#!/usr/bin/env python

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import argparse
import yaml

import ray
from ray.tests.cluster_utils import Cluster
from ray.tune.config_parser import make_parser
from ray.tune.result import DEFAULT_RESULTS_DIR
from ray.tune.resources import resources_to_json
from ray.tune.tune import _make_scheduler, run_experiments

EXAMPLE_USAGE = """
Training example via RLlib CLI:
    rllib train --run DQN --env CartPole-v0

Grid search example via RLlib CLI:
    rllib train -f tuned_examples/cartpole-grid-search-example.yaml

Grid search example via executable:
    ./train.py -f tuned_examples/cartpole-grid-search-example.yaml

Note that -f overrides all other trial-specific command-line options.
"""


def create_parser(parser_creator=None):
    parser = make_parser(
        parser_creator=parser_creator,
        formatter_class=argparse.RawDescriptionHelpFormatter,
        description="Train a reinforcement learning agent.",
        epilog=EXAMPLE_USAGE)

    # See also the base parser definition in ray/tune/config_parser.py
    parser.add_argument(
        "--ray-address",
        default=None,
        type=str,
        help="Connect to an existing Ray cluster at this address instead "
        "of starting a new one.")
    parser.add_argument(
        "--ray-num-cpus",
        default=None,
        type=int,
        help="--num-cpus to use if starting a new cluster.")
    parser.add_argument(
        "--ray-num-gpus",
        default=None,
        type=int,
        help="--num-gpus to use if starting a new cluster.")
    parser.add_argument(
        "--ray-num-nodes",
        default=None,
        type=int,
        help="Emulate multiple cluster nodes for debugging.")
    parser.add_argument(
        "--ray-redis-max-memory",
        default=None,
        type=int,
        help="--redis-max-memory to use if starting a new cluster.")
    parser.add_argument(
        "--ray-memory",
        default=None,
        type=int,
        help="--memory to use if starting a new cluster.")
    parser.add_argument(
        "--ray-object-store-memory",
        default=None,
        type=int,
        help="--object-store-memory to use if starting a new cluster.")
    parser.add_argument(
        "--experiment-name",
        default="default",
        type=str,
        help="Name of the subdirectory under `local_dir` to put results in.")
    parser.add_argument(
        "--local-dir",
        default=DEFAULT_RESULTS_DIR,
        type=str,
        help="Local dir to save training results to. Defaults to '{}'.".format(
            DEFAULT_RESULTS_DIR))
    parser.add_argument(
        "--upload-dir",
        default="",
        type=str,
        help="Optional URI to sync training results to (e.g. s3://bucket).")
    parser.add_argument(
        "--resume",
        action="store_true",
        help="Whether to attempt to resume previous Tune experiments.")
    parser.add_argument(
        "--eager",
        action="store_true",
        help="Whether to attempt to enable TF eager execution.")
    parser.add_argument(
        "--trace",
        action="store_true",
        help="Whether to attempt to enable tracing for eager mode.")
    parser.add_argument(
        "--env", default=None, type=str, help="The gym environment to use.")
    parser.add_argument(
        "--queue-trials",
        action="store_true",
        help=(
            "Whether to queue trials when the cluster does not currently have "
            "enough resources to launch one. This should be set to True when "
            "running on an autoscaling cluster to enable automatic scale-up."))
    parser.add_argument(
        "-f",
        "--config-file",
        default=None,
        type=str,
        help="If specified, use config options from this file. Note that this "
        "overrides any trial-specific options set via flags above.")
    return parser


def run(args, parser):
    if args.config_file:
        with open(args.config_file) as f:
            experiments = yaml.safe_load(f)
    else:
        # Note: keep this in sync with tune/config_parser.py
        experiments = {
            args.experiment_name: {  # i.e. log to ~/ray_results/default
                "run": args.run,
                "checkpoint_freq": args.checkpoint_freq,
                "keep_checkpoints_num": args.keep_checkpoints_num,
                "checkpoint_score_attr": args.checkpoint_score_attr,
                "local_dir": args.local_dir,
                "resources_per_trial": (
                    args.resources_per_trial and
                    resources_to_json(args.resources_per_trial)),
                "stop": args.stop,
                "config": dict(args.config, env=args.env),
                "restore": args.restore,
                "num_samples": args.num_samples,
                "upload_dir": args.upload_dir,
            }
        }

    for exp in experiments.values():
        if not exp.get("run"):
            parser.error("the following arguments are required: --run")
        if not exp.get("env") and not exp.get("config", {}).get("env"):
            parser.error("the following arguments are required: --env")
        if args.eager:
            exp["config"]["eager"] = True
        if args.trace:
            if not exp["config"].get("eager"):
                raise ValueError("Must enable --eager to enable tracing.")
            exp["config"]["eager_tracing"] = True

    if args.ray_num_nodes:
        cluster = Cluster()
        for _ in range(args.ray_num_nodes):
            cluster.add_node(
                num_cpus=args.ray_num_cpus or 1,
                num_gpus=args.ray_num_gpus or 0,
                object_store_memory=args.ray_object_store_memory,
                memory=args.ray_memory,
                redis_max_memory=args.ray_redis_max_memory)
        ray.init(address=cluster.address)
    else:
        ray.init(
            address=args.ray_address,
            object_store_memory=args.ray_object_store_memory,
            memory=args.ray_memory,
            redis_max_memory=args.ray_redis_max_memory,
            num_cpus=args.ray_num_cpus,
            num_gpus=args.ray_num_gpus)
    run_experiments(
        experiments,
        scheduler=_make_scheduler(args),
        queue_trials=args.queue_trials,
        resume=args.resume)


if __name__ == "__main__":
    parser = create_parser()
    args = parser.parse_args()
    run(args, parser)