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

if [[ $# -lt 4 ]]; then
  echo "Usage: $0 <stack-name> <service-name> <stack-file> <health-url> [expected-replicas]" >&2
  exit 1
fi

STACK_NAME="$1"
SERVICE_NAME="$2"
STACK_FILE="$3"
HEALTH_URL="$4"
EXPECTED_REPLICAS="${5:-4}"

SERVICE_FQDN="${STACK_NAME}_${SERVICE_NAME}"
LOG_PREFIX="[swarm-deploy]"

log() {
  printf '%s %s %s\n' "$(date --iso-8601=seconds)" "$LOG_PREFIX" "$*"
}

retry() {
  local attempts=$1; shift
  local delay=$1; shift
  local n=1
  while true; do
    if "$@"; then
      return 0
    fi
    if (( n == attempts )); then
      return 1
    fi
    ((n++))
    sleep "$delay"
  done
}

log "Deploying stack '${STACK_NAME}' using ${STACK_FILE}"
docker stack deploy --compose-file "$STACK_FILE" "$STACK_NAME"

log "Waiting for service ${SERVICE_FQDN} to reach ${EXPECTED_REPLICAS} replicas"
retries=24
while (( retries > 0 )); do
  replicas_raw=$(docker service ls --filter "name=${SERVICE_FQDN}" --format '{{.Replicas}}' || true)
  if [[ -z "$replicas_raw" ]]; then
    log "Service ${SERVICE_FQDN} not found yet; retrying"
    sleep 5
    ((retries--))
    continue
  fi
  replicas_clean=${replicas_raw%% (*}
  running=${replicas_clean%%/*}
  desired=${replicas_clean##*/}
  if [[ "$running" == "$desired" && "$running" == "$EXPECTED_REPLICAS" ]]; then
    log "Service reached desired replica count: ${running}/${desired}"
    break
  fi
  log "Current replicas ${running}/${desired}; waiting..."
  sleep 5
  ((retries--))
done

if (( retries == 0 )); then
  log "Timed out waiting for replicas"
  docker service ps "$SERVICE_FQDN"
  exit 1
fi

log "Checking task states"
if ! docker service ps "$SERVICE_FQDN" --no-trunc --filter 'desired-state=Running' --format '{{.CurrentState}}' | grep -q '^Running '; then
  log "Some tasks are not running"
  docker service ps "$SERVICE_FQDN"
  exit 1
fi

log "Running health check against ${HEALTH_URL}"
if ! retry 3 5 curl -fsS "$HEALTH_URL"; then
  log "Health check failed; rolling back service"
  docker service update --rollback "$SERVICE_FQDN" || true
  exit 1
fi

log "Health check succeeded"
log "Deployment finished successfully"