from datetime import datetime
from uuid import UUID

from pydantic import BaseModel, ConfigDict, Field, model_validator


class InitializeRequest(BaseModel):
    username: str = Field(min_length=3, max_length=64, pattern=r"^[A-Za-z0-9_.-]+$")
    password: str = Field(min_length=12, max_length=256)


class LoginRequest(BaseModel):
    username: str
    password: str


class UserOut(BaseModel):
    model_config = ConfigDict(from_attributes=True)
    id: UUID
    username: str


class SessionOut(BaseModel):
    model_config = ConfigDict(from_attributes=True)
    id: UUID
    current: bool
    created_at: datetime
    last_seen_at: datetime
    expires_at: datetime
    ip_address: str | None
    user_agent: str | None


class NameUpdate(BaseModel):
    name: str = Field(min_length=1, max_length=120)


class FolderCreate(NameUpdate):
    pass


class FolderOut(BaseModel):
    model_config = ConfigDict(from_attributes=True)
    id: UUID
    name: str


class ListCreate(BaseModel):
    name: str = Field(min_length=1, max_length=120)
    folder_id: UUID | None = None


class ListOut(BaseModel):
    model_config = ConfigDict(from_attributes=True)
    id: UUID
    folder_id: UUID | None
    name: str
    is_inbox: bool


class TagCreate(BaseModel):
    name: str = Field(min_length=1, max_length=80)
    color: str = Field(default="#f15a29", min_length=1, max_length=32)


class TagOut(BaseModel):
    model_config = ConfigDict(from_attributes=True)
    id: UUID
    name: str
    color: str


class TaskCreate(BaseModel):
    title: str = Field(min_length=1, max_length=500)
    list_id: UUID
    description: str = ""
    priority: int = Field(default=0, ge=0, le=3)
    due_at: datetime | None = None
    parent_id: UUID | None = None
    tag_ids: list[UUID] = Field(default_factory=list)


class TaskUpdate(BaseModel):
    title: str | None = Field(default=None, min_length=1, max_length=500)
    description: str | None = None
    priority: int | None = Field(default=None, ge=0, le=3)
    due_at: datetime | None = None
    completed: bool | None = None
    list_id: UUID | None = None
    tag_ids: list[UUID] | None = None
    version: int = Field(ge=1)

    @model_validator(mode="after")
    def reject_null_non_nullable_fields(self):
        for field in ("title", "description", "priority", "completed", "list_id"):
            if field in self.model_fields_set and getattr(self, field) is None:
                raise ValueError(f"{field} cannot be null")
        return self


class TaskOut(BaseModel):
    model_config = ConfigDict(from_attributes=True)
    id: UUID
    list_id: UUID
    parent_id: UUID | None
    title: str
    description: str
    priority: int
    completed: bool
    due_at: datetime | None
    version: int


class TaskDetailOut(TaskOut):
    tags: list[TagOut] = Field(default_factory=list)
    subtasks: list[TaskOut] = Field(default_factory=list)


class TaskPage(BaseModel):
    items: list[TaskDetailOut]
    next_cursor: str | None = None
    total: int = 0
    page: int = 1
    page_size: int = 50


class BatchTaskUpdate(BaseModel):
    task_ids: list[UUID] = Field(min_length=1)
    completed: bool | None = None
    list_id: UUID | None = None
    due_at: datetime | None = None
    tag_ids: list[UUID] | None = None
    soft_delete: bool | None = None

    @model_validator(mode="after")
    def require_operation(self):
        operations = {"completed", "list_id", "due_at", "tag_ids", "soft_delete"}
        if not self.model_fields_set.intersection(operations):
            raise ValueError("at least one batch operation is required")
        if self.soft_delete is False:
            raise ValueError("soft_delete can only be true")
        return self


class BatchResult(BaseModel):
    updated: int