# ════════════════════════════════════════════════════════════════
# tools/file_reader.py
# ════════════════════════════════════════════════════════════════
"""文件读取工具（从配置读取 allowed_root / max_file_size_kb）"""

from pathlib import Path
from tools.base_tool import BaseTool, ToolResult
from config.settings import settings


class FileReaderTool(BaseTool):
    name        = "file_reader"
    description = "读取本地文件内容，仅限配置的 allowed_root 目录"
    parameters  = {
        "path":     {"type": "string", "description": "文件路径（相对于 allowed_root）"},
        "encoding": {"type": "string", "description": "文件编码，默认 utf-8"},
    }

    def __init__(self):
        super().__init__()
        cfg                = settings.tools['file_reader']
        self._allowed_root = Path(cfg['allowed_root'])
        self._max_size_kb  = cfg['max_file_size_kb']
        self.logger.debug(
            f"⚙️  FileReader root={self._allowed_root}, "
            f"max_size={self._max_size_kb}KB"
        )

    def execute(self, path: str, encoding: str = "utf-8", **_) -> ToolResult:
        self._allowed_root.mkdir(parents=True, exist_ok=True)

        target = (self._allowed_root / path).resolve()
        if not str(target).startswith(str(self._allowed_root.resolve())):
            return ToolResult(success=False, output="❌ 拒绝访问: 路径超出允许范围")

        if not target.exists():
            self._create_demo_file(target)

        size_kb = target.stat().st_size / 1024
        if size_kb > self._max_size_kb:
            return ToolResult(
                success=False,
                output=f"❌ 文件过大: {size_kb:.1f}KB > 限制 {self._max_size_kb}KB",
            )

        try:
            content = target.read_text(encoding=encoding)
            return ToolResult(
                success=True,
                output=f"文件 [{path}] ({size_kb:.1f}KB):\n{content}",
                metadata={"path": str(target), "size_kb": size_kb},
            )
        except OSError as exc:
            return ToolResult(success=False, output=f"读取失败: {exc}")

    @staticmethod
    def _create_demo_file(path: Path) -> None:
        path.parent.mkdir(parents=True, exist_ok=True)
        path.write_text(
            '{\n  "app": "AgentDemo",\n  "version": "1.0.0",\n'
            '  "llm": "claude-sonnet-4-6",\n  "tools": ["calculator","web_search"]\n}\n',
            encoding="utf-8",
        )