const PDFDocument = require('pdfkit');
const ExcelJS = require('exceljs');
const fs = require('fs');
const path = require('path');
const { sendMail, emailWrapper } = require('../utils/email');

function a4Doc(orientation = 'portrait') {
  return new PDFDocument({ size: 'A4', margin: 20, layout: orientation === 'landscape' ? 'landscape' : 'portrait' });
}

// Brand palette — mirrors the web reports' indigo theme and the dataviz-skill categorical
// palette used by the on-screen HorizontalBarChart, so exported PDFs/Excel look like the
// same report instead of a plain data dump.
const BRAND = '#4f46e5';
const BRAND_DARK = '#3730a3';
const BRAND_LIGHT = '#eef2ff';
const TEXT_DARK = '#111827';
const TEXT_MUTED = '#6b7280';
const BORDER = '#e5e7eb';
const TONE_COLORS = {
  green: { bg: '#ecfdf5', accent: '#059669' },
  blue: { bg: '#eff6ff', accent: '#2563eb' },
  violet: { bg: '#f5f3ff', accent: '#7c3aed' },
  amber: { bg: '#fffbeb', accent: '#d97706' },
  rose: { bg: '#fff1f2', accent: '#e11d48' },
  gray: { bg: '#f3f4f6', accent: '#4b5563' },
};
const CATEGORICAL_COLORS = ['#2a78d6', '#eb6834', '#1baf7a', '#eda100', '#e87ba4', '#4a3aa7', '#e34948'];

function isEmphasisRow(firstCell) {
  const s = String(firstCell ?? '').trim();
  return /^total$/i.test(s) || /net profit/i.test(s) || /unassigned donations/i.test(s) || /revenue per ticket/i.test(s);
}

function drawHeader(doc, title, subtitle) {
  const pageWidth = doc.page.width - doc.page.margins.left - doc.page.margins.right;
  const x = doc.page.margins.left;
  const y = doc.page.margins.top;
  const h = subtitle ? 46 : 32;
  doc.save();
  doc.roundedRect(x, y, pageWidth, h, 6).fill(BRAND);
  doc.fillColor('#ffffff').font('Helvetica-Bold').fontSize(16).text(title || 'Report', x + 14, y + 9, { width: pageWidth - 28 });
  if (subtitle) {
    doc.font('Helvetica').fontSize(9).fillColor('#e0e7ff').text(subtitle, x + 14, y + 30, { width: pageWidth - 28 });
  }
  doc.restore();
  doc.y = y + h + 14;
}

function drawStats(doc, stats) {
  if (!Array.isArray(stats) || stats.length === 0) return;
  const pageWidth = doc.page.width - doc.page.margins.left - doc.page.margins.right;
  const perRow = Math.max(1, Math.min(5, Math.floor(pageWidth / 110)));
  const gap = 8;
  const boxW = (pageWidth - gap * (perRow - 1)) / perRow;
  const boxH = 34;
  let rowY = doc.y;
  stats.forEach((s, i) => {
    const col = i % perRow;
    if (col === 0 && i !== 0) rowY += boxH + gap;
    const bx = doc.page.margins.left + col * (boxW + gap);
    const tone = TONE_COLORS[s.tone] || TONE_COLORS.gray;
    doc.save();
    doc.roundedRect(bx, rowY, boxW, boxH, 5).fill(tone.bg);
    doc.fillColor(TEXT_MUTED).font('Helvetica').fontSize(7.5).text(String(s.label || ''), bx + 8, rowY + 6, { width: boxW - 16 });
    doc.fillColor(tone.accent).font('Helvetica-Bold').fontSize(11).text(String(s.value || ''), bx + 8, rowY + 17, { width: boxW - 16 });
    doc.restore();
  });
  doc.y = rowY + boxH + 16;
  if (doc.y > doc.page.height - 60) doc.addPage();
}

