"""
元素抽象层模块

定义统一的元素数据类，支持元素验证和未来扩展。
"""

from dataclasses import dataclass, field
from typing import Optional


@dataclass
class TextElement:
    """文本元素"""
    type: str = 'text'
    content: str = ''
    box: list = field(default_factory=lambda: [1, 1, 8, 1])
    font: dict = field(default_factory=dict)

    def __post_init__(self):
        """创建时验证"""
        if not isinstance(self.box, list) or len(self.box) != 4:
            raise ValueError("box 必须是包含 4 个数字的列表")


@dataclass
class ImageElement:
    """图片元素"""
    type: str = 'image'
    src: str = ''
    box: list = field(default_factory=lambda: [1, 1, 4, 3])

    def __post_init__(self):
        """创建时验证"""
        if not self.src:
            raise ValueError("图片元素必须指定 src")
        if not isinstance(self.box, list) or len(self.box) != 4:
            raise ValueError("box 必须是包含 4 个数字的列表")


@dataclass
class ShapeElement:
    """形状元素"""
    type: str = 'shape'
    shape: str = 'rectangle'
    box: list = field(default_factory=lambda: [1, 1, 2, 1])
    fill: Optional[str] = None
    line: Optional[dict] = None

    def __post_init__(self):
        """创建时验证"""
        if not isinstance(self.box, list) or len(self.box) != 4:
            raise ValueError("box 必须是包含 4 个数字的列表")


@dataclass
class TableElement:
    """表格元素"""
    type: str = 'table'
    data: list = field(default_factory=list)
    position: list = field(default_factory=lambda: [1, 1])
    col_widths: list = field(default_factory=list)
    style: dict = field(default_factory=dict)

    def __post_init__(self):
        """创建时验证"""
        if not self.data:
            raise ValueError("表格数据不能为空")
        if not isinstance(self.position, list) or len(self.position) != 2:
            raise ValueError("position 必须是包含 2 个数字的列表")


def create_element(elem_dict: dict):
    """
    元素工厂函数，从字典创建对应类型的元素对象

    Args:
        elem_dict: 元素字典，必须包含 type 字段

    Returns:
        对应类型的元素对象

    Raises:
        ValueError: 不支持的元素类型
    """
    elem_type = elem_dict.get('type')

    if elem_type == 'text':
        return TextElement(**elem_dict)
    elif elem_type == 'image':
        return ImageElement(**elem_dict)
    elif elem_type == 'shape':
        return ShapeElement(**elem_dict)
    elif elem_type == 'table':
        return TableElement(**elem_dict)
    else:
        raise ValueError(f"不支持的元素类型: {elem_type}")