import sys
import argparse
from pathlib import Path

import torch
import torch.nn as nn
from omegaconf import OmegaConf

ROOT = Path(__file__).resolve().parent.parent.parent
sys.path.append(str(ROOT))
sys.path.append(str(ROOT / 'flow_matching'))
sys.path.append(str(ROOT / 'flow_matching/Matcha-TTS'))

from flow_matching.src.stage1.medarc_architecture import MultiSubjectConvLinearEncoder
from flow_matching.src.stage2.CFM import CFM


def _load_state_dict(path, map_location='cpu'):
    try:
        checkpoint = torch.load(path, map_location=map_location, weights_only=True)
    except TypeError:
        checkpoint = torch.load(path, map_location=map_location)

    if isinstance(checkpoint, dict) and "state_dict" in checkpoint:
        state_dict = checkpoint["state_dict"]
        if isinstance(state_dict, dict):
            return state_dict

    return checkpoint

def export_stage1(cfg):
    print('Exporting Stage 1...')
    
    subjects_list = cfg.get('subjects', [1, 2, 3, 5])
    feat_dims = (32,) 
    
    model = MultiSubjectConvLinearEncoder(
        num_subjects=len(subjects_list),
        feat_dims=feat_dims,
        **cfg.stage1.model
    )
    
    weights_path = ROOT / 'output' / 'debug_run' / 'stage1_best.pt'
    if weights_path.exists():
        state_dict = _load_state_dict(weights_path, map_location='cpu')
        model.load_state_dict(state_dict, strict=False)
        print('Loaded Stage 1 weights.')

    model.eval()

    dummy_input = [torch.randn(2, 10, 32)]
    save_path = 'stage1_model.onnx'
    
    try:
        torch.onnx.export(
            model, 
            dummy_input, 
            save_path, 
            opset_version=14, 
            input_names=['features'], 
            output_names=['embeddings']
        )
        print(f'Saved {save_path}')
    except Exception as e:
        print(f'Failed exporting Stage 1: {e}')

def export_stage2(cfg, target_dim=1000):
    print('\nExporting Stage 2...')
    
    cfm_params = cfg.stage2.cfm
    decoder_params = cfg.stage2.decoder
    model = CFM(
        feat_dim=target_dim,
        cfm_params=cfm_params,
        decoder_params=decoder_params,
    )
    
    weights_path = ROOT / 'output' / 'debug_run' / 'stage2_epoch_0.pt'
    if weights_path.exists():
        state_dict = _load_state_dict(weights_path, map_location='cpu')
        model.load_state_dict(state_dict, strict=False)
        print('Loaded Stage 2 weights.')
        
    model.eval()
    
    # Dummy input: (B, C, T) 
    B, C, T = 1, target_dim, 10
    mu = torch.randn(B, C, T)
        
    n_timesteps = torch.tensor(10)
    
    save_path = 'stage2_model.onnx'
    try:
        torch.onnx.export(
            model,
            (mu, n_timesteps),
            save_path,
            opset_version=14,
            input_names=['mu', 'n_timesteps'],
            output_names=['output']
        )
        print(f'Saved {save_path}')
    except Exception as e:
        print(f'Failed exporting Stage 2: {e}')

if __name__ == '__main__':
    config_path = ROOT / 'output' / 'debug_run' / 'config.yaml'
    if config_path.exists():
        cfg = OmegaConf.load(config_path)
    else:
        # Dummy config if config not found
        cfg = OmegaConf.create({'stage1': {'model': {}}, 'stage2': {'cfm': {}, 'decoder': {'channels': [32, 32], 'dropout': 0.0, 'attention_head_dim': 16, 'n_blocks': 1, 'num_mid_blocks': 1, 'num_heads': 2, 'act_fn': 'snakebeta', 'down_block_type': 'transformer', 'mid_block_type': 'transformer', 'up_block_type': 'transformer'}}})

    export_stage1(cfg)
    export_stage2(cfg, target_dim=1000)