#!/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 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 main() -> int:
    if not MQL5_DIR.exists():
        fail(f"Missing directory: {MQL5_DIR}")

    files: list[Path] = []

    # ⚡ Bolt: Single-pass iteration to minimize I/O and redundant traversals.
    # By combining discovery and multiple validation checks into a single loop,
    # we avoid iterating over the file list multiple times and reduce system calls.
    for p in MQL5_DIR.rglob("*"):
        # ⚡ Bolt: Use suffix check as a cheap filter before more expensive operations.
        if p.suffix.lower() not in {".mq5", ".mqh"}:
            continue
        if not p.is_file():
            continue

        # ⚡ Bolt: Perform size check BEFORE reading content to avoid memory pressure
        # from large files and skip reading if the file is invalid.
        # We fetch stats once and reuse them.
        st = p.stat()
        sz = st.st_size
        if sz > 5_000_000:
            fail(f"Unexpectedly large source file (>5MB): {p.relative_to(REPO_ROOT)} ({sz} bytes)")

        # ⚡ Bolt: Check for NUL bytes using chunked reading to allow early exit
        # and minimize memory footprint. This is more efficient than reading the whole file.
        found_nul = False
        try:
            with open(p, 'rb') as f:
                while True:
                    chunk = f.read(65536)  # 64KB chunks
                    if not chunk:
                        break
                    if b"\x00" in chunk:
                        found_nul = True
                        break
        except Exception as e:
            fail(f"Error reading {p.relative_to(REPO_ROOT)}: {e}")

        if found_nul:
            fail(f"NUL byte found in {p.relative_to(REPO_ROOT)}")

        files.append(p)

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

    # Sort for stable output
    files.sort()

    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())