var fs = require("fs");
var spawn = require("child_process").spawn;
var path = require("path");
var fileExtensionPattern;
var startChildProcess;
var noRestartOn = null;
var debug = true;
var verbose = false;
var restartVerbose = false;
var ignoredPaths = {};
var ignoreSymLinks = false;
var forceWatchFlag = false;
var instantKillFlag = false;
var timestampFlag = false;
var interactive = true;
var log = console.log;
var crash_queued = false;
var harmony_default_parameters = false;
var harmony_destructuring = false;

exports.run = run;

function run (args) {
    var arg, next, watch, ignore, pidFilePath, program, extensions, executor, poll_interval, debugFlag, debugBrkFlag, debugBrkFlagArg, harmony, inspect;
    while (arg = args.shift()) {
        if (arg === "--help" || arg === "-h" || arg === "-?") {
            return help();
        } else if (arg === "--quiet" || arg === "-q") {
            debug = false;
            log = function(){};
        } else if (arg === "--harmony") {
            harmony = true;
        } else if (arg === "--inspect") {
            inspect = true;
        } else if (arg === "--harmony_default_parameters") {
            harmony_default_parameters = true;
        } else if (arg === "--harmony_destructuring") {
            harmony_destructuring = true;
        } else if (arg === "--verbose" || arg === "-V") {
            verbose = true;
        } else if (arg === "--restart-verbose" || arg === "-RV") {
            restartVerbose = true;
        } else if (arg === "--watch" || arg === "-w") {
            watch = args.shift();
        } else if (arg == "--non-interactive" || arg === "-t") {
            interactive = false;
        } else if (arg === "--ignore" || arg === "-i") {
            ignore = args.shift();
        } else if (arg === "--save-pid" || arg === "-pid") {
            pidFilePath = args.shift();
        } else if (arg === "--ignore-symlinks") {
            ignoreSymLinks = true;
        } else if (arg === "--poll-interval" || arg === "-p") {
            poll_interval = parseInt(args.shift());
        } else if (arg === "--extensions" || arg === "-e") {
            extensions = args.shift();
        } else if (arg === "--exec" || arg === "-x") {
            executor = args.shift();
        } else if (arg === "--no-restart-on" || arg === "-n") {
            noRestartOn = args.shift();
        } else if (arg.indexOf("--debug") > -1 && arg.indexOf('--debug-brk') === -1) {
            debugFlag = arg;
        } else if (arg.indexOf('--debug-brk')>=0) {
            debugBrkFlag = true;
            debugBrkFlagArg = arg;
        } else if (arg === "--force-watch") {
            forceWatchFlag = true;
        } else if (arg === "--instant-kill" || arg === "-k") {
            instantKillFlag = true;
        } else if (arg === "--timestamp" || arg === "-s") {
            timestampFlag = true;
        } else if (arg === "--") {
            program = args;
            break;
        } else if (arg[0] != "-" && !args.length) {
            // Assume last arg is the program
            program = [arg];
        }
    }
    if (!program) {
        return help();
    }
    if (!watch) {
        watch = ".";
    }
    if (!poll_interval) {
        poll_interval = 1000;
    }

    var programExt = program.join(" ").match(/.*\.(\S*)/);
    programExt = programExt && programExt[1];

    if (!extensions) {
        // If no extensions passed try to guess from the program
        extensions = "node,js";
        if (programExt && extensions.indexOf(programExt) == -1) {
            // Support coffee and litcoffee extensions
            if(programExt === "coffee" || programExt === "litcoffee") {
                extensions += ",coffee,litcoffee";
            } else {
                extensions += "," + programExt;
            }
        }
    }
    fileExtensionPattern = new RegExp("^.*\.(" + extensions.replace(/,/g, "|") + ")$");

    if (!executor) {
        executor = (programExt === "coffee" || programExt === "litcoffee") ? "coffee" : "node";
    }

