########################################################################################################
# The RWKV Language Model - https://github.com/BlinkDL/RWKV-LM
########################################################################################################

if __name__ == "__main__":
    print("\n!!! NOTE: THIS IS STILL WIP (and a bit slower than RWKV-4) !!!\n")
    import os, warnings, math, datetime
    import numpy as np
    from argparse import ArgumentParser
    import torch
    import deepspeed
    import pytorch_lightning as pl
    from pytorch_lightning import Trainer
    from pytorch_lightning import seed_everything
    from pytorch_lightning.utilities import rank_zero_info, rank_zero_only
    from pytorch_lightning.callbacks import TQDMProgressBar
    from pytorch_lightning import Callback

    seed_everything(42)
    np.set_printoptions(precision=4, suppress=True, linewidth=200)
    warnings.filterwarnings("ignore", ".*Consider increasing the value of the `num_workers` argument*")
    warnings.filterwarnings("ignore", ".*The progress bar already tracks a metric with the*")

    ########################################################################################################

    parser = ArgumentParser()
    parser = Trainer.add_argparse_args(parser)

    parser.add_argument("--load_model", default="", type=str)
    parser.add_argument("--wandb", default="", type=str)
    parser.add_argument("--proj_dir", default="out", type=str)

    parser.add_argument("--data_file", default="", type=str)
    parser.add_argument("--data_type", default="utf-8", type=str)
    parser.add_argument("--vocab_size", default=0, type=int)

    parser.add_argument("--ctx_len", default=1024, type=int)
    parser.add_argument("--epoch_steps", default=1000, type=int)
    parser.add_argument("--epoch_count", default=500, type=int)
    parser.add_argument("--epoch_begin", default=0, type=int)
    parser.add_argument("--epoch_save", default=5, type=int)

    parser.add_argument("--micro_bsz", default=12, type=int)
    parser.add_argument("--n_layer", default=6, type=int)
    parser.add_argument("--n_embd", default=512, type=int)
    parser.add_argument("--pre_ffn", default=0, type=int)
    parser.add_argument("--head_qk", default=0, type=int)

    parser.add_argument("--lr_init", default=6e-4, type=float)
    parser.add_argument("--lr_final", default=1e-5, type=float)
    parser.add_argument("--warmup_steps", default=0, type=int)
    parser.add_argument("--beta1", default=0.9, type=float)
    parser.add_argument("--beta2", default=0.99, type=float)
    parser.add_argument("--adam_eps", default=1e-8, type=float)

    parser.add_argument("--grad_cp", default=0, type=int)
    parser.add_argument("--data_workers", default=1, type=int)

    args = parser.parse_args()

    args.enable_checkpointing = False
    args.logger = False
    args.gradient_clip_val = 1.0
    args.num_sanity_val_steps = 0
    args.check_val_every_n_epoch = int(1e20)
    args.auto_select_gpus = True
    args.log_every_n_steps = int(1e20)
    args.max_epochs = -1  # continue forever
    args.betas = (args.beta1, args.beta2)

    samples_per_epoch = args.epoch_steps * int(args.devices) * args.micro_bsz
    tokens_per_epoch = samples_per_epoch * args.ctx_len
    rank_zero_info(
        f"""
############################################################################
#
# RWKV-4 {args.precision.upper()} on {args.devices} x {args.accelerator.upper()} {args.strategy.upper()} {'with grad_cp' if args.grad_cp > 0 else ''}
#
# Data = {args.data_file} ({args.data_type}), ProjDir = {args.proj_dir}
#
# Epoch = {args.epoch_begin} to {args.epoch_begin + args.epoch_count - 1} (will continue afterwards), save every {args.epoch_save} epoch
#
# Each "epoch" = {args.epoch_steps} steps, {samples_per_epoch} samples, {tokens_per_epoch} tokens
#
# Model = {args.n_layer} n_layer, {args.n_embd} n_embd, {args.ctx_len} ctx_len
#
# Adam = lr {args.lr_init} to {args.lr_final}, warmup {args.warmup_steps} steps, β {args.betas}, eps {args.adam_eps}
#
# torch {torch.__version__}, recommend 1.12.1+cu116 or newer
# deepspeed {deepspeed.__version__}, recommend 0.7.2 or newer
# pytorch_lightning {pl.__version__}, recommend 1.7.4 or newer
#
############################################################################
"""
    )
    rank_zero_info(str(vars(args)) + "\n")

    if not os.path.exists(args.proj_dir):
        os.makedirs(args.proj_dir)

    assert args.data_type in ["utf-8", "utf-16le", "numpy", "binidx"]
    assert len(args.data_file) > 0

    if args.lr_final == 0 or args.lr_init == 0:
        rank_zero_info("\n\nNote: lr_final = 0 or lr_init = 0. Using linear LR schedule.\n\n")

