// Run this script in node.js
//
// First install deps:
// sudo apt-get install libexiv2-12 libexiv2-dev
// npm install exiv2
//
// Argument #1 = .JPG relative path
// Argument #2 = overwrite file true/false. False will create a new file with ".jpg.jpg" extension
// "raspicam-fix-exif.js"

ar ex = require('exiv2');
var fs = require('fs');

// overwrite or not? true/false
var _OVERWRITE=process.argv[3];

// the file name to read exif
//example '/tmp/RPIPICI13120400001.jpg';
var fName = process.argv[2];

// make a backup which should be overwriten
// with the fixed tags
//
function copyFile(origFName, newFName, cb) {
  var fCalledBack = false;

  var readIn = fs.createReadStream(origFName);
  readIn.on("error", function(err) {
    callback(err);
  });

  var writeOut = fs.createWriteStream(newFName);
  writeOut.on("error", function(err) {
    callback(err);
  });

  writeOut.on("close", function(ex) {
    callback();
  });
  readIn.pipe(wr);

  function callback(err) {
    if (!fCalledBack) {
      // call the callback function which was passed in.
      cb(origFName, err);

      // to be safe, in case err/close trigger arrives more than once
      fCalledBack = true;
    }
  }
};

// Get the exif info
//
function getImageTags(fName, cb) {
  console.log ("reading exif... " + fName);

  ex.getImageTags(fName, function(err, tags) {
    if (err) throw err;

    var dateTime = tags["Exif.Image.DateTime"];
    var dateTimeOriginal = tags["Exif.Photo.DateTimeOriginal"];
    var dateTimeDigitized = tags["Exif.Photo.DateTimeDigitized"];

    // print the old values
    console.log("\tFilename: " + fName + " :: \n" +
                "\tDateTime: " + dateTime + "\n" +
                "\tDateTimeOriginal: " + dateTimeOriginal + "\n" +
                "\tDateTimeDigitized: " + dateTimeDigitized + "\n");

    // fix the old values. Replace the ":" in between date and time with a " ".
    dateTime = dateTime.substr(0, 10) + " " + dateTime.substr(11, 20);
    dateTimeOriginal = dateTimeOriginal.substr(0, 10) + " " + dateTimeOriginal.substr(11, 20);
    dateTimeDigitized = dateTimeDigitized.substr(0, 10) + " " + dateTimeDigitized.substr(11, 20);

    // put then in a new tag array
    var newTags = {
      "Exif.Image.DateTime" : dateTime,
      "Exif.Photo.DateTimeOriginal" : dateTimeOriginal,
      "Exif.Photo.DateTimeDigitized" : dateTimeDigitized
    };

    // callback the caller
    cb (fName + (_OVERWRITE ? "" : ".jpg"), newTags);
  });
};

// Write out the new exif tags to the new jpg file
//
function setImageTags (newFName, newTags) {

  // now save the exif info
  ex.setImageTags(newFName, newTags, function(err) {
    console.log ("Exif set = " + (err ? ("Error: " + err) : "Success"));
  }); // set image
};

// Called either directly or after the copy file (when not overwriting) is complete
function retag(fName, err) {
  if (err) throw err;

  console.log ("getting....");
  // lets get the original tags
  getImageTags (fName, function (newFName, newTags) {
    console.log("Will soon set tags to " + newFName);
    setImageTags (newFName, newTags);
  });
};

console.log ("working....Overwrite=" + _OVERWRITE + " Fname=" + fName);

// This is the primary control. Either overwrite or not.
if (_OVERWRITE) {
  console.log ("overwriting\n");

  // get the tags. Overwrite the original file with the fixed date flags.
  retag(fName);
}
else {

  // Do not overwrite the file. Instead name it "*.jgp.jpg"
  console.log ("not overwrite\n");

  // Start by copying the file where the new exif info will go
  // Pass the "retag" function as the callback, so once the copy
  // is complete, the flow will continue as normal
  //
  copyFile (fName, fName + ".jpg", retag);
}