#!/bin/bash
# ============================================================================
# MySQL 8.0.24 备份恢复工具 - 公共函数库
# ============================================================================
# 说明: 此文件包含所有脚本共用的函数
# ============================================================================

# 颜色定义 (用于终端输出)
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
BLUE='\033[0;34m'
NC='\033[0m' # No Color

# ============================================================================
# 日志函数
# ============================================================================

# 获取当前时间戳
get_timestamp() {
    date +"%Y-%m-%d %H:%M:%S"
}

# 打印信息日志
log_info() {
    local message="$1"
    echo -e "${GREEN}[INFO]${NC} [$(get_timestamp)] $message"
    if [[ -n "${LOG_FILE:-}" ]]; then
        echo "[INFO] [$(get_timestamp)] $message" >> "$LOG_FILE"
    fi
}

# 打印警告日志
log_warn() {
    local message="$1"
    echo -e "${YELLOW}[WARN]${NC} [$(get_timestamp)] $message" >&2
    if [[ -n "${LOG_FILE:-}" ]]; then
        echo "[WARN] [$(get_timestamp)] $message" >> "$LOG_FILE"
    fi
}

# 打印错误日志
log_error() {
    local message="$1"
    echo -e "${RED}[ERROR]${NC} [$(get_timestamp)] $message" >&2
    if [[ -n "${LOG_FILE:-}" ]]; then
        echo "[ERROR] [$(get_timestamp)] $message" >> "$LOG_FILE"
    fi
}

# 打印调试日志 (仅在 VERBOSE=true 时输出)
log_debug() {
    local message="$1"
    if [[ "${VERBOSE:-false}" == "true" ]]; then
        echo -e "${BLUE}[DEBUG]${NC} [$(get_timestamp)] $message"
        if [[ -n "${LOG_FILE:-}" ]]; then
            echo "[DEBUG] [$(get_timestamp)] $message" >> "$LOG_FILE"
        fi
    fi
}

# ============================================================================
# 错误处理函数
# ============================================================================

# 错误退出函数
die() {
    local message="$1"
    local exit_code="${2:-1}"
    log_error "$message"
    log_error "脚本异常退出，退出码: $exit_code"
    exit "$exit_code"
}

# 设置错误处理 trap
setup_error_trap() {
    # 捕获错误并输出详细信息
    trap 'error_handler $? $LINENO $BASH_LINENO "$BASH_COMMAND" $(printf "::%s" ${FUNCNAME[@]:-})' ERR
}

# 错误处理器
error_handler() {
    local exit_code=$1
    local line_no=$2
    local bash_lineno=$3
    local last_command=$4
    local func_trace=$5
    
    log_error "============================================================"
    log_error "脚本执行出错!"
    log_error "============================================================"
    log_error "退出码: $exit_code"
    log_error "错误行号: $line_no"
    log_error "失败命令: $last_command"
    log_error "函数调用栈: $func_trace"
    log_error "============================================================"
}

# ============================================================================
# 验证函数
# ============================================================================

# 检查是否以 root 用户运行
check_root() {
    if [[ $EUID -ne 0 ]]; then
        die "此脚本需要以 root 权限运行，请使用 sudo"
    fi
}

# 检查必要的命令是否存在
check_commands() {
    local commands=("$@")
    local missing=()
    
    for cmd in "${commands[@]}"; do
        if ! command -v "$cmd" &> /dev/null; then
            missing+=("$cmd")
        fi
    done
    
    if [[ ${#missing[@]} -gt 0 ]]; then
        die "缺少必要的命令: ${missing[*]}"
    fi
}

# 检查 MySQL 连接
check_mysql_connection() {
    log_info "检查 MySQL 连接..."
    
    local mysql_cmd="$MYSQL_PATH"
    local connect_args="-h${MYSQL_HOST} -P${MYSQL_PORT} -u${MYSQL_USER}"
    
    if [[ -n "$MYSQL_PASSWORD" ]]; then
        connect_args="$connect_args -p${MYSQL_PASSWORD}"
    fi
    
    if ! $mysql_cmd $connect_args -e "SELECT 1;" &> /dev/null; then
        die "无法连接到 MySQL 服务器 (${MYSQL_HOST}:${MYSQL_PORT})"
    fi
    
    log_info "MySQL 连接成功"
}

# 检查目录是否存在，不存在则创建
ensure_dir() {
    local dir="$1"
    if [[ ! -d "$dir" ]]; then
        log_info "创建目录: $dir"
        mkdir -p "$dir" || die "无法创建目录: $dir"
    fi
}

# 检查磁盘空间
check_disk_space() {
    local target_dir="$1"
    local required_mb="${2:-1024}"  # 默认需要 1GB
    
    # 获取目标目录所在分区的可用空间 (MB)
    local available_mb=$(df -m "$target_dir" | awk 'NR==2 {print $4}')
    
    if [[ $available_mb -lt $required_mb ]]; then
        die "磁盘空间不足! 需要: ${required_mb}MB, 可用: ${available_mb}MB"
    fi
    
    log_debug "磁盘空间检查通过: 需要 ${required_mb}MB, 可用 ${available_mb}MB"
}

# ============================================================================
# MySQL 操作函数
# ============================================================================

# 执行 MySQL 命令
execute_mysql() {
    local sql="$1"
    local mysql_cmd="$MYSQL_PATH"
    local connect_args="-h${MYSQL_HOST} -P${MYSQL_PORT} -u${MYSQL_USER}"
    
    if [[ -n "$MYSQL_PASSWORD" ]]; then
        connect_args="$connect_args -p${MYSQL_PASSWORD}"
    fi
    
