#!/usr/bin/env python3

import os
import pathlib
import re
import subprocess
import sys

# Ensure copyright headers match this format and are followed by a blank line:
# /*
#  * Copyright (c) YYYY(-YYYY), Whatever
#  * ... more of these ...
#  *
#  * SPDX-License-Identifier: BSD-2-Clause
#  */
GOOD_LICENSE_HEADER_PATTERN = re.compile(
    "^/\\*\n"
    + "( \\* Copyright \\(c\\) [0-9]{4}(-([0-9]{4}|present))?, .*\n)+"
    + " \\*\n"
    + " \\* SPDX-License-Identifier: BSD-2-Clause\n"
    + " \\*/\n"
    + "\n"
)
LICENSE_HEADER_CHECK_EXCLUDES = {
    "AK/Checked.h",
    "AK/Function.h",
    "Libraries/LibCore/SocketpairWindows.cpp",
}

# We check that "#pragma once" is present
PRAGMA_ONCE_STRING = "#pragma once"

# We make sure that there's a blank line before and after pragma once
GOOD_PRAGMA_ONCE_PATTERN = re.compile("(^|\\S\n\n)#pragma once(\n\n\\S.|$)")

# Make sure that all includes are either system includes or immediately resolvable local includes
ANY_INCLUDE_PATTERN = re.compile('^ *# *include\\b.*[>"](?!\\)).*$', re.M)
SYSTEM_INCLUDE_PATTERN = re.compile("^ *# *include *<([^>]+)>(?: /[*/].*)?$")
LOCAL_INCLUDE_PATTERN = re.compile('^ *# *include *"([^>]+)"(?: /[*/].*)?$')

INCLUDE_CHECK_EXCLUDES = {}

LOCAL_INCLUDE_ROOT_OVERRIDES = {}

LOCAL_INCLUDE_SUFFIX_EXCLUDES = [
    # Some Qt files are required to include their .moc files, which will be located in a deep
    # subdirectory that we won't find from here.
    ".moc",
]

# We check for and disallow any comments linking to the single-page HTML spec because it takes a long time to load.
SINGLE_PAGE_HTML_SPEC_LINK = re.compile("//.*https://html\\.spec\\.whatwg\\.org/#")

# We similarily check and disallow AD-HOCs and FIXMEs that aren't followed by a colon.
INVALID_AD_HOC_OR_FIXME = re.compile(r'^(?:[\s\d./\-(*]+(?:AD-HOC|FIXME|NB|NOTE)[^:]|.*"FIXME[^:"]).*$', re.MULTILINE)


def should_check_file(filename):
    if not filename.endswith(".cpp") and not filename.endswith(".h") and not filename.endswith(".rs"):
        return False
    if filename.startswith("Base/"):
        return False
    if filename.startswith("Meta/CMake/vcpkg/overlay-ports/"):
        return False
    return True


def find_files_here_or_argv():
    if len(sys.argv) > 1:
        raw_list = sys.argv[1:]
    else:
        process = subprocess.run(["git", "ls-files"], check=True, capture_output=True)
        raw_list = process.stdout.decode().strip("\n").split("\n")

    return filter(should_check_file, raw_list)


def is_in_prefix_list(filename, prefix_list):
    return any(filename.startswith(prefix) for prefix in prefix_list)


def find_matching_prefix(filename, prefix_list):
    matching_prefixes = [prefix for prefix in prefix_list if filename.startswith(prefix)]
    assert len(matching_prefixes) <= 1
    return matching_prefixes[0] if matching_prefixes else None


def run():
    errors_license = []
    errors_pragma_once_bad = []
    errors_pragma_once_missing = []
    errors_include_libc = []
    errors_include_weird_format = []
    errors_include_missing_local = []
    errors_include_bad_complex = []
    errors_single_page_html_spec = []
    errors_invalid_ad_hoc_or_fixme = {}

