"""Utility code for facilitating collection of code coverage when running tests."""
from __future__ import annotations

import atexit
import dataclasses
import os
import sqlite3
import tempfile
import typing as t

from .config import (
    IntegrationConfig,
    SanityConfig,
    TestConfig,
)

from .io import (
    write_text_file,
    make_dirs,
    open_binary_file,
)

from .util import (
    ApplicationError,
    InternalError,
    COVERAGE_CONFIG_NAME,
    remove_tree,
    sanitize_host_name,
    str_to_version,
)

from .data import (
    data_context,
)

from .util_common import (
    intercept_python,
    ResultType,
)

from .host_configs import (
    DockerConfig,
    HostConfig,
    OriginConfig,
    PosixRemoteConfig,
    PosixSshConfig,
    PythonConfig,
)

from .constants import (
    SUPPORTED_PYTHON_VERSIONS,
    CONTROLLER_PYTHON_VERSIONS,
)

from .thread import (
    mutex,
)


@dataclasses.dataclass(frozen=True)
class CoverageVersion:
    """Details about a coverage version and its supported Python versions."""
    coverage_version: str
    schema_version: int
    min_python: tuple[int, int]
    max_python: tuple[int, int]


COVERAGE_VERSIONS = (
    # IMPORTANT: Keep this in sync with the ansible-test.txt requirements file.
    CoverageVersion('6.5.0', 7, (3, 7), (3, 11)),
    CoverageVersion('4.5.4', 0, (2, 6), (3, 6)),
)
"""
This tuple specifies the coverage version to use for Python version ranges.
"""

CONTROLLER_COVERAGE_VERSION = COVERAGE_VERSIONS[0]
"""The coverage version supported on the controller."""


class CoverageError(ApplicationError):
    """Exception caused while attempting to read a coverage file."""
    def __init__(self, path: str, message: str) -> None:
        self.path = path
        self.message = message

        super().__init__(f'Error reading coverage file "{os.path.relpath(path)}": {message}')


def get_coverage_version(version: str) -> CoverageVersion:
    """Return the coverage version to use with the specified Python version."""
    python_version = str_to_version(version)
    supported_versions = [entry for entry in COVERAGE_VERSIONS if entry.min_python <= python_version <= entry.max_python]

    if not supported_versions:
        raise InternalError(f'Python {version} has no matching entry in COVERAGE_VERSIONS.')

    if len(supported_versions) > 1:
        raise InternalError(f'Python {version} has multiple matching entries in COVERAGE_VERSIONS.')

    coverage_version = supported_versions[0]

    return coverage_version


def get_coverage_file_schema_version(path: str) -> int:
    """
    Return the schema version from the specified coverage file.
    SQLite based files report schema version 1 or later.
    JSON based files are reported as schema version 0.
    An exception is raised if the file is not recognized or the schema version cannot be determined.
    """
    with open_binary_file(path) as file_obj:
        header = file_obj.read(16)

    if header.startswith(b'!coverage.py: '):
        return 0

    if header.startswith(b'SQLite'):
        return get_sqlite_schema_version(path)

    raise CoverageError(path, f'Unknown header: {header!r}')


def get_sqlite_schema_version(path: str) -> int:
    """Return the schema version from a SQLite based coverage file."""
    try:
        with sqlite3.connect(path) as connection:
            cursor = connection.cursor()
            cursor.execute('select version from coverage_schema')
            schema_version = cursor.fetchmany(1)[0][0]
    except Exception as ex:
        raise CoverageError(path, f'SQLite error: {ex}') from ex

    if not isinstance(schema_version, int):
        raise CoverageError(path, f'Schema version is {type(schema_version)} instead of {int}: {schema_version}')

    if schema_version < 1:
        raise CoverageError(path, f'Schema version is out-of-range: {schema_version}')

    return schema_version


def cover_python(
    args: TestConfig,
    python: PythonConfig,
    cmd: list[str],
    target_name: str,
    env: dict[str, str],
    capture: bool,
    data: t.Optional[str] = None,
    cwd: t.Optional[str] = None,
) -> tuple[t.Optional[str], t.Optional[str]]:
    """Run a command while collecting Python code coverage."""
    if args.coverage:
        env.update(get_coverage_environment(args, target_name, python.version))

    return intercept_python(args, python, cmd, env, capture, data, cwd)


