import os
from pathlib import Path

from mcp.server.fastmcp import FastMCP

mcp = FastMCP("filesystem", host="0.0.0.0", port=8010)


def _allowed_roots() -> list[Path]:
    roots_raw = os.getenv("MCP_FILESYSTEM_ROOTS", "/workspace").split(",")
    roots = [Path(root.strip()).resolve() for root in roots_raw if root.strip()]
    return roots or [Path("/workspace").resolve()]


def _resolve(path: str) -> Path:
    candidate = Path(path)
    if not candidate.is_absolute():
        candidate = Path("/workspace") / candidate
    resolved = candidate.resolve()

    for root in _allowed_roots():
        try:
            resolved.relative_to(root)
            return resolved
        except ValueError:
            continue

    allowed = ", ".join(str(r) for r in _allowed_roots())
    raise ValueError(f"Path '{resolved}' is outside allowed roots: {allowed}")


@mcp.tool()
def list_roots() -> list[str]:
    """List configured filesystem roots that this MCP server can access."""
    return [str(root) for root in _allowed_roots()]


@mcp.tool()
def list_dir(path: str = ".") -> list[str]:
    """List entries in a directory relative to an allowed root."""
    target = _resolve(path)
    if not target.exists() or not target.is_dir():
        raise ValueError(f"Not a directory: {target}")

    items = []
    for entry in sorted(target.iterdir(), key=lambda p: p.name.lower()):
        suffix = "/" if entry.is_dir() else ""
        items.append(f"{entry.name}{suffix}")
    return items


@mcp.tool()
def read_text(path: str, max_chars: int = 50000) -> str:
    """Read text from a file in an allowed root."""
    target = _resolve(path)
    if not target.exists() or not target.is_file():
        raise ValueError(f"Not a file: {target}")

    content = target.read_text(encoding="utf-8")
    return content[:max_chars]


@mcp.tool()
def write_text(path: str, content: str, append: bool = False) -> str:
    """Write text to a file in an allowed root."""
    target = _resolve(path)
    target.parent.mkdir(parents=True, exist_ok=True)

    mode = "a" if append else "w"
    with target.open(mode, encoding="utf-8") as fh:
        fh.write(content)

    return str(target)


@mcp.tool()
def find_files(path: str = ".", pattern: str = "*") -> list[str]:
    """Find files by glob pattern under a path in an allowed root."""
    target = _resolve(path)
    if not target.exists() or not target.is_dir():
        raise ValueError(f"Not a directory: {target}")

    return [str(p) for p in target.rglob(pattern) if p.is_file()]


if __name__ == "__main__":
    mcp.run(transport="sse")