import torch
from torchvision import transforms as T
from torchvision.transforms import functional as F
from PIL import Image
from PIL.Image import NEAREST, BILINEAR, BICUBIC

import numpy as np

import unittest


class Tester(unittest.TestCase):
    def _create_data(self, height=3, width=3, channels=3):
        tensor = torch.randint(0, 255, (channels, height, width), dtype=torch.uint8)
        pil_img = Image.fromarray(tensor.permute(1, 2, 0).contiguous().numpy())
        return tensor, pil_img

    def compareTensorToPIL(self, tensor, pil_image):
        pil_tensor = torch.as_tensor(np.array(pil_image).transpose((2, 0, 1)))
        self.assertTrue(tensor.equal(pil_tensor))

    def _test_functional_geom_op(self, func, fn_kwargs):
        if fn_kwargs is None:
            fn_kwargs = {}
        tensor, pil_img = self._create_data(height=10, width=10)
        transformed_tensor = getattr(F, func)(tensor, **fn_kwargs)
        transformed_pil_img = getattr(F, func)(pil_img, **fn_kwargs)
        self.compareTensorToPIL(transformed_tensor, transformed_pil_img)

    def _test_class_geom_op(self, method, meth_kwargs=None):
        if meth_kwargs is None:
            meth_kwargs = {}

        tensor, pil_img = self._create_data(height=10, width=10)
        # test for class interface
        f = getattr(T, method)(**meth_kwargs)
        scripted_fn = torch.jit.script(f)

        # set seed to reproduce the same transformation for tensor and PIL image
        torch.manual_seed(12)
        transformed_tensor = f(tensor)
        torch.manual_seed(12)
        transformed_pil_img = f(pil_img)
        self.compareTensorToPIL(transformed_tensor, transformed_pil_img)

        torch.manual_seed(12)
        transformed_tensor_script = scripted_fn(tensor)
        self.assertTrue(transformed_tensor.equal(transformed_tensor_script))

    def _test_geom_op(self, func, method, fn_kwargs=None, meth_kwargs=None):
        self._test_functional_geom_op(func, fn_kwargs)
        self._test_class_geom_op(method, meth_kwargs)

    def test_random_horizontal_flip(self):
        self._test_geom_op('hflip', 'RandomHorizontalFlip')

    def test_random_vertical_flip(self):
        self._test_geom_op('vflip', 'RandomVerticalFlip')

    def test_adjustments(self):
        fns = ['adjust_brightness', 'adjust_contrast', 'adjust_saturation']
        for _ in range(20):
            factor = 3 * torch.rand(1).item()
            tensor, _ = self._create_data()
            pil_img = T.ToPILImage()(tensor)

            for func in fns:
                adjusted_tensor = getattr(F, func)(tensor, factor)
                adjusted_pil_img = getattr(F, func)(pil_img, factor)

                adjusted_pil_tensor = T.ToTensor()(adjusted_pil_img)
                scripted_fn = torch.jit.script(getattr(F, func))
                adjusted_tensor_script = scripted_fn(tensor, factor)

                if not tensor.dtype.is_floating_point:
                    adjusted_tensor = adjusted_tensor.to(torch.float) / 255
                    adjusted_tensor_script = adjusted_tensor_script.to(torch.float) / 255

                # F uses uint8 and F_t uses float, so there is a small
                # difference in values caused by (at most 5) truncations.
                max_diff = (adjusted_tensor - adjusted_pil_tensor).abs().max()
                max_diff_scripted = (adjusted_tensor - adjusted_tensor_script).abs().max()
                self.assertLess(max_diff, 5 / 255 + 1e-5)
                self.assertLess(max_diff_scripted, 5 / 255 + 1e-5)

    def test_pad(self):

