#!/usr/bin/env node
/**
 * @fileoverview Implements the PCx86 command-line interface
 * @author <a href="mailto:Jeff@pcjs.org">Jeff Parsons</a>
 * @copyright © Jeff Parsons 2012-2017
 * @suppress {missingProperties}
 *
 * This file is part of PCjs, a computer emulation software project at <http://pcjs.org/>.
 *
 * PCjs is free software: you can redistribute it and/or modify it under the terms of the
 * GNU General Public License as published by the Free Software Foundation, either version 3
 * of the License, or (at your option) any later version.
 *
 * PCjs is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
 * even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with PCjs.  If not,
 * see <http://www.gnu.org/licenses/gpl.html>.
 *
 * You are required to include the above copyright notice in every modified copy of this work
 * and to display that copyright notice when the software starts running; see COPYRIGHT in
 * <http://pcjs.org/modules/shared/lib/defines.js>.
 *
 * Some PCjs files also attempt to load external resource files, such as character-image files,
 * ROM files, and disk image files. Those external resource files are not considered part of PCjs
 * for purposes of the GNU General Public License, and the author does not claim any copyright
 * as to their contents.
 */

"use strict";

var path = require("path");
var fs = require("fs");
var repl = require("repl");
var defines = require("../../shared/lib/defines");
var str = require("../../shared/lib/strlib");
var proc = require("../../shared/lib/proclib");

var fConsole = false;
var fDebug = false;
var args = proc.getArgs();
var argv = args.argv;
var sCmdPrev = "";
if (argv['console'] !== undefined) fConsole = argv['console'];
if (argv['debug'] !== undefined) fDebug = argv['debug'];

var lib = path.join(path.dirname(fs.realpathSync(__filename)), "../lib/");

try {
    var pkg = require(lib + "../../../package.json");
} catch(err) {
    console.log(err.message);
}

/*
 * We will build an array of components whose names will match the component names
 * used in a JSON machine definition file; eg:
 * 
 *  [
 *      {name: "chipset":
 *       Create: ChipSet,
 *       objects: []
 *      },
 *      ...
 *  ]
 *  
 * Every component name comes from the component filename, minus the ".js" extension;
 * Create is the constructor returned by require().
 * 
 * TODO: Update the list of ignored (ie, ignorable) components.
 */
var Component;
var dbg;
var aComponents = [];
var asComponentsIgnore = ["panel", "embed", "save"];

/*
 * A few of the components are subclasses of other classes (eg, "x86cpu" is a subclass
 * of "cpu").  In those situations, we "hoist" the subclass constructor into the 
 * corresponding superclass, because it is the name of the superclass that we rely on during
 * machine initialization.
 */
var aSubClasses = {
    "pcx86/lib/x86cpu": "pcx86/lib/cpu",
    "pcx86/lib/debugger": "shared/lib/debugger"
};
    
/**
 * loadComponents(asFiles)
 * 
 * @param {Array.<string>} asFiles
 */
function loadComponents(asFiles)
{
    for (var i = 0; i < asFiles.length; i++) {
        var sFile = asFiles[i];
        if (str.getExtension(sFile) != "js") continue;
        var sName = str.getBaseName(sFile, true);
        if (asComponentsIgnore.indexOf(sName) >= 0) continue;
        if (fDebug) console.log(sFile);
        try {
            /*
             * We COULD load ("require") all the files on-demand, because it's only the
             * browser initialization sequence we want to mimic in loadMachine(), but this
             * is simpler, and it also gives us direct references to certain components
             * we'll want to access later (eg, "component" in getComponentByType()).
             */
            var fn = require(lib + "../../../" + sFile);
            var sSuperClass = null;
            for (var s in aSubClasses) {
                if (sFile.indexOf(s) >= 0) {
                    sSuperClass = aSubClasses[s];
                    break;
                }
            }
            if (sSuperClass) {
                for (var j = 0; j < aComponents.length; j++) {
                    if (aComponents[j].path.indexOf(sSuperClass) >= 0) {
                        if (fDebug) console.log("updating superclass " + aComponents[j].path + " with subclass " + sFile);
                        aComponents[j].Create = fn;
                        sName = null;
                        break;
                    }
                }
            }
            if (sName == "component") {
                fn.log = fn.println = function(s, type) {
                    console.log((type !== undefined? (type + ": ") : "") + (s || ""));
                };      // jshint ignore:line
            }
            if (sName) {
                aComponents.push({name: sName, path: sFile, Create: fn, objects: []});
            }
            if (sName == "defines") {
                /*
                 * Enabling component console messages requires setting CONSOLE to true.
                 */ 
                if (global.DEBUG !== undefined) {
                    global.DEBUG = fDebug;
                    global.CONSOLE = fConsole;
                }
            }
        } catch(err) {
            console.log(err.message);
        }
    }
}

