Agent/agent/tools/builtin/file/read.py

"""
Read Tool - 文件读取工具

参考 OpenCode read.ts 完整实现。

核心功能：
- 支持文本文件、图片、PDF
- 分页读取（offset/limit）
- 二进制文件检测
- 行长度和字节限制
"""

import os
import base64
import mimetypes
from pathlib import Path
from typing import Optional
from urllib.parse import urlparse

import httpx

from agent.tools import tool, ToolResult, ToolContext

# 常量（参考 opencode）
DEFAULT_READ_LIMIT = 2000
MAX_LINE_LENGTH = 2000
MAX_BYTES = 50 * 1024  # 50KB


@tool(description="读取文件内容，支持文本文件、图片、PDF 等多种格式，也支持 HTTP/HTTPS URL")
async def read_file(
    file_path: str,
    offset: int = 0,
    limit: int = DEFAULT_READ_LIMIT,
    context: Optional[ToolContext] = None
) -> ToolResult:
    """
    读取文件内容

    参考 OpenCode 实现

    Args:
        file_path: 文件路径（绝对路径、相对路径或 HTTP/HTTPS URL）
        offset: 起始行号（从 0 开始）
        limit: 读取行数（默认 2000 行）
        context: 工具上下文

    Returns:
        ToolResult: 文件内容
    """
    # 检测是否为 HTTP/HTTPS URL
    parsed = urlparse(file_path)
    if parsed.scheme in ("http", "https"):
        return await _read_from_url(file_path)

    # 解析路径
    path = Path(file_path)
    if not path.is_absolute():
        path = Path.cwd() / path

    # 检查文件是否存在
    if not path.exists():
        # 尝试提供建议（参考 opencode:44-60）
        parent_dir = path.parent
        if parent_dir.exists():
            candidates = [
                f for f in parent_dir.iterdir()
                if path.name.lower() in f.name.lower() or f.name.lower() in path.name.lower()
            ][:3]

            if candidates:
                suggestions = "\n".join(str(c) for c in candidates)
                return ToolResult(
                    title=f"文件未找到: {path.name}",
                    output=f"文件不存在: {file_path}\n\n你是否想要:\n{suggestions}",
                    error="File not found"
                )

        return ToolResult(
            title="文件未找到",
            output=f"文件不存在: {file_path}",
            error="File not found"
        )

    # 检测文件类型
    mime_type, _ = mimetypes.guess_type(str(path))
    mime_type = mime_type or ""

    # 图片文件（参考 opencode:66-91）
    if mime_type.startswith("image/") and mime_type not in ["image/svg+xml", "image/vnd.fastbidsheet"]:
        try:
            raw = path.read_bytes()
            b64_data = base64.b64encode(raw).decode("ascii")
            return ToolResult(
                title=path.name,
                output=f"图片文件: {path.name} (MIME: {mime_type}, {len(raw)} bytes)",
                metadata={"mime_type": mime_type, "truncated": False},
                images=[{
                    "type": "base64",
                    "media_type": mime_type,
                    "data": b64_data,
                }],
            )
        except Exception as e:
            return ToolResult(
                title=path.name,
                output=f"图片文件读取失败: {path.name}: {e}",
                error=str(e),
            )

    # PDF 文件
    if mime_type == "application/pdf":
        return ToolResult(
            title=path.name,
            output=f"PDF 文件: {path.name}",
            metadata={"mime_type": mime_type, "truncated": False}
        )

    # 二进制文件检测（参考 opencode:156-211）
    if _is_binary_file(path):
        return ToolResult(
            title="二进制文件",
            output=f"无法读取二进制文件: {path.name}",
            error="Binary file"
        )

    # 读取文本文件（参考 opencode:96-143）
    try:
        with open(path, 'r', encoding='utf-8') as f:
            lines = f.readlines()

        total_lines = len(lines)
        end_line = min(offset + limit, total_lines)

        # 截取行并处理长度限制
        output_lines = []
        total_bytes = 0
        truncated_by_bytes = False

        for i in range(offset, end_line):
            line = lines[i].rstrip('\n\r')

            # 行长度限制（参考 opencode:104）
            if len(line) > MAX_LINE_LENGTH:
                line = line[:MAX_LINE_LENGTH] + "..."

