<?php

declare(strict_types=1);

/** @param array<string, mixed> $customer */
function parseCustomerCustomFields(array &$customer): void
{
    /** @var array<mixed>|null $cfRaw */
    $cfRaw = !empty($customer['custom_fields'])
        ? json_decode($customer['custom_fields'], true)
        : null;
    if (is_array($cfRaw) && !isset($cfRaw['fields'])) {
        $customer['custom_fields'] = $cfRaw;
        $customer['customer_field_order'] = null;
    } elseif (is_array($cfRaw) && isset($cfRaw['fields'])) {
        $customer['custom_fields'] = $cfRaw['fields'];
        $customer['customer_field_order'] = $cfRaw['field_order'] ?? $cfRaw['fieldOrder'] ?? null;
    } else {
        $customer['custom_fields'] = [];
        $customer['customer_field_order'] = null;
    }
}

/** @param array<string, mixed> $input */
function encodeCustomerCustomFields(array $input, ?string $existingJson): ?string
{
    if (!array_key_exists('custom_fields', $input) && !array_key_exists('customer_field_order', $input)) {
        return $existingJson;
    }
    /** @var array<mixed>|null $currentRaw */
    $currentRaw = !empty($existingJson) ? json_decode($existingJson, true) : null;
    if (is_array($currentRaw) && !isset($currentRaw['fields'])) {
        /** @var array<string, mixed> $stored */
        $stored = ['fields' => $currentRaw, 'field_order' => null];
    } elseif (is_array($currentRaw) && isset($currentRaw['fields'])) {
        /** @var array<string, mixed> $stored */
        $stored = $currentRaw;
    } else {
        $stored = ['fields' => [], 'field_order' => null];
    }

    if (array_key_exists('custom_fields', $input) && is_array($input['custom_fields'])) {
        $stored['fields'] = $input['custom_fields'];
    }
    if (array_key_exists('customer_field_order', $input)) {
        $stored['field_order'] = is_array($input['customer_field_order']) ? $input['customer_field_order'] : null;
    }

    unset($stored['fieldOrder']);

    return json_encode($stored, JSON_UNESCAPED_UNICODE);
}

function handleGetAll(PDO $pdo): void
{
    $stmt = $pdo->query('
        SELECT c.id, c.name, c.street, c.city, c.postal_code, c.country,
               c.company_id, c.vat_id, c.custom_fields, c.created_at,
               COUNT(q.id) as quotation_count
        FROM customers c
        LEFT JOIN quotations q ON q.customer_id = c.id
        GROUP BY c.id
        ORDER BY c.name ASC
    ');
    $customers = $stmt->fetchAll();

    foreach ($customers as &$c) {
        parseCustomerCustomFields($c);
    }
    unset($c);

    successResponse(['customers' => $customers]);
}

function handleGetOne(PDO $pdo, int $id): void
{
    $stmt = $pdo->prepare(
        'SELECT id, name, street, city, postal_code, country,
                company_id, vat_id, custom_fields, created_at
        FROM customers WHERE id = ?'
    );
    $stmt->execute([$id]);
    $customer = $stmt->fetch();

    if (!$customer) {
        errorResponse('Zákazník nebyl nalezen', 404);
    }

    parseCustomerCustomFields($customer);
    successResponse($customer);
}

function handleSearch(PDO $pdo): void
{
    $q = trim($_GET['q'] ?? '');
    if (strlen($q) < 1 || mb_strlen($q) > 100) {
        successResponse(['customers' => []]);
        return;
    }

    $stmt = $pdo->prepare('
        SELECT id, name, street, city, postal_code, country,
               company_id, vat_id, custom_fields
        FROM customers
        WHERE name LIKE ? OR company_id LIKE ? OR city LIKE ?
        ORDER BY name ASC
        LIMIT 20
    ');
    $search = "%{$q}%";
    $stmt->execute([$search, $search, $search]);

    $results = $stmt->fetchAll();
    foreach ($results as &$c) {
        parseCustomerCustomFields($c);
    }
    unset($c);
    successResponse(['customers' => $results]);
}

function handleCreateCustomer(PDO $pdo): void
{
    $input = getJsonInput();

    if (empty($input['name'])) {
        errorResponse('Název zákazníka je povinný');
    }
    if (mb_strlen($input['name']) > 255) {
        errorResponse('Název zákazníka je příliš dlouhý (max 255 znaků)');
    }
    foreach (['street', 'city', 'country'] as $f) {
        if (isset($input[$f]) && mb_strlen($input[$f]) > 255) {
            errorResponse("Pole $f je příliš dlouhé (max 255 znaků)");
        }
    }
    if (isset($input['postal_code']) && mb_strlen($input['postal_code']) > 20) {
        errorResponse('PSČ je příliš dlouhé (max 20 znaků)');
    }
    if (isset($input['company_id']) && mb_strlen($input['company_id']) > 50) {
        errorResponse('IČO je příliš dlouhé (max 50 znaků)');
    }
    if (isset($input['vat_id']) && mb_strlen($input['vat_id']) > 50) {
        errorResponse('DIČ je příliš dlouhé (max 50 znaků)');
    }

