feat: add command-line interface

closes #1

.npmignore

@@ -0,0 +1,2 @@
+demo/
+test/

README.md

@@ -21,12 +21,34 @@ Returns an array of suggestions, sorted by difference from the target color.
 Example of suggesting LESS functions:
 
     > cuttle.suggest("#000", "#333");
-    
+
     [ { difference: 0, format: "lighten(@input, 20%)" } ]
-    
+
 Example of suggesting SASS functions:
-    
+
     > cuttle.suggest("#ae465f", "#aeae46", "sass");
-
+
+    [ { difference: 0.4477, format: "adjust-hue($input, 75)" } ]
+
+
+## CLI Usage
+
+Install as a global module through `npm install -g cuttle`. Then get suggestions by running
+
+    $ cuttle --from #ae465f --to #aeae46 --dialect sass
+
     [ { difference: 0.4477, format: "adjust-hue($input, 75)" } ]
 
+Full usage options:
+
+    Usage: cuttle [options]
+
+    Suggests transition functions between colors
+
+    Options:
+
+      -h, --help               output usage information
+      -V, --version            output the version number
+      -f, --from <color>       input color (e.g. #ae465f)
+      -t, --to <color>         output color (e.g. #aeae46)
+      -d, --dialect <dialect>  dialect of output, either "sass" or "less"

bin/cuttle.js

@@ -0,0 +1,34 @@
+#!/usr/bin/env node
+
+var program = require('commander');
+var package = require('../package.json');
+var suggest = require('../lib/main').suggest;
+
+var color = /^(#?[0-9a-f]{3,6})$/i;
+
+program
+  .version(package.version)
+  .description('Suggests transition functions between colors')
+  .option('-f, --from <color>', 'input color (e.g. #ae465f)', color)
+  .option('-t, --to <color>', 'output color (e.g. #aeae46)', color)
+  .option('-d, --dialect <dialect>', 'dialect of output (either "sass" or "less")', /^(sass|less)$/i, 'less')
+  .parse(process.argv);
+
+if (!color.test(program.from) || !color.test(program.to)) {
+    console.error('Both --from and --to colors must be specified to suggest a transition!');
+
+    program.outputHelp();
+
+    process.exit(1);
+}
+
+var convertSuggestion = function(s) {
+    return {
+        difference: s.difference,
+        format: s.format
+    };
+}
+
+var suggestions = suggest(program.from, program.to, program.dialect).map(convertSuggestion);
+
+console.log(suggestions);

package.json

@@ -3,6 +3,9 @@
   "version": "0.0.0",
   "description": "Determine color function based on color examples",
   "main": "lib/main.js",
+  "bin": {
+    "cuttle": "bin/cuttle.js"
+  },
   "scripts": {
     "test": "grunt test"
   },
@@ -30,7 +33,8 @@
     "mocha": "~2.2.5"
   },
   "dependencies": {
-    "less": "~2.5.1",
-    "chroma-js": "~1.0.1"
+    "chroma-js": "~1.0.1",
+    "commander": "^2.9.0",
+    "less": "~2.5.1"
   }
 }