#!/bin/bash
# ============================================================
# 数据库备份脚本
# 
# 功能:
#   - PostgreSQL 全量备份 (pg_dump)
#   - 备份保留策略: 每日(7天) + 每周(4周) + 每月(12月)
#   - 压缩 + 可选加密
#   - 上传到 MinIO/S3 或本地归档
#   - 企业微信通知备份结果
#
# Cron 配置 (每天凌晨 2 点执行):
#   0 2 * * * /opt/water-management/deploy/production/backup/backup-db.sh >> /var/log/wm-backup.log 2>&1
# ============================================================
set -euo pipefail

# ==================== 配置 ====================
# 数据库配置
DB_HOST="${DB_HOST:-localhost}"
DB_PORT="${DB_PORT:-5432}"
DB_NAME="${POSTGRES_DB:-water_management}"
DB_USER="${POSTGRES_USER:-water}"
DB_PASSWORD="${POSTGRES_PASSWORD:-}"
PGPASSWORD="${DB_PASSWORD}"
export PGPASSWORD

# 备份目录
BACKUP_BASE="${BACKUP_DIR:-/opt/water-management/backups}"
BACKUP_DAILY="${BACKUP_BASE}/daily"
BACKUP_WEEKLY="${BACKUP_BASE}/weekly"
BACKUP_MONTHLY="${BACKUP_BASE}/monthly"

# 保留策略
DAILY_RETENTION=7
WEEKLY_RETENTION=4
MONTHLY_RETENTION=12

# MinIO/S3 配置（可选）
S3_ENABLED="${S3_ENABLED:-false}"
S3_BUCKET="${S3_BUCKET:-water-backups}"
S3_ENDPOINT="${S3_ENDPOINT:-http://localhost:9000}"
S3_ACCESS_KEY="${S3_ACCESS_KEY:-}"
S3_SECRET_KEY="${S3_SECRET_KEY:-}"

# 加密配置（可选）
ENCRYPT_ENABLED="${ENCRYPT_ENABLED:-false}"
ENCRYPT_PASSPHRASE="${ENCRYPT_PASSPHRASE:-}"

# 企业微信 Webhook
WECOM_WEBHOOK="${WECOM_WEBHOOK:-}"

# ==================== 初始化 ====================
TIMESTAMP=$(date +%Y%m%d_%H%M%S)
DATE=$(date +%Y-%m-%d)
DAY_OF_WEEK=$(date +%u)  # 1=Monday, 7=Sunday
DAY_OF_MONTH=$(date +%d)

log() {
    echo "[$(date '+%Y-%m-%d %H:%M:%S')] $1"
}

# 创建备份目录
mkdir -p "$BACKUP_DAILY" "$BACKUP_WEEKLY" "$BACKUP_MONTHLY"

# ==================== 备份函数 ====================

# 全量备份
do_full_backup() {
    local target_dir="$1"
    local backup_name="wm_${DB_NAME}_${TIMESTAMP}.sql.gz"
    local backup_path="${target_dir}/${backup_name}"
    
    log "📦 开始全量备份: ${DB_NAME}"
    
    # pg_dump 全量备份 + gzip 压缩
    pg_dump \
        -h "$DB_HOST" \
        -p "$DB_PORT" \
        -U "$DB_USER" \
        -d "$DB_NAME" \
        --format=plain \
        --verbose \
        --no-owner \
        --no-privileges \
        --clean \
        --if-exists \
        2>/dev/null | gzip -9 > "$backup_path"
    
    local size
    size=$(du -sh "$backup_path" | cut -f1)
    log "✅ 备份完成: ${backup_name} (${size})"
    
    # 可选加密
    if [ "$ENCRYPT_ENABLED" = "true" ] && [ -n "$ENCRYPT_PASSPHRASE" ]; then
        log "🔐 加密备份文件..."
        openssl enc -aes-256-cbc -salt -pbkdf2 \
            -in "$backup_path" \
            -out "${backup_path}.enc" \
            -pass "pass:${ENCRYPT_PASSPHRASE}"
        rm "$backup_path"
        backup_path="${backup_path}.enc"
        log "✅ 加密完成"
    fi
    
    # 上传到 S3/MinIO
    if [ "$S3_ENABLED" = "true" ]; then
        upload_to_s3 "$backup_path"
    fi
    
    echo "$backup_path"
}

# 上传到 S3/MinIO
upload_to_s3() {
    local file="$1"
    local filename
    filename=$(basename "$file")
    local s3_path="s3://${S3_BUCKET}/db/${DATE}/${filename}"
    
    log "☁️ 上传到 S3: ${s3_path}"
    
