import jsPDF from "jspdf";
import { formatDate } from "./format";

const PAGE_W = 612;
const PAGE_H = 792;
const MARGIN = 54;
const CONTENT_W = PAGE_W - MARGIN * 2;

export interface InvoiceLineItem {
  kind: string;
  description: string;
  work_date: string | null;
  quantity: number;
  rate: number;
  amount: number;
  user_name?: string | null;
  user_initials?: string | null;
  billable?: boolean;
}

export interface InvoiceSubsection {
  key: string;
  label: string;
  billable: boolean;
  items: InvoiceLineItem[];
  subtotal: number;
}

export interface InvoiceCaseGroup {
  caseNumber: string;
  caseTitle: string;
  practiceArea?: string | null;
  items: InvoiceLineItem[];
  subtotal: number;
  /** Optional subsections (Billable Fees, Billable Expenses, Non-Billable Fees, Non-Billable Expenses).
   *  When provided, the renderer groups items by subsection with a header and subtotal. */
  subsections?: InvoiceSubsection[];
}

export interface InvoicePdfInput {
  firm: {
    name?: string | null;
    address1?: string | null;
    address2?: string | null;
    city?: string | null;
    state?: string | null;
    postal?: string | null;
    email?: string | null;
    phone?: string | null;
    website?: string | null;
    footerNote?: string | null;
    logoDataUrl?: string | null;
  };
  client: {
    name: string;
    contact?: string | null;
    address1?: string | null;
    address2?: string | null;
    city?: string | null;
    state?: string | null;
    postal?: string | null;
  };
  invoice: {
    number: string;
    issueDate: string;
    dueDate?: string | null;
    status: string;
    notes?: string | null;
    matter?: string | null;
    caseNumber?: string | null;
    terms?: string | null;
  };
  groups: InvoiceCaseGroup[];
  totals: {
    subtotal: number;
    tax: number;
    total: number;
    paid: number;
    balance: number;
    taxRatePct?: number | null;
    feesAndExpenses?: number | null;
    alternateFees?: number | null;
    adjustments?: Array<{ description: string; amount: number }>;
  };
}

const fmtCurrency = (n: number) =>
  new Intl.NumberFormat("en-US", { style: "currency", currency: "USD" }).format(n || 0);

const fmtDateShort = (s: string | null | undefined): string => {
  if (!s) return "—";
  const d = new Date(s);
  if (isNaN(d.getTime())) return "—";
  const mm = String(d.getMonth() + 1).padStart(2, "0");
  const dd = String(d.getDate()).padStart(2, "0");
  const yy = String(d.getFullYear()).slice(-2);
  return `${mm}/${dd}/${yy}`;
};

function setFont(
  pdf: jsPDF,
  opts: { bold?: boolean; italic?: boolean; size?: number; color?: [number, number, number]; family?: "helvetica" | "times" },
) {
  let style: "normal" | "bold" | "italic" | "bolditalic" = "normal";
  if (opts.bold && opts.italic) style = "bolditalic";
  else if (opts.bold) style = "bold";
  else if (opts.italic) style = "italic";
  pdf.setFont(opts.family ?? "helvetica", style);
  pdf.setFontSize(opts.size ?? 10);
  if (opts.color) pdf.setTextColor(...opts.color);
  else pdf.setTextColor(20, 24, 32);
}

function wrap(pdf: jsPDF, text: string, maxWidth: number): string[] {
  if (!text) return [""];
  return pdf.splitTextToSize(text, maxWidth) as string[];
}

function detectImageFormat(dataUrl: string): "PNG" | "JPEG" | "WEBP" {
  const m = /^data:image\/(png|jpe?g|webp)/i.exec(dataUrl);
  if (!m) return "PNG";
  const t = m[1].toLowerCase();
  if (t === "jpg" || t === "jpeg") return "JPEG";
  if (t === "webp") return "WEBP";
  return "PNG";
}

async function imageNaturalSize(dataUrl: string): Promise<{ w: number; h: number } | null> {
  return new Promise((resolve) => {
    const img = new Image();
    img.onload = () => resolve({ w: img.naturalWidth || img.width, h: img.naturalHeight || img.height });
    img.onerror = () => resolve(null);
    img.src = dataUrl;
  });
}

