import os
import sys
os.environ['HF_HUB_CACHE'] = './checkpoints/hf_cache'
import torch
import torch.multiprocessing as mp
import random
import librosa
import yaml
import argparse
import torchaudio
import torchaudio.compliance.kaldi as kaldi
import glob
import time
from tqdm import tqdm
import shutil
import accelerate
from .optimizers import build_optimizer
from .data.ft_dataset import build_ft_dataloader
import hydra
from omegaconf import DictConfig

from accelerate import Accelerator
from accelerate import DistributedDataParallelKwargs
from accelerate.logging import get_logger

EXPECTED_SEEDVC_SKIPPED_KEYS = {"estimator.f0_embedder.weight", "estimator.input_pos"}

class Trainer:
    def __init__(
            self,
            config_path,
            pretrained_cfm_ckpt_path,
            pretrained_ar_ckpt_path,
            data_dir,
            run_name,
            batch_size=0,
            num_workers=0,
            steps=1000,
            save_interval=500,
            max_epochs=1000,
            train_cfm=True,
            train_ar=False,
            mixed_precision=None,
        ):
        self.config_path = config_path
        self.mixed_precision = mixed_precision

        # Load configuration
        self.config = yaml.safe_load(open(config_path))

        # Setup logging directory
        self.log_dir = os.path.join("runs", run_name)
        if not os.path.exists(self.log_dir):
            os.makedirs(self.log_dir, exist_ok=True)
        shutil.copy(config_path, os.path.join(self.log_dir, os.path.basename(config_path)))

        # Setup accelerator
        ddp_kwargs = DistributedDataParallelKwargs(find_unused_parameters=True, broadcast_buffers=False)
        self.accelerator = Accelerator(
            project_dir=self.log_dir,
            split_batches=True,
            kwargs_handlers=[ddp_kwargs],
            mixed_precision=mixed_precision
        )
        self.device = self.accelerator.device

        # Initialize training parameters
        self._init_dataloader(
            data_dir=data_dir,
            batch_size=batch_size,
            num_workers=num_workers,
            spect_params=self.config['mel_fn'],
            sr=self.config['sr'],
        )

        # Initialize models and optimizers
        self._init_models(train_cfm=train_cfm, train_ar=train_ar)

        # Load checkpoint if available
        self._load_checkpoint(pretrained_cfm_ckpt_path, pretrained_ar_ckpt_path)

        # Initialize training parameters
        self.iters = 0
        self.start_epoch = 0
        self.log_interval = 10
        self.max_steps = steps
        self.save_interval = save_interval
        self.max_epochs = max_epochs

    def _init_dataloader(self, data_dir, batch_size, num_workers, spect_params, sr):
        self.spect_params = spect_params
        self.sr = sr
        # Initialize dataloader
        self.train_dataloader = build_ft_dataloader(
            data_dir,
            spect_params,
            self.sr,
            batch_size=batch_size,
            num_workers=num_workers,
        )

    def _init_models(self, train_cfm=True, train_ar=False):
        """Initialize models and optimizers"""
        assert train_cfm or train_ar, "At least one model should be trained"
        self.train_cfm = train_cfm
        self.train_ar = train_ar
        # Initialize main model
        self._init_main_model(train_cfm=train_cfm, train_ar=train_ar)

        # Initialize optimizers
        self._init_optimizers()


    def _init_main_model(self, train_cfm=True, train_ar=False):
        """Initialize the main model"""
        with self.accelerator.main_process_first():
            cfg = DictConfig(self.config)
            self.model = hydra.utils.instantiate(cfg).to(self.device)
            for p in self.model.parameters():
                p.requires_grad = False
            if train_cfm:
                for p in self.model.cfm.parameters():
                    p.requires_grad = True
                for p in self.model.cfm_length_regulator.parameters():
                    p.requires_grad = True
            if train_ar:
                for p in self.model.ar.parameters():
                    p.requires_grad = True
                for p in self.model.ar_length_regulator.parameters():
                    p.requires_grad = True


    def _init_optimizers(self):
        """Initialize optimizers and schedulers"""
        from .optimizers import build_single_optimizer
        self.optimizer, self.scheduler = build_single_optimizer(
            self.model,
            lr=2e-5,
        )
        self.optimizer = self.accelerator.prepare(self.optimizer)
        self.scheduler = self.accelerator.prepare(self.scheduler)

