# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

import atexit
import itertools
import re
import string

import yaml

from . import shared_telemetry_utils as utils
from .shared_telemetry_utils import ParserError

atexit.register(ParserError.exit_func)

MAX_CATEGORY_NAME_LENGTH = 30
MAX_METHOD_NAME_LENGTH = 20
MAX_OBJECT_NAME_LENGTH = 20
MAX_EXTRA_KEYS_COUNT = 10
MAX_EXTRA_KEY_NAME_LENGTH = 15

IDENTIFIER_PATTERN = r"^[a-zA-Z][a-zA-Z0-9_.]*[a-zA-Z0-9]$"


def nice_type_name(t):
    if issubclass(t, str):
        return "string"
    return t.__name__


def convert_to_cpp_identifier(s, sep):
    return string.capwords(s, sep).replace(sep, "")


class OneOf:
    """This is a placeholder type for the TypeChecker below.
    It signals that the checked value should match one of the following arguments
    passed to the TypeChecker constructor.
    """

    pass


class AtomicTypeChecker:
    """Validate a simple value against a given type"""

    def __init__(self, instance_type):
        self.instance_type = instance_type

    def check(self, identifier, key, value):
        if not isinstance(value, self.instance_type):
            ParserError(
                "%s: Failed type check for %s - expected %s, got %s."
                % (
                    identifier,
                    key,
                    nice_type_name(self.instance_type),
                    nice_type_name(type(value)),
                )
            ).handle_later()


class MultiTypeChecker:
    """Validate a simple value against a list of possible types"""

    def __init__(self, *instance_types):
        if not instance_types:
            raise Exception("At least one instance type is required.")
        self.instance_types = instance_types

    def check(self, identifier, key, value):
        if not any(isinstance(value, i) for i in self.instance_types):
            ParserError(
                "%s: Failed type check for %s - got %s, expected one of:\n%s"
                % (
                    identifier,
                    key,
                    nice_type_name(type(value)),
                    " or ".join(map(nice_type_name, self.instance_types)),
                )
            ).handle_later()


class ListTypeChecker:
    """Validate a list of values against a given type"""

    def __init__(self, instance_type):
        self.instance_type = instance_type

    def check(self, identifier, key, value):
        if len(value) < 1:
            ParserError(
                "%s: Failed check for %s - list should not be empty."
                % (identifier, key)
            ).handle_now()

        for x in value:
            if not isinstance(x, self.instance_type):
                ParserError(
                    "%s: Failed type check for %s - expected list value type %s, got"
                    " %s."
                    % (
                        identifier,
                        key,
                        nice_type_name(self.instance_type),
                        nice_type_name(type(x)),
                    )
                ).handle_later()


class DictTypeChecker:
    """Validate keys and values of a dict against a given type"""

    def __init__(self, keys_instance_type, values_instance_type):
        self.keys_instance_type = keys_instance_type
        self.values_instance_type = values_instance_type

    def check(self, identifier, key, value):
        if len(value.keys()) < 1:
            ParserError(
                "%s: Failed check for %s - dict should not be empty."
                % (identifier, key)
            ).handle_now()
        for x in value.keys():
            if not isinstance(x, self.keys_instance_type):
                ParserError(
                    "%s: Failed dict type check for %s - expected key type %s, got "
                    "%s."
                    % (
                        identifier,
                        key,
                        nice_type_name(self.keys_instance_type),
                        nice_type_name(type(x)),
                    )
                ).handle_later()
        for k, v in value.items():
            if not isinstance(v, self.values_instance_type):
                ParserError(
                    "%s: Failed dict type check for %s - "
                    "expected value type %s for key %s, got %s."
                    % (
                        identifier,
                        key,
                        nice_type_name(self.values_instance_type),
                        k,
                        nice_type_name(type(v)),
                    )
                ).handle_later()


def type_check_event_fields(identifier, name, definition):
    """Perform a type/schema check on the event definition."""
    REQUIRED_FIELDS = {
        "objects": ListTypeChecker(str),
        "bug_numbers": ListTypeChecker(int),
        "notification_emails": ListTypeChecker(str),
        "record_in_processes": ListTypeChecker(str),
        "description": AtomicTypeChecker(str),
        "products": ListTypeChecker(str),
    }
    OPTIONAL_FIELDS = {
        "methods": ListTypeChecker(str),
        "release_channel_collection": AtomicTypeChecker(str),
        "expiry_version": AtomicTypeChecker(str),
        "extra_keys": DictTypeChecker(str, str),
        "operating_systems": ListTypeChecker(str),
    }
    ALL_FIELDS = REQUIRED_FIELDS.copy()
    ALL_FIELDS.update(OPTIONAL_FIELDS)

