#!/usr/bin/env python3

# Copyright 2022 gRPC authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
Generate experiment related code artifacts.

Invoke as: tools/codegen/core/gen_experiments.py
Experiment definitions are in src/core/lib/experiments/experiments.yaml
"""

from __future__ import print_function

import argparse
import sys

import experiments_compiler as exp
import yaml

DEFAULTS = {
    "broken": "false",
    False: "false",
    True: "true",
    "debug": "kDefaultForDebugOnly",
}

FINAL_RETURN = {
    "broken": "return false;",
    False: "return false;",
    True: "return true;",
    "debug": "\n#ifdef NDEBUG\nreturn false;\n#else\nreturn true;\n#endif\n",
}

FINAL_DEFINE = {
    "broken": None,
    False: None,
    True: "#define %s",
    "debug": "#ifndef NDEBUG\n#define %s\n#endif",
}

BZL_LIST_FOR_DEFAULTS = {
    "broken": None,
    False: "off",
    True: "on",
    "debug": "dbg",
}


def ParseCommandLineArguments(args):
    """Wrapper for argparse command line arguments handling.

    Args:
    args: List of command line arguments.

    Returns:
    Command line arguments namespace built by argparse.ArgumentParser().
    """
    # formatter_class=argparse.ArgumentDefaultsHelpFormatter is not used here
    # intentionally, We want more formatting than this class can provide.
    flag_parser = argparse.ArgumentParser()
    flag_parser.add_argument(
        "--check",
        action="store_false",
        help="If specified, disables checking experiment expiry dates",
    )
    flag_parser.add_argument(
        "--disable_gen_hdrs",
        action="store_true",
        help="If specified, disables generation of experiments hdr files",
    )
    flag_parser.add_argument(
        "--disable_gen_srcs",
        action="store_true",
        help="If specified, disables generation of experiments source files",
    )
    flag_parser.add_argument(
        "--disable_gen_bzl",
        action="store_true",
        help="If specified, disables generation of experiments.bzl file",
    )
    return flag_parser.parse_args(args)


args = ParseCommandLineArguments(sys.argv[1:])

with open("src/core/lib/experiments/experiments.yaml") as f:
    attrs = yaml.safe_load(f.read())

with open("src/core/lib/experiments/rollouts.yaml") as f:
    rollouts = yaml.safe_load(f.read())

compiler = exp.ExperimentsCompiler(
    DEFAULTS, FINAL_RETURN, FINAL_DEFINE, BZL_LIST_FOR_DEFAULTS
)

experiment_annotation = "gRPC Experiments: "
for attr in attrs:
    exp_definition = exp.ExperimentDefinition(attr)
    if not exp_definition.IsValid(args.check):
        sys.exit(1)
    experiment_annotation += exp_definition.name + ":0,"
    if not compiler.AddExperimentDefinition(exp_definition):
        print("Experiment = %s ERROR adding" % exp_definition.name)
        sys.exit(1)

if len(experiment_annotation) > 2000:
    print("comma-delimited string of experiments is too long")
    sys.exit(1)

for rollout_attr in rollouts:
    if not compiler.AddRolloutSpecification(rollout_attr):
        print("ERROR adding rollout spec")
        sys.exit(1)

if not args.disable_gen_hdrs:
    print("Generating experiments headers")
    compiler.GenerateExperimentsHdr("src/core/lib/experiments/experiments.h")

if not args.disable_gen_srcs:
    print("Generating experiments srcs")
    compiler.GenerateExperimentsSrc("src/core/lib/experiments/experiments.cc")

if not args.disable_gen_bzl:
    print("Generating experiments.bzl")
    compiler.GenExperimentsBzl("bazel/experiments.bzl")