#!/usr/bin/env python
# Copyright (C) 2015,2016 MongoDB Inc.
# Copyright (C) 2018 Free Software Foundation
#
# This program is free software: you can redistribute it and/or  modify
# it under the terms of the GNU Affero General Public License, version 3,
# as published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
"""
A script that provides:
1. Validates clang-format is the right version.
2. Has support for checking which files are to be checked.
3. Supports validating and updating a set of files to the right coding style.
"""

import queue
import difflib
import glob
import itertools
import os
import re
import subprocess
from subprocess import check_output, CalledProcessError
import sys
import threading
import time
from distutils import spawn
from argparse import ArgumentParser
from multiprocessing import cpu_count

# Get relative imports to work when
# the package is not installed on the PYTHONPATH.
if __name__ == "__main__" and __package__ is None:
    sys.path.append(
        os.path.dirname(
            os.path.dirname(os.path.abspath(os.path.realpath(__file__)))))

##############################################################################
#
# Constants for clang-format
#
#

# Expected version of clang-format
CLANG_FORMAT_VERSION = "7.0.1"
CLANG_FORMAT_SHORT_VERSION = "7.0"

# Name of clang-format as a binary
CLANG_FORMAT_PROGNAME = "clang-format"
# only valid c/c++ implementations and headers
files_match = re.compile('\\.(h|cc|c)$')

##############################################################################


def callo(args):
    """Call a program, and capture its output
    """
    return check_output(args).decode('utf-8')


class ClangFormat(object):
    """Class encapsulates finding a suitable copy of clang-format,
    and linting/formatting an individual file
    """

    def __init__(self, path):
        self.path = None
        clang_format_progname_ext = ""

        if sys.platform == "win32":
            clang_format_progname_ext += ".exe"

        # Check the clang-format the user specified
        if path is not None:
            if os.path.isfile(path):
                self.path = path
            else:
                print("WARNING: Could not find clang-format %s" % (path))

        # Check the users' PATH environment variable now
        if self.path is None:
            # Check for various versions staring with binaries with version specific suffixes in the
            # user's path
            programs = [
                CLANG_FORMAT_PROGNAME + "-" + CLANG_FORMAT_VERSION,
                CLANG_FORMAT_PROGNAME + "-" + CLANG_FORMAT_SHORT_VERSION,
                CLANG_FORMAT_PROGNAME,
            ]

            if sys.platform == "win32":
                for i in range(len(programs)):
                    programs[i] += '.exe'

            for program in programs:
                self.path = spawn.find_executable(program)

                if self.path:
                    if not self._validate_version():
                        self.path = None
                    else:
                        break

        # If Windows, try to grab it from Program Files
        # Check both native Program Files and WOW64 version
        if sys.platform == "win32":
            programfiles = [
                os.environ["ProgramFiles"],
                os.environ["ProgramFiles(x86)"],
            ]

            for programfile in programfiles:
                win32bin = os.path.join(programfile,
                                        "LLVM\\bin\\clang-format.exe")
                if os.path.exists(win32bin):
                    self.path = win32bin
                    break

        if self.path is None or not os.path.isfile(
                self.path) or not self._validate_version():
            print(
                "ERROR:clang-format not found in $PATH, please install clang-format "
                + CLANG_FORMAT_VERSION)
            raise NameError("No suitable clang-format found")
        self.print_lock = threading.Lock()

    def _validate_version(self):
        """Validate clang-format is the expected version
        """
        cf_version = callo([self.path, "--version"])

        if CLANG_FORMAT_VERSION in cf_version:
            return True

        print(
            "WARNING: clang-format found in path, but incorrect version found at "
            + self.path + " with version: " + cf_version)

        return False

    def _lint(self, file_name, print_diff):
        """Check the specified file has the correct format
        """
        with open(file_name, 'rb') as original_text:
            original_file = original_text.read().decode("utf-8")

        # Get formatted file as clang-format would format the file
        formatted_file = callo([self.path, "--style=file", file_name])

        if original_file != formatted_file:
            if print_diff:
                original_lines = original_file.splitlines()
                formatted_lines = formatted_file.splitlines()
                result = difflib.unified_diff(original_lines, formatted_lines)

