import gradio as gr
import numpy as np
import tensorflow as tf
from tensorflow import keras
from huggingface_hub import from_pretrained_keras

result_prefix = "paris_generated"

# Weights of the different loss components
total_variation_weight = 1e-6
style_weight = 1e-6
content_weight = 2.5e-8

# Dimensions of the generated picture.
width, height = keras.preprocessing.image.load_img(base_image_path).size
img_nrows = 400
img_ncols = int(width * img_nrows / height)

def preprocess_image(image_path):
    # Util function to open, resize and format pictures into appropriate tensors
    img = keras.preprocessing.image.load_img(
        image_path, target_size=(img_nrows, img_ncols)
    )
    img = keras.preprocessing.image.img_to_array(img)
    img = np.expand_dims(img, axis=0)
    img = vgg19.preprocess_input(img)
    return tf.convert_to_tensor(img)

def deprocess_image(x):
    # Util function to convert a tensor into a valid image
    x = x.reshape((img_nrows, img_ncols, 3))
    # Remove zero-center by mean pixel
    x[:, :, 0] += 103.939
    x[:, :, 1] += 116.779
    x[:, :, 2] += 123.68
    # 'BGR'->'RGB'
    x = x[:, :, ::-1]
    x = np.clip(x, 0, 255).astype("uint8")
    return x

# The gram matrix of an image tensor (feature-wise outer product)

def gram_matrix(x):
    x = tf.transpose(x, (2, 0, 1))
    features = tf.reshape(x, (tf.shape(x)[0], -1))
    gram = tf.matmul(features, tf.transpose(features))
    return gram

# The "style loss" is designed to maintain
# the style of the reference image in the generated image.
# It is based on the gram matrices (which capture style) of
# feature maps from the style reference image
# and from the generated image

def style_loss(style, combination):
    S = gram_matrix(style)
    C = gram_matrix(combination)
    channels = 3
    size = img_nrows * img_ncols
    return tf.reduce_sum(tf.square(S - C)) / (4.0 * (channels ** 2) * (size ** 2))

# An auxiliary loss function
# designed to maintain the "content" of the
# base image in the generated image

def content_loss(base, combination):
    return tf.reduce_sum(tf.square(combination - base))

# The 3rd loss function, total variation loss,
# designed to keep the generated image locally coherent

def total_variation_loss(x):
    a = tf.square(
        x[:, : img_nrows - 1, : img_ncols - 1, :] - x[:, 1:, : img_ncols - 1, :]
    )
    b = tf.square(
        x[:, : img_nrows - 1, : img_ncols - 1, :] - x[:, : img_nrows - 1, 1:, :]
    )
    return tf.reduce_sum(tf.pow(a + b, 1.25))

def compute_loss(combination_image, base_image, style_reference_image):
    input_tensor = tf.concat(
        [base_image, style_reference_image, combination_image], axis=0
    )
    features = feature_extractor(input_tensor)

    # Initialize the loss
    loss = tf.zeros(shape=())

    # Add content loss
    layer_features = features[content_layer_name]
    base_image_features = layer_features[0, :, :, :]
    combination_features = layer_features[2, :, :, :]
    loss = loss + content_weight * content_loss(
        base_image_features, combination_features
    )
    # Add style loss
    for layer_name in style_layer_names:
        layer_features = features[layer_name]
        style_reference_features = layer_features[1, :, :, :]
        combination_features = layer_features[2, :, :, :]
        sl = style_loss(style_reference_features, combination_features)
        loss += (style_weight / len(style_layer_names)) * sl

    # Add total variation loss
    loss += total_variation_weight * total_variation_loss(combination_image)
    return loss

# Build a VGG19 model loaded with pre-trained ImageNet weights
# model = vgg19.VGG19(weights="imagenet", include_top=False)
model = from_pretrained_keras("rushic24/keras-VGG19")

# Get the symbolic outputs of each "key" layer (we gave them unique names).
outputs_dict = dict([(layer.name, layer.output) for layer in model.layers])

# Set up a model that returns the activation values for every layer in
# VGG19 (as a dict).
feature_extractor = keras.Model(inputs=model.inputs, outputs=outputs_dict)

# List of layers to use for the style loss.
style_layer_names = [
    "block1_conv1",
    "block2_conv1",
    "block3_conv1",
    "block4_conv1",
    "block5_conv1",
]
# The layer to use for the content loss.
content_layer_name = "block5_conv2"

@tf.function
def compute_loss_and_grads(combination_image, base_image, style_reference_image):
    with tf.GradientTape() as tape:
        loss = compute_loss(combination_image, base_image, style_reference_image)
    grads = tape.gradient(loss, combination_image)
    return loss, grads

optimizer = keras.optimizers.SGD(
    keras.optimizers.schedules.ExponentialDecay(
        initial_learning_rate=100.0, decay_steps=100, decay_rate=0.96
    )
)

def get_imgs(base_image_path, style_reference_image_path):
  base_image = preprocess_image(base_image_path)
  style_reference_image = preprocess_image(style_reference_image_path)
  combination_image = tf.Variable(preprocess_image(base_image_path))

  iterations = 400
  for i in range(1, iterations + 1):
      loss, grads = compute_loss_and_grads(combination_image, base_image, style_reference_image)
      optimizer.apply_gradients([(grads, combination_image)])
      if i % 100 == 0:
          print("Iteration %d: loss=%.2f" % (i, loss))
          img = deprocess_image(combination_image.numpy())

  return img


title = "Neural style transfer"
description = "Gradio Demo for Neural style transfer. To use it, simply upload a base image and a style image"

content  = gr.inputs.Image(shape=None, image_mode="RGB", invert_colors=False, source="upload", tool="editor", type="filepath", label=None, optional=False)
style  = gr.inputs.Image(shape=None, image_mode="RGB", invert_colors=False, source="upload", tool="editor", type="filepath", label=None, optional=False)
gr.Interface(get_imgs, inputs=[content, style], outputs=["image"], 
             title=title,
             description=description,
             examples=[["base.jpg", "style.jpg"]]).launch(enable_queue=True)