// Palette
const TEXT: [number, number, number] = [30, 38, 56]; // dark navy text
const MUTED: [number, number, number] = [120, 128, 140];
const RULE: [number, number, number] = [228, 232, 238];
const HEADER_BG: [number, number, number] = [243, 245, 248];
const ACCENT: [number, number, number] = [245, 158, 11]; // warm orange (smile)

function drawSmileMark(pdf: jsPDF, cx: number, cy: number, size: number) {
  // Two checkmark ticks + a curved smile underneath, in accent color.
  pdf.setDrawColor(...ACCENT);
  pdf.setLineCap(1); // round
  pdf.setLineJoin(1);

  // Two checkmarks
  pdf.setLineWidth(size * 0.09);
  // first check
  pdf.lines(
    [
      [size * 0.22, size * 0.22],
      [size * 0.42, -size * 0.5],
    ],
    cx - size * 0.55,
    cy - size * 0.05,
  );
  // second check
  pdf.lines(
    [
      [size * 0.22, size * 0.22],
      [size * 0.42, -size * 0.5],
    ],
    cx - size * 0.2,
    cy - size * 0.05,
  );

  // Smile curve (open arc) — approximated with bezier
  pdf.setLineWidth(size * 0.1);
  // Draw using lines() with bezier control points: [cp1x, cp1y, cp2x, cp2y, ex, ey]
  pdf.lines(
    [
      [size * 0.2, size * 0.55, size * 0.7, size * 0.55, size * 0.95, 0],
    ],
    cx - size * 0.5,
    cy + size * 0.2,
    [1, 1],
    "S",
    false,
  );
  // Arrow tip on the right end of smile
  pdf.setLineWidth(size * 0.09);
  pdf.lines(
    [
      [-size * 0.18, -size * 0.05],
      [size * 0.05, size * 0.18],
    ],
    cx + size * 0.45,
    cy + size * 0.2,
  );
}

export async function downloadInvoicePdf(input: InvoicePdfInput, filename: string) {
  const pdf = new jsPDF({ unit: "pt", format: "letter" });

  let y = MARGIN;
  const ensure = (need: number) => {
    if (y + need > PAGE_H - MARGIN - 40) {
      drawPageFooter(pdf, input);
      pdf.addPage();
      y = MARGIN;
    }
  };

  // ===== Top: "Invoice" title (left) + logo or smile mark (right) =====
  setFont(pdf, { bold: true, size: 34, color: TEXT, family: "times" });
  pdf.text("Invoice", MARGIN, y + 28);

  // Right side: firm logo if available, else decorative smile mark
  if (input.firm.logoDataUrl) {
    const MAX_W = 110;
    const MAX_H = 60;
    const size = await imageNaturalSize(input.firm.logoDataUrl);
    let lw = MAX_W;
    let lh = MAX_H;
    if (size && size.w > 0 && size.h > 0) {
      const scale = Math.min(MAX_W / size.w, MAX_H / size.h, 1);
      lw = size.w * scale;
      lh = size.h * scale;
    }
    try {
      pdf.addImage(
        input.firm.logoDataUrl,
        detectImageFormat(input.firm.logoDataUrl),
        PAGE_W - MARGIN - lw,
        y,
        lw,
        lh,
        undefined,
        "FAST",
      );
    } catch {
      drawSmileMark(pdf, PAGE_W - MARGIN - 40, y + 18, 60);
    }
  } else {
    drawSmileMark(pdf, PAGE_W - MARGIN - 40, y + 18, 60);
  }

  y += 70;

  // ===== FROM / TO / Info panel =====
  // Three columns: FROM, TO, and a key-value info card on the right
  const colW = (CONTENT_W - 20) / 3;
  const fromX = MARGIN;
  const toX = MARGIN + colW + 10;
  const infoX = MARGIN + colW * 2 + 20;
  const infoW = CONTENT_W - (colW * 2 + 20);

