#!/usr/bin/env bash
# =============================================================================
# Script Name : docker-network-manager.sh
# Description : Manage Docker external networks with automatic subnet allocation and tracking.
# Usage:      : ./docker-network-manager.sh <COMMAND> [ARGUMENTS]
#               Commands:
#                 create [NAME] - Create a specific network by name or all networks from file if NO NAME provided.
#                 delete [NAME] - Delete a specific network by name or all networks from file if NO NAME provided.
#                 info          - Show current status and configuration.
#               For details - see README.md
# Author      : syr4ok (Andrii Syrovatko)
# Version     : 1.1.0
# =============================================================================

# --- STRICT MODE ---
set -euo pipefail

# Configuration Loader
CONFIG_FILE="$(dirname "$0")/docker-network-manager.conf"
if [[ -f "$CONFIG_FILE" ]]; then
    # shellcheck source=/dev/null
    source "$CONFIG_FILE"
else
    echo "[Error]: Configuration file not found. Create ip_manager.conf from example."
    exit 1
fi

touch "$NET_FILE"

log() {
  local level="$1"; shift
  printf '%s [%s] %s\n' "$(date -Is)" "$level" "$*" | tee -a "$LOG_FILE"
}

confirm_action() {
  [[ "${FORCE:-false}" == "true" ]] && return 0

  read -rp "Are you sure you want to delete ALL networks from $NET_FILE? (y/N): " response
  case "$response" in
    [yY][eE][sS]|[yY]) return 0 ;;
    *) log INFO "Operation cancelled by user"; exit 0 ;;
  esac
}

# Network check
network_exists() {
  docker network ls --format '{{.Name}}' | grep -Fxq "$1"
}

used_subnets() {
  local escaped_base="${BASE_NET//./\\.}"

  # Get all subnets from existing Docker networks and filter those that match our base pattern
  docker network ls -q | xargs -r docker network inspect 2>/dev/null \
    | grep -oP '"Subnet":\s*"\K'"${escaped_base}"'\.[0-9]+\.0/24' || echo ""
}

next_free_subnet() {
  local used="$1"
  for i in $(seq "$START_OCTET" "$END_OCTET"); do
    local subnet="${BASE_NET}.${i}.0/24"
    if ! grep -q "$subnet" <<<"$used"; then
      echo "$subnet"
      return
    fi
  done
  log ERROR "no free /24 subnet found in ${BASE_NET}.x.x"
  exit 1
}

name_length_check() {
  local name="$1"
  if [[ ${#name} -gt 15 ]]; then
      log WARN "Network name '$name' is too long for a Linux bridge (max 15 chars). It might be truncated."
      return 1
  fi
  return 0
}

provision_single() {
  local name="$1"
  if ! name_length_check "$name"; then
    return 1
  fi
  if network_exists "$name"; then
    log INFO "network already exists name=$name"
    return
  fi

  local used
  local subnet
  used="$(used_subnets)"
  subnet="$(next_free_subnet "$used")"
  local gw="${subnet%0/24}1"

  log INFO "creating network name=$name subnet=$subnet gateway=$gw"
  docker network create --driver bridge --subnet "$subnet" --gateway "$gw" \
    --opt com.docker.network.bridge.name="$name" "$name" >/dev/null

  if ! grep -Fxq "$name" "$NET_FILE"; then
    echo "$name" >> "$NET_FILE"
    log INFO "network name=$name added to $NET_FILE"
    sed -i '/^$/d' "$NET_FILE"
  fi
}

provision_from_file() {
  [[ ! -s "$NET_FILE" ]] && { log WARN "NET_FILE is empty"; return; }
  log INFO "starting mass provisioning from $NET_FILE"
  while read -u 3 -r line; do
    [[ -z "$line" || "$line" =~ ^# ]] && continue
    provision_single "$line" || true
  done 3< "$NET_FILE"
}

delete_network() {
  local name="$1"
  if network_exists "$name"; then
    log INFO "deleting network name=$name"
    docker network rm "$name" >/dev/null
    log INFO "network name=$name deleted from docker"
  else
    log WARN "network not found in docker name=$name — cleanup config anyway"
  fi

  # Remove from NET_FILE if exists
  if grep -Fxq "$name" "$NET_FILE"; then
    sed -i "/^$name$/d" "$NET_FILE"
    log INFO "network name=$name removed from $NET_FILE"
  else
    log INFO "network name=$name not found in $NET_FILE, no cleanup needed"
  fi
}

delete_all_from_file() {
  log INFO "deleting all networks listed in $NET_FILE"
  while read -u 3 -r line; do
    [[ -z "$line" || "$line" =~ ^# ]] && continue
    delete_network "$line"
  done 3< "$NET_FILE"
}

show_info() {
  local tracked_count
  tracked_count=$(grep -cE '^\s*[^#]' "$NET_FILE" || true)

  echo "--- Docker Network Manager v1.1.0 ---"
  echo "Configured Base : ${BASE_NET}.0.0/16 (Range: .${START_OCTET}.x to .${END_OCTET}.x)"
  echo "Config File     : $(basename "$NET_FILE")"
  echo "Log File        : $(basename "$LOG_FILE")"
  echo "Tracked Networks: $tracked_count"

  echo -e "\n[Current Status]"
  if [[ "$tracked_count" -gt 0 ]]; then
    printf "%-20s %-15s %-10s\n" "NETWORK NAME" "IP RANGE" "STATUS"
    echo "--------------------------------------------------------"
    while read -u 3 -r line; do
      [[ -z "$line" || "$line" =~ ^# ]] && continue

      local status="OFFLINE"
      local subnet="N/A"

      if network_exists "$line"; then
        status="ONLINE"
        subnet=$(docker network inspect "$line" --format '{{(index .IPAM.Config 0).Subnet}}' 2>/dev/null || echo "error")
      fi
      printf "%-20s %-15s %-10s\n" "$line" "$subnet" "$status"
    done 3< "$NET_FILE"
  else
    echo "No networks tracked in $NET_FILE"
  fi

  echo -e "\n[Usage]"
  echo "  $0 create (c) [name]  - Create single network and add to file"
  echo "  $0 create (c)         - Create all networks from file"
  echo "  $0 delete (d) [name]  - Remove network and clean file"
  echo "  $0 delete (d)         - Remove all networks from file"
}

case "${1:-info}" in
  [Cc][Rr][Ee][Aa][Tt][Ee]|[Cc])
    if [[ ${2:-} ]]; then
      provision_single "$2"
    else
      provision_from_file
    fi
    ;;
  [Dd][Ee][Ll][Ee][Tt][Ee]|[Dd])
    if [[ ${2:-} ]]; then
      delete_network "$2"
    else
      count=$( (grep -vE '^\s*(#|$)' "$NET_FILE" || true) | wc -l | xargs)

      if (( count == 0 )); then
        log INFO "Nothing to delete. $NET_FILE is empty or contains only comments."
        exit 0
      fi

      confirm_action
      delete_all_from_file
    fi
    ;;
  [Ii][Nn][Ff][Oo]|[Ii])
    show_info
    ;;
  *)
    log ERROR "Unknown command: $1"
    show_info
    exit 1
    ;;
esac

exit 0