terminal.js

var sys = require('util');

// Terminal object
// Allows for controlling the terminal by outputting control characters
var terminal = {
    // Terminal escape character
    escape_code: '\033',

    // Display attributes reset
    reset_code: '\033[0m',

    // Terminal display colors
    color_codes: {
        foreground: {
            'black':      30,
            'red':        31,
            'green':      32,
            'yellow':     33,
            'blue':       34,
            'magenta':    35,
            'purple':     35,
            'cyan':       36,
            'white':      37
        },
        background: {
            'black':      40,
            'red':        41,
            'green':      42,
            'yellow':     43,
            'blue':       44,
            'magenta':    45,
            'cyan':       46,
            'white':      47
        },
        attribute: {
            'reset':      0,
            'bright':     1,
            'bold':       1,
            'dim':        2,
            'underscore': 4,
            'underline':  4,
            'blink':      5,
            'inverse':    6,
            'hidden':     8
        }
    },

    // Get the terminal command for a color. A color command is build up of a
    // foreground, a background and a display attribute. These can be defined as
    // an object resulting in a compound command. When the color is passed as a
    // string it is assumed this is a foreground color.
    _color: function(color) {
        if (undefined === color) {
            throw 'Color not defined';
        }

        // Check if color is only a string
        if (typeof color == 'string') {
            // Assume we want a foreground color
            color = {foreground: color};
        }

        // Collect all parts of the color code
        var code = [];
        for (type in color) {
            var colorCode = this._colorCode(color[type], type);
            if (null !== colorCode) {
                code.push(colorCode);
            }
        }

        // Construct the complete code
        return this.escape_code + '[' + code.join(';') + 'm';
    },

    // Print a terminal color command. This uses the `_color` function to
    // retreive the color command.
    color: function(color) {
        process.stdout.write(this._color(color));
        return this;
    },

    // Print the color reset code.
    reset: function() {
        process.stdout.write(this.reset_code);
        return this;
    },

    // Get a color code for a color type. Color types are `foreground`,
    // `background` or `attribute`.
    _colorCode: function(name, type) {
        type = type || 'foreground';

        if (type in this.color_codes) {
            if (name in this.color_codes[type]) {
                return this.color_codes[type][name];
            }
        }

        return null;
    },

    // Colorize a message and return it. The message can be colorized with
    // modifiers that are preceded by a `%` character. The following modifiers
    // are supported:
    //                  text      text            background
    //      ------------------------------------------------
    //      %k %K %0    black     dark grey       black
    //      %r %R %1    red       bold red        red
    //      %g %G %2    green     bold green      green
    //      %y %Y %3    yellow    bold yellow     yellow
    //      %b %B %4    blue      bold blue       blue
    //      %m %M %5    magenta   bold magenta    magenta
    //      %p %P       magenta (think: purple)
    //      %c %C %6    cyan      bold cyan       cyan
    //      %w %W %7    white     bold white      white
    //
    //      %F     Blinking, Flashing
    //      %U     Underline
    //      %8     Reverse
    //      %_,%9  Bold
    //
    //      %n,%N  Resets the color
    //      %%     A single %
    _colorize: function(message) {
        var conversions = {
            '%y': {foreground: 'yellow'},
            '%g': {foreground: 'green'},
            '%b': {foreground: 'blue'},
            '%r': {foreground: 'red'},
            '%p': {foreground: 'magenta'},
            '%m': {foreground: 'magenta'},
            '%c': {foreground: 'cyan'},
            '%w': {foreground: 'grey'},
            '%k': {foreground: 'black'},
            '%n': 'reset',
            '%Y': {foreground: 'yellow',  attribute: 'bold'},
            '%G': {foreground: 'green',   attribute: 'bold'},
            '%B': {foreground: 'blue',    attribute: 'bold'},
            '%R': {foreground: 'red',     attribute: 'bold'},
            '%P': {foreground: 'magenta', attribute: 'bold'},
            '%M': {foreground: 'magenta', attribute: 'bold'},
            '%C': {foreground: 'cyan',    attribute: 'bold'},
            '%W': {foreground: 'grey',    attribute: 'bold'},
            '%K': {foreground: 'black',   attribute: 'bold'},
            '%N': 'reset',
            '%0': {background: 'black'},
            '%1': {background: 'red'},
            '%2': {background: 'green'},
            '%3': {background: 'yellow'},
            '%4': {background: 'blue'},
            '%5': {background: 'magenta'},
            '%6': {background: 'cyan'},
            '%7': {background: 'grey'},
            '%F': {attribute: 'blink'},
            '%U': {attribute: 'underline'},
            '%8': {attribute: 'inverse'},
            '%9': {attribute: 'bold'},
            '%_': {attribute: 'bold'}
        };

        // Replace escaped '%' characters
        message = message.replace('%%', '% ');

        // Convert all tokens with color codes
        for (conversion in conversions) {
            // Special case for `reset`
            if ('reset' === conversions[conversion]) {
                message = message.replace(conversion, this.reset_code);
            } else {
                message = message.replace(new RegExp(conversion, ['g']), this._color(conversions[conversion]));
            }
        }
        // Reset all escape '%' characters
        message = message.replace('% ', '%');

        // Return the message
        return message;
    },

    // This uses the `_colorize` function to __print__ a colorized message.
    colorize: function(message) {
        process.stdout.write(this._colorize(message));
        return this;
    },

    // Write a message in the terminal
    write: function(message) {
        process.stdout.write(message);
        return this;
    },

    // Print one or more new line characters
    nl: function(n) {
        n = n || 1;
        for (var i = 0; i < n; i++) {
            process.stdout.write('\n');
        }
        return this;
    },

    // Move the terminal cursor
    move: function(x, y) {
        x = x || 0;
        y = y || 0;

        var command = this.escape_code + '[';
        if (undefined !== x && 0 < x) {
            command += ++x;
        }
        if (undefined !== y && 0 < y) {
            command += ';' + ++y ;
        }

        process.stdout.write(command + 'H');
        return this;
    },

    // Move the terminal cursor up `x` positions
    up: function(x) {
        process.stdout.write(this.escape_code + '[' + x + 'A');
        return this;
    },

    // Move the terminal cursor down x positions
    down: function(x) {
        process.stdout.write(this.escape_code + '[' + x + 'B');
        return this;
    },

    // Move the terminal cursor `p` positions right
    right: function(p) {
        process.stdout.write(this.escape_code + '[' + p + 'C');
        return this;
    },

    // Move the terminal cursor `p` positions left
    left: function(p) {
        process.stdout.write(this.escape_code + '[' + p + 'D');
        return this;
    },

    // Clear all characters from the terminal screen
    clear: function() {
        process.stdout.write(this.escape_code + '[2J');
        return this;
    },

    // Clear the line the cursor is at
    clearLine: function() {
        process.stdout.write(this.escape_code + '[2K');
        return this;
    },

    // Clear the next `n` characters from the current cursor position.
    clearCharacters: function(n) {
        this.write(new Array(n + 2).join(' ')).left(n + 2);
        return this;
    }
};

// Export the command object
module.exports = terminal;