/**
 * This is a "compiler" for Amber code.
 * Put the following code into compiler.js:
 *     var amberc = require('amberc');
 *     var compiler = new amberc.Compiler('path/to/amber');
 *     var options = amberc.createDefaults();
 *     // edit options entries
 *     compiler.main(options);
 */

var path = require('path'),
    fs = require('fs'),
    Promise = require('es6-promise').Promise,
    requirejs = require('../node_modules/requirejs/bin/r');

/**
 * AmberCompiler constructor function.
 * amber_dir: points to the location of an amber installation
 */
function AmberCompiler(amber_dir) {
    if (amber_dir == null || !fs.existsSync(amber_dir)) {
        throw new Error('amber_dir needs to be a valid directory');
    }

    this.amber_dir = amber_dir;
    requirejs = requirejs.config({
        context: "amberc",
        nodeRequire: require,
        paths: {
            'amber': path.join(amber_dir, 'support'),
            'amber_core': path.join(amber_dir, 'src')
        }
    });
    // Important: in next list, boot MUST be first
    this.kernel_libraries = ['amber/boot',
        'amber_core/Kernel-Objects', 'amber_core/Kernel-Classes', 'amber_core/Kernel-Methods',
        'amber_core/Kernel-Collections', 'amber_core/Kernel-Infrastructure',
        'amber_core/Kernel-Exceptions', 'amber_core/Kernel-Announcements',
        'amber_core/Platform-Services', 'amber_core/Platform-Node'];
    this.compiler_libraries = this.kernel_libraries.concat(['amber/parser',
        'amber_core/Platform-ImportExport', 'amber_core/Compiler-Exceptions',
        'amber_core/Compiler-Core', 'amber_core/Compiler-AST', 'amber_core/Compiler-Exceptions',
        'amber_core/Compiler-IR', 'amber_core/Compiler-Inlining', 'amber_core/Compiler-Semantic']);
}


/**
 * Default values.
 */
var createDefaultConfiguration = function () {
    return {
        load: [],
        stFiles: [],
        jsGlobals: [],
        amdNamespace: 'amber_core',
        libraries: [],
        jsLibraryDirs: [],
        compile: [],
        compiled: [],
        outputDir: undefined,
        verbose: false
    };
};


/**
 * Main function for executing the compiler.
 * If check_configuration_ok() returns successfully
 * the configuration is used to trigger the following compilation steps.
 */
AmberCompiler.prototype.main = function (configuration, finished_callback) {
    console.time('Compile Time');

    if (configuration.amdNamespace.length === 0) {
        configuration.amdNamespace = 'amber_core';
    }

    if (configuration.jsLibraryDirs != null) {
        configuration.jsLibraryDirs.push(path.join(this.amber_dir, 'src'));
        configuration.jsLibraryDirs.push(path.join(this.amber_dir, 'support'));
    }

    console.ambercLog = console.log;
    if (false === configuration.verbose) {
        console.log = function () {
        };
    }

    // the evaluated compiler will be stored in this variable (see create_compiler)
    configuration.core = {};
    configuration.globals = {};
    configuration.kernel_libraries = this.kernel_libraries;
    configuration.compiler_libraries = this.compiler_libraries;
    configuration.amber_dir = this.amber_dir;

    check_configuration(configuration)
        .then(collect_st_files)
        .then(resolve_kernel)
        .then(create_compiler)
        .then(compile)
        .then(category_export)
        .then(verify)
        .then(function () {
            console.timeEnd('Compile Time');
        }, function (error) {
            console.error(error);
        })
        .then(function () {
            console.log = console.ambercLog;
            finished_callback && finished_callback();
        });
};


