/**
 * PDF report generator (queue analytics) using pdfkit.
 *
 * generateQueueReport returns a Buffer containing the binary PDF, ready to
 * be base64-encoded and shipped to the client. All sections handle empty
 * data sets gracefully so a freshly-onboarded clinic still gets a valid PDF.
 */

import PDFDocument from "pdfkit";
import {
  getClinicById,
  getAdvancedAnalytics,
  getConsultationStats,
} from "../db.js";
import { childLogger } from "../_core/logger.js";

const log = childLogger("pdf-report");

// QueueMed medical theme
const COLOR_PRIMARY = "#10b981"; // emerald-500
const COLOR_ACCENT = "#06b6d4"; // cyan-500
const COLOR_TEAL = "#0d9488"; // teal-600
const COLOR_TEXT = "#0f172a"; // slate-900
const COLOR_MUTED = "#64748b"; // slate-500
const COLOR_BORDER = "#e2e8f0"; // slate-200
const COLOR_BG_SOFT = "#f0fdf4"; // green-50

const REASON_LABELS: Record<string, string> = {
  consultation: "Consultation",
  urgence: "Urgence",
  certificat_scolaire: "Certificat scolaire",
  certificat_sportif: "Certificat sportif",
  arret_travail: "Arrêt de travail",
  administratif: "Administratif",
  autre: "Autre",
};

function formatDate(d: Date): string {
  return d.toLocaleDateString("fr-FR", {
    day: "2-digit",
    month: "long",
    year: "numeric",
  });
}

export async function generateQueueReport(
  clinicId: number,
  dateRange: { days: number }
): Promise<Buffer> {
  const days = Math.max(1, Math.min(dateRange.days ?? 30, 365));
  const clinic = await getClinicById(clinicId);
  if (!clinic) throw new Error(`Clinic ${clinicId} introuvable`);

  // Fetch the same data the dashboard renders so the PDF matches the UI.
  const [advanced, consult] = await Promise.all([
    getAdvancedAnalytics(clinic.userId, { days, clinicId }),
    getConsultationStats(clinicId, days),
  ]);

  const now = new Date();
  const since = new Date(now.getTime() - days * 24 * 60 * 60 * 1000);

  const doc = new PDFDocument({
    size: "A4",
    margin: 48,
    info: {
      Title: `QueueMed — Rapport ${clinic.name}`,
      Author: "QueueMed",
      Subject: "Rapport file d'attente",
      Creator: "QueueMed",
    },
  });

  const chunks: Buffer[] = [];
  doc.on("data", (c: Buffer) => chunks.push(c));
  const finished = new Promise<Buffer>((resolve, reject) => {
    doc.on("end", () => resolve(Buffer.concat(chunks)));
    doc.on("error", reject);
  });

  // ─── Header ────────────────────────────────────────────────────────────────
  doc
    .rect(0, 0, doc.page.width, 90)
    .fill(COLOR_PRIMARY);
  doc
    .fillColor("#ffffff")
    .fontSize(22)
    .font("Helvetica-Bold")
    .text("QueueMed — Rapport file d'attente", 48, 28);
  doc
    .fontSize(11)
    .font("Helvetica")
    .fillColor("#ecfeff")
    .text(`Cabinet : ${clinic.name}`, 48, 58);
  doc.text(
    `Période : ${formatDate(since)} → ${formatDate(now)}  (${days} j)`,
    48,
    72
  );

  doc.fillColor(COLOR_TEXT);
  doc.y = 120;
  doc.x = 48;

  // ─── Summary table ─────────────────────────────────────────────────────────
  doc
    .fontSize(14)
    .font("Helvetica-Bold")
    .fillColor(COLOR_TEAL)
    .text("Résumé", { underline: false });
  doc.moveDown(0.4);

  const totalJoined = advanced.totalJoined;
  const totalServed = advanced.totalServed;
  const totalAbsent = advanced.totalAbsent;
  const noShowPct = Math.round((advanced.noShowRate ?? 0) * 100);
  const totalConsults = consult.totalConsultations;
  const avgConsultMin = consult.avgDurationMinutes;
  const presenceRate = consult.presenceRate;

  // Compute average wait from byHour aggregates is not direct — use avgWaitByDay
  const allDays = advanced.avgWaitByDay;
  const totalWait = allDays.reduce(
    (acc, d) => acc + d.avgWaitMinutes * d.count,
    0
  );
  const totalWaitCount = allDays.reduce((acc, d) => acc + d.count, 0);
  const avgWaitMin = totalWaitCount > 0 ? Math.round(totalWait / totalWaitCount) : 0;

  const summaryRows: Array<[string, string]> = [
    ["Patients inscrits", String(totalJoined)],
    ["Patients servis", String(totalServed)],
    ["Patients absents", String(totalAbsent)],
    ["Taux d'absence", `${noShowPct}%`],
    ["Taux de présence", `${presenceRate}%`],
    ["Attente moyenne", `${avgWaitMin} min`],
    ["Consultations terminées", String(totalConsults)],
    ["Durée moy. consultation", `${avgConsultMin} min`],
  ];

  drawKeyValueTable(doc, summaryRows);

  doc.moveDown(1);

