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

export async function GET(request: NextRequest) {
  const sql = getDb();
  const { searchParams } = new URL(request.url);
  const componentId = searchParams.get("componentId");
  const search = searchParams.get("search");
  const type = searchParams.get("type");
  const limit = Math.min(Number(searchParams.get("limit") || 50), 200);
  const offset = Number(searchParams.get("offset") || 0);

  let query = `
    SELECT
      st.*,
      c.name AS component_name,
      c.part_number,
      cat.name AS category_name
    FROM stock_transactions st
    JOIN components c ON st.component_id = c.id
    LEFT JOIN categories cat ON c.category_id = cat.id
    WHERE 1=1
  `;
  const params: (string | number)[] = [];
  let paramIdx = 1;

  if (componentId) {
    query += ` AND st.component_id = $${paramIdx++}`;
    params.push(Number(componentId));
  }

  if (search) {
    query += ` AND (c.name ILIKE $${paramIdx} OR c.part_number ILIKE $${paramIdx})`;
    params.push(`%${search}%`);
    paramIdx++;
  }

  if (type && type !== "all") {
    query += ` AND st.transaction_type = $${paramIdx++}`;
    params.push(type);
  }

  query += ` ORDER BY st.created_at DESC LIMIT $${paramIdx++} OFFSET $${paramIdx++}`;
  params.push(limit, offset);

  const rows = await sql(query, params);

  // Also get total count for pagination
  let countQuery = `
    SELECT COUNT(*) as total
    FROM stock_transactions st
    JOIN components c ON st.component_id = c.id
    WHERE 1=1
  `;
  const countParams: (string | number)[] = [];
  let countIdx = 1;

  if (componentId) {
    countQuery += ` AND st.component_id = $${countIdx++}`;
    countParams.push(Number(componentId));
  }
  if (search) {
    countQuery += ` AND (c.name ILIKE $${countIdx} OR c.part_number ILIKE $${countIdx})`;
    countParams.push(`%${search}%`);
    countIdx++;
  }
  if (type && type !== "all") {
    countQuery += ` AND st.transaction_type = $${countIdx++}`;
    countParams.push(type);
  }

  const countResult = await sql(countQuery, countParams);

  return NextResponse.json({
    transactions: rows,
    total: Number(countResult[0].total),
  });
}

export async function POST(request: NextRequest) {
  const sql = getDb();
  const body = await request.json();
  const {
    component_id,
    transaction_type,
    quantity,
    unit_cost,
    supplier,
    supplier_order_ref,
    notes,
  } = body;

  if (!component_id || !transaction_type || !quantity) {
    return NextResponse.json(
      { error: "component_id, transaction_type, and quantity are required" },
      { status: 400 }
    );
  }

  // Validate supplier_order_ref if provided - must match an existing PO
  if (supplier_order_ref && supplier_order_ref.trim()) {
    const poCheck = await sql(
      `SELECT id FROM supplier_pos WHERE po_number = $1`,
      [supplier_order_ref.trim()]
    );
    if (poCheck.length === 0) {
      return NextResponse.json(
        { error: `Purchase order "${supplier_order_ref}" not found. Please select a valid PO or leave the field empty.` },
        { status: 400 }
      );
    }
  }

  const total_cost = unit_cost ? Number(unit_cost) * Number(quantity) : null;

  // Insert the stock transaction record
  const insertParams = [
    component_id,
    transaction_type,
    Number(quantity),
    unit_cost ? Number(unit_cost) : null,
    total_cost,
    supplier || null,
    supplier_order_ref || null,
    notes || null,
  ];
  const rows = await sql(
    `INSERT INTO stock_transactions (component_id, transaction_type, quantity, unit_cost, total_cost, supplier, supplier_order_ref, notes)
     VALUES ($1, $2, $3, $4, $5, $6, $7, $8)
     RETURNING *`,
    insertParams
  );

  // Update the component's stock_quantity
  const qtyChange =
    transaction_type === "consumption"
      ? -Math.abs(Number(quantity))
      : Math.abs(Number(quantity));

  await sql(
    `UPDATE components SET stock_quantity = stock_quantity + $1, updated_at = NOW() WHERE id = $2`,
    [qtyChange, component_id]
  );

  return NextResponse.json(rows[0], { status: 201 });
}