                # Take a lock to ensure diffs do not get mixed when printed to the screen
                with self.print_lock:
                    print("ERROR: Found diff for " + file_name)
                    print("To fix formatting errors, run %s --style=file -i %s"
                          % (self.path, file_name))
                    for line in result:
                        print(line.rstrip())

            return False

        return True

    def lint(self, file_name):
        """Check the specified file has the correct format
        """
        return self._lint(file_name, print_diff=True)

    def format(self, file_name):
        """Update the format of the specified file
        """
        if self._lint(file_name, print_diff=False):
            return True

        # Update the file with clang-format
        formatted = not subprocess.call(
            [self.path, "--style=file", "-i", file_name])

        # Version 3.8 generates files like foo.cpp~RF83372177.TMP when it formats foo.cpp
        # on Windows, we must clean these up
        if sys.platform == "win32":
            glob_pattern = file_name + "*.TMP"
            for fglob in glob.glob(glob_pattern):
                os.unlink(fglob)

        return formatted


def parallel_process(items, func):
    """Run a set of work items to completion
    """
    try:
        cpus = cpu_count()
    except NotImplementedError:
        cpus = 1

    task_queue = queue.Queue()

    # Use a list so that worker function will capture this variable
    pp_event = threading.Event()
    pp_result = [True]

    def worker():
        """Worker thread to process work items in parallel
        """
        while not pp_event.is_set():
            try:
                item = task_queue.get_nowait()
            except queue.Empty:
                # if the queue is empty, exit the worker thread
                pp_event.set()
                return

            try:
                ret = func(item)
            finally:
                # Tell the queue we finished with the item
                task_queue.task_done()

            # Return early if we fail, and signal we are done
            if not ret:
                # with pp_lock:
                #     pp_result[0] = False
                print("{} failed on item {}".format(func, item))

                # pp_event.set()
                return

    # Enqueue all the work we want to process
    for item in items:
        task_queue.put(item)

    # Process all the work
    threads = []
    for cpu in range(cpus):
        thread = threading.Thread(target=worker)

        thread.daemon = True
        thread.start()
        threads.append(thread)

    # Wait for the threads to finish
    # Loop with a timeout so that we can process Ctrl-C interrupts
    # Note: On Python 2.6 wait always returns None so we check is_set also,
    #  This works because we only set the event once, and never reset it
    while not pp_event.wait(1) and not pp_event.is_set():
        time.sleep(1)

    for thread in threads:
        thread.join()

    return pp_result[0]


def get_base_dir():
    """Get the base directory for mongo repo.
        This script assumes that it is running in buildscripts/, and uses
        that to find the base directory.
    """
    try:
        return subprocess.check_output(
            ['git', 'rev-parse', '--show-toplevel']).rstrip().decode('utf-8')
    except CalledProcessError:
        # We are not in a valid git directory. Use the script path instead.
        return os.path.dirname(os.path.dirname(os.path.realpath(__file__)))


def get_repos():
    """Get a list of Repos to check clang-format for
    """
    base_dir = get_base_dir()

    # Get a list of modules
    # GNU Radio is a single-git repo

    # paths = [os.path.join(base_dir, MODULE_DIR, m) for m in gnuradio_modules]

    paths = [base_dir]

    return [Repo(p) for p in paths]


class Repo(object):
    """Class encapsulates all knowledge about a git repository, and its metadata
        to run clang-format.
    """

    def __init__(self, path):
        self.path = path

        self.root = self._get_root()

    def _callgito(self, args):
        """Call git for this repository, and return the captured output
        """
        # These two flags are the equivalent of -C in newer versions of Git
        # but we use these to support versions pre 1.8.5 but it depends on the command
        # and what the current directory is
        return callo([
            'git', '--git-dir', os.path.join(self.path, ".git"), '--work-tree',
            self.path
        ] + args)

    def _callgit(self, args):
        """Call git for this repository without capturing output
        This is designed to be used when git returns non-zero exit codes.
        """
        # These two flags are the equivalent of -C in newer versions of Git
        # but we use these to support versions pre 1.8.5 but it depends on the command
        # and what the current directory is
        return subprocess.call([
            'git', '--git-dir', os.path.join(self.path, ".git"), '--work-tree',
            self.path
        ] + args)

    def _get_local_dir(self, path):
        """Get a directory path relative to the git root directory
        """
        if os.path.isabs(path):
            return os.path.relpath(path, self.root)
        return path

    def get_candidates(self, candidates):
        """Get the set of candidate files to check by querying the repository

        Returns the full path to the file for clang-format to consume.
        """
        if candidates is not None and len(candidates) > 0:
            candidates = [self._get_local_dir(f) for f in candidates]
            valid_files = list(
                set(candidates).intersection(self.get_candidate_files()))
        else:
            valid_files = list(self.get_candidate_files())

