check_required_files_present

#!/usr/bin/env bash
missing_files=0
unneeded_files=0
verbose_progress='false'

if [[ ! -d exercises ]]; then
    echo '"exercises" directory not found, make sure you are running from the repository root' >&2
    exit 1
fi

function show_progress {
    if [[ "${verbose_progress}" == 'true' ]]; then
        printf '.'
    fi
}

function require_file {
    local filename=$1
    if [[ ! -f "${filename}" ]]; then
        echo "required file missing: ${filename}" >&2
        (( ++missing_files ))
    fi
}

function reject_file {
    filename=$1
    if [[ -f "${filename}" ]]; then
        echo "unneeded file should be removed: ${filename}" >&2
        (( ++unneeded_files ))
    fi
}

function require_file_or_alternative {
    filename=$1
    alternative_filename=$2
    if [[ ! -f "${filename}" && ! -f "${alternative_filename}" ]]; then
        echo "required file missing: ${filename} or ${alternative_filename}" >&2
        (( ++missing_files ))
    elif [[ -f "${filename}" && -f "${alternative_filename}" ]]; then
        echo "one of these two files should be removed: ${filename} or ${alternative_filename}" >&2
        (( ++unneeded_files ))
    fi
}

function check_directory {
    directory=$1
    for exercise_directory in "${directory}"/*; do
        show_progress

        # only two possibilities are allowed:
        # 1. legacy: only description.md
        # 2. migrated to new format: description.md is gone,
        #    and only instructions.md and introduction.md exist.
        desc="${exercise_directory}/description.md"
        inst="${exercise_directory}/instructions.md"
        intro="${exercise_directory}/introduction.md"
        require_file_or_alternative "${desc}" "${inst}"
        if [[ -f "${inst}" ]]; then
            require_file "${intro}"
        elif [[ -f "${desc}" ]]; then
            reject_file "${intro}"
        fi

        require_file "${exercise_directory}/metadata.toml"
    done

}

if [[ "$1" == "-p" || "$1" == "--progress" ]]; then
    verbose_progress="true"
fi

check_directory 'exercises'

if [[ "${verbose_progress}" == 'true' ]]; then
    echo
    echo "done: ${missing_files} files missing and ${unneeded_files} unneeded files."
fi

if (( missing_files || unneeded_files )); then
    exit 1
else
    exit 0
fi