function drawChart(doc, chart) {
  if (!chart || !Array.isArray(chart.data) || chart.data.length === 0) return;
  const pageWidth = doc.page.width - doc.page.margins.left - doc.page.margins.right;
  const x = doc.page.margins.left;
  if (chart.title) {
    doc.fillColor(TEXT_MUTED).font('Helvetica-Bold').fontSize(9).text(chart.title, x, doc.y);
    doc.moveDown(0.4);
  }
  const labelW = 110;
  const valueW = 80;
  const barAreaW = pageWidth - labelW - valueW - 16;
  const max = Math.max(1, ...chart.data.map(d => Math.abs(d.value || 0)));
  const rowH = 16;
  chart.data.forEach((d, i) => {
    const y = doc.y;
    doc.fillColor(TEXT_DARK).font('Helvetica').fontSize(8).text(String(d.label || ''), x, y + 3, { width: labelW - 8 });
    const trackX = x + labelW;
    doc.roundedRect(trackX, y + 2, barAreaW, 8, 4).fill('#f3f4f6');
    const w = Math.max(4, (Math.abs(d.value || 0) / max) * barAreaW);
    doc.roundedRect(trackX, y + 2, w, 8, 4).fill(CATEGORICAL_COLORS[i % CATEGORICAL_COLORS.length]);
    doc.fillColor(TEXT_DARK).font('Helvetica').fontSize(8).text(d.displayValue != null ? String(d.displayValue) : String(d.value), trackX + barAreaW + 8, y + 3, { width: valueW - 8, align: 'right' });
    doc.y = y + rowH;
    if (doc.y > doc.page.height - 60) doc.addPage();
  });
  doc.moveDown(0.8);
}

function drawNote(doc, note) {
  if (!note) return;
  const pageWidth = doc.page.width - doc.page.margins.left - doc.page.margins.right;
  const x = doc.page.margins.left;
  const y = doc.y;
  doc.font('Helvetica-Oblique').fontSize(8.5);
  const h = doc.heightOfString(note, { width: pageWidth - 20 }) + 14;
  doc.save();
  doc.roundedRect(x, y, pageWidth, h, 5).fill('#f9fafb');
  doc.fillColor(TEXT_MUTED).text(note, x + 10, y + 7, { width: pageWidth - 20 });
  doc.restore();
  doc.y = y + h + 12;
  if (doc.y > doc.page.height - 60) doc.addPage();
}

// Draws a single branded table (header band, zebra rows, highlighted total rows) at the
// document's current y — shared by the main table body and any extraTables sections below it.
function drawTable(doc, table) {
  const columns = Array.isArray(table.columns) ? table.columns : [];
  const colCount = columns.length || (table.rows[0] ? table.rows[0].length : 1);
  const pageWidth = doc.page.width - doc.page.margins.left - doc.page.margins.right;
  const baseWidth = Math.floor(pageWidth / Math.max(1, colCount));
  const colWidths = new Array(colCount).fill(baseWidth);
  if (colCount > 0) colWidths[0] = Math.floor(baseWidth * 1.2);

  // Header band
  if (columns.length) {
    let x = doc.page.margins.left;
    const y = doc.y;
    doc.save();
    doc.rect(x, y, pageWidth, 22).fill(BRAND_LIGHT);
    doc.fillColor(BRAND_DARK).font('Helvetica-Bold').fontSize(10.5);
    columns.forEach((h, i) => {
      const w = colWidths[i] || baseWidth;
      doc.text(String(h || ''), x + 6, y + 6, { width: w - 12 });
      x += w;
    });
    doc.restore();
    doc.moveDown(1.6);
  }

