from __future__ import annotations

import dataclasses
import logging
import os
import re
import shlex
import sys
import warnings
from collections.abc import Callable, Sequence
from datetime import date, datetime, timezone
from enum import Enum
from os.path import samefile
from pathlib import Path
from subprocess import CalledProcessError
from typing import TYPE_CHECKING

from .. import _discover as discover
from .. import _types as _t
from .._config import Configuration
from .._integration import data_from_mime
from .._run_cmd import CompletedProcess as _CompletedProcess
from .._run_cmd import require_command as _require_command
from .._run_cmd import run as _run
from .._scm_version import ScmVersion, meta, tag_to_version
from ._scm_workdir import Workdir, get_latest_file_mtime

if TYPE_CHECKING:
    from . import _hg_git as hg_git
log = logging.getLogger(__name__)

REF_TAG_RE = re.compile(r"(?<=\btag: )([^,]+)\b")
DESCRIBE_UNSUPPORTED = "%(describe"


# If testing command in shell make sure to quote the match argument like
# '*[0-9]*' as it will expand before being sent to git if there are any matching
# files in current directory.
def make_describe_command(match: str) -> list[str]:
    """Build a ``git describe`` command list restricted to tags matching *match*."""
    return [
        "git",
        "describe",
        "--dirty",
        "--tags",
        "--long",
        "--abbrev=40",
        "--match",
        match,
    ]


DEFAULT_DESCRIBE = make_describe_command("*[0-9]*")


class GitPreParse(Enum):
    """Available git pre-parse functions"""

    WARN_ON_SHALLOW = "warn_on_shallow"
    FAIL_ON_SHALLOW = "fail_on_shallow"
    FETCH_ON_SHALLOW = "fetch_on_shallow"
    FAIL_ON_MISSING_SUBMODULES = "fail_on_missing_submodules"


def run_git(
    args: Sequence[str | os.PathLike[str]],
    repo: Path,
    *,
    check: bool = False,
    timeout: int | None = None,
) -> _CompletedProcess:
    return _run(
        ["git", "--git-dir", repo / ".git", *args],
        cwd=repo,
        check=check,
        timeout=timeout,
    )


class GitWorkdir(Workdir):
    """experimental, may change at any time"""

    @classmethod
    def from_potential_worktree(cls, wd: _t.PathT) -> GitWorkdir | None:
        wd = Path(wd).resolve()
        real_wd = run_git(["rev-parse", "--show-prefix"], wd).parse_success(parse=str)
        if real_wd is None:
            return None
        else:
            real_wd = real_wd[:-1]  # remove the trailing pathsep

        if not real_wd:
            real_wd = os.fspath(wd)
        else:
            str_wd = os.fspath(wd)
            from .._compat import strip_path_suffix

            real_wd = strip_path_suffix(str_wd, real_wd)
        log.debug("real root %s", real_wd)
        if not samefile(real_wd, wd):
            return None

        return cls(Path(real_wd))

    def is_dirty(self) -> bool:
        return run_git(
            ["status", "--porcelain", "--untracked-files=no"], self.path
        ).parse_success(
            parse=bool,
            default=False,
        )

    def get_branch(self) -> str | None:
        return run_git(
            ["rev-parse", "--abbrev-ref", "HEAD"],
            self.path,
        ).parse_success(
            parse=str,
            error_msg="branch err (abbrev-err)",
        ) or run_git(
            ["symbolic-ref", "--short", "HEAD"],
            self.path,
        ).parse_success(
            parse=str,
            error_msg="branch err (symbolic-ref)",
        )

    def get_head_date(self) -> date | None:
        def parse_timestamp(timestamp_text: str) -> date | None:
            if "%c" in timestamp_text:
                log.warning("git too old -> timestamp is %r", timestamp_text)
                return None
            if sys.version_info < (3, 11) and timestamp_text.endswith("Z"):
                timestamp_text = timestamp_text[:-1] + "+00:00"

            # Convert to UTC to ensure consistent date regardless of local timezone
            dt = datetime.fromisoformat(timestamp_text)
            log.debug("dt: %s", dt)
            dt_utc = dt.astimezone(timezone.utc).date()
            log.debug("dt utc: %s", dt_utc)
            return dt_utc

        res = run_git(
            [
                *("-c", "log.showSignature=false"),
                *("log", "-n", "1", "HEAD"),
                "--format=%cI",
            ],
            self.path,
        )
        return res.parse_success(
            parse=parse_timestamp,
            error_msg="logging the iso date for head failed",
        )

    def get_dirty_tag_date(self) -> date | None:
        """Get the latest modification time of changed files in the working directory.