        # Get the full file name here
        valid_files = [
            os.path.normpath(os.path.join(self.root, f)) for f in valid_files
        ]

        return valid_files

    def get_root(self):
        """Get the root directory for this repository
        """
        return self.root

    def _get_root(self):
        """Gets the root directory for this repository from git
        """
        gito = self._callgito(['rev-parse', '--show-toplevel'])

        return gito.rstrip()

    def _git_ls_files(self, cmd):
        """Run git-ls-files and filter the list of files to a valid candidate list
        """
        gito = self._callgito(cmd)

        # This allows us to pick all the interesting files
        # in the mongo and mongo-enterprise repos
        file_list = [
            line.rstrip()
            for line in gito.splitlines()
            # TODO: exclude directories if needed
            # We don't want to lint volk
            if not "volk" in line
        ]

        file_list = [a for a in file_list if files_match.search(a)]

        return file_list

    def get_candidate_files(self):
        """Query git to get a list of all files in the repo to consider for analysis
        """
        return self._git_ls_files(["ls-files", "--cached"])

    def get_working_tree_candidate_files(self):
        """Query git to get a list of all files in the working tree to consider for analysis
        """
        return self._git_ls_files(["ls-files", "--cached", "--others"])

    def get_working_tree_candidates(self):
        """Get the set of candidate files to check by querying the repository

        Returns the full path to the file for clang-format to consume.
        """
        valid_files = list(self.get_working_tree_candidate_files())

        # Get the full file name here
        valid_files = [
            os.path.normpath(os.path.join(self.root, f)) for f in valid_files
        ]

        return valid_files

    def is_detached(self):
        """Is the current working tree in a detached HEAD state?
        """
        # symbolic-ref returns 1 if the repo is in a detached HEAD state
        return self._callgit(["symbolic-ref", "--quiet", "HEAD"])

    def is_ancestor(self, parent, child):
        """Is the specified parent hash an ancestor of child hash?
        """
        # merge base returns 0 if parent is an ancestor of child
        return not self._callgit(
            ["merge-base", "--is-ancestor", parent, child])

    def is_commit(self, sha1):
        """Is the specified hash a valid git commit?
        """
        # cat-file -e returns 0 if it is a valid hash
        return not self._callgit(["cat-file", "-e", "%s^{commit}" % sha1])

    def is_working_tree_dirty(self):
        """Does the current working tree have changes?
        """
        # diff returns 1 if the working tree has local changes
        return self._callgit(["diff", "--quiet"])

    def does_branch_exist(self, branch):
        """Does the branch exist?
        """
        # rev-parse returns 0 if the branch exists
        return not self._callgit(["rev-parse", "--verify", branch])

    def get_merge_base(self, commit):
        """Get the merge base between 'commit' and HEAD
        """
        return self._callgito(["merge-base", "HEAD", commit]).rstrip()

    def get_branch_name(self):
        """Get the current branch name, short form
           This returns "master", not "refs/head/master"
           Will not work if the current branch is detached
        """
        branch = self.rev_parse(["--abbrev-ref", "HEAD"])
        if branch == "HEAD":
            raise ValueError("Branch is currently detached")

        return branch

    def add(self, command):
        """git add wrapper
        """
        return self._callgito(["add"] + command)

    def checkout(self, command):
        """git checkout wrapper
        """
        return self._callgito(["checkout"] + command)

    def commit(self, command):
        """git commit wrapper
        """
        return self._callgito(["commit"] + command)

    def diff(self, command):
        """git diff wrapper
        """
        return self._callgito(["diff"] + command)

    def log(self, command):
        """git log wrapper
        """
        return self._callgito(["log"] + command)

    def rev_parse(self, command):
        """git rev-parse wrapper
        """
        return self._callgito(["rev-parse"] + command).rstrip()

    def rm(self, command):
        """git rm wrapper
        """
        return self._callgito(["rm"] + command)

    def show(self, command):
        """git show wrapper
        """
        return self._callgito(["show"] + command)


def get_list_from_lines(lines):
    """"Convert a string containing a series of lines into a list of strings
    """
    return [line.rstrip() for line in lines.splitlines()]


def get_files_to_check_working_tree():
    """Get a list of files to check form the working tree.
       This will pick up files not managed by git.
    """
    repos = get_repos()

    valid_files = list(
        itertools.chain.from_iterable(
            [r.get_working_tree_candidates() for r in repos]))
    return valid_files


def get_files_to_check():
    """Get a list of files that need to be checked
       based on which files are managed by git.
    """
    repos = get_repos()

    valid_files = list(
        itertools.chain.from_iterable([r.get_candidates(None) for r in repos]))

    return valid_files


def get_files_to_check_from_patch(patches):
    """
    Take a patch file generated by git diff,
    and scan the patch for a list of files to check.
    """
    candidates = []

