#!/bin/bash

set -e

usage() {
    echo usage:
    echo "    BT=/path/to/AppleCommander-bastools-bt.jar $0 basic-program.bas"
    exit 1
}

echo_run() {
    echo "$@"
    "$@"
}

main() {
    if [[ -z "$BT" ]]; then
        usage
    fi
    if [[ $# -ne 1 ]]; then
        usage
    fi
    local file=$1
    local name=${file%.*}
    local ext=${file##*.}
    if [[ "$ext" -ne bas ]]; then
        usage
    fi

    echo_run java -jar "$BT" "$file" -o "$name".tok

    # Note that in the header format, the length field is deliberately
    # off-by-one. I haven't come across any docs mentioning this (though I
    # haven't explicitly looked), but I did verify it experimentally.
    #
    # In particular, this means that it's possible for the BASIC code segment
    # to contain exactly 64KiB of data, but it cannot be empty.
    echo Creating header file...
    local len=$(wc --bytes "$name".tok | cut -d' ' -f1)
    if [[ "$len" -eq 0 ]]; then
        echo "error: can't encode empty segment"
        exit 1
    fi
    len=$((len - 1))  # !!!
    local len_low=$(printf '%02x' $(($len % 256)))
    local len_high=$(printf '%02x' $(($len / 256)))
    echo -en "\\x$len_low\\x$len_high\\x55" > "$name".hdr

    echo_run c2t -2 "$name".hdr,0 "$name".tok,0 "$name".wav

    echo Saved to "$name".wav
    echo
    echo '*******************************************'
    echo '* Ignore the above instructions. Instead: *'
    echo '*******************************************'
    echo
    echo Type LOAD from the BASIC prompt on the Apple II,
    echo connect an audio cable, and play the .wav file.
}

main "$@"