    $uuid = sprintf(
        '%04x%04x-%04x-%04x-%04x-%04x%04x%04x',
        random_int(0, 0xffff),
        random_int(0, 0xffff),
        random_int(0, 0xffff),
        random_int(0, 0x0fff) | 0x4000,
        random_int(0, 0x3fff) | 0x8000,
        random_int(0, 0xffff),
        random_int(0, 0xffff),
        random_int(0, 0xffff)
    );

    $customFieldsJson = encodeCustomerCustomFields($input, null);

    $stmt = $pdo->prepare('
        INSERT INTO customers (name, street, city, postal_code, country,
            company_id, vat_id, custom_fields, created_at, uuid, modified_at, sync_version)
        VALUES (?, ?, ?, ?, ?, ?, ?, ?, NOW(), ?, NOW(), 1)
    ');
    $stmt->execute([
        $input['name'],
        $input['street'] ?? '',
        $input['city'] ?? '',
        $input['postal_code'] ?? '',
        $input['country'] ?? '',
        $input['company_id'] ?? '',
        $input['vat_id'] ?? '',
        $customFieldsJson,
        $uuid,
    ]);

    $newId = (int)$pdo->lastInsertId();


    AuditLog::logCreate('customer', (int)$newId, [
        'name' => $input['name'],
    ], "Vytvořen zákazník '{$input['name']}'");

    successResponse(['id' => $newId], 'Zákazník byl vytvořen');
}

function handleUpdateCustomer(PDO $pdo, int $id): void
{
    $stmt = $pdo->prepare(
        'SELECT id, name, street, city, postal_code, country,
                company_id, vat_id, custom_fields
        FROM customers WHERE id = ?'
    );
    $stmt->execute([$id]);
    $existing = $stmt->fetch();

    if (!$existing) {
        errorResponse('Zákazník nebyl nalezen', 404);
    }

    $input = getJsonInput();

    // Delkove limity
    if (isset($input['name']) && mb_strlen($input['name']) > 255) {
        errorResponse('Název je příliš dlouhý (max 255 znaků)');
    }
    foreach (['street', 'city', 'country'] as $f) {
        if (isset($input[$f]) && mb_strlen($input[$f]) > 255) {
            errorResponse("Pole $f je příliš dlouhé (max 255 znaků)");
        }
    }
    if (isset($input['postal_code']) && mb_strlen($input['postal_code']) > 20) {
        errorResponse('PSČ je příliš dlouhé (max 20 znaků)');
    }
    if (isset($input['company_id']) && mb_strlen($input['company_id']) > 50) {
        errorResponse('IČO je příliš dlouhé (max 50 znaků)');
    }
    if (isset($input['vat_id']) && mb_strlen($input['vat_id']) > 50) {
        errorResponse('DIČ je příliš dlouhé (max 50 znaků)');
    }

    $customFieldsJson = encodeCustomerCustomFields($input, $existing['custom_fields'] ?? null);

    $stmt = $pdo->prepare('
        UPDATE customers SET
            name = ?,
            street = ?,
            city = ?,
            postal_code = ?,
            country = ?,
            company_id = ?,
            vat_id = ?,
            custom_fields = ?,
            modified_at = NOW(),
            sync_version = sync_version + 1
        WHERE id = ?
    ');
    $stmt->execute([
        $input['name'] ?? $existing['name'],
        $input['street'] ?? $existing['street'],
        $input['city'] ?? $existing['city'],
        $input['postal_code'] ?? $existing['postal_code'],
        $input['country'] ?? $existing['country'],
        $input['company_id'] ?? $existing['company_id'],
        $input['vat_id'] ?? $existing['vat_id'],
        $customFieldsJson,
        $id,
    ]);


    AuditLog::logUpdate(
        'customer',
        $id,
        ['name' => $existing['name']],
        ['name' => $input['name'] ?? $existing['name']],
        "Upraven zákazník #$id"
    );

    successResponse(null, 'Zákazník byl aktualizován');
}

function handleDeleteCustomer(PDO $pdo, int $id): void
{
    $stmt = $pdo->prepare('SELECT id, name FROM customers WHERE id = ?');
    $stmt->execute([$id]);
    $customer = $stmt->fetch();

    if (!$customer) {
        errorResponse('Zákazník nebyl nalezen', 404);
    }

    // Check if customer has quotations
    $stmt = $pdo->prepare('SELECT COUNT(*) FROM quotations WHERE customer_id = ?');
    $stmt->execute([$id]);
    $count = (int)$stmt->fetchColumn();

    if ($count > 0) {
        errorResponse("Zákazníka nelze smazat, má $count nabídek");
    }

    $stmt = $pdo->prepare('DELETE FROM customers WHERE id = ?');
    $stmt->execute([$id]);


    AuditLog::logDelete('customer', $id, ['name' => $customer['name']], "Smazán zákazník '{$customer['name']}'");

    successResponse(null, 'Zákazník byl smazán');
}