"""read_file.py – tool for reading files inside the sandbox."""

from __future__ import annotations

from typing import TYPE_CHECKING

from langchain_core.tools import BaseTool, tool
from loguru import logger

if TYPE_CHECKING:
    from docker_agent_sandbox.sandbox import DockerSandbox


def make_read_file_tool(sandbox: "DockerSandbox") -> BaseTool:
    """Return a read_file tool bound to *sandbox*."""

    @tool
    def read_file(path: str, offset: int = 0, length: int = 5000) -> str:
        """
        Read a file at *path*.

        *path* can be absolute (``/tmp/re-agent/result.csv``) or relative to the
        working directory.

        *offset* is the number of bytes to skip from the start of the file.
        *length* is the maximum number of bytes to return.  If the file is
        longer than ``offset + length``, the output is trimmed and a summary
        line is appended showing how many bytes were omitted.

        Returns the (possibly trimmed) file contents as text, or an error message.
        """
        logger.debug(
            "Reading file inside sandbox: {} offset={} length={}", path, offset, length
        )
        try:
            data = sandbox.read_file(path)
        except (FileNotFoundError, IsADirectoryError, RuntimeError) as exc:
            return f"[ERROR reading {path!r}] {exc}"

        total = len(data)
        chunk = data[offset : offset + length]
        text = chunk.decode("utf-8", errors="replace")

        suffix = ""
        if offset + length < total:
            remaining = total - (offset + length)
            suffix = f"\n[... {remaining} more bytes not shown (total {total} bytes). Use offset/length to read further.]"
        elif offset > 0 or total > length:
            suffix = f"\n[File total: {total} bytes, showing {len(chunk)} bytes from offset {offset}.]"
        return text + suffix

    return read_file