    # Check that all the required fields are available.
    missing_fields = [f for f in REQUIRED_FIELDS.keys() if f not in definition]
    if len(missing_fields) > 0:
        ParserError(
            identifier + ": Missing required fields: " + ", ".join(missing_fields)
        ).handle_now()

    # Is there any unknown field?
    unknown_fields = [f for f in definition.keys() if f not in ALL_FIELDS]
    if len(unknown_fields) > 0:
        ParserError(
            identifier + ": Unknown fields: " + ", ".join(unknown_fields)
        ).handle_later()

    # Type-check fields.
    for k, v in definition.items():
        ALL_FIELDS[k].check(identifier, k, v)


def string_check(identifier, field, value, min_length=1, max_length=None, regex=None):
    # Length check.
    if len(value) < min_length:
        ParserError(
            "%s: Value '%s' for field %s is less than minimum length of %d."
            % (identifier, value, field, min_length)
        ).handle_later()
    if max_length and len(value) > max_length:
        ParserError(
            "%s: Value '%s' for field %s is greater than maximum length of %d."
            % (identifier, value, field, max_length)
        ).handle_later()
    # Regex check.
    if regex and not re.match(regex, value):
        ParserError(
            '%s: String value "%s" for %s is not matching pattern "%s".'
            % (identifier, value, field, regex)
        ).handle_later()


class EventData:
    """A class representing one event."""

    def __init__(self, category, name, definition, strict_type_checks=False):
        self._category = category
        self._name = name
        self._definition = definition
        self._strict_type_checks = strict_type_checks

        type_check_event_fields(self.identifier, name, definition)

        # Check method & object string patterns.
        if strict_type_checks:
            for method in self.methods:
                string_check(
                    self.identifier,
                    field="methods",
                    value=method,
                    min_length=1,
                    max_length=MAX_METHOD_NAME_LENGTH,
                    regex=IDENTIFIER_PATTERN,
                )
            for obj in self.objects:
                string_check(
                    self.identifier,
                    field="objects",
                    value=obj,
                    min_length=1,
                    max_length=MAX_OBJECT_NAME_LENGTH,
                    regex=IDENTIFIER_PATTERN,
                )

        # Check release_channel_collection
        rcc_key = "release_channel_collection"
        rcc = definition.get(rcc_key, "opt-in")
        allowed_rcc = ["opt-in", "opt-out"]
        if rcc not in allowed_rcc:
            ParserError(
                "%s: Value for %s should be one of: %s"
                % (self.identifier, rcc_key, ", ".join(allowed_rcc))
            ).handle_later()

        # Check record_in_processes.
        record_in_processes = definition.get("record_in_processes")
        for proc in record_in_processes:
            if not utils.is_valid_process_name(proc):
                ParserError(
                    self.identifier + ": Unknown value in record_in_processes: " + proc
                ).handle_later()

        # Check products.
        products = definition.get("products")
        for product in products:
            if not utils.is_valid_product(product) and self._strict_type_checks:
                ParserError(
                    self.identifier + ": Unknown value in products: " + product
                ).handle_later()

        # Check operating_systems.
        operating_systems = definition.get("operating_systems", [])
        for operating_system in operating_systems:
            if not utils.is_valid_os(operating_system):
                ParserError(
                    self.identifier
                    + ": Unknown value in operating_systems: "
                    + operating_system
                ).handle_later()

        # Check extra_keys.
        extra_keys = definition.get("extra_keys", {})
        if len(extra_keys.keys()) > MAX_EXTRA_KEYS_COUNT:
            ParserError(
                "%s: Number of extra_keys exceeds limit %d."
                % (self.identifier, MAX_EXTRA_KEYS_COUNT)
            ).handle_later()
        for key in extra_keys.keys():
            string_check(
                self.identifier,
                field="extra_keys",
                value=key,
                min_length=1,
                max_length=MAX_EXTRA_KEY_NAME_LENGTH,
                regex=IDENTIFIER_PATTERN,
            )

        # Check expiry.
        if "expiry_version" not in definition:
            ParserError(
                "%s: event is missing required field expiry_version" % (self.identifier)
            ).handle_later()

        # Finish setup.
        # Historical versions of Events.yaml may contain expiration versions
        # using the deprecated format 'N.Na1'. Those scripts set
        # self._strict_type_checks to false.
        expiry_version = definition.get("expiry_version", "never")
        if (
            not utils.validate_expiration_version(expiry_version)
            and self._strict_type_checks
        ):
            ParserError(
                "{}: invalid expiry_version: {}.".format(
                    self.identifier, expiry_version
                )
            ).handle_now()
        definition["expiry_version"] = utils.add_expiration_postfix(expiry_version)

    @property
    def category(self):
        return self._category

    @property
    def category_cpp(self):
        # Transform e.g. category.example into CategoryExample.
        return convert_to_cpp_identifier(self._category, ".")