    def _find_checkpoint(self, name_pattern, max_keep=1):
        """Find checkpoint files in the specified directory"""
        available_checkpoints = glob.glob(os.path.join(self.log_dir, name_pattern))
        if len(available_checkpoints) > max_keep - 1:
            # find the checkpoint that has the highest step number
            latest_checkpoint = max(
                available_checkpoints, key=lambda x: int(x.split("_")[-1].split(".")[0])
            )
            earliest_checkpoint = min(
                available_checkpoints, key=lambda x: int(x.split("_")[-1].split(".")[0])
            )
            # delete the earliest checkpoint
            if (
                    earliest_checkpoint != latest_checkpoint
                    and self.accelerator.is_main_process
                    and len(available_checkpoints) > max_keep
            ):
                os.remove(earliest_checkpoint)
                print(f"Removed {earliest_checkpoint}")
            return latest_checkpoint
        else:
            return None

    def _load_checkpoint(self, pretrained_cfm_ckpt_path, pretrained_ar_ckpt_path):
        """Load checkpoint if available"""
        cfm_checkpoint_path = pretrained_cfm_ckpt_path or self._find_checkpoint("CFM_epoch_*_step_*.pth", max_keep=1)
        ar_checkpoint_path = pretrained_ar_ckpt_path or self._find_checkpoint("AR_epoch_*_step_*.pth", max_keep=1)

        with self.accelerator.main_process_first():
            if cfm_checkpoint_path:
                print(f"Loading CFM checkpoint from {cfm_checkpoint_path}")
            if ar_checkpoint_path:
                print(f"Loading AR checkpoint from {ar_checkpoint_path}")
            self.model.load_checkpoints(cfm_checkpoint_path=cfm_checkpoint_path, ar_checkpoint_path=ar_checkpoint_path)
        self.model = self.accelerator.prepare(self.model)

    def filter_state_dict_shapes(self, params, model):
        model_state_dict = model.state_dict()
        filtered_state_dict = {
            k: v
            for k, v in params.items()
            if k in model_state_dict and v.shape == model_state_dict[k].shape
        }
        skipped_keys = set(params.keys()) - set(filtered_state_dict.keys())
        unexpected_skipped_keys = skipped_keys - EXPECTED_SEEDVC_SKIPPED_KEYS
        if unexpected_skipped_keys:
            print(
                f"Warning: Skipped loading some keys due to shape mismatch: {unexpected_skipped_keys}"
            )
        return filtered_state_dict, skipped_keys

    def train(self):
        """Main training loop"""
        for epoch in range(self.start_epoch, self.start_epoch + 1000):
            epoch_start_time = time.time()

            try:
                self.train_dataloader.sampler.set_epoch(epoch)
            except AttributeError:
                pass

            self.model.train()

            for i, batch in enumerate(tqdm(self.train_dataloader)):
                # Process batch
                self._process_batch(epoch, i, batch)
                if self.iters >= self.max_steps and self.accelerator.is_main_process:
                    print("Reached max steps, stopping training")
                    self._save_checkpoint(epoch)
                    exit()

            # Log epoch completion
            if self.accelerator.is_main_process:
                print(f"Epoch {epoch} completed in {time.time() - epoch_start_time:.2f} seconds")

            if epoch + 1 >= self.max_epochs and self.accelerator.is_main_process:
                print("Reached max epochs, stopping training")
                self._save_checkpoint(epoch)
                exit()

    def _process_batch(self, epoch, i, batch):
        """Process a single batch"""
        # Move batch to device
        waves, mels, wave_lens, mel_lens = batch
        # Resample to 16kHz for ASR models
        waves_16k = torchaudio.functional.resample(waves, self.sr, 16000)
        wave_lengths_16k = (wave_lens.float() * 16000 / self.sr).long()

        # Forward pass and loss calculation
        with self.accelerator.autocast():
            loss_ar, loss_cfm = self.model(
                waves_16k.to(self.device),
                mels.to(self.device),
                wave_lengths_16k.to(self.device),
                mel_lens.to(self.device),
                forward_ar=self.train_ar,
                forward_cfm=self.train_cfm,
            )

            loss = loss_ar + loss_cfm

            self.accelerator.backward(loss)

            grad_norm_g = torch.nn.utils.clip_grad_norm_(
                self.model.parameters(), 1000.0
            )
            self.optimizer.step()
            self.scheduler.step(self.iters)
            self.optimizer.zero_grad()

