#!/bin/bash

# Simple interactive menu selector with arrow key support
# No external dependencies, compatible with most bash versions

declare -a menu_options=()
declare -i selected=0
declare -i menu_size=0

# ANSI escape sequences
readonly ESC=$'\033'
readonly UP="${ESC}[A"
readonly DOWN="${ESC}[B"
readonly ENTER=$'\n'
readonly CLEAR_LINE="${ESC}[2K"
readonly HIDE_CURSOR="${ESC}[?25l"
readonly SHOW_CURSOR="${ESC}[?25h"

# Set terminal to raw mode for reading single characters
setup_terminal() {
    # Block until at least 1 byte to avoid false ENTER on empty reads
    stty -echo -icanon min 1 time 0
}

# Restore terminal to normal mode
restore_terminal() {
    stty echo icanon
    printf "%s" "$SHOW_CURSOR"
}

# Draw the menu
draw_menu() {
    local force_full_redraw="${1:-true}"
    printf "%s" "$HIDE_CURSOR"

    if [[ "$force_full_redraw" == "true" ]]; then
        # Full redraw: clear and redraw all lines
        for ((i = 0; i < menu_size; i++)); do
            printf "\r%s" "$CLEAR_LINE"

            if [[ $i -eq $selected ]]; then
                printf "▶ \033[1;32m%s\033[0m\n" "${menu_options[i]}"
            else
                printf "  %s\n" "${menu_options[i]}"
            fi
        done

        # Move cursor back to the beginning and save position
        printf "${ESC}[%dA" $menu_size
        printf "${ESC}7"  # Save cursor position
    else
        # Quick update: only update changed lines
        printf "${ESC}8"  # Restore cursor position

        for ((i = 0; i < menu_size; i++)); do
            printf "\r%s" "$CLEAR_LINE"

            if [[ $i -eq $selected ]]; then
                printf "▶ \033[1;32m%s\033[0m\n" "${menu_options[i]}"
            else
                printf "  %s\n" "${menu_options[i]}"
            fi
        done

        # Move cursor back to the beginning
        printf "${ESC}[%dA" $menu_size
        printf "${ESC}7"  # Save cursor position again
    fi
}

# Read a single key
read_key() {
    local key
    IFS= read -rsn1 key 2>/dev/null || return 1

    case "$key" in
        $'\033')
            local key2 key3
            if IFS= read -rsn1 -t 0.2 key2 2>/dev/null; then
                if [[ "$key2" == "[" ]]; then
                    if IFS= read -rsn1 -t 0.2 key3 2>/dev/null; then
                        case "$key3" in
                            'A') echo "UP" ;;
                            'B') echo "DOWN" ;;
                            'C') echo "RIGHT" ;;
                            'D') echo "LEFT" ;;
                            *) echo "OTHER" ;;
                        esac
                    else
                        echo "OTHER"
                    fi
                else
                    echo "OTHER"
                fi
            else
                echo "OTHER"
            fi
            ;;
        $'\n'|$'\r') echo "ENTER" ;;
        ' ') echo " " ;;
        'q'|'Q') echo "QUIT" ;;
        *) echo "$key" ;;
    esac
}

# Main menu function
# Usage: show_menu "Title" "option1" "option2" "option3" ...
show_menu() {
    local title="$1"
    shift

    # Initialize menu options
    menu_options=("$@")
    menu_size=${#menu_options[@]}
    selected=0

    # Check if we have options
    if [[ $menu_size -eq 0 ]]; then
        echo "Error: No menu options provided" >&2
        return 1
    fi

    # Setup terminal
    setup_terminal
    trap restore_terminal EXIT INT TERM

    # Display title
    if [[ -n "$title" ]]; then
        printf "\n\033[1;34m%s\033[0m\n\n" "$title"
    fi

    # Initial draw
    draw_menu true

    # Main loop
    local first_iteration=true
    while true; do
        local key=$(read_key)

        case "$key" in
            "UP")
                ((selected--))
                if [[ $selected -lt 0 ]]; then
                    selected=$((menu_size - 1))
                fi
                draw_menu false  # Quick update
                ;;
            "DOWN")
                ((selected++))
                if [[ $selected -ge $menu_size ]]; then
                    selected=0
                fi
                draw_menu false  # Quick update
                ;;
            "ENTER")
                # Clear the menu
                for ((i = 0; i < menu_size; i++)); do
                    printf "\r%s\n" "$CLEAR_LINE" >&2
                done
                printf "${ESC}[%dA" $menu_size >&2

                # Show selection
                printf "Selected: \033[1;32m%s\033[0m\n\n" "${menu_options[selected]}"

                restore_terminal
                return $selected
                ;;
            "q"|"Q")
                restore_terminal
                echo "Cancelled." >&2
                return 255
                ;;
            [0-9])
                # Jump to numbered option
                local num=$((key - 1))
                if [[ $num -ge 0 && $num -lt $menu_size ]]; then
                    selected=$num
                    draw_menu
                fi
                ;;
            # Ignore other keys
        esac
    done
}

# Multi-select menu function
# Usage: show_multi_menu "Title" "option1" "option2" "option3" ...
show_multi_menu() {
    local title="$1"
    shift

