'use strict';
var Cesium = require('cesium');
var fsExtra = require('fs-extra');
var GltfPipeline = require('gltf-pipeline').Pipeline;
var path = require('path');
var Promise = require('bluebird');
var createGltf = require('./gltf');
var loadObj = require('./obj');
var writeUris = require('./writeUris');

var fsExtraOutputJson = Promise.promisify(fsExtra.outputJson);

var defaultValue = Cesium.defaultValue;
var defined = Cesium.defined;
var DeveloperError = Cesium.DeveloperError;

module.exports = convert;

/**
 * A callback function that logs messages.
 * @callback Logger
 *
 * @param {String} message The message to log.
 */
var defaultLogger = function(message) {
    console.log(message);
};

/**
 * Converts an obj file to a glTF file.
 *
 * @param {String} objPath Path to the obj file.
 * @param {String} gltfPath Path of the converted glTF file.
 * @param {Object} [options] An object with the following properties:
 * @param {Boolean} [options.binary=false] Save as binary glTF.
 * @param {Boolean} [options.separate=false] Writes out separate geometry data files, shader files, and textures instead of embedding them in the glTF.
 * @param {Boolean} [options.separateTextures=false] Write out separate textures only.
 * @param {Boolean} [options.compress=false] Quantize positions, compress texture coordinates, and oct-encode normals.
 * @param {Boolean} [options.optimize=false] Use the optimization stages in the glTF pipeline.
 * @param {Boolean} [options.optimizeForCesium=false] Optimize the glTF for Cesium by using the sun as a default light source.
 * @param {Boolean} [options.generateNormals=false] Generate normals if they are missing.
 * @param {Boolean} [options.ao=false] Apply ambient occlusion to the converted model.
 * @param {Boolean} [options.kmc=false] Output glTF with the KHR_materials_common extension.
 * @param {Boolean} [options.textureCompressionOptions] Options sent to the compressTextures stage of gltf-pipeline.
 * @param {Boolean} [options.bypassPipeline=false] Bypass the gltf-pipeline for debugging purposes. This option overrides many of the options above and will save the glTF with the KHR_materials_common extension.
 * @param {Boolean} [options.hasTransparency=false] Do a more exhaustive check for texture transparency by looking at the alpha channel of each pixel.
 * @param {Boolean} [options.secure=false] Prevent the converter from reading image or mtl files outside of the input obj directory.
 * @param {Logger} [options.logger] A callback function for handling logged messages. Defaults to console.log.
 */
function convert(objPath, gltfPath, options) {
    return new Promise(function(resolve, reject) {
        options = defaultValue(options, {});
        var binary = defaultValue(options.binary, false);
        var separate = defaultValue(options.separate, false);
        var separateTextures = defaultValue(options.separateTextures, false) || separate;
        var compress = defaultValue(options.compress, false);
        var optimize = defaultValue(options.optimize, false);
        var optimizeForCesium = defaultValue(options.optimizeForCesium, false);
        var generateNormals = defaultValue(options.generateNormals, false);
        var ao = defaultValue(options.ao, false);
        var kmc = defaultValue(options.kmc, false);
        var textureCompressionOptions = options.textureCompressionOptions;
        var bypassPipeline = defaultValue(options.bypassPipeline, false);
        var logger = defaultValue(options.logger, defaultLogger);
        options.logger = logger;
        options.hasTransparency = defaultValue(options.hasTransparency, false);
        options.secure = defaultValue(options.secure, false);

        if (!defined(objPath)) {
            throw new DeveloperError('objPath is required');
        }

        if (!defined(gltfPath)) {
            throw new DeveloperError('gltfPath is required');
        }

        var objExtension = path.extname(objPath).toLowerCase();
        if (objExtension !== '.obj') {
            throw new DeveloperError('Invalid obj path "' + objPath + '"');
        }

        var extension = path.extname(gltfPath).toLowerCase();
        if (extension !== '.gltf' && extension !== '.glb') {
            throw new DeveloperError('Invalid gltf path "' + gltfPath + '"');
        }

        var basePath = path.dirname(gltfPath);
        var modelName = path.basename(gltfPath, path.extname(gltfPath));
        if (extension === '.glb') {
            binary = true;
            if (bypassPipeline) {
                logger('--bypassPipeline does not convert to binary glTF, saving as .gltf');
                extension = '.gltf';
            }
        }
        gltfPath = path.join(path.dirname(gltfPath), modelName + extension);

        var aoOptions = ao ? {} : undefined;
        var kmcOptions = kmc ? {} : undefined;

        var pipelineOptions = {
            createDirectory : false,
            basePath : basePath,
            binary : binary,
            embed : !separate,
            embedImage : !separateTextures,
            quantize : compress,
            compressTextureCoordinates : compress,
            encodeNormals : compress,
            preserve : !optimize,
            optimizeForCesium : optimizeForCesium,
            smoothNormals : generateNormals,
            aoOptions : aoOptions,
            kmcOptions : kmcOptions,
            textureCompressionOptions : textureCompressionOptions
        };

        return loadObj(objPath, options)
            .then(function(objData) {
                return createGltf(objData);
            })
            .then(function(gltf) {
                return writeUris(gltf, gltfPath, separate, separateTextures, logger);
            })
            .then(function(gltf) {
                if (bypassPipeline) {
                    return convert._outputJson(gltfPath, gltf);
                } else {
                    return GltfPipeline.processJSONToDisk(gltf, gltfPath, pipelineOptions);
                }
            })
            .then(resolve)
            .catch(reject);
    });
}

/**
 * Exposed for testing
 *
 * @private
 */
convert._outputJson = fsExtraOutputJson;