"""MCP tool that reads text files from a configured source.
Registers the 'read_file' tool which returns file contents with a
max size and validates inputs before delegating to a FileSource.
"""
from __future__ import annotations
from typing import Optional
from mcp.server.fastmcp import FastMCP
from clients.github import GitHubClient
from config import HTTP_VERIFY, MAX_FILE_CHARS, PROJECT_ROOT
from core.errors import ValidationError
from core.models import SourceType
from sources.source_factory import get_file_source
def register(mcp: FastMCP, *, github_client: Optional[GitHubClient] = None) -> None: # CHANGED (DI)
@mcp.tool(name="read_file")
async def read_file(
source: SourceType = "local",
path: str = "",
repo_url: Optional[str] = None,
ref: str = "main",
max_chars: int = MAX_FILE_CHARS,
) -> str:
"""Read a text file from a source and return its UTF-8 contents.
Fetches a file from either a local filesystem or a GitHub repository.
Parameters:
- source: "local" or "github" (default: "local").
- path: file path relative to the source root (required).
- repo_url: required when source is "github" (e.g. https://github.com/owner/repo).
- ref: git reference to resolve (branch, tag, or SHA). Default: "main".
- max_chars: maximum characters to return (default from config).
Returns:
The file contents as a UTF-8 string. If the content exceeds max_chars
it will be truncated and the suffix "\n\n...[TRUNCATED]..." appended.
Raises:
ValidationError for missing/invalid inputs, and NotFoundError or
source-specific errors when the file or repository cannot be resolved.
"""
if not path or not path.strip():
raise ValidationError("Missing file path")
if source == "github" and (not repo_url or not repo_url.strip()):
raise ValidationError("Missing repo_url for github source")
src = get_file_source(
source,
project_root=PROJECT_ROOT,
repo_url=repo_url,
ref=ref,
http_verify=HTTP_VERIFY,
github_client=github_client,
)
return await src.read_file(path=path, max_chars=max_chars)