/**
 * Check if the passed in configuration object has sufficient/nonconflicting values.
 * Returns a Promise which resolves into the configuration object.
 */
function check_configuration(configuration) {
    return new Promise(function (resolve, reject) {
        if (configuration == null) {
            reject(Error('AmberCompiler.check_configuration_ok(): missing configuration object'));
        }

        if (0 === configuration.stFiles.length) {
            reject(Error('AmberCompiler.check_configuration_ok(): no files to compile specified in configuration object'));
        }

        resolve(configuration);
    });
}


/**
 * Check if the file given as parameter exists in any of the following directories:
 *  1. current local directory
 *  2. configuration.jsLibraryDirs
 *  3. $AMBER/src/
 *  3. $AMBER/support/
 *
 * @param filename name of a file without '.js' prefix
 * @param configuration the main amberc configuration object
 */
function resolve_js(filename, configuration) {
    var baseName = path.basename(filename, '.js');
    var jsFile = baseName + '.js';
    return resolve_file(jsFile, configuration.jsLibraryDirs);
}


/**
 * Check if the file given as parameter exists in any of the following directories:
 *  1. current local directory
 *  2. $AMBER/
 *
 * @param filename name of a .st file
 * @param configuration the main amberc configuration object
 */
function resolve_st(filename, configuration) {
    return resolve_file(filename, [configuration.amber_dir]);
}


/**
 * Resolve the location of a file given as parameter filename.
 * First check if the file exists at given location,
 * then check in each of the directories specified in parameter searchDirectories.
 */
function resolve_file(filename, searchDirectories) {
    return new Promise(function (resolve, reject) {
        console.log('Resolving: ' + filename);
        fs.exists(filename, function (exists) {
            if (exists) {
                resolve(filename);
            } else {
                var alternativeFile = '';
                // check for filename in any of the given searchDirectories
                var found = searchDirectories.some(function (directory) {
                    alternativeFile = path.join(directory, filename);
                    return fs.existsSync(alternativeFile);
                });
                if (found) {
                    resolve(alternativeFile);
                } else {
                    reject(Error('File not found: ' + alternativeFile));
                }
            }
        });
    });
}


/**
 * Resolve st files given by stFiles and add them to configuration.compile.
 * Returns a Promise which resolves into the configuration object.
 */
function collect_st_files(configuration) {
    return Promise.all(
        configuration.stFiles.map(function (stFile) {
            return resolve_st(stFile, configuration);
        })
    )
        .then(function (data) {
            configuration.compile = configuration.compile.concat(data);
            return configuration;
        });
}


/**
 * Resolve .js files needed by kernel.
 * Returns a Promise which resolves into the configuration object.
 */
function resolve_kernel(configuration) {
    var kernel_files = configuration.kernel_libraries.concat(configuration.load);
    return Promise.all(
        kernel_files.map(function (file) {
            return resolve_js(file, configuration);
        })
    )
        .then(function (data) {
            // boot.js and Kernel files need to be used first
            // otherwise the global objects 'core' and 'globals' are undefined
            configuration.libraries = data.concat(configuration.libraries);
            return configuration;
        });
}


function withImportsExcluded(data) {
    var srcLines = data.split(/\r\n|\r|\n/), dstLines = [], doCopy = true;
    srcLines.forEach(function (line) {
        if (line.replace(/\s/g, '') === '//>>excludeStart("imports",pragmas.excludeImports);') {
            doCopy = false;
        } else if (line.replace(/\s/g, '') === '//>>excludeEnd("imports");') {
            doCopy = true;
        } else if (doCopy) {
            dstLines.push(line);
        }
    });
    return dstLines.join('\n');
}