        Returns the date of the most recently modified file that has changes,
        or None if no files are changed or if an error occurs.
        """
        if not self.is_dirty():
            return None

        try:
            # Get list of changed files
            changed_files_res = run_git(["diff", "--name-only"], self.path)
            if changed_files_res.returncode != 0:
                return None

            changed_files = changed_files_res.stdout.strip().split("\n")
            return get_latest_file_mtime(changed_files, self.path)

        except Exception as e:
            log.debug("Failed to get dirty tag date: %s", e)
            return None

    def is_shallow(self) -> bool:
        return self.path.joinpath(".git/shallow").is_file()

    def head_is_exact_tag(self) -> bool:
        """True when HEAD points exactly at a tag (including lightweight tags)."""
        res = run_git(
            ["describe", "--exact-match", "--tags", "HEAD"],
            self.path,
        )
        return res.returncode == 0

    def fetch_shallow(self) -> None:
        try:
            run_git(
                ["fetch", "--unshallow", "--filter=blob:none"],
                self.path,
                check=True,
                timeout=240,
            )
        except CalledProcessError:
            run_git(["fetch", "--unshallow"], self.path, check=True, timeout=240)

    def node(self) -> str | None:
        return run_git(
            ["rev-parse", "--verify", "--quiet", "HEAD"], self.path
        ).parse_success(
            parse=str,
        )

    def count_all_nodes(self) -> int:
        res = run_git(["rev-list", "HEAD"], self.path)
        return res.stdout.count("\n") + 1

    def default_describe(self) -> _CompletedProcess:
        return run_git(DEFAULT_DESCRIBE[1:], self.path)


def warn_on_shallow(wd: GitWorkdir) -> None:
    """experimental, may change at any time"""
    if wd.is_shallow() and not wd.head_is_exact_tag():
        warnings.warn(f'"{wd.path}" is shallow and may cause errors', stacklevel=2)


def fetch_on_shallow(wd: GitWorkdir) -> None:
    """experimental, may change at any time"""
    if wd.is_shallow() and not wd.head_is_exact_tag():
        warnings.warn(
            f'"{wd.path}" was shallow, git fetch was used to rectify', stacklevel=2
        )
        wd.fetch_shallow()


def fail_on_shallow(wd: GitWorkdir) -> None:
    """experimental, may change at any time"""
    if wd.is_shallow() and not wd.head_is_exact_tag():
        raise ValueError(
            f'{wd.path} is shallow, please correct with "git fetch --unshallow"'
        )


def fail_on_missing_submodules(wd: GitWorkdir) -> None:
    """
    Fail if submodules are defined but not initialized/cloned.

    This pre_parse function checks if there are submodules defined in .gitmodules
    but not properly initialized (cloned). This helps prevent packaging incomplete
    projects when submodules are required for a complete build.
    """
    gitmodules_path = wd.path / ".gitmodules"
    if not gitmodules_path.exists():
        # No submodules defined, nothing to check
        return

    # Get submodule status - lines starting with '-' indicate uninitialized submodules
    status_result = run_git(["submodule", "status"], wd.path)
    if status_result.returncode != 0:
        # Command failed, might not be in a git repo or other error
        log.debug("Failed to check submodule status: %s", status_result.stderr)
        return

    status_lines = (
        status_result.stdout.strip().split("\n") if status_result.stdout.strip() else []
    )
    uninitialized_submodules = []

    for line in status_lines:
        line = line.strip()
        if line.startswith("-"):
            # Extract submodule path (everything after the commit hash)
            parts = line.split()
            if len(parts) >= 2:
                submodule_path = parts[1]
                uninitialized_submodules.append(submodule_path)

    # If .gitmodules exists but git submodule status returns nothing,
    # it means submodules are defined but not properly set up (common after cloning without --recurse-submodules)
    if not status_lines and gitmodules_path.exists():
        raise ValueError(
            f"Submodules are defined in .gitmodules but not initialized in {wd.path}. "
            f"Please run 'git submodule update --init --recursive' to initialize them."
        )

    if uninitialized_submodules:
        submodule_list = ", ".join(uninitialized_submodules)
        raise ValueError(
            f"Submodules are not initialized in {wd.path}: {submodule_list}. "
            f"Please run 'git submodule update --init --recursive' to initialize them."
        )


# Mapping from enum items to actual pre_parse functions
_GIT_PRE_PARSE_FUNCTIONS: dict[GitPreParse, Callable[[GitWorkdir], None]] = {
    GitPreParse.WARN_ON_SHALLOW: warn_on_shallow,
    GitPreParse.FAIL_ON_SHALLOW: fail_on_shallow,
    GitPreParse.FETCH_ON_SHALLOW: fetch_on_shallow,
    GitPreParse.FAIL_ON_MISSING_SUBMODULES: fail_on_missing_submodules,
}


def get_working_directory(config: Configuration, root: _t.PathT) -> GitWorkdir | None:
    """
    Return the working directory (``GitWorkdir``).
    """

    if config.parent:  # todo broken
        return GitWorkdir.from_potential_worktree(config.parent)

    for potential_root in discover.walk_potential_roots(
        root, search_parents=config.search_parent_directories
    ):
        potential_wd = GitWorkdir.from_potential_worktree(potential_root)
        if potential_wd is not None:
            return potential_wd

    return GitWorkdir.from_potential_worktree(root)


