import { NextResponse } from "next/server";
import { db } from "@/db";
import { answers } from "@/db/schema";
import { inArray } from "drizzle-orm";
import { requireAdmin } from "@/lib/auth/auth";
import {
  getFilteredSubmissions,
  parseResultFilters,
} from "@/lib/form/admin-form-results";
import { answerCellValue } from "@/lib/form/form-answer-values";
import { stripHtml } from "@/lib/utils";

function csvCell(value: unknown) {
  const text = String(value ?? "");
  return `"${text.replaceAll('"', '""')}"`;
}

function safeFilename(value: string) {
  return (
    value
      .normalize("NFKD")
      .replace(/[^\p{L}\p{N}]+/gu, "-")
      .replace(/^-|-$/g, "")
      .slice(0, 60) || "form"
  );
}

function safeAsciiFilename(value: string) {
  return (
    value
      .normalize("NFKD")
      .replace(/[^\x00-\x7F]/g, "")
      .replace(/[^A-Za-z0-9]+/g, "-")
      .replace(/^-|-$/g, "")
      .slice(0, 60) || "form"
  );
}

function csvContentDisposition(title: string, date: string) {
  const unicodeFilename = `${safeFilename(title)}-responses-${date}.csv`;
  const asciiFilename = `${safeAsciiFilename(title)}-responses-${date}.csv`;

  return `attachment; filename="${asciiFilename}"; filename*=UTF-8''${encodeURIComponent(unicodeFilename)}`;
}

export async function GET(
  request: Request,
  { params }: { params: Promise<{ id: string }> }
) {
  await requireAdmin();
  const { id } = await params;
  const form = await db.query.forms.findFirst({
    where: (record, { eq }) => eq(record.id, id),
  });
  if (!form) {
    return NextResponse.json({ error: "Form not found" }, { status: 404 });
  }

  const url = new URL(request.url);
  const filters = parseResultFilters(
    Object.fromEntries(url.searchParams.entries())
  );
  const [{ rows }, questions] = await Promise.all([
    getFilteredSubmissions(id, filters, { paginate: false }),
    db.query.questions.findMany({
      where: (question, { eq }) => eq(question.formId, id),
      orderBy: (question, { asc }) => [asc(question.displayOrder)],
    }),
  ]);
  const answerRows =
    rows.length === 0
      ? []
      : await db
          .select()
          .from(answers)
          .where(inArray(answers.submissionId, rows.map((row) => row.id)));
  const answerMap = new Map(
    answerRows.map((answer) => [
      `${answer.submissionId}:${answer.questionId}`,
      { value: answer.value, imageCdnId: answer.imageCdnId ?? null },
    ])
  );
  const header = [
    "Respondent",
    "Discord ID",
    "Submitted at (Asia/Bangkok)",
    "Edit count",
    ...questions.map((question) => stripHtml(question.label)),
  ];
  const lines = [
    header.map(csvCell).join(","),
    ...rows.map((submission) =>
      [
        submission.userName || "Anonymous",
        submission.userDiscordId || "",
        submission.submittedAt.toLocaleString("en-GB", {
          timeZone: "Asia/Bangkok",
          hour12: false,
        }),
        Array.isArray(submission.editHistory)
          ? submission.editHistory.length
          : 0,
        ...questions.map((question) =>
          answerCellValue(
            answerMap.get(`${submission.id}:${question.id}`)?.value || "",
            question.type,
            answerMap.get(`${submission.id}:${question.id}`)?.imageCdnId
          )
        ),
      ]
        .map(csvCell)
        .join(",")
    ),
  ];
  const date = new Date().toISOString().slice(0, 10);

  return new NextResponse(`\uFEFF${lines.join("\r\n")}`, {
    headers: {
      "Content-Type": "text/csv; charset=utf-8",
      "Content-Disposition": csvContentDisposition(form.title, date),
    },
  });
}