    assert args.precision in ["fp32", "tf32", "fp16", "bf16"]
    os.environ["RWKV_FLOAT_MODE"] = args.precision
    if args.precision == "fp32":
        rank_zero_info("\n\nNote: you are using fp32 (very slow). Try bf16 / tf32 for faster training.\n\n")
    if args.precision == "fp16":
        rank_zero_info("\n\nNote: you are using fp16 (might overflow). Try bf16 / tf32 for stable training.\n\n")

    import torch

    torch.backends.cudnn.benchmark = True
    if args.precision == "fp32":
        torch.backends.cudnn.allow_tf32 = False
        torch.backends.cuda.matmul.allow_tf32 = False
    else:
        torch.backends.cudnn.allow_tf32 = True
        torch.backends.cuda.matmul.allow_tf32 = True

    if "32" in args.precision:
        args.precision = 32
    elif args.precision == "fp16":
        args.precision = 16
    else:
        args.precision = "bf16"

    ########################################################################################################

    class train_callback(pl.Callback):
        def __init__(self, args):
            super().__init__()
            self.args = args

        def on_train_batch_start(self, trainer, pl_module, batch, batch_idx):
            args = self.args
            g_step = trainer.global_step

            # logging
            if trainer.global_rank == 0:
                if g_step == 0:
                    trainer.my_log = open(args.proj_dir + "/train_log.txt", "a")
                    trainer.my_log.write(f"NEW RUN {datetime.datetime.now()}\n{vars(self.args)}\n")
                    trainer.my_log.flush()
                    if len(args.wandb) > 0:
                        print("Login to wandb...")
                        import wandb

                        model_name = str(args.vocab_size) + "-" + str(args.ctx_len) + "-" + str(args.n_layer) + "-" + str(args.n_embd)
                        wandb.init(
                            project=args.wandb,
                            name=model_name + "-" + datetime.datetime.today().strftime("%Y-%m-%d-%H-%M-%S"),
                            config=args,
                            save_code=False,
                        )
                        trainer.my_wandb = wandb

            # LR schedule
            w_step = args.warmup_steps
            if g_step < w_step:
                lr = args.lr_init * (g_step / w_step)
            else:
                progress = (g_step - w_step) / (args.epoch_count * args.epoch_steps - w_step - 1)
                progress = min(1, max(0, progress))

                if args.lr_final == 0 or args.lr_init == 0:  # linear decay
                    lr = args.lr_init + (args.lr_final - args.lr_init) * progress
                else:  # exp decay
                    lr = args.lr_init * math.exp(math.log(args.lr_final / args.lr_init) * pow(progress, 1))

            for param_group in trainer.optimizers[0].param_groups:
                param_group["lr"] = lr

            trainer.my_lr = lr
            # rank_zero_info(f"{g_step} {lr}")

        def on_train_batch_end(self, trainer, pl_module, outputs, batch, batch_idx):
            args = self.args
            # logging
            if trainer.global_rank == 0:
                if len(args.wandb) > 0:
                    trainer.my_wandb.log(
                        {"loss": trainer.my_loss, "lr": trainer.my_lr},
                        step=trainer.global_step,
                    )

        def on_train_epoch_end(self, trainer, pl_module):
            args = self.args
            if trainer.global_rank == 0:
                if trainer.current_epoch % args.epoch_save == 0 or trainer.current_epoch == args.epoch_count - 1:
                    torch.save(
                        pl_module.state_dict(),
                        f"{args.proj_dir}/rwkv-{args.epoch_begin + trainer.current_epoch}.pth",
                    )
                trainer.my_log.write(f"{args.epoch_begin + trainer.current_epoch} {trainer.my_epoch_loss:.6f} {math.exp(trainer.my_epoch_loss):.4f} {trainer.my_lr:.8f} {datetime.datetime.now()} {trainer.current_epoch}\n")
                trainer.my_log.flush()

    @rank_zero_only
    def generate_init_weight(model, temp_name):
        try:
            os.remove(temp_name)
        except:
            pass
        mm = model.generate_init_weight()
        print(f"Saving to {temp_name}...")
        torch.save(mm, temp_name)

    ########################################################################################################

    from torch.utils.data import DataLoader
    from src.dataset import MyDataset
    from src.model import RWKV

    train_data = MyDataset(args)
    args.vocab_size = train_data.vocab_size

    model = RWKV(args)

    if len(args.load_model) == 0:
        args.load_model = f"{args.proj_dir}/rwkv-init.pth"  # init weights to tmp file
        generate_init_weight(model, args.load_model)

    print(f"\nLoading {args.load_model}...\n")
    load_dict = torch.load(args.load_model, map_location="cpu")
    model.load_state_dict(load_dict)

    trainer = Trainer.from_argparse_args(
        args,
        callbacks=[train_callback(args)],
    )

    train_loader = DataLoader(train_data, batch_size=args.micro_bsz, num_workers=args.data_workers)
    trainer.fit(model, train_loader)