  // FROM
  setFont(pdf, { bold: true, size: 8, color: MUTED });
  pdf.text("FROM:", fromX, y);
  setFont(pdf, { bold: true, size: 12, color: TEXT });
  pdf.text(input.firm.name || "Firm", fromX, y + 14);
  setFont(pdf, { size: 9, color: TEXT });
  let fy = y + 28;
  const firmLines = [
    input.firm.address1,
    input.firm.address2,
    [input.firm.city, input.firm.state, input.firm.postal].filter(Boolean).join(", "),
    input.firm.phone,
    input.firm.email,
    input.firm.website,
  ].filter((l): l is string => !!l && l.trim().length > 0);
  for (const l of firmLines) {
    pdf.text(l, fromX, fy);
    fy += 11;
  }

  // TO
  setFont(pdf, { bold: true, size: 8, color: MUTED });
  pdf.text("TO:", toX, y);
  setFont(pdf, { bold: true, size: 12, color: TEXT });
  pdf.text(input.client.name, toX, y + 14);
  setFont(pdf, { size: 9, color: TEXT });
  let ty = y + 28;
  const clientLines = [
    input.client.contact,
    input.client.address1,
    input.client.address2,
    [input.client.city, input.client.state, input.client.postal].filter(Boolean).join(", "),
  ].filter((l): l is string => !!l && l.trim().length > 0);
  for (const l of clientLines) {
    pdf.text(l, toX, ty);
    ty += 11;
  }

  // Info card (right) — key/value rows.
  // "Case No." is shown directly under the invoice number for quick reference.
  const infoRows: Array<[string, string]> = [
    ["Inv. Number", input.invoice.number],
  ];
  if (input.invoice.caseNumber) infoRows.push(["Case No.", input.invoice.caseNumber]);
  infoRows.push(["Date of Issue", formatDate(input.invoice.issueDate)]);
  if (input.invoice.terms) infoRows.push(["Terms", input.invoice.terms]);
  if (input.invoice.dueDate) infoRows.push(["Date Due", formatDate(input.invoice.dueDate)]);

  const rowH = 18;
  const infoTop = y - 4;
  const infoH = rowH * infoRows.length;

  // background card
  pdf.setFillColor(...HEADER_BG);
  pdf.rect(infoX, infoTop, infoW, infoH, "F");

  let iy = infoTop + 12;
  infoRows.forEach((row, idx) => {
    setFont(pdf, { size: 9, color: MUTED });
    pdf.text(row[0], infoX + 10, iy);
    setFont(pdf, { size: 9.5, bold: true, color: TEXT });
    const w = pdf.getTextWidth(row[1]);
    pdf.text(row[1], infoX + infoW - 10 - w, iy);
    if (idx < infoRows.length - 1) {
      pdf.setDrawColor(...RULE);
      pdf.setLineWidth(0.5);
      pdf.line(infoX + 10, iy + 6, infoX + infoW - 10, iy + 6);
    }
    iy += rowH;
  });

  y = Math.max(fy, ty, infoTop + infoH) + 24;

  // ===== FEES & EXPENSES section =====
  setFont(pdf, { bold: true, size: 9, color: TEXT });
  pdf.text("FEES & EXPENSES", MARGIN, y);
  y += 10;

  // Column geometry for fees table.
  // Layout (left → right):
  //   DATE | TYPE | DESCRIPTION | QTY | RATE | TAX | TOTAL
  const colDateX = MARGIN + 8;     // date left edge
  const colKindX = MARGIN + 70;    // type label left edge
  const colDescX = MARGIN + 120;   // description left edge
  const colQtyR  = MARGIN + 360;   // qty right edge
  const colRateR = MARGIN + 415;   // rate right edge
  const colTaxR  = MARGIN + 460;   // tax right edge
  const colAmtX  = PAGE_W - MARGIN - 8; // total right edge

