# 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/.

"""
Outputter to generate Rust code for metrics.
"""

import enum
import json
import sys

import jinja2
from glean_parser import util
from glean_parser.metrics import Rate
from util import type_ids_and_categories

from js import ID_BITS, PING_INDEX_BITS

RUNTIME_METRIC_BIT = ID_BITS - 1
RUNTIME_PING_BIT = PING_INDEX_BITS - 1

# The list of all args to CommonMetricData.
# No particular order is required, but I have these in common_metric_data.rs
# order just to be organized.
# Note that this is util.common_metric_args with "dynamic_label" in the spot
# expected by glean-core's CommonMetricData.
common_metric_data_args = [
    "name",
    "category",
    "send_in_pings",
    "lifetime",
    "disabled",
    "dynamic_label",
    "in_session",
]

# List of all metric-type-specific args that JOG understands.
known_extra_args = [
    "time_unit",
    "memory_unit",
    "allowed_extra_keys",
    "reason_codes",
    "range_min",
    "range_max",
    "bucket_count",
    "histogram_type",
    "numerators",
    "ordered_labels",
    "ordered_keys",
    "ordered_categories",
]

# List of all metric-type-specific metadata that JOG understands.
# We map them to extra_args.
known_metadata = [
    "permit_non_commutative_operations_over_ipc",
]

# List of all ping-specific args that JOG understands.
known_ping_args = [
    "name",
    "include_client_id",
    "send_if_empty",
    "precise_timestamps",
    "include_info_sections",
    "enabled",
    "schedules_pings",
    "reason_codes",
    "follows_collection_enabled",
    "uploader_capabilities",
]


def ensure_jog_support_for_args():
    """
    glean_parser or the Glean SDK might add new metric/ping args.
    To ensure JOG doesn't fall behind in support,
    we check the list of JOG-supported args vs glean_parser's.
    We fail the build if glean_parser has one or more we haven't seen before.
    """

    unknown_args = set(util.extra_metric_args) - set(known_extra_args)

    unknown_args |= set(util.ping_args) - set(known_ping_args)

    if len(unknown_args):
        print(f"Unknown glean_parser args {unknown_args}")
        print("JOG must be updated to support the new args")
        sys.exit(1)


def load_monkeypatches():
    """
    Monkeypatch jinja template loading because we're not glean_parser.
    We're glean_parser_ext.
    """

    # Monkeypatch util.get_jinja2_template to find templates nearby
    def get_local_template(template_name, filters=()):
        env = jinja2.Environment(
            loader=jinja2.PackageLoader("rust", "templates"),
            trim_blocks=True,
            lstrip_blocks=True,
        )
        env.filters["camelize"] = util.camelize
        env.filters["Camelize"] = util.Camelize
        for filter_name, filter_func in filters:
            env.filters[filter_name] = filter_func
        return env.get_template(template_name)

    util.get_jinja2_template = get_local_template


def sometimes_supports_noncommutative_operations(metric_type_name):
    return metric_type_name in ("boolean", "labeled_boolean", "quantity")


def output_factory(objs, output_fd, options={}):
    """
    Given a tree of objects, output Rust code to the file-like object `output_fd`.
    Specifically, Rust code that can generate Rust metrics instances.

    :param objs: A tree of objects (metrics and pings) as returned from
    `parser.parse_objects`.
    :param output_fd: Writeable file to write the output to.
    :param options: options dictionary, presently unused.
    """

    ensure_jog_support_for_args()
    load_monkeypatches()

    # Get the metric type ids. Must be the same ids generated in js.py
    metric_types, categories = type_ids_and_categories(objs)

    template = util.get_jinja2_template(
        "jog_factory.jinja2",
        filters=(("snake_case", util.snake_case),),
    )

    output_fd.write(
        template.render(
            common_metric_data_args=common_metric_data_args,
            extra_args=util.extra_args,
            metric_types=metric_types,
            runtime_metric_bit=RUNTIME_METRIC_BIT,
            runtime_ping_bit=RUNTIME_PING_BIT,
            sometimes_supports_noncommutative_operations=sometimes_supports_noncommutative_operations,
            ID_BITS=ID_BITS,
        )
    )
    output_fd.write("\n")


def camel_to_snake(s):
    assert "_" not in s, "JOG doesn't encode metric typenames with underscores"
    return "".join(["_" + c.lower() if c.isupper() else c for c in s]).lstrip("_")


def output_file(objs, output_fd, options={}):
    """
    Given a tree of objects, output them to the file-like object `output_fd`.
    Specifically, in a format that describes all the metrics and pings defined in objs.

    :param objs: A tree of objects (metrics and pings) as returned from
                 `parser.parse_objects`.
                 Presently a dictionary with keys of literals "pings" and "tags"
                 as well as one key per metric category mapped to lists of
                 pings, tags, and metrics (respecitvely)
    :param output_fd: Writeable file to write the output to.
    :param options: options dictionary, presently unused.
    """

    ensure_jog_support_for_args()

    jog_data = {"pings": [], "metrics": {}}

    if "tags" in objs:
        del objs["tags"]  # JOG has no use for tags.

    pings = objs["pings"]
    del objs["pings"]
    for ping in pings.values():
        ping_arg_list = []
        for arg in known_ping_args:
            if hasattr(ping, arg):
                ping_arg_list.append(getattr(ping, arg))
        jog_data["pings"].append(ping_arg_list)

    def encode(value):
        if isinstance(value, enum.Enum):
            return value.name
        if isinstance(value, Rate):  # `numerators` for an external Denominator metric
            args = []
            for arg_name in common_metric_data_args:
                if arg_name == "dynamic_label":
                    # "dynamic_label" is special because it is on the Rust
                    # CommonMetricData struct, but isn't in the glean_parser
                    # object model.
                    # Luckily, JOG doesn't need it. So merely supply None.
                    args.append(None)
                    continue
                args.append(getattr(value, arg_name))

            return args
        return json.dumps(value)

    for category, metrics in objs.items():
        dict_cat = jog_data["metrics"].setdefault(category, [])
        for metric in metrics.values():
            metric_arg_list = [camel_to_snake(metric.__class__.__name__)]
            for arg in common_metric_data_args:
                if arg in ["category", "dynamic_label"]:
                    continue
                metric_arg_list.append(getattr(metric, arg))
            extra = {}
            for arg in known_extra_args:
                if hasattr(metric, arg):
                    extra[arg] = getattr(metric, arg)
            for meta in known_metadata:
                if meta in metric.metadata:
                    extra[meta] = metric.metadata.get(meta)
            if extra:
                metric_arg_list.append(extra)
            dict_cat.append(metric_arg_list)

    # TODO: Measure the speed gain of removing `indent=2`
    json.dump(jog_data, output_fd, sort_keys=True, default=encode, indent=2)
