#!/bin/bash
# =============================================================================
# Automated ext4/LUKS disk mounting for macOS using links
# Automates Finder mounting and ensures safe single execution.
#
# Created by: Francesco Galgani
# Website:    https://www.informatica-libera.net/
# License:    CC0 1.0 Universal (Public Domain)
# 
# This script is free of any copyright. Feel free to use it as you wish.
# =============================================================================

set -e

# --- Configuration ---
LOCK_FILE="/tmp/linsk_manager.lock"

# --- Functions ---

# Check if linsk or its VM is already running
check_linsk_running() {
    if pgrep -x "linsk" > /dev/null 2>&1 || pgrep -f "linsk run" > /dev/null 2>&1 || pgrep -f "\.linsk/.*qcow2" > /dev/null 2>&1; then
        echo "[ERROR] An instance of 'linsk' or its virtual machine is already running."
        echo "        Please terminate it (or press Ctrl+C in its terminal) before starting this script."
        exit 1
    fi
}

# Check for existing script instances via lock file
check_single_instance() {
    if [ -e "$LOCK_FILE" ]; then
        local lock_pid
        lock_pid=$(cat "$LOCK_FILE")
        if kill -0 "$lock_pid" 2>/dev/null; then
            echo "[ERROR] Another instance of this script is already running (PID: $lock_pid)."
            echo "        Please finish the current session before starting a new one."
            exit 1
        else
            echo "[WARN] Found stale lock file. Removing it..."
            rm -f "$LOCK_FILE"
        fi
    fi
    echo $$ > "$LOCK_FILE"
}

# Find Linux partition
find_linux_partition() {
    echo "[INFO] Searching for Linux partitions on external disks..."
    local partitions=()
    
    # Get list of external physical disks identifiers (e.g., disk3, disk4)
    local disks=$(diskutil list | grep "external, physical" | awk -F':' '{print $1}' | awk '{print $1}')
    
    if [ -z "$disks" ]; then
        echo "[ERROR] No external physical disks found. Please connect your disk."
        rm -f "$LOCK_FILE"
        exit 1
    fi

    for disk in $disks; do
        # Extract partition identifier for Linux type
        local parts=$(diskutil list "$disk" | grep "Linux" | awk '{print $NF}')
        for part in $parts; do
            # Clean up any invisible characters/spaces
            part=$(echo "$part" | tr -d '[:space:]')
            if [ -n "$part" ]; then
                partitions+=("/dev/$part")
            fi
        done
    done

    if [ ${#partitions[@]} -eq 0 ]; then
        echo "[ERROR] No Linux partitions found on external disks."
        echo "        Note: This script does not currently support LVM (Logical Volume Manager)."
        echo "        Please check your disk manually following the instructions at:"
        echo "        https://github.com/AlexSSD7/linsk/blob/master/USAGE_MACOS.md"
        rm -f "$LOCK_FILE"
        exit 1
    elif [ ${#partitions[@]} -eq 1 ]; then
        SELECTED_PARTITION="${partitions[0]}"
        echo "[INFO] Automatically selected partition: $SELECTED_PARTITION"
    else
        echo "[INFO] Multiple Linux partitions found:"
        for i in "${!partitions[@]}"; do
            echo "  $((i+1)). ${partitions[$i]}"
        done
        read -p "Select partition number (1-${#partitions[@]}): " sel
        if [[ "$sel" =~ ^[0-9]+$ ]] && [ "$sel" -ge 1 ] && [ "$sel" -le "${#partitions[@]}" ]; then
            SELECTED_PARTITION="${partitions[$((sel-1))]}"
            echo "[INFO] Selected partition: $SELECTED_PARTITION"
        else
            echo "[ERROR] Invalid selection."
            rm -f "$LOCK_FILE"
            exit 1
        fi
    fi
    
    # Final cleanup of the variable to prevent stat errors in linsk
    SELECTED_PARTITION=$(echo "$SELECTED_PARTITION" | tr -d '[:space:]')
}

