import os
import numpy as np
from PIL import Image
from typing import List
from datetime import datetime

from tensorflow import keras
from tensorflow.keras import optimizers, models, mixed_precision

from wandb.keras import WandbCallback

from .dataloader import LowLightDataset
from .models import build_mirnet_model
from .losses import CharbonnierLoss
from ..commons import (
    peak_signal_noise_ratio,
    closest_number,
    init_wandb,
    download_lol_dataset,
)


class MIRNet:
    def __init__(self, experiment_name=None, wandb_api_key=None) -> None:
        self.experiment_name = experiment_name
        if wandb_api_key is not None:
            init_wandb("mirnet", experiment_name, wandb_api_key)
            self.using_wandb = True
        else:
            self.using_wandb = False

    def build_datasets(
        self,
        image_size: int = 256,
        dataset_label: str = "lol",
        apply_random_horizontal_flip: bool = True,
        apply_random_vertical_flip: bool = True,
        apply_random_rotation: bool = True,
        val_split: float = 0.2,
        batch_size: int = 16,
    ):
        if dataset_label == "lol":
            (self.low_images, self.enhanced_images), (
                self.test_low_images,
                self.test_enhanced_images,
            ) = download_lol_dataset()
        self.data_loader = LowLightDataset(
            image_size=image_size,
            apply_random_horizontal_flip=apply_random_horizontal_flip,
            apply_random_vertical_flip=apply_random_vertical_flip,
            apply_random_rotation=apply_random_rotation,
        )
        (self.train_dataset, self.val_dataset) = self.data_loader.get_datasets(
            low_light_images=self.low_images,
            enhanced_images=self.enhanced_images,
            val_split=val_split,
            batch_size=batch_size,
        )

    def build_model(
        self,
        use_mixed_precision: bool = False,
        num_recursive_residual_groups: int = 3,
        num_multi_scale_residual_blocks: int = 2,
        channels: int = 64,
        learning_rate: float = 1e-4,
        epsilon: float = 1e-3,
    ):
        if use_mixed_precision:
            policy = mixed_precision.Policy("mixed_float16")
            mixed_precision.set_global_policy(policy)
        self.model = build_mirnet_model(
            num_rrg=num_recursive_residual_groups,
            num_mrb=num_multi_scale_residual_blocks,
            channels=channels,
        )
        self.model.compile(
            optimizer=optimizers.Adam(learning_rate=learning_rate),
            loss=CharbonnierLoss(epsilon=epsilon),
            metrics=[peak_signal_noise_ratio],
        )

    def load_model(
        self, filepath, custom_objects=None, compile=True, options=None
    ) -> None:
        self.model = models.load_model(
            filepath=filepath,
            custom_objects=custom_objects,
            compile=compile,
            options=options,
        )

    def save_weights(self, filepath, overwrite=True, save_format=None, options=None):
        self.model.save_weights(
            filepath, overwrite=overwrite, save_format=save_format, options=options
        )

    def load_weights(self, filepath, by_name=False, skip_mismatch=False, options=None):
        self.model.load_weights(
            filepath, by_name=by_name, skip_mismatch=skip_mismatch, options=options
        )

    def train(self, epochs: int):
        log_dir = os.path.join(
            self.experiment_name,
            "logs",
            datetime.now().strftime("%Y%m%d-%H%M%S"),
        )
        tensorboard_callback = keras.callbacks.TensorBoard(log_dir, histogram_freq=1)
        model_checkpoint_callback = keras.callbacks.ModelCheckpoint(
            os.path.join(self.experiment_name, "weights.h5"),
            save_best_only=True,
            save_weights_only=True,
        )
        reduce_lr_callback = keras.callbacks.ReduceLROnPlateau(
            monitor="val_peak_signal_noise_ratio",
            factor=0.5,
            patience=5,
            verbose=1,
            min_delta=1e-7,
            mode="max",
        )
        callbacks = [
            tensorboard_callback,
            model_checkpoint_callback,
            reduce_lr_callback,
        ]
        if self.using_wandb:
            callbacks += [WandbCallback()]
        history = self.model.fit(
            self.train_dataset,
            validation_data=self.val_dataset,
            epochs=epochs,
            callbacks=callbacks,
        )
        return history

    def infer(
        self,
        original_image,
        image_resize_factor: float = 1.0,
        resize_output: bool = False,
    ):
        width, height = original_image.size
        target_width, target_height = (
            closest_number(width // image_resize_factor, 4),
            closest_number(height // image_resize_factor, 4),
        )
        original_image = original_image.resize(
            (target_width, target_height), Image.ANTIALIAS
        )
        image = keras.preprocessing.image.img_to_array(original_image)
        image = image.astype("float32") / 255.0
        image = np.expand_dims(image, axis=0)
        output = self.model.predict(image)
        output_image = output[0] * 255.0
        output_image = output_image.clip(0, 255)
        output_image = output_image.reshape(
            (np.shape(output_image)[0], np.shape(output_image)[1], 3)
        )
        output_image = Image.fromarray(np.uint8(output_image))
        original_image = Image.fromarray(np.uint8(original_image))
        if resize_output:
            output_image = output_image.resize((width, height), Image.ANTIALIAS)
        return output_image

    def infer_from_file(
        self,
        original_image_file: str,
        image_resize_factor: float = 1.0,
        resize_output: bool = False,
    ):
        original_image = Image.open(original_image_file)
        return self.infer(original_image, image_resize_factor, resize_output)