from pathlib import Path

import mlx.core as mx
from huggingface_hub import snapshot_download
from mlx.utils import tree_unflatten

from mflux.weights.lora_converter import LoRAConverter
from mflux.weights.lora_util import LoraUtil
from mflux.weights.weight_util import WeightUtil


class WeightHandler:

    def __init__(
            self,
            repo_id: str | None = None,
            local_path: str | None = None,
            lora_paths: list[str] | None = None,
            lora_scales: list[float] | None = None,
    ):
        root_path = Path(local_path) if local_path else WeightHandler._download_or_get_cached_weights(repo_id)

        self.clip_encoder, _ = WeightHandler.load_clip_encoder(root_path=root_path)
        self.t5_encoder, _ = WeightHandler.load_t5_encoder(root_path=root_path)
        self.vae, _ = WeightHandler.load_vae(root_path=root_path)
        self.transformer, self.quantization_level = WeightHandler.load_transformer(root_path=root_path)

        if lora_paths:
            LoraUtil.apply_loras(self.transformer, lora_paths, lora_scales)

    @staticmethod
    def load_clip_encoder(root_path: Path) -> (dict, int):
        weights, quantization_level = WeightHandler._get_weights("text_encoder", root_path)
        return weights, quantization_level

    @staticmethod
    def load_t5_encoder(root_path: Path) -> (dict, int):
        weights, quantization_level = WeightHandler._get_weights("text_encoder_2", root_path)

        # Quantized weights (i.e. ones exported from this project) don't need any post-processing.
        if quantization_level is not None:
            return weights, quantization_level

        # Reshape and process the huggingface weights
        weights["final_layer_norm"] = weights["encoder"]["final_layer_norm"]
        for block in weights["encoder"]["block"]:
            attention = block["layer"][0]
            ff = block["layer"][1]
            block.pop("layer")
            block["attention"] = attention
            block["ff"] = ff

        weights["t5_blocks"] = weights["encoder"]["block"]

        # Only the first layer has the weights for "relative_attention_bias", we duplicate them here to keep code simple
        relative_attention_bias = weights["t5_blocks"][0]["attention"]["SelfAttention"]["relative_attention_bias"]
        for block in weights["t5_blocks"][1:]:
            block["attention"]["SelfAttention"]["relative_attention_bias"] = relative_attention_bias

        weights.pop("encoder")
        return weights, quantization_level

    @staticmethod
    def load_transformer(root_path: Path | None = None, lora_path: str | None = None) -> (dict, int):
        weights, quantization_level = WeightHandler._get_weights("transformer", root_path, lora_path)

        if lora_path:
            if 'transformer' not in weights:
                weights = LoRAConverter.load_weights(lora_path)
            weights = weights["transformer"]

        # Quantized weights (i.e. ones exported from this project) don't need any post-processing.
        if quantization_level is not None:
            return weights, quantization_level

        # Reshape and process the huggingface weights
        if "transformer_blocks" in weights:
            for block in weights["transformer_blocks"]:
                if block.get("ff") is not None:
                    block["ff"] = {
                        "linear1": block["ff"]["net"][0]["proj"],
                        "linear2": block["ff"]["net"][2]
                    }
                if block.get("ff_context") is not None:
                    block["ff_context"] = {
                        "linear1": block["ff_context"]["net"][0]["proj"],
                        "linear2": block["ff_context"]["net"][2]
                    }
        return weights, quantization_level

    @staticmethod
    def load_vae(root_path: Path) -> (dict, int):
        weights, quantization_level = WeightHandler._get_weights("vae", root_path)

        # Quantized weights (i.e. ones exported from this project) don't need any post-processing.
        if quantization_level is not None:
            return weights, quantization_level

        # Reshape and process the huggingface weights
        weights['decoder']['conv_in'] = {'conv2d': weights['decoder']['conv_in']}
        weights['decoder']['conv_out'] = {'conv2d': weights['decoder']['conv_out']}
        weights['decoder']['conv_norm_out'] = {'norm': weights['decoder']['conv_norm_out']}
        weights['encoder']['conv_in'] = {'conv2d': weights['encoder']['conv_in']}
        weights['encoder']['conv_out'] = {'conv2d': weights['encoder']['conv_out']}
        weights['encoder']['conv_norm_out'] = {'norm': weights['encoder']['conv_norm_out']}
        return weights, quantization_level

    @staticmethod
    def _get_weights(model_name: str, root_path: Path | None = None, lora_path: str | None = None) -> (dict, int):
        weights = []
        quantization_level = None

        if root_path is not None:
            for file in sorted(root_path.glob(model_name + "/*.safetensors")):
                quantization_level = mx.load(str(file), return_metadata=True)[1].get("quantization_level")
                weight = list(mx.load(str(file)).items())
                weights.extend(weight)

        if lora_path and root_path is None:
            weight = list(mx.load(lora_path).items())
            weights.extend(weight)

        # Non huggingface weights (i.e. ones exported from this project) don't need any reshaping.
        if quantization_level is not None:
            return tree_unflatten(weights), quantization_level

        # Huggingface weights needs to be reshaped
        weights = [WeightUtil.reshape_weights(k, v) for k, v in weights]
        weights = WeightUtil.flatten(weights)
        unflatten = tree_unflatten(weights)
        return unflatten, quantization_level

    @staticmethod
    def _download_or_get_cached_weights(repo_id: str) -> Path:
        return Path(
            snapshot_download(
                repo_id=repo_id,
                allow_patterns=[
                    "text_encoder/*.safetensors",
                    "text_encoder_2/*.safetensors",
                    "transformer/*.safetensors",
                    "vae/*.safetensors",
                ]
            )
        )