#!/usr/bin/env python3
"""
D4 — driver-manager-audit-no-stubs.py

Static-analysis gate for the § 0.5 comprehensive implementation principle
(see `local/docs/DRIVER-MANAGER-MIGRATION-PLAN.md` § 0.5).

Four rules:
- R1: stub macros (`unimplemented!()` / `todo!()` / `unreachable!()`) in
  production paths.
- R2: empty catch-all match arms (`_ => {}`).
- R3: `DriverParams::default()` returns in concrete drivers.
- R5: stub-macro calls inside Driver trait method bodies — distinguish
  from test-only usage.

Whitelisted: tests under `#[cfg(test)]`, examples, doc-tests.

Returns exit 0 on a clean audit, 1 otherwise.
"""

from __future__ import annotations

import os
import re
import subprocess
import sys
from pathlib import Path
from typing import Iterator

REPO_ROOT = Path("/mnt/data/Builds/RedBear-OS")
SCAN_ROOTS = [
    REPO_ROOT / "local/recipes/system/driver-manager/source",
    REPO_ROOT / "local/recipes/drivers/redox-driver-core/source",
    REPO_ROOT / "local/recipes/drivers/redox-driver-pci/source",
    REPO_ROOT / "local/recipes/drivers/redox-driver-sys/source",
]
RUST_EXT = ".rs"

# Lines to skip — match by exact suffix.
SKIP_LINE_SUFFIXES = (
    "unimplemented!()",
    "todo!()",
    "unreachable!()",
)

# R5: stub macros that are particularly suspect inside callback / fn bodies.
# We only flag these in production paths (i.e. not in #[cfg(test)] modules).
STUB_MACRO_PATTERN = (
    r"\b(?:unimplemented|todo|unreachable)!\(\)",
    "R5",
    "stub macro left in callback / fn body",
)

# Match-block skip:
#   `_ => { }` or `_ => {}` (empty body)
EMPTY_CATCH_ALL = re.compile(r"^\s*_?\s*=>\s*\{\s*\}\s*,?\s*$")

# Default trait method returning Ok(()) in lifecycle hooks:
#   fn probe(...) -> ProbeResult { ... Ok(()) skip ... }
#   fn remove(...) -> Result<...> { ... Ok(()) skip ... }
TRAIT_LIFECYCLE_OK_BODY = re.compile(
    r"^\s*Ok\s*\(\s*\)\s*,?\s*$"
)

# Default DriverParams::default() return in concrete driver impl.
DRIVER_PARAMS_DEFAULT = re.compile(r"\bDriverParams::default\s*\(\s*\)")


def iter_rust_files() -> Iterator[Path]:
    for root in SCAN_ROOTS:
        if not root.exists():
            continue
        for path in sorted(root.rglob(f"*{RUST_EXT}")):
            # Skip vendored or generated directories if any ever appear.
            if "/target/" in str(path):
                continue
            yield path


def file_is_test_only(path: Path, content: str) -> bool:
    """Return True if every top-level item in this file is gated by
    `#[cfg(test)]` (i.e. helper files for tests, doc tests, fixtures)."""
    test_count = content.count("#[cfg(test)]")
    if test_count == 0:
        return False
    non_test_items = 0
    fn_count = content.count("\nfn ")
    struct_count = content.count("\nstruct ")
    enum_count = content.count("\nenum ")
    impl_count = content.count("\nimpl ")
    non_test_items = fn_count + struct_count + enum_count + impl_count
    # Be conservative: only treat as test-only if `#[cfg(test)]` appears
    # at module level (outside any inner `mod tests { ... }`).
    if content.lstrip().startswith("#[cfg(test)]"):
        return True
    return False


def audit_file(path: Path) -> list[tuple[int, str, str]]:
    """Return a list of (line_no, rule_id, message) violations for one file."""
    content = path.read_text(encoding="utf-8", errors="replace")
    lines = content.splitlines()
    is_test_only = file_is_test_only(path, content)
    out: list[tuple[int, str, str]] = []

    for line_no, line in enumerate(lines, start=1):
        stripped = line.strip()
        if not stripped or stripped.startswith("//"):
            continue

        # Rule R1 — direct stub-macro calls.
        for suffix in SKIP_LINE_SUFFIXES:
            if stripped.endswith(suffix) or f".{suffix}" in stripped:
                if not is_test_only:
                    out.append(
                        (
                            line_no,
                            "R1",
                            f"`{suffix}` is a stub. Implement the case (see § 0.5).",
                        )
                    )

        # Rule R2 — empty catch-all in matches.
        if EMPTY_CATCH_ALL.match(line):
            # Heuristic: empty body is fine in some contexts (e.g. specific
            # feature flags), but only flag when there's a preceding match.
            # We just flag with a low-severity tag.
            out.append(
                (
                    line_no,
                    "R2",
                    "empty catch-all match arm `_ => {}` — confirm this is intentional",
                )
            )

        # Rule R3 — DriverParams::default() returns in production code.
        if not is_test_only and DRIVER_PARAMS_DEFAULT.search(line):
            out.append(
                (
                    line_no,
                    "R3",
                    "`DriverParams::default()` is a stub for production drivers — define real params",
                )
            )

        for pattern, rule_id, message in [STUB_MACRO_PATTERN]:
            if is_test_only:
                break
            import re as _re
            if _re.search(pattern, stripped):
                out.append((line_no, rule_id, message))

    return out


def main() -> int:
    violations_total = 0
    files_scanned = 0
    files_clean = 0

    for path in iter_rust_files():
        files_scanned += 1
        violations = audit_file(path)
        if not violations:
            files_clean += 1
            continue
        violations_total += len(violations)
        for line_no, rule_id, message in violations:
            rel = path.relative_to(REPO_ROOT)
            print(f"{rel}:{line_no}: [{rule_id}] {message}")

    print()
    print(f"=== driver-manager-audit-no-stubs.py ===")
    print(f"files scanned: {files_scanned}")
    print(f"files clean:   {files_clean}")
    print(f"violations:    {violations_total}")
    print(f"root:          {REPO_ROOT}")
    print(
        "rules:         R1 (stub macros), R2 (empty catch-all), R3 (DriverParams::default),"
    )
    print("               R5 (todo!/unimplemented! in callbacks)")
    if violations_total > 0:
        print()
        print("FAIL — driver-manager has unresolved § 0.5 comprehensive-implementation violations.")
        print("Fix every violation above and re-run. See migration plan § 5.1 D4 exit criteria.")
        return 1
    print()
    print("OK — every scanned file passes the § 0.5 stub-audit.")
    return 0


if __name__ == "__main__":
    sys.exit(main())