            # 字节限制（参考 opencode:105-112）
            line_bytes = len(line.encode('utf-8')) + (1 if output_lines else 0)
            if total_bytes + line_bytes > MAX_BYTES:
                truncated_by_bytes = True
                break

            output_lines.append(line)
            total_bytes += line_bytes

        # 格式化输出（参考 opencode:114-134）
        formatted = []
        for idx, line in enumerate(output_lines):
            line_num = offset + idx + 1
            formatted.append(f"{line_num:5d}| {line}")

        output = "<file>\n" + "\n".join(formatted)

        last_read_line = offset + len(output_lines)
        has_more = total_lines > last_read_line
        truncated = has_more or truncated_by_bytes

        # 添加提示
        if truncated_by_bytes:
            output += f"\n\n(输出在 {MAX_BYTES} 字节处被截断。使用 'offset' 参数读取第 {last_read_line} 行之后的内容)"
        elif has_more:
            output += f"\n\n(文件还有更多内容。使用 'offset' 参数读取第 {last_read_line} 行之后的内容)"
        else:
            output += f"\n\n(文件结束 - 共 {total_lines} 行)"

        output += "\n</file>"

        # 预览（前 20 行）
        preview = "\n".join(output_lines[:20])

        return ToolResult(
            title=path.name,
            output=output,
            metadata={
                "preview": preview,
                "truncated": truncated,
                "total_lines": total_lines,
                "read_lines": len(output_lines)
            }
        )

    except UnicodeDecodeError:
        return ToolResult(
            title="编码错误",
            output=f"无法解码文件（非 UTF-8 编码）: {path.name}",
            error="Encoding error"
        )
    except Exception as e:
        return ToolResult(
            title="读取错误",
            output=f"读取文件时出错: {str(e)}",
            error=str(e)
        )


def _is_binary_file(path: Path) -> bool:
    """
    检测是否为二进制文件

    参考 OpenCode 实现
    """
    # 常见二进制扩展名
    binary_exts = {
        '.zip', '.tar', '.gz', '.exe', '.dll', '.so', '.class',
        '.jar', '.war', '.7z', '.doc', '.docx', '.xls', '.xlsx',
        '.ppt', '.pptx', '.odt', '.ods', '.odp', '.bin', '.dat',
        '.obj', '.o', '.a', '.lib', '.wasm', '.pyc', '.pyo'
    }

    if path.suffix.lower() in binary_exts:
        return True

    # 检查文件内容
    try:
        file_size = path.stat().st_size
        if file_size == 0:
            return False

        # 读取前 4KB
        buffer_size = min(4096, file_size)
        with open(path, 'rb') as f:
            buffer = f.read(buffer_size)

        # 检测 null 字节
        if b'\x00' in buffer:
            return True

        # 统计非打印字符（参考 opencode:202-210）
        non_printable = 0
        for byte in buffer:
            if byte < 9 or (13 < byte < 32):
                non_printable += 1

        # 如果超过 30% 是非打印字符，认为是二进制
        return non_printable / len(buffer) > 0.3

    except Exception:
        return False


async def _read_from_url(url: str) -> ToolResult:
    """
    从 HTTP/HTTPS URL 读取文件内容。

    主要用于图片等多媒体资源，自动转换为 base64。
    """
    try:
        async with httpx.AsyncClient(timeout=30.0, follow_redirects=True) as client:
            response = await client.get(url)
            response.raise_for_status()

            content_type = response.headers.get("content-type", "")
            raw = response.content

            # 从 URL 提取文件名
            from urllib.parse import urlparse
            parsed = urlparse(url)
            filename = Path(parsed.path).name or "downloaded_file"

            # 图片文件
            if content_type.startswith("image/") or any(url.lower().endswith(ext) for ext in [".jpg", ".jpeg", ".png", ".gif", ".webp", ".bmp"]):
                mime_type = content_type.split(";")[0] if content_type else "image/jpeg"
                b64_data = base64.b64encode(raw).decode("ascii")
                return ToolResult(
                    title=filename,
                    output=f"图片文件: {filename} (URL: {url}, MIME: {mime_type}, {len(raw)} bytes)",
                    metadata={"mime_type": mime_type, "url": url, "truncated": False},
                    images=[{
                        "type": "base64",
                        "media_type": mime_type,
                        "data": b64_data,
                    }],
                )

            # 文本文件
            if content_type.startswith("text/") or content_type == "application/json":
                text = raw.decode("utf-8", errors="replace")
                lines = text.split("\n")
                preview = "\n".join(lines[:20])
                return ToolResult(
                    title=filename,
                    output=f"<file>\n{text}\n</file>",
                    metadata={
                        "preview": preview,
                        "url": url,
                        "mime_type": content_type,
                        "total_lines": len(lines),
                    }
                )

            # 其他二进制文件
            return ToolResult(
                title=filename,
                output=f"二进制文件: {filename} (URL: {url}, {len(raw)} bytes)",
                metadata={"url": url, "mime_type": content_type, "size": len(raw)}
            )

    except httpx.HTTPStatusError as e:
        return ToolResult(
            title="HTTP 错误",
            output=f"无法下载文件: {url}\nHTTP {e.response.status_code}: {e.response.reason_phrase}",
            error=str(e)
        )
    except Exception as e:
        return ToolResult(
            title="下载失败",
            output=f"无法从 URL 读取文件: {url}\n错误: {str(e)}",
            error=str(e)
        )