        # Test functional.pad (PIL and Tensor) with padding as single int
        self._test_functional_geom_op(
            "pad", fn_kwargs={"padding": 2, "fill": 0, "padding_mode": "constant"}
        )
        # Test functional.pad and transforms.Pad with padding as [int, ]
        fn_kwargs = meth_kwargs = {"padding": [2, ], "fill": 0, "padding_mode": "constant"}
        self._test_geom_op(
            "pad", "Pad", fn_kwargs=fn_kwargs, meth_kwargs=meth_kwargs
        )
        # Test functional.pad and transforms.Pad with padding as list
        fn_kwargs = meth_kwargs = {"padding": [4, 4], "fill": 0, "padding_mode": "constant"}
        self._test_geom_op(
            "pad", "Pad", fn_kwargs=fn_kwargs, meth_kwargs=meth_kwargs
        )
        # Test functional.pad and transforms.Pad with padding as tuple
        fn_kwargs = meth_kwargs = {"padding": (2, 2, 2, 2), "fill": 127, "padding_mode": "constant"}
        self._test_geom_op(
            "pad", "Pad", fn_kwargs=fn_kwargs, meth_kwargs=meth_kwargs
        )

    def test_crop(self):
        fn_kwargs = {"top": 2, "left": 3, "height": 4, "width": 5}
        # Test transforms.RandomCrop with size and padding as tuple
        meth_kwargs = {"size": (4, 5), "padding": (4, 4), "pad_if_needed": True, }
        self._test_geom_op(
            'crop', 'RandomCrop', fn_kwargs=fn_kwargs, meth_kwargs=meth_kwargs
        )

        sizes = [5, [5, ], [6, 6]]
        padding_configs = [
            {"padding_mode": "constant", "fill": 0},
            {"padding_mode": "constant", "fill": 10},
            {"padding_mode": "constant", "fill": 20},
            {"padding_mode": "edge"},
            {"padding_mode": "reflect"},
        ]

        for size in sizes:
            for padding_config in padding_configs:
                config = dict(padding_config)
                config["size"] = size
                self._test_class_geom_op("RandomCrop", config)

    def test_center_crop(self):
        fn_kwargs = {"output_size": (4, 5)}
        meth_kwargs = {"size": (4, 5), }
        self._test_geom_op(
            "center_crop", "CenterCrop", fn_kwargs=fn_kwargs, meth_kwargs=meth_kwargs
        )
        fn_kwargs = {"output_size": (5,)}
        meth_kwargs = {"size": (5, )}
        self._test_geom_op(
            "center_crop", "CenterCrop", fn_kwargs=fn_kwargs, meth_kwargs=meth_kwargs
        )
        tensor = torch.randint(0, 255, (3, 10, 10), dtype=torch.uint8)
        # Test torchscript of transforms.CenterCrop with size as int
        f = T.CenterCrop(size=5)
        scripted_fn = torch.jit.script(f)
        scripted_fn(tensor)

        # Test torchscript of transforms.CenterCrop with size as [int, ]
        f = T.CenterCrop(size=[5, ])
        scripted_fn = torch.jit.script(f)
        scripted_fn(tensor)

        # Test torchscript of transforms.CenterCrop with size as tuple
        f = T.CenterCrop(size=(6, 6))
        scripted_fn = torch.jit.script(f)
        scripted_fn(tensor)

    def _test_geom_op_list_output(self, func, method, out_length, fn_kwargs=None, meth_kwargs=None):
        if fn_kwargs is None:
            fn_kwargs = {}
        if meth_kwargs is None:
            meth_kwargs = {}
        tensor, pil_img = self._create_data(height=20, width=20)
        transformed_t_list = getattr(F, func)(tensor, **fn_kwargs)
        transformed_p_list = getattr(F, func)(pil_img, **fn_kwargs)
        self.assertEqual(len(transformed_t_list), len(transformed_p_list))
        self.assertEqual(len(transformed_t_list), out_length)
        for transformed_tensor, transformed_pil_img in zip(transformed_t_list, transformed_p_list):
            self.compareTensorToPIL(transformed_tensor, transformed_pil_img)

        scripted_fn = torch.jit.script(getattr(F, func))
        transformed_t_list_script = scripted_fn(tensor.detach().clone(), **fn_kwargs)
        self.assertEqual(len(transformed_t_list), len(transformed_t_list_script))
        self.assertEqual(len(transformed_t_list_script), out_length)
        for transformed_tensor, transformed_tensor_script in zip(transformed_t_list, transformed_t_list_script):
            self.assertTrue(transformed_tensor.equal(transformed_tensor_script),
                            msg="{} vs {}".format(transformed_tensor, transformed_tensor_script))

