# SPDX-FileCopyrightText: Copyright (c) 2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
# SPDX-License-Identifier: Apache-2.0
#
# 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.

import argparse
import importlib
import os

import torch.distributed as dist
from loguru import logger as logging
from omegaconf import OmegaConf

from cosmos_predict1.diffusion.config.config import Config
from cosmos_predict1.utils import log, misc
from cosmos_predict1.utils.config_helper import get_config_module, override
from cosmos_predict1.utils.lazy_config import instantiate
from cosmos_predict1.utils.lazy_config.lazy import LazyConfig
from cosmos_predict1.utils.parallel_state_helper import is_tp_cp_pp_rank0


@misc.timer("instantiate model")
def instantiate_model(config: Config, trainer) -> None:
    misc.set_random_seed(seed=config.trainer.seed, by_rank=False)
    config.model_obj.config = config.model
    if getattr(config.model, "fsdp_enabled", False):
        assert config.trainer.distributed_parallelism == "fsdp", "FSDP model is only supported with FSDP trainer"
        log.critical("FSDP enabled")
        config.model_obj.fsdp_checkpointer = trainer.checkpointer
        model = instantiate(config.model_obj)
        config.model_obj.fsdp_checkpointer = None
    else:
        model = instantiate(config.model_obj)
    config.model_obj.config = None
    misc.set_random_seed(seed=config.trainer.seed, by_rank=True)
    return model


def destroy_distributed():
    log.info("Destroying distributed environment...")
    if dist.is_available() and dist.is_initialized():
        try:
            dist.destroy_process_group()
        except ValueError as e:
            print(f"Error destroying default process group: {e}")


@logging.catch(reraise=True)
def launch(config: Config, args: argparse.Namespace) -> None:
    # Check that the config is valid
    config.validate()
    # Freeze the config so developers don't change it during training.
    config.freeze()  # type: ignore
    trainer = config.trainer.type(config)
    # # Setup the miscellaneous stuff for reproducibility.
    # log_reproducible_setup(config, args)
    # Create the model
    model = instantiate_model(config, trainer)
    model.on_model_init_end()
    # Create the dataloaders.
    if args.mp0_only_dl:
        log.critical(
            "Using only tp_cp_pp_rank0 dataloader for faster dataloading! Make sure val dl is mock and mock data has same keys as real data."
        )
        raise NotImplementedError(
            "mp0_only_dl is not implemented correctly! Please revisit this code and propose a more robust impl that raise error timely! It does not do necessary check before training to confirm it can work with image / video data. Current impl is problematic for image training."
        )
    if is_tp_cp_pp_rank0() or not args.mp0_only_dl:
        dataloader_train = instantiate(config.dataloader_train)
    else:
        dataloader_train = instantiate(config.dataloader_val)
    dataloader_val = instantiate(config.dataloader_val)
    # Start training
    trainer.train(
        model,
        dataloader_train,
        dataloader_val,
    )
    destroy_distributed()


if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="Training")
    parser.add_argument(
        "--config",
        default="cosmos_predict1/diffusion/posttrain/config/config.py",
        help="Path to the config file",
    )
    parser.add_argument(
        "opts",
        help="""
Modify config options at the end of the command. For Yacs configs, use
space-separated "PATH.KEY VALUE" pairs.
For python-based LazyConfig, use "path.key=value".
        """.strip(),
        default=None,
        nargs=argparse.REMAINDER,
    )
    parser.add_argument(
        "--dryrun",
        action="store_true",
        help="Do a dry run without training. Useful for debugging the config.",
    )
    parser.add_argument(
        "--mp0_only_dl",
        action="store_true",
        help="Use only model parallel rank 0 dataloader for faster dataloading! Make sure mock data has same keys as real data.",
    )
    args = parser.parse_args()
    config_module = get_config_module(args.config)
    config = importlib.import_module(config_module).make_config()
    config = override(config, args.opts)
    if args.dryrun:
        os.makedirs(config.job.path_local, exist_ok=True)
        LazyConfig.save_yaml(config, f"{config.job.path_local}/config.yaml")
        print(OmegaConf.to_yaml(OmegaConf.load(f"{config.job.path_local}/config.yaml")))
        print(f"{config.job.path_local}/config.yaml")
    else:
        # Launch the training job.
        launch(config, args)