/**
 * Config-driven invoice PDF renderer used by the desktop and web apps.
 *
 * This is distinct from `generateInvoicePDF` in `./pdf` which uses a
 * template registry (mandala / minimal) and is for the CLI standalone
 * invoice workflow. The app renderer here takes an `InvoiceTemplateConfig`
 * (the user-editable config stored in the invoice_templates DB table)
 * and renders directly.
 */

import {
  type Color,
  type FontInput,
  measureText,
  PDF,
  type PDFImage,
  type PDFPage,
  rgb,
  StandardFonts,
} from "@libpdf/core";
import { DEFAULT_TEMPLATES, type InvoiceTemplateConfig } from "../db";

// ── Types ──────────────────────────────────────────────────

export interface InvoicePDFLineItem {
  description: string;
  quantity: number;
  rate: number;
  amount: number;
  projectName?: string | null;
}

export interface InvoicePDFInvoiceData {
  invoiceNumber: string;
  issueDate: Date;
  dueDate?: Date | null;
  periodStart?: Date | null;
  periodEnd?: Date | null;
  clientName?: string | null;
  clientEmail?: string | null;
  clientAddress?: string | null;
  subtotal: number;
  taxRate: number;
  taxAmount: number;
  total: number;
  currency: string;
  notes?: string | null;
  paymentNotes?: string | null;
  lineItems: InvoicePDFLineItem[];
}

export interface RenderInvoicePDFProps {
  invoice: InvoicePDFInvoiceData;
  template?: InvoiceTemplateConfig;
}

// ── Helpers ────────────────────────────────────────────────

function formatCurrency(cents: number, currency = "USD"): string {
  return new Intl.NumberFormat("en-US", {
    style: "currency",
    currency,
    minimumFractionDigits: 2,
  }).format(cents / 100);
}

function formatDate(date: Date): string {
  return new Intl.DateTimeFormat("en-US", {
    month: "short",
    day: "numeric",
    year: "numeric",
  }).format(date);
}

function hexToRgb(hex: string) {
  const h = hex.replace("#", "");
  const r = Number.parseInt(h.substring(0, 2), 16) / 255;
  const g = Number.parseInt(h.substring(2, 4), 16) / 255;
  const b = Number.parseInt(h.substring(4, 6), 16) / 255;
  return rgb(r, g, b);
}

// ── Image helpers ─────────────────────────────────────────

function dataUriToBytes(dataUri: string): Uint8Array {
  const base64 = dataUri.split(",")[1];
  if (!base64) throw new Error("Invalid data URI: missing base64 payload");
  return Uint8Array.from(atob(base64), (c) => c.charCodeAt(0));
}

/**
 * Decode a logo source into raw bytes. Only `data:` URIs are accepted —
 * fetching arbitrary `http(s)://` URLs from the renderer would be an
 * SSRF gadget, since this function runs server-side from API routes
 * that accept user-supplied template configs. If hosted-URL logos are
 * needed in the future, add a strict allowlist of trusted asset hosts.
 */
async function loadImageBytes(src: string): Promise<Uint8Array> {
  if (!src.startsWith("data:")) {
    throw new Error(
      "Invoice logo must be a data URI; remote URL logos are not supported",
    );
  }
  return dataUriToBytes(src);
}

// ── Constants ──────────────────────────────────────────────

const PAGE_WIDTH = 595.28;
const PAGE_HEIGHT = 841.89;
const PADDING = 50;
const CONTENT_WIDTH = PAGE_WIDTH - PADDING * 2;
const TOP_Y = PAGE_HEIGHT - PADDING;
const BOTTOM_MARGIN = 50;
const RIGHT_EDGE = PAGE_WIDTH - PADDING;

const LOGO_MAX_HEIGHT = 60;
const LOGO_MAX_WIDTH = 150;

// Table column right-edges for alignment
const COL_HOURS_RIGHT = 400;
const COL_RATE_RIGHT = 470;
const COL_AMOUNT_RIGHT = RIGHT_EDGE - 10;