# Auto-detect LUKS by reading the partition header
detect_luks() {
    echo "[INFO] Checking partition type (LUKS vs standard)..."
    # LUKS headers start with the magic bytes 4c 55 4b 53 ba be (which spells "LUKS\xba\xbe")
    # We read the first 6 bytes and convert them to hex to avoid grep binary issues.
    local hex_header
    hex_header=$(sudo dd if="$SELECTED_PARTITION" bs=6 count=1 2>/dev/null | hexdump -ve '6/1 "%02x"')
    
    if [[ "$hex_header" == "4c554b53babe" ]]; then
        LUKS_FLAG="-l"
        echo "[INFO] LUKS encryption detected automatically."
        echo ">>> NOTE: When the terminal prompts 'Enter Password:', enter your LUKS decryption password."
    else
        LUKS_FLAG=""
        echo "[INFO] Standard Linux filesystem detected (non-LUKS). No password will be required."
    fi
}

# Cleanup on exit
cleanup() {
    echo ""
    echo "[INFO] Script interrupted. Cleaning up..."
    
    if [ -n "$MONITOR_PID" ]; then
        kill "$MONITOR_PID" 2>/dev/null
    fi
    
    # Clean temp file and lock file
    rm -f "$TMP_LOG"
    rm -f "$LOCK_FILE"
    
    echo "[INFO] Done. You can safely disconnect your disk."
    exit 0
}

# --- Main Execution ---

if [ "$EUID" -ne 0 ]; then
    echo "Please run this script with sudo: sudo $0"
    exit 1
fi

# Check if linsk is installed
if ! command -v linsk > /dev/null 2>&1; then
    echo "[ERROR] 'linsk' command not found."
    echo "        Please install it following the instructions at:"
    echo "        https://github.com/AlexSSD7/linsk/blob/master/INSTALL_MACOS.md"
    exit 1
fi

echo "============================================================"
echo "linsk source code and documentation: https://github.com/AlexSSD7/linsk"
echo "Script created by Francesco Galgani: https://www.informatica-libera.net"
echo "============================================================"
echo ">>> DISCLAIMER: This script does not support LVM volumes."
echo "    If macOS shows the 'disk not readable' popup, click 'Ignore'."
echo "============================================================"
echo ""

check_linsk_running
check_single_instance

TMP_LOG=$(mktemp)
trap cleanup SIGINT SIGTERM

# 1. Find the Linux partition (disk must already be connected)
find_linux_partition

# Verify the device node actually exists in /dev before proceeding
if [ ! -e "$SELECTED_PARTITION" ]; then
    echo "[ERROR] Device $SELECTED_PARTITION does not exist!"
    echo "        This can happen if macOS failed to register the device node."
    echo "        Try unplugging and replugging the disk, then run the script again."
    rm -f "$LOCK_FILE"
    exit 1
fi

# 2. Auto-detect if it's LUKS encrypted
detect_luks

echo ""
echo "[INFO] Starting linsk..."
echo "============================================================"
echo ">>> IMPORTANT: When you are finished using the disk:"
echo "1. Eject the 'linsk' network drive in Finder (Right-click -> Eject)"
echo "2. Then return to this terminal and press Ctrl+C to exit."
echo "============================================================"
echo ""

# Background process to monitor log and auto-mount share in Finder
(
    tail -f -n +1 "$TMP_LOG" | while read -r line; do
        # Look for the AFP password line (e.g., "Password: 5J076gRa2493AG18")
        if [[ "$line" == "Password:"* ]]; then
            AFP_PASS=$(echo "$line" | awk '{print $2}')
            if [ -n "$AFP_PASS" ]; then
                echo ""
                echo "[INFO] AFP Share credentials detected, you may need to enter manually the password: ${AFP_PASS}. Mounting automatically in Finder..."
                
                # Get the UID of the original user who invoked sudo
                ORIGINAL_UID=$(id -u "$SUDO_USER")

                # 'open' mounts the AFP volume via Finder
                launchctl asuser "$ORIGINAL_UID" sudo -u "$SUDO_USER" open "afp://linsk:${AFP_PASS}@127.0.0.1:9000/linsk"
                echo ""
                echo ""
                echo "[INFO] Finder window should open shortly."
                # Stop monitoring once mounted
                break
            fi
        fi
    done
) &
MONITOR_PID=$!

# Run linsk in foreground with PTY to allow interactive password input (if LUKS)
# 'script' provides the PTY, 'tee' writes to the terminal and the log file in real-time.
script -q /dev/null linsk run $LUKS_FLAG "dev:$SELECTED_PARTITION" 2>&1 | tee "$TMP_LOG"

# If script exits naturally, cleanup
cleanup