/**
 * image-pages.js - helpers shared by the GE Aerospace image tabs.
 * Loaded by templates/_image_header.html. Exposes window.PxeImage:
 *
 *   PxeImage.postJSON(url, body)   POST JSON with the CSRF header;
 *                                  resolves {ok, status, data}.
 *   PxeImage.renderDiff(el, files) draw [{name, changed, diff, reformat}]
 *                                  (services/control_files.public) into el.
 *   PxeImage.reviewAndSave(opts)   preview -> diff modal -> save -> reload.
 *        opts: previewUrl, saveUrl, body (object), title (optional),
 *              onSaved(data) (optional; default reloads the page).
 */
(function () {
  'use strict';

  function csrfToken() {
    var m = document.querySelector('meta[name="csrf-token"]');
    return m ? m.getAttribute('content') : '';
  }

  function postJSON(url, body) {
    return fetch(url, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json', 'X-CSRF-Token': csrfToken() },
      body: JSON.stringify(body || {}),
      credentials: 'same-origin'
    }).then(function (resp) {
      return resp.json().catch(function () { return { error: 'HTTP ' + resp.status }; })
        .then(function (data) { return { ok: resp.ok, status: resp.status, data: data }; });
    });
  }

  function el(tag, cls, text) {
    var e = document.createElement(tag);
    if (cls) e.className = cls;
    if (text !== undefined) e.textContent = text;
    return e;
  }

  function renderDiff(container, files) {
    container.innerHTML = '';
    var changed = (files || []).filter(function (f) { return f.changed; });
    if (!changed.length) {
      container.appendChild(el('div', 'alert alert-info mb-0', 'No changes: the files already hold exactly this.'));
      return 0;
    }
    changed.forEach(function (f) {
      var box = el('div', 'diff-file');
      var head = el('div', 'diff-file-head');
      head.appendChild(el('i', 'bi bi-file-earmark-diff'));
      head.appendChild(el('span', 'mono', f.name));
      if (!f.existed) head.appendChild(el('span', 'badge badge-info', 'new file'));
      if (f.reformat) {
        var w = el('span', 'badge badge-warning', 'whitespace also changes');
        w.title = 'The current file is not laid out the way it will be written; ' +
          'unchanged lines may show as changed.';
        head.appendChild(w);
      }
      box.appendChild(head);
      var pre = el('pre', 'diff-view');
      String(f.diff || '').split('\n').forEach(function (line, i, all) {
        if (i === all.length - 1 && line === '') return;
        var c = '';
        if (line.indexOf('+++') === 0 || line.indexOf('---') === 0) c = 'd-meta';
        else if (line.indexOf('@@') === 0) c = 'd-hunk';
        else if (line.charAt(0) === '+') c = 'd-add';
        else if (line.charAt(0) === '-') c = 'd-del';
        pre.appendChild(el('span', c, line || ' '));
      });
      box.appendChild(pre);
      container.appendChild(box);
    });
    return changed.length;
  }

  function reviewAndSave(opts) {
    var modalEl = document.getElementById('imageReviewModal');
    var body = document.getElementById('imageReviewBody');
    var err = document.getElementById('imageReviewError');
    var confirmBtn = document.getElementById('imageReviewConfirm');
    var title = document.getElementById('imageReviewTitle');
    if (!modalEl || !window.bootstrap) return;
    title.textContent = opts.title || 'Review changes';
    body.innerHTML = '<div class="text-muted py-3">Building the preview...</div>';
    err.classList.add('d-none');
    confirmBtn.disabled = true;
    var modal = bootstrap.Modal.getOrCreateInstance(modalEl);
    modal.show();

    function fail(msg) {
      err.textContent = msg;
      err.classList.remove('d-none');
    }

    postJSON(opts.previewUrl, opts.body).then(function (r) {
      if (!r.ok) { body.innerHTML = ''; fail(r.data.error || 'Preview failed.'); return; }
      var n = renderDiff(body, r.data.files);
      var expect = {};
      (r.data.files || []).forEach(function (f) { expect[f.name] = f.sha_before; });
      confirmBtn.disabled = n === 0;
      confirmBtn.onclick = function () {
        confirmBtn.disabled = true;
        var payload = Object.assign({}, opts.body, { expect: expect });
        postJSON(opts.saveUrl, payload).then(function (s) {
          if (!s.ok) { fail(s.data.error || 'Save failed.'); confirmBtn.disabled = false; return; }
          if (opts.onSaved) opts.onSaved(s.data);
          else window.location.reload();
        }).catch(function (e) { fail('Save failed: ' + e); confirmBtn.disabled = false; });
      };
    }).catch(function (e) { body.innerHTML = ''; fail('Preview failed: ' + e); });
  }

  window.PxeImage = { postJSON: postJSON, renderDiff: renderDiff, reviewAndSave: reviewAndSave };
})();