    # Initialize menu options
    menu_options=("$@")
    menu_size=${#menu_options[@]}
    selected=0

    # Array to track selected items
    declare -a selected_items=()
    for ((i = 0; i < menu_size; i++)); do
        selected_items[i]=false
    done

    # Check if we have options
    if [[ $menu_size -eq 0 ]]; then
        echo "Error: No menu options provided" >&2
        return 1
    fi

    # Setup terminal
    setup_terminal
    trap restore_terminal EXIT INT TERM

    # Display title
    if [[ -n "$title" ]]; then
        printf "\n\033[1;34m%s\033[0m\n" "$title" >&2
        printf "\033[0;36mUse SPACE to select/deselect, ENTER to confirm, Q to quit\033[0m\n\n" >&2
    fi

    # Draw multi-select menu
    draw_multi_menu() {
        local force_full_redraw="${1:-true}"
        printf "%s" "$HIDE_CURSOR" >&2

        if [[ "$force_full_redraw" == "true" ]]; then
            # Full redraw
            for ((i = 0; i < menu_size; i++)); do
                printf "\r%s" "$CLEAR_LINE" >&2

                local checkbox="☐"
                if [[ ${selected_items[i]} == "true" ]]; then
                    checkbox="\033[1;32m☑\033[0m"
                fi

                if [[ $i -eq $selected ]]; then
                    printf "▶ %s \033[1;32m%s\033[0m\n" "$checkbox" "${menu_options[i]}" >&2
                else
                    printf "  %s %s\n" "$checkbox" "${menu_options[i]}" >&2
                fi
            done

            # Move cursor back to the beginning and save position
            printf "${ESC}[%dA" $menu_size >&2
            printf "${ESC}7" >&2  # Save cursor position
        else
            # Quick update
            printf "${ESC}8" >&2  # Restore cursor position

            for ((i = 0; i < menu_size; i++)); do
                printf "\r%s" "$CLEAR_LINE" >&2

                local checkbox="☐"
                if [[ ${selected_items[i]} == "true" ]]; then
                    checkbox="\033[1;32m☑\033[0m"
                fi

                if [[ $i -eq $selected ]]; then
                    printf "▶ %s \033[1;32m%s\033[0m\n" "$checkbox" "${menu_options[i]}" >&2
                else
                    printf "  %s %s\n" "$checkbox" "${menu_options[i]}" >&2
                fi
            done

            # Move cursor back to the beginning and save position
            printf "${ESC}[%dA" $menu_size >&2
            printf "${ESC}7" >&2  # Save cursor position
        fi
    }

    # Initial draw
    draw_multi_menu true

    # Main loop
    while true; do
        local key=$(read_key)

        case "$key" in
            "UP")
                ((selected--))
                if [[ $selected -lt 0 ]]; then
                    selected=$((menu_size - 1))
                fi
                draw_multi_menu false  # Quick update
                ;;
            "DOWN")
                ((selected++))
                if [[ $selected -ge $menu_size ]]; then
                    selected=0
                fi
                draw_multi_menu false  # Quick update
                ;;
            " ")
                # Toggle selection
                if [[ ${selected_items[selected]} == "true" ]]; then
                    selected_items[selected]="false"
                else
                    selected_items[selected]="true"
                fi
                draw_multi_menu false  # Quick update
                ;;
            "ENTER")
                # Clear the menu
                for ((i = 0; i < menu_size; i++)); do
                    printf "\r%s\n" "$CLEAR_LINE" >&2
                done
                printf "${ESC}[%dA" $menu_size >&2

                # Show selections to stderr so it doesn't interfere with return value
                local has_selection=false
                printf "Selected items:\n" >&2
                for ((i = 0; i < menu_size; i++)); do
                    if [[ ${selected_items[i]} == "true" ]]; then
                        printf "  \033[1;32m%s\033[0m\n" "${menu_options[i]}" >&2
                        has_selection=true
                    fi
                done

                if [[ $has_selection == "false" ]]; then
                    printf "  None\n" >&2
                fi
                printf "\n" >&2

                restore_terminal

                # Return selected indices as space-separated string
                local result=""
                for ((i = 0; i < menu_size; i++)); do
                    if [[ ${selected_items[i]} == "true" ]]; then
                        result="$result $i"
                    fi
                done
                echo "${result# }"  # Remove leading space
                return 0
                ;;
            "q"|"Q"|"ESC")
                restore_terminal
                echo "Cancelled." >&2
                return 255
                ;;
        esac
    done
}

# Example usage function
demo_menu() {
    echo "=== Single Select Demo ==="
    if show_menu "Choose an action:" "Install package" "Update system" "Clean cache" "Exit"; then
        local choice=$?
        echo "You selected option $choice"
    fi

    echo -e "\n=== Multi Select Demo ==="
    local selections=$(show_multi_menu "Choose packages to install:" "git" "vim" "curl" "htop" "tree")
    if [[ $? -eq 0 && -n "$selections" ]]; then
        echo "Selected indices: $selections"
        # Convert indices to actual values
        local options=("git" "vim" "curl" "htop" "tree")
        echo "Selected packages:"
        for idx in $selections; do
            echo "  - ${options[idx]}"
        done
    fi
}

# If script is run directly, show demo
if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
    demo_menu
fi