import {
  newPDF,
  drawHeader,
  drawText,
  drawTable,
  moveDown,
  ensureSpace,
  COLORS,
  type PDFContext,
} from "./shared";
import { formatCurrency, formatDate, formatNumber } from "../utils";
import type { Customer, DeliveryNote, FuelPurchase, Supplier } from "../types";

export type ReportType =
  | "customer-delivery"
  | "vehicle-delivery"
  | "daily-summary"
  | "detailed-delivery"
  | "tank-delivery"
  | "purchase-summary"
  | "inventory";

export const REPORT_TYPES: { value: ReportType; label: string }[] = [
  { value: "customer-delivery", label: "Customer Delivery" },
  { value: "vehicle-delivery", label: "Vehicle Delivery" },
  { value: "daily-summary", label: "Daily Summary" },
  { value: "detailed-delivery", label: "Detailed Delivery" },
  { value: "tank-delivery", label: "Tank Delivery" },
  { value: "purchase-summary", label: "Purchase Summary" },
  { value: "inventory", label: "Inventory" },
];

export interface ReportContext {
  startDate: string;
  endDate: string;
  includePricing: boolean;
  notes: DeliveryNote[];
  purchases: FuelPurchase[];
  customers: Customer[];
  suppliers: Supplier[];
}

function finalize(ctx: PDFContext): Promise<Uint8Array> {
  const pages = ctx.doc.getPages();
  pages.forEach((p, i) => {
    const stamp = `Generated ${new Date().toLocaleString("en-ZA")} • Page ${i + 1} of ${pages.length}`;
    const w = ctx.font.widthOfTextAtSize(stamp, 8);
    p.drawText(stamp, { x: 555 - w, y: 30, size: 8, font: ctx.font, color: COLORS.muted });
  });
  return ctx.doc.save();
}

function groupBy<T, K extends string | number>(arr: T[], key: (t: T) => K): Map<K, T[]> {
  const out = new Map<K, T[]>();
  for (const t of arr) {
    const k = key(t);
    if (!out.has(k)) out.set(k, []);
    out.get(k)!.push(t);
  }
  return out;
}

export async function generateReport(type: ReportType, ctx: ReportContext): Promise<Uint8Array> {
  switch (type) {
    case "customer-delivery":
      return customerDelivery(ctx);
    case "vehicle-delivery":
      return vehicleDelivery(ctx);
    case "daily-summary":
      return dailySummary(ctx);
    case "detailed-delivery":
      return detailedDelivery(ctx);
    case "tank-delivery":
      return tankDelivery(ctx);
    case "purchase-summary":
      return purchaseSummary(ctx);
    case "inventory":
      return inventory(ctx);
  }
}

async function customerDelivery(ctx: ReportContext): Promise<Uint8Array> {
  const pdf = await newPDF();
  drawHeader(pdf, "Customer Delivery Report", `${formatDate(ctx.startDate)} to ${formatDate(ctx.endDate)}`);
  const customers = new Map(ctx.customers.map((c) => [c.id, c]));
  const grouped = groupBy(ctx.notes, (n) => n.customer);

  for (const [customerId, notes] of grouped) {
    // Pass the full "Customer Delivery Report (continued)" as the header
    // title — drawHeader will treat it as the title (no subtitle needed
    // since ensureSpace only forwards a single string).
    ensureSpace(pdf, 120, "Customer Delivery Report (continued)");
    const customer = customers.get(customerId);
    drawText(pdf, customer?.name || customerId, { size: 12, bold: true });
    moveDown(pdf, 14);
    const totalQty = notes.reduce((a, n) => a + n.qty_litres_supplied, 0);
    const totalValue = notes.reduce((a, n) => a + (n.total_value || 0), 0);
    const cols = [
      { header: "Date", width: 80, format: (v: string) => formatDate(v) },
      { header: "Note #", width: 90 },
      { header: "Vehicle", width: 110 },
      { header: "Qty (L)", width: 70, align: "right" as const, format: (v: number) => formatNumber(v) },
    ];
    if (ctx.includePricing) {
      cols.push(
        { header: "Total", width: 100, align: "right" as const, format: (v: number) => formatCurrency(v) },
      );
    }
    const rows = notes.map((n) => {
      const r: any[] = [n.date, n.number, n.vehicle_registration || "—", n.qty_litres_supplied];
      if (ctx.includePricing) r.push(n.total_value);
      return r;
    });
    drawTable(pdf, cols, rows);
    moveDown(pdf, 10);
    // Subtotal on a single line, right-aligned to the last column.
    // The qty and value are separated by a wide gap so the "L" (litres)
    // and "R" (Rand) don't visually run into each other.
    const subtotalRight = 40 + cols.reduce((a, c) => a + c.width, 0);
    if (ctx.includePricing) {
      const totalValStr = formatCurrency(totalValue);
      const valW = pdf.font.widthOfTextAtSize(totalValStr, 10);
      const subtotalStr = `Subtotal: ${formatNumber(totalQty)} L`;
      const subW = pdf.font.widthOfTextAtSize(subtotalStr, 10);
      drawText(pdf, subtotalStr, { x: subtotalRight - valW - 32 - subW, y: pdf.y, size: 10, bold: true });
      drawText(pdf, totalValStr, { x: subtotalRight - 8 - valW, y: pdf.y, size: 10, bold: true });
    } else {
      const subtotalStr = `Subtotal: ${formatNumber(totalQty)} L`;
      const subW = pdf.font.widthOfTextAtSize(subtotalStr, 10);
      const qtyColStart = 40 + cols.slice(0, 3).reduce((a, c) => a + c.width, 0);
      drawText(pdf, subtotalStr, { x: qtyColStart + cols[3].width - 8 - subW, y: pdf.y, size: 10, bold: true });
    }
    moveDown(pdf, 24);
  }
  return finalize(pdf);
}

