<?php

declare(strict_types=1);

namespace App\Storage;

use App\App\Bootstrap;
use RuntimeException;

final class JsonStore
{
    /** @var array<string, mixed> */
    private array $app;

    public function __construct()
    {
        $this->app = Bootstrap::config('app');
    }

    public function emailKey(string $email): string
    {
        return hash('sha256', strtolower(trim($email)));
    }

    /** @return array<string, mixed>|null */
    public function getDraft(string $email): ?array
    {
        $path = $this->draftPath($email);
        if (!is_file($path)) {
            return null;
        }

        return $this->readJsonFile($path);
    }

    /** @return array<string, mixed>|null */
    public function getSubmissionByEmail(string $email): ?array
    {
        $path = $this->submissionPath($email);
        if (!is_file($path)) {
            return null;
        }

        return $this->readJsonFile($path);
    }

    public function hasSubmission(string $email): bool
    {
        return is_file($this->submissionPath($email));
    }

    /**
     * @param array<string, mixed> $draft
     * @return array<string, mixed>
     */
    public function saveDraft(string $email, array $draft): array
    {
        $now = date('c');
        $expires = date('c', time() + ((int) ($this->app['retention']['draft_days'] ?? 14) * 86400));

        $current = $this->getDraft($email) ?? [];

        $payload = [
            'email' => strtolower(trim($email)),
            'application_key' => $this->emailKey($email),
            'status' => 'draft',
            'created_at' => $current['created_at'] ?? $now,
            'updated_at' => $now,
            'expires_at' => $expires,
            'step' => $draft['step'] ?? ($current['step'] ?? 1),
            'form_data' => array_merge((array) ($current['form_data'] ?? []), (array) ($draft['form_data'] ?? [])),
            'uploads' => $this->mergeUploads((array) ($current['uploads'] ?? []), (array) ($draft['uploads'] ?? [])),
        ];

        $this->writeJsonFile($this->draftPath($email), $payload);

        return $payload;
    }

    /**
     * Replaces the full draft payload for an email (no upload merge).
     *
     * @param array<string, mixed> $draft
     * @return array<string, mixed>
     */
    public function replaceDraft(string $email, array $draft): array
    {
        $now = date('c');
        $expires = date('c', time() + ((int) ($this->app['retention']['draft_days'] ?? 14) * 86400));

        $current = $this->getDraft($email) ?? [];

        $payload = [
            'email' => strtolower(trim($email)),
            'application_key' => $this->emailKey($email),
            'status' => 'draft',
            'created_at' => $current['created_at'] ?? $now,
            'updated_at' => $now,
            'expires_at' => $expires,
            'step' => $draft['step'] ?? ($current['step'] ?? 1),
            'form_data' => (array) ($draft['form_data'] ?? []),
            'uploads' => (array) ($draft['uploads'] ?? []),
        ];

        $this->writeJsonFile($this->draftPath($email), $payload);

        return $payload;
    }

    /**
     * @param array<string, mixed> $submission
     * @return array<string, mixed>
     */
    public function saveSubmission(string $email, array $submission): array
    {
        $now = date('c');
        $expires = date('c', time() + ((int) ($this->app['retention']['submission_days'] ?? 90) * 86400));
        $draft = $this->getDraft($email) ?? [];

        $payload = [
            'email' => strtolower(trim($email)),
            'application_key' => $this->emailKey($email),
            'status' => 'submitted',
            'created_at' => $draft['created_at'] ?? $now,
            'updated_at' => $now,
            'submitted_at' => $now,
            'expires_at' => $expires,
            'step' => $submission['step'] ?? ($draft['step'] ?? null),
            'form_data' => (array) ($submission['form_data'] ?? []),
            'uploads' => (array) ($submission['uploads'] ?? []),
        ];

        $this->writeJsonFile($this->submissionPath($email), $payload);
        $this->deleteDraft($email);

        return $payload;
    }

    public function deleteDraft(string $email): void
    {
        $path = $this->draftPath($email);
        if (is_file($path)) {
            unlink($path);
        }
    }

