import os
import subprocess
import logging
from datetime import datetime, timedelta, timezone
from pathlib import Path
import shutil
import time
import psycopg2
from psycopg2 import sql

# -------------------------
# 配置与日志
# -------------------------
def setup_logger():
    logger = logging.getLogger("pitr_recovery")
    logger.setLevel(logging.INFO)
    if not logger.handlers:
        log_dir = Path("logs")
        log_dir.mkdir(exist_ok=True)
        fh = logging.FileHandler(log_dir / "postgres_recovery.log", encoding="utf-8")
        ch = logging.StreamHandler()
        fmt = logging.Formatter('%(asctime)s - %(levelname)s - %(message)s')
        fh.setFormatter(fmt)
        ch.setFormatter(fmt)
        logger.addHandler(fh)
        logger.addHandler(ch)
    return logger

logger = setup_logger()

# -------------------------
# 基本路径/服务检测
# -------------------------
def get_postgres_data_dir():
    """获取 PostgreSQL 数据目录"""
    possible_paths = [
        Path(r"D:/app/postgresql/data"),
        Path(r"C:/Program Files/PostgreSQL/16/data"),
        Path(r"C:/Program Files/PostgreSQL/15/data"),
        Path(r"C:/Program Files/PostgreSQL/14/data"),
        Path(r"C:/Program Files/PostgreSQL/13/data"),
        Path(r"C:/Program Files/PostgreSQL/12/data"),
    ]
    env_path = os.environ.get('PGDATA')
    if env_path:
        p = Path(env_path)
        if p.exists():
            return p
    for p in possible_paths:
        if p.exists():
            return p
    raise FileNotFoundError("无法找到 PostgreSQL 数据目录，请设置 PGDATA 或检查常见路径。")

def get_postgres_bin_path():
    """获取 PostgreSQL bin 目录"""
    possible_paths = [
        Path(r"D:/app/postgresql/bin"),
        Path(r"C:/Program Files/PostgreSQL/16/bin"),
        Path(r"C:/Program Files/PostgreSQL/15/bin"),
        Path(r"C:/Program Files/PostgreSQL/14/bin"),
        Path(r"C:/Program Files/PostgreSQL/13/bin"),
        Path(r"C:/Program Files/PostgreSQL/12/bin"),
    ]
    env_path = os.environ.get('PG_BIN_PATH')
    if env_path:
        p = Path(env_path)
        if p.exists():
            return p
    for p in possible_paths:
        if p.exists():
            return p
    # 尝试从 PATH 中查找
    return None

def get_postgres_service_name():
    """检测 PostgreSQL 服务名称"""
    candidates = [
        "postgresql-x64-16",
        "postgresql-x64-15",
        "postgresql-x64-14",
        "postgresql-x64-13",
        "postgresql-x64-12",
        "postgresql"
    ]
    for svc in candidates:
        try:
            result = subprocess.run(
                ["sc", "query", svc], 
                capture_output=True, 
                text=True, 
                creationflags=subprocess.CREATE_NO_WINDOW
            )
            if "RUNNING" in result.stdout:
                return svc
        except Exception:
            continue
    return candidates[0]

def is_postgres_service_running():
    """检查 PostgreSQL 服务是否运行"""
    svc = get_postgres_service_name()
    try:
        result = subprocess.run(
            ["sc", "query", svc], 
            capture_output=True, 
            text=True, 
            creationflags=subprocess.CREATE_NO_WINDOW
        )
        return "RUNNING" in result.stdout
    except Exception:
        return False

def stop_postgres_service():
    """停止 PostgreSQL 服务"""
    svc = get_postgres_service_name()
    logger.info(f"停止 PostgreSQL 服务: {svc}")
    
    # 尝试 net stop
    r = subprocess.run(
        ["net", "stop", svc], 
        capture_output=True, 
        text=True, 
        creationflags=subprocess.CREATE_NO_WINDOW
    )
    if r.returncode == 0:
        logger.info("服务已停止")
        return True
    
    # 尝试 sc stop
    r = subprocess.run(
        ["sc", "stop", svc], 
        capture_output=True, 
        text=True, 
        creationflags=subprocess.CREATE_NO_WINDOW
    )
    if r.returncode == 0:
        logger.info("服务已停止 (sc stop)")
        return True
    
