import datetime
import json
import logging
import os
import re
import socket
import sys
import time
from contextlib import contextmanager
from functools import wraps
from http.client import HTTPMessage
from typing import Any, Dict, List, Mapping, Optional, Tuple, Union
from urllib import error, request
from urllib.parse import urlparse

from uaclient import event_logger, exceptions, messages
from uaclient.defaults import CONFIG_FIELD_ENVVAR_ALLOWLIST
from uaclient.types import MessagingOperations

DROPPED_KEY = object()

UA_NO_PROXY_URLS = ("169.254.169.254", "metadata", "[fd00:ec2::254]")
PROXY_VALIDATION_APT_HTTP_URL = "http://archive.ubuntu.com"
PROXY_VALIDATION_APT_HTTPS_URL = "https://esm.ubuntu.com"
PROXY_VALIDATION_SNAP_HTTP_URL = "http://api.snapcraft.io"
PROXY_VALIDATION_SNAP_HTTPS_URL = "https://api.snapcraft.io"


event = event_logger.get_event_logger()


class LogFormatter(logging.Formatter):

    FORMATS = {
        logging.ERROR: "ERROR: %(message)s",
        logging.DEBUG: "DEBUG: %(message)s",
    }

    def format(self, record: logging.LogRecord) -> str:
        log_fmt = self.FORMATS.get(record.levelno, "%(message)s")
        return logging.Formatter(log_fmt).format(record)


class DatetimeAwareJSONEncoder(json.JSONEncoder):
    """A json.JSONEncoder subclass that writes out isoformat'd datetimes."""

    def default(self, o):
        if isinstance(o, datetime.datetime):
            return o.isoformat()
        return super().default(o)


class DatetimeAwareJSONDecoder(json.JSONDecoder):
    """
    A JSONDecoder that parses some ISO datetime strings to datetime objects.

    Important note: the "some" is because we seem to only be able extend
    Python's json library in a way that lets us convert string values within
    JSON objects (e.g. '{"lastModified": "2019-07-25T14:35:51"}'). Strings
    outside of JSON objects (e.g. '"2019-07-25T14:35:51"') will not be passed
    through our decoder.

    (N.B. This will override any object_hook specified using arguments to it,
    or used in load or loads calls that specify this as the cls.)
    """

    def __init__(self, *args, **kwargs):
        if "object_hook" in kwargs:
            kwargs.pop("object_hook")
        super().__init__(*args, object_hook=self.object_hook, **kwargs)

    @staticmethod
    def object_hook(o):
        for key, value in o.items():
            if isinstance(value, str):
                try:
                    new_value = parse_rfc3339_date(value)
                except ValueError:
                    # This isn't a string containing a valid ISO 8601 datetime
                    new_value = value
                o[key] = new_value
        return o


@contextmanager
def disable_log_to_console():
    """
    A context manager that disables logging to console in its body

    N.B. This _will not_ disable console logging if it finds the console
    handler is configured at DEBUG level; the assumption is that this means we
    want as much output as possible, even if it risks duplication.

    This context manager will allow us to gradually move away from using the
    logging framework for user-facing output, by applying it to parts of the
    codebase piece-wise. (Once the conversion is complete, we should have no
    further use for it and it can be removed.)

    (Note that the @contextmanager decorator also allows this function to be
    used as a decorator.)
    """
    potential_handlers = [
        handler
        for handler in logging.getLogger().handlers
        if handler.name == "ua-console"
    ]
    if not potential_handlers:
        # We didn't find a handler, so execute the body as normal then end
        # execution
        logging.debug("disable_log_to_console: no console handler found")
        yield
        return

    console_handler = potential_handlers[0]
    old_level = console_handler.level
    if old_level == logging.DEBUG:
        yield
        return

    console_handler.setLevel(1000)
    try:
        yield
    finally:
        console_handler.setLevel(old_level)


def retry(exception, retry_sleeps):
    """Decorator to retry on exception for retry_sleeps.

