<?php
/**
 * Pagination helper — แสดง pager + per-page selector
 * ใช้ร่วมกับการกรองข้อมูลฝั่ง PHP (array_slice)
 */

if (!function_exists('paginationParams')) {
    /**
     * อ่าน page + per_page จาก $_GET พร้อม sanitize
     */
    function paginationParams(int $default_per_page = 20): array {
        $page = max(1, (int)($_GET['page'] ?? 1));
        $per_page = (int)($_GET['per_page'] ?? $default_per_page);
        if (!in_array($per_page, [20, 50, 100, 150], true)) $per_page = $default_per_page;
        return [$page, $per_page, ($page - 1) * $per_page];
    }
}

if (!function_exists('paginateSql')) {
    /**
     * สร้าง pagination info จาก total ที่ query มาแล้ว (ใช้คู่กับ DB-level LIMIT/OFFSET)
     */
    function paginateSql(int $total, int $page, int $per_page): array {
        if (!in_array($per_page, [20, 50, 100, 150], true)) $per_page = 20;
        $total_pages = max(1, (int)ceil($total / $per_page));
        if ($page < 1) $page = 1;
        if ($page > $total_pages) $page = $total_pages;
        return [
            'items'       => [],     // ฝั่ง caller เซ็ตเอง
            'total'       => $total,
            'total_pages' => $total_pages,
            'page'        => $page,
            'per_page'    => $per_page,
        ];
    }
}

if (!function_exists('paginateArray')) {
    /**
     * แบ่งหน้าจาก array
     * @return array [items_for_page, total, total_pages, current_page, per_page]
     */
    function paginateArray(array $items, int $page = 1, int $per_page = 20): array {
        $allowed = [20, 50, 100, 150];
        if (!in_array($per_page, $allowed, true)) $per_page = 20;

        $total = count($items);
        $total_pages = max(1, (int)ceil($total / $per_page));
        if ($page < 1) $page = 1;
        if ($page > $total_pages) $page = $total_pages;

        $offset = ($page - 1) * $per_page;
        $slice = array_slice(array_values($items), $offset, $per_page);

        return [
            'items'       => $slice,
            'total'       => $total,
            'total_pages' => $total_pages,
            'page'        => $page,
            'per_page'    => $per_page,
        ];
    }
}

if (!function_exists('renderPagination')) {
    /**
     * แสดง pagination control แบบ <1 2 3 ... 500>
     * @param array $info ผลจาก paginateArray()
     * @param array $base_params พารามิเตอร์ GET อื่นๆ ที่ต้องคงไว้ในลิงก์
     */
    function renderPagination(array $info, array $base_params = []): void {
        $page        = $info['page'];
        $total_pages = $info['total_pages'];
        $per_page    = $info['per_page'];
        $total       = $info['total'];

        // ล้าง page/per_page จาก base
        unset($base_params['page']);

        $build = function($p) use ($base_params) {
            $base_params['page'] = $p;
            return '?' . http_build_query($base_params);
        };
        $build_pp = function($pp) use ($base_params) {
            $base_params['per_page'] = $pp;
            $base_params['page'] = 1;
            return '?' . http_build_query($base_params);
        };

        // คำนวณช่วงเลขหน้าที่จะโชว์ (window ขนาด 5 รอบหน้าปัจจุบัน + first/last)
        $window = 2;
        $pages = [];
        $start = max(2, $page - $window);
        $end   = min($total_pages - 1, $page + $window);
        $pages[] = 1;
        if ($start > 2) $pages[] = '…';
        for ($i = $start; $i <= $end; $i++) $pages[] = $i;
        if ($end < $total_pages - 1) $pages[] = '…';
        if ($total_pages > 1) $pages[] = $total_pages;