    # 使用 mc (MinIO Client) 或 aws cli
    if command -v mc &>/dev/null; then
        mc alias set wm-s3 "$S3_ENDPOINT" "$S3_ACCESS_KEY" "$S3_SECRET_KEY" 2>/dev/null
        mc cp "$file" "wm-s3/${S3_BUCKET}/db/${DATE}/${filename}" 2>/dev/null
    elif command -v aws &>/dev/null; then
        aws --endpoint-url "$S3_ENDPOINT" s3 cp "$file" "$s3_path" 2>/dev/null
    else
        log "⚠️ 未找到 mc 或 aws 命令，跳过 S3 上传"
        return 0
    fi
    
    log "✅ S3 上传完成"
}

# ==================== 保留策略 ====================

# 清理过期备份
cleanup_old_backups() {
    log "🧹 执行备份保留策略..."
    
    # 每日备份：保留最近 N 天
    local daily_count
    daily_count=$(ls -1 "$BACKUP_DAILY"/*.sql.gz 2>/dev/null | wc -l || echo 0)
    if [ "$daily_count" -gt "$DAILY_RETENTION" ]; then
        local to_delete=$((daily_count - DAILY_RETENTION))
        log "  清理每日备份: 删除最旧的 ${to_delete} 个文件"
        ls -1t "$BACKUP_DAILY"/*.sql.gz 2>/dev/null | tail -n "$to_delete" | xargs rm -f
    fi
    
    # 每周备份：保留最近 N 周
    local weekly_count
    weekly_count=$(ls -1 "$BACKUP_WEEKLY"/*.sql.gz 2>/dev/null | wc -l || echo 0)
    if [ "$weekly_count" -gt "$WEEKLY_RETENTION" ]; then
        local to_delete=$((weekly_count - WEEKLY_RETENTION))
        log "  清理每周备份: 删除最旧的 ${to_delete} 个文件"
        ls -1t "$BACKUP_WEEKLY"/*.sql.gz 2>/dev/null | tail -n "$to_delete" | xargs rm -f
    fi
    
    # 每月备份：保留最近 N 个月
    local monthly_count
    monthly_count=$(ls -1 "$BACKUP_MONTHLY"/*.sql.gz 2>/dev/null | wc -l || echo 0)
    if [ "$monthly_count" -gt "$MONTHLY_RETENTION" ]; then
        local to_delete=$((monthly_count - MONTHLY_RETENTION))
        log "  清理每月备份: 删除最旧的 ${to_delete} 个文件"
        ls -1t "$BACKUP_MONTHLY"/*.sql.gz 2>/dev/null | tail -n "$to_delete" | xargs rm -f
    fi
    
    log "✅ 保留策略执行完毕"
}

# ==================== 通知 ====================

send_notification() {
    local status="$1"
    local message="$2"
    local backup_path="$3"
    
    if [ -z "$WECOM_WEBHOOK" ]; then
        log "⚠️ 未配置企业微信 Webhook，跳过通知"
        return 0
    fi
    
    local emoji="✅"
    local color="info"
    if [ "$status" = "failure" ]; then
        emoji="❌"
        color="warning"
    fi
    
    local backup_size="N/A"
    if [ -f "$backup_path" ]; then
        backup_size=$(du -sh "$backup_path" | cut -f1)
    fi
    
    local payload
    payload=$(cat <<EOF
{
    "msgtype": "markdown",
    "markdown": {
        "content": "## ${emoji} 数据库备份通知\n\n**数据库:** ${DB_NAME}\n**状态:** <font color=\"${color}\">${status}</font>\n**大小:** ${backup_size}\n**时间:** $(date '+%Y-%m-%d %H:%M:%S')\n\n${message}"
    }
}
EOF
)
    
    curl -s -X POST "$WECOM_WEBHOOK" \
        -H "Content-Type: application/json" \
        -d "$payload" > /dev/null 2>&1 || true
    
    log "📤 通知已发送"
}

# ==================== 主逻辑 ====================

log "========================================="
log "数据库备份开始 - ${DB_NAME}"
log "========================================="

BACKUP_PATH=""
STATUS="success"
MESSAGE=""

# 执行每日备份
log "📅 执行每日备份..."
BACKUP_PATH=$(do_full_backup "$BACKUP_DAILY")

# 周日执行每周备份
if [ "$DAY_OF_WEEK" = "7" ]; then
    log "📅 今天是周日，执行每周备份..."
    do_full_backup "$BACKUP_WEEKLY" > /dev/null
fi

# 每月1号执行每月备份
if [ "$DAY_OF_MONTH" = "01" ]; then
    log "📅 今天是月初，执行每月备份..."
    do_full_backup "$BACKUP_MONTHLY" > /dev/null
fi

# 清理过期备份
cleanup_old_backups

# 发送通知
send_notification "$STATUS" "每日全量备份完成" "$BACKUP_PATH"

log "========================================="
log "备份全部完成"
log "========================================="