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

# 创建大日志主 Topic 及独立 Retry/DLT/Replay Topic。不删除消息、不修改消费组 offset。
BOOTSTRAP="${BOOTSTRAP:-10.141.121.35:9092,10.141.121.50:9092,10.141.121.59:9092}"
RAW_TOPIC="${RAW_TOPIC:-agent-01-syslog-topic}"
LARGE_TOPIC="${LARGE_TOPIC:-${RAW_TOPIC}.large}"
MAX_MESSAGE_BYTES="${MAX_MESSAGE_BYTES:-33554432}"
RETENTION_MS="${RETENTION_MS:-604800000}"
DLT_RETENTION_MS="${DLT_RETENTION_MS:-2592000000}"

if [[ -z "${KAFKA_BIN:-}" ]]; then
  for candidate in \
    "$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)" \
    "/opt/kafka/kafka_2.13-3.6.1/bin" \
    "/opt/kafka/bin" \
    "/usr/local/kafka/bin"; do
    if [[ -x "${candidate}/kafka-topics.sh" ]] && [[ -x "${candidate}/kafka-configs.sh" ]]; then
      KAFKA_BIN="${candidate}"
      break
    fi
  done
fi
if [[ -z "${KAFKA_BIN:-}" ]] && command -v kafka-topics.sh >/dev/null 2>&1; then
  KAFKA_BIN=$(dirname -- "$(command -v kafka-topics.sh)")
fi
if [[ -z "${KAFKA_BIN:-}" ]]; then
  echo "ERROR: 未找到 Kafka CLI；请设置 KAFKA_BIN" >&2
  exit 1
fi

TOPICS="${KAFKA_BIN}/kafka-topics.sh"
CONFIGS="${KAFKA_BIN}/kafka-configs.sh"
COMMON=(--bootstrap-server "${BOOTSTRAP}")
if [[ -n "${COMMAND_CONFIG:-}" ]]; then
  [[ -r "${COMMAND_CONFIG}" ]] || { echo "ERROR: 无法读取 ${COMMAND_CONFIG}" >&2; exit 1; }
  COMMON+=(--command-config "${COMMAND_CONFIG}")
fi

RAW_INFO=$("${TOPICS}" "${COMMON[@]}" --describe --topic "${RAW_TOPIC}")
PARTITIONS=$(printf '%s\n' "${RAW_INFO}" | awk '
  /PartitionCount:/ {for(i=1;i<=NF;i++) if($i=="PartitionCount:"){print $(i+1);exit}}
')
REPLICAS=$(printf '%s\n' "${RAW_INFO}" | awk '
  /ReplicationFactor:/ {for(i=1;i<=NF;i++) if($i=="ReplicationFactor:"){print $(i+1);exit}}
')
if [[ ! "${PARTITIONS}" =~ ^[1-9][0-9]*$ ]] || [[ ! "${REPLICAS}" =~ ^[1-9][0-9]*$ ]]; then
  echo "ERROR: 无法读取 ${RAW_TOPIC} 的分区数或副本数" >&2
  exit 1
fi

declare -a TOPIC_NAMES=(
  "${LARGE_TOPIC}"
  "${LARGE_TOPIC}.RETRY.1M"
  "${LARGE_TOPIC}.RETRY.10M"
  "${LARGE_TOPIC}.RETRY.1H"
  "${LARGE_TOPIC}.DLT"
  "${LARGE_TOPIC}.REPLAY"
)

echo "Kafka=${BOOTSTRAP}，分区=${PARTITIONS}，副本=${REPLICAS}，单条上限=${MAX_MESSAGE_BYTES}"
for topic in "${TOPIC_NAMES[@]}"; do
  topic_retention="${RETENTION_MS}"
  [[ "${topic}" == "${LARGE_TOPIC}.DLT" ]] && topic_retention="${DLT_RETENTION_MS}"
  "${TOPICS}" "${COMMON[@]}" --create --if-not-exists \
    --topic "${topic}" --partitions "${PARTITIONS}" --replication-factor "${REPLICAS}" \
    --config cleanup.policy=delete \
    --config "retention.ms=${topic_retention}" \
    --config "max.message.bytes=${MAX_MESSAGE_BYTES}"
  "${CONFIGS}" "${COMMON[@]}" --alter --entity-type topics --entity-name "${topic}" \
    --add-config "cleanup.policy=delete,retention.ms=${topic_retention},max.message.bytes=${MAX_MESSAGE_BYTES}"
  "${TOPICS}" "${COMMON[@]}" --describe --topic "${topic}"
done

echo "PASS: 大日志 Topic 已创建并统一配置。"
echo "注意：Broker 的 replica.fetch.max.bytes 也必须不小于 ${MAX_MESSAGE_BYTES}。"
echo "脚本未删除消息，也未修改任何消费组 offset。"