#!/usr/bin/env python3
#
# ===-----------------------------------------------------------------------===#
#
# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
# See https://llvm.org/LICENSE.txt for license information.
# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#
# ===------------------------------------------------------------------------===#

"""
ClangTidy Test Helper
=====================

This script is used to simplify writing, running, and debugging tests compatible
with llvm-lit. By default it runs clang-tidy in fix mode and uses FileCheck to
verify messages and/or fixes.

For debugging, with --export-fixes, the tool simply exports fixes to a provided
file and does not run FileCheck.

Extra arguments, those after the first -- if any, are passed to either
clang-tidy or clang:
* Arguments between the first -- and second -- are clang-tidy arguments.
  * May be only whitespace if there are no clang-tidy arguments.
  * clang-tidy's --config would go here.
* Arguments after the second -- are clang arguments

Examples
--------

  // RUN: %check_clang_tidy %s llvm-include-order %t -- -- -isystem %S/Inputs

or

  // RUN: %check_clang_tidy %s llvm-include-order --export-fixes=fixes.yaml %t -std=c++20

Notes
-----
  -std=c++(98|11|14|17|20)-or-later:
    This flag will cause multiple runs within the same check_clang_tidy
    execution. Make sure you don't have shared state across these runs.
"""

import argparse
import os
import pathlib
import platform
import re
import subprocess
import sys
from typing import List, Tuple


def write_file(file_name: str, text: str) -> None:
    with open(file_name, "w", encoding="utf-8") as f:
        f.write(text)
        f.truncate()


def try_run(args: List[str], raise_error: bool = True) -> str:
    try:
        process_output = subprocess.check_output(args, stderr=subprocess.STDOUT).decode(
            errors="ignore"
        )
    except subprocess.CalledProcessError as e:
        process_output = e.output.decode(errors="ignore")
        print("%s failed:\n%s" % (" ".join(args), process_output))
        if raise_error:
            raise
    return process_output


# This class represents the appearance of a message prefix in a file.
class MessagePrefix:
    def __init__(self, label: str) -> None:
        self.has_message = False
        self.prefixes: List[str] = []
        self.label = label

    def check(self, file_check_suffix: str, input_text: str) -> bool:
        self.prefix = self.label + file_check_suffix
        self.has_message = self.prefix in input_text
        if self.has_message:
            self.prefixes.append(self.prefix)
        return self.has_message


class CheckRunner:
    def __init__(self, args: argparse.Namespace, extra_args: List[str]) -> None:
        self.resource_dir = args.resource_dir
        self.assume_file_name = args.assume_filename
        self.input_file_name = args.input_file_name
        self.check_name = args.check_name
        self.temp_file_name = args.temp_file_name
        self.original_file_name = self.temp_file_name + ".orig"
        self.expect_clang_tidy_error = args.expect_clang_tidy_error
        self.std = args.std
        self.check_suffix = args.check_suffix
        self.input_text = ""
        self.has_check_fixes = False
        self.has_check_messages = False
        self.has_check_notes = False
        self.expect_no_diagnosis = False
        self.export_fixes = args.export_fixes
        self.fixes = MessagePrefix("CHECK-FIXES")
        self.messages = MessagePrefix("CHECK-MESSAGES")
        self.notes = MessagePrefix("CHECK-NOTES")
        self.match_partial_fixes = args.match_partial_fixes

        file_name_with_extension = self.assume_file_name or self.input_file_name
        _, extension = os.path.splitext(file_name_with_extension)
        if extension not in [".c", ".hpp", ".m", ".mm"]:
            extension = ".cpp"
        self.temp_file_name = self.temp_file_name + extension

        self.clang_extra_args = []
        self.clang_tidy_extra_args = extra_args
        if "--" in extra_args:
            i = self.clang_tidy_extra_args.index("--")
            self.clang_extra_args = self.clang_tidy_extra_args[i + 1 :]
            self.clang_tidy_extra_args = self.clang_tidy_extra_args[:i]

        # If the test does not specify a config style, force an empty one; otherwise
        # auto-detection logic can discover a ".clang-tidy" file that is not related to
        # the test.
        if not any(
            [re.match("^-?-config(-file)?=", arg) for arg in self.clang_tidy_extra_args]
        ):
            self.clang_tidy_extra_args.append("--config={}")

        if extension in [".m", ".mm"]:
            self.clang_extra_args = [
                "-fobjc-abi-version=2",
                "-fobjc-arc",
                "-fblocks",
            ] + self.clang_extra_args

        self.clang_extra_args.append("-std=" + self.std)

