<?php

declare(strict_types=1);

namespace Phred\Support;

final class Config
{
    /** @var array<string,mixed>|null */
    private static ?array $store = null;

    /**
     * Get configuration value with precedence:
     * 1) Environment variables (UPPER_CASE or dot.notation translated)
     * 2) Loaded config files from config/*.php, accessible via dot.notation (e.g., app.env)
     * 3) Provided $default
     */
    public static function get(string $key, mixed $default = null): mixed
    {
        // 1) Environment lookup (supports dot.notation by converting to UPPER_SNAKE)
        $envKey = strtoupper(str_replace('.', '_', $key));
        $value = getenv($envKey);
        if ($value !== false) {
            return $value;
        }
        if (isset($_SERVER[$envKey])) {
            return $_SERVER[$envKey];
        }
        if (isset($_ENV[$envKey])) {
            return $_ENV[$envKey];
        }

        // 2) Config files (lazy load once)
        self::ensureLoaded();
        if (self::$store) {
            $fromStore = self::getFromStore($key);
            if ($fromStore !== null) {
                return $fromStore;
            }
        }

        // 3) Default
        return $default;
    }

    private static function ensureLoaded(): void
    {
        if (self::$store !== null) {
            return;
        }
        self::$store = [];
        $root = getcwd();
        $configDir = $root . DIRECTORY_SEPARATOR . 'config';
        if (!is_dir($configDir)) {
            return; // no config directory; keep empty store
        }
        foreach (glob($configDir . '/*.php') ?: [] as $file) {
            $key = basename($file, '.php');
            try {
                $data = require $file;
                if (is_array($data)) {
                    self::$store[$key] = $data;
                }
            } catch (\Throwable) {
                // ignore malformed config files to avoid breaking runtime
            }
        }
    }

    private static function getFromStore(string $key): mixed
    {
        // dot.notation: first segment is file key, remaining traverse array
        if (str_contains($key, '.')) {
            $parts = explode('.', $key);
            $rootKey = array_shift($parts);
            if ($rootKey === null || !isset(self::$store[$rootKey])) {
                return null;
            }
            $cursor = self::$store[$rootKey];
            foreach ($parts as $p) {
                if (is_array($cursor) && array_key_exists($p, $cursor)) {
                    $cursor = $cursor[$p];
                } else {
                    return null;
                }
            }
            return $cursor;
        }

        // non-dotted: try exact file key
        return self::$store[$key] ?? null;
    }
}