#!/bin/sh

set -eu

usage()
{
    printf 'Usage: %s --check|--write|--stage DIRECTORY\n' "${0##*/}" >&2
}

case ${1-}:$# in
    --check:1|--write:1)
        mode=$1
        ;;
    --stage:2)
        mode=$1
        stage_directory=$2
        ;;
    *)
        usage
        exit 2
        ;;
esac

script_dir=$(CDPATH='' cd "$(dirname "$0")" && pwd -P)
repo_root=$(CDPATH='' cd "$script_dir/.." && pwd -P)
status=0
temp_file=

trap 'if [ -n "$temp_file" ]; then rm -f "$temp_file"; fi' 0
trap 'exit 1' 1 2 3 15

has_expected_mode()
{
    mode_path=$1
    mode_match=$(find "$mode_path" -prune -type f -perm 0644 -print 2>/dev/null)
    [ "$mode_match" = "$mode_path" ]
}

replace_target()
{
    replace_source=$1
    replace_target=$2

    if [ -d "$replace_target" ]; then
        printf '%s cannot replace a directory\n' "$replace_target" >&2
        return 1
    fi
    temp_file=$(mktemp "$replace_target.tmp.XXXXXX")
    cp "$replace_source" "$temp_file"
    chmod 0644 "$temp_file"
    mv -f "$temp_file" "$replace_target"
    temp_file=
}

validate_source()
{
    source_relative=$1
    source_path=$repo_root/$source_relative
    if [ ! -f "$source_path" ] || [ -L "$source_path" ]; then
        printf '%s must be a regular file\n' "$source_relative" >&2
        status=1
    fi
}

sync_pair()
{
    source_relative=$1
    target_relative=$2
    source_path=$repo_root/$source_relative
    target_path=$repo_root/$target_relative

    content_matches=0
    if [ -f "$target_path" ] && [ ! -L "$target_path" ] && \
        cmp "$source_path" "$target_path" >/dev/null 2>&1; then
        content_matches=1
        if has_expected_mode "$target_path"; then
            return
        fi
    fi

    if [ "$mode" = "--check" ]; then
        printf '%s is out of date; run %s --write\n' \
            "$target_relative" "${0##*/}" >&2
        status=1
        return
    fi

    replace_target "$source_path" "$target_path"
    if [ "$content_matches" -eq 0 ]; then
        printf 'updated %s\n' "$target_relative"
    fi
}

validate_source xCAT/xcat.conf
validate_source xCAT/xcat.conf.apach24
if [ "$status" -ne 0 ]; then
    exit "$status"
fi

if [ "$mode" = "--stage" ]; then
    if [ ! -d "$stage_directory" ]; then
        printf '%s is not a directory\n' "$stage_directory" >&2
        exit 1
    fi
    replace_target "$repo_root/xCAT/xcat.conf" "$stage_directory/xcat.conf"
    replace_target "$repo_root/xCAT/xcat.conf.apach24" \
        "$stage_directory/xcat.conf.apach24"
else
    sync_pair xCAT/xcat.conf xCATsn/xcat.conf
    sync_pair xCAT/xcat.conf.apach24 xCATsn/xcat.conf.apach24
fi

exit "$status"