  const drawColHeaders = () => {
    pdf.setFillColor(...HEADER_BG);
    pdf.rect(MARGIN, y, CONTENT_W, 22, "F");
    setFont(pdf, { bold: true, size: 8, color: TEXT });
    pdf.text("DATE", colDateX, y + 14);
    pdf.text("TYPE", colKindX, y + 14);
    pdf.text("DESCRIPTION", colDescX, y + 14);
    const qW = pdf.getTextWidth("QTY");
    pdf.text("QTY", colQtyR - qW, y + 14);
    const rW = pdf.getTextWidth("RATE");
    pdf.text("RATE", colRateR - rW, y + 14);
    const tW = pdf.getTextWidth("TAX");
    pdf.text("TAX", colTaxR - tW, y + 14);
    const totW = pdf.getTextWidth("TOTAL");
    pdf.text("TOTAL", colAmtX - totW, y + 14);
    y += 22;
  };

  const drawCaseHeader = (g: InvoiceCaseGroup) => {
    ensure(28);
    pdf.setFillColor(248, 250, 253);
    pdf.rect(MARGIN, y, CONTENT_W, 20, "F");
    setFont(pdf, { bold: true, size: 9.5, color: TEXT });
    const titleText = `${g.caseTitle}`;
    pdf.text(titleText, MARGIN + 8, y + 13);
    setFont(pdf, { size: 8, color: MUTED });
    const meta = [g.caseNumber, g.practiceArea].filter(Boolean).join(" · ");
    if (meta) {
      const metaW = pdf.getTextWidth(meta);
      pdf.text(meta, PAGE_W - MARGIN - 8 - metaW, y + 13);
    }
    y += 20;
    pdf.setDrawColor(...RULE);
    pdf.setLineWidth(0.4);
    pdf.line(MARGIN, y, PAGE_W - MARGIN, y);
  };

  drawColHeaders();

  const taxRate = (input.totals.taxRatePct ?? 0) / 100;
  const multipleCases = input.groups.length > 1;

  const drawSubsectionHeader = (label: string, subtotal: number, billable: boolean) => {
    ensure(22);
    pdf.setFillColor(250, 250, 252);
    pdf.rect(MARGIN, y, CONTENT_W, 16, "F");
    setFont(pdf, { bold: true, size: 8, color: MUTED });
    pdf.text(label.toUpperCase(), MARGIN + 8, y + 11);
    if (billable) {
      const sub = fmtCurrency(subtotal);
      const sw = pdf.getTextWidth(sub);
      setFont(pdf, { bold: true, size: 8, color: TEXT });
      pdf.text(sub, colAmtX - sw, y + 11);
    }
    y += 16;
    pdf.setDrawColor(...RULE);
    pdf.setLineWidth(0.4);
    pdf.line(MARGIN, y, PAGE_W - MARGIN, y);
  };

  const drawItem = (item: InvoiceLineItem) => {
    const isNonBillable = item.billable === false;
    // Reserve generous padding before the QTY column so wrapped text never
    // collides with the right-aligned numeric columns. Measure with the same
    // font (incl. italic for non-billable rows) that will render the text,
    // since italic glyphs are slightly wider than upright ones.
    const descMaxW = colQtyR - colDescX - 24;
    setFont(pdf, { size: 9, color: isNonBillable ? MUTED : TEXT, italic: isNonBillable });
    const descLines = wrap(pdf, item.description || (item.kind === "expense" ? "Expense" : ""), descMaxW);
    const lineHeight = 12;
    const blockH = Math.max(lineHeight * descLines.length + 14, item.user_initials ? 32 : 26);
    ensure(blockH + 4);

    setFont(pdf, { size: 9, color: TEXT });
    pdf.text(fmtDateShort(item.work_date), colDateX, y + 12);
    if (item.user_initials) {
      setFont(pdf, { size: 7.5, color: MUTED });
      pdf.text(item.user_initials, colDateX, y + 23);
    }