        # Tests should not rely on STL being available, and instead provide mock
        # implementations of relevant APIs.
        self.clang_extra_args.append("-nostdinc++")

        if self.resource_dir is not None:
            self.clang_extra_args.append("-resource-dir=%s" % self.resource_dir)

    def read_input(self) -> None:
        # Use a "\\?\" prefix on Windows to handle long file paths transparently:
        # https://learn.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation
        file_name = self.input_file_name
        if platform.system() == "Windows":
            file_name = "\\\\?\\" + os.path.abspath(file_name)
        with open(file_name, "r", encoding="utf-8") as input_file:
            self.input_text = input_file.read()

    def get_prefixes(self) -> None:
        for suffix in self.check_suffix:
            if suffix and not re.match("^[A-Z0-9\\-]+$", suffix):
                sys.exit(
                    'Only A..Z, 0..9 and "-" are allowed in check suffixes list,'
                    + ' but "%s" was given' % suffix
                )

            file_check_suffix = ("-" + suffix) if suffix else ""

            has_check_fix = self.fixes.check(file_check_suffix, self.input_text)
            self.has_check_fixes = self.has_check_fixes or has_check_fix

            has_check_message = self.messages.check(file_check_suffix, self.input_text)
            self.has_check_messages = self.has_check_messages or has_check_message

            has_check_note = self.notes.check(file_check_suffix, self.input_text)
            self.has_check_notes = self.has_check_notes or has_check_note

            if has_check_note and has_check_message:
                sys.exit(
                    "Please use either %s or %s but not both"
                    % (self.notes.prefix, self.messages.prefix)
                )

            if not has_check_fix and not has_check_message and not has_check_note:
                self.expect_no_diagnosis = True

        expect_diagnosis = (
            self.has_check_fixes or self.has_check_messages or self.has_check_notes
        )
        if self.expect_no_diagnosis and expect_diagnosis:
            sys.exit(
                "%s, %s or %s not found in the input"
                % (
                    self.fixes.prefix,
                    self.messages.prefix,
                    self.notes.prefix,
                )
            )
        assert expect_diagnosis or self.expect_no_diagnosis

    def prepare_test_inputs(self) -> None:
        # Remove the contents of the CHECK lines to avoid CHECKs matching on
        # themselves.  We need to keep the comments to preserve line numbers while
        # avoiding empty lines which could potentially trigger formatting-related
        # checks.
        cleaned_test = re.sub("// *CHECK-[A-Z0-9\\-]*:[^\r\n]*", "//", self.input_text)
        write_file(self.temp_file_name, cleaned_test)
        write_file(self.original_file_name, cleaned_test)

    def run_clang_tidy(self) -> str:
        args = (
            [
                "clang-tidy",
                "--experimental-custom-checks",
                self.temp_file_name,
            ]
            + [
                (
                    "-fix"
                    if self.export_fixes is None
                    else "--export-fixes=" + self.export_fixes
                )
            ]
            + [
                "--checks=-*," + self.check_name,
            ]
            + self.clang_tidy_extra_args
            + ["--"]
            + self.clang_extra_args
        )
        if self.expect_clang_tidy_error:
            args.insert(0, "not")
        print("Running " + repr(args) + "...")
        clang_tidy_output = try_run(args)
        print("------------------------ clang-tidy output -----------------------")
        print(
            clang_tidy_output.encode(sys.stdout.encoding, errors="replace").decode(
                sys.stdout.encoding
            )
        )
        print("------------------------------------------------------------------")

        diff_output = try_run(
            ["diff", "-u", self.original_file_name, self.temp_file_name], False
        )
        print("------------------------------ Fixes -----------------------------")
        print(diff_output)
        print("------------------------------------------------------------------")
        return clang_tidy_output

    def check_no_diagnosis(self, clang_tidy_output: str) -> None:
        if clang_tidy_output != "":
            sys.exit("No diagnostics were expected, but found the ones above")

    def check_fixes(self) -> None:
        if self.has_check_fixes:
            try_run(
                [
                    "FileCheck",
                    "--input-file=" + self.temp_file_name,
                    self.input_file_name,
                    "--check-prefixes=" + ",".join(self.fixes.prefixes),
                    (
                        "--match-full-lines"
                        if not self.match_partial_fixes
                        else "--strict-whitespace"  # Keeping past behavior.
                    ),
                ]
            )

