import { NextRequest, NextResponse } from "next/server";
import { prisma, queryRaw } from "@/lib/db";
import { assignTransactionsToTrip, canAccessTransactions } from "@/lib/queries";
import { getCurrentUser } from "@/lib/auth";

export async function POST(req: NextRequest) {
  const user = await getCurrentUser(req);
  if (!user) return NextResponse.json({ error: "Unauthorized" }, { status: 403 });
  const body = await req.json();
  const { action, ids, category, merchant_normalized, splits, tag_id } = body as {
    action: string;
    ids: number[];
    category?: string;
    merchant_normalized?: string;
    splits?: { participant_id: number; share_percent: number }[];
    tag_id?: number;
  };

  if (!ids || !Array.isArray(ids) || ids.length === 0) {
    return NextResponse.json({ error: "ids required" }, { status: 400 });
  }

  if (!(await canAccessTransactions(user.id, ids.map(Number)))) {
    return NextResponse.json({ error: "Not found" }, { status: 404 });
  }

  if (action === "categorize" && category) {
    const ops = ids.map((id) =>
      prisma.transaction_overrides.upsert({
        where: { transaction_id: id },
        update: { category_override: category, updated_at: new Date() },
        create: { transaction_id: id, category_override: category },
      })
    );
    await prisma.$transaction(ops);
    return NextResponse.json({ updated: ids.length });
  }

  if (action === "normalize" && merchant_normalized) {
    const ops = ids.map((id) =>
      prisma.transaction_overrides.upsert({
        where: { transaction_id: id },
        update: { merchant_normalized, updated_at: new Date() },
        create: { transaction_id: id, merchant_normalized },
      })
    );
    await prisma.$transaction(ops);
    return NextResponse.json({ updated: ids.length });
  }

  if (action === "split" && Array.isArray(splits) && splits.length > 0) {
    const total = splits.reduce((s, x) => s + x.share_percent, 0);
    if (Math.abs(total - 100) > 0.01) {
      return NextResponse.json({ error: "Shares must sum to 100%" }, { status: 400 });
    }
    await prisma.$transaction(
      ids.flatMap((id) => [
        prisma.transaction_splits.deleteMany({ where: { transaction_id: id } }),
        prisma.transaction_splits.createMany({
          data: splits.map((s) => ({
            transaction_id: id,
            participant_id: s.participant_id,
            share_percent: s.share_percent,
          })),
        }),
      ])
    );
    return NextResponse.json({ updated: ids.length });
  }

  if ((action === "tag" || action === "untag") && tag_id) {
    if (action === "tag") {
      for (const id of ids) {
        await queryRaw(
          `INSERT INTO transaction_tags (transaction_id, tag_id) VALUES ($1, $2) ON CONFLICT DO NOTHING`,
          [id, tag_id]
        );
      }
    } else {
      await queryRaw(
        `DELETE FROM transaction_tags WHERE transaction_id = ANY($1::int[]) AND tag_id = $2`,
        [ids, tag_id]
      );
    }
    return NextResponse.json({ updated: ids.length });
  }

  if (action === "assign_trip") {
    const { trip_id } = body as { ids: number[]; trip_id: number | null };
    await assignTransactionsToTrip(trip_id, ids);
    return NextResponse.json({ updated: ids.length });
  }

  return NextResponse.json({ error: "Invalid action" }, { status: 400 });
}