"use strict";
var fs = require('fs-extra');
var defined = require('cesium').defined;

module.exports = {
    getDefault : getDefault,
    parse : parse
};

function createMaterial() {
    return {
        ambientColor : undefined,               // Ka
        emissionColor : undefined,              // Ke
        diffuseColor : undefined,               // Kd
        specularColor : undefined,              // Ks
        specularShininess : undefined,          // Ns
        alpha : undefined,                      // d / Tr
        ambientColorMap : undefined,            // map_Ka
        emissionColorMap : undefined,           // map_Ke
        diffuseColorMap : undefined,            // map_Kd
        specularColorMap : undefined,           // map_Ks
        specularShininessMap : undefined,       // map_Ns
        normalMap : undefined,                  // map_Bump
        alphaMap : undefined                    // map_d
    };
}

function getDefault() {
    var material = createMaterial();
    material.diffuseColor = [0.5, 0.5, 0.5, 1.0];
    return material;
}

function parse(mtlPath, done) {
    fs.readFile(mtlPath, 'utf8', function (error, contents) {
        if (error) {
            console.log('Could not read material file at ' + mtlPath + '. Using default material instead.');
            done({});
            return;
        }

        var materials = {};
        var material;

        var values;
        var value;
        var lines = contents.split('\n');
        var length = lines.length;
        for (var i = 0; i < length; ++i) {
            var line = lines[i].trim();
            if (/^newmtl /i.test(line)) {
                var name = line.substring(7).trim();
                material = createMaterial();
                materials[name] = material;
            } else if (/^Ka /i.test(line)) {
                values = line.substring(3).trim().split(' ');
                material.ambientColor = [
                    parseFloat(values[0]),
                    parseFloat(values[1]),
                    parseFloat(values[2]),
                    1.0
                ];
            } else if (/^Ke /i.test(line)) {
                values = line.substring(3).trim().split(' ');
                material.emissionColor = [
                    parseFloat(values[0]),
                    parseFloat(values[1]),
                    parseFloat(values[2]),
                    1.0
                ];
            } else if (/^Kd /i.test(line)) {
                values = line.substring(3).trim().split(' ');
                material.diffuseColor = [
                    parseFloat(values[0]),
                    parseFloat(values[1]),
                    parseFloat(values[2]),
                    1.0
                ];
            } else if (/^Ks /i.test(line)) {
                values = line.substring(3).trim().split(' ');
                material.specularColor = [
                    parseFloat(values[0]),
                    parseFloat(values[1]),
                    parseFloat(values[2]),
                    1.0
                ];
            } else if (/^Ns /i.test(line)) {
                value = line.substring(3).trim();
                material.specularShininess = parseFloat(value);
            } else if (/^d /i.test(line)) {
                value = line.substring(2).trim();
                material.alpha = parseFloat(value);
            }  else if (/^Tr /i.test(line)) {
                value = line.substring(3).trim();
                material.alpha = parseFloat(value);
            } else if (/^map_Ka /i.test(line)) {
                material.ambientColorMap = line.substring(7).trim();
            } else if (/^map_Ke /i.test(line)) {
                material.emissionColorMap = line.substring(7).trim();
            } else if (/^map_Kd /i.test(line)) {
                material.diffuseColorMap = line.substring(7).trim();
            } else if (/^map_Ks /i.test(line)) {
                material.specularColorMap = line.substring(7).trim();
            } else if (/^map_Ns /i.test(line)) {
                material.specularShininessMap = line.substring(7).trim();
            } else if (/^map_Bump /i.test(line)) {
                material.normalMap = line.substring(9).trim();
            } else if (/^map_d /i.test(line)) {
                material.alphaMap = line.substring(6).trim();
            }
        }
        
        if (defined(material.alpha)) {
            material.diffuseColor[3] = material.alpha;
        }

        done(materials);
    });
}