import matplotlib.pyplot as plt
from matplotlib.gridspec import GridSpec
import numpy as np
from torchvision import datasets
import torch
import os
from rich.progress import track

from main import UNet, q_xt_xt_1, p_xt_1_xt, tensor_to_image


os.makedirs('plots', exist_ok=True)
os.makedirs('plots/diffusion', exist_ok=True)
os.makedirs('plots/diffusion_inverse', exist_ok=True)


DEVICE = torch.device('cuda' if torch.cuda.is_available() else 'cpu')

DIFFU_STEPS = 1000
BETA = torch.linspace(1e-4, 2e-2, DIFFU_STEPS, device=DEVICE)
BETA = torch.cat((torch.tensor([0.], device=DEVICE), BETA))
ALPHA = 1 - BETA
ALPHA_BAR = torch.cumprod(ALPHA, dim=0)

NB_BINS = 50
BIN_MIN = -4
BIN_MAX = 4


# plt.figure()
# plt.plot(BETA, label='beta')
# plt.plot(ALPHA, label='alpha')
# plt.plot(ALPHA_BAR, label='alpha_bar')
# plt.legend()
# plt.title('Alpha, Beta and Alpha_bar schedules')
# plt.savefig('plots/alpha_beta.tmp.png')


mnist = datasets.MNIST('data', train=True, download=True)
img, label = mnist[np.random.randint(0, len(mnist))]
img = np.array(img) / 255 * 2 - 1

# plt.figure()
# plt.imshow(img, cmap='gray')
# plt.title('Image')
# plt.axis('off')
# plt.savefig('plots/img.tmp.png')


# plt.figure()
# plt.hist(img.flatten(), bins=NB_BINS, range=(BIN_MIN, BIN_MAX))
# plt.yscale('log')
# plt.title('Image histogram')
# plt.savefig('plots/img_hist.tmp.png')


# def norm_dist(x, mean, std):
#     return np.exp(-0.5 * ((x - mean) / std) ** 2) / (std * np.sqrt(2 * np.pi))

# x_norm = np.linspace(BIN_MIN, BIN_MAX, 100)
# y_norm = norm_dist(x_norm, 0, 1) * 28**2 / NB_BINS * (BIN_MAX - BIN_MIN)

# fig = plt.figure(figsize=(10, 5))
# fig.suptitle('Diffusion naturelle')
# gs = GridSpec(1, 3, figure=fig)
# ax1 = fig.add_subplot(gs[0, 0])
# ax2 = fig.add_subplot(gs[0, 1:])

# plots_to_save = np.linspace(1, DIFFU_STEPS, 100).astype(int)

# xt = torch.tensor(img, device=DEVICE, dtype=torch.float32).unsqueeze(0).unsqueeze(0)
# for t in track(range(1, DIFFU_STEPS+1)):
#     xt, eps = q_xt_xt_1(xt, t)

#     if t not in plots_to_save:
#         continue

#     xt_numpy = xt.cpu().detach().numpy()[0, 0]

#     ax1.clear()
#     ax1.imshow(xt_numpy, cmap='gray')
#     ax1.set_title(f'xt at t={t:04d}')
#     ax1.axis('off')

#     ax2.clear()
#     ax2.hist(xt_numpy.flatten(), bins=NB_BINS, range=(BIN_MIN, BIN_MAX))
#     ax2.plot(x_norm, y_norm, color='red', label='N(0, 1)')
#     ax2.legend()
#     ax2.set_yscale('log')
#     ax2.set_ylim(y_norm.min(), 1e3)
#     ax2.set_title(f'xt histogram')

#     fig.savefig(f'plots/diffusion/{t:04d}.tmp.png')
# os.system('convert -delay 20 -loop 0 plots/diffusion/*.png plots/diffusion.tmp.gif')



model = UNet().to(DEVICE)
model.load_state_dict(torch.load('mnist_model.pth'))

# fig = plt.figure(figsize=(10, 5))
# fig.suptitle('Diffusion inverse')
# gs = GridSpec(1, 3, figure=fig)
# ax1 = fig.add_subplot(gs[0, 0])
# ax2 = fig.add_subplot(gs[0, 1:])

# xt = torch.randn(1, 1, 28, 28, device=DEVICE)
# vec = torch.zeros(1, 10).to(DEVICE)
# vec[0, label] = 1
# for t in track(range(DIFFU_STEPS, 0, -1)):
#     t_tensor = torch.tensor([[t]], device=DEVICE, dtype=torch.float32)
#     xt = p_xt_1_xt(model, xt, t_tensor, vec)

#     if t not in plots_to_save:
#         continue

#     xt_numpy = xt.cpu().detach().numpy()[0, 0]

#     ax1.clear()
#     ax1.imshow(xt_numpy, cmap='gray')
#     ax1.set_title(f'xt at t={t:04d}')
#     ax1.axis('off')

#     ax2.clear()
#     ax2.hist(xt_numpy.flatten(), bins=NB_BINS, range=(BIN_MIN, BIN_MAX))
#     ax2.plot(x_norm, y_norm, color='red', label='N(0, 1)')
#     ax2.legend()
#     ax2.set_yscale('log')
#     ax2.set_ylim(y_norm.min(), 1e3)
#     ax2.set_title(f'xt histogram')

#     fig.savefig(f'plots/diffusion_inverse/{t:04d}.tmp.png')
# os.system('convert -delay 20 -loop 0 -reverse plots/diffusion_inverse/*.png plots/diffusion_inverse.tmp.gif')

tpause = {150: 'xt', 20: 'mu', 50: 'xt_1'}

xT = xt = torch.randn(1, 1, 28, 28, device=DEVICE)
vec = torch.zeros(1, 10).to(DEVICE)
vec[0, label] = 1

for t in range(DIFFU_STEPS, 0, -1):
    t_tensor = torch.tensor([[t]], device=DEVICE, dtype=torch.float32)
    xt = p_xt_1_xt(model, xt, t_tensor, vec)

    if t in tpause:
        plt.figure(figsize=(5, 5))
        plt.imshow(tensor_to_image(xt[0]), cmap='gray')
        plt.axis('off')
        plt.tight_layout()
        plt.savefig(f'plots/{tpause[t]}.tmp.png')

plt.figure(figsize=(5, 5))
plt.imshow(tensor_to_image(xT[0]), cmap='gray')
plt.axis('off')
plt.tight_layout()
plt.savefig('plots/xT.tmp.png')

plt.figure(figsize=(5, 5))
plt.imshow(tensor_to_image(xt[0]), cmap='gray')
plt.axis('off')
plt.tight_layout()
plt.savefig('plots/x0.tmp.png')