    def check_messages(self, clang_tidy_output: str) -> None:
        if self.has_check_messages:
            messages_file = self.temp_file_name + ".msg"
            write_file(messages_file, clang_tidy_output)
            try_run(
                [
                    "FileCheck",
                    "-input-file=" + messages_file,
                    self.input_file_name,
                    "-check-prefixes=" + ",".join(self.messages.prefixes),
                    "-implicit-check-not={{warning|error}}:",
                ]
            )

    def check_notes(self, clang_tidy_output: str) -> None:
        if self.has_check_notes:
            notes_file = self.temp_file_name + ".notes"
            filtered_output = [
                line
                for line in clang_tidy_output.splitlines()
                if not ("note: FIX-IT applied" in line)
            ]
            write_file(notes_file, "\n".join(filtered_output))
            try_run(
                [
                    "FileCheck",
                    "-input-file=" + notes_file,
                    self.input_file_name,
                    "-check-prefixes=" + ",".join(self.notes.prefixes),
                    "-implicit-check-not={{note|warning|error}}:",
                ]
            )

    def run(self) -> None:
        self.read_input()
        if self.export_fixes is None:
            self.get_prefixes()
        self.prepare_test_inputs()
        clang_tidy_output = self.run_clang_tidy()
        if self.expect_no_diagnosis:
            self.check_no_diagnosis(clang_tidy_output)
        elif self.export_fixes is None:
            self.check_fixes()
            self.check_messages(clang_tidy_output)
            self.check_notes(clang_tidy_output)


CPP_STANDARDS = [
    "c++98",
    "c++11",
    ("c++14", "c++1y"),
    ("c++17", "c++1z"),
    ("c++20", "c++2a"),
    ("c++23", "c++2b"),
    ("c++26", "c++2c"),
]
C_STANDARDS = ["c99", ("c11", "c1x"), "c17", ("c23", "c2x"), "c2y"]


def expand_std(std: str) -> List[str]:
    split_std, or_later, _ = std.partition("-or-later")

    if not or_later:
        return [split_std]

    for standard_list in (CPP_STANDARDS, C_STANDARDS):
        item = next(
            (
                i
                for i, v in enumerate(standard_list)
                if (split_std in v if isinstance(v, (list, tuple)) else split_std == v)
            ),
            None,
        )
        if item is not None:
            return [split_std] + [
                x if isinstance(x, str) else x[0] for x in standard_list[item + 1 :]
            ]
    return [std]


def csv(string: str) -> List[str]:
    return string.split(",")


def parse_arguments() -> Tuple[argparse.Namespace, List[str]]:
    parser = argparse.ArgumentParser(
        prog=pathlib.Path(__file__).stem,
        description=__doc__,
        formatter_class=argparse.RawDescriptionHelpFormatter,
    )
    parser.add_argument("-expect-clang-tidy-error", action="store_true")
    parser.add_argument("-resource-dir")
    parser.add_argument("-assume-filename")
    parser.add_argument("input_file_name")
    parser.add_argument("check_name")
    parser.add_argument("temp_file_name")
    parser.add_argument(
        "-check-suffix",
        "-check-suffixes",
        default=[""],
        type=csv,
        help="comma-separated list of FileCheck suffixes",
    )
    parser.add_argument(
        "-export-fixes",
        default=None,
        type=str,
        metavar="file",
        help="A file to export fixes into instead of fixing.",
    )
    parser.add_argument(
        "-std",
        type=csv,
        default=None,
        help="Passed to clang. Special -or-later values are expanded.",
    )
    parser.add_argument(
        "--match-partial-fixes",
        action="store_true",
        help="allow partial line matches for fixes",
    )

    args, extra_args = parser.parse_known_args()
    if args.std is None:
        _, extension = os.path.splitext(args.assume_filename or args.input_file_name)
        args.std = ["c99-or-later" if extension in [".c", ".m"] else "c++11-or-later"]

    return (args, extra_args)


def main() -> None:
    sys.stdout.reconfigure(encoding="utf-8")
    sys.stderr.reconfigure(encoding="utf-8")
    args, extra_args = parse_arguments()

    abbreviated_stds = args.std
    for abbreviated_std in abbreviated_stds:
        for std in expand_std(abbreviated_std):
            args.std = std
            CheckRunner(args, extra_args).run()


if __name__ == "__main__":
    main()