    # Get a list of candidate_files
    check = re.compile(
        r"^diff --git a\/([a-z\/\.\-_0-9]+) b\/[a-z\/\.\-_0-9]+")

    candidates = []
    for patch in patches:
        if patch == "-":
            infile = sys.stdin
        else:
            infile = open(patch, "rb")
        candidates.extend([
            check.match(line).group(1) for line in infile.readlines()
            if check.match(line)
        ])
        infile.close()

    repos = get_repos()

    valid_files = list(
        itertools.chain.from_iterable(
            [r.get_candidates(candidates) for r in repos]))

    return valid_files


def _lint_files(clang_format, files):
    """Lint a list of files with clang-format
    """
    try:
        clang_format = ClangFormat(clang_format)
    except NameError as e:
        print(e)
        return False

    lint_clean = parallel_process([os.path.abspath(f) for f in files],
                                  clang_format.lint)

    if not lint_clean:
        print("ERROR: Code Style does not match coding style")
        sys.exit(1)


def lint(args):
    """Lint files command entry point
    """
    if args.patch and args.all:
        print("Only specify patch or all, but not both!")
        return False
    if args.patch:
        files = get_files_to_check_from_patch(args.patch)
    elif args.all:
        files = get_files_to_check_working_tree()
    else:
        files = get_files_to_check()

    if files:
        _lint_files(args.clang_format, files)

    return True


def _format_files(clang_format, files):
    """Format a list of files with clang-format
    """
    try:
        clang_format = ClangFormat(clang_format)
    except NameError as e:
        print(e)
        return (False)

    format_clean = parallel_process([os.path.abspath(f) for f in files],
                                    clang_format.format)

    if not format_clean:
        print("ERROR: failed to format files")
        sys.exit(1)


def _reformat_branch(clang_format, commit_prior_to_reformat,
                     commit_after_reformat):
    """Reformat a branch made before a clang-format run
    """
    try:
        clang_format = ClangFormat(clang_format)
    except NameError as e:
        print(e)
        return False

    if os.getcwd() != get_base_dir():
        raise ValueError("reformat-branch must be run from the repo root")

    repo = Repo(get_base_dir())

    # Validate that user passes valid commits
    if not repo.is_commit(commit_prior_to_reformat):
        raise ValueError(
            "Commit Prior to Reformat '%s' is not a valid commit in this repo"
            % commit_prior_to_reformat)

    if not repo.is_commit(commit_after_reformat):
        raise ValueError(
            "Commit After Reformat '%s' is not a valid commit in this repo" %
            commit_after_reformat)

    if not repo.is_ancestor(commit_prior_to_reformat, commit_after_reformat):
        raise ValueError((
            "Commit Prior to Reformat '%s' is not a valid ancestor of Commit After"
            + " Reformat '%s' in this repo") % (commit_prior_to_reformat,
                                                commit_after_reformat))

    # Validate the user is on a local branch that has the right merge base
    if repo.is_detached():
        raise ValueError(
            "You must not run this script in a detached HEAD state")

    # Validate the user has no pending changes
    if repo.is_working_tree_dirty():
        raise ValueError(
            "Your working tree has pending changes. You must have a clean working tree before proceeding."
        )

    merge_base = repo.get_merge_base(commit_prior_to_reformat)

    if not merge_base == commit_prior_to_reformat:
        raise ValueError(
            "Please rebase to '%s' and resolve all conflicts before running this script"
            % (commit_prior_to_reformat))

    # We assume the target branch is master, it could be a different branch if needed for testing
    merge_base = repo.get_merge_base("master")

    if not merge_base == commit_prior_to_reformat:
        raise ValueError(
            "This branch appears to already have advanced too far through the merge process"
        )