  // Rows — zebra striped, with a highlighted tint+bold for total/summary rows
  const rows = table.rows;
  rows.forEach((row) => {
    const emphasis = isEmphasisRow(row[0]);
    const rowY = doc.y;
    const rowH = 18;
    const bg = emphasis ? BRAND_LIGHT : (rows.indexOf(row) % 2 === 0 ? '#ffffff' : '#f9fafb');
    doc.save();
    doc.rect(doc.page.margins.left, rowY - 2, pageWidth, rowH + 4).fill(bg).restore();
    let x = doc.page.margins.left;
    row.forEach((cell, i) => {
      const w = colWidths[i] || baseWidth;
      doc.fillColor(emphasis ? BRAND_DARK : TEXT_DARK).font(emphasis ? 'Helvetica-Bold' : 'Helvetica').fontSize(9.5).text(String(cell ?? ''), x + 6, rowY, { width: w - 12 });
      doc.strokeColor(BORDER).lineWidth(0.5).moveTo(x, rowY - 2).lineTo(x, rowY + rowH + 2).stroke();
      x += w;
    });
    doc.strokeColor(BORDER).lineWidth(0.5).moveTo(doc.page.margins.left + pageWidth, rowY - 2).lineTo(doc.page.margins.left + pageWidth, rowY + rowH + 2).stroke();
    doc.moveDown(1.1);
    if (doc.y > doc.page.height - 40) {
      doc.addPage();
    }
  });
  doc.strokeColor(BORDER).lineWidth(0.5).moveTo(doc.page.margins.left, doc.y).lineTo(doc.page.margins.left + pageWidth, doc.y).stroke();
  doc.moveDown(1);
}

// Shared drawing logic for all PDF-producing endpoints (download, email, WhatsApp) — draws a
// branded header, optional stat tiles / bar chart / note, then a 'table' or 'layered' body
// (plus any extraTables sections below it) onto whatever PDFDocument the caller gives it
// (streamed straight to the HTTP response for download, or to a temp file for email/WhatsApp).
function drawReportPdf(doc, { title, subtitle, kind, table, layered, stats, chart, note, extraTables }) {
  drawHeader(doc, title, subtitle);
  drawStats(doc, stats);
  drawChart(doc, chart);
  drawNote(doc, note);

  // Path-drawing ops (rect/moveTo/lineTo, used throughout drawTable's borders) leave PDFKit's
  // implicit text cursor (doc.x) at the last point drawn rather than the left margin, so every
  // text() call below passes an explicit x — relying on the implicit cursor after a table has
  // rendered puts the next label at the table's right edge instead of the margin.
  const leftX = doc.page.margins.left;

  if (kind === 'table' && table && Array.isArray(table.rows)) {
    drawTable(doc, table);
  } else if (kind === 'layered' && layered && Array.isArray(layered.sections)) {
    if (layered.header) {
      doc.font('Helvetica-Bold').fontSize(13).fillColor(TEXT_DARK).text(layered.header, leftX, doc.y);
      doc.moveDown(0.3);
    }
    doc.font('Helvetica').fontSize(11);
    for (const section of layered.sections) {
      doc.fillColor(BRAND_DARK).font('Helvetica-Bold').text(String(section.title || ''), leftX, doc.y, { continued: false });
      doc.moveDown(0.15);
      doc.font('Helvetica').fontSize(10);
      if (Array.isArray(section.items) && section.items.length) {
        for (const item of section.items) {
          doc.circle(doc.page.margins.left + 2, doc.y + 6, 1.5).fill(BRAND).stroke();
          doc.fillColor(TEXT_DARK);
          doc.text('  ' + String(item || ''), doc.page.margins.left + 8, doc.y, { width: doc.page.width - doc.page.margins.left - doc.page.margins.right - 8 });
          doc.moveDown(0.2);
        }
      } else {
        doc.fillColor(TEXT_MUTED).text('No items', leftX, doc.y);
      }
      doc.moveDown(0.5);
      if (doc.y > doc.page.height - 60) doc.addPage();
    }
  } else {
    doc.fillColor(TEXT_MUTED).font('Helvetica').text('No content', leftX, doc.y);
  }

  if (Array.isArray(extraTables)) {
    extraTables.forEach(t => {
      if (!t || !Array.isArray(t.rows) || t.rows.length === 0) return;
      if (doc.y > doc.page.height - 100) doc.addPage();
      doc.moveDown(0.6);
      if (t.title) {
        doc.fillColor(BRAND_DARK).font('Helvetica-Bold').fontSize(11).text(t.title, leftX, doc.y);
        doc.moveDown(0.4);
      }
      drawTable(doc, t);
    });
  }
}

