xfdf.js

/**
 * Created by Administrator on 2017-03-22.
 */
var builder = require('xmlbuilder'),
    fs      = require('fs'),
    _       = require('lodash');

module.exports = XFDF;

function XFDF(opts) {
    var self = this;
    if (!(this instanceof XFDF)) return new XFDF(opts);
    if (!opts) opts = {};

    // Load options and set defaults
    self._opts                = {};
    self._opts.format         = opts.format || { pretty: true, indent: '  ', newline: '\n' };
    self._opts.translateBools = opts.translateBools === false ? false : true;
    self._opts.pdf            = opts.pdf || null;

    self._fields      = [];
    self._annotations = [];
    return self;
}

XFDF.prototype.addField = function(field, value) {

    // Check if current field is invalid, if it is, throw an error
    if ( !this.validField(field, value) ) {
        throw new Error('Trying to add a field, but field is invalid: ' + JSON.stringify(field, null, 2));
    }

    // Everything looks good, push field onto fields array

    // Check if value is an array that needs to be pushed
    if ( value instanceof Array ) {
        for ( var i = 0; i < value.length; i++ ) {
            this._fields.push({ name: field, value: value[i] });
        }
    }
    // Push single value
    else {
        this._fields.push({ name: field, value: value});
    }

    return this;

};

XFDF.prototype.addAnnotation = function(annotations) {
    //TODO
};

// Semantic shorthand for addAnnotation w/ array
XFDF.prototype.addAnnotations = function(annotations) {
    //TODO
};

XFDF.prototype.fromJSON = function(obj) {

    var self = this;

    if ( !obj || typeof obj !== 'object' ) {
        throw new Error('Calling fromJSON(), but argument supplied is not an object.');
    }

    if ( !obj.fields ) {
        throw new Error('Calling fromJSON(), but object provided does not have "field" key.');
    }

    // Loop over fields and add them to current object
    _.forEach(obj.fields, function(value, field) {
        self.addField(field, value);
    });

    // TODO add annotations loop

    return this;
};

XFDF.prototype.fromJSONFile = function(path, callback) {

    var self = this;

    if ( !path || typeof path !== 'string' ) {
        throw new Error('Calling fromJSONFile(), but no file path argument provided.');
    }

    if ( !callback || typeof callback !== 'function' ) {
        throw new Error('Calling fromJSONFile(), but no callback argument provided.');
    }

    fs.readFile(path, 'utf8', function(err, data) {

        // Check if error during read
        if ( err ) {
            return callback(err);
        }

        // Lets try to JSON parse the file contents
        var obj;

        try {
            obj = JSON.parse(data);
        }
        catch (error) {
            // Erp! Die
            return callback(error);
        }

        // Slurp went well, sent data object to #fromJSON()
        self.fromJSON(obj);

        return callback(null);

    });

};

// This method is used to validate a field object, it only tests to make sure name and values
//  exists as keys
XFDF.prototype.validField = function(field, value) {

    if ( !field || (!(_.isString(value) || _.isBoolean(value)) && !value && value !== 0)) return false;

    if ( typeof field !== 'string' ) return false;

    return true;
};

XFDF.prototype.generate = function() {
    var self = this;

    if ( self._fields.length === 0 ) {
        throw new Error('Calling generate() but no fields have been added.');
    }

    // Declare Root
    var rootEle = builder.create('xfdf',
        { version: '1.0', encoding: 'UTF-8'});

    // Add XFDF require attributes
    rootEle.att({ xmlns: 'http://ns.adobe.com/xfdf/'});
    rootEle.att({'xml:space': 'preserve' });

    // Create f element, if a pdf was supplied
    if ( self._opts.pdf ) {
        rootEle.ele('f', { href: this._opts.pdf });
    }

    // Create <fields> element
    var fieldsEle = rootEle.ele('fields');

    // Iterate through fields and write each one out
    _.forEach(self._fields, function(field) {
        var name  = field.name,
            value = field.value;

        // Create field element with attribute of name
        var currentFieldEle = fieldsEle.ele('field', { name: name });

        // translateBool if set
        if ( self._opts.translateBools && typeof value === 'boolean' ) {

            // XFDF Translates a true to 'Yes' and a false to 'Off' for checkboxes and radios
            value = value ? 'Yes' : 'Off';
        }

        // Create value element inside of field element
        currentFieldEle.ele('value', {}, value);
    });

    return rootEle.end(self._opts.format);

};

XFDF.prototype.generateToFile = function(path, callback) {

    // Generate and get xfdf string
    var xfdfString = this.generate();

    // Write file out
    fs.writeFile(path, xfdfString, callback);

};