    if (debugFlag) {
        program.unshift(debugFlag);
    }
    if (debugBrkFlag) {
        program.unshift(debugBrkFlagArg);
    }
    if (harmony) {
        program.unshift("--harmony");
    }
    if (inspect) {
        program.unshift("--inspect");
    }
    if (harmony_default_parameters) {
        program.unshift("--harmony_default_parameters");
    }
    if (harmony_destructuring) {
        program.unshift("--harmony_destructuring");
    }
    if (executor === "coffee" && (debugFlag || debugBrkFlag)) {
        // coffee does not understand debug or debug-brk, make coffee pass options to node
        program.unshift("--nodejs")
    }
    if (pidFilePath) {
        var pid = process.pid;
        //
        // verify if we have write access
        //
        canWrite(pidFilePath, function(err) {
            if ( err ) {
                log("Continuing...");
            } else {
                fs.writeFileSync(pidFilePath, pid + '\n');
            }
        });
    }

    var deletePidFile = function(){
        fs.exists(pidFilePath, function (exists) {
            if ( exists ) {
                log("Removing pid file");
                fs.unlinkSync(pidFilePath);
            } else {
                log("No pid file to remove...");
            }
            process.exit();
        });
    };

    try {
        // Pass kill signals through to child
        [ "SIGTERM", "SIGINT", "SIGHUP", "SIGQUIT" ].forEach( function(signal) {
            process.on(signal, function () {
                var child = exports.child;
                if (child) {
                    log("Received "+signal+", killing child process...");
                    child.kill(signal);
                }
                if (pidFilePath){
                    deletePidFile();
                }
                else {
                    process.exit();
                }
            });
        });
    } catch(e) {
        // Windows doesn't support signals yet, so they simply don't get this handling.
        // https://github.com/joyent/node/issues/1553
    }

    process.on('exit', function () {
        var child = exports.child;
        if (child) {
            log("Parent process exiting, terminating child...");
            child.kill("SIGTERM");
        }
    });

    log("");
    log("Running node-supervisor with");
    log("  program '" + program.join(" ") + "'");
    log("  --watch '" + watch + "'");
    if (!interactive) {
        log("  --non-interactive");
    }
    if (ignore) {
        log("  --ignore '" + ignore + "'");
    }
    if (pidFilePath){
        log("  --save-pid '" + pidFilePath + "'");
    }
    log("  --extensions '" + extensions + "'");
    log("  --exec '" + executor + "'");
    log("");

    // store the call to startProgramm in startChildProcess
    // in order to call it later
    startChildProcess = function() { startProgram(program, executor); };

    // if we have a program, then run it, and restart when it crashes.
    // if we have a watch folder, then watch the folder for changes and restart the prog
    startChildProcess();

    // If interaction has not been disabled, start the CLI
    if(interactive) {

        //
        // Read input from stdin
        //
        var stdin = process.stdin;

        stdin.setEncoding( 'utf8' );
        stdin.on('readable', function() {
            var chunk = process.stdin.read();
            //
            // Restart process when user inputs rs
            //
            if (chunk !== null && chunk === "rs\n" || chunk === "rs\r\n") {
                //      process.stdout.write('data: ' + chunk);
                crash();
            }
        });
    }

    if (ignore) {
        var ignoreItems = ignore.split(',');
        ignoreItems.forEach(function (ignoreItem) {
            ignoreItem = path.resolve(ignoreItem);
            ignoredPaths[ignoreItem] = true;
            log("Ignoring directory '" + ignoreItem + "'.");
        });
    }

    var watchItems = watch.split(',');
    watchItems.forEach(function (watchItem) {
        watchItem = path.resolve(watchItem);

        if ( ! ignoredPaths[watchItem] ) {
            log("Watching directory '" + watchItem + "' for changes.");
            if(interactive) {
                log("Press rs for restarting the process.");
            }
            findAllWatchFiles(watchItem, function(f) {
                watchGivenFile( f, poll_interval );
            });
        }
    });
}

