<?php

declare(strict_types=1);

namespace Infrastructure\Persistence;

// @responsibility: Persistenz für Chat-Sessions (CRUD, UUID-Lookup)

use Domain\Entity\ChatSession;
use Domain\Factory\ChatSessionFactory;
use Domain\Repository\ChatSessionRepositoryInterface;

class ChatSessionRepository implements ChatSessionRepositoryInterface
{
    private \PDO $pdo;

    public function __construct(\PDO $pdo)
    {
        $this->pdo = $pdo;
    }

    public function findByUuid(string $uuid): ?ChatSession
    {
        $stmt = $this->pdo->prepare('SELECT * FROM chat_sessions WHERE uuid = ?');
        $stmt->execute([$uuid]);
        $result = $stmt->fetch(\PDO::FETCH_ASSOC);

        return $result !== false ? ChatSessionFactory::fromArray($result) : null;
    }

    public function findAll(int $limit = 50): array
    {
        $stmt = $this->pdo->query(
            'SELECT * FROM chat_sessions ORDER BY last_activity DESC LIMIT ' . $limit
        );

        $sessions = [];
        foreach ($stmt->fetchAll(\PDO::FETCH_ASSOC) as $row) {
            $sessions[] = ChatSessionFactory::fromArray($row);
        }

        return $sessions;
    }

    public function findAllWithStats(int $limit = 50): array
    {
        $stmt = $this->pdo->query(
            'SELECT s.*,
                    (SELECT COUNT(*) FROM chat_messages WHERE session_id = s.id) as message_count,
                    (SELECT COALESCE(SUM(tokens_input), 0) FROM chat_messages WHERE session_id = s.id) as total_input_tokens,
                    (SELECT COALESCE(SUM(tokens_output), 0) FROM chat_messages WHERE session_id = s.id) as total_output_tokens,
                    (SELECT COALESCE(SUM(end_microtime - start_microtime), 0) FROM chat_messages WHERE session_id = s.id AND start_microtime IS NOT NULL) as total_duration,
                    (SELECT model FROM chat_messages WHERE session_id = s.id AND role = "assistant" ORDER BY id DESC LIMIT 1) as last_model
             FROM chat_sessions s
             ORDER BY s.last_activity DESC
             LIMIT ' . $limit
        );

        return $stmt->fetchAll(\PDO::FETCH_ASSOC);
    }

    public function save(ChatSession $session): int
    {
        if ($session->getId() !== null) {
            // Update
            $stmt = $this->pdo->prepare(
                'UPDATE chat_sessions SET
                    title = ?, model = ?, collections = ?, context_limit = ?,
                    temperature = ?, max_tokens = ?, author_profile_id = ?,
                    system_prompt_id = ?, updated_at = NOW()
                 WHERE id = ?'
            );
            $stmt->execute([
                $session->getTitle(),
                $session->getModel(),
                json_encode($session->getCollections()),
                $session->getContextLimit(),
                $session->getTemperature(),
                $session->getMaxTokens(),
                $session->getAuthorProfileId(),
                $session->getSystemPromptId(),
                $session->getId(),
            ]);

            return $session->getId();
        }

        // Insert
        $stmt = $this->pdo->prepare(
            'INSERT INTO chat_sessions (uuid, model, collections, context_limit, temperature, max_tokens)
             VALUES (?, ?, ?, ?, ?, ?)'
        );
        $stmt->execute([
            $session->getUuid(),
            $session->getModel(),
            json_encode($session->getCollections()),
            $session->getContextLimit(),
            $session->getTemperature(),
            $session->getMaxTokens(),
        ]);

        return (int) $this->pdo->lastInsertId();
    }

    public function create(string $uuid, string $model, string $collections, int $contextLimit): int
    {
        $stmt = $this->pdo->prepare(
            'INSERT INTO chat_sessions (uuid, model, collections, context_limit) VALUES (?, ?, ?, ?)'
        );
        $stmt->execute([$uuid, $model, $collections, $contextLimit]);

        return (int) $this->pdo->lastInsertId();
    }

    public function updateTitle(int $sessionId, string $title): void
    {
        $stmt = $this->pdo->prepare('UPDATE chat_sessions SET title = ? WHERE id = ?');
        $stmt->execute([$title, $sessionId]);
    }

    public function updateSettings(
        int $sessionId,
        string $model,
        array $collections,
        int $contextLimit,
        ?int $authorProfileId,
        float $temperature,
        int $maxTokens
    ): void {
        $collectionsJson = json_encode($collections);
        $stmt = $this->pdo->prepare(
            'UPDATE chat_sessions SET model = ?, collections = ?, context_limit = ?, author_profile_id = ?, temperature = ?, max_tokens = ? WHERE id = ?'
        );
        $stmt->execute([
            $model,
            $collectionsJson,
            $contextLimit,
            $authorProfileId > 0 ? $authorProfileId : null,
            $temperature,
            $maxTokens,
            $sessionId,
        ]);
    }

    public function updateSystemPrompt(int $sessionId, ?string $systemPrompt): void
    {
        $stmt = $this->pdo->prepare('UPDATE chat_sessions SET system_prompt = ? WHERE id = ?');
        $stmt->execute([$systemPrompt !== '' ? $systemPrompt : null, $sessionId]);
    }

    public function delete(int $sessionId): void
    {
        $stmt = $this->pdo->prepare('DELETE FROM chat_sessions WHERE id = ?');
        $stmt->execute([$sessionId]);
    }

    public function touch(int $sessionId): void
    {
        $stmt = $this->pdo->prepare('UPDATE chat_sessions SET updated_at = NOW() WHERE id = ?');
        $stmt->execute([$sessionId]);
    }

    public function generateUuid(): string
    {
        $data = random_bytes(16);
        $data[6] = chr(ord($data[6]) & 0x0f | 0x40);
        $data[8] = chr(ord($data[8]) & 0x3f | 0x80);

        return vsprintf('%s%s-%s-%s-%s-%s%s%s', str_split(bin2hex($data), 4));
    }
}