#!/usr/bin/env bash
set -euo pipefail

cd "$(dirname "$0")"

cache_dir=${CNC_SIM_PREFLIGHT_CACHE_DIR:-}
check_args=("$@")
if [[ "${1:-}" == "--cache-dir" ]]; then
    if [[ "$#" -lt 2 ]]; then
        echo "missing --cache-dir value" >&2
        exit 1
    fi
    cache_dir=$2
    shift 2
    check_args=("$@")
fi

manifest=${1:-}
require_complete=${2:-}
linuxcnc_root=${LINUXCNC_ROOT:-../linuxcnc}

if [[ -z "$cache_dir" ]]; then
    LINUXCNC_ROOT="$linuxcnc_root" ./check-linuxcnc-inputs.sh "${check_args[@]}"
    exit 0
fi
if [[ "$cache_dir" =~ [[:space:]] ]]; then
    echo "CNC_SIM_PREFLIGHT_CACHE_DIR must not contain whitespace: $cache_dir" >&2
    exit 1
fi

mkdir -p "$cache_dir"
cache_dir=$(cd "$cache_dir" && pwd)
if [[ "$cache_dir" == "/" ]]; then
    echo "CNC_SIM_PREFLIGHT_CACHE_DIR must not be the filesystem root" >&2
    exit 1
fi
exec 8>"$cache_dir/check-linuxcnc-inputs.lock"
flock 8

if [[ ! -d "$linuxcnc_root" ]]; then
    LINUXCNC_ROOT="$linuxcnc_root" ./check-linuxcnc-inputs.sh "${check_args[@]}"
    exit 0
fi
linuxcnc_root=$(cd "$linuxcnc_root" && pwd)

manifest_key=ROOT_ONLY
manifest_path=
if [[ -n "$manifest" && "$manifest" != "--root-only" ]]; then
    if [[ ! -f "$manifest" ]]; then
        LINUXCNC_ROOT="$linuxcnc_root" ./check-linuxcnc-inputs.sh "${check_args[@]}"
        exit 0
    fi
    manifest_path=$(cd "$(dirname "$manifest")" && pwd)/$(basename "$manifest")
    manifest_key=$(printf '%s' "$manifest_path" | sha256sum | awk '{ print $1 }')
fi

safe_require=${require_complete:-none}
safe_require=${safe_require//[^A-Za-z0-9_.-]/_}
args_key=$(
    {
        printf 'ARGS='
        printf ' %q' "${check_args[@]}"
        printf '\n'
    } | sha256sum | awk '{ print $1 }'
)
cache_file="$cache_dir/check-linuxcnc-inputs.${manifest_key}.${safe_require}.${args_key}.signature"
next_signature=$(mktemp "$cache_file.next.XXXXXX")

write_source_stat_signature() {
    local source_path
    [[ -z "$manifest_path" ]] && return 0
    while IFS=: read -r group path note extra; do
        case "$group" in
            ""|\#*)
                continue
                ;;
        esac
        [[ -z "${path:-}" ]] && continue
        source_path="$linuxcnc_root/$path"
        if [[ ! -f "$source_path" ]]; then
            return 1
        fi
        stat -c 'SOURCE=%n:%s:%y' "$source_path"
    done < "$manifest_path"
}

write_complete_mode_signature() {
    case "$require_complete" in
        --require-rs274-complete)
            find "$linuxcnc_root/src/emc/rs274ngc" -maxdepth 1 -type f \
                -printf 'RS274=%P:%s:%T@\n' | sort
            ;;
        --require-kinematics-complete)
            for source_dir in \
                "$linuxcnc_root/src/emc/kinematics" \
                "$linuxcnc_root/src/libnml/posemath" \
                "$linuxcnc_root/configs/sim"; do
                [[ -d "$source_dir" ]] || return 1
                find "$source_dir" -type f -printf "KIN=$source_dir/%P:%s:%T@\n" | sort
            done
            ;;
    esac
}

if ! {
    printf 'CHECK_SCRIPT='
    sha256sum check-linuxcnc-inputs.sh
    printf 'LINUXCNC_ROOT=%s\n' "$linuxcnc_root"
    printf 'ARGS='
    printf ' %q' "${check_args[@]}"
    printf '\n'
    if [[ -n "$manifest_path" ]]; then
        printf 'MANIFEST_PATH=%s\n' "$manifest_path"
        printf 'MANIFEST='
        sha256sum "$manifest_path"
        write_source_stat_signature
    fi
    write_complete_mode_signature
} > "$next_signature"; then
    rm -f "$next_signature"
    LINUXCNC_ROOT="$linuxcnc_root" ./check-linuxcnc-inputs.sh "${check_args[@]}"
    exit 0
fi

if [[ -f "$cache_file" ]] && cmp -s "$cache_file" "$next_signature"; then
    rm -f "$next_signature"
    exit 0
fi

LINUXCNC_ROOT="$linuxcnc_root" ./check-linuxcnc-inputs.sh "${check_args[@]}"
mv "$next_signature" "$cache_file"