async function vehicleDelivery(ctx: ReportContext): Promise<Uint8Array> {
  const pdf = await newPDF();
  drawHeader(pdf, "Vehicle Delivery Report", `${formatDate(ctx.startDate)} to ${formatDate(ctx.endDate)}`);
  const grouped = groupBy(ctx.notes, (n) => n.vehicle_registration || "(none)");
  for (const [vehicle, notes] of grouped) {
    ensureSpace(pdf, 120, "Vehicle Delivery Report (continued)");
    drawText(pdf, vehicle, { size: 12, bold: true });
    moveDown(pdf, 14);
    const cols = [
      { header: "Date", width: 80, format: (v: string) => formatDate(v) },
      { header: "Note #", width: 90 },
      { header: "Customer", width: 200 },
      { header: "Qty (L)", width: 70, align: "right" as const, format: (v: number) => formatNumber(v) },
    ];
    const customers = new Map(ctx.customers.map((c) => [c.id, c]));
    const rows = notes.map((n) => [n.date, n.number, customers.get(n.customer)?.name || n.customer, n.qty_litres_supplied]);
    drawTable(pdf, cols, rows);
    moveDown(pdf, 16);
  }
  return finalize(pdf);
}

async function dailySummary(ctx: ReportContext): Promise<Uint8Array> {
  const pdf = await newPDF();
  drawHeader(pdf, "Daily Summary", `${formatDate(ctx.startDate)} to ${formatDate(ctx.endDate)}`);
  const grouped = groupBy(ctx.notes, (n) => n.date);
  const cols = [
    { header: "Date", width: 120, format: (v: string) => formatDate(v) },
    { header: "Notes", width: 80, align: "right" as const },
    { header: "Total Qty (L)", width: 120, align: "right" as const, format: (v: number) => formatNumber(v) },
  ];
  if (ctx.includePricing) cols.push({ header: "Total Value", width: 120, align: "right" as const, format: (v: number) => formatCurrency(v) });
  const rows = Array.from(grouped.entries())
    .sort(([a], [b]) => a.localeCompare(b))
    .map(([date, notes]) => {
      const qty = notes.reduce((a, n) => a + n.qty_litres_supplied, 0);
      const val = notes.reduce((a, n) => a + (n.total_value || 0), 0);
      const r: any[] = [date, String(notes.length), qty];
      if (ctx.includePricing) r.push(val);
      return r;
    });
  drawTable(pdf, cols, rows);
  return finalize(pdf);
}

async function detailedDelivery(ctx: ReportContext): Promise<Uint8Array> {
  const pdf = await newPDF();
  drawHeader(pdf, "Detailed Delivery", `${formatDate(ctx.startDate)} to ${formatDate(ctx.endDate)}`);
  const customers = new Map(ctx.customers.map((c) => [c.id, c]));
  const cols = [
    { header: "Date", width: 70, format: (v: string) => formatDate(v) },
    { header: "Note #", width: 70 },
    { header: "Customer", width: 130 },
    { header: "Vehicle", width: 80 },
    { header: "Qty (L)", width: 60, align: "right" as const, format: (v: number) => formatNumber(v) },
  ];
  if (ctx.includePricing) {
    cols.push(
      { header: "Price/L", width: 60, align: "right" as const, format: (v: number) => formatCurrency(v) },
      { header: "Total", width: 80, align: "right" as const, format: (v: number) => formatCurrency(v) },
    );
  }
  const rows = ctx.notes.map((n) => {
    const r: any[] = [n.date, n.number, customers.get(n.customer)?.name || n.customer, n.vehicle_registration || "—", n.qty_litres_supplied];
    if (ctx.includePricing) r.push(n.price_per_litre, n.total_value);
    return r;
  });
  drawTable(pdf, cols, rows);
  return finalize(pdf);
}

