import { PDF, rgb, StandardFonts } from "@libpdf/core";
import type { InvoicePDFData, InvoiceTemplate } from "../types";
import {
  fonts,
  formatCurrency,
  formatDate,
  padInvoiceNumber,
  rightAlignX,
} from "./types";

const colors = {
  black: rgb(0.12, 0.12, 0.12),
  gray: rgb(0.45, 0.45, 0.45),
  lightGray: rgb(0.88, 0.88, 0.88),
  accent: rgb(0.25, 0.35, 0.45),
  white: rgb(1, 1, 1),
};

const PAGE_WIDTH = 612;
const PAGE_HEIGHT = 792;
const MARGIN = 50;
const RIGHT_EDGE = PAGE_WIDTH - MARGIN;
const CONTENT_WIDTH = RIGHT_EDGE - MARGIN;

/** Minimum Y before we'd clip into the footer area */
const FOOTER_GUARD = 100;

function drawSeparator(
  page: ReturnType<ReturnType<typeof PDF.create>["addPage"]>,
  y: number,
  x = MARGIN,
  width = CONTENT_WIDTH,
): void {
  page.drawLine({
    start: { x, y },
    end: { x: x + width, y },
    color: colors.lightGray,
    thickness: 0.5,
  });
}

export const minimalTemplate: InvoiceTemplate = {
  name: "minimal",
  description: "Clean, professional invoice on white background",

  async render(data: InvoicePDFData): Promise<Uint8Array> {
    const pdf = PDF.create();
    const page = pdf.addPage({ width: PAGE_WIDTH, height: PAGE_HEIGHT });
    let y = PAGE_HEIGHT - MARGIN;

    // ── Header: Company name top-left, INVOICE label top-right ──

    page.drawText(data.from.companyName, {
      x: MARGIN,
      y,
      size: 16,
      color: colors.black,
      font: StandardFonts.HelveticaBold,
    });

    const invoiceLabel = "INVOICE";
    page.drawText(invoiceLabel, {
      x: rightAlignX(invoiceLabel, RIGHT_EDGE, 16, fonts.helveticaBold),
      y,
      size: 16,
      color: colors.accent,
      font: StandardFonts.HelveticaBold,
    });

    // ── From address block (left side) ──

    y -= 20;
    const fromStartY = y;

    if (data.from.address) {
      for (const line of data.from.address.split("\n")) {
        const trimmed = line.trim();
        if (!trimmed) continue;
        page.drawText(trimmed, {
          x: MARGIN,
          y,
          size: 9,
          color: colors.gray,
          font: StandardFonts.Helvetica,
        });
        y -= 13;
      }
    }
    if (data.from.email) {
      page.drawText(data.from.email, {
        x: MARGIN,
        y,
        size: 9,
        color: colors.gray,
        font: StandardFonts.Helvetica,
      });
      y -= 13;
    }
    if (data.from.phone) {
      page.drawText(data.from.phone, {
        x: MARGIN,
        y,
        size: 9,
        color: colors.gray,
        font: StandardFonts.Helvetica,
      });
      y -= 13;
    }

    // ── Invoice meta: number, date, due date, period — right-aligned ──

    let metaY = fromStartY;
    const metaLabelX = RIGHT_EDGE - 160;

    const metaFields: [string, string][] = [
      ["Invoice #", padInvoiceNumber(data.invoiceNumber)],
      ["Date", formatDate(data.invoiceDate)],
    ];
    if (data.dueDate) {
      metaFields.push(["Due Date", formatDate(data.dueDate)]);
    }
    if (data.periodStart && data.periodEnd) {
      metaFields.push([
        "Period",
        `${formatDate(data.periodStart)} - ${formatDate(data.periodEnd)}`,
      ]);
    }

    for (const [label, value] of metaFields) {
      page.drawText(label, {
        x: metaLabelX,
        y: metaY,
        size: 9,
        color: colors.gray,
        font: StandardFonts.Helvetica,
      });
      page.drawText(value, {
        x: rightAlignX(value, RIGHT_EDGE, 9, fonts.courier),
        y: metaY,
        size: 9,
        color: colors.black,
        font: StandardFonts.Courier,
      });
      metaY -= 14;
    }