// ── Text helpers ───────────────────────────────────────────

const FONT = StandardFonts.Helvetica;
const FONT_BOLD = StandardFonts.HelveticaBold;

function tw(text: string, font: FontInput, size: number): number {
  return measureText(text, font, size);
}

function drawRight(
  page: PDFPage,
  text: string,
  rightX: number,
  y: number,
  size: number,
  font: FontInput,
  color: Color,
) {
  const w = tw(text, font, size);
  page.drawText(text, { x: rightX - w, y, size, font, color });
}

// ── PDF Generation ─────────────────────────────────────────

/**
 * Render an invoice PDF using a user-configurable template.
 *
 * This function is shared between the desktop and web apps. It takes an
 * `InvoiceTemplateConfig` from the DB and produces a `Uint8Array` that
 * can be streamed as a PDF response or attached to an email.
 */
export async function renderInvoicePDF({
  invoice,
  template = DEFAULT_TEMPLATES.classic,
}: RenderInvoicePDFProps): Promise<Uint8Array> {
  const pdf = PDF.create();

  const primaryColor = hexToRgb(template.primaryColor);
  const accentColor = hexToRgb(template.accentColor);
  const textColor = hexToRgb(template.textColor);
  const lightGray = rgb(0.94, 0.94, 0.94);
  const medGray = rgb(0.88, 0.88, 0.88);
  const darkGray = rgb(0.4, 0.4, 0.4);

  // ── Page management ────────────────────────────────────

  let page = pdf.addPage({ size: "a4" });
  let y = TOP_Y;

  /** Add a new page and reset y to the top content area. */
  function newPage(): void {
    page = pdf.addPage({ size: "a4" });
    y = TOP_Y;
  }

  /** If the remaining space is less than `needed`, start a new page. */
  function ensureSpace(needed: number): void {
    if (y - needed < BOTTOM_MARGIN) newPage();
  }

  // ── Logo embedding ─────────────────────────────────────

  let logo: PDFImage | null = null;
  if (template.showLogo && template.logo) {
    try {
      const bytes = await loadImageBytes(template.logo);
      logo = pdf.embedImage(bytes);
    } catch {
      // Failed to load logo — fall through to larger company name
    }
  }

  // ── Header ─────────────────────────────────────────────

  if (template.headerStyle === "modern") {
    y -= 10;

    // Logo centered above title
    if (logo) {
      const scale = Math.min(
        LOGO_MAX_WIDTH / logo.width,
        LOGO_MAX_HEIGHT / logo.height,
        1,
      );
      const drawW = logo.width * scale;
      const drawH = logo.height * scale;
      page.drawImage(logo, {
        x: (PAGE_WIDTH - drawW) / 2,
        y: y - drawH,
        width: drawW,
        height: drawH,
      });
      y -= drawH + 10;
    }

    const titleW = tw("INVOICE", FONT_BOLD, 32);
    page.drawText("INVOICE", {
      x: (PAGE_WIDTH - titleW) / 2,
      y,
      size: 32,
      font: FONT_BOLD,
      color: primaryColor,
    });
    y -= 20;

    const numW = tw(invoice.invoiceNumber, FONT, 14);
    page.drawText(invoice.invoiceNumber, {
      x: (PAGE_WIDTH - numW) / 2,
      y,
      size: 14,
      font: FONT,
      color: darkGray,
    });
    y -= 20;

    if (template.showCompanyDetails) {
      // If no logo loaded, render company name larger as visual anchor
      const nameSize = logo ? 14 : 18;
      const compW = tw(template.companyName, FONT_BOLD, nameSize);
      page.drawText(template.companyName, {
        x: (PAGE_WIDTH - compW) / 2,
        y,
        size: nameSize,
        font: FONT_BOLD,
        color: textColor,
      });
      y -= nameSize;
      if (template.companyEmail) {
        const ew = tw(template.companyEmail, FONT, 9);
        page.drawText(template.companyEmail, {
          x: (PAGE_WIDTH - ew) / 2,
          y,
          size: 9,
          font: FONT,
          color: darkGray,
        });
        y -= 12;
      }
      if (template.companyPhone) {
        const pw = tw(template.companyPhone, FONT, 9);
        page.drawText(template.companyPhone, {
          x: (PAGE_WIDTH - pw) / 2,
          y,
          size: 9,
          font: FONT,
          color: darkGray,
        });
        y -= 12;
      }
    }
    y -= 30;
  } else if (template.headerStyle === "minimal") {
    // Logo left-aligned before title
    if (logo) {
      const scale = Math.min(
        LOGO_MAX_WIDTH / logo.width,
        LOGO_MAX_HEIGHT / logo.height,
        1,
      );
      const drawW = logo.width * scale;
      const drawH = logo.height * scale;
      page.drawImage(logo, {
        x: PADDING,
        y: y - drawH,
        width: drawW,
        height: drawH,
      });
      y -= drawH + 10;
    }

