#!/usr/bin/env bash
set -euo pipefail

CONF_FILE=/etc/evobgp/firewall.conf
LOG_FILE=/var/log/evobgp-firewall.log
STATE_DIR=/var/lib/evobgp-firewall
HASH_FILE="${STATE_DIR}/last_hash"

log() { echo "$(date -u +%Y-%m-%dT%H:%M:%SZ) $*" | tee -a "$LOG_FILE"; }

if [[ ! -f "$CONF_FILE" ]]; then
  log "missing $CONF_FILE"
  exit 1
fi
# shellcheck disable=SC1090
source "$CONF_FILE"

: "${EVOBGP_CP_URL:?}"
: "${CLIENT_TOKEN:?}"

mkdir -p "$STATE_DIR"
BACKEND="${KERNEL_BACKEND:-auto}"

curl_get_blocklist() {
  local url="$1"
  local host
  host=$(echo "$url" | sed -E 's#https?://([^/]+)/?.*#\1#')
  local tmp
  tmp=$(mktemp)
  local code
  code=$(curl -sS -o "$tmp" -w "%{http_code}" \
    -H "Authorization: Bearer ${CLIENT_TOKEN}" \
    -H "Accept: application/json" \
    "${url}/v1/firewall/blocklist") || return 1
  if [[ "$code" == "403" ]]; then
    log "pending approval"
    rm -f "$tmp"
    exit 0
  fi
  if [[ "$code" != "200" ]]; then
    log "blocklist HTTP $code from $url"
    rm -f "$tmp"
    return 1
  fi
  cat "$tmp"
  rm -f "$tmp"
}

try_urls() {
  local urls=()
  if [[ -n "${EVOBGP_FAILOVER_URLS:-}" ]]; then
    IFS=',' read -r -a urls <<<"$EVOBGP_FAILOVER_URLS"
  else
    urls=("${EVOBGP_CP_URL%/}")
  fi
  local u
  for u in "${urls[@]}"; do
    u="${u// /}"
    u="${u%/}"
    if OUT=$(curl_get_blocklist "$u"); then
      CP_HIT="$u"
      return 0
    fi
  done
  return 1
}

if ! OUT=$(try_urls); then
  log "all endpoints failed"
  exit 1
fi

if command -v jq >/dev/null 2>&1; then
  HASH=$(echo "$OUT" | jq -r '.hash // empty')
  TOTAL=$(echo "$OUT" | jq -r '.total // 0')
  mapfile -t PREFIXES < <(echo "$OUT" | jq -r '.prefixes[]?')
else
  HASH=$(echo "$OUT" | grep -o '"hash"[[:space:]]*:[[:space:]]*"[^"]*"' | head -1 | sed 's/.*"\(sha256:[^"]*\)".*/\1/')
  TOTAL=$(echo "$OUT" | grep -o '"total"[[:space:]]*:[[:space:]]*[0-9]*' | head -1 | grep -o '[0-9]*$')
  mapfile -t PREFIXES < <(echo "$OUT" | grep -o '"[0-9a-fA-F:.]*/[0-9]*"' | tr -d '"')
fi

if [[ -f "$HASH_FILE" && "$(cat "$HASH_FILE")" == "$HASH" ]]; then
  log "unchanged hash $HASH — skip kernel apply"
  exit 0
fi

apply_nft() {
  local table=inet
  local name=evobgp_blocklist
  nft list table "$table" "$name" >/dev/null 2>&1 || nft add table "$table" "$name"
  nft list set "$table" "$name" v4 >/dev/null 2>&1 || nft add set "$table" "$name" v4 '{ type ipv4_addr; flags interval; }'
  nft flush set "$table" "$name" v4
  if ((${#PREFIXES[@]})); then
    local v4=()
    local p
    for p in "${PREFIXES[@]}"; do
      [[ "$p" == *:* ]] && continue
      v4+=("$p")
    done
    if ((${#v4[@]})); then
      nft add element "$table" "$name" v4 "{ $(IFS=,; echo "${v4[*]}") }"
    fi
  fi
  nft list chain "$table" "$name" input >/dev/null 2>&1 || {
    nft add chain "$table" "$name" input '{ type filter hook input priority 0; }'
    nft add rule "$table" "$name" input ip saddr @v4 drop
  }
}

apply_ipset() {
  local set=evobgp_blocklist_v4
  ipset list "$set" >/dev/null 2>&1 || ipset create "$set" hash:net family inet hashsize 4096 maxelem 1048576
  ipset flush "$set"
  local p
  for p in "${PREFIXES[@]}"; do
    [[ "$p" == *:* ]] && continue
    ipset add "$set" "$p" -exist
  done
  iptables -C INPUT -m set --match-set "$set" src -j DROP 2>/dev/null || \
    iptables -I INPUT -m set --match-set "$set" src -j DROP
}

apply_iptables_only() {
  iptables -D INPUT -m comment --comment evobgp-block -j DROP 2>/dev/null || true
  if ((${#PREFIXES[@]})); then
    local p
    for p in "${PREFIXES[@]}"; do
      [[ "$p" == *:* ]] && continue
      iptables -C INPUT -s "$p" -j DROP 2>/dev/null || iptables -A INPUT -s "$p" -j DROP
    done
  fi
}

clear_block() {
  case "$BACKEND" in
    nft) nft delete table inet evobgp_blocklist 2>/dev/null || true ;;
    ipset)
      ipset destroy evobgp_blocklist_v4 2>/dev/null || true
      iptables -D INPUT -m set --match-set evobgp_blocklist_v4 src -j DROP 2>/dev/null || true
      ;;
    iptables) iptables -S INPUT | grep -i evobgp | sed 's/^-A /-D /' | while read -r line; do iptables $line 2>/dev/null || true; done ;;
  esac
}

if [[ "$TOTAL" == "0" || ${#PREFIXES[@]} -eq 0 ]]; then
  clear_block
else
  case "$BACKEND" in
    nft|auto) if command -v nft >/dev/null 2>&1; then apply_nft; else apply_ipset; fi ;;
    ipset) apply_ipset ;;
    iptables) apply_iptables_only ;;
    *) apply_ipset ;;
  esac
fi

echo "$HASH" >"$HASH_FILE"
log "applied $TOTAL prefixes from ${CP_HIT:-$EVOBGP_CP_URL} backend=$BACKEND"

REPORT=$(printf '{"status":"ok","prefix_count":%s,"ip_count":0,"source":"cp"}' "${TOTAL:-0}")
curl -fsS -X POST "${EVOBGP_CP_URL%/}/v1/firewall/apply-report" \
  -H "Authorization: Bearer ${CLIENT_TOKEN}" \
  -H "Content-Type: application/json" \
  -d "$REPORT" >/dev/null 2>&1 || true

curl -fsS -X POST "${EVOBGP_CP_URL%/}/v1/firewall/heartbeat" \
  -H "Authorization: Bearer ${CLIENT_TOKEN}" \
  -H "Content-Type: application/json" \
  -d '{"source":"cp"}' >/dev/null 2>&1 || true