# Copyright (C) 2008 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import functools
import json
import os
import re
import subprocess
import sys
from typing import Any, Optional

import error
from git_trace2_event_log_base import BaseEventLog
import platform_utils
import repo_logging
import repo_trace
from wrapper import Wrapper


GIT = "git"
GIT_DIR = "GIT_DIR"

LAST_GITDIR = None
LAST_CWD = None
DEFAULT_GIT_FAIL_MESSAGE = "git command failure"
ERROR_EVENT_LOGGING_PREFIX = "RepoGitCommandError"
# Common line length limit
GIT_ERROR_STDOUT_LINES = 1
GIT_ERROR_STDERR_LINES = 10
INVALID_GIT_EXIT_CODE = 126

logger = repo_logging.RepoLogger(__file__)


class _GitCall:
    @functools.lru_cache(maxsize=None)  # noqa: B019
    def version_tuple(self):
        ret = Wrapper().ParseGitVersion()
        if ret is None:
            msg = "fatal: unable to detect git version"
            logger.error(msg)
            raise GitRequireError(msg)
        return ret

    def __getattr__(self, name):
        name = name.replace("_", "-")

        def fun(*cmdv):
            command = [name]
            command.extend(cmdv)
            return GitCommand(None, command, add_event_log=False).Wait() == 0

        return fun


git = _GitCall()


def IsValidBranchName(name: str) -> bool:
    """Return whether |name| is valid where Git expects a branch name."""
    p = GitCommand(
        None,
        ["check-ref-format", "--branch", name],
        capture_stdout=True,
        capture_stderr=True,
        add_event_log=False,
        log_as_error=False,
    )
    return p.Wait() == 0


def RepoSourceVersion():
    """Return the version of the repo.git tree."""
    ver = getattr(RepoSourceVersion, "version", None)

    # We avoid GitCommand so we don't run into circular deps -- GitCommand needs
    # to initialize version info we provide.
    if ver is None:
        env = GitCommand._GetBasicEnv()

        proj = os.path.dirname(os.path.abspath(__file__))
        env[GIT_DIR] = os.path.join(proj, ".git")
        result = subprocess.run(
            [GIT, "describe", "HEAD"],
            stdout=subprocess.PIPE,
            stderr=subprocess.DEVNULL,
            encoding="utf-8",
            env=env,
            check=False,
        )
        if result.returncode == 0:
            ver = result.stdout.strip()
            if ver.startswith("v"):
                ver = ver[1:]
        else:
            ver = "unknown"
        RepoSourceVersion.version = ver

    return ver


@functools.lru_cache(maxsize=None)
def GetEventTargetPath():
    """Get the 'trace2.eventtarget' path from git configuration.

    Returns:
        path: git config's 'trace2.eventtarget' path if it exists, or None
    """
    path = None
    cmd = ["config", "--get", "trace2.eventtarget"]
    # TODO(https://crbug.com/gerrit/13706): Use GitConfig when it supports
    # system git config variables.
    p = GitCommand(
        None,
        cmd,
        capture_stdout=True,
        capture_stderr=True,
        bare=True,
        add_event_log=False,
    )
    retval = p.Wait()
    if retval == 0:
        # Strip trailing carriage-return in path.
        path = p.stdout.rstrip("\n")
        if path == "":
            return None
    elif retval != 1:
        # `git config --get` is documented to produce an exit status of `1`
        # if the requested variable is not present in the configuration.
        # Report any other return value as an error.
        logger.error(
            "repo: error: 'git config --get' call failed with return code: "
            "%r, stderr: %r",
            retval,
            p.stderr,
        )
    return path


class UserAgent:
    """Mange User-Agent settings when talking to external services

    We follow the style as documented here:
    https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/User-Agent
    """