    const titleText = `Invoice ${invoice.invoiceNumber}`;
    page.drawText(titleText, {
      x: PADDING,
      y,
      size: 16,
      font: FONT_BOLD,
      color: primaryColor,
    });
    y -= 15;
    page.drawLine({
      start: { x: PADDING, y },
      end: { x: RIGHT_EDGE, y },
      thickness: 1,
      color: medGray,
    });
    y -= 20;
  } else {
    // Classic: title left, company right

    // Logo top-right when company details shown, else top-left
    if (logo) {
      const scale = Math.min(
        LOGO_MAX_WIDTH / logo.width,
        LOGO_MAX_HEIGHT / logo.height,
        1,
      );
      const drawW = logo.width * scale;
      const drawH = logo.height * scale;
      if (template.showCompanyDetails) {
        page.drawImage(logo, {
          x: RIGHT_EDGE - drawW,
          y: y - drawH,
          width: drawW,
          height: drawH,
        });
      } else {
        page.drawImage(logo, {
          x: PADDING,
          y: y - drawH,
          width: drawW,
          height: drawH,
        });
      }
    }

    page.drawText("INVOICE", {
      x: PADDING,
      y,
      size: 24,
      font: FONT_BOLD,
      color: primaryColor,
    });
    y -= 16;
    page.drawText(invoice.invoiceNumber, {
      x: PADDING,
      y,
      size: 12,
      font: FONT,
      color: darkGray,
    });

    if (template.showCompanyDetails) {
      // Company details below logo (if logo present) or at top-right
      let compY = logo
        ? TOP_Y - Math.min(LOGO_MAX_HEIGHT, logo.height) - 10
        : TOP_Y;
      // If no logo loaded, render company name larger as visual anchor
      const nameSize = logo ? 14 : 18;
      drawRight(
        page,
        template.companyName,
        RIGHT_EDGE,
        compY,
        nameSize,
        FONT_BOLD,
        textColor,
      );
      compY -= nameSize;
      if (template.companyEmail) {
        drawRight(
          page,
          template.companyEmail,
          RIGHT_EDGE,
          compY,
          9,
          FONT,
          darkGray,
        );
        compY -= 12;
      }
      if (template.companyAddress) {
        drawRight(
          page,
          template.companyAddress,
          RIGHT_EDGE,
          compY,
          9,
          FONT,
          darkGray,
        );
        compY -= 12;
      }
      if (template.companyPhone) {
        drawRight(
          page,
          template.companyPhone,
          RIGHT_EDGE,
          compY,
          9,
          FONT,
          darkGray,
        );
      }
    }
    y -= 30;
  }

  // ── Bill To ────────────────────────────────────────────

  ensureSpace(60);

  page.drawText("BILL TO", {
    x: PADDING,
    y,
    size: 8,
    font: FONT_BOLD,
    color: darkGray,
  });
  y -= 14;

  if (invoice.clientName) {
    page.drawText(invoice.clientName, {
      x: PADDING,
      y,
      size: 12,
      font: FONT_BOLD,
      color: textColor,
    });
    y -= 14;
    if (invoice.clientEmail) {
      page.drawText(invoice.clientEmail, {
        x: PADDING,
        y,
        size: 10,
        font: FONT,
        color: darkGray,
      });
      y -= 12;
    }
    if (invoice.clientAddress) {
      page.drawText(invoice.clientAddress, {
        x: PADDING,
        y,
        size: 10,
        font: FONT,
        color: darkGray,
      });
      y -= 12;
    }
  } else {
    page.drawText("No client specified", {
      x: PADDING,
      y,
      size: 10,
      font: FONT,
      color: darkGray,
    });
    y -= 12;
  }
  y -= 20;