    setFont(pdf, { size: 9, color: MUTED });
    const kindLabel =
      item.kind === "expense" ? "Expense" : item.kind === "time" ? "Fee" : item.kind === "manual" ? "Fee" : item.kind;
    pdf.text(kindLabel, colKindX, y + 12);

    setFont(pdf, { size: 9, color: isNonBillable ? MUTED : TEXT, italic: isNonBillable });
    let dy = y + 12;
    for (const dl of descLines) {
      pdf.text(dl, colDescX, dy);
      dy += lineHeight;
    }

    setFont(pdf, { size: 9, color: TEXT });
    const qtyText = item.kind === "expense" ? "—" : Number(item.quantity).toFixed(2);
    const qW = pdf.getTextWidth(qtyText);
    pdf.text(qtyText, colQtyR - qW, y + 12);

    const rateText = fmtCurrency(item.rate);
    const rW = pdf.getTextWidth(rateText);
    pdf.text(rateText, colRateR - rW, y + 12);

    const lineTax = isNonBillable ? 0 : item.amount * taxRate;
    const taxText = fmtCurrency(lineTax);
    const taxW = pdf.getTextWidth(taxText);
    pdf.text(taxText, colTaxR - taxW, y + 12);

    const lineTotal = isNonBillable ? 0 : item.amount + lineTax;
    const amt = isNonBillable ? "—" : fmtCurrency(lineTotal);
    setFont(pdf, { size: 9, bold: true, color: TEXT });
    const aw = pdf.getTextWidth(amt);
    pdf.text(amt, colAmtX - aw, y + 12);

    y += blockH;
    pdf.setDrawColor(...RULE);
    pdf.setLineWidth(0.4);
    pdf.line(MARGIN, y, PAGE_W - MARGIN, y);
  };

  for (const g of input.groups) {
    drawCaseHeader(g);

    // Build subsections: use provided list if any, else a single all-items section.
    const subs: InvoiceSubsection[] =
      g.subsections && g.subsections.length > 0
        ? g.subsections
        : [{ key: "_all", label: "", billable: true, items: g.items, subtotal: g.subtotal }];

    for (const sub of subs) {
      if (sub.label) drawSubsectionHeader(sub.label, sub.subtotal, sub.billable);
      for (const item of sub.items) drawItem(item);
    }

    // Per-case subtotal when there are multiple cases
    if (multipleCases) {
      ensure(22);
      setFont(pdf, { bold: true, size: 9, color: TEXT });
      const label = `Subtotal — ${g.caseNumber}`;
      pdf.text(label, colDescX, y + 14);
      const subText = fmtCurrency(g.subtotal);
      const sw = pdf.getTextWidth(subText);
      pdf.text(subText, colAmtX - sw, y + 14);
      y += 20;
      pdf.setDrawColor(...RULE);
      pdf.setLineWidth(0.6);
      pdf.line(MARGIN, y, PAGE_W - MARGIN, y);
      y += 6;
    }
  }

  y += 20;

  // ===== ADJUSTMENTS section =====
  const adjustments = input.totals.adjustments ?? [];
  if (input.totals.paid > 0 || adjustments.length > 0) {
    ensure(80);
    setFont(pdf, { bold: true, size: 9, color: TEXT });
    pdf.text("ADJUSTMENTS", MARGIN, y);
    y += 10;

    pdf.setFillColor(...HEADER_BG);
    pdf.rect(MARGIN, y, CONTENT_W, 22, "F");
    setFont(pdf, { bold: true, size: 8, color: TEXT });
    pdf.text("DESCRIPTION", colDateX, y + 14);
    const amtH = pdf.getTextWidth("AMOUNT");
    pdf.text("AMOUNT", colAmtX - amtH, y + 14);
    y += 22;

    const drawAdj = (desc: string, amount: number) => {
      ensure(20);
      setFont(pdf, { size: 9, color: TEXT });
      pdf.text(desc, colDateX, y + 12);
      const txt = amount < 0 ? `−${fmtCurrency(Math.abs(amount))}` : fmtCurrency(amount);
      const w = pdf.getTextWidth(txt);
      pdf.text(txt, colAmtX - w, y + 12);
      y += 20;
      pdf.setDrawColor(...RULE);
      pdf.setLineWidth(0.4);
      pdf.line(MARGIN, y, PAGE_W - MARGIN, y);
    };

    for (const a of adjustments) drawAdj(a.description, a.amount);
    if (input.totals.paid > 0) drawAdj("Client Funds Applied", -input.totals.paid);
  }