    @property
    def name(self):
        return self._name

    @property
    def identifier(self):
        return self.category + "#" + self.name

    @property
    def methods(self):
        return self._definition.get("methods", [self.name])

    @property
    def objects(self):
        return self._definition.get("objects")

    @property
    def record_in_processes(self):
        return self._definition.get("record_in_processes")

    @property
    def record_in_processes_enum(self):
        """Get the non-empty list of flags representing the processes to record data in"""
        return [utils.process_name_to_enum(p) for p in self.record_in_processes]

    @property
    def products(self):
        """Get the non-empty list of products to record data on"""
        return self._definition.get("products")

    @property
    def products_enum(self):
        """Get the non-empty list of flags representing products to record data on"""
        return [utils.product_name_to_enum(p) for p in self.products]

    @property
    def expiry_version(self):
        return self._definition.get("expiry_version")

    @property
    def operating_systems(self):
        """Get the list of operating systems to record data on"""
        return self._definition.get("operating_systems", ["all"])

    def record_on_os(self, target_os):
        """Check if this probe should be recorded on the passed os."""
        os = self.operating_systems
        if "all" in os:
            return True

        canonical_os = utils.canonical_os(target_os)

        if "unix" in os and canonical_os in utils.UNIX_LIKE_OS:
            return True

        return canonical_os in os

    @property
    def enum_labels(self):
        def enum(method_name, object_name):
            m = convert_to_cpp_identifier(method_name, "_")
            o = convert_to_cpp_identifier(object_name, "_")
            return m + "_" + o

        combinations = itertools.product(self.methods, self.objects)
        return [enum(t[0], t[1]) for t in combinations]

    @property
    def dataset(self):
        """Get the nsITelemetry constant equivalent for release_channel_collection."""
        rcc = self.dataset_short
        if rcc == "opt-out":
            return "nsITelemetry::DATASET_ALL_CHANNELS"
        return "nsITelemetry::DATASET_PRERELEASE_CHANNELS"

    @property
    def dataset_short(self):
        """Get the short name of the chosen release channel collection policy for the event."""
        # The collection policy is optional, but we still define a default
        # behaviour for it.
        return self._definition.get("release_channel_collection", "opt-in")

    @property
    def extra_keys(self):
        return list(sorted(self._definition.get("extra_keys", {}).keys()))


def load_events(filename, strict_type_checks):
    """Parses a YAML file containing the event definitions.

    :param filename: the YAML file containing the event definitions.
    :strict_type_checks A boolean indicating whether to use the stricter type checks.
    :raises ParserError: if the event file cannot be opened or parsed.
    """

    # Parse the event definitions from the YAML file.
    events = None
    try:
        with open(filename, "r") as f:
            events = yaml.safe_load(f)
    except IOError as e:
        ParserError("Error opening " + filename + ": " + str(e) + ".").handle_now()
    except ParserError as e:
        ParserError(
            "Error parsing events in " + filename + ": " + str(e) + "."
        ).handle_now()

    event_list = []

    # Events are defined in a fixed two-level hierarchy within the definition file.
    # The first level contains the category (group name), while the second level contains
    # the event names and definitions, e.g.:
    #   category.name:
    #     event_name:
    #       <event definition>
    #      ...
    #   ...
    for category_name, category in sorted(events.items()):
        string_check(
            "top level structure",
            field="category",
            value=category_name,
            min_length=1,
            max_length=MAX_CATEGORY_NAME_LENGTH,
            regex=IDENTIFIER_PATTERN,
        )

        # Make sure that the category has at least one entry in it.
        if not category or len(category) == 0:
            ParserError(
                "Category " + category_name + " must contain at least one entry."
            ).handle_now()

        for name, entry in sorted(category.items()):
            string_check(
                category_name,
                field="event name",
                value=name,
                min_length=1,
                max_length=MAX_METHOD_NAME_LENGTH,
                regex=IDENTIFIER_PATTERN,
            )
            event_list.append(EventData(category_name, name, entry, strict_type_checks))

    return event_list