import copy
import logging
import os
import platform
import stat
import sys

import click

import gitlint
from gitlint import hooks
from gitlint.config import LintConfigBuilder, LintConfigError, LintConfigGenerator
from gitlint.deprecation import DEPRECATED_LOG_FORMAT
from gitlint.deprecation import LOG as DEPRECATED_LOG
from gitlint.exception import GitlintError
from gitlint.git import GitContext, GitContextError, git_version
from gitlint.lint import GitLinter
from gitlint.shell import shell
from gitlint.utils import LOG_FORMAT

# Error codes
GITLINT_SUCCESS = 0
MAX_VIOLATION_ERROR_CODE = 252
USAGE_ERROR_CODE = 253
GIT_CONTEXT_ERROR_CODE = 254
CONFIG_ERROR_CODE = 255

DEFAULT_CONFIG_FILE = ".gitlint"
# -n: disable swap files. This fixes a vim error on windows (E303: Unable to open swap file for <path>)
DEFAULT_COMMIT_MSG_EDITOR = "vim -n"

# Since we use the return code to denote the amount of errors, we need to change the default click usage error code
click.UsageError.exit_code = USAGE_ERROR_CODE

# We don't use logging.getLogger(__main__) here because that will cause DEBUG output to be lost
# when invoking gitlint as a python module (python -m gitlint.cli)
LOG = logging.getLogger("gitlint.cli")


class GitLintUsageError(GitlintError):
    """Exception indicating there is an issue with how gitlint is used."""


def setup_logging():
    """Setup gitlint logging"""

    # Root log, mostly used for debug
    root_log = logging.getLogger("gitlint")
    root_log.propagate = False  # Don't propagate to child loggers, the gitlint root logger handles everything
    root_log.setLevel(logging.WARN)
    handler = logging.StreamHandler()
    formatter = logging.Formatter(LOG_FORMAT)
    handler.setFormatter(formatter)
    root_log.addHandler(handler)

    # Deprecated log, to log deprecation warnings
    DEPRECATED_LOG.propagate = False  # Don't propagate to child logger
    DEPRECATED_LOG.setLevel(logging.WARNING)
    deprecated_log_handler = logging.StreamHandler()
    deprecated_log_handler.setFormatter(logging.Formatter(DEPRECATED_LOG_FORMAT))
    DEPRECATED_LOG.addHandler(deprecated_log_handler)


def log_system_info():
    LOG.debug("Platform: %s", platform.platform())
    LOG.debug("Python version: %s", sys.version)
    LOG.debug("Git version: %s", git_version())
    LOG.debug("Gitlint version: %s", gitlint.__version__)
    LOG.debug("GITLINT_USE_SH_LIB: %s", os.environ.get("GITLINT_USE_SH_LIB", "[NOT SET]"))
    LOG.debug("TERMINAL_ENCODING: %s", gitlint.utils.TERMINAL_ENCODING)
    LOG.debug("FILE_ENCODING: %s", gitlint.utils.FILE_ENCODING)


def build_config(
    target,
    config_path,
    c,
    extra_path,
    ignore,
    contrib,
    ignore_stdin,
    staged,
    fail_without_commits,
    verbose,
    silent,
    debug,
):
    """Creates a LintConfig object based on a set of commandline parameters."""
    config_builder = LintConfigBuilder()
    # Config precedence:
    # First, load default config or config from configfile
    if config_path:
        config_builder.set_from_config_file(config_path)
    elif os.path.exists(DEFAULT_CONFIG_FILE):
        config_builder.set_from_config_file(DEFAULT_CONFIG_FILE)

