progress

#!/usr/bin/env bash

set -euo pipefail

if [[ ! "$BASH_VERSION" > "5.2.0" ]]; then
    >&2 echo "Requires bash 5.2 or above. Sorry."
    exit 1
fi

TREASURE=TREASURE

here=$(pwd)

puzzle_dir="$here/puzzle"
secrets_dir="$here/.found"
hints_dir="$here/.hints"

verbose="no"
show_hint="no"

while [[ $# -gt 0 ]]; do
    case "$1" in
        -c | --clean)
            rm -rf "$secrets_dir"
            shift;
            ;;
        -v | --verbose)
            verbose=yes
            shift;
            ;;
        -h | --hint)
            show_hint=yes
            shift
            ;;
        *)
            >&2 echo "Unknown option: $1"
            exit 1
            ;;
    esac
done

script_name() {
    printf "%s/clue-%03d.sh" "$here" "$1"
}

answer_name() {
    printf "%s/secret-%03d.txt" "$secrets_dir" "$1"
}

hint_name() {
    printf "%s/hint-%03d.txt" "$hints_dir" "$1"
}

# Get the clue that the current script is based on. Assumes that we've already
# run the previous script so the answer file exists.
get_clue() {
    i="$1"
    if [[ "$i" -eq 0 ]]; then
        cat "$puzzle_dir/.first-clue"
    else
        secret=$(< "$(answer_name $((i - 1)))")
        echo "${secret#*: }"
    fi
}

# Get the secret for step i by running the script or loading the cached answer.
get_secret() {
    script=$(script_name "$1")
    answer=$(answer_name "$1")

    # Run the script if needed (no answer or out of date answer)
    if [[ ! -e "$answer" || "$script" -nt "$answer" ]]; then
        if [[ "$verbose" = "yes" ]]; then
            >&2 echo "Running $(basename "$script")"
        fi
        if ! "$script" > "$answer"; then
            rm -f "$answer"
            return 1
        fi
    else
        if [[ "$verbose" = "yes" ]]; then
            >&2 echo "$(basename "$answer") up to date"
        fi
    fi

    # Should be a file by now.
    if [[ -e "$answer" ]]; then
        cat "$answer"
        return 0
    else
        >&2 echo "Weird. No answer file."
        return 1
    fi
}

decrypt_treasure() {
    local keygen_opts
    read -ra keygen_opts < "$puzzle_dir/.keygen-opts"
    find "$secrets_dir" -type f | sort | xargs cut -d : -f 1 | \
        openssl dgst -sha256 -binary | \
        openssl enc -d "${keygen_opts[@]}" \
                -in "$puzzle_dir/.treasure.enc" \
                -out "$TREASURE" \
                -pass stdin 2> /dev/null
}

complete=0

if [[ -d "$puzzle_dir" ]]; then

    next_clue=$(get_clue "0")

    readarray -t hashes < <(tac "$puzzle_dir/.hashes")

    mkdir -p "$secrets_dir"

    i=0
    while [[ "$i" -lt "${#hashes[@]}" ]]; do
        script=$(script_name "$i")
        if [[ -e "$script" ]]; then
            if secret=$(get_secret "$i"); then
                check=$(sha1sum <<< "$secret" | cut -c -40)
                if [[ "${hashes[$i]}" = "$check" ]]; then
                    printf "✅ %s (%s)\n" "$(get_clue "$i")" "$(basename "$script")"
                    complete=$((complete + 1))
                    next_clue="${secret#*: }"
                else
                    printf "❌ %s (%s)\n" "$(get_clue "$i")" "$(basename "$script")"
                    break
                fi
            else
                printf "💣 Problem running %s\n" "$script"
                next_clue="$(get_clue "$i")"
                break
            fi
        else
            break
        fi
        ((i += 1))
    done

    # i is now at the index of the next puzzle or the length of hashes if all
    # puzzles have been solved.

    echo
    echo "$complete of ${#hashes[@]} complete"

    if [[ "$complete" -lt "${#hashes[@]}" ]]; then
        if [[ -n "$next_clue" ]]; then
            echo
            echo "Next clue: $next_clue"
            echo
            if [[ "$show_hint" = "yes" ]]; then
                hint=$(hint_name "$i")
                if [[ -e "$hint" ]]; then
                    cat "$hint"
                else
                    echo "Sorry, no hint available."
                fi
                echo
            fi
            next_script="$(script_name "$complete")"
            if [[ ! -e "$next_script" ]]; then
                cat <<EOF > "$next_script"
#!/usr/bin/env bash

set -euo pipefail

EOF
                chmod +x "$next_script"
            fi
            echo "Write your code to extract this secret in ${next_script#"$here/"}"
            echo
        fi
    else
        if [[ -e "$TREASURE" ]] || decrypt_treasure; then
            echo
            echo "You found the treasure!"
            echo
            cat "$TREASURE"
        else
            rm -f "$TREASURE"
            >&2 echo
            >&2 echo "Uh oh. Your treasure seems to be damaged."
        fi
        echo
    fi
else
    echo "No puzzle directory!"
    exit 1
fi