    # 尝试 taskkill
    logger.warning("通过服务接口无法停止，尝试 taskkill 强制结束 postgres.exe")
    subprocess.run(
        ["taskkill", "/F", "/IM", "postgres.exe"], 
        capture_output=True, 
        text=True, 
        creationflags=subprocess.CREATE_NO_WINDOW
    )
    
    # 确认服务已停止
    max_wait = 60  # 最大等待60秒
    for _ in range(max_wait // 5):
        if not is_postgres_service_running():
            logger.info("服务已确认停止")
            return True
        time.sleep(5)
    
    logger.error("服务停止超时")
    return False

def start_postgres_service():
    """启动 PostgreSQL 服务"""
    svc = get_postgres_service_name()
    logger.info(f"启动 PostgreSQL 服务: {svc}")
    try:
        r = subprocess.run(
            ["net", "start", svc], 
            capture_output=True, 
            text=True, 
            creationflags=subprocess.CREATE_NO_WINDOW
        )
        if r.returncode == 0:
            logger.info("服务已启动")
            return True
        
        r = subprocess.run(
            ["sc", "start", svc], 
            capture_output=True, 
            text=True, 
            creationflags=subprocess.CREATE_NO_WINDOW
        )
        if r.returncode == 0:
            logger.info("服务已启动 (sc start)")
            return True
        
        logger.error(f"启动服务失败: {r.stderr}")
        return False
    except Exception as e:
        logger.error(f"启动服务异常: {e}")
        return False

# -------------------------
# 基础备份（pg_basebackup）
# -------------------------
def perform_base_backup(pg_superuser='postgres', pg_password='abc@1234'):
    """执行基础备份"""
    pg_bin = get_postgres_bin_path()
    if not pg_bin:
        raise RuntimeError("无法找到 PostgreSQL bin 目录")
    
    pg_basebackup = pg_bin / "pg_basebackup.exe"
    now = datetime.now()
    dest = Path(f"E:/code/backup/postgres/base_backup/{now.strftime('%Y%m%d_%H%M%S')}")
    dest.mkdir(parents=True, exist_ok=True)
    
    cmd = [
        str(pg_basebackup), 
        "-D", str(dest), 
        "-F", "p", 
        "-X", "f", 
        "-P", 
        "-U", pg_superuser
    ]
    
    env = os.environ.copy()
    env['PGPASSWORD'] = pg_password
    
    logger.info("开始基础备份: " + " ".join(cmd))
    r = subprocess.run(
        cmd, 
        env=env, 
        capture_output=True, 
        text=True, 
        creationflags=subprocess.CREATE_NO_WINDOW
    )
    
    if r.returncode != 0:
        logger.error(r.stderr)
        raise RuntimeError("pg_basebackup 失败: " + r.stderr)
    
    # 验证备份完整性
    if not (dest / "backup_label").exists():
        raise RuntimeError("基础备份不完整，缺少 backup_label 文件")
    
    logger.info(f"基础备份完成: {dest}")
    return str(dest)

# -------------------------
# 检查数据库状态
# -------------------------
def check_database_status(dbname='postgres', user='postgres', password='abc@1234', 
                         host='localhost', port=5432):
    """
    检查数据库状态
    返回 (is_running, is_in_recovery)
    """
    try:
        conn = psycopg2.connect(
            dbname=dbname, 
            user=user, 
            password=password, 
            host=host, 
            port=port, 
            connect_timeout=5
        )
        conn.autocommit = True
        cur = conn.cursor()
        
        # 检查是否在恢复模式
        cur.execute("SELECT pg_is_in_recovery()")
        in_recovery = cur.fetchone()[0]
        
        cur.close()
        conn.close()
        
        return True, in_recovery
    except Exception:
        return False, False

# -------------------------
# 主恢复函数：恢复到基础备份
# -------------------------
def restore_to_base_backup(base_backup_dir):
    """
    执行基础备份恢复
    base_backup_dir: 基础备份目录路径
    """
    data_dir = get_postgres_data_dir()
    logger.info(f"开始恢复到基础备份: {base_backup_dir}")
    backup_data_dir = None

    try:
        # 1. 停止服务
        if not stop_postgres_service():
            raise RuntimeError("无法停止 PostgreSQL 服务")
        time.sleep(5)  # 等待服务完全停止

