import ExcelJS from "exceljs";
import { dirname } from "node:path";
import { mkdirSync } from "node:fs";
import type {
  KeepaUpcLookupStatus,
  SupplierAnalysisResult,
  SupplierVerdict,
} from "../types.ts";

export type SupplierExportSummary = {
  processedRows: number;
  resolvedRows: number;
  eligibleRows: number;
  verdictCounts: Record<SupplierVerdict, number>;
  unresolvedByStatus: Record<KeepaUpcLookupStatus, number>;
};

function pct(value: number | null): number | "" {
  return value == null ? "" : Math.round(value * 10_000) / 100;
}

function rowForResult(result: SupplierAnalysisResult) {
  const category =
    result.record.category ?? result.keepa?.categoryTree?.join(" > ") ?? "";
  const canSell =
    result.spApi?.canSell == null ? "" : result.spApi.canSell ? "yes" : "no";

  return {
    UPC: result.upc,
    ASIN: result.lookup.asin ?? "",
    Name: result.record.name,
    Brand: result.record.brand ?? "",
    Category: category,
    "Unit Cost": result.record.unitCost || "",
    "Sale Price": result.score.salePrice ?? "",
    "FBA Fee": result.score.fbaFee ?? "",
    Profit: result.score.profit ?? "",
    "Margin %": pct(result.score.margin),
    "ROI %": pct(result.score.roi),
    "BSR Current": result.keepa?.salesRank ?? "",
    "BSR 90d": result.keepa?.salesRankAvg90 ?? "",
    "Rank Drops 30d": result.keepa?.salesRankDrops30 ?? "",
    "Rank Drops 90d": result.keepa?.salesRankDrops90 ?? "",
    "Monthly Sold": result.keepa?.monthlySold ?? "",
    "Seller Count": result.keepa?.sellerCount ?? "",
    "Amazon Share 90d %": result.keepa?.amazonBuyboxSharePct90d ?? "",
    "Can Sell": canSell,
    Sellability: result.spApi?.sellabilityStatus ?? "",
    Score: result.score.score,
    Verdict: result.score.verdict,
    Reason: result.score.reason,
    "Lookup Status": result.lookup.status,
    "Candidate ASINs": result.lookup.candidateAsins.join(","),
    "Lookup Reason": result.lookup.reason ?? "",
  };
}

function addRowsSheet(
  workbook: ExcelJS.Workbook,
  name: string,
  rows: ReturnType<typeof rowForResult>[],
): void {
  const sheet = workbook.addWorksheet(name);
  const headers = rows[0] ? Object.keys(rows[0]) : Object.keys(rowForResult({
    upc: "",
    record: { name: "", unitCost: 0 },
    product: null,
    lookup: {
      requestedUpc: "",
      normalizedUpc: "",
      status: "not_found",
      asin: null,
      candidateAsins: [],
      keepaData: null,
    },
    keepa: null,
    spApi: null,
    score: {
      salePrice: null,
      fbaFee: null,
      profit: null,
      margin: null,
      roi: null,
      demandScore: 0,
      competitionPenalty: 1,
      score: 0,
      verdict: "SKIP",
      reason: "",
    },
    fetchedAt: "",
  }));

  sheet.columns = headers.map((header) => ({
    header,
    key: header,
    width: Math.min(Math.max(header.length + 4, 12), 28),
  }));
  sheet.addRows(rows);
  sheet.views = [{ state: "frozen", ySplit: 1 }];
  sheet.autoFilter = {
    from: { row: 1, column: 1 },
    to: { row: 1, column: headers.length },
  };
  sheet.getRow(1).font = { bold: true };
}

function addSummarySheet(
  workbook: ExcelJS.Workbook,
  summary: SupplierExportSummary,
): void {
  const sheet = workbook.addWorksheet("Summary");
  sheet.columns = [
    { header: "Metric", key: "Metric", width: 28 },
    { header: "Value", key: "Value", width: 18 },
  ];

  sheet.addRows([
    { Metric: "Processed Rows", Value: summary.processedRows },
    { Metric: "Resolved Rows", Value: summary.resolvedRows },
    { Metric: "Eligible Rows", Value: summary.eligibleRows },
    { Metric: "BUY", Value: summary.verdictCounts.BUY },
    { Metric: "WATCH", Value: summary.verdictCounts.WATCH },
    { Metric: "SKIP", Value: summary.verdictCounts.SKIP },
    { Metric: "Unresolved invalid_upc", Value: summary.unresolvedByStatus.invalid_upc },
    { Metric: "Unresolved not_found", Value: summary.unresolvedByStatus.not_found },
    { Metric: "Unresolved multiple_asins", Value: summary.unresolvedByStatus.multiple_asins },
    { Metric: "Unresolved request_failed", Value: summary.unresolvedByStatus.request_failed },
  ]);
  sheet.getRow(1).font = { bold: true };
}

export async function writeSupplierWorkbook(
  outputFile: string,
  results: SupplierAnalysisResult[],
  summary: SupplierExportSummary,
): Promise<void> {
  const outputDir = dirname(outputFile);
  if (outputDir && outputDir !== ".") {
    mkdirSync(outputDir, { recursive: true });
  }

  const workbook = new ExcelJS.Workbook();
  workbook.creator = "asin-check";
  workbook.created = new Date();

  const ranked = results
    .filter((result) => result.score.verdict !== "SKIP")
    .sort((a, b) => b.score.score - a.score.score)
    .map(rowForResult);
  const skipped = results
    .filter((result) => result.score.verdict === "SKIP")
    .map(rowForResult);

  addRowsSheet(workbook, "Ranked Leads", ranked);
  addRowsSheet(workbook, "Skipped", skipped);
  addSummarySheet(workbook, summary);

  await workbook.xlsx.writeFile(outputFile);
}