// function print (m, n) { console.log(m+(!n?"\n":"")); return print; }
function print (m) { console.log(m); return print; }

function help () {
    print
    ("")
    ("Node Supervisor is used to restart programs when they crash.")
    ("It can also be used to restart programs when a *.js file changes.")
    ("")
    ("Usage:")
    ("  supervisor [options] <program>")
    ("  supervisor [options] -- <program> [args ...]")
    ("")
    ("Required:")
    ("  <program>")
    ("    The program to run.")
    ("")
    ("Options:")
    ("  -w|--watch <watchItems>")
    ("    A comma-delimited list of folders or js files to watch for changes.")
    ("    When a change to a js file occurs, reload the program")
    ("    Default is '.'")
    ("")
    ("  -i|--ignore <ignoreItems>")
    ("    A comma-delimited list of folders to ignore for changes.")
    ("    No default")
    ("")
    ("  --ignore-symlinks")
    ("    Enable symbolic links ignoring when looking for files to watch.")
    ("")
    ("  -p|--poll-interval <milliseconds>")
    ("    How often to poll watched files for changes.")
    ("    Defaults to Node default.")
    ("")
    ("  -e|--extensions <extensions>")
    ("    Specific file extensions to watch in addition to defaults.")
    ("    Used when --watch option includes folders")
    ("    Default is 'node,js'")
    ("")
    ("  -x|--exec <executable>")
    ("    The executable that runs the specified program.")
    ("    Default is 'node'")
    ("")
    ("  --debug[=port]")
    ("    Start node with --debug flag. ")
    ("")
    ("  --debug-brk[=port]")
    ("    Start node with --debug-brk[=port] flag.")
    ("")
    ("  --harmony")
    ("    Start node with --harmony flag.")
    ("  --inspect")
    ("    Start node with --inspect flag.")
    ("")
    ("  --harmony_default_parameters")
    ("    Start node with --harmony_default_parameters flag.")
    ("")
    ("  -n|--no-restart-on error|exit")
    ("    Don't automatically restart the supervised program if it ends.")
    ("    Supervisor will wait for a change in the source files.")
    ("    If \"error\", an exit code of 0 will still restart.")
    ("    If \"exit\", no restart regardless of exit code.")
    ("    If \"success\", no restart only if exit code is 0.")
    ("")
    ("  -t|--non-interactive")
    ("    Disable interactive capacity.")
    ("    With this option, supervisor won't listen to stdin.")
    ("")
    ("  -k|--instant-kill")
    ("    use SIGKILL (-9) to terminate child instead of the more gentle SIGTERM.")
    ("")
    ("  --force-watch")
    ("    Use fs.watch instead of fs.watchFile.")
    ("    This may be useful if you see a high cpu load on a windows machine.")
    ("")
    ("  -s|--timestamp")
    ("    Log timestamp after each run.")
    ("    Make it easy to tell when the task last ran.")
    ("")
    ("  -h|--help|-?")
    ("    Display these usage instructions.")
    ("")
    ("  -q|--quiet")
    ("    Suppress DEBUG messages")
    ("")
    ("  -V|--verbose")
    ("    Show extra DEBUG messages")
    ("")
    ("Options available after start:")
    ("rs - restart process.")
    ("     Useful for restarting supervisor eaven if no file has changed.")
    ("")
    ("Examples:")
    ("  supervisor myapp.js")
    ("  supervisor myapp.coffee")
    ("  supervisor -w scripts -e myext -x myrunner myapp")
    ("  supervisor -- server.js -h host -p port")
    ("");
}

function startProgram (prog, exec) {
    log("Starting child process with '" + exec + " " + prog.join(" ") + "'");
    crash_queued = false;
    var child = exports.child = spawn(exec, prog, {stdio: 'inherit'});
    // Support for Windows ".cmd" files
    // On Windows 8.1, spawn can't launch apps without the .cmd extention
    // If already retried, let the app crash ... :'(
    if (process.platform === "win32" && exec.indexOf('.cmd') == -1) {
        child.on('error', function (err) {
            if (err.code === "ENOENT")
                return startProgram(prog, exec + ".cmd");
        });
    }
    if (child.stdout) {
        // node < 0.8 doesn't understand the 'inherit' option, so pass through manually
        child.stdout.addListener("data", function (chunk) { chunk && console.log(chunk); });
        child.stderr.addListener("data", function (chunk) { chunk && console.error(chunk); });
    }
    child.addListener("exit", function (code) {
        logTimestamp();

