"""文件读取工具"""

from pathlib import Path
from typing import Optional, Type

from anyio import Path as AsyncPath
from pydantic import BaseModel, Field

from app.agent.tools.base import MoviePilotTool
from app.log import logger

# 最大读取大小 50KB
MAX_READ_SIZE = 50 * 1024


class ReadFileInput(BaseModel):
    """Input parameters for read file tool"""
    file_path: str = Field(..., description="The absolute path of the file to read")
    start_line: Optional[int] = Field(None, description="The starting line number (1-based, inclusive). If not provided, reading starts from the beginning of the file.")
    end_line: Optional[int] = Field(None, description="The ending line number (1-based, inclusive). If not provided, reading goes until the end of the file.")


class ReadFileTool(MoviePilotTool):
    name: str = "read_file"
    description: str = "Read the content of a text file. Supports reading by line range. Each read is limited to 50KB; content exceeding this limit will be truncated."
    args_schema: Type[BaseModel] = ReadFileInput

    def get_tool_message(self, **kwargs) -> Optional[str]:
        """根据参数生成友好的提示消息"""
        file_path = kwargs.get("file_path", "")
        file_name = Path(file_path).name if file_path else "未知文件"
        return f"正在读取文件: {file_name}"

    async def run(self, file_path: str, start_line: Optional[int] = None,
                  end_line: Optional[int] = None, **kwargs) -> str:
        logger.info(f"执行工具: {self.name}, 参数: file_path={file_path}, start_line={start_line}, end_line={end_line}")

        try:
            path = AsyncPath(file_path)

            if not await path.exists():
                return f"错误：文件 {file_path} 不存在"

            if not await path.is_file():
                return f"错误：{file_path} 不是一个文件"

            content = await path.read_text(encoding="utf-8")
            truncated = False

            if start_line is not None or end_line is not None:
                lines = content.splitlines(keepends=True)
                total_lines = len(lines)

                # 将行号转换为索引（1-based -> 0-based）
                s = (start_line - 1) if start_line and start_line >= 1 else 0
                e = end_line if end_line and end_line >= 1 else total_lines

                # 确保范围有效
                s = max(0, min(s, total_lines))
                e = max(s, min(e, total_lines))

                content = "".join(lines[s:e])

            # 检查大小限制
            content_bytes = content.encode("utf-8")
            if len(content_bytes) > MAX_READ_SIZE:
                content = content_bytes[:MAX_READ_SIZE].decode("utf-8", errors="ignore")
                truncated = True

            if truncated:
                return f"{content}\n\n[警告：文件内容已超过50KB限制，以上内容已被截断。请使用 start_line/end_line 参数分段读取。]"

            return content

        except PermissionError:
            return f"错误：没有权限读取 {file_path}"
        except UnicodeDecodeError:
            return f"错误：{file_path} 不是文本文件，无法读取"
        except Exception as e:
            logger.error(f"读取文件 {file_path} 时发生错误: {str(e)}", exc_info=True)
            return f"操作失败: {str(e)}"