/**
 * getComponentByName(sName)
 * 
 * @param sName
 * @return {*}
 */
function getComponentByName(sName)
{
    for (var i = 0; i < aComponents.length; i++) {
        if (aComponents[i].name == sName) {
            return aComponents[i].Create;
        }
    }
    return null;
}

/**
 * getComponentByType(sType)
 *
 * @param sType
 * @return {*}
 */
function getComponentByType(sType)
{
    var component = null;
    
    if (!Component) {
        Component = getComponentByName("component");
    }
    if (Component) {
        component = Component.getComponentByType(sType);
    }
    return component;
}

/**
 * loadMachine(sFile)
 * 
 * @param {string} sFile
 * @return {Object} representing the machine whose component objects have been loaded into aComponents
 */
function loadMachine(sFile)
{
    if (fDebug) console.log('loadMachine("' + sFile + '")');
    
    /*
     * Clear any/all saved objects from any previous machine
     */
    var i, j;
    Component = dbg = null;
    for (i = 0; i < aComponents.length; i++) {
        aComponents[i].objects = [];
    }
    
    var machine;
    try {
        /*
         * Since our JSON files may contain comments, hex values, and/or other tokens deemed
         * unacceptable by the JSON Overlords, we can't use require() to load it, as we're able to
         * do with "package.json".  Also note that require() assumes the same path as that of the
         * requiring file, whereas fs.readFileSync() assumes the path reported by process.cwd().
         * 
         * TODO: I've since removed the comments from my sample "ibm5150.json" file, so we could
         * try to reinstate this code; however, there are still hex constants, which I find *much*
         * preferable to the decimal equivalents.  JSON's restrictions continue to irritate me.
         *
         *      var machine = require(lib + "../bin/" +sFile);
         */
        var sMachine = fs.readFileSync(sFile, {encoding: "utf8"});
        sMachine = '(' + sMachine + ')';
        if (fDebug) console.log(sMachine);
        machine = eval(sMachine);       // jshint ignore:line
        if (machine) {
            /*
             * Since we have a machine object, we now mimic the initialization sequence that occurs
             * in the browser, by walking the list of PCx86 components we loaded above and looking for
             * matches.
             */
            var idMachine = "";
            
            /*
             * 'machine' is a pseudo-component that is only used to define an ID for the entire machine;
             * if it exists, then that ID is prepended to every component ID, just as our XSLT code would
             * do for a machine XML file.  This relieves the JSON file from having to manually prepend
             * a machine ID to every component ID itself.
             * 
             * This doesn't mean I anticipate a Node environment running multiple machines, as we do in
             * a browser; it only means that I'm trying to make both environments operate similarly.
             */
            if (machine['machine']) {
                idMachine = machine['machine']['id'];
            }
            
            for (i = 0; i < aComponents.length; i++) {
                
                var component = aComponents[i];
                var parms = machine[component.name];
                /*
                 * If parms is undefined, it means there is no component with that name defined in the
                 * machine object (NOT that the component has no parms), and therefore we should skip it.
                 */
                if (parms === undefined) continue;
                /*
                 * If parms is an Array, then we must create an object for each parms element; and yes,
                 * I'm relying on the fact that none of my parm objects use a "length" property, as a quick
                 * and dirty way of differentiating objects from arrays.
                 */
                var aParms = parms.length !== undefined? parms : [parms];
                for (j = 0; j < aParms.length; j++) {
                    