    for filename in find_files_here_or_argv():
        with open(filename, mode="r", encoding="utf-8") as f:
            file_content = f.read()
        if not is_in_prefix_list(filename, LICENSE_HEADER_CHECK_EXCLUDES):
            if not GOOD_LICENSE_HEADER_PATTERN.search(file_content):
                errors_license.append(filename)
        if filename.endswith(".rs"):
            continue
        if filename.endswith(".h"):
            if GOOD_PRAGMA_ONCE_PATTERN.search(file_content):
                # Excellent, the formatting is correct.
                pass
            elif PRAGMA_ONCE_STRING in file_content:
                # Bad, the '#pragma once' is present but it's formatted wrong.
                errors_pragma_once_bad.append(filename)
            else:
                # Bad, the '#pragma once' is missing completely.
                errors_pragma_once_missing.append(filename)
        if not is_in_prefix_list(filename, INCLUDE_CHECK_EXCLUDES):
            if include_root := find_matching_prefix(filename, LOCAL_INCLUDE_ROOT_OVERRIDES):
                local_include_root = pathlib.Path(include_root)
            else:
                local_include_root = pathlib.Path(filename).parent
            for include_line in ANY_INCLUDE_PATTERN.findall(file_content):
                if SYSTEM_INCLUDE_PATTERN.match(include_line):
                    # Don't try to resolve system-style includes, as these might depend on generators.
                    continue
                local_match = LOCAL_INCLUDE_PATTERN.match(include_line)
                if local_match is None:
                    print(f"Cannot parse include-line '{include_line}' in {filename}")
                    if filename not in errors_include_weird_format:
                        errors_include_weird_format.append(filename)
                    continue

                relative_filename = local_match.group(1)
                referenced_file = local_include_root.joinpath(relative_filename)

                if referenced_file.suffix in LOCAL_INCLUDE_SUFFIX_EXCLUDES:
                    continue

                if not referenced_file.exists():
                    print(f"In {filename}: Cannot find {referenced_file}")
                    if filename not in errors_include_missing_local:
                        errors_include_missing_local.append(filename)
        if SINGLE_PAGE_HTML_SPEC_LINK.search(file_content):
            errors_single_page_html_spec.append(filename)
        invalid_ad_hocs_or_fixmes = INVALID_AD_HOC_OR_FIXME.findall(file_content)
        if invalid_ad_hocs_or_fixmes:
            errors_invalid_ad_hoc_or_fixme[filename] = invalid_ad_hocs_or_fixmes

    have_errors = False
    if errors_license:
        print("Files with bad licenses:", " ".join(errors_license))
        have_errors = True
    if errors_pragma_once_missing:
        print("Files without #pragma once:", " ".join(errors_pragma_once_missing))
        have_errors = True
    if errors_pragma_once_bad:
        print("Files with a bad #pragma once:", " ".join(errors_pragma_once_bad))
        have_errors = True
    if errors_include_libc:
        print(
            "Files that include a LibC header using #include <LibC/...>:",
            " ".join(errors_include_libc),
        )
        have_errors = True
    if errors_include_weird_format:
        print(
            "Files that contain badly-formatted #include statements:",
            " ".join(errors_include_weird_format),
        )
        have_errors = True
    if errors_include_missing_local:
        print(
            "Files that #include a missing local file:",
            " ".join(errors_include_missing_local),
        )
        have_errors = True
    if errors_include_bad_complex:
        print(
            "Files that include a non-AK complex header:",
            " ".join(errors_include_bad_complex),
        )
        have_errors = True
    if errors_single_page_html_spec:
        print("Files with links to the single-page HTML spec:", " ".join(errors_single_page_html_spec))
        have_errors = True
    if errors_invalid_ad_hoc_or_fixme:
        for file in errors_invalid_ad_hoc_or_fixme:
            print(f"{file} contains invalid AD-HOC or FIXME usages:", "".join(errors_invalid_ad_hoc_or_fixme[file]))
        have_errors = True

    if have_errors:
        sys.exit(1)


if __name__ == "__main__":
    os.chdir(os.path.dirname(__file__) + "/../..")
    run()