    # Then process any commandline configuration flags
    config_builder.set_config_from_string_list(c)

    # Finally, overwrite with any convenience commandline flags
    if ignore:
        config_builder.set_option("general", "ignore", ignore)

    if contrib:
        config_builder.set_option("general", "contrib", contrib)

    if ignore_stdin:
        config_builder.set_option("general", "ignore-stdin", ignore_stdin)

    if silent:
        config_builder.set_option("general", "verbosity", 0)
    elif verbose > 0:
        config_builder.set_option("general", "verbosity", verbose)

    if extra_path:
        config_builder.set_option("general", "extra-path", extra_path)

    if target:
        config_builder.set_option("general", "target", target)

    if debug:
        config_builder.set_option("general", "debug", debug)

    if staged:
        config_builder.set_option("general", "staged", staged)

    if fail_without_commits:
        config_builder.set_option("general", "fail-without-commits", fail_without_commits)

    config = config_builder.build()

    return config, config_builder


def get_stdin_data():
    """Helper function that returns data sent to stdin or False if nothing is sent"""
    # STDIN can only be 3 different types of things ("modes")
    #  1. An interactive terminal device (i.e. a TTY -> sys.stdin.isatty() or stat.S_ISCHR)
    #  2. A (named) pipe (stat.S_ISFIFO)
    #  3. A regular file (stat.S_ISREG)
    # Technically, STDIN can also be other device type like a named unix socket (stat.S_ISSOCK), but we don't
    # support that in gitlint (at least not today).
    #
    # Now, the behavior that we want is the following:
    # If someone sends something directly to gitlint via a pipe or a regular file, read it. If not, read from the
    # local repository.
    # Note that we don't care about whether STDIN is a TTY or not, we only care whether data is via a pipe or regular
    # file.
    # However, in case STDIN is not a TTY, it HAS to be one of the 2 other things (pipe or regular file), even if
    # no-one is actually sending anything to gitlint over them. In this case, we still want to read from the local
    # repository.
    # To support this use-case (which is common in CI runners such as Jenkins and Gitlab), we need to actually attempt
    # to read from STDIN in case it's a pipe or regular file. In case that fails, then we'll fall back to reading
    # from the local repo.

    mode = os.fstat(sys.stdin.fileno()).st_mode
    stdin_is_pipe_or_file = stat.S_ISFIFO(mode) or stat.S_ISREG(mode)
    if stdin_is_pipe_or_file:
        input_data = sys.stdin.read()
        # Only return the input data if there's actually something passed
        # i.e. don't consider empty piped data
        if input_data:
            return str(input_data)
    return False


def build_git_context(lint_config, msg_filename, commit_hash, refspec):
    """Builds a git context based on passed parameters and order of precedence"""

    # Determine which GitContext method to use if a custom message is passed
    from_commit_msg = GitContext.from_commit_msg
    if lint_config.staged:
        LOG.debug("Fetching additional meta-data from staged commit")

        def from_commit_msg(message):
            return GitContext.from_staged_commit(message, lint_config.target)

    # Order of precedence:
    # 1. Any data specified via --msg-filename
    if msg_filename:
        LOG.debug("Using --msg-filename.")
        return from_commit_msg(str(msg_filename.read()))

    # 2. Any data sent to stdin (unless stdin is being ignored)
    if not lint_config.ignore_stdin:
        stdin_input = get_stdin_data()
        if stdin_input:
            LOG.debug("Stdin data: '%s'", stdin_input)
            LOG.debug("Stdin detected and not ignored. Using as input.")
            return from_commit_msg(stdin_input)

    if lint_config.staged:
        raise GitLintUsageError(
            "The 'staged' option (--staged) can only be used when using '--msg-filename' or "
            "when piping data to gitlint via stdin."
        )

    # 3. Fallback to reading from local repository
    LOG.debug("No --msg-filename flag, no or empty data passed to stdin. Using the local repo.")

    if commit_hash and refspec:
        raise GitLintUsageError("--commit and --commits are mutually exclusive, use one or the other.")

    # 3.1 Linting a range of commits
    if refspec:
        # 3.1.1 Not real refspec, but comma-separated list of commit hashes
        if "," in refspec:
            commit_hashes = [hash.strip() for hash in refspec.split(",") if hash]
            return GitContext.from_local_repository(lint_config.target, commit_hashes=commit_hashes)
        # 3.1.2 Real refspec
        return GitContext.from_local_repository(lint_config.target, refspec=refspec)

    # 3.2 Linting a specific commit
    if commit_hash:
        return GitContext.from_local_repository(lint_config.target, commit_hashes=[commit_hash])