                    var obj;
                    var parmsObj = aParms[j];
                    if (idMachine) parmsObj['id'] = idMachine + '.' + parmsObj['id'];
                    
                    if (fDebug) {
                        console.log("creating " + component.name + "...");
                        console.log(parmsObj);
                    }
                    
                    if (component.name == "cpu") {
                        parmsObj['autoStart'] = false;
                    }
                    
                    try {
                        obj = new component.Create(parmsObj);
                    } catch(err) {
                        console.log("error creating " + component.name + ": " + err.message);
                        continue;
                    }
                    
                    console.log(obj['id'] + " object created");
                    component.objects.push(obj);
                    
                    if (obj.type == "Debugger") {
                        dbg = obj;
                    }
                }
            }
            /*
             * Return the original machine object only in DEBUG mode
             */
            if (!fDebug) machine = true;
        }
    } catch(err) {
        console.log(err.message);
    }
    return machine;
}

/**
 * doCommand(sCmd)
 * 
 * @param {string} sCmd
 * @return {*}
 */
function doCommand(sCmd)
{
    if (!sCmd) {
        sCmd = sCmdPrev;
    } else {
        sCmdPrev = sCmd;
    }
    
    var result = false;
    var aTokens = sCmd.split(' ');
    
    switch(aTokens[0]) {
    case "cwd":
        result = process.cwd();
        break;
    case "load":
        result = loadMachine(aTokens[1]);
        break;
    case "quit":
        process.exit();
        result = true;
        break;
    default:
        if (sCmd) {
            try {
                if (dbg && !dbg.doCommands(sCmd, true)) {
                    sCmd = '(' + sCmd + ')';
                    result = eval(sCmd);        // jshint ignore:line
                }
            } catch(err) {
                console.log(err.message);
            }
        }
        break;
    }
    return result;
}

/**
 * onCommand(cmd, context, filename, callback)
 * 
 * The Node docs (http://nodejs.org/api/repl.html) say that repl.start's "eval" option is:
 * 
 *      a function that will be used to eval each given line; defaults to an async wrapper for eval()
 *      
 * and it gives this example of such a function:
 * 
 *      function eval(cmd, context, filename, callback) {
 *          callback(null, result);
 *      }
 *      
 * but it defines NEITHER the parameters for the function NOR the parameters for the callback().
 * 
 * It's pretty clear that "result" is expected to return whatever "eval()" would return for the expression
 * in "cmd" (which is always parenthesized in preparation for a call to "eval()"), but it's not clear what
 * the first callback() parameter (represented by null) is supposed to be.  Should we assume it's an Error
 * object, in case we want to report an error?
 * 
 * @param {string} cmd
 * @param {Object} context
 * @param {string} filename
 * @param {function(Object|null, Object)} callback
 */
var onCommand = function (cmd, context, filename, callback)
{
    var result = false;
    /*
     * WARNING: After updating from Node v0.10.x to v0.11.x, the incoming expression in "cmd" is no longer
     * parenthesized, so I had to tweak the RegExp below.  But... WTF.  Do we not care what we break, folks?
     */
    var match = cmd.match(/^\(?\s*(.*?)\s*\)?$/);
    if (match) result = doCommand(match[1]);
    callback(null, result);
};

if (pkg) {
    loadComponents(pkg.pcX86Files);
}

/*
 * Before falling into the REPL, process any command-line (--cmd) commands -- which should eventually include batch files.
 */
if (argv['cmd'] !== undefined) {
    var cmds = argv['cmd'];
    var aCmds = (typeof cmds == "string"? [cmds] : cmds);
    for (var i = 0; i < aCmds.length; i++) {
        doCommand(aCmds[i]);
    }
    sCmdPrev = "";
}

repl.start({
    prompt: "PCx86> ",
    input: process.stdin,
    output: process.stdout,
    eval: onCommand 
});