#!/usr/bin/env bash

# embed.sh
# a simple script to handle embedding binary file contents into invocations
# of the CATSKILL_EMBED macro within catboot compiler source files.
# invoked with `./embed.sh source-1.c source-2.c header.h`
# outputs a file structure within the ./build/ directory matching the source
# directory, with the correct replacements done.
#
# Copyright (c) 2026, Mel G. <mel@rnrd.eu>
#
# SPDX-License-Identifier: MPL-2.0

set -euo pipefail

build_directory="./build/"

process_file() {
    local source_file="$1"
    local output_file="$build_directory/$source_file"

    mkdir -p $(dirname "$output_file")

    cp "$source_file" "$output_file"

    local embed_regex='CATSKILL_EMBED\("([^)]+)"\)' # const byte data[] = CATSKILL_EMBED("./file");
    local comment_regex='^\s*//' # // the macro CATSKILL_EMBED does...
    local define_regex='^\s*#define' # #define CATSKILL_EMBED {0}

    while IFS= read -r line; do
        # skip lines which are just comments mentioning the macro and
        # the line where we define the macro in the first place.
        if [[ $line =~ $comment_regex ]] || [[ $line =~ $define_regex ]]; then
            continue
        fi

        if [[ $line =~ $embed_regex ]]; then
            local pattern="${BASH_REMATCH[0]}"
            local embed_path="${BASH_REMATCH[1]}"

            # check that the file we want to embed actually exists
            if [ ! -f "$embed_path" ]; then
                echo "error: file not found: $embed_path (in $source_file)" >&2
                exit 1
            fi

            # get hexadecimal representation of file contents.
            # trim of start and end to get just the files, merge into one line and remove trailing whitespace.
            local hex_bytes=$(xxd -i "$embed_path" | tail -n+2 | head -n-2 | tr -d '\n' | xargs)

            # add in nil byte at the end of the binary data, for easier
            # interoperation with c-type strings
            local replacement="{ $hex_bytes, 0x00 }"

            local content=$(<"$output_file")
            content="${content//$pattern/$replacement}" # replace invocation with binary contents w/ bash.

            echo "$content" > "$output_file"
        fi
    done < "$source_file"
}

for source_file in "$@"; do
    process_file "$source_file"
done