finance/src/pages/api/transactions/[id]/index.ts

import type { APIRoute } from 'astro';
import { transactions, accounts } from '../../../../data/store';
import type { Transaction } from '../../../../types';

export const PUT: APIRoute = async ({ request, params }) => {
  const { id } = params;

  if (!id) {
    return new Response(JSON.stringify({ error: 'Transaction ID is required' }), {
      status: 400,
      headers: { 'Content-Type': 'application/json' },
    });
  }

  try {
    const updates = (await request.json()) as Partial<Transaction>;
    const transactionIndex = transactions.findIndex((t) => t.id === id);

    if (transactionIndex === -1) {
      return new Response(JSON.stringify({ error: 'Transaction not found' }), {
        status: 404,
        headers: { 'Content-Type': 'application/json' },
      });
    }

    const oldTransaction = transactions[transactionIndex];

    // Get the old account first
    const oldAccount = accounts.find((a) => a.id === oldTransaction.accountId);
    if (!oldAccount) {
      return new Response(JSON.stringify({ error: 'Account not found' }), {
        status: 404,
        headers: { 'Content-Type': 'application/json' },
      });
    }

    // If account is changing, validate new account exists
    let newAccount = oldAccount;
    if (updates.accountId && updates.accountId !== oldTransaction.accountId) {
      const foundAccount = accounts.find((a) => a.id === updates.accountId);
      if (!foundAccount) {
        return new Response(JSON.stringify({ error: 'Account not found' }), {
          status: 404,
          headers: { 'Content-Type': 'application/json' },
        });
      }
      newAccount = foundAccount;
    }

    // First, remove the old transaction's effect on the old account
    oldAccount.balance -= oldTransaction.amount;

    // Create updated transaction
    const updatedTransaction: Transaction = {
      ...oldTransaction,
      ...updates,
      id: id, // Ensure ID doesn't change
    };

    // Then add the new transaction's effect to the appropriate account
    if (newAccount === oldAccount) {
      // If same account, just add the new amount
      oldAccount.balance += updatedTransaction.amount;
    } else {
      // If different account, add to the new account
      newAccount.balance += updatedTransaction.amount;
    }

    // Update transaction in array
    transactions[transactionIndex] = updatedTransaction;

    return new Response(JSON.stringify(updatedTransaction), {
      status: 200,
      headers: { 'Content-Type': 'application/json' },
    });
  } catch (error) {
    return new Response(JSON.stringify({ error: 'Invalid request body' }), {
      status: 400,
      headers: { 'Content-Type': 'application/json' },
    });
  }
};

export const DELETE: APIRoute = async ({ params }) => {
  const { id } = params;

  if (!id) {
    return new Response(JSON.stringify({ error: 'Transaction ID is required' }), {
      status: 400,
      headers: { 'Content-Type': 'application/json' },
    });
  }

  const transactionIndex = transactions.findIndex((t) => t.id === id);

  if (transactionIndex === -1) {
    return new Response(JSON.stringify({ error: 'Transaction not found' }), {
      status: 404,
      headers: { 'Content-Type': 'application/json' },
    });
  }

  const transaction = transactions[transactionIndex];
  const account = accounts.find((a) => a.id === transaction.accountId);

  if (!account) {
    return new Response(JSON.stringify({ error: 'Account not found' }), {
      status: 404,
      headers: { 'Content-Type': 'application/json' },
    });
  }

  // Update account balance
  account.balance -= transaction.amount;

  // Remove transaction from array
  transactions.splice(transactionIndex, 1);

  return new Response(null, { status: 204 });
};