import numpy as np
import random
import torch
from basicsr.data.degradations import (
    random_add_gaussian_noise_pt,
    random_add_poisson_noise_pt,
)
from basicsr.data.transforms import paired_random_crop
from basicsr.models.sr_model import SRModel
from basicsr.utils import DiffJPEG, USMSharp
from basicsr.utils.img_process_util import filter2D
from basicsr.utils.registry import MODEL_REGISTRY
from torch.nn import functional as F


@MODEL_REGISTRY.register()
class RealESRNetModel(SRModel):
    """RealESRNet Model for Real-ESRGAN: Training Real-World Blind Super-Resolution with Pure Synthetic Data.

    It is trained without GAN losses.
    It mainly performs:
    1. randomly synthesize LQ images in GPU tensors
    2. optimize the networks with GAN training.
    """

    def __init__(self, opt):
        super(RealESRNetModel, self).__init__(opt)
        self.jpeger = DiffJPEG(
            differentiable=False
        ).cuda()  # simulate JPEG compression artifacts
        self.usm_sharpener = USMSharp().cuda()  # do usm sharpening
        self.queue_size = opt.get("queue_size", 180)

    @torch.no_grad()
    def _dequeue_and_enqueue(self):
        """It is the training pair pool for increasing the diversity in a batch.

        Batch processing limits the diversity of synthetic degradations in a batch. For example, samples in a
        batch could not have different resize scaling factors. Therefore, we employ this training pair pool
        to increase the degradation diversity in a batch.
        """
        # initialize
        b, c, h, w = self.lq.size()
        if not hasattr(self, "queue_lr"):
            assert (
                self.queue_size % b == 0
            ), f"queue size {self.queue_size} should be divisible by batch size {b}"
            self.queue_lr = torch.zeros(self.queue_size, c, h, w).cuda()
            _, c, h, w = self.gt.size()
            self.queue_gt = torch.zeros(self.queue_size, c, h, w).cuda()
            self.queue_ptr = 0
        if self.queue_ptr == self.queue_size:  # the pool is full
            # do dequeue and enqueue
            # shuffle
            idx = torch.randperm(self.queue_size)
            self.queue_lr = self.queue_lr[idx]
            self.queue_gt = self.queue_gt[idx]
            # get first b samples
            lq_dequeue = self.queue_lr[0:b, :, :, :].clone()
            gt_dequeue = self.queue_gt[0:b, :, :, :].clone()
            # update the queue
            self.queue_lr[0:b, :, :, :] = self.lq.clone()
            self.queue_gt[0:b, :, :, :] = self.gt.clone()

            self.lq = lq_dequeue
            self.gt = gt_dequeue
        else:
            # only do enqueue
            self.queue_lr[
                self.queue_ptr : self.queue_ptr + b, :, :, :
            ] = self.lq.clone()
            self.queue_gt[
                self.queue_ptr : self.queue_ptr + b, :, :, :
            ] = self.gt.clone()
            self.queue_ptr = self.queue_ptr + b

    @torch.no_grad()
    def feed_data(self, data):
        """Accept data from dataloader, and then add two-order degradations to obtain LQ images."""
        if self.is_train and self.opt.get("high_order_degradation", True):
            # training data synthesis
            self.gt = data["gt"].to(self.device)
            # USM sharpen the GT images
            if self.opt["gt_usm"] is True:
                self.gt = self.usm_sharpener(self.gt)

            self.kernel1 = data["kernel1"].to(self.device)
            self.kernel2 = data["kernel2"].to(self.device)
            self.sinc_kernel = data["sinc_kernel"].to(self.device)

            ori_h, ori_w = self.gt.size()[2:4]

            # ----------------------- The first degradation process ----------------------- #
            # blur
            out = filter2D(self.gt, self.kernel1)
            # random resize
            updown_type = random.choices(
                ["up", "down", "keep"], self.opt["resize_prob"]
            )[0]
            if updown_type == "up":
                scale = np.random.uniform(1, self.opt["resize_range"][1])
            elif updown_type == "down":
                scale = np.random.uniform(self.opt["resize_range"][0], 1)
            else:
                scale = 1
            mode = random.choice(["area", "bilinear", "bicubic"])
            out = F.interpolate(out, scale_factor=scale, mode=mode)
            # add noise
            gray_noise_prob = self.opt["gray_noise_prob"]
            if np.random.uniform() < self.opt["gaussian_noise_prob"]:
                out = random_add_gaussian_noise_pt(
                    out,
                    sigma_range=self.opt["noise_range"],
                    clip=True,
                    rounds=False,
                    gray_prob=gray_noise_prob,
                )
            else:
                out = random_add_poisson_noise_pt(
                    out,
                    scale_range=self.opt["poisson_scale_range"],
                    gray_prob=gray_noise_prob,
                    clip=True,
                    rounds=False,
                )
            # JPEG compression
            jpeg_p = out.new_zeros(out.size(0)).uniform_(*self.opt["jpeg_range"])
            out = torch.clamp(
                out, 0, 1
            )  # clamp to [0, 1], otherwise JPEGer will result in unpleasant artifacts
            out = self.jpeger(out, quality=jpeg_p)