    // Use whichever side went lower
    y = Math.min(y, metaY) - 16;

    // ── Bill To section ──

    page.drawText("BILL TO", {
      x: MARGIN,
      y,
      size: 8,
      color: colors.accent,
      font: StandardFonts.HelveticaBold,
    });
    y -= 16;

    page.drawText(data.to.name, {
      x: MARGIN,
      y,
      size: 11,
      color: colors.black,
      font: StandardFonts.HelveticaBold,
    });
    y -= 15;

    if (data.to.email) {
      page.drawText(data.to.email, {
        x: MARGIN,
        y,
        size: 9,
        color: colors.gray,
        font: StandardFonts.Helvetica,
      });
      y -= 13;
    }

    if (data.to.address) {
      for (const line of data.to.address.split("\n")) {
        const trimmed = line.trim();
        if (!trimmed) continue;
        page.drawText(trimmed, {
          x: MARGIN,
          y,
          size: 9,
          color: colors.gray,
          font: StandardFonts.Helvetica,
        });
        y -= 13;
      }
    }

    // ── Separator before line items ──

    y -= 12;
    drawSeparator(page, y);
    y -= 20;

    // ── Line items table header ──

    const colQtyX = RIGHT_EDGE - 220;
    const colRateX = RIGHT_EDGE - 140;
    const colAmountX = RIGHT_EDGE;

    page.drawText("Description", {
      x: MARGIN,
      y,
      size: 8,
      color: colors.accent,
      font: StandardFonts.HelveticaBold,
    });
    page.drawText("Qty", {
      x: colQtyX,
      y,
      size: 8,
      color: colors.accent,
      font: StandardFonts.HelveticaBold,
    });
    page.drawText("Rate", {
      x: colRateX,
      y,
      size: 8,
      color: colors.accent,
      font: StandardFonts.HelveticaBold,
    });

    const amountHeader = "Amount";
    page.drawText(amountHeader, {
      x: rightAlignX(amountHeader, colAmountX, 8, fonts.helveticaBold),
      y,
      size: 8,
      color: colors.accent,
      font: StandardFonts.HelveticaBold,
    });

    y -= 10;
    drawSeparator(page, y);
    y -= 16;

    // ── Line items ──

    for (const item of data.lineItems) {
      if (y < FOOTER_GUARD) break; // safety guard

      // Description (with optional project name)
      const desc = item.projectName
        ? `${item.description} (${item.projectName})`
        : item.description;

      page.drawText(desc, {
        x: MARGIN,
        y,
        size: 9,
        color: colors.black,
        font: StandardFonts.Helvetica,
        maxWidth: colQtyX - MARGIN - 10,
      });

      const qtyStr = `${item.quantity} ${item.quantityType}`;
      page.drawText(qtyStr, {
        x: colQtyX,
        y,
        size: 9,
        color: colors.black,
        font: StandardFonts.Courier,
      });

      const rateStr = formatCurrency(item.rate, data.currency);
      page.drawText(rateStr, {
        x: colRateX,
        y,
        size: 9,
        color: colors.black,
        font: StandardFonts.Courier,
      });

      const amtStr = formatCurrency(item.amount, data.currency);
      page.drawText(amtStr, {
        x: rightAlignX(amtStr, colAmountX, 9, fonts.courier),
        y,
        size: 9,
        color: colors.black,
        font: StandardFonts.Courier,
      });

      y -= 20;
    }

    // ── Credits (negative line items) ──

    for (const credit of data.credits) {
      if (y < FOOTER_GUARD) break;

      page.drawText(credit.description, {
        x: MARGIN,
        y,
        size: 9,
        color: colors.gray,
        font: StandardFonts.HelveticaOblique,
      });

      const creditStr = `-${formatCurrency(credit.amount, data.currency)}`;
      page.drawText(creditStr, {
        x: rightAlignX(creditStr, colAmountX, 9, fonts.courier),
        y,
        size: 9,
        color: colors.accent,
        font: StandardFonts.Courier,
      });

      y -= 20;
    }

    // ── Totals section ──

    y -= 6;
    drawSeparator(page, y, RIGHT_EDGE - 220, 220);
    y -= 18;