  // ── Dates ──────────────────────────────────────────────

  ensureSpace(50);

  page.drawText("Issue Date", {
    x: PADDING,
    y,
    size: 8,
    font: FONT,
    color: darkGray,
  });
  y -= 12;
  page.drawText(formatDate(new Date(invoice.issueDate)), {
    x: PADDING,
    y,
    size: 10,
    font: FONT,
    color: textColor,
  });

  if (invoice.dueDate) {
    const midX = PAGE_WIDTH / 2;
    page.drawText("Due Date", {
      x: midX,
      y: y + 12,
      size: 8,
      font: FONT,
      color: darkGray,
    });
    page.drawText(formatDate(new Date(invoice.dueDate)), {
      x: midX,
      y,
      size: 10,
      font: FONT,
      color: textColor,
    });
  }
  y -= 20;

  if (invoice.periodStart && invoice.periodEnd) {
    page.drawText("Period", {
      x: PADDING,
      y,
      size: 8,
      font: FONT,
      color: darkGray,
    });
    y -= 12;
    page.drawText(
      `${formatDate(new Date(invoice.periodStart))} - ${formatDate(new Date(invoice.periodEnd))}`,
      { x: PADDING, y, size: 10, font: FONT, color: textColor },
    );
    y -= 20;
  }
  y -= 10;

  // ── Line Items Table ───────────────────────────────────

  const rowH = 25;

  /** Draw the table header row on the current page at the current y. */
  function drawTableHeader(): void {
    page.drawRectangle({
      x: PADDING,
      y: y - rowH,
      width: CONTENT_WIDTH,
      height: rowH,
      color: rgb(0.96, 0.96, 0.96),
    });
    page.drawLine({
      start: { x: PADDING, y: y - rowH },
      end: { x: RIGHT_EDGE, y: y - rowH },
      thickness: 1,
      color: medGray,
    });

    const hY = y - rowH + 8;
    page.drawText("DESCRIPTION", {
      x: PADDING + 10,
      y: hY,
      size: 8,
      font: FONT_BOLD,
      color: darkGray,
    });
    if (template.showHours)
      drawRight(page, "HOURS", COL_HOURS_RIGHT, hY, 8, FONT_BOLD, darkGray);
    if (template.showRate)
      drawRight(page, "RATE", COL_RATE_RIGHT, hY, 8, FONT_BOLD, darkGray);
    drawRight(page, "AMOUNT", COL_AMOUNT_RIGHT, hY, 8, FONT_BOLD, darkGray);
    y -= rowH;
  }

  // Initial table header
  ensureSpace(rowH * 2); // header + at least one data row
  drawTableHeader();

  // Data rows
  for (const item of invoice.lineItems) {
    // Check if we need a new page before drawing this row
    if (y - rowH < BOTTOM_MARGIN) {
      newPage();
      drawTableHeader();
    }

    const cellY = y - rowH + 8;
    page.drawLine({
      start: { x: PADDING, y: y - rowH },
      end: { x: RIGHT_EDGE, y: y - rowH },
      thickness: 0.5,
      color: lightGray,
    });

    const desc = item.description.replace(/ - [\d.]+ hours$/, "");
    page.drawText(desc, {
      x: PADDING + 10,
      y: cellY,
      size: 10,
      font: FONT,
      color: textColor,
    });

    if (template.showHours) {
      drawRight(
        page,
        (item.quantity / 60).toFixed(1),
        COL_HOURS_RIGHT,
        cellY,
        10,
        FONT,
        textColor,
      );
    }
    if (template.showRate) {
      drawRight(
        page,
        formatCurrency(item.rate, invoice.currency),
        COL_RATE_RIGHT,
        cellY,
        10,
        FONT,
        textColor,
      );
    }
    drawRight(
      page,
      formatCurrency(item.amount, invoice.currency),
      COL_AMOUNT_RIGHT,
      cellY,
      10,
      FONT,
      textColor,
    );
    y -= rowH;
  }
  y -= 20;