    @param retry_sleeps: List of sleep lengths to apply between
       retries. Specifying a list of [0.5, 1] tells subp to retry twice
       on failure; sleeping half a second before the first retry and 1 second
       before the second retry.
    @param exception: The exception class to catch and retry for the provided
       retry_sleeps. Any other exception types will not be caught by the
       decorator.
    """

    def wrapper(f):
        @wraps(f)
        def decorator(*args, **kwargs):
            sleeps = retry_sleeps.copy()
            while True:
                try:
                    return f(*args, **kwargs)
                except exception as e:
                    if not sleeps:
                        raise e
                    retry_msg = " Retrying %d more times." % len(sleeps)
                    logging.debug(str(e) + retry_msg)
                    time.sleep(sleeps.pop(0))

        return decorator

    return wrapper


def get_dict_deltas(
    orig_dict: Dict[str, Any], new_dict: Dict[str, Any], path: str = ""
) -> Dict[str, Any]:
    """Return a dictionary of delta between orig_dict and new_dict."""
    deltas = {}  # type: Dict[str, Any]
    for key, value in orig_dict.items():
        new_value = new_dict.get(key, DROPPED_KEY)
        key_path = key if not path else path + "." + key
        if isinstance(value, dict):
            if key in new_dict:
                sub_delta = get_dict_deltas(
                    value, new_dict[key], path=key_path
                )
                if sub_delta:
                    deltas[key] = sub_delta
            else:
                deltas[key] = DROPPED_KEY
        elif value != new_value:
            log = (
                "Contract value for '"
                + key_path
                + "' changed to '"
                + str(new_value)
                + "'"
            )
            logging.debug(redact_sensitive_logs(log))
            deltas[key] = new_value
    for key, value in new_dict.items():
        if key not in orig_dict:
            deltas[key] = value
    return deltas


def is_service_url(url: str) -> bool:
    try:
        parsed_url = urlparse(url)
    except ValueError:
        return False

    if parsed_url.scheme not in ("https", "http"):
        return False

    try:
        parsed_url.port
    except ValueError:
        return False

    return True


def prompt_choices(msg: str = "", valid_choices: List[str] = []) -> str:
    """Interactive prompt message, returning a valid choice from msg.

    Expects a structured msg which designates choices with square brackets []
    around the characters which indicate a valid choice.

    Uppercase and lowercase responses are allowed. Loop on invalid choices.

    :return: Valid response character chosen.
    """
    value = ""
    error_msg = "{} is not one of: {}".format(
        value, ", ".join([choice.upper() for choice in valid_choices])
    )
    while True:
        event.info(msg)
        value = input("> ").lower()
        if value in valid_choices:
            break
        event.info(error_msg)
    return value


def prompt_for_confirmation(
    msg: str = "", assume_yes: bool = False, default: bool = False
) -> bool:
    """
    Display a confirmation prompt, returning a bool indicating the response

    :param msg: String custom prompt text to emit from input call.
    :param assume_yes: Boolean set True to skip confirmation input and return
        True.
    :param default: Boolean to return when user doesn't enter any text

    This function will only prompt a single time, and defaults to "no" (i.e. it
    returns False).
    """
    if assume_yes:
        return True
    if not msg:
        msg = messages.PROMPT_YES_NO
    value = input(msg).lower().strip()
    if value == "":
        return default
    if value in ["y", "yes"]:
        return True
    return False


def configure_web_proxy(
    http_proxy: Optional[str], https_proxy: Optional[str]
) -> None:
    """
    Configure urllib to use http and https proxies.

