import { NextRequest, NextResponse } from "next/server";
import { prisma } from "@/lib/db";
import { Prisma } from "@prisma/client";
import * as XLSX from "xlsx";

export async function GET(req: NextRequest) {
  try {
    const { searchParams } = new URL(req.url);
    const search = searchParams.get("search") || "";
    const statuses = searchParams.getAll("status");
    const sourceTabs = searchParams.getAll("sourceTab");
    const priorities = searchParams.getAll("priority");
    const hasEmail = searchParams.get("hasEmail");
    const emailOnly = searchParams.get("emailOnly") === "true";
    const format = searchParams.get("format") || "csv"; // "csv" | "xlsx"

    const where: Prisma.LeadWhereInput = {};
    if (search) {
      where.OR = [
        { domain: { contains: search } },
        { companyName: { contains: search } },
        { contactName: { contains: search } },
        { email: { contains: search } },
      ];
    }
    if (statuses.length > 0) where.status = { in: statuses };
    if (sourceTabs.length > 0) where.sourceTab = { in: sourceTabs };
    if (priorities.length > 0) where.priority = { in: priorities };
    if (hasEmail === "yes" || emailOnly) where.email = { not: null };
    else if (hasEmail === "no") where.email = null;

    const leads = await prisma.lead.findMany({
      where,
      orderBy: { capturedAt: "desc" },
      take: 10000,
    });

    const rows = leads.map(l => ({
      "Unternehmen":   l.companyName || "",
      "Domain":        l.domain || "",
      "Kontaktname":   l.contactName || "",
      "Position":      l.contactTitle || "",
      "E-Mail":        l.email || "",
      "Telefon":       l.phone || "",
      "Adresse":       l.address || "",
      "LinkedIn":      l.linkedinUrl || "",
      "Branche":       l.industry || "",
      "Suchbegriff":   l.sourceTerm || "",
      "Tags":          l.tags ? (JSON.parse(l.tags) as string[]).join(", ") : "",
      "Erfasst am":    new Date(l.capturedAt).toLocaleDateString("de-DE", { day: "2-digit", month: "2-digit", year: "numeric" }),
    }));

    const filename = `onyva-leads-vault-${new Date().toISOString().split("T")[0]}`;

    if (format === "xlsx") {
      const ws = XLSX.utils.json_to_sheet(rows);

      // Column widths (one per column)
      ws["!cols"] = [
        { wch: 30 }, // Unternehmen
        { wch: 28 }, // Domain
        { wch: 24 }, // Kontaktname
        { wch: 24 }, // Position
        { wch: 34 }, // E-Mail
        { wch: 18 }, // Telefon
        { wch: 36 }, // Adresse
        { wch: 36 }, // LinkedIn
        { wch: 22 }, // Branche
        { wch: 30 }, // Suchbegriff
        { wch: 28 }, // Tags
        { wch: 14 }, // Erfasst am
      ];

      // Freeze header row
      ws["!freeze"] = { xSplit: 0, ySplit: 1 };

      // Autofilter across all columns
      const colCount = Object.keys(rows[0] ?? {}).length || 17;
      const lastCol = String.fromCharCode(64 + colCount);
      ws["!autofilter"] = { ref: `A1:${lastCol}1` };

      const wb = XLSX.utils.book_new();
      XLSX.utils.book_append_sheet(wb, ws, "LeadVault");

      const arr = XLSX.write(wb, { type: "array", bookType: "xlsx" }) as number[];

      return new NextResponse(new Uint8Array(arr).buffer, {
        headers: {
          "Content-Type": "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
          "Content-Disposition": `attachment; filename="${filename}.xlsx"`,
        },
      });
    }

    // CSV — UTF-8 BOM so Excel opens it correctly
    const colKeys = Object.keys(rows[0] ?? {});
    const escape = (v: string) =>
      v.includes(",") || v.includes('"') || v.includes("\n") || v.includes("\r")
        ? `"${v.replace(/"/g, '""')}"`
        : v;

    const csv =
      "\uFEFF" +
      [
        colKeys.map(escape).join(","),
        ...rows.map(r => colKeys.map(h => escape(String(r[h as keyof typeof r] ?? ""))).join(",")),
      ].join("\r\n");

    return new NextResponse(csv, {
      headers: {
        "Content-Type": "text/csv; charset=utf-8",
        "Content-Disposition": `attachment; filename="${filename}.csv"`,
      },
    });
  } catch (err) {
    console.error("GET /api/leads/export error:", err);
    return NextResponse.json({ error: "Export failed" }, { status: 500 });
  }
}