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

from __future__ import annotations

from shlex import quote
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
        )
        exit_code, wc_out = sandbox.exec(f"wc -c -- {quote(path)}")
        if exit_code != 0:
            return f"[ERROR reading {path!r}] {wc_out.strip()}"
        try:
            total = int(wc_out.split()[0])
        except (ValueError, IndexError):
            return f"[ERROR parsing file size for {path!r}] {wc_out.strip()}"

        exit_code, chunk = sandbox.exec(
            f"dd if={quote(path)} iflag=skip_bytes,count_bytes"
            f" skip={offset} count={length} 2>/dev/null"
        )
        if exit_code != 0:
            return f"[ERROR reading {path!r}] {chunk.strip()}"

        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)} chars from offset {offset}.]"
        return chunk + suffix

    return read_file