// Renders payload to a temp PDF file and returns its path — shared by emailPdf and whatsappPdf.
async function renderReportPdfToFile(payload) {
  const tempDir = path.join(__dirname, '..', '..', 'temp');
  if (!fs.existsSync(tempDir)) fs.mkdirSync(tempDir, { recursive: true });
  const filePath = path.join(tempDir, `${(payload.title || 'report')}-${Date.now()}.pdf`.replace(/[^a-z0-9_.-]/gi, '_'));

  await new Promise((resolve, reject) => {
    const doc = a4Doc(payload.orientation === 'landscape' ? 'landscape' : 'portrait');
    const ws = fs.createWriteStream(filePath);
    doc.pipe(ws);
    drawReportPdf(doc, payload);
    doc.end();
    ws.on('finish', resolve);
    ws.on('error', reject);
  });

  return filePath;
}

// Builds a styled .xlsx workbook mirroring the same payload shape used for PDF — branded
// title band, stat label/value rows, a chart rendered as a mini-table with a native Excel
// data-bar conditional format (the closest free/no-extra-viz-dependency equivalent of the
// web's bar chart), then the main table with a bold colored header row and highlighted
// total rows.
async function buildReportWorkbook(payload) {
  const { title, subtitle, kind, table, layered, stats, chart, note, extraTables } = payload || {};
  const wb = new ExcelJS.Workbook();
  const orgName = require('../utils/settingsCache').getSettingSync('org_name', process.env.ORG_NAME || 'Cross Code');
  wb.creator = `${orgName} Events`;
  wb.created = new Date();
  const sheetName = (title || 'Report').replace(/[\\/*?:[\]]/g, ' ').slice(0, 31) || 'Report';
  const ws = wb.addWorksheet(sheetName);

  const colCount = Math.max(4, (table?.columns?.length || 0));
  let r = 1;

  ws.mergeCells(r, 1, r, colCount);
  const titleCell = ws.getCell(r, 1);
  titleCell.value = title || 'Report';
  titleCell.font = { bold: true, size: 16, color: { argb: 'FFFFFFFF' } };
  titleCell.fill = { type: 'pattern', pattern: 'solid', fgColor: { argb: 'FF4F46E5' } };
  titleCell.alignment = { vertical: 'middle' };
  ws.getRow(r).height = 26;
  r++;

  if (subtitle) {
    ws.mergeCells(r, 1, r, colCount);
    const subCell = ws.getCell(r, 1);
    subCell.value = subtitle;
    subCell.font = { italic: true, size: 10, color: { argb: 'FF6B7280' } };
    r++;
  }
  r++;

  if (Array.isArray(stats) && stats.length) {
    stats.forEach(s => {
      ws.getCell(r, 1).value = s.label;
      ws.getCell(r, 1).font = { color: { argb: 'FF6B7280' }, size: 10 };
      ws.getCell(r, 2).value = s.value;
      ws.getCell(r, 2).font = { bold: true, size: 11 };
      r++;
    });
    r++;
  }

  if (chart && Array.isArray(chart.data) && chart.data.length) {
    if (chart.title) {
      ws.getCell(r, 1).value = chart.title;
      ws.getCell(r, 1).font = { bold: true, size: 10 };
      r++;
    }
    const chartStartRow = r;
    chart.data.forEach(d => {
      ws.getCell(r, 1).value = d.label;
      ws.getCell(r, 2).value = typeof d.value === 'number' ? d.value : Number(d.value) || 0;
      r++;
    });
    ws.addConditionalFormatting({
      ref: `B${chartStartRow}:B${r - 1}`,
      rules: [{ type: 'dataBar', cfvo: [{ type: 'min' }, { type: 'max' }], color: { argb: 'FF2A78D6' } }]
    });
    r++;
  }

  if (note) {
    ws.mergeCells(r, 1, r, colCount);
    ws.getCell(r, 1).value = note;
    ws.getCell(r, 1).font = { italic: true, size: 9, color: { argb: 'FF6B7280' } };
    ws.getCell(r, 1).alignment = { wrapText: true };
    r += 2;
  }

