# Transaction Event Listener - Ecto.CastError Fix Summary

## Problem Analysis
The error was: `Ecto.CastError: expected params to be a map with atoms or string keys, got a map with mixed keys`

**Root Cause:**
- The `transaction_event_listener.ex` was using **string keys** in the `temp_txn_params` map
- The `Acquirer.create_temp_transaction()` function adds **atom keys** (`:created_dateTime`, `:updated_dateTime`)
- This created a mixed-key map that Ecto cannot process

## Changes Made

### 1. Fixed `create_temp_sale_transaction` function
**Before (String Keys):**
```elixir
temp_txn_params = %{
  "temp_transaction_id" => generate_temp_transaction_id(),
  "terminal_id" => terminal_config.tid,
  "merchant_id" => terminal_config.mid,
  "card_number" => pan,
  "amount" => parse_decimal_amount(amount),
  # ... more string keys
}
```

**After (Atom Keys - Matching transaction_processor.ex):**
```elixir
temp_txn_params = %{
  s_tid: s_tid,
  s_mid: s_mid,
  s_tid_stan: s_tid_stan,
  total_amount: parse_decimal_amount(amount),
  # ... all atom keys matching the schema
}
```

### 2. Fixed `create_reversal_record` function
**Before (String Keys):**
```elixir
reversal_attrs = %{
  "original_transaction_id" => get_transaction_id(original_txn),
  "terminal_id" => terminal_config.tid,
  # ... string keys
}
```

**After (Atom Keys - Matching schema and transaction_processor.ex):**
```elixir
reversal_attrs = %{
  original_transaction_id: get_transaction_id(original_txn),
  original_s_tid: original_txn.s_tid,
  original_s_mid: original_txn.s_mid,
  # ... all atom keys matching PosReversal schema
}
```

### 3. Updated `parse_decimal_amount` to use Decimal type
**Before (Integer):**
```elixir
case Integer.parse(amount) do
  {amount_int, ""} -> amount_int
  _ -> 0
end
```

**After (Decimal - Matching schema):**
```elixir
case Integer.parse(amount) do
  {amount_int, ""} -> Decimal.new(amount_int)
  _ -> Decimal.new(0)
end
```

### 4. Added Decimal alias
```elixir
alias Decimal
```

### 5. Updated `find_original_transaction` to match transaction_processor.ex pattern
- Now searches both temp and final transaction tables
- Uses consistent error handling patterns

### 6. Cleaned up unused functions
- Removed `generate_temp_transaction_id()` (not needed with new pattern)
- Removed `parse_transaction_time()` (not used)

## Key Alignment with transaction_processor.ex

✅ **Consistent Parameter Structure**: Both files now use the same atom-key pattern  
✅ **Schema Compliance**: All parameters match the actual database schema fields  
✅ **Decimal Amounts**: Using `Decimal.new()` for proper amount handling  
✅ **Error Handling**: Consistent error patterns between event listener and processor  
✅ **Field Names**: Matching actual schema field names (`s_tid`, `s_mid`, `total_amount`, etc.)  

## Result
- **Ecto.CastError eliminated**: All parameter maps now have consistent atom keys
- **Schema compliance**: Parameters match the actual database schema expectations
- **Pattern consistency**: Event listener now follows the same patterns as transaction_processor.ex
- **Better maintainability**: Consistent code patterns across YSP modules

## Test Verification
The fix was verified with a test script that confirms:
- All parameter keys are atoms (no mixing)
- Timestamp merge works correctly
- Final parameter structure is Ecto-compatible