from datetime import datetime
from typing import Literal, Optional

from pydantic import BaseModel, Field, model_validator


# ---------- 局部块更新 ----------

class BlockUpdate(BaseModel):
    level: int = Field(..., ge=1, le=6, description="标题等级 1=H1 … 6=H6")
    index: int = Field(..., ge=0, description="该等级标题在文档中的顺序下标（从 0 开始）")
    content: str = Field(..., description="该块的新内容（含标题行本身）")


# ---------- 请求 ----------

class CreateDocumentRequest(BaseModel):
    title: str = Field(..., max_length=255)
    content: str = Field(..., description="文档内容（Markdown），最大 200KB")
    format: Literal["markdown"] = "markdown"
    session_id: Optional[str] = Field(None, alias="sessionId")
    template_id: Optional[str] = Field(None, alias="templateId")

    model_config = {"populate_by_name": True}


class UpdateDocumentRequest(BaseModel):
    title: Optional[str] = Field(None, max_length=255)
    content: Optional[str] = Field(None, description="全量更新内容，与 blocks 二选一")
    blocks: Optional[list[BlockUpdate]] = Field(None, description="局部块更新，与 content 二选一")

    @model_validator(mode="after")
    def check_content_or_blocks(self) -> "UpdateDocumentRequest":
        if self.content is not None and self.blocks is not None:
            raise ValueError("content 与 blocks 不能同时传入")
        return self


# ---------- 响应 ----------

class DocumentResponse(BaseModel):
    id: str
    title: str
    content: str
    format: str
    session_id: Optional[str] = Field(None, serialization_alias="sessionId")
    template_id: Optional[str] = Field(None, serialization_alias="templateId")
    created_by: Optional[str] = Field(None, serialization_alias="createdBy")
    created_at: datetime = Field(..., serialization_alias="createdAt")
    updated_at: datetime = Field(..., serialization_alias="updatedAt")

    model_config = {"from_attributes": True, "populate_by_name": True}


class DocumentListItem(BaseModel):
    id: str
    title: str
    template_id: Optional[str] = Field(None, serialization_alias="templateId")
    created_at: datetime = Field(..., serialization_alias="createdAt")
    updated_at: datetime = Field(..., serialization_alias="updatedAt")

    model_config = {"from_attributes": True, "populate_by_name": True}


class Pagination(BaseModel):
    page: int
    page_size: int = Field(..., serialization_alias="pageSize")
    total: int
    total_pages: int = Field(..., serialization_alias="totalPages")

    model_config = {"populate_by_name": True}