    /** @return array<string, mixed>|null */
    public function getSubmissionByKey(string $applicationKey): ?array
    {
        $safeKey = $this->normalizeApplicationKey($applicationKey);
        if ($safeKey === null) {
            return null;
        }

        $path = rtrim((string) $this->app['storage']['submissions'], '/') . '/' . $safeKey . '.json';
        if (!is_file($path)) {
            return null;
        }

        return $this->readJsonFile($path);
    }

    /** @return array<int, array<string, mixed>> */
    public function listSubmissions(): array
    {
        $dir = (string) $this->app['storage']['submissions'];
        $files = glob($dir . '/*.json') ?: [];
        $list = [];

        foreach ($files as $file) {
            $item = $this->readJsonFile($file);
            if (!is_array($item)) {
                continue;
            }
            $list[] = $item;
        }

        usort(
            $list,
            static fn (array $a, array $b): int => strcmp((string) ($b['submitted_at'] ?? ''), (string) ($a['submitted_at'] ?? ''))
        );

        return $list;
    }

    public function deleteSubmissionByKey(string $applicationKey): void
    {
        $safeKey = $this->normalizeApplicationKey($applicationKey);
        if ($safeKey === null) {
            return;
        }

        $submissionPath = rtrim((string) $this->app['storage']['submissions'], '/') . '/' . $safeKey . '.json';
        if (is_file($submissionPath)) {
            $submission = $this->readJsonFile($submissionPath);
            if (isset($submission['email']) && is_string($submission['email'])) {
                $this->deleteDraft($submission['email']);
            }
            unlink($submissionPath);
        }
    }

    /**
     * @template T
     * @param callable():T $callback
     * @return T
     */
    public function withEmailLock(string $email, callable $callback): mixed
    {
        $locksDir = (string) $this->app['storage']['locks'];
        if (!is_dir($locksDir)) {
            mkdir($locksDir, 0775, true);
        }

        $lockFile = $locksDir . '/' . $this->emailKey($email) . '.lock';
        $handle = fopen($lockFile, 'c+');

        if ($handle === false) {
            throw new RuntimeException('Could not open lock file.');
        }

        try {
            if (!flock($handle, LOCK_EX)) {
                throw new RuntimeException('Could not acquire lock.');
            }

            return $callback();
        } finally {
            flock($handle, LOCK_UN);
            fclose($handle);
        }
    }

    private function draftPath(string $email): string
    {
        return rtrim((string) $this->app['storage']['drafts'], '/') . '/' . $this->emailKey($email) . '.json';
    }

    private function submissionPath(string $email): string
    {
        return rtrim((string) $this->app['storage']['submissions'], '/') . '/' . $this->emailKey($email) . '.json';
    }

    /** @return array<string, mixed> */
    private function readJsonFile(string $path): array
    {
        $raw = file_get_contents($path);
        if ($raw === false || $raw === '') {
            return [];
        }

        $decoded = json_decode($raw, true);
        if (!is_array($decoded)) {
            return [];
        }

        return $decoded;
    }

    /** @param array<string, mixed> $data */
    private function writeJsonFile(string $path, array $data): void
    {
        $tmpPath = $path . '.tmp';
        file_put_contents($tmpPath, json_encode($data, JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES));
        rename($tmpPath, $path);
    }

    /**
     * @param array<string, mixed> $existing
     * @param array<string, mixed> $incoming
     * @return array<string, mixed>
     */
    private function mergeUploads(array $existing, array $incoming): array
    {
        foreach ($incoming as $field => $files) {
            if (!is_array($files)) {
                continue;
            }
            $existing[$field] = array_values(array_merge((array) ($existing[$field] ?? []), $files));
        }

        return $existing;
    }

    private function normalizeApplicationKey(string $key): ?string
    {
        $key = strtolower(trim($key));
        if (!preg_match('/^[a-f0-9]{64}$/', $key)) {
            return null;
        }

        return $key;
    }
}