"""
tools/file_reader.py
文件读取工具 —— 读取本地文件内容，支持文本/JSON/CSV
配置通过 settings.tools['file_reader'] 读取
"""

import csv
import io
import json
from pathlib import Path

from config.settings import settings
from utils.logger import get_logger

logger = get_logger("TOOL.FileReader")


def _cfg(key: str, fallback=None):
    return settings.tools['file_reader'].get(key, fallback)


class FileReaderTool:
    name        = "file_reader"
    description = (
        "读取本地文件内容，支持 .txt / .md / .py / .json / .csv / .yaml / .log 等文本文件。"
        "文件必须位于 config.yaml file_reader.allowed_root 目录下。"
    )
    parameters  = {
        "type": "object",
        "properties": {
            "file_path": {
                "type":        "string",
                "description": "文件路径（相对于 allowed_root 或绝对路径）",
            },
            "encoding": {
                "type":        "string",
                "description": "文件编码，默认 utf-8",
            },
            "max_lines": {
                "type":        "integer",
                "description": "最多读取行数，0 表示全部读取",
            },
        },
        "required": ["file_path"],
    }

    _TEXT_EXTENSIONS = {
        ".txt", ".md", ".py", ".js", ".ts", ".java", ".c", ".cpp",
        ".h", ".hpp", ".go", ".rs", ".rb", ".php", ".sh", ".bash",
        ".yaml", ".yml", ".toml", ".ini", ".cfg", ".conf",
        ".json", ".csv", ".log", ".xml", ".html", ".css", ".sql",
        ".env", ".gitignore", ".dockerfile",
    }

    def execute(
        self,
        file_path: str = "",
        encoding:  str = "utf-8",
        max_lines: int = 0,
        **_,
    ) -> str:
        if not file_path or not file_path.strip():
            return "❌ 参数错误: file_path 不能为空"

        allowed_root = Path(_cfg('allowed_root', './workspace')).resolve()
        max_size_kb  = _cfg('max_file_size_kb', 512)

        # 路径解析
        path = Path(file_path)
        if not path.is_absolute():
            path = allowed_root / path
        path = path.resolve()

        logger.info(
            f"📄 读取文件: {path}\n"
            f"   allowed_root={allowed_root}  "
            f"max_size={max_size_kb}KB  [config]"
        )

        # 安全检查：必须在 allowed_root 内
        try:
            path.relative_to(allowed_root)
        except ValueError:
            return (
                f"❌ 安全限制: 文件路径超出允许范围\n"
                f"   路径: {path}\n"
                f"   允许范围: {allowed_root}\n"
                f"   请在 config.yaml → tools.file_reader.allowed_root 中调整"
            )

        if not path.exists():
            return f"❌ 文件不存在: {path}"
        if not path.is_file():
            return f"❌ 路径不是文件: {path}"

        # 文件大小检查
        size_kb = path.stat().st_size / 1024
        if size_kb > max_size_kb:
            return (
                f"❌ 文件过大: {size_kb:.1f} KB > 限制 {max_size_kb} KB\n"
                f"   请在 config.yaml → tools.file_reader.max_file_size_kb 中调整"
            )

        # 扩展名检查
        suffix = path.suffix.lower()
        if suffix not in self._TEXT_EXTENSIONS:
            return (
                f"❌ 不支持的文件类型: {suffix}\n"
                f"   支持类型: {', '.join(sorted(self._TEXT_EXTENSIONS))}"
            )

        # 读取文件
        try:
            if suffix == ".json":
                return self._read_json(path, encoding)
            if suffix == ".csv":
                return self._read_csv(path, encoding, max_lines)
            return self._read_text(path, encoding, max_lines)
        except UnicodeDecodeError:
            return (
                f"❌ 编码错误: 无法以 {encoding} 解码文件\n"
                f"   请尝试指定 encoding 参数，例如 'gbk' 或 'latin-1'"
            )
        except Exception as e:
            return f"❌ 读取失败: {e}"

    @staticmethod
    def _read_text(path: Path, encoding: str, max_lines: int) -> str:
        content = path.read_text(encoding=encoding)
        lines   = content.splitlines()
        total   = len(lines)
        if max_lines and max_lines < total:
            shown   = lines[:max_lines]
            omitted = total - max_lines
            text    = "\n".join(shown)
            return (
                f"📄 {path.name}  ({total} 行，显示前 {max_lines} 行)\n"
                f"{'─' * 50}\n{text}\n"
                f"{'─' * 50}\n... 还有 {omitted} 行未显示"
            )
        return f"📄 {path.name}  ({total} 行)\n{'─' * 50}\n{content}"

    @staticmethod
    def _read_json(path: Path, encoding: str) -> str:
        content = path.read_text(encoding=encoding)
        try:
            data      = json.loads(content)
            formatted = json.dumps(data, ensure_ascii=False, indent=2)
            return f"📄 {path.name}  (JSON)\n{'─' * 50}\n{formatted}"
        except json.JSONDecodeError as e:
            return f"⚠️  JSON 解析失败: {e}\n原始内容:\n{content[:500]}"

    @staticmethod
    def _read_csv(path: Path, encoding: str, max_lines: int) -> str:
        content = path.read_text(encoding=encoding)
        reader  = csv.reader(io.StringIO(content))
        rows    = list(reader)
        total   = len(rows)
        limit   = max_lines if max_lines else min(total, 50)
        shown   = rows[:limit]

        # 计算列宽
        if not shown:
            return f"📄 {path.name}  (CSV，空文件)"
        col_widths = [
            max(len(str(row[i])) if i < len(row) else 0 for row in shown)
            for i in range(len(shown[0]))
        ]
        lines = [f"📄 {path.name}  (CSV，{total} 行)", "─" * 50]
        for row in shown:
            cells = [
                str(row[i]).ljust(col_widths[i]) if i < len(row) else ""
                for i in range(len(shown[0]))
            ]
            lines.append(" | ".join(cells))
        if total > limit:
            lines.append(f"... 还有 {total - limit} 行未显示")
        return "\n".join(lines)