#!/bin/sh

CONFIG_DIR="${XDG_CONFIG_HOME:-$HOME/.config}/gitignore"

usage() {
    cat <<EOF
Usage:
  gitignore TEMPLATE...
      Create a new .gitignore from templates.

  gitignore -f TEMPLATE...
      Overwrite existing .gitignore.

  gitignore --add TEMPLATE...
      Append templates to existing .gitignore.

  gitignore --list
      List available templates.

  gitignore --show TEMPLATE
      Show a template.

Templates are searched in:
  $CONFIG_DIR
EOF
}

list_templates() {
    [ -d "$CONFIG_DIR" ] || exit 0

    find "$CONFIG_DIR" -type f -exec basename {} \; | sort
}

show_template() {
    file="$CONFIG_DIR/$1"

    if [ ! -f "$file" ]; then
        echo "Unknown template: $1" >&2
        exit 1
    fi

    cat "$file"
}

append_template() {
    template="$1"
    file="$CONFIG_DIR/$template"

    if [ ! -f "$file" ]; then
        echo "Unknown template: $template" >&2
        exit 1
    fi

    {
        echo
        echo "# --- $template ---"
        cat "$file"
    } >> .gitignore
}

create_gitignore() {
    mode="$1"
    shift

    if [ -f .gitignore ] && [ "$mode" != "force" ]; then
        echo ".gitignore already exists." >&2
        echo "Use -f to overwrite or --add to append." >&2
        exit 1
    fi

    : > .gitignore

    for template in "$@"; do
        append_template "$template"
    done
}

add_templates() {
    [ -f .gitignore ] || touch .gitignore

    for template in "$@"; do
        append_template "$template"
    done
}

case "$1" in
    --help|-h)
        usage
        ;;

    --list)
        list_templates
        ;;

    --show)
        shift

        [ $# -eq 1 ] || {
            echo "--show requires exactly one template" >&2
            exit 1
        }

        show_template "$1"
        ;;

    --add)
        shift

        [ $# -gt 0 ] || {
            echo "No templates specified" >&2
            exit 1
        }

        add_templates "$@"
        ;;

    -f)
        shift

        [ $# -gt 0 ] || {
            echo "No templates specified" >&2
            exit 1
        }

        create_gitignore force "$@"
        ;;

    "")
        usage
        exit 1
        ;;

    *)
        create_gitignore normal "$@"
        ;;
esac