  // ===== Totals (right-aligned card, no shading, just rules) =====
  ensure(140);
  y += 18;

  const totalsX = PAGE_W - MARGIN - 260;
  const totalsW = 260;

  const drawTotalRow = (
    label: string,
    value: string,
    opts?: { bold?: boolean; size?: number; color?: [number, number, number]; emphasize?: boolean },
  ) => {
    setFont(pdf, { size: opts?.size ?? 10, bold: opts?.bold, color: opts?.color ?? TEXT });
    pdf.text(label, totalsX + 10, y + 12);
    const w = pdf.getTextWidth(value);
    pdf.text(value, totalsX + totalsW - 10 - w, y + 12);
    y += 22;
    pdf.setDrawColor(...RULE);
    pdf.setLineWidth(0.4);
    pdf.line(totalsX, y, totalsX + totalsW, y);
  };

  // Top rule
  pdf.setDrawColor(...RULE);
  pdf.setLineWidth(0.4);
  pdf.line(totalsX, y, totalsX + totalsW, y);

  drawTotalRow("Fees & Expenses", fmtCurrency(input.totals.feesAndExpenses ?? input.totals.subtotal));
  if (input.totals.alternateFees && input.totals.alternateFees > 0) {
    drawTotalRow("Alternate Fees", fmtCurrency(input.totals.alternateFees));
  }
  if (input.totals.tax > 0) {
    const ratePart = input.totals.taxRatePct ? ` (${input.totals.taxRatePct.toFixed(2)}%)` : "";
    drawTotalRow(`Tax: State${ratePart}`, fmtCurrency(input.totals.tax));
  }
  if (input.totals.paid > 0) {
    drawTotalRow("Funds Applied", `−${fmtCurrency(input.totals.paid)}`);
  }
  drawTotalRow("Total", fmtCurrency(input.totals.balance > 0 ? input.totals.balance : input.totals.total), {
    bold: true,
    size: 12,
    color: TEXT,
  });

  // ===== Notes =====
  if (input.invoice.notes) {
    ensure(40);
    y += 18;
    setFont(pdf, { bold: true, size: 9, color: TEXT });
    pdf.text("NOTES", MARGIN, y);
    y += 12;
    setFont(pdf, { size: 9, color: TEXT });
    const lines = wrap(pdf, input.invoice.notes, CONTENT_W);
    for (const l of lines) {
      ensure(12);
      pdf.text(l, MARGIN, y);
      y += 12;
    }
  }

  // Footer on every page
  drawPageFooter(pdf, input);
  const total = pdf.getNumberOfPages();
  for (let i = 1; i <= total; i++) {
    pdf.setPage(i);
    setFont(pdf, { size: 8, color: MUTED });
    const pageTxt = `Page ${i} of ${total}`;
    const w = pdf.getTextWidth(pageTxt);
    pdf.text(pageTxt, PAGE_W - MARGIN - w, PAGE_H - 22);
  }

  pdf.save(filename.endsWith(".pdf") ? filename : `${filename}.pdf`);
}

function drawPageFooter(pdf: jsPDF, input: InvoicePdfInput) {
  pdf.setDrawColor(...RULE);
  pdf.setLineWidth(0.5);
  pdf.line(MARGIN, PAGE_H - 36, PAGE_W - MARGIN, PAGE_H - 36);
  pdf.setFont("helvetica", "italic");
  pdf.setFontSize(8);
  pdf.setTextColor(...MUTED);
  const note = input.firm.footerNote || `Thank you for your business. Please remit payment to ${input.firm.name || "us"}.`;
  pdf.text(note, MARGIN, PAGE_H - 22);
}