<?php

namespace App\Config;

/**
 * A class to load a config into an array
 * Throws an exception if it fails to laod
 *
 * @author Phil Burton <phil@pgburton.com>
 */
class Loader
{
    /**
     * A loaded config array
     *
     * @var mixed[]
     */
    protected $config;

    /**
     * Try and load a config
     *
     * @author Phil Burton <phil@pgburton.com>
     */
    public function __construct()
    {
        foreach ($this->getConfigPaths() as $path) {
            if ($config = $this->loadConfig($path)) {
                $this->validate();
                $this->clean();
                return;
            }
        }

        // No config found
        throw new \Exception('Could not find config file.');
    }

    /**
     * Try and load a config file
     * If we can't return false
     *
     * @author Phil Burton <phil@pgburton.com>
     * @return mixed[]|false
     */
    public function loadConfig(string $path)
    {
        $filename = $path . '/' . $this->getConfigFilename();

        if (!$this->config) {
            if (!file_exists($filename)) {
                return false;
            }

            if (!is_readable($filename)) {
                return false;
            }

            if (!$config = include($filename)) {
                return false;
            }

            $this->config = $config;
        }

        return $this->config;
    }

    /**
     * Return the nsam of the config file to load
     *
     * @author Phil Burton <phil@pgburton.com>
     * @return string;
     */
    public function getConfigFilename()
    {
        return 'dipper.php';
    }

    /**
     * Make sure the config is up to scratch
     *
     * @author Phil Burton <phil@pgburton.com>
     */
    public function validate()
    {
        $config = $this->getConfig();

        foreach ($this->getRequired() as $required) {
            if (!isset($config[$required])) {
                throw new \Exception("Could not find " . $required . " in config file.");
            }
        }
    }

    /**
     * Clean up the config ready for use
     *
     * @author Phil Burton <phil@pgburton.com>
     */
    public function clean()
    {
        $config = $this->getConfig();
        foreach ($config as &$item) {
            // Remove trailing slashes
            $item = rtrim($item, "/");
        }

        $this->config = $config;
    }

    /**
     * Return the array of config paths
     *
     * @author Phil Burton <phil@pgburton.com>
     * @return string[]
     */
    public function getConfigPaths()
    {
        return [
            realpath(dirname(__FILE__) . "/../../"), // Root of dipper
            realpath(dirname(__FILE__) . "/../../config") // Config directory in dipper
        ];
    }

    /**
     * Return the loaded config
     *
     * @author Phil Burton <phil@pgburton.com>
     * @return mixed[]
     */
    public function getConfig()
    {
        return $this->config;
    }

    /**
     * Return the required config keys
     *
     * @author Phil Burton <phil@pgburton.com>
     * @return string[]
     */
    public function getRequired()
    {
        return [
            "SITES_ROOT",
            "CONFIG_ROOT"
        ];
    }
}