# Copyright (c) 2025 Alibaba PAI and Nvidia Megatron-LM Team.
#
# 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.
"""Pretrain GPT."""

from typing import Union

import torch
import torch._dynamo

from megatron.core.enums import ModelType
from megatron.training import get_args, pretrain, print_rank_0
from megatron.training.arguments import core_transformer_config_from_args
from megatron_patch.arguments import get_patch_args

from megatron_patch.model.llama3_1.layer_specs import (
    get_gpt_layer_local_spec,
    get_gpt_layer_with_transformer_engine_spec,
)
from megatron_patch.model.llama3_1.model import GPTModel
from megatron_patch.model.llama3_1.transformer_config import LLama3TransformerConfig
from megatron_patch.tokenizer import build_tokenizer, get_tokenizer
from megatron_patch.data import train_valid_test_datasets_provider


torch._dynamo.config.suppress_errors = True


def model_provider(
    pre_process=True, post_process=True
) -> Union[GPTModel]:

    args = get_args()
    build_tokenizer(args)
    print_rank_0("building llama3.1 model ...")

    config = core_transformer_config_from_args(args, LLama3TransformerConfig)
    use_te = args.transformer_impl == "transformer_engine"

    if use_te:
        print_rank_0("building llama3.1 model in TE...")
        transformer_layer_spec = get_gpt_layer_with_transformer_engine_spec(
            args.num_experts, args.moe_grouped_gemm, args.qk_layernorm
        )
    else:
        print_rank_0("building llama3.1 model in Mcore...")
        transformer_layer_spec = get_gpt_layer_local_spec(
            args.num_experts, args.moe_grouped_gemm, args.qk_layernorm
        )

    model = GPTModel(
        config=config,
        transformer_layer_spec=transformer_layer_spec,
        vocab_size=args.padded_vocab_size,
        max_sequence_length=args.max_position_embeddings,
        pre_process=pre_process,
        post_process=post_process,
        fp16_lm_cross_entropy=args.fp16_lm_cross_entropy,
        parallel_output=True,
        share_embeddings_and_output_weights=not args.untie_embeddings_and_output_weights,
        position_embedding_type=args.position_embedding_type,
        rotary_percent=args.rotary_percent,
        rotary_base=args.rotary_base,
        rotary_scaling_config=dict(),  # The default scaling config used by llama3.1
        seq_len_interpolation_factor=args.rotary_seq_len_interpolation_factor,
    )

    return model


if __name__ == "__main__":
    from megatron_patch.template.helper import forward_step
    train_valid_test_datasets_provider.is_distributed = True

    pretrain(
        train_valid_test_datasets_provider,
        model_provider,
        ModelType.encoder_or_decoder,
        forward_step,
        extra_args_provider=get_patch_args,
    )