        # Log training progress
        self._log_training_progress(epoch, i, loss, loss_ar, loss_cfm, grad_norm_g)

        # Save checkpoint
        if self.iters != 0 and self.iters % self.save_interval == 0 and self.accelerator.is_main_process:
            self._save_checkpoint(epoch)

        # Increment iteration counter
        self.iters += 1

    def _log_training_progress(self, epoch, i, loss, loss_ar, loss_cfm, grad_norm_g):
        """Log training progress to tensorboard and wandb"""
        if self.iters % self.log_interval == 0 and self.accelerator.is_main_process:
            with torch.no_grad():
                cur_lr = self.scheduler.get_last_lr()[0] if i != 0 else 0

                # Log to console
                print("Epoch %d, Iteration %d, Loss: %.4f, Loss AR: %.4f, Loss CFM: %.4f, Grad Norm: %.4f, LR: %.6f"
                      % (epoch, i, loss.item(), loss_ar.item(), loss_cfm.item(), grad_norm_g, cur_lr))

    def _save_checkpoint(self, epoch):
        """Save model checkpoint"""
        print('Saving checkpoint...')
        if self.train_ar:
            state = {
                'net': {
                    'ar': self.accelerator.unwrap_model(self.model).ar.state_dict(),
                    'length_regulator': self.accelerator.unwrap_model(self.model).ar_length_regulator.state_dict(),
                },
                'iters': self.iters,
                'epoch': epoch,
            }
            save_path = os.path.join(self.log_dir, 'AR_epoch_%05d_step_%05d.pth' % (epoch, self.iters))
            torch.save(state, save_path)
            print(f"Saved AR checkpoint to {save_path}")

            # Find all checkpoints and remove old ones
            self._remove_old_checkpoints("AR_epoch_*_step_*.pth", max_keep=1)
        if self.train_cfm:
            state = {
                'net': {
                    'cfm': self.accelerator.unwrap_model(self.model).cfm.state_dict(),
                    'length_regulator': self.accelerator.unwrap_model(self.model).cfm_length_regulator.state_dict(),
                },
                'iters': self.iters,
                'epoch': epoch,
            }
            save_path = os.path.join(self.log_dir, 'CFM_epoch_%05d_step_%05d.pth' % (epoch, self.iters))
            torch.save(state, save_path)
            print(f"Saved CFM checkpoint to {save_path}")

            # Find all checkpoints and remove old ones
            self._remove_old_checkpoints("CFM_epoch_*_step_*.pth", max_keep=1)
    def _remove_old_checkpoints(self, name_pattern, max_keep=1):
        """Remove old checkpoints"""
        checkpoints = glob.glob(os.path.join(self.log_dir, name_pattern))
        if len(checkpoints) > max_keep:
            # Sort by step
            checkpoints.sort(key=lambda x: int(x.split('_')[-1].split('.')[0]))
            # Remove all except last 1
            for cp in checkpoints[:-max_keep]:
                os.remove(cp)

def main(args):
    trainer = Trainer(
        config_path=args.config,
        pretrained_cfm_ckpt_path=args.pretrained_cfm_ckpt,
        pretrained_ar_ckpt_path=args.pretrained_ar_ckpt,
        data_dir=args.dataset_dir,
        run_name=args.run_name,
        batch_size=args.batch_size,
        steps=args.max_steps,
        max_epochs=args.max_epochs,
        save_interval=args.save_every,
        num_workers=args.num_workers,
        train_cfm=args.train_cfm,
        train_ar=args.train_ar,
    )
    trainer.train()
    
if __name__ == '__main__':
    parser = argparse.ArgumentParser()
    parser.add_argument('--config', type=str, default='configs/v2/vc_wrapper.yaml')
    parser.add_argument('--pretrained-cfm-ckpt', type=str, default=None)
    parser.add_argument('--pretrained-ar-ckpt', type=str, default=None)
    parser.add_argument('--dataset-dir', type=str, default='/path/to/dataset')
    parser.add_argument('--run-name', type=str, default='my_run')
    parser.add_argument('--batch-size', type=int, default=2)
    parser.add_argument('--max-steps', type=int, default=1000)
    parser.add_argument('--max-epochs', type=int, default=1000)
    parser.add_argument('--save-every', type=int, default=500)
    parser.add_argument('--num-workers', type=int, default=0)
    parser.add_argument('--train-cfm', action='store_true', help='Train CFM model')
    parser.add_argument('--train-ar', action='store_true', help='Train AR model')
    args = parser.parse_args()
    main(args)
