#!/usr/bin/env bash
# ==============================================================
#  appinstall - Run an AppImage from the current directory
# --------------------------------------------------------------
#  Author   : Kris Yotam
#  Contact  : krisyotam@protonmail.com
#  License  : GNU GPLv3
#  Created  : 2025-10-04
# --------------------------------------------------------------
#  Description:
#    - Finds *.AppImage files in a directory (current by default),
#      makes them executable, and prompts the user to select one
#      using fzf. If fzf is not available, the script launches the
#      first found AppImage.
#
#    - This file is intended to be installed in a user's bin
#      directory (e.g. ~/.local/bin/appinstall) and used as a
#      small helper to run AppImage files.
#
#  Usage:
#    appinstall [DIRECTORY]
#    appinstall --help
#
#  Notes:
#    - Uses bash-specific behavior (nullglob). Keeps behavior
#      simple and robust against directories with no AppImage files.
# ==============================================================

set -euo pipefail

# -------------------- Configuration (like config.py header) -----------------
# Default directory to scan for AppImage files. Can be overridden by
# passing a directory path as the first argument to the script.
DEFAULT_DIR="."

# fzf prompt text
FZF_PROMPT="Select AppImage: "

# ---------------------------------------------------------------------------

print_help() {
    cat <<'HELP'
appinstall - Run an AppImage from the current directory

Usage:
  appinstall [DIRECTORY]
  appinstall --help

If DIRECTORY is omitted the current working directory is used. The
script will make all found *.AppImage files executable before offering a
selection (via fzf when available). If fzf is not installed the script
will run the first AppImage found.
HELP
}

# Make an array of AppImage files in the provided directory.
# Uses bash nullglob so that when there are no matches the array is empty.
find_appimages() {
    local dir="$1"
    # enable nullglob so the pattern expands to zero elements if no match
    shopt -s nullglob
    local -a arr=("$dir"/*.AppImage)
    shopt -u nullglob
    printf '%s\n' "${arr[@]}"
}

main() {
    # Handle help request
    if [ "${1:-}" = "--help" ] || [ "${1:-}" = "-h" ]; then
        print_help
        return 0
    fi

    local dir="${1:-$DEFAULT_DIR}"

    # Collect AppImage files (full paths)
    IFS=$'\n' read -r -d '' -a apps < <(find_appimages "$dir" | sed '/^$/d' && printf '\0') || true

    if [ ${#apps[@]} -eq 0 ]; then
        printf "No AppImage files found in %s\n" "$dir" >&2
        return 1
    fi

    # Make each AppImage executable (best-effort)
    for f in "${apps[@]}"; do
        chmod +x -- "$f" 2>/dev/null || true
    done

    # If fzf is available, let the user choose; otherwise pick the first
    if command -v fzf >/dev/null 2>&1; then
        # Present only basenames to the user and map selection back to the full path
        local sel_basename
        sel_basename=$(printf '%s\n' "${apps[@]##*/}" | fzf --prompt="$FZF_PROMPT") || sel_basename=''

        if [ -z "$sel_basename" ]; then
            # no selection (user pressed ESC or similar)
            printf "No selection made. Exiting.\n"
            return 0
        fi

        local selected_path
        # If the user supplied a directory path, selected basename may or may not include the dir
        if [[ "$dir" == "." ]]; then
            selected_path="$sel_basename"
        else
            selected_path="$dir/$sel_basename"
        fi

        # Run the selected AppImage (replace this shell with the AppImage)
        exec -- "$selected_path"
    else
        # fzf not installed - run the first found AppImage
        printf "fzf not found; launching first AppImage: %s\n" "${apps[0]}"
        exec -- "${apps[0]}"
    fi
}

# If the script is sourced, don't run main automatically. When executed,
# call main with positional arguments.
if [ "${BASH_SOURCE[0]:-}" = "$0" ]; then
    main "$@"
fi