#!/usr/bin/env dash

# shellcheck source=/dev/null
SHELL_LIBRARY_VERSION="2.0.13" . %SHELL_LIBRARY_PATH

# needed for help() and version
# shellcheck disable=2034
AUTHORS="Soispha"
# shellcheck disable=2034
YEARS="2024"
# shellcheck disable=2034
VERSION="1.0.0"

# NAME is from the wrapper
# shellcheck disable=SC2269
NAME="$NAME"

help() {
    cat <<EOF
Edit a file from the index. This script does not touch the unstaged variant of the file.

Usage:
    $NAME [OPTIONS] [--] FILES

OPTIONS:
    --
                            Ignore all flags after this point.

    --help | -h
                            Display this help and exit.

    --version | -v
                            Display version and copyright information and exit.
ARGUMENTS:
    FILES := [[ git diff --name-only --cached --diff-filter=AM ]]
                            The files to edit.

EOF
}

GIT_DIR="$(git rev-parse --show-toplevel)";
materialize_file() {
    git diff --cached "$1" > "$GIT_DIR/.git/EDIT_INDEX_PATCH"

    git add "$1"
    git restore --staged "$1"
    cat "$1" > "$GIT_DIR/.git/EDIT_INDEX_FILE"
    git restore "$1"

    git apply "$GIT_DIR/.git/EDIT_INDEX_PATCH"
    "$EDITOR" "$1"

    git add "$1"
    mv "$GIT_DIR/.git/EDIT_INDEX_FILE" "$1"
}

edit() {
    files_to_add="$(mktmp)";
    realpath --relative-to=. "$@" >"$files_to_add";

    index_files="$(mktmp)";
    git diff --name-only --cached --diff-filter=AM >"$index_files"

    while read -r file; do
        if grep -q "$file" "$files_to_add"; then
            sed -i "s|$file||" "$files_to_add";
            materialize_file "$file";
        fi
    done <"$index_files"

    files_to_check="$(mktmp)";
    clean "$files_to_add" > "$files_to_check"
    if [ "$(wc -l < "$files_to_check")" -gt 0 ]; then
        warn "Could not edit every file:"
        cat "$files_to_add";
    fi
}

for arg in "$@"; do
    case "$arg" in
        "--help" | "-h")
            help;
            ;;
        "--version" | "-v")
            version;
            ;;
        "--")
            break;
        ;;
    esac
done

edit "$@"

# vim: ft=sh