        $from = $total === 0 ? 0 : (($page - 1) * $per_page + 1);
        $to   = min($page * $per_page, $total);
        static $css_printed = false;
        if (!$css_printed):
            $css_printed = true; ?>
        <style>
            .dlr-pager { display:flex; flex-wrap:wrap; justify-content:space-between; align-items:center; gap:14px; padding:14px 16px; background:#fafafa; border-top:1px solid #e5e7eb; border-radius:0 0 12px 12px; font-family:inherit; }
            .dlr-pager .info { color:#6b7280; font-size:0.85rem; }
            .dlr-pager .info strong { color:#374151; }
            .dlr-pager .pp-wrap { display:flex; align-items:center; gap:8px; color:#6b7280; font-size:0.85rem; }
            .dlr-pager .pp-wrap select { padding:5px 28px 5px 10px; border:1px solid #d1d5db; border-radius:8px; background:#fff; font-size:0.85rem; cursor:pointer; }
            .dlr-pager .pp-wrap select:focus { outline:none; border-color:#6a5acd; box-shadow:0 0 0 3px rgba(106,90,205,0.15); }
            .dlr-pager .pager { display:flex; align-items:center; gap:4px; list-style:none; padding:0; margin:0; flex-wrap:wrap; }
            .dlr-pager .pager a, .dlr-pager .pager span { display:inline-flex; align-items:center; justify-content:center; min-width:34px; height:34px; padding:0 10px; border:1px solid #e5e7eb; border-radius:8px; color:#374151; text-decoration:none; font-size:0.85rem; font-weight:600; background:#fff; transition:all .15s ease; }
            .dlr-pager .pager a:hover { background:#f3f4f6; border-color:#6a5acd; color:#6a5acd; }
            .dlr-pager .pager .active { background:#6a5acd; border-color:#6a5acd; color:#fff; cursor:default; }
            .dlr-pager .pager .disabled { color:#cbd5e1; background:#f9fafb; cursor:not-allowed; pointer-events:none; }
            .dlr-pager .pager .ellipsis { border:none; background:transparent; color:#9ca3af; min-width:auto; }
            @media (max-width: 600px) {
                .dlr-pager { flex-direction:column; align-items:stretch; text-align:center; }
                .dlr-pager .pager { justify-content:center; }
            }
        </style>
        <?php endif; ?>
        <div class="dlr-pager">
            <div class="info">
                แสดง <strong><?php echo $from; ?>–<?php echo $to; ?></strong> จาก <strong><?php echo number_format($total); ?></strong> รายการ
            </div>

            <div class="pp-wrap">
                <span>ต่อหน้า:</span>
                <select onchange="window.location.href=this.value;">
                    <?php foreach ([20, 50, 100, 150] as $pp): ?>
                        <option value="<?php echo htmlspecialchars($build_pp($pp)); ?>" <?php echo $pp === $per_page ? 'selected' : ''; ?>>
                            <?php echo $pp; ?>
                        </option>
                    <?php endforeach; ?>
                </select>
            </div>

            <nav>
                <ul class="pager">
                    <li>
                        <?php if ($page <= 1): ?>
                            <span class="disabled">&laquo;</span>
                        <?php else: ?>
                            <a href="<?php echo htmlspecialchars($build($page - 1)); ?>" title="ก่อนหน้า">&laquo;</a>
                        <?php endif; ?>
                    </li>
                    <?php foreach ($pages as $p): ?>
                        <li>
                            <?php if ($p === '…'): ?>
                                <span class="ellipsis">…</span>
                            <?php elseif ($p === $page): ?>
                                <span class="active"><?php echo $p; ?></span>
                            <?php else: ?>
                                <a href="<?php echo htmlspecialchars($build($p)); ?>"><?php echo $p; ?></a>
                            <?php endif; ?>
                        </li>
                    <?php endforeach; ?>
                    <li>
                        <?php if ($page >= $total_pages): ?>
                            <span class="disabled">&raquo;</span>
                        <?php else: ?>
                            <a href="<?php echo htmlspecialchars($build($page + 1)); ?>" title="ถัดไป">&raquo;</a>
                        <?php endif; ?>
                    </li>
                </ul>
            </nav>
        </div>
        <?php
    }
}