Query Composer to determine global config dir

Composer has a decent chunk of logic for deciding which directory to use
as the global config dir. Rather than mirror that logic in shell scripts,
I've updated the hooks to use `composer config --global home` to
determine the config dir.

Running `composer config --global home` on my machine takes around 100ms
on average, so I've also updated the install instructions to generate a
fixed path for `source`'ing (sluggish shell profiles are a pain). The
config dir is also queried on the first completion attempt. I've done
this instead of adding an environment variable to the profile, as this
implementation is backwards compatible with existing installs.

Fixes #10

Author: stecman

README.md

@@ -6,21 +6,24 @@ This is an experimental hack to add [Symfony BASH auto complete](https://github.
 
 ## Installation
 
-1. Run `composer global require stecman/composer-bash-completion-plugin dev-master`
-2. Add a completion hook to your shell's user config file:
-  - If you're using BASH, put the following in your `~/.bash_profile` file:
-
-    ```bash
-    # Add shell auto-completion for composer
-    source "${COMPOSER_HOME-$HOME/.composer}/vendor/stecman/composer-bash-completion-plugin/hooks/bash-completion"
-    ```
-  - If you're using ZSH, put the following in your `~/.zshrc` file:
-    
-    ```bash
-    # Add shell auto-completion for composer
-    source "${COMPOSER_HOME-$HOME/.composer}/vendor/stecman/composer-bash-completion-plugin/hooks/zsh-completion"
-    ```
-3. Reload the modified shell config (or open a new shell), and enjoy tab completion on Composer
+1. Install the plugin:
+
+  ```
+  composer global require stecman/composer-bash-completion-plugin dev-master
+  ```
+
+2. Generate code to register a completion hook for your shell and Composer configuration:
+
+  ```
+  source $(composer config home --global)/vendor/stecman/composer-bash-completion-plugin/generate-hook
+  ```
+
+3. Add the registration code to your shell profile:
+
+  - If you're using BASH, copy the output to your `~/.bash_profile`
+  - If you're using ZSH, copy the output to your `~/.zshrc`
+
+4. Reload your modified shell config (or open a new shell), and enjoy tab completion on Composer
 
 ## Explanation
 

generate-hook

@@ -0,0 +1,15 @@
+# Generate registration code to go in a shell profile
+
+_composercomplete_hook_dir="$(composer config home --global)/vendor/stecman/composer-bash-completion-plugin/hooks"
+
+echo "# Add tab auto-completion for composer"
+
+if [ ! -z $BASH_VERSION ]; then
+	echo "source $_composercomplete_hook_dir/bash-completion"
+fi
+
+if [ ! -z $ZSH_VERSION ]; then
+	echo "source $_composercomplete_hook_dir/zsh-completion"
+fi
+
+unset _composercomplete_hook_dir

hooks/bash-completion

@@ -8,15 +8,13 @@ function _composercomplete {
 
     export CMDLINE_CONTENTS CMDLINE_CURSOR_INDEX CMDLINE_WORDBREAKS
 
-    # Honour the COMPOSER_HOME variable if set
-    local composer_dir=$COMPOSER_HOME
-    if [ -z "$composer_dir" ]; then
-        composer_dir=$HOME/.composer
+    # Query and cache where the global composer.json lives
+    if [ -z "$_composer_config_dir" ]; then
+        _composer_config_dir="$(composer config home --global)"
     fi
 
     local RESULT STATUS;
-
-    RESULT=$(cd $composer_dir && composer depends _completion);
+    RESULT=$(cd "$_composer_config_dir" && composer depends _completion);
     STATUS=$?;
 
     local cur;
@@ -32,4 +30,4 @@ function _composercomplete {
     __ltrim_colon_completions "$cur";
 };
 
-complete -F _composercomplete composer;
+complete -F _composercomplete composer;

hooks/zsh-completion

@@ -6,14 +6,13 @@ function _composer {
     local -x CMDLINE_CURSOR_INDEX
     (( CMDLINE_CURSOR_INDEX = ${#${(j. .)words[1,CURRENT]}} ))
 
-    # Honour the COMPOSER_HOME variable if set
-    local composer_dir=$COMPOSER_HOME
-    if [ -z "$composer_dir" ]; then
-        composer_dir=$HOME/.composer
+    # Query and cache where the global composer.json lives
+    if [ -z "$_composer_config_dir" ]; then
+        _composer_config_dir="$(composer config home --global)"
     fi
 
     local RESULT STATUS
-    RESULT=("${(@f)$( cd $composer_dir && composer depends _completion )}")
+    RESULT=("${(@f)$( cd $_composer_config_dir && composer depends _completion )}")
     STATUS=$?;
 
     if [ $STATUS -ne 0 ]; then
@@ -24,4 +23,4 @@ function _composer {
     compadd -- $RESULT
 };
 
-compdef _composer composer;
+compdef _composer composer;