        if (!crash_queued) {
            log("Program " + exec + " " + prog.join(" ") + " exited with code " + code + "\n");
            exports.child = null;
            if (noRestartOn == "exit" || noRestartOn == "error" && code !== 0 || noRestartOn == "success" && code === 0) return;
        }
        startProgram(prog, exec);
    });
}

function logTimestamp() {
  if (timestampFlag) {
    // use console.log() directly rather than log() so that -q/--quiet
    // does not override/silence it
    console.log(Date().toString());
  }
}

function crash () {

    if (crash_queued)
        return;

    crash_queued = true;
    var child = exports.child;
    setTimeout(function() {
        if (child) {
            if (instantKillFlag) {
                log("crashing child with SIGKILL");
                process.kill(child.pid, "SIGKILL");
            } else {
                log("crashing child");
                process.kill(child.pid, "SIGTERM");
            }
        } else {
            log("restarting child");
            startChildProcess();
        }
    }, 50);
}

function crashWin (event, filename) {
    var shouldCrash = true;
    if( event === 'change' ) {
        if (filename) {
            filename = path.resolve(filename);
            Object.keys(ignoredPaths).forEach(function (ignorePath) {
                if ( filename.indexOf(ignorePath + '\\') === 0 || filename === ignorePath) {
                    shouldCrash = false;
                }
            });
        }
        if (shouldCrash) {
            if (verbose || restartVerbose) {
                log("Changes detected" + (filename ? ": " + filename : ""));
            }
            crash();
        }
    }
}
/**
 * Determine if a file can be written
 */
function canWrite(path, callback) {
    fs.open(path, "w", function (err, fd) {
        if (err) {
            if (err.code === "EISDIR") {
                log("Can't open " + path + ". It's a directory.");
            }
            if (err.code === "EACCESS") {
                log("Can't open " + path + ". No access.");
            } else {
                log("Can't open " + path + ".");
            }
            return callback(err);
        }
        fs.close(fd, function (err) {
            if (err) return callback(err);
            callback(null, true);
        });
    });
}


var nodeVersion = process.version.split(".");

var isWindowsWithoutWatchFile = process.platform === 'win32' && parseInt(nodeVersion[1]) <= 6;

function watchGivenFile (watch, poll_interval) {
    if (isWindowsWithoutWatchFile || forceWatchFlag) {
        fs.watch(watch, { persistent: true, interval: poll_interval }, crashWin);
    } else {
        fs.watchFile(watch, { persistent: true, interval: poll_interval }, function(oldStat, newStat) {
            // we only care about modification time, not access time.
            if ( newStat.mtime.getTime() !== oldStat.mtime.getTime() ) {
                if (verbose) {
                    log("file changed: " + watch);
                }
            }
            crash();
        });
    }
    if (verbose) {
        log("watching file '" + watch + "'");
    }
}

var findAllWatchFiles = function(dir, callback) {
    dir = path.resolve(dir);
    if (ignoredPaths[dir])
        return;
    fs[ignoreSymLinks ? 'lstat' : 'stat'](dir, function(err, stats) {
        if (err) {
            console.error('Error retrieving stats for file: ' + dir);
        } else {
            if (ignoreSymLinks && stats.isSymbolicLink()) {
                log("Ignoring symbolic link '" + dir + "'.");
                return;
            }

            if (stats.isDirectory()) {
                if (isWindowsWithoutWatchFile || forceWatchFlag) callback(dir);
                fs.readdir(dir, function(err, fileNames) {
                    if(err) {
                        console.error('Error reading path: ' + dir);
                    }
                    else {
                        fileNames.forEach(function (fileName) {
                            findAllWatchFiles(path.join(dir, fileName), callback);
                        });
                    }
                });
            } else {
                if ((!isWindowsWithoutWatchFile || !forceWatchFlag) && dir.match(fileExtensionPattern)) {
                    callback(dir);
                }
            }
        }
    });
};