# =============================================================================
# MySQL Slave StatefulSet for Gition
# - 2 replicas for read scaling
# - Auto-configure replication from Master (172.100.100.11)
# =============================================================================

# =============================================================================
# 1. ConfigMap - MySQL Slave 설정
# =============================================================================
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: mysql-slave-config
  namespace: gition
data:
  my.cnf: |
    [mysqld]
    server-id = 2
    gtid_mode = ON
    enforce_gtid_consistency = ON
    read_only = ON
    log_bin = mysql-bin
    binlog_format = ROW
    skip_host_cache
    skip_name_resolve

  # Replication 설정 스크립트
  setup-replication.sh: |
    #!/bin/bash
    set -e

    # MySQL이 준비될 때까지 대기
    echo "[Replication Setup] Waiting for MySQL to be ready..."
    until mysql -uroot -p"$MYSQL_ROOT_PASSWORD" -e "SELECT 1" &>/dev/null; do
      echo "[Replication Setup] MySQL not ready, waiting..."
      sleep 5
    done
    echo "[Replication Setup] MySQL is ready!"

    # pista 사용자 인증 방식 변경 (caching_sha2_password → mysql_native_password)
    echo "[Replication Setup] Configuring pista user with mysql_native_password..."
    mysql -uroot -p"$MYSQL_ROOT_PASSWORD" -e "
      ALTER USER 'pista'@'%' IDENTIFIED WITH mysql_native_password BY '${MYSQL_USER_PASSWORD}';
      GRANT ALL PRIVILEGES ON gition.* TO 'pista'@'%';
      FLUSH PRIVILEGES;
    " 2>/dev/null || echo "[Replication Setup] pista user config skipped (may already exist)"

    # 초기 스키마 동기화 (테이블이 없으면 Master에서 복사)
    TABLE_COUNT=$(mysql -uroot -p"$MYSQL_ROOT_PASSWORD" -N -e "SELECT COUNT(*) FROM information_schema.tables WHERE table_schema='gition';" 2>/dev/null || echo "0")
    if [ "$TABLE_COUNT" -eq 0 ] || [ "$TABLE_COUNT" = "0" ]; then
      echo "[Replication Setup] No tables found. Importing schema from Master..."
      mysqldump -h "${MYSQL_MASTER_HOST}" -uroot -p"${MYSQL_ROOT_PASSWORD}" \
        --single-transaction --set-gtid-purged=OFF gition 2>/dev/null | \
        mysql -uroot -p"$MYSQL_ROOT_PASSWORD" gition
      echo "[Replication Setup] Schema import completed!"
    else
      echo "[Replication Setup] Tables already exist ($TABLE_COUNT tables). Skipping schema import."
    fi

    # 이미 복제가 설정되어 있는지 확인
    REPLICA_STATUS=$(mysql -uroot -p"$MYSQL_ROOT_PASSWORD" -N -e "SHOW REPLICA STATUS\G" 2>/dev/null || true)
    if echo "$REPLICA_STATUS" | grep -q "Replica_IO_Running: Yes"; then
      echo "[Replication Setup] Replication already running. Skipping setup."
      exit 0
    fi

    echo "[Replication Setup] Configuring replication to Master..."

    # 복제 중지 및 리셋 (기존 설정이 있을 경우)
    mysql -uroot -p"$MYSQL_ROOT_PASSWORD" -e "STOP REPLICA; RESET REPLICA ALL;" 2>/dev/null || true

    # 복제 설정
    mysql -uroot -p"$MYSQL_ROOT_PASSWORD" <<EOF
    CHANGE REPLICATION SOURCE TO
      SOURCE_HOST='${MYSQL_MASTER_HOST}',
      SOURCE_PORT=3306,
      SOURCE_USER='${REPL_USER}',
      SOURCE_PASSWORD='${REPL_PASSWORD}',
      SOURCE_AUTO_POSITION=1,
      GET_SOURCE_PUBLIC_KEY=1;
    EOF

    # 복제 시작
    mysql -uroot -p"$MYSQL_ROOT_PASSWORD" -e "START REPLICA;"

    # 결과 확인
    sleep 3
    echo "[Replication Setup] Checking replication status..."
    mysql -uroot -p"$MYSQL_ROOT_PASSWORD" -e "SHOW REPLICA STATUS\G" | grep -E "Replica_IO_Running|Replica_SQL_Running|Last_Error"

    echo "[Replication Setup] Done!"


