"""
Training script for MHD64 dataset using neural operators.

This script trains a neural operator on the 3D magnetohydrodynamics (MHD)
dataset with 64x64x64 resolution. The model learns to predict the next time step
in the MHD simulation, supporting both next-step prediction and autoregressive
evaluation modes.
"""

import sys

from configmypy import ConfigPipeline, YamlConfig, ArgparseConfig
from pathlib import Path
import torch

from torch.utils.data import DataLoader, DistributedSampler
import wandb

from neuralop import H1Loss, LpLoss, Trainer, get_model
from neuralop.data.datasets.the_well_dataset import MHD64Dataset
from neuralop.data.transforms.data_processors import MGPatchingDataProcessor
from neuralop.training import setup, AdamW
from neuralop.mpu.comm import get_local_rank
from neuralop.utils import get_wandb_api_key, count_model_params

# Configuration setup
config_name = "default"
from zencfg import make_config_from_cli
import sys

sys.path.insert(0, "../")
from config.the_well.mhd_64_config import Default

config = make_config_from_cli(Default)
config = config.to_dict()

# Distributed training setup, if enabled
device, is_logger = setup(config)

# Set up WandB logging
wandb_args = None
if config.wandb.log and is_logger:
    wandb.login(key=get_wandb_api_key())
    if config.wandb.name:
        wandb_name = config.wandb.name
    else:
        wandb_name = "_".join(
            f"{var}"
            for var in [
                config.model.model_arch,
                config.model.n_layers,
                config.model.n_modes,
                config.model.hidden_channels,
            ]
        )
    wandb_args = dict(
        config=config,
        name=wandb_name,
        group=config.wandb.group,
        project=config.wandb.project,
        entity=config.wandb.entity,
    )
    if config.wandb.sweep:
        for key in wandb.config.keys():
            config.params[key] = wandb.config[key]
    wandb.init(**wandb_args)

# Make sure we only print information when needed
config.verbose = config.verbose and is_logger

# Print configuration details
if config.verbose and is_logger:
    print(f"##### CONFIG #####\n\n{config}\n")
    sys.stdout.flush()

# Load the MHD64 dataset
dataset = MHD64Dataset(
    root_dir=Path(config.data.root).expanduser(),
    train_task="next_step",
    eval_tasks=["next_step", "autoregression"],
    first_only=True,
)

# Print dataset metadata
print(dataset.train_db.metadata.n_steps_per_trajectory)

# Create data loaders
train_loader = DataLoader(dataset.train_db, batch_size=config.data.batch_size)

test_loaders = {}
for mode, db in dataset.test_dbs.items():
    test_loaders[mode] = DataLoader(db, batch_size=config.data.test_batch_size)

# Get data processor from dataset
data_processor = dataset.data_processor
print(data_processor)

# Model initialization
model = get_model(config)

# convert dataprocessor to an MGPatchingDataprocessor if patching levels > 0
if config.patching.levels > 0:
    data_processor = MGPatchingDataProcessor(
        model=model,
        in_normalizer=data_processor.normalizer,
        out_normalizer=data_processor.normalizer,
        padding_fraction=config.patching.padding,
        stitching=config.patching.stitching,
        levels=config.patching.levels,
        use_distributed=config.distributed.use_distributed,
        device=device,
    )

# Reconfigure DataLoaders to use a DistributedSampler
# if in distributed data parallel mode
"""if config.distributed.use_distributed:
    train_sampler = DistributedSampler(dataset.train_db, rank=get_local_rank())
    train_loader = DataLoader(dataset=dataset.train_db,
                              batch_size=config.data.batch_size,
                              sampler=train_sampler)
    for (res, loader), batch_size in zip(test_loaders.items(), config.data.test_batch_sizes):
        
        test_db = loader.dataset
        test_sampler = DistributedSampler(test_db, rank=get_local_rank())
        test_loaders[res] = DataLoader(dataset=test_db,
                              batch_size=batch_size,
                              shuffle=False,
                              sampler=test_sampler)"""
# Create the optimizer
optimizer = AdamW(
    model.parameters(),
    lr=config.opt.learning_rate,
    weight_decay=config.opt.weight_decay,
)

if config.opt.scheduler == "ReduceLROnPlateau":
    scheduler = torch.optim.lr_scheduler.ReduceLROnPlateau(
        optimizer,
        factor=config.opt.gamma,
        patience=config.opt.scheduler_patience,
        mode="min",
    )
elif config.opt.scheduler == "CosineAnnealingLR":
    scheduler = torch.optim.lr_scheduler.CosineAnnealingLR(
        optimizer, T_max=config.opt.scheduler_T_max
    )
elif config.opt.scheduler == "StepLR":
    scheduler = torch.optim.lr_scheduler.StepLR(
        optimizer, step_size=config.opt.step_size, gamma=config.opt.gamma
    )
else:
    raise ValueError(f"Got scheduler={config.opt.scheduler}")


# Loss function configuration
l2loss = LpLoss(d=3, p=2)
h1loss = H1Loss(d=3)
if config.opt.training_loss == "l2":
    train_loss = l2loss
elif config.opt.training_loss == "h1":
    train_loss = h1loss
else:
    raise ValueError(
        f"Got training_loss={config.opt.training_loss}"
        f'but expected one of ["l2", "h1"]'
    )
eval_losses = {"h1": h1loss, "l2": l2loss}

if config.verbose and is_logger:
    print("\n### MODEL ###\n", model)
    print("\n### OPTIMIZER ###\n", optimizer)
    print("\n### SCHEDULER ###\n", scheduler)
    print("\n### LOSSES ###")
    print(f"\n * Train: {train_loss}")
    print(f"\n * Test: {eval_losses}")
    print(f"\n### Beginning Training...\n")
    sys.stdout.flush()

trainer = Trainer(
    model=model,
    n_epochs=config.opt.n_epochs,
    device=device,
    data_processor=data_processor,
    mixed_precision=config.opt.mixed_precision,
    wandb_log=config.wandb.log,
    eval_interval=config.opt.eval_interval,
    log_output=config.wandb.log_output,
    use_distributed=config.distributed.use_distributed,
    verbose=config.verbose and is_logger,
)

# Log model parameter count
if is_logger:
    n_params = count_model_params(model)

    if config.verbose:
        print(f"\nn_params: {n_params}")
        sys.stdout.flush()

    if config.wandb.log:
        to_log = {"n_params": n_params}
        if config.n_params_baseline is not None:
            to_log["n_params_baseline"] = (config.n_params_baseline,)
            to_log["compression_ratio"] = (config.n_params_baseline / n_params,)
            to_log["space_savings"] = 1 - (n_params / config.n_params_baseline)
        wandb.log(to_log, commit=False)
        wandb.watch(model)

# Start training process with autoregressive evaluation
trainer.train(
    train_loader=train_loader,
    test_loaders=test_loaders,
    eval_modes={"autoregression": "autoregression"},
    optimizer=optimizer,
    scheduler=scheduler,
    regularizer=False,
    training_loss=train_loss,
    eval_losses=eval_losses,
)

# Finalize WandB logging
if config.wandb.log and is_logger:
    wandb.finish()