"""
兑换码模型

定义余额兑换码相关的数据表结构。

设计说明：
- 兑换码支持批量生成、导入导出
- 记录完整的使用日志
- 支持设置有效期和使用限制
"""

from datetime import datetime, timezone
from enum import Enum
from typing import TYPE_CHECKING
from uuid import uuid4
import secrets
import string

from sqlalchemy import (
    BigInteger,
    Boolean,
    DateTime,
    Enum as SQLEnum,
    ForeignKey,
    Index,
    Integer,
    String,
    Text,
    func,
)
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.database import Base

if TYPE_CHECKING:
    from app.models.user import User


def generate_uuid() -> str:
    """生成 UUID 字符串"""
    return str(uuid4())


def utc_now() -> datetime:
    """获取当前 UTC 时间"""
    return datetime.now(timezone.utc)


def generate_redeem_code(length: int = 16) -> str:
    """
    生成兑换码
    
    格式：大写字母和数字，分段显示（如 XXXX-XXXX-XXXX-XXXX）
    排除容易混淆的字符：0/O, 1/I/L
    """
    # 可用字符集（排除易混淆字符）
    alphabet = "ABCDEFGHJKMNPQRSTUVWXYZ23456789"
    code = "".join(secrets.choice(alphabet) for _ in range(length))
    # 每 4 个字符用连字符分隔
    return "-".join(code[i:i + 4] for i in range(0, len(code), 4))


class RedeemCodeStatus(str, Enum):
    """兑换码状态枚举"""
    
    ACTIVE = "active"        # 可用
    USED = "used"            # 已使用
    DISABLED = "disabled"    # 已禁用
    EXPIRED = "expired"      # 已过期


class RedeemCodeBatch(Base):
    """
    兑换码批次模型
    
    用于管理批量生成的兑换码
    """

    __tablename__ = "redeem_code_batches"

    # 主键
    id: Mapped[str] = mapped_column(
        String(36),
        primary_key=True,
        default=generate_uuid,
        comment="批次唯一标识",
    )

    # 批次信息
    name: Mapped[str] = mapped_column(
        String(128),
        nullable=False,
        comment="批次名称",
    )
    description: Mapped[str | None] = mapped_column(
        Text,
        nullable=True,
        comment="批次描述",
    )

    # 面值（单位额度）
    face_value: Mapped[int] = mapped_column(
        BigInteger,
        nullable=False,
        comment="面值（单位额度，1000 = 1.00）",
    )

    # 数量统计
    total_count: Mapped[int] = mapped_column(
        Integer,
        default=0,
        nullable=False,
        comment="生成总数",
    )
    used_count: Mapped[int] = mapped_column(
        Integer,
        default=0,
        nullable=False,
        comment="已使用数量",
    )

    # 创建者
    created_by: Mapped[str] = mapped_column(
        String(36),
        ForeignKey("users.id", ondelete="SET NULL"),
        nullable=True,
        comment="创建者 ID",
    )

    # 时间戳
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        default=utc_now,
        server_default=func.now(),
        nullable=False,
        comment="创建时间",
    )

    # 关系
    codes: Mapped[list["RedeemCode"]] = relationship(
        "RedeemCode",
        back_populates="batch",
        lazy="selectin",
    )
    creator: Mapped["User"] = relationship(
        "User",
        lazy="selectin",
    )

    @property
    def display_face_value(self) -> str:
        """显示面值（2 位小数）"""
        return f"{self.face_value / 1000:.2f}"

    def __repr__(self) -> str:
        return f"<RedeemCodeBatch(id={self.id!r}, name={self.name!r})>"


class RedeemCode(Base):
    """
    兑换码模型
    
    单个兑换码记录
    """

    __tablename__ = "redeem_codes"
    __table_args__ = (
        Index("ix_redeem_codes_status_expires", "status", "expires_at"),
    )

    # 主键
    id: Mapped[str] = mapped_column(
        String(36),
        primary_key=True,
        default=generate_uuid,
        comment="兑换码记录唯一标识",
    )

    # 兑换码（唯一索引）
    code: Mapped[str] = mapped_column(
        String(32),
        unique=True,
        nullable=False,
        index=True,
        default=generate_redeem_code,
        comment="兑换码",
    )

    # 批次关联（可选）
    batch_id: Mapped[str | None] = mapped_column(
        String(36),
        ForeignKey("redeem_code_batches.id", ondelete="SET NULL"),
        nullable=True,
        index=True,
        comment="关联批次 ID",
    )

    # 面值（单位额度）
    face_value: Mapped[int] = mapped_column(
        BigInteger,
        nullable=False,
        comment="面值（单位额度，1000 = 1.00）",
    )

    # 状态
    status: Mapped[RedeemCodeStatus] = mapped_column(
        SQLEnum(RedeemCodeStatus),
        default=RedeemCodeStatus.ACTIVE,
        nullable=False,
        index=True,
        comment="兑换码状态",
    )