    $mysql_cmd $connect_args -N -e "$sql" 2>&1
}

# 获取当前 binlog 位置
get_binlog_position() {
    local result=$(execute_mysql "SHOW MASTER STATUS\G")
    
    local binlog_file=$(echo "$result" | grep "File:" | awk '{print $2}')
    local binlog_pos=$(echo "$result" | grep "Position:" | awk '{print $2}')
    
    if [[ -z "$binlog_file" || -z "$binlog_pos" ]]; then
        die "无法获取 binlog 位置，请确保 MySQL 已启用 binlog"
    fi
    
    echo "${binlog_file}:${binlog_pos}"
}

# 获取所有数据库列表
get_databases() {
    local exclude_regex=""
    
    # 构建排除正则表达式
    for db in $EXCLUDE_DATABASES; do
        if [[ -n "$exclude_regex" ]]; then
            exclude_regex="${exclude_regex}|"
        fi
        exclude_regex="${exclude_regex}^${db}$"
    done
    
    # 获取数据库列表
    local databases=$(execute_mysql "SHOW DATABASES;")
    
    # 过滤排除的数据库
    if [[ -n "$exclude_regex" ]]; then
        databases=$(echo "$databases" | grep -vE "$exclude_regex")
    fi
    
    echo "$databases"
}

# ============================================================================
# 文件操作函数
# ============================================================================

# 压缩文件
compress_file() {
    local input_file="$1"
    local output_file="$2"
    
    log_info "压缩文件: $input_file -> $output_file"
    
    case "$COMPRESS_TOOL" in
        gzip)
            gzip -c "$input_file" > "$output_file" || die "压缩失败"
            ;;
        pigz)
            pigz -p "$COMPRESS_THREADS" -c "$input_file" > "$output_file" || die "压缩失败"
            ;;
        lz4)
            lz4 -c "$input_file" > "$output_file" || die "压缩失败"
            ;;
        *)
            die "不支持的压缩工具: $COMPRESS_TOOL"
            ;;
    esac
    
    log_info "压缩完成"
}

# 解压文件
decompress_file() {
    local input_file="$1"
    local output_file="$2"
    
    log_info "解压文件: $input_file -> $output_file"
    
    case "$input_file" in
        *.gz)
            gunzip -c "$input_file" > "$output_file" || die "解压失败"
            ;;
        *.lz4)
            lz4 -d -c "$input_file" > "$output_file" || die "解压失败"
            ;;
        *)
            # 假设是未压缩文件，直接复制
            cp "$input_file" "$output_file" || die "复制失败"
            ;;
    esac
    
    log_info "解压完成"
}

# 清理过期备份
cleanup_old_backups() {
    local backup_dir="$1"
    local retention_days="$2"
    
    log_info "清理 $retention_days 天前的备份: $backup_dir"
    
    local count=$(find "$backup_dir" -maxdepth 1 -type d -mtime +$retention_days 2>/dev/null | wc -l)
    
    if [[ $count -gt 0 ]]; then
        find "$backup_dir" -maxdepth 1 -type d -mtime +$retention_days -exec rm -rf {} \;
        log_info "已清理 $count 个过期备份目录"
    else
        log_info "没有需要清理的过期备份"
    fi
}

# ============================================================================
# 通知函数
# ============================================================================

# 发送通知
send_notification() {
    local subject="$1"
    local message="$2"
    
    if [[ "${ENABLE_EMAIL_NOTIFICATION:-false}" == "true" && -n "${NOTIFICATION_EMAIL:-}" ]]; then
        log_info "发送邮件通知到: $NOTIFICATION_EMAIL"
        echo "$message" | mail -s "$subject" "$NOTIFICATION_EMAIL" || log_warn "邮件发送失败"
    fi
}

# ============================================================================
# 锁文件函数 (防止并发执行)
# ============================================================================

# 获取锁
acquire_lock() {
    local lock_file="$1"
    local lock_name="${2:-backup}"
    
    if [[ -f "$lock_file" ]]; then
        local pid=$(cat "$lock_file")
        if kill -0 "$pid" 2>/dev/null; then
            die "${lock_name} 进程已在运行 (PID: $pid)"
        else
            log_warn "发现过期的锁文件，正在清理..."
            rm -f "$lock_file"
        fi
    fi
    
    echo $$ > "$lock_file" || die "无法创建锁文件"
    log_debug "已获取锁: $lock_file (PID: $$)"
}

# 释放锁
release_lock() {
    local lock_file="$1"
    
    if [[ -f "$lock_file" ]]; then
        rm -f "$lock_file"
        log_debug "已释放锁: $lock_file"
    fi
}

# ============================================================================
# 时间计算函数
# ============================================================================

# 计算执行时间
calculate_duration() {
    local start_time=$1
    local end_time=$2
    
    local duration=$((end_time - start_time))
    local hours=$((duration / 3600))
    local minutes=$(((duration % 3600) / 60))
    local seconds=$((duration % 60))
    
    printf "%02d:%02d:%02d" $hours $minutes $seconds
}

# 获取文件大小 (人类可读格式)
get_file_size() {
    local file="$1"
    
    if [[ -f "$file" ]]; then
        ls -lh "$file" | awk '{print $5}'
    elif [[ -d "$file" ]]; then
        du -sh "$file" | awk '{print $1}'
    else
        echo "N/A"
    fi
}