callback mania

exif.js

var ExifImage = require('exif').ExifImage;
var image = 'DSC_8041.jpg';

// Step 5, send data off
function finish(EXIF) {
    console.log(`Finished EXIF: ` + JSON.stringify(EXIF));
    return EXIF;
}

// Step 4, reformat data
function doMath(result, string, Image, Camera, Settings, callback) {
    var nameJeff = `${result[0]}/${result[1]}`;
    console.log(`${result[0]}/${result[1]}`);
    //console.log('This: ' + Settings.shutterSpeed);
    Settings.shutterSpeed = nameJeff;
    console.log('========================');
    console.log('Updated Image: ' + JSON.stringify(Image));
    console.log('Updated Camera: ' + JSON.stringify(Camera));
    console.log('Updated Settings: ' + JSON.stringify(Settings));
    var EXIF = {
        'Image': {
            'Filename': Image.Filename,
            'Author': Image.Author,
            'dateTaken': Image.dateTaken,
            'Resolution': Image.Resolution
        },
        'Camera': {
            'Make': Camera.Make,
            'Model': Camera.Model,
            'Lens': Camera.LensModel
        },
        'Settings': {
            'focalLength': Settings.FocalLength,
            'shutterSpeed': Settings.shutterSpeed,
            'Aperture': Settings.Aperture,
            'ISO': Settings.ISO,
            'Flash': Settings.Flash
        }
    };
    callback(EXIF);
}

// Step 3, convert shutter
function convertShutter(string, callback, Image, Camera, Settings) {
    var input = string;
    var length = string.length;
    var index = [];

    for (i = 0; i < length; i++) {
        var theIndex = input.substr(i, 1)
        index[i] = theIndex;
    }
    var arrLength = index.length;
    var partOne = []; // Zeros
    var partTwo = []; // Numbers larger than 0
    for (i = 0; i < arrLength; i++) {
        var value = index[i];
        if (value <= 0) {
            partOne += value
        } else if (value === '.') {
            partOne += value
        } else if (value > 0 && value != null) {
            partTwo += value
        } else {
            console.log(`${value} at ${i} did not fall in a category!`)
        }
    }

    var arr1Len = partOne.length - 2;
    var arr2Len = partTwo.length;

    var power = Math.pow(10, arr1Len + arr2Len);

    // Factoring Numerator, the first index of the second array (125 in this case)
    var stepOneNumerator = partTwo;

    // Take the power (100,000) and divide by the numerator (125) to get 800 (125 goes into 100,000 800 times)
    var factoring = power / stepOneNumerator

    // result[0] = Numerator, result[0] = denominator (result = regular shutter speed)
    var result = [1, factoring];

    callback(result, input, Image, Camera, Settings, finish);
}

// Get Exif Data 
// Step Two
function cb(Image, Camera, Settings) {

    convertShutter(Settings.shutterSpeed, doMath, Image, Camera, Settings);

}


// Step One
function getEXIF(image, callback) {
    try {
        new ExifImage({ image: image }, function (error, exifData) {
            if (error)
                console.log('EXIF Error: ' + error.message);
            else
                // convert shutter to string
                var oldSpeed = "" + exifData.exif.ExposureTime + "";
                var Image = {'Filename': image, 'Author': 'Cody Kaczynski', 'dateTaken': exifData.exif.DateTimeOriginal, 'Resolution': `${exifData.exif.FocalPlaneXResolution} x ${exifData.exif.FocalPlaneYResolution}`};
                var Camera = {'Make': exifData.image.Make, 'Model': exifData.image.Model, 'Lens': exifData.image.LensModel};
                var Settings = {'focalLength': exifData.exif.FocalLength, 'shutterSpeed': oldSpeed, 'Aperture': exifData.exif.FNumber, 'ISO': exifData.exif.ISO, 'Flash': exifData.exif.Flash};

                console.log(`Image Info: ` + JSON.stringify(Image));
                console.log(`Camera Info: ` + JSON.stringify(Camera));
                console.log(`Settings: ` + JSON.stringify(Settings));

                callback(Image, Camera, Settings)
        });
    } catch (error) {
        console.log('Error: ' + error.message);
    }
}


// Step One
getEXIF(image, cb);



// getEXIF grabs EXIF info, formats it a little, passes it to a callback that converts the shutter speed, then passes that to a callback that formats data AGAIN, then passes to another callback for the final output

OUTPUT:

Image Info: {"Filename":"DSC_8041.jpg","Author":"Cody Kaczynski","dateTaken":"2016:03:19 19:10:04","Resolution":"2595.2521362304688 x 2595.2521362304688"}
Camera Info: {"Make":"NIKON CORPORATION","Model":"NIKON D3200"}
Settings: {"focalLength":35,"shutterSpeed":"0.00125","Aperture":1.8,"ISO":100,"Flash":0}
1/800
========================
Updated Image: {"Filename":"DSC_8041.jpg","Author":"Cody Kaczynski","dateTaken":"2016:03:19 19:10:04","Resolution":"2595.2521362304688 x 2595.2521362304688"}
Updated Camera: {"Make":"NIKON CORPORATION","Model":"NIKON D3200"}
Updated Settings: {"focalLength":35,"shutterSpeed":"1/800","Aperture":1.8,"ISO":100,"Flash":0}

Finished EXIF: {"Image":{"Filename":"DSC_8041.jpg","Author":"Cody Kaczynski","dateTaken":"2016:03:19 19:10:04","Resolution":"2595.2521362304688 x 2595.2521362304688"},"Camera":{"Make":"NIKON C
ORPORATION","Model":"NIKON D3200"},"Settings":{"shutterSpeed":"1/800","Aperture":1.8,"ISO":100,"Flash":0}}