#!/usr/bin/env python3
# Copyright (C) 2024-2026 Whiterun LLC,
# This software is licensed under the GNU Affero General Public License (AGPL), version 3.0 or later.,
# A copy of the license can be found in the LICENSE file or at https://www.gnu.org/licenses/agpl-3.0.html

import os
import sys
import re

"""
Disallow blocking write pool access (_w.get()) in RPC handlers.

Blocking .get() calls on write pools can exhaust Rocket's thread pool if a
background task holds the write lock for an extended period. All threads
waiting on .get() will block, causing the entire API to hang.

Use try_get() instead, which returns None immediately if the lock is unavailable.

OK (non-blocking):
    if let Some(cw) = dbp.cauldron_w.try_get() { ... }

NOT OK (blocks thread, can cause API hang):
    let cw = dbp.cauldron_w.get()?;
"""

OUR_PATH = os.path.dirname(os.path.realpath(__file__))

# Pattern to detect blocking write pool access: something_w.get()
FORBIDDEN_PATTERN = re.compile(r"\b\w+_w\.get\(\)")


def check_file_for_blocking_write_lock(file_path):
    """Check if the file contains blocking _w.get() calls outside of test modules."""
    violations = []

    with open(file_path, 'r', encoding='utf-8') as file:
        for line_num, line in enumerate(file, 1):
            # Stop checking if we enter test module
            if re.search(r"\bmod tests \{", line):
                break

            if FORBIDDEN_PATTERN.search(line):
                violations.append((line_num, line.strip()))

    return violations


def check_rpc_files():
    """
    Traverse src/rpc and check each .rs file for blocking write lock access.
    """
    rpc_dir = os.path.join(OUR_PATH, "..", "src", "rpc")
    found_violations = False

    for root, dirs, files in os.walk(rpc_dir):
        for file in files:
            if file.endswith('.rs'):
                file_path = os.path.join(root, file)
                violations = check_file_for_blocking_write_lock(file_path)

                if violations:
                    found_violations = True
                    rel_path = os.path.relpath(file_path, os.path.join(OUR_PATH, ".."))
                    for line_num, line in violations:
                        print(f"{rel_path}:{line_num}: blocking _w.get() found")
                        print(f"    {line}")
                        print(f"    hint: use try_get() instead to avoid thread exhaustion")
                        print()

    if found_violations:
        print("ERROR: Blocking write pool access found in RPC handlers.")
        print("This can cause API hangs if a background task holds the write lock.")
        sys.exit(1)
    else:
        print("OK")
        sys.exit(0)


if __name__ == "__main__":
    check_rpc_files()