import fnmatch
import os
from pathlib import Path


EXCLUDED_PARTS = {
    "bin", "obj", ".git", ".vs", ".harness", "testresults",
    "generated", "vendor", "third_party", "external",
}


def is_excluded_path(path: Path, root: Path, extra=()) -> bool:
    root = root.resolve()
    candidate = path if path.is_absolute() else root / path
    try:
        relative = candidate.relative_to(root)
        resolved_relative = candidate.resolve().relative_to(root)
    except ValueError:
        return True
    parts = tuple(part.lower() for part in relative.parts)
    if any(part in EXCLUDED_PARTS for part in parts):
        return True
    if parts[:2] == ("tests", "fixtures"):
        return True
    resolved_parts = tuple(part.lower() for part in resolved_relative.parts)
    if any(part in EXCLUDED_PARTS for part in resolved_parts) or resolved_parts[:2] == ("tests", "fixtures"):
        return True
    name = relative.as_posix().lower()
    return any(
        fnmatch.fnmatchcase(name, pattern.replace("\\", "/").lower())
        or name.startswith(pattern.replace("\\", "/").lower().rstrip("/") + "/")
        for pattern in extra
    )


def iter_source_files(root: Path):
    """Walk repository inputs, pruning artifacts and external/cyclic links."""
    root = root.resolve()
    seen = set()
    def fail(error):
        raise error

    for directory, directories, files in os.walk(root, followlinks=False, onerror=fail):
        current = Path(directory)
        resolved = current.resolve()
        if resolved in seen or is_excluded_path(current, root):
            directories[:] = []
            continue
        seen.add(resolved)
        directories[:] = sorted(
            name for name in directories
            if not is_excluded_path(current / name, root)
            and (current / name).resolve() not in seen
        )
        for name in sorted(files):
            path = current / name
            if not is_excluded_path(path, root):
                yield path