        # 2. 备份当前数据目录
        backup_data_dir = data_dir.with_name(
            data_dir.name + "_backup_" + datetime.now().strftime("%Y%m%d_%H%M%S")
        )
        logger.info(f"备份当前数据目录到: {backup_data_dir}")
        if backup_data_dir.exists():
            shutil.rmtree(backup_data_dir)
        shutil.copytree(data_dir, backup_data_dir)
        logger.info("备份完成")

        # 3. 安全清空数据目录（保留关键配置文件）
        logger.info("安全清空数据目录...")
        exclude_files = {"postgresql.conf", "pg_hba.conf", "pg_ident.conf"}
        for item in data_dir.iterdir():
            if item.name in exclude_files:
                logger.info(f"保留配置文件: {item.name}")
                continue
            try:
                if item.is_dir():
                    shutil.rmtree(item)
                else:
                    item.unlink()
            except Exception as e:
                logger.warning("删除 %s 失败: %s", item, e)
        logger.info("数据目录已清空")

        # 4. 恢复基础备份
        logger.info("恢复基础备份到数据目录...")
        shutil.copytree(base_backup_dir, data_dir, dirs_exist_ok=True)
        logger.info("基础备份已恢复")

        # 5. 删除恢复相关文件（确保不进入恢复模式）
        for recovery_file in ["recovery.signal", "standby.signal", "recovery.conf"]:
            file_path = data_dir / recovery_file
            if file_path.exists():
                logger.info(f"删除恢复文件: {recovery_file}")
                file_path.unlink()
        
        # 6. 清理postgresql.auto.conf中的恢复设置
        auto_conf = data_dir / "postgresql.auto.conf"
        if auto_conf.exists():
            logger.info("清理postgresql.auto.conf中的恢复设置")
            with open(auto_conf, "r", encoding="utf-8") as f:
                lines = f.readlines()
            
            # 过滤掉恢复相关设置
            new_lines = [
                line for line in lines 
                if not line.strip().startswith((
                    "restore_command", 
                    "recovery_target_time",
                    "recovery_target_timeline",
                    "recovery_target_action"
                ))
            ]
            
            with open(auto_conf, "w", encoding="utf-8") as f:
                f.writelines(new_lines)
        
        # 7. 启动服务
        if not start_postgres_service():
            raise RuntimeError("无法启动 PostgreSQL 服务")
        
        # 8. 验证服务状态
        max_retries = 10
        for i in range(max_retries):
            try:
                is_running, in_recovery = check_database_status()
                if is_running and not in_recovery:
                    logger.info("数据库已成功启动，不在恢复模式")
                    return True
                time.sleep(2)
            except Exception:
                if i == max_retries - 1:
                    logger.error("无法验证数据库状态")
                time.sleep(2)
        
        return True

    except Exception as e:
        logger.error(f"恢复到基础备份失败: {e}")
        # 回滚：恢复原始数据目录
        try:
            if backup_data_dir and backup_data_dir.exists():
                logger.info("开始回滚：恢复原始数据目录...")
                try:
                    stop_postgres_service()
                except:
                    pass
                
                # 清空当前数据目录
                for item in data_dir.iterdir():
                    try:
                        if item.is_dir():
                            shutil.rmtree(item)
                        else:
                            item.unlink()
                    except Exception as ex:
                        logger.warning("删除 %s 失败: %s", item, ex)
                
                # 复制备份回去
                shutil.copytree(backup_data_dir, data_dir, dirs_exist_ok=True)
                
                # 启动服务
                if start_postgres_service():
                    logger.info("回滚完成并已启动服务（原始数据已恢复）")
                else:
                    logger.error("回滚后启动服务失败，请手动检查")
        except Exception as roll_err:
            logger.error(f"回滚失败: {roll_err}")
        raise

# -------------------------
# 辅助：解析时间字符串 
# 下面的代码用不了，直接基础备份恢复
# -------------------------
def parse_target_time(t):
    """解析目标时间并转换为 UTC"""
    if isinstance(t, datetime):
        return t.astimezone(timezone.utc)
    
