import os
import math
import time
import datetime
from functools import reduce

import matplotlib
matplotlib.use('Agg')
import matplotlib.pyplot as plt

import numpy as np
import scipy.misc as misc
import cv2
import torch
import torch.optim as optim
import torch.optim.lr_scheduler as lrs

class timer():
    def __init__(self):
        self.acc = 0
        self.tic()

    def tic(self):
        self.t0 = time.time()

    def toc(self):
        return time.time() - self.t0

    def hold(self):
        self.acc += self.toc()

    def release(self):
        ret = self.acc
        self.acc = 0

        return ret

    def reset(self):
        self.acc = 0

class checkpoint():
    def __init__(self, args):
        self.args = args
        self.ok = True
        self.log = torch.Tensor()
        now = datetime.datetime.now().strftime('%Y-%m-%d-%H:%M:%S')

        if args.load == '.':
            if args.save == '.': args.save = now
            self.dir = './experiment/' + args.save
        else:
            self.dir = './experiment/' + args.load
            if not os.path.exists(self.dir):
                args.load = '.'
            else:
                self.log = torch.load(self.dir + '/psnr_log.pt')
                print('Continue from epoch {}...'.format(len(self.log)))

        if args.reset:
            os.system('rm -rf ' + self.dir)
            args.load = '.'

        def _make_dir(path):
            if not os.path.exists(path): os.makedirs(path)

        _make_dir(self.dir)
        _make_dir(self.dir + '/model')
        _make_dir(self.dir + '/results')

        open_type = 'a' if os.path.exists(self.dir + '/log.txt') else 'w'
        self.log_file = open(self.dir + '/log.txt', open_type)
        with open(self.dir + '/config.txt', open_type) as f:
            f.write(now + '\n\n')
            for arg in vars(args):
                f.write('{}: {}\n'.format(arg, getattr(args, arg)))
            f.write('\n')

    def save(self, trainer, epoch, is_best=False):
        trainer.model.save(self.dir, epoch, is_best=is_best)
        trainer.loss.save(self.dir)
        trainer.loss.plot_loss(self.dir, epoch)

        self.plot_psnr(epoch)
        torch.save(self.log, os.path.join(self.dir, 'psnr_log.pt'))
        torch.save(
            trainer.optimizer.state_dict(),
            os.path.join(self.dir, 'optimizer.pt')
        )

    def add_log(self, log):
        self.log = torch.cat([self.log, log])

    def write_log(self, log, refresh=False):
        print(log)
        self.log_file.write(log + '\n')
        if refresh:
            self.log_file.close()
            self.log_file = open(self.dir + '/log.txt', 'a')

    def done(self):
        self.log_file.close()

    def plot_psnr(self, epoch):
        axis = np.linspace(1, epoch, epoch)
        label = 'SR on {}'.format(self.args.data_test)
        fig = plt.figure()
        plt.title(label)
        for idx_scale, scale in enumerate(self.args.scale):
            plt.plot(
                axis,
                self.log[:, idx_scale].numpy(),
                label='Scale {}'.format(scale)
            )
        plt.legend()
        plt.xlabel('Epochs')
        plt.ylabel('PSNR')
        plt.grid(True)
        plt.savefig('{}/test_{}.pdf'.format(self.dir, self.args.data_test))
        plt.close(fig)

    def save_results(self, filename, save_list, scale):
        filename = '{}/results/{}_x{}_'.format(self.dir, filename, scale)
        postfix = ('SR', 'LR', 'HR')
        for v, p in zip(save_list, postfix):
            normalized = v[0].data.mul(255 / self.args.rgb_range)
            ndarr = normalized.byte().permute(1, 2, 0).cpu().numpy()
            misc.imsave('{}{}.png'.format(filename, p), ndarr)

def quantize(img, rgb_range):
    pixel_range = 255 / rgb_range
    return img.mul(pixel_range).clamp(0, 255).round().div(pixel_range)

def calc_psnr(sr, hr, scale, rgb_range, benchmark=False):
    #print(sr.size())
    #print(hr.size())
    diff = (sr - hr).data.div(rgb_range)
    if benchmark:
        shave = scale
        if diff.size(1) > 1:
            convert = diff.new(1, 3, 1, 1)
            convert[0, 0, 0, 0] = 65.738
            convert[0, 1, 0, 0] = 129.057
            convert[0, 2, 0, 0] = 25.064
            diff.mul_(convert).div_(256)
            diff = diff.sum(dim=1, keepdim=True)
    else:
        shave = scale + 6
    #shave = int(shave)
    import math
    shave = math.ceil(shave)
    valid = diff[:, :, shave:-shave, shave:-shave]
    mse = valid.pow(2).mean()

