import { NextRequest, NextResponse } from "next/server";
import { auth } from "@/auth";
import { db } from "@/lib/db";

const IMAGE_EXTS = new Set(["jpg", "jpeg", "png", "webp", "tiff", "tif", "avif"]);

export interface ThumbnailPreviewItem {
  fileName: string;
  stemName: string;
  shotCode: string | null;
  shotId: string | null;
  status: "match" | "no-match";
  currentThumbnailUrl: string | null;
}

function stem(fileName: string): string {
  const dot = fileName.lastIndexOf(".");
  return (dot > 0 ? fileName.slice(0, dot) : fileName).toLowerCase();
}

/**
 * POST /api/batch-upload/thumbnails
 * Body: { projectId: string; fileNames: string[] }
 */
export async function POST(req: NextRequest) {
  const session = await auth();
  if (!session?.user) return NextResponse.json({ error: "Unauthorized" }, { status: 401 });

  let body: { projectId?: string; fileNames?: string[] };
  try {
    body = await req.json();
  } catch {
    return NextResponse.json({ error: "Invalid JSON" }, { status: 400 });
  }

  const { projectId, fileNames } = body;
  if (!projectId || !Array.isArray(fileNames)) {
    return NextResponse.json({ error: "projectId and fileNames are required" }, { status: 400 });
  }

  // Only image files
  const imageFiles = fileNames.filter((f) => {
    const ext = f.split(".").pop()?.toLowerCase() ?? "";
    return IMAGE_EXTS.has(ext);
  });

  const shots = await db.shot.findMany({
    where: { projectId },
    select: { id: true, shotCode: true, thumbnailUrl: true },
  });

  // Build a lowercase map for case-insensitive matching
  const shotMap = new Map(shots.map((s) => [s.shotCode.toLowerCase(), s]));

  const items: ThumbnailPreviewItem[] = fileNames.map((fileName) => {
    const ext = fileName.split(".").pop()?.toLowerCase() ?? "";
    if (!IMAGE_EXTS.has(ext)) {
      return { fileName, stemName: stem(fileName), shotCode: null, shotId: null, status: "no-match" as const, currentThumbnailUrl: null };
    }
    const s = stem(fileName);
    const shot = shotMap.get(s) ?? null;
    return {
      fileName,
      stemName: s,
      shotCode: shot?.shotCode ?? null,
      shotId: shot?.id ?? null,
      status: shot ? "match" : "no-match",
      currentThumbnailUrl: shot?.thumbnailUrl ?? null,
    };
  });

  return NextResponse.json({ items });
}