def get_coverage_platform(config: HostConfig) -> str:
    """Return the platform label for the given host config."""
    if isinstance(config, PosixRemoteConfig):
        platform = f'remote-{sanitize_host_name(config.name)}'
    elif isinstance(config, DockerConfig):
        platform = f'docker-{sanitize_host_name(config.name)}'
    elif isinstance(config, PosixSshConfig):
        platform = f'ssh-{sanitize_host_name(config.host)}'
    elif isinstance(config, OriginConfig):
        platform = 'origin'  # previous versions of ansible-test used "local-{python_version}"
    else:
        raise NotImplementedError(f'Coverage platform label not defined for type: {type(config)}')

    return platform


def get_coverage_environment(
    args: TestConfig,
    target_name: str,
    version: str,
) -> dict[str, str]:
    """Return environment variables needed to collect code coverage."""
    # unit tests, sanity tests and other special cases (localhost only)
    # config is in a temporary directory
    # results are in the source tree
    config_file = get_coverage_config(args)
    coverage_name = '='.join((args.command, target_name, get_coverage_platform(args.controller), f'python-{version}', 'coverage'))
    coverage_dir = os.path.join(data_context().content.root, data_context().content.results_path, ResultType.COVERAGE.name)
    coverage_file = os.path.join(coverage_dir, coverage_name)

    make_dirs(coverage_dir)

    if args.coverage_check:
        # cause the 'coverage' module to be found, but not imported or enabled
        coverage_file = ''

    # Enable code coverage collection on local Python programs (this does not include Ansible modules).
    # Used by the injectors to support code coverage.
    # Used by the pytest unit test plugin to support code coverage.
    # The COVERAGE_FILE variable is also used directly by the 'coverage' module.
    env = dict(
        COVERAGE_CONF=config_file,
        COVERAGE_FILE=coverage_file,
    )

    return env


@mutex
def get_coverage_config(args: TestConfig) -> str:
    """Return the path to the coverage config, creating the config if it does not already exist."""
    try:
        return get_coverage_config.path  # type: ignore[attr-defined]
    except AttributeError:
        pass

    coverage_config = generate_coverage_config(args)

    if args.explain:
        temp_dir = '/tmp/coverage-temp-dir'
    else:
        temp_dir = tempfile.mkdtemp()
        atexit.register(lambda: remove_tree(temp_dir))

    path = os.path.join(temp_dir, COVERAGE_CONFIG_NAME)

    if not args.explain:
        write_text_file(path, coverage_config)

    get_coverage_config.path = path  # type: ignore[attr-defined]

    return path


def generate_coverage_config(args: TestConfig) -> str:
    """Generate code coverage configuration for tests."""
    if data_context().content.collection:
        coverage_config = generate_collection_coverage_config(args)
    else:
        coverage_config = generate_ansible_coverage_config()

    return coverage_config


def generate_ansible_coverage_config() -> str:
    """Generate code coverage configuration for Ansible tests."""
    coverage_config = '''
[run]
branch = True
concurrency = multiprocessing
parallel = True

omit =
    */python*/dist-packages/*
    */python*/site-packages/*
    */python*/distutils/*
    */pyshared/*
    */pytest
    */AnsiballZ_*.py
    */test/results/*
'''

    return coverage_config


def generate_collection_coverage_config(args: TestConfig) -> str:
    """Generate code coverage configuration for Ansible Collection tests."""
    coverage_config = '''
[run]
branch = True
concurrency = multiprocessing
parallel = True
disable_warnings =
    no-data-collected
'''

    if isinstance(args, IntegrationConfig):
        coverage_config += '''
include =
    %s/*
    */%s/*
''' % (data_context().content.root, data_context().content.collection.directory)
    elif isinstance(args, SanityConfig):
        # temporary work-around for import sanity test
        coverage_config += '''
include =
    %s/*

omit =
    %s/*
''' % (data_context().content.root, os.path.join(data_context().content.root, data_context().content.results_path))
    else:
        coverage_config += '''
include =
     %s/*
''' % data_context().content.root

    return coverage_config


def self_check() -> None:
    """Check for internal errors due to incorrect code changes."""
    # Verify all supported Python versions have a coverage version.
    for version in SUPPORTED_PYTHON_VERSIONS:
        get_coverage_version(version)

    # Verify all controller Python versions are mapped to the latest coverage version.
    for version in CONTROLLER_PYTHON_VERSIONS:
        if get_coverage_version(version) != CONTROLLER_COVERAGE_VERSION:
            raise InternalError(f'Controller Python version {version} is not mapped to the latest coverage version.')


self_check()