def parse(
    root: _t.PathT,
    config: Configuration,
    describe_command: str | list[str] | None = None,
    pre_parse: Callable[[GitWorkdir], None] | None = None,
) -> ScmVersion | None:
    """
    :param pre_parse: experimental pre_parse action, may change at any time.
                     Takes precedence over config.git_pre_parse if provided.
    """
    _require_command("git")
    wd = get_working_directory(config, root)
    if wd:
        # Use function parameter first, then config setting, then default
        if pre_parse is not None:
            effective_pre_parse = pre_parse
        else:
            # config.scm.git.pre_parse is always a GitPreParse enum instance
            effective_pre_parse = _GIT_PRE_PARSE_FUNCTIONS.get(
                config.scm.git.pre_parse, warn_on_shallow
            )

        return _git_parse_inner(
            config, wd, describe_command=describe_command, pre_parse=effective_pre_parse
        )
    else:
        return None


def version_from_describe(
    wd: GitWorkdir | hg_git.GitWorkdirHgClient,
    config: Configuration,
    describe_command: _t.CMD_TYPE | None,
) -> ScmVersion | None:
    if config.scm.git.describe_command is not None:
        describe_command = config.scm.git.describe_command

    if describe_command is not None:
        if isinstance(describe_command, str):
            describe_command = shlex.split(describe_command)
            # todo: figure how to ensure git with gitdir gets correctly invoked
        if describe_command[0] == "git":
            describe_res = run_git(describe_command[1:], wd.path)
        else:
            describe_res = _run(describe_command, wd.path)
    else:
        describe_res = wd.default_describe()

    def parse_describe(output: str) -> ScmVersion:
        tag, distance, node, dirty = _git_parse_describe(output)
        return meta(tag=tag, distance=distance, dirty=dirty, node=node, config=config)

    return describe_res.parse_success(parse=parse_describe)


def _git_parse_inner(
    config: Configuration,
    wd: GitWorkdir | hg_git.GitWorkdirHgClient,
    pre_parse: (Callable[[GitWorkdir | hg_git.GitWorkdirHgClient], None]) | None = None,
    describe_command: _t.CMD_TYPE | None = None,
) -> ScmVersion:
    if pre_parse:
        pre_parse(wd)

    version = version_from_describe(wd, config, describe_command)

    if version is None:
        # If 'git git_describe_command' failed, try to get the information otherwise.
        tag = config.version_cls(config.fallback_version or "0.0")
        node = wd.node()
        if node is None:
            distance = 0
            dirty = True
        else:
            distance = wd.count_all_nodes()
            node = "g" + node
            dirty = wd.is_dirty()
        version = meta(
            tag=tag, distance=distance, dirty=dirty, node=node, config=config
        )
    branch = wd.get_branch()
    node_date = wd.get_head_date()

    # If we can't get node_date from HEAD (e.g., no commits yet),
    # and the working directory is dirty, try to use the latest
    # modification time of changed files instead of current time
    if node_date is None and wd.is_dirty():
        dirty_date = wd.get_dirty_tag_date()
        if dirty_date is not None:
            node_date = dirty_date

    # Final fallback to current time
    if node_date is None:
        node_date = datetime.now(timezone.utc).date()

    return dataclasses.replace(version, branch=branch, node_date=node_date)


def _git_parse_describe(
    describe_output: str,
) -> tuple[str, int, str | None, bool]:
    # 'describe_output' looks e.g. like 'v1.5.0-0-g4060507' or
    # 'v1.15.1rc1-37-g9bd1298-dirty'.
    # It may also just be a bare tag name if this is a tagged commit and we are
    # parsing a .git_archival.txt file.

    if describe_output.endswith("-dirty"):
        dirty = True
        describe_output = describe_output[:-6]
    else:
        dirty = False

    split = describe_output.rsplit("-", 2)
    if len(split) < 3:  # probably a tagged commit
        tag = describe_output
        number = 0
        node = None
    else:
        tag, number_, node = split
        number = int(number_)
    return tag, number, node, dirty


def archival_to_version(
    data: dict[str, str], config: Configuration
) -> ScmVersion | None:
    node: str | None
    log.debug("data %s", data)
    archival_describe = data.get("describe-name", DESCRIBE_UNSUPPORTED)
    if DESCRIBE_UNSUPPORTED in archival_describe:
        warnings.warn("git archive did not support describe output", stacklevel=2)
    else:
        tag, number, node, _ = _git_parse_describe(archival_describe)
        return meta(
            tag,
            config=config,
            distance=number,
            node=node,
        )

    for ref in REF_TAG_RE.findall(data.get("ref-names", "")):
        version = tag_to_version(ref, config)
        if version is not None:
            return meta(version, config=config)
    node = data.get("node")
    if node is None:
        return None
    elif "$FORMAT" in node.upper():
        warnings.warn(
            "unprocessed git archival found (no export subst applied)", stacklevel=2
        )
        return None
    else:
        return meta("0.0", node=node, config=config)


def parse_archival(root: _t.PathT, config: Configuration) -> ScmVersion | None:
    archival = os.path.join(root, ".git_archival.txt")
    data = data_from_mime(archival)
    return archival_to_version(data, config=config)