    // Subtotal
    const subtotalLabel = "Subtotal";
    const subtotalStr = formatCurrency(data.subtotal, data.currency);
    page.drawText(subtotalLabel, {
      x: RIGHT_EDGE - 220,
      y,
      size: 9,
      color: colors.gray,
      font: StandardFonts.Helvetica,
    });
    page.drawText(subtotalStr, {
      x: rightAlignX(subtotalStr, colAmountX, 9, fonts.courier),
      y,
      size: 9,
      color: colors.black,
      font: StandardFonts.Courier,
    });
    y -= 16;

    // Tax (if applicable)
    if (data.taxRate > 0) {
      const taxLabel = `Tax (${(data.taxRate / 100).toFixed(1)}%)`;
      const taxStr = formatCurrency(data.taxAmount, data.currency);
      page.drawText(taxLabel, {
        x: RIGHT_EDGE - 220,
        y,
        size: 9,
        color: colors.gray,
        font: StandardFonts.Helvetica,
      });
      page.drawText(taxStr, {
        x: rightAlignX(taxStr, colAmountX, 9, fonts.courier),
        y,
        size: 9,
        color: colors.black,
        font: StandardFonts.Courier,
      });
      y -= 16;
    }

    // Total
    drawSeparator(page, y, RIGHT_EDGE - 220, 220);
    y -= 18;

    const totalLabel = `Total ${data.currency}`;
    const totalStr = formatCurrency(data.total, data.currency);
    page.drawText(totalLabel, {
      x: RIGHT_EDGE - 220,
      y,
      size: 12,
      color: colors.black,
      font: StandardFonts.HelveticaBold,
    });
    page.drawText(totalStr, {
      x: rightAlignX(totalStr, colAmountX, 12, fonts.courierBold),
      y,
      size: 12,
      color: colors.black,
      font: StandardFonts.CourierBold,
    });

    // ── Payment methods (bottom section) ──

    if (data.paymentMethods && data.paymentMethods.length > 0) {
      // Position payment info well below totals, or at a fixed position if
      // totals ended high up
      y = Math.min(y - 40, 200);

      page.drawText("PAYMENT", {
        x: MARGIN,
        y,
        size: 8,
        color: colors.accent,
        font: StandardFonts.HelveticaBold,
      });
      y -= 16;

      for (const method of data.paymentMethods) {
        page.drawText(method.label, {
          x: MARGIN,
          y,
          size: 9,
          color: colors.black,
          font: StandardFonts.HelveticaBold,
        });
        y -= 13;

        for (const [key, value] of Object.entries(method.details)) {
          page.drawText(`${key}: ${value}`, {
            x: MARGIN,
            y,
            size: 8,
            color: colors.gray,
            font: StandardFonts.Courier,
          });
          y -= 12;
        }
        y -= 6;
      }
    }

    // ── Payment notes ──

    if (data.paymentNotes) {
      y = Math.min(y - 10, 80);
      page.drawText(data.paymentNotes, {
        x: MARGIN,
        y,
        size: 8,
        color: colors.gray,
        font: StandardFonts.Helvetica,
        maxWidth: CONTENT_WIDTH,
      });
    }

    // ── Notes (bottom of page) ──

    if (data.notes) {
      page.drawText(data.notes, {
        x: MARGIN,
        y: MARGIN,
        size: 7,
        color: colors.gray,
        font: StandardFonts.HelveticaOblique,
        maxWidth: CONTENT_WIDTH,
      });
    }

    return pdf.save();
  },
};