    :param http_proxy: http proxy to be used by urllib. If None, it will
                       not be configured
    :param https_proxy: https proxy to be used by urllib. If None, it will
                        not be configured
    """
    proxy_dict = {}

    if http_proxy:
        proxy_dict["http"] = http_proxy

    if https_proxy:
        proxy_dict["https"] = https_proxy

    # Default no_proxy if absense of NO_PROXY, no_proxy environment vars.
    no_proxy = ",".join(sorted(UA_NO_PROXY_URLS))
    for env_var in ("no_proxy", "NO_PROXY"):
        proxy_value = os.environ.get(env_var)
        if proxy_value:
            # Honor no proxy values and extend UA-specific where absent
            no_proxy = ",".join(
                sorted(
                    set(proxy_value.split(",")).union(set(UA_NO_PROXY_URLS))
                )
            )
    logging.debug("Setting no_proxy: %s", no_proxy)
    os.environ["no_proxy"] = no_proxy
    os.environ["NO_PROXY"] = no_proxy
    if proxy_dict:
        proxy_handler = request.ProxyHandler(proxy_dict)
        opener = request.build_opener(proxy_handler)
        request.install_opener(opener)


def readurl(
    url: str,
    data: Optional[bytes] = None,
    headers: Dict[str, str] = {},
    method: Optional[str] = None,
    timeout: Optional[int] = None,
    potentially_sensitive: bool = True,
) -> Tuple[Any, Union[HTTPMessage, Mapping[str, str]]]:
    if data and not method:
        method = "POST"
    req = request.Request(url, data=data, headers=headers, method=method)
    sorted_header_str = ", ".join(
        ["'{}': '{}'".format(k, headers[k]) for k in sorted(headers)]
    )
    logging.debug(
        redact_sensitive_logs(
            "URL [{}]: {}, headers: {{{}}}, data: {}".format(
                method or "GET",
                url,
                sorted_header_str,
                data.decode("utf-8") if data else None,
            )
        )
    )
    http_error_found = False
    try:
        resp = request.urlopen(req, timeout=timeout)
        http_error_found = False
    except error.HTTPError as e:
        resp = e
        http_error_found = True
    setattr(resp, "body", resp.read().decode("utf-8"))
    content = resp.body
    if "application/json" in str(resp.headers.get("Content-type", "")):
        content = json.loads(content)
    sorted_header_str = ", ".join(
        ["'{}': '{}'".format(k, resp.headers[k]) for k in sorted(resp.headers)]
    )
    debug_msg = "URL [{}] response: {}, headers: {{{}}}, data: {}".format(
        method or "GET", url, sorted_header_str, content
    )
    if potentially_sensitive:
        # For large responses, this is very slow (several minutes)
        debug_msg = redact_sensitive_logs(debug_msg)
    logging.debug(debug_msg)
    if http_error_found:
        raise resp
    return content, resp.headers


def is_config_value_true(config: Dict[str, Any], path_to_value: str):
    """Check if value parameter can be translated into a boolean 'True' value.

    @param config: A config dict representing
                   /etc/ubuntu-advantange/uaclient.conf
    @param path_to_value: The path from where the value parameter was
                          extracted.
    @return: A boolean value indicating if the value paramater corresponds
             to a 'True' boolean value.
    @raises exceptions.UserFacingError when the value provide by the
            path_to_value parameter can not be translated into either
            a 'False' or 'True' boolean value.
    """
    value = config
    default_value = {}  # type: Any
    paths = path_to_value.split(".")
    leaf_value = paths[-1]
    for key in paths:
        if key == leaf_value:
            default_value = "false"

        if isinstance(value, dict):
            value = value.get(key, default_value)
        else:
            return False

    value_str = str(value)
    if value_str.lower() == "true":
        return True
    elif value_str.lower() == "false":
        return False
    else:
        raise exceptions.UserFacingError(
            messages.ERROR_INVALID_CONFIG_VALUE.format(
                path_to_value=path_to_value,
                expected_value="boolean string: true or false",
                value=value_str,
            )
        )