# =============================================================================
# 2. StatefulSet - MySQL Slave Pods
# =============================================================================
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: mysql-slave
  namespace: gition
spec:
  serviceName: mysql-read
  replicas: 2
  selector:
    matchLabels:
      app: mysql
      role: slave
  template:
    metadata:
      labels:
        app: mysql
        role: slave
    spec:
      # InitContainer - Pod별 server-id 동적 생성 (mysql-slave-0→100, mysql-slave-1→101)
      initContainers:
      - name: init-mysql
        image: mysql:8.0
        command:
        - bash
        - "-c"
        - |
          # Pod 인덱스에 따라 server-id 설정
          [[ $HOSTNAME =~ -([0-9]+)$ ]] || exit 1
          ordinal=${BASH_REMATCH[1]}
          echo "[mysqld]" > /mnt/conf.d/server-id.cnf
          echo "server-id=$((100 + $ordinal))" >> /mnt/conf.d/server-id.cnf
          echo "[Init] Set server-id=$((100 + $ordinal)) for $HOSTNAME"
        volumeMounts:
        - name: conf
          mountPath: /mnt/conf.d

      containers:
      # Main MySQL Container
      - name: mysql
        image: mysql:8.0
        env:
        - name: MYSQL_ROOT_PASSWORD
          valueFrom:
            secretKeyRef:
              name: mysql-secret
              key: root-password
        - name: MYSQL_DATABASE
          value: gition
        - name: MYSQL_USER
          value: pista
        - name: MYSQL_PASSWORD
          valueFrom:
            secretKeyRef:
              name: mysql-secret
              key: user-password
        ports:
        - name: mysql
          containerPort: 3306
        volumeMounts:
        - name: data
          mountPath: /var/lib/mysql
        - name: conf
          mountPath: /etc/mysql/conf.d
        - name: config-map
          mountPath: /etc/mysql/conf.d/slave.cnf
          subPath: my.cnf
        resources:
          requests:
            cpu: 250m
            memory: 512Mi
          limits:
            cpu: 1000m
            memory: 2Gi
        livenessProbe:
          exec:
            command:
            - bash
            - -c
            - mysqladmin ping -uroot -p"$MYSQL_ROOT_PASSWORD"
          initialDelaySeconds: 30
          periodSeconds: 10
        readinessProbe:
          exec:
            command:
            - bash
            - -c
            - mysql -uroot -p"$MYSQL_ROOT_PASSWORD" -e "SELECT 1"
          initialDelaySeconds: 5
          periodSeconds: 5

      # Sidecar - 복제 설정 자동화 (한 번 실행 후 sleep)
      - name: replication-setup
        image: mysql:8.0
        command:
        - bash
        - -c
        - |
          # 스크립트 복사 및 실행
          cp /scripts/setup-replication.sh /tmp/setup-replication.sh
          chmod +x /tmp/setup-replication.sh
          /tmp/setup-replication.sh
          # 설정 완료 후 대기 (컨테이너 유지)
          echo "[Replication Setup] Sleeping forever..."
          sleep infinity
        env:
        - name: MYSQL_ROOT_PASSWORD
          valueFrom:
            secretKeyRef:
              name: mysql-secret
              key: root-password
        - name: MYSQL_MASTER_HOST
          value: "172.100.100.11"
        - name: REPL_USER
          value: "repl_pista"
        - name: REPL_PASSWORD
          valueFrom:
            secretKeyRef:
              name: mysql-secret
              key: repl-password
        - name: MYSQL_USER_PASSWORD
          valueFrom:
            secretKeyRef:
              name: mysql-secret
              key: user-password
        volumeMounts:
        - name: config-map
          mountPath: /scripts
        resources:
          requests:
            cpu: 10m
            memory: 32Mi
          limits:
            cpu: 100m
            memory: 64Mi

      volumes:
      - name: conf
        emptyDir: {}
      - name: config-map
        configMap:
          name: mysql-slave-config
          defaultMode: 0755

  volumeClaimTemplates:
  - metadata:
      name: data
    spec:
      accessModes: ["ReadWriteOnce"]
      storageClassName: nfs-client
      resources:
        requests:
          storage: 10Gi


# =============================================================================
# 3. Service - MySQL Read (Headless for StatefulSet)
# =============================================================================
---
apiVersion: v1
kind: Service
metadata:
  name: mysql-read
  namespace: gition
spec:
  selector:
    app: mysql
    role: slave
  ports:
  - port: 3306
    targetPort: 3306