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

interface SplitInput {
  participant_id: number;
  share_percent: number;
}

interface SplitRow {
  id: number;
  transaction_id: number;
  participant_id: number;
  name: string;
  share_percent: number;
  settled: boolean;
  settled_at: string | null;
  created_at: string;
}

export async function GET(
  _req: NextRequest,
  { params }: { params: Promise<{ id: string }> }
) {
  const { id } = await params;
  const splits = await queryRaw<SplitRow>(
    `SELECT ts.*, p.name
     FROM transaction_splits ts
     JOIN participants p ON p.id = ts.participant_id
     WHERE ts.transaction_id = $1
     ORDER BY p.name`,
    [Number(id)]
  );
  return NextResponse.json(splits);
}

export async function POST(
  req: NextRequest,
  { params }: { params: Promise<{ id: string }> }
) {
  const { id } = await params;
  const transactionId = Number(id);
  const { splits } = (await req.json()) as { splits: SplitInput[] };

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

  const total = splits.reduce((sum, s) => sum + Number(s.share_percent), 0);
  if (Math.abs(total - 100) > 0.01) {
    return NextResponse.json(
      { error: `Shares must sum to 100%, got ${total}%` },
      { status: 400 }
    );
  }

  // Replace all splits for this transaction atomically
  await prisma.$transaction([
    prisma.transaction_splits.deleteMany({ where: { transaction_id: transactionId } }),
    ...splits.map((s) =>
      prisma.transaction_splits.create({
        data: {
          transaction_id: transactionId,
          participant_id: s.participant_id,
          share_percent: s.share_percent,
        },
      })
    ),
  ]);

  const result = await queryRaw<SplitRow>(
    `SELECT ts.*, p.name FROM transaction_splits ts
     JOIN participants p ON p.id = ts.participant_id
     WHERE ts.transaction_id = $1 ORDER BY p.name`,
    [transactionId]
  );

  return NextResponse.json(result);
}