REDACT_SENSITIVE_LOGS = [
    r"(Bearer )[^\']+",
    r"(\'attach\', \')[^\']+",
    r"(\'machineToken\': \')[^\']+",
    r"(\'token\': \')[^\']+",
    r"(\'X-aws-ec2-metadata-token\': \')[^\']+",
    r"(.*\[PUT\] response.*api/token,.*data: ).*",
    r"(https://bearer:)[^\@]+",
    r"(/snap/bin/canonical-livepatch\s+enable\s+)[^\s]+",
    r"(Contract\s+value\s+for\s+'resourceToken'\s+changed\s+to\s+).*",
    r"(\'resourceToken\': \')[^\']+",
    r"(\'contractToken\': \')[^\']+",
    r"(https://contracts.canonical.com/v1/resources/livepatch\?token=)[^\s]+",
    r"(\"identityToken\": \")[^\"]+",
    r"(response:\s+http://metadata/computeMetadata/v1/instance/"
    "service-accounts.*data: ).*",
    r"(\'token\': \')[^\']+",
    r"(\'userCode\': \')[^\']+",
    r"(\'magic_token=)[^\']+",
]


def redact_sensitive_logs(
    log, redact_regexs: List[str] = REDACT_SENSITIVE_LOGS
) -> str:
    """Redact known sensitive information from log content."""
    redacted_log = log
    for redact_regex in redact_regexs:
        redacted_log = re.sub(redact_regex, r"\g<1><REDACTED>", redacted_log)
    return redacted_log


def handle_message_operations(
    msg_ops: Optional[MessagingOperations],
) -> bool:
    """Emit messages to the console for user interaction

    :param msg_op: A list of strings or tuples. Any string items are printed.
        Any tuples will contain a callable and a dict of args to pass to the
        callable. Callables are expected to return True on success and
        False upon failure.

    :return: True upon success, False on failure.
    """
    if not msg_ops:
        return True

    for msg_op in msg_ops:
        if isinstance(msg_op, str):
            event.info(msg_op)
        else:  # Then we are a callable and dict of args
            functor, args = msg_op
            if not functor(**args):
                return False
    return True


def parse_rfc3339_date(dt_str: str) -> datetime.datetime:
    """
    Parse a datestring in rfc3339 format. Originally written for compatibility
    with golang's time.MarshalJSON function. Also handles output of pythons
    isoformat datetime method.

    This drops subseconds.

    :param dt_str: a date string in rfc3339 format

    :return: datetime.datetime object of time represented by dt_str
    """
    # remove sub-seconds
    # Examples:
    #   Before: "2001-02-03T04:05:06.123456"
    #   After: "2001-02-03T04:05:06"
    #   Before: "2001-02-03T04:05:06.123456Z"
    #   After: "2001-02-03T04:05:06Z"
    #   Before: "2001-02-03T04:05:06.123456+09:00"
    #   After: "2001-02-03T04:05:06+09:00"
    dt_str_without_subseconds = re.sub(
        r"(\d{2}:\d{2}:\d{2})\.\d+", r"\g<1>", dt_str
    )
    # if there is no timezone info, assume UTC
    # Examples:
    #   Before: "2001-02-03T04:05:06"
    #   After: "2001-02-03T04:05:06Z"
    #   Before: "2001-02-03T04:05:06Z"
    #   After: "2001-02-03T04:05:06Z"
    #   Before: "2001-02-03T04:05:06+09:00"
    #   After: "2001-02-03T04:05:06+09:00"
    dt_str_with_z = re.sub(
        r"(\d{2}:\d{2}:\d{2})$", r"\g<1>Z", dt_str_without_subseconds
    )
    # replace Z with offset for UTC
    # Examples:
    #   Before: "2001-02-03T04:05:06Z"
    #   After: "2001-02-03T04:05:06+00:00"
    #   Before: "2001-02-03T04:05:06+09:00"
    #   After: "2001-02-03T04:05:06+09:00"
    dt_str_without_z = dt_str_with_z.replace("Z", "+00:00")
    # change offset format to not include colon `:`
    # Examples:
    #   Before: "2001-02-03T04:05:06+00:00"
    #   After: "2001-02-03T04:05:06+0000"
    #   Before: "2001-02-03T04:05:06+09:00"
    #   After: "2001-02-03T04:05:06+0900"
    dt_str_with_pythonish_tz = re.sub(
        r"(-|\+)(\d{2}):(\d{2})$", r"\g<1>\g<2>\g<3>", dt_str_without_z
    )
    return datetime.datetime.strptime(
        dt_str_with_pythonish_tz, "%Y-%m-%dT%H:%M:%S%z"
    )


