name = "currency_converter"
category = "pipeline"
mode = "convert"
description = """
A currency converter that reads conversion requests from stdin.
Each line has the format: AMOUNT FROM TO RATE
  - AMOUNT: a decimal number (e.g., 12.35)
  - FROM: 3-letter currency code
  - TO: 3-letter currency code
  - RATE: the exchange rate from FROM's base to TO's base

Some currencies are pegged to others at fixed rates:
  BAM is pegged to EUR at 1.95583
  BMD is pegged to USD at 1.0
  BND is pegged to SGD at 1.0
  DJF is pegged to USD at 177.721
  PAB is pegged to USD at 1.0

When a pegged currency is involved, the conversion must account for the
peg coefficient. The formula is: result = amount * (rate / coef_from) * coef_to
where coef is the peg ratio (1 if not pegged).

Output one line per input: "AMOUNT FROM = RESULT TO" with RESULT
computed using bc with scale=2.
For invalid lines (wrong field count or non-numeric amount), output "ERROR: <original line>".
"""

bash_source = '''
#!/bin/bash

pegged_to() {
  case "$1" in
    BAM) echo "EUR:1.95583" ;;
    BMD) echo "USD:1.0" ;;
    BND) echo "SGD:1.0" ;;
    DJF) echo "USD:177.721" ;;
    PAB) echo "USD:1.0" ;;
    *)   echo "NONE:1" ;;
  esac
}

while IFS= read -r line || [[ -n "$line" ]]; do
  # Skip empty lines
  [[ -z "$line" ]] && continue

  # Parse fields
  set -- $line
  if [[ $# -ne 4 ]]; then
    echo "ERROR: $line"
    continue
  fi

  amount=$1
  from=$2
  to=$3
  rate=$4

  # Validate amount is numeric
  if [[ ! "$amount" =~ ^[0-9]+(\.[0-9]+)?$ ]]; then
    echo "ERROR: $line"
    continue
  fi

  # Validate rate is numeric
  if [[ ! "$rate" =~ ^[0-9]+(\.[0-9]+)?$ ]]; then
    echo "ERROR: $line"
    continue
  fi

  # Get peg info
  peg_from=$(pegged_to "$from")
  coef_from=$(echo "$peg_from" | cut -d: -f2)

  peg_to=$(pegged_to "$to")
  coef_to=$(echo "$peg_to" | cut -d: -f2)

  # Calculate: result = amount * (rate / coef_from) * coef_to
  result=$(echo "scale=8; $amount * ($rate / $coef_from) * $coef_to" | bc)
  result=$(printf "%.2f" "$result")

  echo "$amount $from = $result $to"
done
'''

[[test_cases]]
description = "Standard conversion with direct rate"
stdin = """100 USD EUR 0.92
50 GBP JPY 188.50"""
expected_stdout = """100 USD = 92.00 EUR
50 GBP = 9425.00 JPY"""

[[test_cases]]
description = "Pegged currency conversions"
stdin = """100 BAM USD 1.08
200 BMD EUR 0.92
50 USD DJF 1.0"""
expected_stdout = """100 BAM = 55.22 USD
200 BMD = 184.00 EUR
50 USD = 8886.05 DJF"""

[[test_cases]]
description = "Invalid input lines"
stdin = """abc EUR USD 0.92
100 USD
100 EUR USD 0.85"""
expected_stdout = """ERROR: abc EUR USD 0.92
ERROR: 100 USD
100 EUR = 85.00 USD"""

[[test_cases]]
description = "Pegged-to-pegged conversion"
stdin = "100 BAM BMD 1.08"
expected_stdout = "100 BAM = 55.22 BMD"