async function tankDelivery(ctx: ReportContext): Promise<Uint8Array> {
  const pdf = await newPDF();
  drawHeader(pdf, "Tank Delivery Report", `${formatDate(ctx.startDate)} to ${formatDate(ctx.endDate)}`);
  const grouped = groupBy(ctx.notes, (n) => n.plant_dispensing || "(unspecified)");
  for (const [tank, notes] of grouped) {
    ensureSpace(pdf, 120, "Tank Delivery Report (continued)");
    drawText(pdf, tank, { size: 12, bold: true });
    moveDown(pdf, 14);
    const customers = new Map(ctx.customers.map((c) => [c.id, c]));
    const cols = [
      { header: "Date", width: 80, format: (v: string) => formatDate(v) },
      { header: "Note #", width: 80 },
      { header: "Customer", width: 180 },
      { header: "Vehicle", width: 80 },
      { header: "Qty (L)", width: 80, align: "right" as const, format: (v: number) => formatNumber(v) },
    ];
    const rows = notes.map((n) => [n.date, n.number, customers.get(n.customer)?.name || n.customer, n.vehicle_registration || "—", n.qty_litres_supplied]);
    drawTable(pdf, cols, rows);
    moveDown(pdf, 16);
  }
  return finalize(pdf);
}

async function purchaseSummary(ctx: ReportContext): Promise<Uint8Array> {
  const pdf = await newPDF();
  drawHeader(pdf, "Purchase Summary", `${formatDate(ctx.startDate)} to ${formatDate(ctx.endDate)}`);
  const suppliers = new Map(ctx.suppliers.map((s) => [s.id, s]));
  const cols = [
    { header: "Month", width: 100 },
    { header: "Supplier", width: 160 },
    { header: "Records", width: 60, align: "right" as const },
    { header: "Total Qty (L)", width: 100, align: "right" as const, format: (v: number) => formatNumber(v) },
    { header: "Total Cost", width: 120, align: "right" as const, format: (v: number) => formatCurrency(v) },
  ];
  const grouped = groupBy(ctx.purchases, (p) => p.purchase_date.slice(0, 7));
  const rows: any[][] = [];
  for (const [month, purchases] of grouped) {
    let monthTotal = 0;
    let monthQty = 0;
    for (const p of purchases) {
      const sup = suppliers.get(p.supplier);
      rows.push([month, sup?.name || p.supplier, "1", p.purchase_qty, p.purchase_qty * p.purchase_price]);
      monthTotal += p.purchase_qty * p.purchase_price;
      monthQty += p.purchase_qty;
    }
    rows.push([`${month} total`, "", String(purchases.length), monthQty, monthTotal]);
  }
  drawTable(pdf, cols, rows);
  return finalize(pdf);
}

async function inventory(ctx: ReportContext): Promise<Uint8Array> {
  const pdf = await newPDF();
  drawHeader(pdf, "Inventory Balance", `${formatDate(ctx.startDate)} to ${formatDate(ctx.endDate)}`);

  const totalPurchased = ctx.purchases.reduce((a, p) => a + p.purchase_qty, 0);
  const purchaseValue = ctx.purchases.reduce((a, p) => a + p.purchase_qty * p.purchase_price, 0);
  const totalDelivered = ctx.notes.reduce((a, n) => a + n.qty_litres_supplied, 0);
  const deliveryValue = ctx.notes.reduce((a, n) => a + (n.total_value || 0), 0);
  const balance = totalPurchased - totalDelivered;
  const margin = deliveryValue - (totalDelivered * (totalPurchased > 0 ? purchaseValue / totalPurchased : 0));

  const cols = [
    { header: "Metric", width: 220 },
    { header: "Value", width: 200, align: "right" as const },
  ];
  const rows: any[][] = [
    ["Total fuel purchased", `${formatNumber(totalPurchased)} L`],
    ["Total purchase cost", formatCurrency(purchaseValue)],
    ["Total fuel delivered", `${formatNumber(totalDelivered)} L`],
    ["Total delivery value", formatCurrency(deliveryValue)],
    ["Inventory balance (L)", `${formatNumber(balance)} L`],
    ["Estimated margin", formatCurrency(margin)],
  ];
  drawTable(pdf, cols, rows);
  return finalize(pdf);
}