    # 尝试多种格式
    for fmt in ("%Y-%m-%d %H:%M:%S", "%Y-%m-%dT%H:%M:%S", "%Y-%m-%d %H:%M", "%Y-%m-%d"):
        try:
            dt = datetime.strptime(t, fmt)
            return dt.astimezone(timezone.utc)
        except Exception:
            continue
    
    raise ValueError("无法解析目标时间，请使用 'YYYY-MM-DD HH:MM:SS' 格式")

# -------------------------
# 检查恢复进度（通过数据库）
# -------------------------
def check_recovery_progress(dbname='postgres', user='postgres', password='abc@1234', 
                           host='localhost', port=5432, target_dt=None):
    """
    检查恢复进度
    返回 (in_recovery_bool, last_replay_timestamp_or_None, meets_target)
    """
    try:
        conn = psycopg2.connect(
            dbname=dbname, 
            user=user, 
            password=password, 
            host=host, 
            port=port, 
            connect_timeout=5
        )
        conn.autocommit = True
        cur = conn.cursor()
        
        # 检查是否在恢复模式
        cur.execute("SELECT pg_is_in_recovery()")
        in_recovery = cur.fetchone()[0]
        
        last_ts = None
        try:
            # 获取最后回放时间
            cur.execute("SELECT pg_last_xact_replay_timestamp()")
            res = cur.fetchone()[0]
            if res:
                last_ts = res.astimezone(timezone.utc)
        except Exception as e:
            logger.debug("查询 pg_last_xact_replay_timestamp 失败: %s", e)
        
        cur.close()
        conn.close()
        
        # 检查是否达到目标时间
        ok = False
        if target_dt and last_ts:
            # 允许30秒的时间差
            time_diff = (target_dt - last_ts).total_seconds()
            ok = time_diff <= 30
        
        return in_recovery, last_ts, ok
    except Exception as e:
        logger.debug("数据库连接/查询失败: %s", e)
        return None, None, False

# -------------------------
# 主恢复函数：PITR 恢复到指定时间点
# -------------------------

def restore_to_point_in_time(target_time, base_backup_dir, 
                            wal_archive_dir=r"E:\code\backup\postgres\wal_archive",
                            pg_superuser='postgres', pg_password='abc@1234', 
                            db_check_name='postgres', db_check_user='postgres', 
                            db_check_password='abc@1234', db_host='localhost', 
                            db_port=5432, max_wait_minutes=30):
    """
    执行时间点恢复 (PITR)
    target_time: 'YYYY-MM-DD HH:MM:SS' 或 datetime
    base_backup_dir: 基础备份目录
    wal_archive_dir: WAL归档目录
    """
    target_dt = parse_target_time(target_time)
    data_dir = get_postgres_data_dir()
    logger.info(f"PITR 开始: 目标时间 {target_dt}, 数据目录: {data_dir}, 基础备份: {base_backup_dir}")
    backup_data_dir = None

    try:
        # 1. 停止服务
        if not stop_postgres_service():
            raise RuntimeError("无法停止 PostgreSQL 服务")
        time.sleep(5)  # 等待服务完全停止

        # 2. 备份当前数据目录
        backup_data_dir = data_dir.with_name(
            data_dir.name + "_backup_" + datetime.now().strftime("%Y%m%d_%H%M%S")
        )
        logger.info(f"备份当前数据目录到: {backup_data_dir}")
        if backup_data_dir.exists():
            shutil.rmtree(backup_data_dir)
        shutil.copytree(data_dir, backup_data_dir)
        logger.info("备份完成")

        # 3. 安全清空数据目录（保留关键配置文件）
        logger.info("安全清空数据目录...")
        exclude_files = {"postgresql.conf", "pg_hba.conf", "pg_ident.conf"}
        for item in data_dir.iterdir():
            if item.name in exclude_files:
                logger.info(f"保留配置文件: {item.name}")
                continue
            try:
                if item.is_dir():
                    shutil.rmtree(item)
                else:
                    item.unlink()
            except Exception as e:
                logger.warning("删除 %s 失败: %s", item, e)
        logger.info("数据目录已清空")

        # 4. 恢复基础备份
        logger.info("恢复基础备份到数据目录...")
        shutil.copytree(base_backup_dir, data_dir, dirs_exist_ok=True)
        logger.info("基础备份已恢复")

        # 5. 创建恢复信号文件 (PostgreSQL 12+)
        recovery_signal = data_dir / "recovery.signal"
        logger.info(f"创建恢复信号: {recovery_signal}")
        recovery_signal.touch()