    # 3.3 Fallback to linting the current HEAD
    return GitContext.from_local_repository(lint_config.target)


def handle_gitlint_error(ctx, exc):
    """Helper function to handle exceptions"""
    if isinstance(exc, GitContextError):
        click.echo(exc)
        ctx.exit(GIT_CONTEXT_ERROR_CODE)
    elif isinstance(exc, GitLintUsageError):
        click.echo(f"Error: {exc}")
        ctx.exit(USAGE_ERROR_CODE)
    elif isinstance(exc, LintConfigError):
        click.echo(f"Config Error: {exc}")
        ctx.exit(CONFIG_ERROR_CODE)


class ContextObj:
    """Simple class to hold data that is passed between Click commands via the Click context."""

    def __init__(self, config, config_builder, commit_hash, refspec, msg_filename, gitcontext=None):
        self.config = config
        self.config_builder = config_builder
        self.commit_hash = commit_hash
        self.refspec = refspec
        self.msg_filename = msg_filename
        self.gitcontext = gitcontext


# fmt: off
@click.group(invoke_without_command=True, context_settings={"max_content_width": 120},
             epilog="When no COMMAND is specified, gitlint defaults to 'gitlint lint'.")
@click.option("--target", envvar="GITLINT_TARGET",
              type=click.Path(exists=True, resolve_path=True, file_okay=False, readable=True),
              help="Path of the target git repository. [default: current working directory]")
@click.option("-C", "--config", envvar="GITLINT_CONFIG",
              type=click.Path(exists=True, dir_okay=False, readable=True, resolve_path=True),
              help=f"Config file location [default: {DEFAULT_CONFIG_FILE}]")
@click.option("-c", multiple=True,
              help="Config flags in format <rule>.<option>=<value> (e.g.: -c T1.line-length=80). " +
                   "Flag can be used multiple times to set multiple config values.")
@click.option("--commit", envvar="GITLINT_COMMIT", default=None, help="Hash (SHA) of specific commit to lint.")
@click.option("--commits", envvar="GITLINT_COMMITS", default=None,
              help="The range of commits (refspec or comma-separated hashes) to lint. [default: HEAD]")
@click.option("-e", "--extra-path", envvar="GITLINT_EXTRA_PATH",
              help="Path to a directory or python module with extra user-defined rules",
              type=click.Path(exists=True, resolve_path=True, readable=True))
@click.option("--ignore", envvar="GITLINT_IGNORE", default="", help="Ignore rules (comma-separated by id or name).")
@click.option("--contrib", envvar="GITLINT_CONTRIB", default="",
              help="Contrib rules to enable (comma-separated by id or name).")
@click.option("--msg-filename", type=click.File(encoding=gitlint.utils.FILE_ENCODING),
              help="Path to a file containing a commit-msg.")
@click.option("--ignore-stdin", envvar="GITLINT_IGNORE_STDIN", is_flag=True,
              help="Ignore any stdin data. Useful for running in CI server.")
@click.option("--staged", envvar="GITLINT_STAGED", is_flag=True,
              help="Attempt smart guesses about meta info (like author name, email, branch, changed files, etc) " +
                   "for staged commits.")
@click.option("--fail-without-commits", envvar="GITLINT_FAIL_WITHOUT_COMMITS", is_flag=True,
              help="Hard fail when the target commit range is empty.")
@click.option("-v", "--verbose", envvar="GITLINT_VERBOSITY", count=True, default=0,
              help="Verbosity, use multiple times for more verbose output (e.g.: -v, -vv, -vvv). [default: -vvv]", )
@click.option("-s", "--silent", envvar="GITLINT_SILENT", is_flag=True,
              help="Silent mode (no output). Takes precedence over -v, -vv, -vvv.")
@click.option("-d", "--debug", envvar="GITLINT_DEBUG", help="Enable debugging output.", is_flag=True)
@click.version_option(version=gitlint.__version__)
@click.pass_context
def cli(
        ctx, target, config, c, commit, commits, extra_path, ignore, contrib,
        msg_filename, ignore_stdin, staged, fail_without_commits, verbose,
        silent, debug,
):
    """ Git lint tool, checks your git commit messages for styling issues

        Documentation: http://jorisroovers.github.io/gitlint
    """
    try:
        if debug:
            logging.getLogger("gitlint").setLevel(logging.DEBUG)
            DEPRECATED_LOG.setLevel(logging.DEBUG)
        LOG.debug("To report issues, please visit https://github.com/jorisroovers/gitlint/issues")

        log_system_info()