    # Everything looks good so lets start going through all the commits
    branch_name = repo.get_branch_name()
    new_branch = "%s-reformatted" % branch_name

    if repo.does_branch_exist(new_branch):
        raise ValueError(
            "The branch '%s' already exists. Please delete the branch '%s', or rename the current branch."
            % (new_branch, new_branch))

    commits = get_list_from_lines(
        repo.log([
            "--reverse", "--pretty=format:%H", "%s..HEAD" %
            commit_prior_to_reformat
        ]))

    previous_commit_base = commit_after_reformat

    # Go through all the commits the user made on the local branch and migrate to a new branch
    # that is based on post_reformat commits instead
    for commit_hash in commits:
        repo.checkout(["--quiet", commit_hash])

        deleted_files = []

        # Format each of the files by checking out just a single commit from the user's branch
        commit_files = get_list_from_lines(repo.diff(["HEAD~", "--name-only"]))

        for commit_file in commit_files:

            # Format each file needed if it was not deleted
            if not os.path.exists(commit_file):
                print(
                    "Skipping file '%s' since it has been deleted in commit '%s'"
                    % (commit_file, commit_hash))
                deleted_files.append(commit_file)
                continue

            if files_match.search(commit_file):
                clang_format.format(commit_file)
            else:
                print(
                    "Skipping file '%s' since it is not a file clang_format should format"
                    % commit_file)

        # Check if anything needed reformatting, and if so amend the commit
        if not repo.is_working_tree_dirty():
            print("Commit %s needed no reformatting" % commit_hash)
        else:
            repo.commit(["--all", "--amend", "--no-edit"])

        # Rebase our new commit on top the post-reformat commit
        previous_commit = repo.rev_parse(["HEAD"])

        # Checkout the new branch with the reformatted commits
        # Note: we will not name as a branch until we are done with all commits on the local branch
        repo.checkout(["--quiet", previous_commit_base])

        # Copy each file from the reformatted commit on top of the post reformat
        diff_files = get_list_from_lines(
            repo.diff([
                "%s~..%s" % (previous_commit, previous_commit), "--name-only"
            ]))

        for diff_file in diff_files:
            # If the file was deleted in the commit we are reformatting, we need to delete it again
            if diff_file in deleted_files:
                repo.rm([diff_file])
                continue

            if "volk" in diff_file:
                continue
            # The file has been added or modified, continue as normal
            file_contents = repo.show(["%s:%s" % (previous_commit, diff_file)])

            root_dir = os.path.dirname(diff_file)
            if root_dir and not os.path.exists(root_dir):
                os.makedirs(root_dir)

            with open(diff_file, "w+") as new_file:
                new_file.write(file_contents)

            repo.add([diff_file])

        # Create a new commit onto clang-formatted branch
        repo.commit(["--reuse-message=%s" % previous_commit])

        previous_commit_base = repo.rev_parse(["HEAD"])

    # Create a new branch to mark the hashes we have been using
    repo.checkout(["-b", new_branch])

    print("reformat-branch is done running.\n")
    print(
        "A copy of your branch has been made named '%s', and formatted with clang-format.\n"
        % new_branch)
    print("The original branch has been left unchanged.")
    print("The next step is to rebase the new branch on 'master'.")


def format_func(args):
    """Format files command entry point
    """
    if args.all and args.branch is not None:
        print("Only specify branch or all, but not both!")
        return False
    if not args.branch:
        if args.all:
            files = get_files_to_check_working_tree()
        else:
            files = get_files_to_check()
        _format_files(args.clang_format, files)
    else:
        _reformat_branch(args.clang_format, *args.branch)


def parse_args():
    """
    Parse commandline arguments
    """
    parser = ArgumentParser()
    parser.add_argument(
        "-c",
        "--clang-format",
        default="clang-format",
        help="clang-format binary")
    subparsers = parser.add_subparsers(help="clang-format action", dest="action")
    subparsers.required = True
    lint_parser = subparsers.add_parser(
        "lint", help="Lint-only (no modifications)")
    lint_parser.add_argument("-a", "--all", action="store_true")
    lint_parser.add_argument("-p", "--patch", help="patch to check")
    lint_parser.set_defaults(func=lint)

    format_parser = subparsers.add_parser(
        "format", help="Format files in place")
    format_parser.add_argument(
        "-b",
        "--branch",
        nargs=2,
        default=None,
        help="specify the commit hash before the format and after the format has been done"
    )
    format_parser.add_argument("-a", "--all", action="store_true")
    format_parser.set_defaults(func=format_func)
    return parser.parse_args()


def main():
    """Main entry point
    """
    args = parse_args()
    if hasattr(args, "func"):
        args.func(args)


if __name__ == "__main__":
    main()
