringIds = {
          "flashing": "description_Flashing2of3",
          "extracting": "description_Extracting1of3",
          "decompressing": "description_Extracting1of3",
          "verifying": "description_Verifying3of3"
        };
  
        if(!progressTypeStringIds[progress.type] ) {
          myLog(`progressTypeStringIds does not include: ${progress.type}`);
        }
  
        nodeIPC.of[IPC_SERVER_ID].emit('status', {
          progress: progress.percentage/100,
          phase: progressTypeStringIds[progress.type],
          bytesPerSecond: progress.speed,
        });
      },
      onFail: (destination, err) => {
        myLog(`decompressThenFlash onFail(): ${JSON.stringify(destination)}: ${err}`);
        reject(err);
      },
      verify: true, // boolean;
      trim: true, // autoBlockmapping: true,
      numBuffers: 256, // number of 1mb buffers to use when writing.
      decompressFirst: true,
    });
    
    resolve();
  });
  

  myLog(`decompressThenFlash resolved! Now inspecting the disk ${destinationDrives[0].path} `);
  
  await balenaFileDisk.withOpenFile(destinationDrives[0].path, 'r+', async (handle) => {

    myLog(`balenaFileDisk.withOpenFile('${destinationDrives[0].path}, 'r+' (handle) => {`)
    myLog(`  called back with a file handle!`)

    const disk = new balenaFileDisk.FileDisk(handle);

    const partitionInfo = await balenaPartitionInfo.getPartitions(disk);

    const mainPartitions = [];

    for(const partition of partitionInfo.partitions) {

      myLog(`checking partition #${partition.index}, type ${partition.type.toString(16)}, offset ${partition.offset}`);

      // if( extFileSystemMBRPartitionTypes[partition.type.toString(16)] ) {
      // }
      const thePartition = partition.index;
      try {
        await balenaImageFS.interact(disk, thePartition, async (imageFs) => {
          files = await util.promisify(imageFs.readdir)("/");
          if(files.includes('bin') && files.includes('etc')) {
            myLog(`balenaImageFS.interact(fs => fs.readdir('/')): located main file system on partition #${thePartition}`);
            mainPartitions.push(thePartition);
          }
        });
      } catch (err) { 
        // no one cares as long as we get 1 mainPartition
        myLog(` partition #${partition.index} failed to mount/readdir: ${err}`);
      }
      
    }

    if(mainPartitions.length == 0) {
      throw new Error(`No main partition was found on ${destinationDrives[0].path}`);
    }
    if(mainPartitions.length > 1) {
      throw new Error(`More than one main partition was found on ${destinationDrives[0].path}`);
    }

    myLog(`writing configuration overlay onto the disk...`);

    await balenaImageFS.interact(disk, mainPartitions[0], async (imageFs) => { 

      const imageFsReadDirAsync = util.promisify(imageFs.readdir);
      const imageFsMkDirAsync = util.promisify(imageFs.mkdir);

      const knownPaths = {"/":true};
      (await imageFsReadDirAsync("/")).forEach(x => knownPaths[x] = {"$unexplored":true});

      for(const [path, file] of Object.entries(overlay)) {
        
        myLog(`trying to ensure directories exist for : ${path}\n`);
        //myLog(`knownPaths : ${JSON.stringify(knownPaths, null, "  ")}\n`);

        let pathSplit = path.split("/").filter(x => x != "");
        pathSplit = pathSplit.splice(0, pathSplit.length-1);

        //myLog(`pathSplit : ${JSON.stringify(pathSplit)}\n`);
        let currentKnownPaths = knownPaths;
        let currentPath = [];
        while(pathSplit.length > 0) {
          const nextPath = pathSplit.shift();
          currentPath.push(nextPath);

          //myLog(`currentPath: /${currentPath.join("/")}, nextPath: ${nextPath} \n`);
          if(!currentKnownPaths[nextPath]) {
            const toCreate = `/${currentPath.join("/")}`;
            const mode = file[toCreate] !== undefined ? file[toCreate] : file.mode;

            myLog(`mkdir: ${toCreate} mode: ${mode.toString(8)}`);
            await imageFsMkDirAsync(toCreate, mode);
            currentKnownPaths[nextPath] = {"$unexplored": false};
          } else if(currentKnownPaths[nextPath]["$unexplored"]) {
            myLog(`listing: /${currentPath.join("/")}`);
            (await imageFsReadDirAsync(`/${currentPath.join("/")}`)).forEach(x => currentKnownPaths[nextPath][x] = {"$unexplored":true});
            currentKnownPaths[nextPath]["$unexplored"] = false;
          }

          currentKnownPaths = currentKnownPaths[nextPath]
        }
        myLog(`writeFile: ${path}`);

        let originalContents = '';

        if(file.replaceLine) {
          originalContents = await util.promisify(imageFs.readFile)(path);
          //myLog(`originalContents: ${originalContents}`);
        }

        const writeStream = imageFs.createWriteStream(path, { mode: file.mode });

        const readStream = new Readable();
        readStream._read = () => {}; // _read is required but you can noop it
        readStream.pipe(writeStream);

        if(file.content) {
          readStream.push(new Buffer.from(file.content, "utf8"));
        } else if(file.replaceLine) {
          let replaced = false;
          const newContents = String(originalContents).split("\n").map(line => {
            if(line.match(new RegExp(file.replaceLine.match))) {
              myLog(`${path}: replacing line\n${line}\nwith\n${file.replaceLine.replace}\n`);
              replaced = true;
              return file.replaceLine.replace;
            }
            return line;
          }).join("\n");

          if(!replaced) {
            throw new Error(`file.replaceLine was specified but no line matching ${file.replaceLine.match} was found.`);
          }

          readStream.push(new Buffer.from(newContents, "utf8"));
        } else {
          throw new Error("file.content or file.replaceLine is required on overlay file")
        }

        readStream.push(null);
    
        await new Promise((resolve, reject) => {
          writeStream.on('error', reject);
          writeStream.on('close', resolve);
        });

      }

    });

  });

  myLog(`configuration of disk image complete!`);

  terminate(0);

}

function errorToJSON(err) {
  return {
    name: err.name,
    message: err.message,
    description: err.description,
    stack: err.stack,
    report: err.report,
    code: err.code,
    syscall: err.syscall,
    errno: err.errno,
    stdout: err.stdout,
    stderr: err.stderr,
    device: err.device,
  };
}