<?php

namespace SilverStripe\View;

use SilverStripe\Core\Manifest\ManifestCache;
use SilverStripe\Core\Manifest\ManifestFileFinder;

/**
 * A class which builds a manifest of all themes (which is really just a directory called "templates")
 */
class ThemeManifest implements ThemeList {

	const TEMPLATES_DIR = 'templates';

	/**
	 * Base path
	 *
	 * @var string
	 */
	protected $base;

	/**
	 * Include tests
	 *
	 * @var bool
	 */
	protected $tests;

	/**
	 * Path to application code
	 *
	 * @var string
	 */
	protected $project;

	/**
	 * Cache
	 *
	 * @var ManifestCache
	 */
	protected $cache;

	/**
	 * Cache key
	 *
	 * @var string
	 */
	protected $cacheKey;

	/**
	 * List of theme root directories
	 *
	 * @var string
	 */
	protected $themes = null;

	/**
	 * Constructs a new template manifest. The manifest is not actually built
	 * or loaded from cache until needed.
	 *
	 * @param string $base The base path.
	 * @param string $project Path to application code
	 *
	 * @param bool $includeTests Include tests in the manifest.
	 * @param bool $forceRegen Force the manifest to be regenerated.
	 */
	public function __construct($base, $project, $includeTests = false, $forceRegen = false) {
		$this->base  = $base;
		$this->tests = $includeTests;

		$this->project = $project;

		$cacheClass = defined('SS_MANIFESTCACHE')
			? SS_MANIFESTCACHE
			: 'SilverStripe\\Core\\Manifest\\ManifestCache_File';

		$this->cache = new $cacheClass('thememanifest'.($includeTests ? '_tests' : ''));
		$this->cacheKey = $this->getCacheKey();

		if ($forceRegen) {
			$this->regenerate();
		}
	}

	/**
	 * @return string
	 */
	public function getBase() {
		return $this->base;
	}

	/**
	 * Generate a unique cache key to avoid manifest cache collisions.
	 * We compartmentalise based on the base path, the given project, and whether
	 * or not we intend to include tests.
	 * @return string
	 */
	public function getCacheKey() {
		return sha1(sprintf(
			"manifest-%s-%s-%u",
			$this->base,
			$this->project,
			$this->tests
		));
	}

	public function getThemes() {
		if ($this->themes === null) {
			$this->init();
		}
		return $this->themes;
	}

	/**
	 * Regenerates the manifest by scanning the base path.
	 *
	 * @param bool $cache
	 */
	public function regenerate($cache = true) {
		$finder = new ManifestFileFinder();
		$finder->setOptions(array(
			'include_themes' => false,
			'ignore_dirs' => array('node_modules', THEMES_DIR),
			'ignore_tests'  => !$this->tests,
			'dir_callback'  => array($this, 'handleDirectory')
		));

		$this->themes = [];
		$finder->find($this->base);

		if ($cache) {
			$this->cache->save($this->themes, $this->cacheKey);
		}
	}

	/**
	 * Add a directory to the manifest
	 *
	 * @param string $basename
	 * @param string $pathname
	 * @param int $depth
	 */
	public function handleDirectory($basename, $pathname, $depth)
	{
		if ($basename !== self::TEMPLATES_DIR) {
			return;
		}

		// We only want part of the full path, so split into directories
		$parts = explode('/', $pathname);
		// Take the end (the part relative to base), except the very last directory
		$themeParts = array_slice($parts, -$depth, $depth-1);
		// Then join again
		$path = '/'.implode('/', $themeParts);

		// If this is in the project, add to beginning of list. Else add to end.
		if ($themeParts[0] == $this->project) {
			array_unshift($this->themes, $path);
		}
		else {
			array_push($this->themes, $path);
		}
	}

	/**
	 * Initialise the manifest
	 */
	protected function init() {
		if ($data = $this->cache->load($this->cacheKey)) {
			$this->themes = $data;
		} else {
			$this->regenerate();
		}
	}
}