#! /bin/bash

set -e

STATION_ID="$1"  # ICAO designator. e.g. KJFK, KBOS

FILE_METAR_DECODED="$HOME/var/run/metar-${STATION_ID}-decoded"
FILE_TEMP_FAHRENHEIT="${FILE_METAR_DECODED}-temp-fahrenheit"
FILE_TEMP_CELSIUS="${FILE_METAR_DECODED}-temp-celsius"

(metar -d "$STATION_ID" 2>&1) > $FILE_METAR_DECODED  # TODO: Better error handling

awk \
    -v file_fahrenheit="$FILE_TEMP_FAHRENHEIT" \
    -v file_celsius="$FILE_TEMP_CELSIUS" \
    '
    /METAR pattern not found in NOAA data/ {
        failures++
    }

    /^Temperature/ {
        celsius = $3;
        fahrenheit = (celsius * (9 / 5)) + 32;
    }

    END {
        if (failures > 0) {
            print "--" > file_fahrenheit
            print "--" > file_celsius
        } else {
            print fahrenheit > file_fahrenheit
            print celsius    > file_celsius
        }
    }' \
    $FILE_METAR_DECODED