<?php

declare(strict_types=1);

namespace App;

final class RegistrationStore
{
    public function __construct(
        private readonly string $storagePath,
    ) {
    }

    /**
     * @return array<int, array<string, mixed>>
     */
    public function all(): array
    {
        $items = $this->read();
        usort(
            $items,
            static fn (array $left, array $right): int => strcmp(
                (string) ($right['created_at'] ?? ''),
                (string) ($left['created_at'] ?? '')
            )
        );

        return $items;
    }

    /**
     * @return array<string, mixed>|null
     */
    public function find(string $id): ?array
    {
        foreach ($this->read() as $item) {
            if ((string) ($item['id'] ?? '') === $id) {
                return $item;
            }
        }

        return null;
    }

    /**
     * @return array<string, mixed>|null
     */
    public function findConflict(string $username, string $email): ?array
    {
        $username = strtolower(trim($username));
        $email = strtolower(trim($email));

        foreach ($this->read() as $item) {
            $status = (string) ($item['status'] ?? 'pending');

            if ($status === 'rejected') {
                continue;
            }

            if (strtolower((string) ($item['username'] ?? '')) === $username) {
                return $item;
            }

            if (strtolower((string) ($item['email'] ?? '')) === $email) {
                return $item;
            }
        }

        return null;
    }

    /**
     * @param array<string, mixed> $payload
     * @return array<string, mixed>
     */
    public function create(array $payload): array
    {
        $items = $this->read();
        $items[] = $payload;
        $this->write($items);

        return $payload;
    }

    /**
     * @param callable(array<string, mixed>): array<string, mixed> $mutator
     * @return array<string, mixed>|null
     */
    public function update(string $id, callable $mutator): ?array
    {
        $items = $this->read();
        $updated = null;

        foreach ($items as $index => $item) {
            if ((string) ($item['id'] ?? '') !== $id) {
                continue;
            }

            $items[$index] = $mutator($item);
            $updated = $items[$index];
            break;
        }

        if ($updated === null) {
            return null;
        }

        $this->write($items);

        return $updated;
    }

    /**
     * @return array<int, array<string, mixed>>
     */
    private function read(): array
    {
        if (!is_file($this->storagePath)) {
            return [];
        }

        $raw = file_get_contents($this->storagePath);

        if ($raw === false || trim($raw) === '') {
            return [];
        }

        $decoded = json_decode($raw, true);

        return is_array($decoded) ? array_values(array_filter($decoded, 'is_array')) : [];
    }

    /**
     * @param array<int, array<string, mixed>> $items
     */
    private function write(array $items): void
    {
        $directory = dirname($this->storagePath);

        if (!is_dir($directory)) {
            mkdir($directory, 0775, true);
        }

        file_put_contents(
            $this->storagePath,
            json_encode($items, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE) . PHP_EOL,
            LOCK_EX
        );
    }
}