    _os = None
    _repo_ua = None
    _git_ua = None

    @property
    def os(self):
        """The operating system name."""
        if self._os is None:
            os_name = sys.platform
            if os_name.lower().startswith("linux"):
                os_name = "Linux"
            elif os_name == "win32":
                os_name = "Win32"
            elif os_name == "cygwin":
                os_name = "Cygwin"
            elif os_name == "darwin":
                os_name = "Darwin"
            self._os = os_name

        return self._os

    @property
    def repo(self):
        """The UA when connecting directly from repo."""
        if self._repo_ua is None:
            py_version = sys.version_info
            self._repo_ua = "git-repo/%s (%s) git/%s Python/%d.%d.%d" % (
                RepoSourceVersion(),
                self.os,
                git.version_tuple().full,
                py_version.major,
                py_version.minor,
                py_version.micro,
            )

        return self._repo_ua

    @property
    def git(self):
        """The UA when running git."""
        if self._git_ua is None:
            self._git_ua = (
                f"git/{git.version_tuple().full} ({self.os}) "
                f"git-repo/{RepoSourceVersion()}"
            )
        return self._git_ua


user_agent = UserAgent()


def git_require(min_version, fail=False, msg=""):
    git_version = git.version_tuple()
    if min_version <= git_version:
        return True
    if fail:
        need = ".".join(map(str, min_version))
        if msg:
            msg = " for " + msg
        error_msg = f"fatal: git {need} or later required{msg}"
        logger.error(error_msg)
        raise GitRequireError(error_msg)
    return False


def _build_env(
    _kwargs_only=(),
    bare: Optional[bool] = False,
    disable_editor: Optional[bool] = False,
    ssh_proxy: Optional[Any] = None,
    gitdir: Optional[str] = None,
    objdir: Optional[str] = None,
):
    """Constucts an env dict for command execution."""

    assert _kwargs_only == (), "_build_env only accepts keyword arguments."

    env = GitCommand._GetBasicEnv()

    if disable_editor:
        env["GIT_EDITOR"] = ":"
    if ssh_proxy:
        env["REPO_SSH_SOCK"] = ssh_proxy.sock()
        env["GIT_SSH"] = ssh_proxy.proxy
        env["GIT_SSH_VARIANT"] = "ssh"
    if "http_proxy" in env and "darwin" == sys.platform:
        s = f"'http.proxy={env['http_proxy']}'"
        p = env.get("GIT_CONFIG_PARAMETERS")
        if p is not None:
            s = p + " " + s
        env["GIT_CONFIG_PARAMETERS"] = s
    if "GIT_ALLOW_PROTOCOL" not in env:
        env["GIT_ALLOW_PROTOCOL"] = (
            "file:git:http:https:ssh:persistent-http:persistent-https:sso:rpc"
        )
    env["GIT_HTTP_USER_AGENT"] = user_agent.git

    if objdir:
        # Set to the place we want to save the objects.
        env["GIT_OBJECT_DIRECTORY"] = objdir

        alt_objects = os.path.join(gitdir, "objects") if gitdir else None
        if alt_objects and os.path.realpath(alt_objects) != os.path.realpath(
            objdir
        ):
            # Allow git to search the original place in case of local or unique
            # refs that git will attempt to resolve even if we aren't fetching
            # them.
            env["GIT_ALTERNATE_OBJECT_DIRECTORIES"] = alt_objects
    if bare and gitdir is not None:
        env[GIT_DIR] = gitdir

    return env


class GitCommand:
    """Wrapper around a single git invocation."""

    def __init__(
        self,
        project,
        cmdv,
        bare=False,
        input=None,
        capture_stdout=False,
        capture_stdout_bytes: bool = False,
        capture_stderr=False,
        merge_output=False,
        disable_editor=False,
        ssh_proxy=None,
        cwd=None,
        gitdir=None,
        objdir=None,
        verify_command=False,
        add_event_log=True,
        log_as_error=True,
    ):
        if project:
            if not cwd:
                cwd = project.worktree
            if not gitdir:
                gitdir = project.gitdir

        self.project = project
        self.cmdv = cmdv
        self.verify_command = verify_command
        self.stdout, self.stderr = None, None
        if capture_stdout_bytes:
            if merge_output:
                raise ValueError(
                    "capture_stdout_bytes cannot be combined with merge_output"
                )
            capture_stdout = True

