// ── Database Explorer Page ──

registerPage('db-explorer', {
  async init() {
    if (!currentUser || !currentUser.isAdmin) {
      navigateTo('dashboard');
      return;
    }

    var titleEl = document.getElementById('dbExplorerTitle');
    var contentEl = document.getElementById('dbExplorerContent');
    var currentTable = null;

    await loadTables();

    async function loadTables() {
      currentTable = null;
      titleEl.textContent = 'Datenbank-Explorer';

      try {
        var resp = await fetch('/api/admin/db/tables');
        var data = await resp.json();

        contentEl.innerHTML = '';
        var table = document.createElement('table');
        table.className = 'db-table';

        var thead = document.createElement('thead');
        thead.innerHTML = '<tr><th>Tabelle</th><th>Spalten</th><th>Zeilen</th></tr>';
        table.appendChild(thead);

        var tbody = document.createElement('tbody');
        data.tables.forEach(function(t) {
          var tr = document.createElement('tr');
          tr.className = 'db-table-row clickable';

          var tdName = document.createElement('td');
          tdName.innerHTML = '<i class="fa fa-table"></i> ' + esc(t.name);
          tdName.className = 'db-table-name';

          var tdCols = document.createElement('td');
          tdCols.textContent = t.columns;
          tdCols.className = 'db-table-num';

          var tdRows = document.createElement('td');
          tdRows.textContent = t.rows.toLocaleString();
          tdRows.className = 'db-table-num';

          tr.appendChild(tdName);
          tr.appendChild(tdCols);
          tr.appendChild(tdRows);

          tr.addEventListener('click', function() {
            loadTableData(t.name, -1);
          });

          tbody.appendChild(tr);
        });

        table.appendChild(tbody);
        contentEl.appendChild(table);
      } catch (err) {
        contentEl.innerHTML = '<p class="error">Fehler beim Laden: ' + esc(err.message) + '</p>';
      }
    }

    async function loadTableData(name, page) {
      currentTable = name;
      titleEl.innerHTML = '<span class="db-back-link">Datenbank-Explorer</span> <i class="fa fa-chevron-right chevron-separator"></i> ' + esc(name);

      // Back-Link klickbar
      titleEl.querySelector('.db-back-link').classList.add('clickable');
      titleEl.querySelector('.db-back-link').addEventListener('click', function() {
        loadTables();
      });

      try {
        var resp = await fetch('/api/admin/db/tables/' + encodeURIComponent(name) + '?page=' + page + '&pageSize=1000');
        var data = await resp.json();
        page = data.pagination.page;

        contentEl.innerHTML = '';

        // Info-Zeile
        var info = document.createElement('div');
        info.className = 'db-info-bar';
        info.innerHTML = '<span>' + data.pagination.totalRows.toLocaleString() + ' Zeilen</span>';

        // Pagination
        if (data.pagination.totalPages > 1) {
          var pagDiv = document.createElement('span');
          pagDiv.className = 'db-pagination';

          if (page > 1) {
            var prevBtn = document.createElement('button');
            prevBtn.className = 'btn btn-small';
            prevBtn.innerHTML = '<i class="fa fa-chevron-left"></i>';
            prevBtn.addEventListener('click', function() { loadTableData(name, page - 1); });
            pagDiv.appendChild(prevBtn);
          }

          var pageInfo = document.createElement('span');
          pageInfo.className = 'db-page-info';
          pageInfo.textContent = 'Seite ' + page + ' / ' + data.pagination.totalPages;
          pagDiv.appendChild(pageInfo);

          if (page < data.pagination.totalPages) {
            var nextBtn = document.createElement('button');
            nextBtn.className = 'btn btn-small';
            nextBtn.innerHTML = '<i class="fa fa-chevron-right"></i>';
            nextBtn.addEventListener('click', function() { loadTableData(name, page + 1); });
            pagDiv.appendChild(nextBtn);
          }

          info.appendChild(pagDiv);
        }

        contentEl.appendChild(info);

        // Tabelle mit Daten
        var wrapper = document.createElement('div');
        wrapper.className = 'db-table-wrapper';

        var table = document.createElement('table');
        table.className = 'db-table db-data-table';

        // Header aus Spalten-Info
        var thead = document.createElement('thead');
        var headerRow = document.createElement('tr');
        data.columns.forEach(function(col) {
          var th = document.createElement('th');
          th.textContent = col.name;
          if (col.pk) th.innerHTML += ' <i class="fa fa-key icon-dim-sm"></i>';
          th.title = col.type + (col.notnull ? ' NOT NULL' : '') + (col.pk ? ' PRIMARY KEY' : '');
          headerRow.appendChild(th);
        });
        thead.appendChild(headerRow);
        table.appendChild(thead);

        // Body
        var tbody = document.createElement('tbody');
        if (data.rows.length === 0) {
          var emptyRow = document.createElement('tr');
          var emptyCell = document.createElement('td');
          emptyCell.colSpan = data.columns.length;
          emptyCell.className = 'db-empty';
          emptyCell.textContent = 'Keine Daten';
          emptyRow.appendChild(emptyCell);
          tbody.appendChild(emptyRow);
        } else {
          data.rows.forEach(function(row) {
            var tr = document.createElement('tr');
            data.columns.forEach(function(col) {
              var td = document.createElement('td');
              var val = row[col.name];
              if (val === null || val === undefined) {
                td.innerHTML = '<span class="db-null">NULL</span>';
              } else {
                var str = String(val);
                if (str.length > 120) {
                  td.textContent = str.substring(0, 120) + '…';
                  td.title = str;
                } else {
                  td.textContent = str;
                }
              }
              tr.appendChild(td);
            });
            tbody.appendChild(tr);
          });
        }

        table.appendChild(tbody);
        wrapper.appendChild(table);
        contentEl.appendChild(wrapper);
      } catch (err) {
        contentEl.innerHTML = '<p class="error">Fehler beim Laden: ' + esc(err.message) + '</p>';
      }
    }
  },

  destroy() {}
});