    return -10 * math.log10(mse)

    
def calc_ssim(img1, img2, scale=2, benchmark=False):
    '''calculate SSIM
    the same outputs as MATLAB's
    img1, img2: [0, 255]
    '''
    if benchmark:
        border = math.ceil(scale)
    else:
        border = math.ceil(scale)+6
        
    img1 = img1.data.squeeze().float().clamp(0,255).round().cpu().numpy()
    img1 = np.transpose(img1,(1,2,0))
    img2 = img2.data.squeeze().cpu().numpy()
    img2 = np.transpose(img2,(1,2,0))
    
    img1_y = np.dot(img1,[65.738,129.057,25.064])/255.0+16.0
    img2_y = np.dot(img2,[65.738,129.057,25.064])/255.0+16.0
    if not img1.shape == img2.shape:
        raise ValueError('Input images must have the same dimensions.')
    h, w = img1.shape[:2]
    img1_y = img1_y[border:h-border, border:w-border]
    img2_y = img2_y[border:h-border, border:w-border]

    if img1_y.ndim == 2:
        return ssim(img1_y, img2_y)
    elif img1.ndim == 3:
        if img1.shape[2] == 3:
            ssims = []
            for i in range(3):
                ssims.append(ssim(img1, img2))
            return np.array(ssims).mean()
        elif img1.shape[2] == 1:
            return ssim(np.squeeze(img1), np.squeeze(img2))
    else:
        raise ValueError('Wrong input image dimensions.')


def ssim(img1, img2):
    C1 = (0.01 * 255)**2
    C2 = (0.03 * 255)**2

    img1 = img1.astype(np.float64)
    img2 = img2.astype(np.float64)
    kernel = cv2.getGaussianKernel(11, 1.5)
    window = np.outer(kernel, kernel.transpose())

    mu1 = cv2.filter2D(img1, -1, window)[5:-5, 5:-5]  # valid
    mu2 = cv2.filter2D(img2, -1, window)[5:-5, 5:-5]
    mu1_sq = mu1**2
    mu2_sq = mu2**2
    mu1_mu2 = mu1 * mu2
    sigma1_sq = cv2.filter2D(img1**2, -1, window)[5:-5, 5:-5] - mu1_sq
    sigma2_sq = cv2.filter2D(img2**2, -1, window)[5:-5, 5:-5] - mu2_sq
    sigma12 = cv2.filter2D(img1 * img2, -1, window)[5:-5, 5:-5] - mu1_mu2

    ssim_map = ((2 * mu1_mu2 + C1) * (2 * sigma12 + C2)) / ((mu1_sq + mu2_sq + C1) *
                                                            (sigma1_sq + sigma2_sq + C2))
    return ssim_map.mean()
    
    
def make_optimizer(args, my_model):
    trainable = filter(lambda x: x.requires_grad, my_model.parameters())

    if args.optimizer == 'SGD':
        optimizer_function = optim.SGD
        kwargs = {'momentum': args.momentum}
    elif args.optimizer == 'ADAM':
        optimizer_function = optim.Adam
        kwargs = {
            'betas': (args.beta1, args.beta2),
            'eps': args.epsilon
        }
    elif args.optimizer == 'RMSprop':
        optimizer_function = optim.RMSprop
        kwargs = {'eps': args.epsilon}

    kwargs['lr'] = args.lr
    kwargs['weight_decay'] = args.weight_decay

    return optimizer_function(trainable, **kwargs)

def make_scheduler(args, my_optimizer):
    if args.decay_type == 'step':
        scheduler = lrs.StepLR(
            my_optimizer,
            step_size=args.lr_decay,
            gamma=args.gamma
            #last_epoch = args.start_epoch
        )
    elif args.decay_type.find('step') >= 0:
        milestones = args.decay_type.split('_')
        milestones.pop(0)
        milestones = list(map(lambda x: int(x), milestones))
        scheduler = lrs.MultiStepLR(
            my_optimizer,
            milestones=milestones,
            gamma=args.gamma
            #last_epoch = args.start_epoch
        )

    scheduler.step(args.start_epoch-1)

    return scheduler