        # Git on Windows wants its paths only using / for reliability.
        if platform_utils.isWindows():
            if objdir:
                objdir = objdir.replace("\\", "/")
            if gitdir:
                gitdir = gitdir.replace("\\", "/")

        env = _build_env(
            disable_editor=disable_editor,
            ssh_proxy=ssh_proxy,
            objdir=objdir,
            gitdir=gitdir,
            bare=bare,
        )

        command = [GIT]
        if bare:
            cwd = None
        command_name = cmdv[0]
        command.append(command_name)

        if command_name in ("fetch", "clone"):
            env["GIT_TERMINAL_PROMPT"] = "0"
        if command_name in ("fetch", "clone", "push"):
            # Need to use the --progress flag for fetch/clone/push so output
            # will be displayed as by default git only does progress output if
            # stderr is a TTY.
            if sys.stderr.isatty():
                if (
                    "--progress" not in cmdv
                    and "--no-progress" not in cmdv
                    and "--quiet" not in cmdv
                    and "-q" not in cmdv
                ):
                    command.append("--progress")
        command.extend(cmdv[1:])

        event_log = (
            BaseEventLog(env=env, add_init_count=True)
            if add_event_log
            else None
        )

        try:
            self._RunCommand(
                command,
                env,
                capture_stdout=capture_stdout,
                capture_stdout_bytes=capture_stdout_bytes,
                capture_stderr=capture_stderr,
                merge_output=merge_output,
                ssh_proxy=ssh_proxy,
                cwd=cwd,
                input=input,
            )
            self.VerifyCommand()
        except GitCommandError as e:
            if event_log is not None:
                error_info = json.dumps(
                    {
                        "ErrorType": type(e).__name__,
                        "Project": e.project,
                        "CommandName": command_name,
                        "Message": str(e),
                        "ReturnCode": (
                            str(e.git_rc) if e.git_rc is not None else None
                        ),
                        "IsError": log_as_error,
                    }
                )
                event_log.ErrorEvent(
                    f"{ERROR_EVENT_LOGGING_PREFIX}:{error_info}"
                )
                event_log.Write(GetEventTargetPath())
            if isinstance(e, GitPopenCommandError):
                raise

    def _RunCommand(
        self,
        command,
        env,
        capture_stdout=False,
        capture_stdout_bytes: bool = False,
        capture_stderr=False,
        merge_output=False,
        ssh_proxy=None,
        cwd=None,
        input=None,
    ):
        # Set subprocess.PIPE for streams that need to be captured.
        stdin = subprocess.PIPE if input else None
        stdout = subprocess.PIPE if capture_stdout else None
        stderr = (
            subprocess.STDOUT
            if merge_output
            else (subprocess.PIPE if capture_stderr else None)
        )

        # tee_stderr acts like a tee command for stderr, in that, it captures
        # stderr from the subprocess and streams it back to sys.stderr, while
        # keeping a copy in-memory.
        # This allows us to store stderr logs from the subprocess into
        # GitCommandError.
        # Certain git operations, such as `git push`, writes diagnostic logs,
        # such as, progress bar for pushing, into stderr. To ensure we don't
        # break git's UX, we need to write to sys.stderr as we read from the
        # subprocess. Setting encoding or errors makes subprocess return
        # io.TextIOWrapper, which is line buffered. To avoid line-buffering
        # while tee-ing stderr, we unset these kwargs. See GitCommand._Tee
        # for tee-ing between the streams.
        # We tee stderr iff the caller doesn't want to capture any stream to
        # not disrupt the existing flow.
        # See go/tee-repo-stderr for more context.
        tee_stderr = False
        kwargs = {"encoding": "utf-8", "errors": "backslashreplace"}
        if capture_stdout_bytes:
            kwargs = {}
            if isinstance(input, str):
                input = input.encode("utf-8", "surrogateescape")
        if not (stdin or stdout or stderr):
            tee_stderr = True
            # stderr will be written back to sys.stderr even though it is
            # piped here.
            stderr = subprocess.PIPE
            kwargs = {}

