// SvxPortal — web front-end for SvxReflector
// Copyright (C) 2026 SA7AUX (Björn)
// SPDX-License-Identifier: AGPL-3.0-or-later
//
// This program is free software: you can redistribute it and/or modify it under
// the terms of the GNU Affero General Public License as published by the Free
// Software Foundation, either version 3 of the License, or (at your option) any
// later version. See the LICENSE file for details.

// pager.js — shared pagination (dmr-web, svx-web).
// Canonical copy: <dmr-portal>/lib/pager.js; other repos carry a COPY.
//
//   pageSizeFor('monitorBody', 32, 160)   rows that fit below the element (min 5)
//   pagerHtml({page, pages, total, noun, cls})   footer « ‹ 1..n › » as HTML;
//       buttons carry class `cls` + data-pg, the page wires the click.
//   paginate.slice / totalPages / render(container, total, pageSize, page, onChange)
//       the container-driven pager (dmr-web lists), 1-based pages.
(function () {
  'use strict';
  function pageSizeFor(bodyId, rowPx, reservePx) {
    const body = document.getElementById(bodyId);
    const top = body ? body.getBoundingClientRect().top : 220;
    const avail = window.innerHeight - top - (reservePx == null ? 160 : reservePx);
    return Math.max(5, Math.floor(avail / (rowPx || 32)));
  }
  function pagerHtml(o) {
    const page = o.page, pages = o.pages, total = o.total, cls = o.cls || 'pg', noun = o.noun || 'rows';
    if (pages <= 1) return '';
    const span = 3;
    let from = Math.max(1, page - span), to = Math.min(pages, page + span);
    while (to - from < 6 && (from > 1 || to < pages)) { if (from > 1) from--; else if (to < pages) to++; }
    const btn = (label, target, dis, cur) =>
      `<button class="btn btn-sm ${cls} ${cur ? 'btn-primary' : 'btn-outline-secondary'} mx-1"${dis ? ' disabled' : ''}${target != null ? ` data-pg="${target}"` : ''} style="padding:1px 8px;">${label}</button>`;
    let h = `<div class="d-flex align-items-center flex-wrap justify-content-center mt-2" style="gap:2px;">`;
    h += `<span class="small text-secondary me-2">${total} ${noun} · page ${page}/${pages}</span>`;
    h += btn('&laquo;', 1, page === 1) + btn('&lsaquo;', page - 1, page === 1);
    for (let p = from; p <= to; p++) h += btn(String(p), p, false, p === page);
    h += btn('&rsaquo;', page + 1, page === pages) + btn('&raquo;', pages, page === pages);
    return h + `</div>`;
  }
  const paginate = {
    slice(items, pageSize, page) {
      if (!Array.isArray(items)) return [];
      if (pageSize <= 0) return items;
      const start = Math.max(0, (page - 1) * pageSize);
      return items.slice(start, start + pageSize);
    },
    totalPages(totalItems, pageSize) {
      if (pageSize <= 0 || totalItems <= 0) return 1;
      return Math.max(1, Math.ceil(totalItems / pageSize));
    },
    render(container, totalItems, pageSize, page, onChange) {
      if (!container) return;
      const total = this.totalPages(totalItems, pageSize);
      if (total <= 1) { container.innerHTML = ''; return; }
      const cur = Math.min(Math.max(1, page), total);
      const btn = (label, target, disabled, isCurrent) =>
        `<button class="btn btn-sm ${isCurrent ? 'btn-primary' : 'btn-outline-secondary'} mx-1"`
        + (disabled ? ' disabled' : '')
        + (target != null ? ` data-pg="${target}"` : '')
        + `>${label}</button>`;
      const span = 2;
      let from = Math.max(1, cur - span);
      let to   = Math.min(total, cur + span);
      while (to - from < 4 && (from > 1 || to < total)) {
        if (from > 1)  from--;
        else if (to < total) to++;
      }
      let nums = '';
      for (let p = from; p <= to; p++) nums += btn(String(p), p, false, p === cur);
      container.innerHTML =
        `<div class="d-flex justify-content-center align-items-center mt-2 small">` +
        btn('« First',    1,         cur === 1,     false) +
        btn('‹ Prev',     cur - 1,   cur === 1,     false) +
        nums +
        btn('Next ›',     cur + 1,   cur === total, false) +
        btn('Last »',     total,     cur === total, false) +
        `<span class="text-secondary ms-2">${cur} / ${total} (${totalItems} rows)</span>` +
        `</div>`;
      container.onclick = (e) => {
        const b = e.target.closest('button[data-pg]');
        if (!b) return;
        const p = parseInt(b.dataset.pg, 10);
        if (!isNaN(p) && p >= 1 && p <= total && typeof onChange === 'function') {
          onChange(p);
        }
      };
    },
  };
  window.pageSizeFor = pageSizeFor;
  window.pagerHtml = pagerHtml;
  window.paginate = paginate;
})();