from pydantic import BaseModel, Field
from datetime import date, datetime
from typing import Optional, List


# ============ 财务账户 Schema ============

class AccountBase(BaseModel):
    """账户基础模型"""
    name: str = Field(..., min_length=1, max_length=100)
    account_type: str = Field(default="savings", pattern="^(savings|debt)$")
    balance: float = Field(default=0.0)
    icon: str = Field(default="wallet", max_length=50)
    color: str = Field(default="#FFB7C5", max_length=20)
    sort_order: int = Field(default=0)
    is_active: bool = Field(default=True)
    description: Optional[str] = None


class AccountCreate(AccountBase):
    """创建账户请求模型"""
    pass


class AccountUpdate(BaseModel):
    """更新账户请求模型"""
    name: Optional[str] = Field(None, max_length=100)
    account_type: Optional[str] = Field(None, pattern="^(savings|debt)$")
    balance: Optional[float] = None
    icon: Optional[str] = Field(None, max_length=50)
    color: Optional[str] = Field(None, max_length=20)
    sort_order: Optional[int] = None
    is_active: Optional[bool] = None
    description: Optional[str] = None


class AccountResponse(AccountBase):
    """账户响应模型"""
    id: int
    created_at: datetime
    updated_at: datetime

    class Config:
        from_attributes = True


class AccountListItemResponse(BaseModel):
    """账户列表项响应模型（含分期摘要）"""
    id: int
    name: str
    account_type: str
    balance: float
    icon: str
    color: str
    sort_order: int
    is_active: bool
    description: Optional[str] = None
    created_at: datetime
    updated_at: datetime
    installments: List[dict] = []


class BalanceUpdateRequest(BaseModel):
    """更新余额请求模型"""
    new_balance: float
    note: Optional[str] = Field(None, max_length=200)


# ============ 账户变更历史 Schema ============

class AccountHistoryResponse(BaseModel):
    """变更历史响应模型"""
    id: int
    account_id: int
    change_amount: float
    balance_before: float
    balance_after: float
    note: Optional[str] = None
    created_at: datetime

    class Config:
        from_attributes = True


# ============ 分期还款计划 Schema ============

class DebtInstallmentBase(BaseModel):
    """分期计划基础模型"""
    account_id: int
    total_amount: float
    total_periods: int = Field(..., ge=1)
    current_period: int = Field(default=1, ge=1)
    payment_day: int = Field(..., ge=1, le=31)
    payment_amount: float = Field(..., gt=0)
    start_date: date
    is_completed: bool = Field(default=False)


class DebtInstallmentCreate(DebtInstallmentBase):
    """创建分期计划请求模型"""
    pass


class DebtInstallmentUpdate(BaseModel):
    """更新分期计划请求模型"""
    account_id: Optional[int] = None
    total_amount: Optional[float] = None
    total_periods: Optional[int] = Field(None, ge=1)
    current_period: Optional[int] = Field(None, ge=1)
    payment_day: Optional[int] = Field(None, ge=1, le=31)
    payment_amount: Optional[float] = Field(None, gt=0)
    start_date: Optional[date] = None
    is_completed: Optional[bool] = None


class DebtInstallmentResponse(DebtInstallmentBase):
    """分期计划响应模型（含计算字段）"""
    id: int
    created_at: datetime
    updated_at: datetime

    # 计算字段
    next_payment_date: Optional[date] = None
    days_until_payment: Optional[int] = None
    remaining_periods: Optional[int] = None

    # 关联账户信息
    account_name: Optional[str] = None
    account_icon: Optional[str] = None
    account_color: Optional[str] = None

    class Config:
        from_attributes = True