        dbg = ""
        if repo_trace.IsTrace():
            global LAST_CWD
            global LAST_GITDIR

            if cwd and LAST_CWD != cwd:
                if LAST_GITDIR or LAST_CWD:
                    dbg += "\n"
                dbg += ": cd %s\n" % cwd
                LAST_CWD = cwd

            if GIT_DIR in env and LAST_GITDIR != env[GIT_DIR]:
                if LAST_GITDIR or LAST_CWD:
                    dbg += "\n"
                dbg += ": export GIT_DIR=%s\n" % env[GIT_DIR]
                LAST_GITDIR = env[GIT_DIR]

            if "GIT_OBJECT_DIRECTORY" in env:
                dbg += (
                    ": export GIT_OBJECT_DIRECTORY=%s\n"
                    % env["GIT_OBJECT_DIRECTORY"]
                )
            if "GIT_ALTERNATE_OBJECT_DIRECTORIES" in env:
                dbg += ": export GIT_ALTERNATE_OBJECT_DIRECTORIES=%s\n" % (
                    env["GIT_ALTERNATE_OBJECT_DIRECTORIES"]
                )

            dbg += ": "
            dbg += " ".join(command)
            if stdin == subprocess.PIPE:
                dbg += " 0<|"
            if stdout == subprocess.PIPE:
                dbg += " 1>|"
            if stderr == subprocess.PIPE:
                dbg += " 2>|"
            elif stderr == subprocess.STDOUT:
                dbg += " 2>&1"

        with repo_trace.Trace(
            "git command %s %s with debug: %s", LAST_GITDIR, command, dbg
        ):
            try:
                p = subprocess.Popen(
                    command,
                    cwd=cwd,
                    env=env,
                    stdin=stdin,
                    stdout=stdout,
                    stderr=stderr,
                    **kwargs,
                )
            except Exception as e:
                raise GitPopenCommandError(
                    message=f"{command[1]}: {e}",
                    project=self.project.name if self.project else None,
                    command_args=self.cmdv,
                )

            if ssh_proxy:
                ssh_proxy.add_client(p)

            self.process = p

            try:
                if tee_stderr:
                    # tee_stderr streams stderr to sys.stderr while capturing
                    # a copy within self.stderr. tee_stderr is only enabled
                    # when the caller wants to pipe no stream.
                    self.stderr = self._Tee(p.stderr, sys.stderr)
                else:
                    self.stdout, self.stderr = p.communicate(input=input)
                    if capture_stdout_bytes and isinstance(self.stderr, bytes):
                        self.stderr = self.stderr.decode(
                            "utf-8", "backslashreplace"
                        ).replace("\r\n", "\n")
            finally:
                if ssh_proxy:
                    ssh_proxy.remove_client(p)
            self.rc = p.wait()

    @staticmethod
    def _Tee(in_stream, out_stream):
        """Writes text from in_stream to out_stream while recording in buffer.

        Args:
            in_stream: I/O stream to be read from.
            out_stream: I/O stream to write to.

        Returns:
            A str containing everything read from the in_stream.
        """
        buffer = ""
        read_size = 1024 if sys.version_info < (3, 7) else -1
        chunk = in_stream.read1(read_size)
        while chunk:
            # Convert to str.
            if not hasattr(chunk, "encode"):
                chunk = chunk.decode("utf-8", "backslashreplace")

            buffer += chunk
            out_stream.write(chunk)
            out_stream.flush()

            chunk = in_stream.read1(read_size)

        return buffer

    @staticmethod
    def _GetBasicEnv():
        """Return a basic env for running git under.

