#!/bin/bash

# ==============================================================================
# 1. SETTINGS & GLOBALS
# ==============================================================================
# Exit immediately if a command exits with a non-zero status
set -e 

# Determine the directory where this script resides
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
cd "$SCRIPT_DIR"

# Input arguments
client_name="$1"

# Global variables
server_pubkey=""
client_pubkey=""
ips=""

# ==============================================================================
# 2. HELPER FUNCTIONS
# ==============================================================================
# Load environment variable of the script
environment_var() {
    echo "--- Starting Environment & Pre-flight Checks ---"
    # --- .env LOADING ---
    # This safely loads the variables from .env without touching other files
    if [ -f "$SCRIPT_DIR/.env" ]; then
        set -a
        source "$SCRIPT_DIR/.env"
        set +a
        echo "[✔] Environment variables loaded."
    else
        echo "[!] No .env file found. Using defaults."
    fi

    # --- Variable Checks ---
    server_pubkey=$(cat ${WG0_DIR}/publickey)
    ips=$(grep -i '^\s*AllowedIPs\s*=\s*' "${WG0_DIR}/wg0.conf" | sed 's/^\s*AllowedIPs\s*=\s*//I; s/\s*$//')
}

# Find the last registered client IP
find_last_ip() {
    # Find the last ip an create the next ip
    if [ -n "$ips" ]; then
        last=$(printf '%s\n' "$ips" | tail -1)
        addr=${last%/*}   # strip /32 if present
        IFS=. read -r a b c d <<< "$addr"
        next_ip="10.0.0.$((d + 1))"
        printf 'Last CIDR: %s\nNext IP: %s/32\n' "$last" "$next_ip"
    else
        next_ip="10.0.0.2"
        printf 'No peers found, starting at %s/32\n' "$next_ip"
    fi
}

# Remove the client from wg0.conf
client_remove() {
    # Make sure that the client name doesn't have spaces
    if [[ "$client_name" =~ [[:space:]] ]]; then
        printf 'Error: Client name cannot contain spaces. Use underscores instead of spaces.\n'
        exit 1
    elif [[ -z "$client_name" ]]; then
        printf 'Error: Client name argument is mandatory. Please provide one first.\n'
        exit 1
    fi

    # Enforce exact match tags
    local peer_begin="# BEGIN_PEER ${client_name}"
    local peer_end="# END_PEER ${client_name}"

    # Check if peer exists
    if ! grep -q "^${peer_begin}$" "${WG0_DIR}/wg0.conf"; then
        printf 'Error: Peer "%s" not found in wg0.conf\n' "$client_name"
        exit 1
    fi

    # Extract peer info before removal for logging
    peer_block=$(sed -n "/^${peer_begin}$/,/^${peer_end}$/p" "${WG0_DIR}/wg0.conf")
    client_pubkey=$(echo "$peer_block" | grep "PublicKey" | awk '{print $3}')
    client_ip=$(echo "$peer_block" | grep "AllowedIPs" | awk '{print $3}')
    
    # Locate exact block line numbers
    start_line=$(grep -n "^${peer_begin}$" "${WG0_DIR}/wg0.conf" | cut -d: -f1)
    end_line=$(grep -n "^${peer_end}$" "${WG0_DIR}/wg0.conf" | cut -d: -f1)

    # Include the preceding line if it is blank or contains only whitespace
    if [ "$start_line" -gt 1 ]; then
        prev_line=$((start_line - 1))
        if sed -n "${prev_line}p" "${WG0_DIR}/wg0.conf" | grep -q '^[[:space:]]*$'; then
            start_line=$prev_line
        fi
    fi

    # Perform precise line range deletion
    sudo sed -i "${start_line},${end_line}d" "${WG0_DIR}/wg0.conf"
    printf 'Peer "%s" removed from wg0.conf\n' "$client_name"

    # Apply config without restart
    printf 'Applying config to running WireGuard interface...\n'
    if wg syncconf wg0 <(wg-quick strip wg0); then
        printf 'Config applied successfully.\n'
    else
        printf 'Error: wg syncconf failed\n'
        printf 'Check config syntax with: wg-quick strip wg0\n'
        exit 1
    fi

    # Update CSV log: mark client as removed
    csv_file="${TOOLS_DIR}/logs/client_log.csv"
    if [ -f "$csv_file" ]; then
        timestamp=$(date -u +"%Y-%m-%dT%H:%M:%SZ")
        tmp_csv=$(mktemp)
        awk -v cn="$client_name" -v ts="$timestamp" '
            BEGIN { FS=OFS="," }
            NR==1 { print; next }
            $2 == "\"" cn "\"" {
                $1 = ts; $6 = "\"removed\""
            }
            { print }
        ' "$csv_file" > "$tmp_csv" && mv "$tmp_csv" "$csv_file"
        printf 'CSV updated: "%s" marked as removed\n' "$client_name"
    fi

    printf '\n--- Done. The client was removed from WireGuard ---\n'
}

# ==============================================================================
# 3. MAIN LOGIC
# ==============================================================================
main() {
    # Load environment variables first
    environment_var

    # Print current values
    printf 'Public Key of the server: %s\n' "$server_pubkey"
    printf 'List of current clients: %s\n' "$ips"

    # Find the last IP
    find_last_ip
    # Remove the client from wg0.conf
    client_remove
}

# Invoke main
main "$@"