def validate_proxy(
    protocol: str, proxy: Optional[str], test_url: str
) -> Optional[str]:
    if not proxy:
        return None

    if not is_service_url(proxy):
        raise exceptions.ProxyInvalidUrl(proxy)

    req = request.Request(test_url, method="HEAD")
    proxy_handler = request.ProxyHandler({protocol: proxy})
    opener = request.build_opener(proxy_handler)

    try:
        opener.open(req)
        return proxy
    except (socket.timeout, error.URLError) as e:
        with disable_log_to_console():
            msg = getattr(e, "reason", str(e))
            logging.error(
                messages.ERROR_USING_PROXY.format(
                    proxy=proxy, test_url=test_url, error=msg
                )
            )
        raise exceptions.ProxyNotWorkingError(proxy)


def handle_unicode_characters(message: str) -> str:
    """
    Verify if the system can output unicode characters and if not,
    remove those characters from the message string.
    """
    if (
        sys.stdout.encoding is None
        or "UTF-8" not in sys.stdout.encoding.upper()
    ):
        # Replace our Unicode dash with an ASCII dash if we aren't going to be
        # writing to a utf-8 output; see
        # https://github.com/CanonicalLtd/ubuntu-advantage-client/issues/859
        message = message.replace("\u2014", "-")

        # Remove our unicode success/failure marks if we aren't going to be
        # writing to a utf-8 output; see
        # https://github.com/CanonicalLtd/ubuntu-advantage-client/issues/1463
        message = message.replace(messages.OKGREEN_CHECK + " ", "")
        message = message.replace(messages.FAIL_X + " ", "")

    return message


def get_pro_environment():
    return {
        k: v
        for k, v in os.environ.items()
        if k.lower() in CONFIG_FIELD_ENVVAR_ALLOWLIST
        or k.startswith("UA_FEATURES")
        or k == "UA_CONFIG_FILE"
    }


def depth_first_merge_overlay_dict(base_dict, overlay_dict):
    """Merge the contents of overlay dict into base_dict not only on top-level
    keys, but on all on the depths of the overlay_dict object. For example,
    using these values as entries for the function:

    base_dict = {"a": 1, "b": {"c": 2, "d": 3}}
    overlay_dict = {"b": {"c": 10}}

    Should update base_dict into:

    {"a": 1, "b": {"c": 10, "d": 3}}

    @param base_dict: The dict to be updated
    @param overlay_dict: The dict with information to be added into base_dict
    """

    def update_dict_list(base_values, overlay_values, key):
        merge_id_key_map = {
            "availableResources": "name",
            "resourceEntitlements": "type",
        }
        values_to_append = []
        id_key = merge_id_key_map.get(key)
        for overlay_value in overlay_values:
            was_replaced = False
            for base_value_idx, base_value in enumerate(base_values):
                if base_value.get(id_key) == overlay_value.get(id_key):
                    depth_first_merge_overlay_dict(base_value, overlay_value)
                    was_replaced = True

            if not was_replaced:
                values_to_append.append(overlay_value)

        base_values.extend(values_to_append)

    for key, value in overlay_dict.items():
        base_value = base_dict.get(key)
        if isinstance(base_value, dict) and isinstance(value, dict):
            depth_first_merge_overlay_dict(base_dict[key], value)
        elif isinstance(base_value, list) and isinstance(value, list):
            if len(base_value) and isinstance(base_value[0], dict):
                update_dict_list(base_dict[key], value, key=key)
            else:
                """
                Most other lists which aren't lists of dicts are lists of
                strs. Replace that list # with the overlay value."""
                base_dict[key] = value
        else:
            base_dict[key] = value