            # ----------------------- The second degradation process ----------------------- #
            # blur
            if np.random.uniform() < self.opt["second_blur_prob"]:
                out = filter2D(out, self.kernel2)
            # random resize
            updown_type = random.choices(
                ["up", "down", "keep"], self.opt["resize_prob2"]
            )[0]
            if updown_type == "up":
                scale = np.random.uniform(1, self.opt["resize_range2"][1])
            elif updown_type == "down":
                scale = np.random.uniform(self.opt["resize_range2"][0], 1)
            else:
                scale = 1
            mode = random.choice(["area", "bilinear", "bicubic"])
            out = F.interpolate(
                out,
                size=(
                    int(ori_h / self.opt["scale"] * scale),
                    int(ori_w / self.opt["scale"] * scale),
                ),
                mode=mode,
            )
            # add noise
            gray_noise_prob = self.opt["gray_noise_prob2"]
            if np.random.uniform() < self.opt["gaussian_noise_prob2"]:
                out = random_add_gaussian_noise_pt(
                    out,
                    sigma_range=self.opt["noise_range2"],
                    clip=True,
                    rounds=False,
                    gray_prob=gray_noise_prob,
                )
            else:
                out = random_add_poisson_noise_pt(
                    out,
                    scale_range=self.opt["poisson_scale_range2"],
                    gray_prob=gray_noise_prob,
                    clip=True,
                    rounds=False,
                )

            # JPEG compression + the final sinc filter
            # We also need to resize images to desired sizes. We group [resize back + sinc filter] together
            # as one operation.
            # We consider two orders:
            #   1. [resize back + sinc filter] + JPEG compression
            #   2. JPEG compression + [resize back + sinc filter]
            # Empirically, we find other combinations (sinc + JPEG + Resize) will introduce twisted lines.
            if np.random.uniform() < 0.5:
                # resize back + the final sinc filter
                mode = random.choice(["area", "bilinear", "bicubic"])
                out = F.interpolate(
                    out,
                    size=(ori_h // self.opt["scale"], ori_w // self.opt["scale"]),
                    mode=mode,
                )
                out = filter2D(out, self.sinc_kernel)
                # JPEG compression
                jpeg_p = out.new_zeros(out.size(0)).uniform_(*self.opt["jpeg_range2"])
                out = torch.clamp(out, 0, 1)
                out = self.jpeger(out, quality=jpeg_p)
            else:
                # JPEG compression
                jpeg_p = out.new_zeros(out.size(0)).uniform_(*self.opt["jpeg_range2"])
                out = torch.clamp(out, 0, 1)
                out = self.jpeger(out, quality=jpeg_p)
                # resize back + the final sinc filter
                mode = random.choice(["area", "bilinear", "bicubic"])
                out = F.interpolate(
                    out,
                    size=(ori_h // self.opt["scale"], ori_w // self.opt["scale"]),
                    mode=mode,
                )
                out = filter2D(out, self.sinc_kernel)

            # clamp and round
            self.lq = torch.clamp((out * 255.0).round(), 0, 255) / 255.0

            # random crop
            gt_size = self.opt["gt_size"]
            self.gt, self.lq = paired_random_crop(
                self.gt, self.lq, gt_size, self.opt["scale"]
            )

            # training pair pool
            self._dequeue_and_enqueue()
            self.lq = (
                self.lq.contiguous()
            )  # for the warning: grad and param do not obey the gradient layout contract
        else:
            # for paired training or validation
            self.lq = data["lq"].to(self.device)
            if "gt" in data:
                self.gt = data["gt"].to(self.device)
                self.gt_usm = self.usm_sharpener(self.gt)

    def nondist_validation(self, dataloader, current_iter, tb_logger, save_img):
        # do not use the synthetic process during validation
        self.is_train = False
        super(RealESRNetModel, self).nondist_validation(
            dataloader, current_iter, tb_logger, save_img
        )
        self.is_train = True