        This is guaranteed to be side-effect free.
        """
        env = os.environ.copy()
        for key in (
            repo_trace.REPO_TRACE,
            GIT_DIR,
            "GIT_ALTERNATE_OBJECT_DIRECTORIES",
            "GIT_OBJECT_DIRECTORY",
            "GIT_WORK_TREE",
            "GIT_GRAFT_FILE",
            "GIT_INDEX_FILE",
        ):
            env.pop(key, None)
        return env

    def VerifyCommand(self) -> None:
        if self.rc == 0:
            return None
        raw_stdout = self.stdout
        if isinstance(raw_stdout, bytes):
            first_records = re.split(
                rb"\r\n|[\r\n\0]", raw_stdout, maxsplit=GIT_ERROR_STDOUT_LINES
            )[:GIT_ERROR_STDOUT_LINES]
            stdout = (
                "\n".join(
                    r.decode("utf-8", "backslashreplace") for r in first_records
                )
                if raw_stdout
                else None
            )
        elif raw_stdout:
            first_records = re.split(
                r"\r\n|[\r\n\0]", raw_stdout, maxsplit=GIT_ERROR_STDOUT_LINES
            )[:GIT_ERROR_STDOUT_LINES]
            stdout = "\n".join(first_records)
        else:
            stdout = None

        raw_stderr = self.stderr
        if isinstance(raw_stderr, bytes):
            raw_stderr = raw_stderr.decode("utf-8", "backslashreplace")
        stderr = (
            "\n".join(raw_stderr.split("\n")[:GIT_ERROR_STDERR_LINES])
            if raw_stderr
            else None
        )
        project = self.project.name if self.project else None
        raise GitCommandError(
            project=project,
            command_args=self.cmdv,
            git_rc=self.rc,
            git_stdout=stdout,
            git_stderr=stderr,
        )

    def Wait(self):
        if self.verify_command:
            self.VerifyCommand()
        return self.rc


class GitRequireError(error.RepoExitError):
    """Error raised when git version is unavailable or invalid."""

    def __init__(self, message, exit_code: int = INVALID_GIT_EXIT_CODE):
        super().__init__(message, exit_code=exit_code)


class GitCommandError(error.GitError):
    """
    Error raised from a failed git command.
    Note that GitError can refer to any Git related error (e.g. branch not
    specified for project.py 'UploadForReview'), while GitCommandError is
    raised exclusively from non-zero exit codes returned from git commands.
    """

    # Tuples with error formats and suggestions for those errors.
    _ERROR_TO_SUGGESTION = [
        (
            re.compile("couldn't find remote ref .*"),
            "Check if the provided ref exists in the remote.",
        ),
        (
            re.compile("unable to access '.*': .*"),
            (
                "Please make sure you have the correct access rights and the "
                "repository exists."
            ),
        ),
        (
            re.compile("'.*' does not appear to be a git repository"),
            "Are you running this repo command outside of a repo workspace?",
        ),
        (
            re.compile("not a git repository"),
            "Are you running this repo command outside of a repo workspace?",
        ),
    ]

    def __init__(
        self,
        message: str = DEFAULT_GIT_FAIL_MESSAGE,
        git_rc: int = None,
        git_stdout: str = None,
        git_stderr: str = None,
        **kwargs,
    ):
        super().__init__(
            message,
            **kwargs,
        )
        self.git_rc = git_rc
        self.git_stdout = git_stdout
        self.git_stderr = git_stderr

    @property
    @functools.lru_cache(maxsize=None)  # noqa: B019
    def suggestion(self):
        """Returns helpful next steps for the given stderr."""
        if not self.git_stderr:
            return self.git_stderr

        for err, suggestion in self._ERROR_TO_SUGGESTION:
            if err.search(self.git_stderr):
                return suggestion

        return None

    def __str__(self):
        args = "[]" if not self.command_args else " ".join(self.command_args)
        error_type = type(self).__name__
        string = f"{error_type}: '{args}' on {self.project} failed"

        if self.message != DEFAULT_GIT_FAIL_MESSAGE:
            string += f": {self.message}"

        if self.git_stdout:
            string += f"\nstdout: {self.git_stdout}"

        if self.git_stderr:
            string += f"\nstderr: {self.git_stderr}"

        if self.suggestion:
            string += f"\nsuggestion: {self.suggestion}"

        return string


class GitPopenCommandError(error.GitError):
    """
    Error raised when subprocess.Popen fails for a GitCommand
    """