        # Get the lint config from the commandline parameters and
        # store it in the context (click allows storing an arbitrary object in ctx.obj).
        config, config_builder = build_config(target, config, c, extra_path, ignore, contrib, ignore_stdin,
                                              staged, fail_without_commits, verbose, silent, debug)
        LOG.debug("Configuration\n%s", config)

        ctx.obj = ContextObj(config, config_builder, commit, commits, msg_filename)

        # If no subcommand is specified, then just lint
        if ctx.invoked_subcommand is None:
            ctx.invoke(lint)

    except GitlintError as e:
        handle_gitlint_error(ctx, e)
# fmt: on


@cli.command("lint")
@click.pass_context
def lint(ctx):
    """Lints a git repository [default command]"""
    lint_config = ctx.obj.config
    refspec = ctx.obj.refspec
    commit_hash = ctx.obj.commit_hash
    msg_filename = ctx.obj.msg_filename

    gitcontext = build_git_context(lint_config, msg_filename, commit_hash, refspec)
    # Set gitcontext in the click context, so we can use it in command that are ran after this
    # in particular, this is used by run-hook
    ctx.obj.gitcontext = gitcontext

    number_of_commits = len(gitcontext.commits)
    # Exit if we don't have commits in the specified range. Use a 0 exit code, since a popular use-case is one
    # where users are using --commits in a check job to check the commit messages inside a CI job. By returning 0, we
    # ensure that these jobs don't fail if for whatever reason the specified commit range is empty.
    # This behavior can be overridden by using the --fail-without-commits flag.
    if number_of_commits == 0:
        LOG.debug('No commits in range "%s"', refspec)
        if lint_config.fail_without_commits:
            raise GitLintUsageError(f'No commits in range "{refspec}"')
        ctx.exit(GITLINT_SUCCESS)

    LOG.debug("Linting %d commit(s)", number_of_commits)
    general_config_builder = ctx.obj.config_builder
    last_commit = gitcontext.commits[-1]

    # Let's get linting!
    first_violation = True
    exit_code = GITLINT_SUCCESS
    for commit in gitcontext.commits:
        # Build a config_builder taking into account the commit specific config (if any)
        config_builder = general_config_builder.clone()
        config_builder.set_config_from_commit(commit)

        # Create a deepcopy from the original config, so we have a unique config object per commit
        # This is important for configuration rules to be able to modifying the config on a per commit basis
        commit_config = config_builder.build(copy.deepcopy(lint_config))

        # Actually do the linting
        linter = GitLinter(commit_config)
        violations = linter.lint(commit)
        # exit code equals the total number of violations in all commits
        exit_code += len(violations)
        if violations:
            # Display the commit hash & new lines intelligently
            if number_of_commits > 1 and commit.sha:
                commit_separator = "\n" if not first_violation or commit is last_commit else ""
                linter.display.e(f"{commit_separator}Commit {commit.sha[:10]}:")
            linter.print_violations(violations)
            first_violation = False

    # cap actual max exit code because bash doesn't like exit codes larger than 255:
    # http://tldp.org/LDP/abs/html/exitcodes.html
    exit_code = min(MAX_VIOLATION_ERROR_CODE, exit_code)
    LOG.debug("Exit Code = %s", exit_code)
    ctx.exit(exit_code)


@cli.command("install-hook")
@click.pass_context
def install_hook(ctx):
    """Install gitlint as a git commit-msg hook."""
    try:
        hooks.GitHookInstaller.install_commit_msg_hook(ctx.obj.config)
        hook_path = hooks.GitHookInstaller.commit_msg_hook_path(ctx.obj.config)
        click.echo(f"Successfully installed gitlint commit-msg hook in {hook_path}")
        ctx.exit(GITLINT_SUCCESS)
    except hooks.GitHookInstallerError as e:
        click.echo(e, err=True)
        ctx.exit(GIT_CONTEXT_ERROR_CODE)


