import * as XLSX from "xlsx";
import type { ProductRecord } from "./types.ts";

const ASIN_REGEX = /^B[0-9A-Z]{9}$/;

const COLUMN_CANDIDATES = {
  asin: ["asin"],
  name: ["name", "product name", "title", "product title"],
  cost: ["unit cost", "cost", "unitcost", "unit_cost", "price", "buy cost"],
  brand: ["brand"],
  category: ["category"],
  amazonRank: ["amazon rank", "amazonrank", "sales rank", "bsr"],
  avgPrice90: [
    "90 day average",
    "90-day average",
    "avg price 90d",
    "avg 90 day",
    "90d average",
  ],
  sellingPrice: ["selling price", "sale price", "sell price"],
  fbaNet: ["fba net", "fbanet", "fba_net"],
  grossProfit: ["gross profit $", "gross profit", "grossprofit"],
  grossProfitPct: ["gross profit %", "gross profit pct", "grossprofitpct"],
  netProfit: ["net profit", "netprofit"],
  roi: ["roi", "return on investment"],
  moq: ["moq", "min order qty", "minimum order quantity"],
  moqCost: ["moq cost", "moqcost", "moq_cost"],
  totalQty: ["total qty avail", "totalqtyavail", "qty available", "quantity"],
  link: ["link", "url", "source"],
  asinLink: ["asin link", "amazon link", "asin url"],
  sourceUrl: ["source url", "supplier url", "source link"],
  supplier: ["supplier", "vendor"],
  promoCouponCode: [
    "promo/coupon code",
    "promo coupon code",
    "coupon code",
    "promo code",
  ],
  notes: ["notes", "note"],
  leadDate: ["date", "lead date"],
} as const;

type ColumnKey = keyof typeof COLUMN_CANDIDATES;
type ColumnMap = Record<ColumnKey, string | undefined>;

export function readProducts(filePath: string): ProductRecord[] {
  const workbook = XLSX.readFile(filePath);
  const sheetName = workbook.SheetNames[0];
  if (!sheetName) throw new Error("No sheets found in file");

  const sheet = workbook.Sheets[sheetName]!;
  const rows = XLSX.utils.sheet_to_json<Record<string, unknown>>(sheet);

  if (rows.length === 0) throw new Error("File contains no data rows");

  const headers = Object.keys(rows[0]!);
  const columns = detectColumns(headers);
  const asinColumn = columns.asin;

  if (!asinColumn)
    throw new Error(
      `No ASIN column found. Available columns: ${headers.join(", ")}`,
    );

  logColumnDetection(headers, columns);

  const knownCols = getKnownColumns(columns);

  const products: ProductRecord[] = [];

  for (const row of rows) {
    const asin = parseAsin(row[asinColumn]);
    if (!asin) continue;

    const sourceUrl = getOptionalString(row, columns.sourceUrl);
    const asinLink = getOptionalString(row, columns.asinLink);
    const link = sourceUrl ?? asinLink ?? getOptionalString(row, columns.link);

    const extra = getExtraFields(row, headers, knownCols);
    const netProfitFromSheet = getOptionalNumber(row, columns.netProfit);
    const roiFromSheet = getOptionalNumber(row, columns.roi);

    products.push({
      asin,
      name: getOptionalString(row, columns.name) ?? "",
      unitCost: getOptionalNumber(row, columns.cost) ?? 0,
      brand: getOptionalString(row, columns.brand),
      category: getOptionalString(row, columns.category),
      amazonRank: getOptionalNumber(row, columns.amazonRank),
      avgPrice90FromSheet: getOptionalNumber(row, columns.avgPrice90),
      sellingPriceFromSheet: getOptionalNumber(row, columns.sellingPrice),
      fbaNet: getOptionalNumber(row, columns.fbaNet),
      grossProfit: getOptionalNumber(row, columns.grossProfit) ?? netProfitFromSheet,
      grossProfitPct:
        getOptionalNumber(row, columns.grossProfitPct) ?? roiFromSheet,
      netProfitFromSheet,
      roiFromSheet,
      moq: getOptionalNumber(row, columns.moq),
      moqCost: getOptionalNumber(row, columns.moqCost),
      totalQtyAvail: getOptionalNumber(row, columns.totalQty),
      link,
      asinLink,
      sourceUrl,
      supplier: getOptionalString(row, columns.supplier),
      promoCouponCode: getOptionalString(row, columns.promoCouponCode),
      notes: getOptionalString(row, columns.notes),
      leadDate: getOptionalString(row, columns.leadDate),
      ...extra,
    });
  }