  if (kind === 'table' && table && Array.isArray(table.rows)) {
    const columns = table.columns || [];
    const { nextRow, dataStartRow } = writeTableRows(ws, r, columns, table.rows);
    ws.views = [{ state: 'frozen', ySplit: dataStartRow - 1 }];
    r = nextRow;
  } else if (kind === 'layered' && layered && Array.isArray(layered.sections)) {
    if (layered.header) {
      ws.getCell(r, 1).value = layered.header;
      ws.getCell(r, 1).font = { bold: true, size: 12 };
      r += 2;
    }
    layered.sections.forEach(section => {
      ws.getCell(r, 1).value = section.title;
      ws.getCell(r, 1).font = { bold: true, color: { argb: 'FF3730A3' } };
      r++;
      (section.items || []).forEach(item => {
        ws.getCell(r, 1).value = `• ${item}`;
        r++;
      });
      r++;
    });
    ws.getColumn(1).width = 90;
  }

  if (Array.isArray(extraTables)) {
    extraTables.forEach(t => {
      if (!t || !Array.isArray(t.rows) || t.rows.length === 0) return;
      r++;
      if (t.title) {
        ws.getCell(r, 1).value = t.title;
        ws.getCell(r, 1).font = { bold: true, size: 12, color: { argb: 'FF3730A3' } };
        r++;
      }
      const { nextRow } = writeTableRows(ws, r, t.columns || [], t.rows);
      r = nextRow;
    });
  }

  return wb;
}

// Writes a header row (bold, colored fill) + zebra/emphasis-highlighted data rows at the given
// sheet row — shared by the main table and any extraTables sections. Returns the next free row
// and the data's start row (for optional freeze-pane use by the caller).
function writeTableRows(ws, startRow, columns, rows) {
  let r = startRow;
  const headerRow = ws.getRow(r);
  columns.forEach((c, i) => {
    const cell = headerRow.getCell(i + 1);
    cell.value = c;
    cell.font = { bold: true, color: { argb: 'FF3730A3' } };
    cell.fill = { type: 'pattern', pattern: 'solid', fgColor: { argb: 'FFEEF2FF' } };
    cell.border = { bottom: { style: 'thin', color: { argb: 'FFE5E7EB' } } };
  });
  headerRow.commit();
  r++;
  const dataStartRow = r;
  rows.forEach((row, idx) => {
    const excelRow = ws.getRow(r);
    const emphasis = isEmphasisRow(row[0]);
    row.forEach((val, i) => {
      const cell = excelRow.getCell(i + 1);
      cell.value = val === '' ? null : val;
      if (emphasis) {
        cell.font = { bold: true, color: { argb: 'FF3730A3' } };
        cell.fill = { type: 'pattern', pattern: 'solid', fgColor: { argb: 'FFEEF2FF' } };
      } else if (idx % 2 === 1) {
        cell.fill = { type: 'pattern', pattern: 'solid', fgColor: { argb: 'FFF9FAFB' } };
      }
    });
    excelRow.commit();
    r++;
  });
  columns.forEach((c, i) => {
    let maxLen = String(c || '').length;
    rows.forEach(row => { const v = row[i]; if (v != null && v !== '') maxLen = Math.max(maxLen, String(v).length); });
    const col = ws.getColumn(i + 1);
    col.width = Math.max(col.width || 0, Math.min(40, Math.max(10, maxLen + 2)));
  });
  return { nextRow: r, dataStartRow };
}

// POST /api/reports/pdf
// body: { title, subtitle?, kind: 'table'|'layered', table?, layered?, stats?, chart?, note?, orientation? }
const generatePdf = async (req, res) => {
  try {
    const { title, subtitle, kind, table, layered, orientation, stats, chart, note, extraTables } = req.body || {};
    res.setHeader('Content-Type', 'application/pdf');
    const filename = `${(title || 'report').replace(/[^a-z0-9]/gi, '_').toLowerCase()}.pdf`;
    res.setHeader('Content-Disposition', `attachment; filename="${filename}"`);

    const doc = a4Doc(orientation === 'landscape' ? 'landscape' : 'portrait');
    doc.pipe(res);
    drawReportPdf(doc, { title, subtitle, kind, table, layered, stats, chart, note, extraTables });
    doc.end();
  } catch (e) {
    res.status(400).json({ message: e.message });
  }
};