  // ─── By-hour breakdown ─────────────────────────────────────────────────────
  doc
    .fontSize(14)
    .font("Helvetica-Bold")
    .fillColor(COLOR_TEAL)
    .text("Affluence par heure");
  doc.moveDown(0.4);

  const hourRows = advanced.byHour
    .map((count, hour) => ({ hour, count }))
    .filter((r) => r.count > 0);

  if (hourRows.length === 0) {
    doc
      .fontSize(10)
      .font("Helvetica-Oblique")
      .fillColor(COLOR_MUTED)
      .text("Aucune donnée d'affluence sur la période.");
  } else {
    const maxCount = Math.max(...hourRows.map((r) => r.count));
    drawTableHeader(doc, ["Heure", "Patients", "Répartition"], [80, 80, 320]);
    for (const r of hourRows) {
      ensureSpace(doc, 22);
      const y = doc.y;
      doc
        .font("Helvetica")
        .fontSize(10)
        .fillColor(COLOR_TEXT)
        .text(`${r.hour.toString().padStart(2, "0")}h`, 48, y, { width: 80 });
      doc.text(String(r.count), 128, y, { width: 80 });
      // Bar
      const barX = 208;
      const barMaxW = 300;
      const barW = Math.max(4, Math.round((r.count / maxCount) * barMaxW));
      doc.rect(barX, y + 3, barW, 8).fill(COLOR_PRIMARY);
      doc.fillColor(COLOR_TEXT);
      doc.y = y + 18;
    }
  }

  doc.moveDown(1);

  // ─── Top visit reasons ─────────────────────────────────────────────────────
  doc
    .fontSize(14)
    .font("Helvetica-Bold")
    .fillColor(COLOR_TEAL)
    .text("Motifs de consultation");
  doc.moveDown(0.4);

  if (consult.topReasons.length === 0) {
    doc
      .fontSize(10)
      .font("Helvetica-Oblique")
      .fillColor(COLOR_MUTED)
      .text("Aucun motif de consultation enregistré.");
  } else {
    drawTableHeader(doc, ["Motif", "Nombre", "Part"], [240, 80, 120]);
    const topTotal = consult.topReasons.reduce((s, r) => s + r.count, 0);
    for (const r of consult.topReasons) {
      ensureSpace(doc, 18);
      const y = doc.y;
      const label = REASON_LABELS[r.reason] ?? r.reason;
      const pct = topTotal > 0 ? Math.round((r.count / topTotal) * 100) : 0;
      doc
        .font("Helvetica")
        .fontSize(10)
        .fillColor(COLOR_TEXT)
        .text(label, 48, y, { width: 240 });
      doc.text(String(r.count), 288, y, { width: 80 });
      doc.text(`${pct}%`, 368, y, { width: 120 });
      doc.y = y + 16;
    }
  }

  // ─── Footer ────────────────────────────────────────────────────────────────
  const footerY = doc.page.height - 36;
  doc
    .fontSize(9)
    .font("Helvetica")
    .fillColor(COLOR_MUTED)
    .text(
      `Généré par QueueMed le ${now.toLocaleString("fr-FR")}`,
      48,
      footerY,
      { align: "center", width: doc.page.width - 96 }
    );

  doc.end();

  try {
    return await finished;
  } catch (err) {
    log.error({ err, clinicId }, "PDF generation failed");
    throw err;
  }
}

// ─── Helpers ─────────────────────────────────────────────────────────────────
function ensureSpace(doc: PDFKit.PDFDocument, needed: number): void {
  if (doc.y + needed > doc.page.height - 60) {
    doc.addPage();
  }
}

function drawKeyValueTable(
  doc: PDFKit.PDFDocument,
  rows: Array<[string, string]>
): void {
  const colKeyW = 260;
  const colValW = 240;
  const x = 48;
  for (const [k, v] of rows) {
    ensureSpace(doc, 22);
    const y = doc.y;
    doc
      .rect(x, y, colKeyW + colValW, 20)
      .fill(COLOR_BG_SOFT)
      .stroke(COLOR_BORDER);
    doc
      .font("Helvetica")
      .fontSize(10)
      .fillColor(COLOR_TEXT)
      .text(k, x + 8, y + 6, { width: colKeyW - 16 });
    doc
      .font("Helvetica-Bold")
      .fillColor(COLOR_TEAL)
      .text(v, x + colKeyW, y + 6, { width: colValW - 8, align: "right" });
    doc.y = y + 22;
  }
  doc.fillColor(COLOR_TEXT);
}

function drawTableHeader(
  doc: PDFKit.PDFDocument,
  headers: string[],
  widths: number[]
): void {
  ensureSpace(doc, 22);
  const x = 48;
  const y = doc.y;
  doc.rect(x, y, widths.reduce((a, b) => a + b, 0), 20).fill(COLOR_PRIMARY);
  let cx = x;
  for (let i = 0; i < headers.length; i++) {
    doc
      .font("Helvetica-Bold")
      .fontSize(10)
      .fillColor("#ffffff")
      .text(headers[i], cx + 8, y + 6, { width: widths[i] - 16 });
    cx += widths[i];
  }
  doc.fillColor(COLOR_TEXT);
  doc.y = y + 22;
}