import tensorflow as tf
import numpy as np
import matplotlib.pyplot as plt
from tensorflow.keras.layers import Conv2D, Conv2DTranspose, LeakyReLU, BatchNormalization, Input, Concatenate
from tensorflow.keras.models import Model

def build_generator():
    inputs = Input(shape=(256, 256, 3))
    x = Conv2D(64, 4, strides=2, padding='same', activation='relu')(inputs)
    x = BatchNormalization()(x)
    x = Conv2D(128, 4, strides=2, padding='same', activation='relu')(x)
    x = BatchNormalization()(x)
    x = Conv2D(256, 4, strides=2, padding='same', activation='relu')(x)
    x = BatchNormalization()(x)
    x = Conv2D(512, 4, strides=2, padding='same', activation='relu')(x)
    x = BatchNormalization()(x)
    x = Conv2DTranspose(256, 4, strides=2, padding='same', activation='relu')(x)
    x = BatchNormalization()(x)
    x = Conv2DTranspose(128, 4, strides=2, padding='same', activation='relu')(x)
    x = BatchNormalization()(x)
    x = Conv2DTranspose(64, 4, strides=2, padding='same', activation='relu')(x)
    x = BatchNormalization()(x)
    outputs = Conv2D(3, 4, strides=1, padding='same', activation='tanh')(x)
    return Model(inputs, outputs)

def build_discriminator():
    inputs = Input(shape=(256, 256, 3))
    x = Conv2D(64, 4, strides=2, padding='same', activation='relu')(inputs)
    x = LeakyReLU(alpha=0.2)(x)
    x = Conv2D(128, 4, strides=2, padding='same', activation='relu')(x)
    x = LeakyReLU(alpha=0.2)(x)
    x = Conv2D(256, 4, strides=2, padding='same', activation='relu')(x)
    x = LeakyReLU(alpha=0.2)(x)
    x = Conv2D(512, 4, strides=2, padding='same', activation='relu')(x)
    x = LeakyReLU(alpha=0.2)(x)
    x = Conv2D(1, 4, strides=1, padding='same')(x)
    return Model(inputs, x)

# Hyperparameters
epochs = 20
batch_size = 1

# Load dataset (example)
def load_data():
    # Placeholder function to load dataset
    return np.random.rand(10, 256, 256, 3), np.random.rand(10, 256, 256, 3)

# Initialize models
generator = build_generator()
discriminator = build_discriminator()

# Compile models
generator.compile(optimizer=tf.keras.optimizers.Adam(1e-4))
discriminator.compile(optimizer=tf.keras.optimizers.Adam(1e-4))

# Training loop
for epoch in range(epochs):
    real_images, target_images = load_data()
    fake_images = generator.predict(real_images)
    
    # Train Discriminator
    d_loss_real = discriminator.train_on_batch(target_images, np.ones((batch_size, 256, 256, 1)))
    d_loss_fake = discriminator.train_on_batch(fake_images, np.zeros((batch_size, 256, 256, 1)))
    
    # Train Generator
    g_loss = generator.train_on_batch(real_images, np.ones((batch_size, 256, 256, 1)))
    
    print(f'Epoch [{epoch+1}/{epochs}], D Loss Real: {d_loss_real}, D Loss Fake: {d_loss_fake}, G Loss: {g_loss}')
    
    if (epoch + 1) % 5 == 0:
        output_images = generator.predict(real_images)
        for i in range(batch_size):
            plt.imshow(output_images[i])
            plt.axis('off')
            plt.savefig(f'pix2pix_image_{epoch+1}_{i}.png')
            plt.close()