// POST /api/reports/excel
// body: same payload shape as /pdf — used to produce a styled .xlsx mirroring the PDF/web report.
const generateExcel = async (req, res) => {
  try {
    const payload = req.body || {};
    const wb = await buildReportWorkbook(payload);
    const filename = `${(payload.title || 'report').replace(/[^a-z0-9]/gi, '_').toLowerCase()}.xlsx`;
    res.setHeader('Content-Type', 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet');
    res.setHeader('Content-Disposition', `attachment; filename="${filename}"`);
    await wb.xlsx.write(res);
    res.end();
  } catch (e) {
    res.status(400).json({ message: e.message });
  }
};

// POST /api/reports/email
// body: { title, subtitle?, kind, table?, layered?, stats?, chart?, note?, subject?, body? }
const emailPdf = async (req, res) => {
  try {
    const { title, subtitle, kind, table, layered, subject, body, orientation, stats, chart, note, extraTables } = req.body || {};
    const user = req.user;
    if (!user || !user.email) {
      res.status(400);
      throw new Error('User email not available');
    }

    const filePath = await renderReportPdfToFile({ title, subtitle, kind, table, layered, orientation, stats, chart, note, extraTables });

    // Use the shared mail utility (DB-configured SMTP via Admin -> Site Settings, with env
    // fallback) instead of a one-off transporter — a bare `process.env.EMAIL_HOST` transporter
    // ignores that configuration entirely and fails wherever SMTP is only set up via the DB.
    const bodyText = body || 'Please find your report attached.';
    await sendMail({
      to: user.email,
      subject: subject || (title ? `${title} PDF` : 'Report PDF'),
      text: bodyText,
      html: emailWrapper(
        `<p style="margin:0 0 16px 0;color:#374151">${bodyText}</p>` +
        `<p style="margin:0;color:#374151">Your report <strong>${title || 'Report'}</strong> is attached as a PDF.</p>`,
        { preheader: title || 'Report PDF' }
      ),
      attachments: [{ filename: path.basename(filePath), path: filePath, contentType: 'application/pdf' }]
    });

    try { fs.unlinkSync(filePath); } catch {}

    res.json({ message: `Report emailed to ${user.email}` });
  } catch (e) {
    res.status(400).json({ message: e.message });
  }
};

// POST /api/reports/whatsapp
// body: { title, subtitle?, kind, table?, layered?, stats?, chart?, note?, caption? }
// Sends to the current user's own WhatsApp number (same self-service pattern as emailPdf).
const whatsappPdf = async (req, res) => {
  let filePath = null;
  try {
    const { title, subtitle, kind, table, layered, caption, orientation, stats, chart, note, extraTables } = req.body || {};
    const user = req.user;

    const { isValidZAPhone } = require('../utils/whatsapp');
    if (!user || !isValidZAPhone(user.phoneNumber)) {
      res.status(400);
      throw new Error('No valid WhatsApp number on your account. Add one in your profile to use this.');
    }

    filePath = await renderReportPdfToFile({ title, subtitle, kind, table, layered, orientation, stats, chart, note, extraTables });

    const { sendPdf } = require('../utils/whatsapp');
    const filename = `${(title || 'report').replace(/[^a-z0-9]/gi, '_').toLowerCase()}.pdf`;
    await sendPdf(user.phoneNumber, filePath, filename, caption || title || 'Report');

    res.json({ message: `Report sent to your WhatsApp` });
  } catch (e) {
    res.status(400).json({ message: e.message });
  } finally {
    if (filePath) { try { fs.unlinkSync(filePath); } catch {} }
  }
};

module.exports = { generatePdf, generateExcel, emailPdf, whatsappPdf };