add install/uninstall helper

* install add the completer script to the according shell config file only
if not present yet.
* uninstall removes the completer script from the bashrc/zshrc file.

process.env.SHELL is used to know which file to read/write. Basically, just
helpers that does the same as completer completion >> ~/.bashrc

bin/cake-complete

@@ -28,6 +28,12 @@ console.log([
   '» You may want to setup the completion in your ~/.bashrc or ~/.zshrc file, if not already.',
   '',
   '   cake-complete completion >> ~/.bashrc',
-  'Or',
-  '   cake-complete completion >> ~/.zshrc'
+  'Or, using zsh:',
+  '   cake-complete completion >> ~/.zshrc',
+  '',
+  'Or you may use the install command:',
+  '   cake-complete completion install',
+  '',
+  'Simply run this command to uninstall',
+  '   cake-complete completion uninstall'
 ].join('\n'));

bin/play-complete

@@ -27,5 +27,11 @@ console.log([
   '',
   '   play-complete completion >> ~/.bashrc',
   'Or',
-  '   play-complete completion >> ~/.zshrc'
+  '   play-complete completion >> ~/.zshrc',
+  '',
+  'Or you may use the install command:',
+  '   play-complete completion install',
+  '',
+  'Simply run this command to uninstall',
+  '   play-complete completion uninstall'
 ].join('\n'));

bin/rake-complete

@@ -44,5 +44,11 @@ console.log([
   '',
   '   rake-complete completion >> ~/.bashrc',
   'Or',
-  '   rake-complete completion >> ~/.zshrc'
+  '   rake-complete completion >> ~/.zshrc',
+  '',
+  'Or you may use the install command:',
+  '   rake-complete completion install',
+  '',
+  'Simply run this command to uninstall',
+  '   rake-complete completion uninstall'
 ].join('\n'));

lib/completion.js

@@ -1,6 +1,7 @@
 
 var fs = require('fs'),
   path = require('path'),
+  exec = require('child_process').exec,
   args = process.argv.slice(2),
   completeCmd = args[0] === 'completion',
   installCmd = completeCmd && args[1] === 'install',
@@ -28,8 +29,17 @@ exports.complete = function complete(name, completer, cb) {
   // if not a complete command, return here.
   if(!completeCmd) return cb();
 
+  // if install cmd, add complete script to either ~/.bashrc or ~/.zshrc
+  if(installCmd) return install(name + '', completer, console.log.bind(console));
+
+  // if install cmd, add complete script to either ~/.bashrc or ~/.zshrc
+  if(uninstallCmd) return uninstall(name, completer, console.log.bind(console));
+
   // if the COMP_* are not in the env, then dump the install script.
-  if(!words || !point || !line) return script(name, completer, cb);
+  if(!words || !point || !line) return script(name, completer, function(err, content) {
+    if(err) return cb(err);
+    console.log(content);
+  });
 
   var partial = line.substr(0, point),
   last = line.split(' ').slice(-1).join(''),
@@ -95,16 +105,78 @@ function abbrev(o) { return function(it) {
 // output the completion.sh script to the console for install instructions.
 // This is actually a 'template' where the package name is used to setup
 // the completion on the right command, and properly name the bash/zsh functions.
-function script (name, completer, cb) {
+function script(name, completer, cb) {
   var p = path.resolve(__dirname, 'completion/completion.sh');
 
   fs.readFile(p, 'utf8', function (er, d) {
     if (er) return cb(er);
     d = d
       .replace(/\{pkgname\}/g, name)
       .replace(/{completer}/g, completer);
-    console.log(d);
-    cb();
+    cb(null, d);
+  });
+}
+
+function install(name, completer, cb) {
+  console.log('Installing completion for ', name, ' using ', completer);
+  var markerIn = '###-begin-' + name + '-completion-###',
+    markerOut = '###-end-' + name + '-completion-###';
+
+  installed(markerIn, completer, function(isInstalled) {
+    if(isInstalled) {
+      return cb(' ✗ ', completer, 'has been already installed. Do nothing.');
+    }
+
+    // probably, will prompt user for installation here (y/n)
+    exec(completer + ' completion >> ~/.' + process.env.SHELL.match(/\/bin\/(\w+)/)[1] + 'rc', function(err) {
+      if(err) return cb(err);
+      return cb(' ✓ ', completer, 'installed.');
+    });
   });
 }
 
+function uninstall(name, completer, cb) {
+  console.log('Uninstalling completion for ', name);
+
+  var markerIn = '###-begin-' + name + '-completion-###',
+    markerOut = '###-end-' + name + '-completion-###';
+
+  readRc(completer, function(err, file) {
+    if(err) return cb(err);
+
+    var part = file.split(markerIn)[1];
+    if(!part) return cb(' ✗ ', completer, 'does not appear in your .zshrc or .bashrc file. Do nothing.');
+
+    part = markerIn + part.split(markerOut)[0] + markerOut;
+    writeRc(file.replace(part, ''), function(err) {
+      if(err) return cb(err);
+      return cb(' ✓ ', completer, 'uninstalled.');
+    });
+  });
+}
+
+function readRc(completer, cb) {
+  var file = '.' + process.env.SHELL.match(/\/bin\/(\w+)/)[1] + 'rc',
+    filepath = path.join(process.env.HOME, file);
+  path.exists(filepath, function (state) {
+    if(!state) return cb(new Error("No " + file + " file. You'll have to run instead: " + completer + " completion >> ~/" + file));
+    fs.readFile(filepath, 'utf8', cb);
+  });
+}
+
+function writeRc(content, cb) {
+  var file = '.' + process.env.SHELL.match(/\/bin\/(\w+)/)[1] + 'rc',
+    filepath = path.join(process.env.HOME, file);
+  path.exists(filepath, function (state) {
+    if(!state) return cb(new Error("No " + file + " file. You'll have to run instead: " + completer + " completion >> ~/" + file));
+    fs.writeFile(filepath, content, cb);
+  });
+}
+
+function installed (marker, completer, cb) {
+  readRc(completer, function(err, file) {
+    if(err) return cb(err);
+    var installed = file.match(marker);
+    return cb(!!installed);
+  });
+}