    # 使用限制
    max_uses: Mapped[int] = mapped_column(
        Integer,
        default=1,
        nullable=False,
        comment="最大使用次数",
    )
    used_count: Mapped[int] = mapped_column(
        Integer,
        default=0,
        nullable=False,
        comment="已使用次数",
    )

    # 有效期
    expires_at: Mapped[datetime | None] = mapped_column(
        DateTime(timezone=True),
        nullable=True,
        comment="过期时间",
    )

    # 使用信息
    used_by: Mapped[str | None] = mapped_column(
        String(36),
        ForeignKey("users.id", ondelete="SET NULL"),
        nullable=True,
        comment="使用者 ID（最后使用）",
    )
    used_at: Mapped[datetime | None] = mapped_column(
        DateTime(timezone=True),
        nullable=True,
        comment="使用时间（最后使用）",
    )

    # 备注
    remark: Mapped[str | None] = mapped_column(
        Text,
        nullable=True,
        comment="备注",
    )

    # 创建者
    created_by: Mapped[str | None] = mapped_column(
        String(36),
        ForeignKey("users.id", ondelete="SET NULL"),
        nullable=True,
        comment="创建者 ID",
    )

    # 时间戳
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        default=utc_now,
        server_default=func.now(),
        nullable=False,
        comment="创建时间",
    )
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        default=utc_now,
        onupdate=utc_now,
        server_default=func.now(),
        nullable=False,
        comment="更新时间",
    )

    # 关系
    batch: Mapped["RedeemCodeBatch | None"] = relationship(
        "RedeemCodeBatch",
        back_populates="codes",
        lazy="selectin",
    )
    usage_logs: Mapped[list["RedeemCodeUsageLog"]] = relationship(
        "RedeemCodeUsageLog",
        back_populates="redeem_code",
        lazy="selectin",
        order_by="desc(RedeemCodeUsageLog.created_at)",
    )

    @property
    def display_face_value(self) -> str:
        """显示面值（2 位小数）"""
        return f"{self.face_value / 1000:.2f}"

    @property
    def is_valid(self) -> bool:
        """检查兑换码是否有效"""
        if self.status != RedeemCodeStatus.ACTIVE:
            return False
        if self.used_count >= self.max_uses:
            return False
        if self.expires_at and self.expires_at < utc_now():
            return False
        return True

    def __repr__(self) -> str:
        return f"<RedeemCode(code={self.code!r}, status={self.status.value})>"


class RedeemCodeUsageLog(Base):
    """
    兑换码使用日志模型
    
    记录每次兑换的详细信息
    """

    __tablename__ = "redeem_code_usage_logs"
    __table_args__ = (
        Index("ix_redeem_usage_user_created", "user_id", "created_at"),
    )

    # 主键
    id: Mapped[str] = mapped_column(
        String(36),
        primary_key=True,
        default=generate_uuid,
        comment="日志唯一标识",
    )

    # 关联
    redeem_code_id: Mapped[str] = mapped_column(
        String(36),
        ForeignKey("redeem_codes.id", ondelete="CASCADE"),
        nullable=False,
        index=True,
        comment="关联兑换码 ID",
    )
    user_id: Mapped[str] = mapped_column(
        String(36),
        ForeignKey("users.id", ondelete="CASCADE"),
        nullable=False,
        index=True,
        comment="使用者 ID",
    )
    transaction_id: Mapped[str | None] = mapped_column(
        String(36),
        ForeignKey("balance_transactions.id", ondelete="SET NULL"),
        nullable=True,
        comment="关联交易记录 ID",
    )

    # 兑换信息快照
    code_snapshot: Mapped[str] = mapped_column(
        String(32),
        nullable=False,
        comment="兑换码快照",
    )
    face_value: Mapped[int] = mapped_column(
        BigInteger,
        nullable=False,
        comment="面值（单位额度）",
    )

    # 客户端信息
    ip_address: Mapped[str | None] = mapped_column(
        String(64),
        nullable=True,
        comment="客户端 IP",
    )
    user_agent: Mapped[str | None] = mapped_column(
        String(512),
        nullable=True,
        comment="User Agent",
    )

    # 时间戳
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        default=utc_now,
        server_default=func.now(),
        nullable=False,
        comment="使用时间",
    )

    # 关系
    redeem_code: Mapped["RedeemCode"] = relationship(
        "RedeemCode",
        back_populates="usage_logs",
        lazy="selectin",
    )
    user: Mapped["User"] = relationship(
        "User",
        lazy="selectin",
    )

    @property
    def display_face_value(self) -> str:
        """显示面值（2 位小数）"""
        return f"{self.face_value / 1000:.2f}"

    def __repr__(self) -> str:
        return (
            f"<RedeemCodeUsageLog(code={self.code_snapshot!r}, "
            f"user_id={self.user_id!r})>"
        )