@cli.command("uninstall-hook")
@click.pass_context
def uninstall_hook(ctx):
    """Uninstall gitlint commit-msg hook."""
    try:
        hooks.GitHookInstaller.uninstall_commit_msg_hook(ctx.obj.config)
        hook_path = hooks.GitHookInstaller.commit_msg_hook_path(ctx.obj.config)
        click.echo(f"Successfully uninstalled gitlint commit-msg hook from {hook_path}")
        ctx.exit(GITLINT_SUCCESS)
    except hooks.GitHookInstallerError as e:
        click.echo(e, err=True)
        ctx.exit(GIT_CONTEXT_ERROR_CODE)


@cli.command("run-hook")
@click.pass_context
def run_hook(ctx):
    """Runs the gitlint commit-msg hook."""

    exit_code = 1
    while exit_code > 0:
        try:
            click.echo("gitlint: checking commit message...")
            ctx.invoke(lint)
        except GitlintError as e:
            handle_gitlint_error(ctx, e)
        except click.exceptions.Exit as e:
            # Flush stderr andstdout, this resolves an issue with output ordering in Cygwin
            sys.stderr.flush()
            sys.stdout.flush()

            exit_code = e.exit_code
            if exit_code == GITLINT_SUCCESS:
                click.echo("gitlint: " + click.style("OK", fg="green") + " (no violations in commit message)")
                continue

            click.echo("-----------------------------------------------")
            click.echo("gitlint: " + click.style("Your commit message contains violations.", fg="red"))

            value = None
            while value not in ["y", "n", "e"]:
                click.echo(
                    "Continue with commit anyways (this keeps the current commit message)? [y(es)/n(no)/e(dit)] ",
                    nl=False,
                )

                # Ideally, we'd want to use click.getchar() or click.prompt() to get user's input here instead of
                # input(). However, those functions currently don't support getting answers from stdin.
                # This wouldn't be a huge issue since this is unlikely to occur in the real world,
                # were it not that we use a stdin to pipe answers into gitlint in our integration tests.
                # If that ever changes, we can revisit this.
                # Related click pointers:
                # - https://github.com/pallets/click/issues/1370
                # - https://github.com/pallets/click/pull/1372
                # - From https://click.palletsprojects.com/en/7.x/utils/#getting-characters-from-terminal
                #   Note that this function will always read from the terminal, even if stdin is instead a pipe.
                value = input()

            if value == "y":
                LOG.debug("run-hook: commit message accepted")
                exit_code = GITLINT_SUCCESS
            elif value == "e":
                LOG.debug("run-hook: editing commit message")
                msg_filename = ctx.obj.msg_filename
                if msg_filename:
                    msg_filename.seek(0)
                    editor = os.environ.get("EDITOR", DEFAULT_COMMIT_MSG_EDITOR)
                    msg_filename_path = os.path.realpath(msg_filename.name)
                    LOG.debug("run-hook: %s %s", editor, msg_filename_path)
                    shell(editor + " " + msg_filename_path)
                else:
                    click.echo("Editing only possible when --msg-filename is specified.")
                    ctx.exit(exit_code)
            elif value == "n":
                LOG.debug("run-hook: commit message declined")
                click.echo("Commit aborted.")
                click.echo("Your commit message: ")
                click.echo("-----------------------------------------------")
                click.echo(ctx.obj.gitcontext.commits[0].message.full)
                click.echo("-----------------------------------------------")
                ctx.exit(exit_code)

    ctx.exit(exit_code)


@cli.command("generate-config")
@click.pass_context
def generate_config(ctx):
    """Generates a sample gitlint config file."""
    path = click.prompt("Please specify a location for the sample gitlint config file", default=DEFAULT_CONFIG_FILE)
    path = os.path.realpath(path)
    dir_name = os.path.dirname(path)
    if not os.path.exists(dir_name):
        click.echo(f"Error: Directory '{dir_name}' does not exist.", err=True)
        ctx.exit(USAGE_ERROR_CODE)
    elif os.path.exists(path):
        click.echo(f'Error: File "{path}" already exists.', err=True)
        ctx.exit(USAGE_ERROR_CODE)

    LintConfigGenerator.generate_config(path)
    click.echo(f"Successfully generated {path}")
    ctx.exit(GITLINT_SUCCESS)


# Let's Party!
setup_logging()
if __name__ == "__main__":
    cli()  # pragma: no cover