  // ── Totals ─────────────────────────────────────────────

  ensureSpace(80);

  const totalsX = RIGHT_EDGE - 200;

  page.drawText("Subtotal", {
    x: totalsX,
    y,
    size: 10,
    font: FONT,
    color: textColor,
  });
  drawRight(
    page,
    formatCurrency(invoice.subtotal, invoice.currency),
    RIGHT_EDGE,
    y,
    10,
    FONT,
    textColor,
  );
  y -= 16;

  if (invoice.taxRate > 0) {
    page.drawText(`Tax (${(invoice.taxRate / 100).toFixed(1)}%)`, {
      x: totalsX,
      y,
      size: 10,
      font: FONT,
      color: textColor,
    });
    drawRight(
      page,
      formatCurrency(invoice.taxAmount, invoice.currency),
      RIGHT_EDGE,
      y,
      10,
      FONT,
      textColor,
    );
    y -= 16;
  }

  y -= 4;
  page.drawLine({
    start: { x: totalsX, y },
    end: { x: RIGHT_EDGE, y },
    thickness: 2,
    color: primaryColor,
  });
  y -= 14;

  page.drawText("Total", {
    x: totalsX,
    y,
    size: 12,
    font: FONT_BOLD,
    color: textColor,
  });
  drawRight(
    page,
    formatCurrency(invoice.total, invoice.currency),
    RIGHT_EDGE,
    y,
    12,
    FONT_BOLD,
    primaryColor,
  );
  y -= 30;

  // ── Footer ─────────────────────────────────────────────

  const hasPaymentMethods =
    !!template.paymentMethods && template.paymentMethods.length > 0;
  const hasFooter =
    invoice.notes ||
    invoice.paymentNotes ||
    template.footerText ||
    template.paymentInstructions ||
    hasPaymentMethods;
  if (hasFooter) {
    ensureSpace(60);

    y -= 10;
    page.drawLine({
      start: { x: PADDING, y },
      end: { x: RIGHT_EDGE, y },
      thickness: 0.5,
      color: medGray,
    });
    y -= 20;

    if (invoice.notes) {
      ensureSpace(40);
      page.drawText("Notes", {
        x: PADDING,
        y,
        size: 9,
        font: FONT_BOLD,
        color: darkGray,
      });
      y -= 12;
      page.drawText(invoice.notes, {
        x: PADDING,
        y,
        size: 9,
        font: FONT,
        color: darkGray,
      });
      y -= 20;
    }

    const paymentText = invoice.paymentNotes || template.paymentInstructions;
    if (paymentText) {
      ensureSpace(40);
      page.drawText("Payment Instructions", {
        x: PADDING,
        y,
        size: 9,
        font: FONT_BOLD,
        color: darkGray,
      });
      y -= 12;
      page.drawText(paymentText, {
        x: PADDING,
        y,
        size: 9,
        font: FONT,
        color: darkGray,
      });
      y -= 20;
    }

    // Structured payment methods (matches the CLI mandala/minimal
    // templates, which already render these). Free-text paymentNotes /
    // paymentInstructions above remain for back-compat; both can appear.
    if (template.paymentMethods) {
      for (const method of template.paymentMethods) {
        ensureSpace(24);
        page.drawText(method.label, {
          x: PADDING,
          y,
          size: 9,
          font: FONT_BOLD,
          color: darkGray,
        });
        y -= 12;
        for (const [key, value] of Object.entries(method.details)) {
          ensureSpace(12);
          page.drawText(`${key}: ${value}`, {
            x: PADDING + 8,
            y,
            size: 8,
            font: FONT,
            color: darkGray,
          });
          y -= 11;
        }
        y -= 8;
      }
    }

    if (template.footerText) {
      ensureSpace(20);
      const fw = tw(template.footerText, FONT, 10);
      page.drawText(template.footerText, {
        x: (PAGE_WIDTH - fw) / 2,
        y,
        size: 10,
        font: FONT,
        color: accentColor,
      });
    }
  }

  return pdf.save();
}