        # 6. 配置恢复参数
        auto_conf = data_dir / "postgresql.auto.conf"
        safe_wal_dir = wal_archive_dir.replace("\\", "/")
        restore_command = f'copy "{wal_archive_dir}\\%f" "%p"'
        
        logger.info(f"写入恢复配置到 {auto_conf}")
        with open(auto_conf, "w", encoding="utf-8") as f:
            f.write(f"restore_command = '{restore_command}'\n")
            f.write(f"recovery_target_time = '{target_dt.isoformat()}'\n")
            f.write("recovery_target_timeline = 'latest'\n")
        logger.info("恢复配置写入完成")

        # 7. 启动服务
        if not start_postgres_service():
            raise RuntimeError("无法启动 PostgreSQL 服务（恢复阶段）")
        logger.info("服务已启动，开始轮询恢复进度...")

        # 8. 等待恢复完成
        timeout = timedelta(minutes=max_wait_minutes)
        start_time = datetime.now(timezone.utc)
        last_logged = None
        recovery_completed = False
        recovery_signal_file = data_dir / "recovery.signal"

        while True:
            elapsed = datetime.now(timezone.utc) - start_time
            if elapsed > timeout:
                raise RuntimeError(f"恢复超时（超过 {max_wait_minutes} 分钟）")

            try:
                in_recovery, last_replay_ts, meets_target = check_recovery_progress(
                    dbname=db_check_name,
                    user=db_check_user,
                    password=db_check_password,
                    host=db_host,
                    port=db_port,
                    target_dt=target_dt
                )
            except Exception as e:
                logger.error(f"检查恢复进度时出错: {e}")
                in_recovery, last_replay_ts, meets_target = None, None, False

            # 可能无法连接（服务刚启动）
            if in_recovery is None:
                logger.info("尚未能连接到数据库，等待 5 秒后重试...")
                time.sleep(5)
                continue

            # 每分钟打印一次恢复进度
            current_time = datetime.now(timezone.utc).strftime("%H:%M:%S")
            if last_logged != current_time:
                if last_replay_ts:
                    time_diff = (target_dt - last_replay_ts).total_seconds()
                    logger.info(f"恢复进度: {last_replay_ts} (差 {time_diff:.1f} 秒)")
                else:
                    logger.info(f"恢复中... pg_is_in_recovery={in_recovery}")
                last_logged = current_time

            # 检查恢复完成条件（PostgreSQL 12+）
            if not in_recovery and not recovery_signal_file.exists():
                logger.info("恢复完成：数据库已退出恢复模式。")
                recovery_completed = True
                break
            elif meets_target:
                logger.info("已满足目标时间条件，等待最终完成...")
                time.sleep(5)
                continue

            # 继续等待
            time.sleep(5)

        if recovery_completed:
            logger.info(f"PITR 成功：数据库已恢复到目标时间 {target_dt}")
            return True
        else:
            logger.warning("恢复过程未正常完成")
            return True

    except Exception as e:
        logger.error(f"PITR 恢复失败: {e}")
        # 回滚：恢复原始数据目录
        try:
            if backup_data_dir and backup_data_dir.exists():
                logger.info("开始回滚：恢复原始数据目录...")
                try:
                    stop_postgres_service()
                except:
                    pass
                
                # 清空当前数据目录
                for item in data_dir.iterdir():
                    try:
                        if item.is_dir():
                            shutil.rmtree(item)
                        else:
                            item.unlink()
                    except Exception as ex:
                        logger.warning("删除 %s 失败: %s", item, ex)
                
                # 复制备份回去
                shutil.copytree(backup_data_dir, data_dir, dirs_exist_ok=True)
                
                # 清理恢复标识文件
                for fn in ("recovery.signal", "postgresql.auto.conf"):
                    p = data_dir / fn
                    if p.exists():
                        try:
                            p.unlink()
                        except Exception:
                            pass
                
                # 启动服务
                if start_postgres_service():
                    logger.info("回滚完成并已启动服务（原始数据已恢复）")
                else:
                    logger.error("回滚后启动服务失败，请手动检查")
        except Exception as roll_err:
            logger.error(f"回滚失败: {roll_err}")
        raise