/**
 * Resolve .js files needed by compiler, read and eval() them.
 * The finished Compiler gets stored in configuration.{core,globals}.
 * Returns a Promise object which resolves into the configuration object.
 */
function create_compiler(configuration) {
    var compiler_files = configuration.compiler_libraries;
    var include_files = configuration.load;
    return new Promise(function (resolve, reject) {
        requirejs(compiler_files, function (boot) {
            configuration.core = boot.api;
            configuration.globals = boot.globals;
            resolve(configuration);
        }, function (err) {
            reject(err);
        });
    })
        .then(function (configuration) {
            var files = []; // TODO load -L libraries while filtering their imports
            files.forEach(function (data) {
                data = data + '';
                data = withImportsExcluded(data);
                //builder.add(data);
            });

            configuration.core.initialize();
            console.log('Compiler loaded');

            configuration.globals.ErrorHandler._register_(configuration.globals.RethrowErrorHandler._new());

            if (0 !== configuration.jsGlobals.length) {
                var jsGlobalVariables = configuration.core.globalJsVariables;
                jsGlobalVariables.push.apply(jsGlobalVariables, configuration.jsGlobals);
            }

            return configuration;
        });
}


/**
 * Compile all given .st files by importing them.
 * Returns a Promise object that resolves into the configuration object.
 */
function compile(configuration) {
    // return function which does the actual work
    // and use the compile function to reference the configuration object
    return Promise.all(
        configuration.compile.map(function (stFile) {
            return new Promise(function (resolve, reject) {
                if (/\.st/.test(stFile)) {
                    console.ambercLog('Reading: ' + stFile);
                    fs.readFile(stFile, 'utf8', function (err, data) {
                        if (!err)
                            resolve(data);
                        else
                            reject(Error('Could not read: ' + stFile));
                    });
                }
            });
        })
    )
        .then(function (fileContents) {
            console.log('Compiling collected .st files');
            // import/compile content of .st files
            return Promise.all(
                fileContents.map(function (code) {
                    return new Promise(function (resolve, reject) {
                        var importer = configuration.globals.Importer._new();
                        try {
                            importer._import_(code._stream());
                            resolve(true);
                        } catch (ex) {
                            reject(Error("Compiler error in section:\n" +
                                    importer._lastSection() + "\n\n" +
                                    "while processing chunk:\n" +
                                    importer._lastChunk() + "\n\n" +
                                    (ex._messageText && ex._messageText() || ex.message || ex))
                            );
                        }
                    });
                })
            );
        })
        .then(function () {
            return configuration;
        });
}


/**
 * Export compiled categories to JavaScript files.
 * Returns a Promise() that resolves into the configuration object.
 */
function category_export(configuration) {
    return Promise.all(
        configuration.compile.map(function (stFile) {
            return new Promise(function (resolve, reject) {
                var category = path.basename(stFile, '.st');
                var jsFilePath = configuration.outputDir;
                if (jsFilePath == null) {
                    jsFilePath = path.dirname(stFile);
                }
                var jsFile = category + '.js';
                jsFile = path.join(jsFilePath, jsFile);
                configuration.compiled.push(jsFile);
                var smalltalkGlobals = configuration.globals;
                var packageObject = smalltalkGlobals.Package._named_(category);
                packageObject._transport()._namespace_(configuration.amdNamespace);
                fs.writeFile(jsFile, smalltalkGlobals.String._streamContents_(function (stream) {
                    smalltalkGlobals.AmdExporter._new()._exportPackage_on_(packageObject, stream);
                }), function (err) {
                    if (err)
                        reject(err);
                    else
                        resolve(true);
                });
            });
        })
    )
        .then(function () {
            return configuration;
        });
}


/**
 * Verify if all .st files have been compiled.
 * Returns a Promise() that resolves into the configuration object.
 */
function verify(configuration) {
    console.log('Verifying if all .st files were compiled');
    return Promise.all(
        configuration.compiled.map(function (file) {
            return new Promise(function (resolve, reject) {
                fs.exists(file, function (exists) {
                    if (exists)
                        resolve(true);
                    else
                        reject(Error('Compilation failed of: ' + file));
                });
            });
        })
    )
        .then(function () {
            return configuration;
        });
}


module.exports.Compiler = AmberCompiler;
module.exports.createDefaultConfiguration = createDefaultConfiguration;