<?php namespace Illuminate\Config;

use Illuminate\Filesystem\Filesystem;

class FileLoader implements LoaderInterface {

	/**
	 * The filesystem instance.
	 *
	 * @var \Illuminate\Filesystem\Filesystem
	 */
	protected $files;

	/**
	 * The default configuration path.
	 *
	 * @var string
	 */
	protected $defaultPath;

	/**
	 * All of the named path hints.
	 *
	 * @var array
	 */
	protected $hints = array();

	/**
	 * A cache of whether namespaces and groups exists.
	 *
	 * @var array
	 */
	protected $exists = array();

	/**
	 * Create a new file configuration loader.
	 *
	 * @param  \Illuminate\Filesystem\Filesystem  $files
	 * @param  string  $defaultPath
	 * @return void
	 */
	public function __construct(Filesystem $files, $defaultPath)
	{
		$this->files = $files;
		$this->defaultPath = $defaultPath;
	}

	/**
	 * Load the given configuration group.
	 *
	 * @param  string  $environment
	 * @param  string  $group
	 * @param  string  $namespace
	 * @return array
	 */
	public function load($environment, $group, $namespace = null)
	{
		$items = array();

		// First we'll get the root configuration path for the environment which is
		// where all of the configuration files live for that namespace, as well
		// as any environment folders with their specific configuration items.
		$path = $this->getPath($namespace);

		if (is_null($path))
		{
			return $items;
		}

		// First we'll get the main configuration file for the groups. Once we have
		// that we can check for any environment specific files, which will get
		// merged on top of the main arrays to make the environments cascade.
		$file = "{$path}/{$group}.php";

		if ($this->files->exists($file))
		{
			$items = $this->getRequire($file);
		}

		// Finally we're ready to check for the environment specific configuration
		// file which will be merged on top of the main arrays so that they get
		// precedence over them if we are currently in an environments setup.
		$file = "{$path}/{$environment}/{$group}.php";

		if ($this->files->exists($file))
		{
			$items = $this->mergeEnvironment($items, $file);
		}

		return $items;
	}

	/**
	 * Merge the items in the given file into the items.
	 *
	 * @param  array   $items
	 * @param  string  $file
	 * @return array
	 */
	protected function mergeEnvironment(array $items, $file)
	{
		return array_replace_recursive($items, $this->getRequire($file));
	}

	/**
	 * Determine if the given group exists.
	 *
	 * @param  string  $group
	 * @param  string  $namespace
	 * @return bool
	 */
	public function exists($group, $namespace = null)
	{
		$key = $group.$namespace;

		// We'll first check to see if we have determined if this namespace and
		// group combination have been checked before. If they have, we will
		// just return the cached result so we don't have to hit the disk.
		if (isset($this->exists[$key]))
		{
			return $this->exists[$key];
		}

		$path = $this->getPath($namespace);

		// To check if a group exists, we will simply get the path based on the
		// namespace, and then check to see if this files exists within that
		// namespace. False is returned if no path exists for a namespace.
		if (is_null($path))
		{
			return $this->exists[$key] = false;
		}

		$file = "{$path}/{$group}.php";

		// Finally, we can simply check if this file exists. We will also cache
		// the value in an array so we don't have to go through this process
		// again on subsequent checks for the existing of the config file.
		$exists = $this->files->exists($file);

		return $this->exists[$key] = $exists;
	}

	/**
	 * Apply any cascades to an array of package options.
	 *
	 * @param  string  $env
	 * @param  string  $package
	 * @param  string  $group
	 * @param  array   $items
	 * @return array
	 */
	public function cascadePackage($env, $package, $group, $items)
	{
		// First we will look for a configuration file in the packages configuration
		// folder. If it exists, we will load it and merge it with these original
		// options so that we will easily "cascade" a package's configurations.
		$file = "packages/{$package}/{$group}.php";

		if ($this->files->exists($path = $this->defaultPath.'/'.$file))
		{
			$items = array_merge(
				$items, $this->getRequire($path)
			);
		}

		// Once we have merged the regular package configuration we need to look for
		// an environment specific configuration file. If one exists, we will get
		// the contents and merge them on top of this array of options we have.
		$path = $this->getPackagePath($env, $package, $group);

		if ($this->files->exists($path))
		{
			$items = array_merge(
				$items, $this->getRequire($path)
			);
		}

		return $items;
	}

	/**
	 * Get the package path for an environment and group.
	 *
	 * @param  string  $env
	 * @param  string  $package
	 * @param  string  $group
	 * @return string
	 */
	protected function getPackagePath($env, $package, $group)
	{
		$file = "packages/{$package}/{$env}/{$group}.php";

		return $this->defaultPath.'/'.$file;
	}

	/**
	 * Get the configuration path for a namespace.
	 *
	 * @param  string  $namespace
	 * @return string
	 */
	protected function getPath($namespace)
	{
		if (is_null($namespace))
		{
			return $this->defaultPath;
		}
		elseif (isset($this->hints[$namespace]))
		{
			return $this->hints[$namespace];
		}
	}

	/**
	 * Add a new namespace to the loader.
	 *
	 * @param  string  $namespace
	 * @param  string  $hint
	 * @return void
	 */
	public function addNamespace($namespace, $hint)
	{
		$this->hints[$namespace] = $hint;
	}

	/**
	 * Returns all registered namespaces with the config
	 * loader.
	 *
	 * @return array
	 */
	public function getNamespaces()
	{
		return $this->hints;
	}

	/**
	 * Get a file's contents by requiring it.
	 *
	 * @param  string  $path
	 * @return mixed
	 */
	protected function getRequire($path)
	{
		return $this->files->getRequire($path);
	}

	/**
	 * Get the Filesystem instance.
	 *
	 * @return \Illuminate\Filesystem\Filesystem
	 */
	public function getFilesystem()
	{
		return $this->files;
	}

}
