<?php
namespace Sasae\Loader;

use InvalidArgumentException;
use Twig\Source;
use Twig\Error\LoaderError;
use Twig\Loader\LoaderInterface;

/**
 * Provides a simpler Filesystem loader with mechanisms like namespaces omitted.
 */
class SasaeFilesystemLoader implements LoaderInterface {
    private string $root;

    /**
     * @param string $path Base path to the templates directory.
     */
    public function __construct(string $path) {
        $path = realpath($path);
        if($path === false)
            throw new InvalidArgumentException('$path does not exist.');
        $this->root = $path;
    }

    /**
     * Returns the underlying path.
     *
     * @return string
     */
    public function getPath(): string {
        return $this->root;
    }

    /** @var array<string, string> */
    private array $absPaths = [];

    private function getAbsolutePath(string $path, bool $throw): string {
        $cachePath = $path;
        if(array_key_exists($cachePath, $this->absPaths))
            return $this->absPaths[$cachePath];

        if(pathinfo($path, PATHINFO_EXTENSION) === '')
            $path = rtrim($path, '.') . '.twig';

        $absPath = realpath($this->root . DIRECTORY_SEPARATOR . $path);

        if($absPath === false) {
            if(!$throw)
                return '';

            throw new LoaderError(sprintf('Could not find template "%s" in "%s".', $path, $this->root));
        }

        if(!str_starts_with($absPath, $this->root)) {
            if(!$throw)
                return '';

            throw new LoaderError(sprintf('Attempting to load "%s" which is outside of the template directory.', $absPath));
        }

        return $this->absPaths[$cachePath] = $absPath;
    }

    public function getSourceContext(string $name): Source {
        $path = $this->getAbsolutePath($name, true);
        $body = file_get_contents($path);
        if($body === false)
            throw new LoaderError(sprintf('Was unable to read "%s"', $path));
        return new Source($body, $name, $path);
    }

    public function getCacheKey(string $name): string {
        return $this->getAbsolutePath($name, true);
    }

    public function isFresh(string $name, int $time): bool {
        return filemtime($this->getAbsolutePath($name, true)) < $time;
    }

    public function exists(string $name) {
        return $this->getAbsolutePath($name, false) !== '';
    }
}