#!/usr/bin/env python3
"""
Lightweight repository sanity checks suitable for GitHub Actions.
This is intentionally NOT a compiler for MQL5 (MetaEditor isn't available on CI).
"""

from __future__ import annotations

import os
import sys
from pathlib import Path


REPO_ROOT = Path(__file__).resolve().parents[1]
MQL5_DIR = REPO_ROOT / "mt5" / "MQL5"


def fail(msg: str) -> None:
    print(f"ERROR: {msg}", file=sys.stderr)
    raise SystemExit(1)


def iter_source_files() -> list[Path]:
    """⚡ Bolt: Use os.walk for faster directory traversal compared to rglob."""
    if not MQL5_DIR.exists():
        fail(f"Missing directory: {MQL5_DIR}")
    files: list[Path] = []
    # ⚡ Bolt: os.walk is significantly faster for deep hierarchies
    for root, _, filenames in os.walk(MQL5_DIR):
        for filename in filenames:
            if filename.lower().endswith((".mq5", ".mqh")):
                files.append(Path(root) / filename)

    if not files:
        fail(f"No .mq5/.mqh files found under {MQL5_DIR}")
    return sorted(files)


def check_no_nul_bytes(files: list[Path]) -> None:
    """⚡ Bolt: Use chunked reading to prevent loading large files into memory and exit early."""
    for p in files:
        # ⚡ Bolt: Chunked reading (64KB) is more memory efficient and allows early exit
        with open(p, "rb") as f:
            while chunk := f.read(65536):
                if b"\x00" in chunk:
                    fail(f"NUL byte found in {p.relative_to(REPO_ROOT)}")


def check_reasonable_size(files: list[Path]) -> None:
    # Avoid accidentally committing huge build artifacts.
    for p in files:
        # ⚡ Bolt: Metadata retrieval (size) is fast and doesn't read file content
        sz = p.stat().st_size
        if sz > 5_000_000:
            fail(f"Unexpectedly large source file (>5MB): {p.relative_to(REPO_ROOT)} ({sz} bytes)")


def main() -> int:
    files = iter_source_files()
    check_reasonable_size(files)  # Check size first to avoid reading huge files for NUL check
    check_no_nul_bytes(files)

    rel = [str(p.relative_to(REPO_ROOT)) for p in files]
    print("OK: found source files:")
    for r in rel:
        print(f"- {r}")
    return 0


if __name__ == "__main__":
    raise SystemExit(main())