from __future__ import annotations

from decimal import Decimal

from pydantic import BaseModel, Field, field_validator, model_validator

from app.enums.resource_capacity import ResourceCapacitySourceEnum, ResourceCapacityUnitEnum


class ResourceCapacityConfigUpdate(BaseModel):
    enabled: bool = Field(
        ...,
        description="是否开启容量管控。true=开启，false=关闭。全局配置关闭表示全局不限制；用户配置关闭表示该用户个人明确关闭限制，优先级高于全局。",
        examples=[True],
    )
    limit_value: Decimal | None = Field(
        None,
        description="容量数值，最小1，不能为负数，最多3位小数。例如：1、10、10.5、10.500。enabled=true 时必填。",
        examples=["10.500"],
    )
    limit_unit: ResourceCapacityUnitEnum | None = Field(
        None,
        description="容量单位枚举：MB=1024*1024字节，GB=1024*1024*1024字节，TB=1024*1024*1024*1024字节。enabled=true 时必填。",
        examples=[ResourceCapacityUnitEnum.GB.value],
    )

    @field_validator("limit_value")
    @classmethod
    def validate_limit_value(cls, value: Decimal | None) -> Decimal | None:
        if value is None:
            return value
        if value < Decimal("1"):
            raise ValueError("容量数值不能小于1")
        if value.as_tuple().exponent < -3:
            raise ValueError("容量数值最多支持3位小数")
        return value

    @model_validator(mode="after")
    def validate_enabled_payload(self) -> "ResourceCapacityConfigUpdate":
        if self.enabled:
            if self.limit_value is None:
                raise ValueError("开启容量管控时必须填写容量数值")
            if self.limit_unit is None:
                raise ValueError("开启容量管控时必须选择容量单位：MB、GB、TB")
        return self


class ResourceCapacityConfigOut(BaseModel):
    enabled: bool = Field(..., description="是否开启容量管控")
    limit_value: str = Field(..., description="容量数值字符串，最多3位小数")
    limit_unit: ResourceCapacityUnitEnum = Field(..., description="容量单位枚举：MB、GB、TB")
    limit_bytes: int = Field(..., ge=0, description="按单位换算后的字节数")


class ResourceCapacityUsageOut(BaseModel):
    enabled: bool = Field(..., description="当前用户最终是否启用容量管控")
    source: ResourceCapacitySourceEnum = Field(..., description="最终配置来源：user=用户个人配置，global=全局配置，disabled=容量管控未开启")
    has_user_config: bool = Field(..., description="该用户是否存在个人容量配置记录。注意：存在且 enabled=false 表示用户个人明确关闭限制")
    used_bytes: int = Field(..., ge=0, description="当前用户已用有效资源容量，来自 UserResourceTotalStat.active_size_bytes")
    available_bytes: int | None = Field(None, description="当前用户可用容量字节数。未开启容量管控时为 null")
    total_bytes: int | None = Field(None, description="当前用户总容量字节数。未开启容量管控时为 null")
    usage_percent: float | None = Field(None, description="当前用户容量使用百分比，未开启容量管控时为 null")
    exceeded: bool = Field(..., description="是否已超额。判断规则：enabled=true 且 used_bytes >= total_bytes")
    limit_value: str | None = Field(None, description="最终生效容量数值。未开启容量管控时为 null")
    limit_unit: ResourceCapacityUnitEnum | None = Field(None, description="最终生效容量单位。未开启容量管控时为 null")


class AdminUserResourceCapacityOut(BaseModel):
    has_user_config: bool = Field(..., description="该用户是否已单独设置容量配置")
    user_config: ResourceCapacityConfigOut | None = Field(None, description="用户个人容量配置。未单独设置时为 null")
    global_config: ResourceCapacityConfigOut = Field(..., description="当前全局容量配置")
    effective: ResourceCapacityUsageOut = Field(..., description="该用户最终生效的容量使用数据")