  console.log(`Read ${products.length} valid products from ${filePath}`);
  return products;
}

function detectColumns(headers: string[]): ColumnMap {
  const columns = {} as ColumnMap;
  for (const key of Object.keys(COLUMN_CANDIDATES) as ColumnKey[]) {
    columns[key] = findColumn(headers, [...COLUMN_CANDIDATES[key]]);
  }
  return columns;
}

function logColumnDetection(headers: string[], columns: ColumnMap): void {
  console.log(`Found columns: ${headers.join(", ")}`);
  console.log(
    `Detected columns -> ASIN: ${columns.asin ?? "n/a"}, Name: ${columns.name ?? "n/a"}, Cost: ${columns.cost ?? "n/a"}, 90d Avg: ${columns.avgPrice90 ?? "n/a"}, Selling Price: ${columns.sellingPrice ?? "n/a"}, Net Profit: ${columns.netProfit ?? columns.grossProfit ?? "n/a"}, ROI: ${columns.roi ?? columns.grossProfitPct ?? "n/a"}, Source URL: ${columns.sourceUrl ?? "n/a"}, ASIN Link: ${columns.asinLink ?? "n/a"}`,
  );
}

function getKnownColumns(columns: ColumnMap): Set<string> {
  return new Set(Object.values(columns).filter((column): column is string => !!column));
}

function parseAsin(value: unknown): string | undefined {
  const asin = String(value ?? "")
    .trim()
    .toUpperCase();
  if (!asin || !ASIN_REGEX.test(asin)) {
    console.warn(`Skipping invalid ASIN: "${asin}"`);
    return undefined;
  }
  return asin;
}

function getOptionalString(
  row: Record<string, unknown>,
  column: string | undefined,
): string | undefined {
  if (!column) return undefined;
  return normalizeOptionalString(row[column]);
}

function getOptionalNumber(
  row: Record<string, unknown>,
  column: string | undefined,
): number | undefined {
  if (!column) return undefined;
  return parseOptionalNumber(row[column]);
}

function getExtraFields(
  row: Record<string, unknown>,
  headers: string[],
  knownCols: Set<string>,
): Record<string, unknown> {
  const extra: Record<string, unknown> = {};
  for (const header of headers) {
    if (!knownCols.has(header)) extra[header] = row[header];
  }
  return extra;
}

function findColumn(
  headers: string[],
  candidates: string[],
): string | undefined {
  const normalizedCandidates = new Set(candidates.map(normalizeHeader));

  for (const header of headers) {
    if (normalizedCandidates.has(normalizeHeader(header))) {
      return header;
    }
  }

  return undefined;
}

function normalizeHeader(value: string): string {
  return value
    .toLowerCase()
    .trim()
    .replace(/%/g, " pct ")
    .replace(/\$/g, " usd ")
    .replace(/[^a-z0-9]/g, "");
}

function normalizeOptionalString(value: unknown): string | undefined {
  if (value == null) return undefined;
  const s = String(value).trim();
  return s.length > 0 ? s : undefined;
}

function parseOptionalNumber(value: unknown): number | undefined {
  if (value == null || value === "") return undefined;
  const cleaned = String(value).trim().replace(/[$,%]/g, "").replace(/,/g, "");
  const parsed = Number(cleaned);
  return Number.isFinite(parsed) ? parsed : undefined;
}