        # test for class interface
        f = getattr(T, method)(**meth_kwargs)
        scripted_fn = torch.jit.script(f)
        output = scripted_fn(tensor)
        self.assertEqual(len(output), len(transformed_t_list_script))

    def test_five_crop(self):
        fn_kwargs = meth_kwargs = {"size": (5,)}
        self._test_geom_op_list_output(
            "five_crop", "FiveCrop", out_length=5, fn_kwargs=fn_kwargs, meth_kwargs=meth_kwargs
        )
        fn_kwargs = meth_kwargs = {"size": [5, ]}
        self._test_geom_op_list_output(
            "five_crop", "FiveCrop", out_length=5, fn_kwargs=fn_kwargs, meth_kwargs=meth_kwargs
        )
        fn_kwargs = meth_kwargs = {"size": (4, 5)}
        self._test_geom_op_list_output(
            "five_crop", "FiveCrop", out_length=5, fn_kwargs=fn_kwargs, meth_kwargs=meth_kwargs
        )
        fn_kwargs = meth_kwargs = {"size": [4, 5]}
        self._test_geom_op_list_output(
            "five_crop", "FiveCrop", out_length=5, fn_kwargs=fn_kwargs, meth_kwargs=meth_kwargs
        )

    def test_ten_crop(self):
        fn_kwargs = meth_kwargs = {"size": (5,)}
        self._test_geom_op_list_output(
            "ten_crop", "TenCrop", out_length=10, fn_kwargs=fn_kwargs, meth_kwargs=meth_kwargs
        )
        fn_kwargs = meth_kwargs = {"size": [5, ]}
        self._test_geom_op_list_output(
            "ten_crop", "TenCrop", out_length=10, fn_kwargs=fn_kwargs, meth_kwargs=meth_kwargs
        )
        fn_kwargs = meth_kwargs = {"size": (4, 5)}
        self._test_geom_op_list_output(
            "ten_crop", "TenCrop", out_length=10, fn_kwargs=fn_kwargs, meth_kwargs=meth_kwargs
        )
        fn_kwargs = meth_kwargs = {"size": [4, 5]}
        self._test_geom_op_list_output(
            "ten_crop", "TenCrop", out_length=10, fn_kwargs=fn_kwargs, meth_kwargs=meth_kwargs
        )

    def test_resize(self):
        tensor, _ = self._create_data(height=34, width=36)
        script_fn = torch.jit.script(F.resize)

        for dt in [None, torch.float32, torch.float64]:
            if dt is not None:
                # This is a trivial cast to float of uint8 data to test all cases
                tensor = tensor.to(dt)
            for size in [32, [32, ], [32, 32], (32, 32), ]:
                for interpolation in [BILINEAR, BICUBIC, NEAREST]:

                    resized_tensor = F.resize(tensor, size=size, interpolation=interpolation)

                    if isinstance(size, int):
                        script_size = [size, ]
                    else:
                        script_size = size

                    s_resized_tensor = script_fn(tensor, size=script_size, interpolation=interpolation)
                    self.assertTrue(s_resized_tensor.equal(resized_tensor))

                    transform = T.Resize(size=script_size, interpolation=interpolation)
                    resized_tensor = transform(tensor)
                    script_transform = torch.jit.script(transform)
                    s_resized_tensor = script_transform(tensor)
                    self.assertTrue(s_resized_tensor.equal(resized_tensor))

    def test_resized_crop(self):
        tensor = torch.randint(0, 255, size=(3, 44, 56), dtype=torch.uint8)

        scale = (0.7, 1.2)
        ratio = (0.75, 1.333)

        for size in [(32, ), [32, ], [32, 32], (32, 32)]:
            for interpolation in [NEAREST, BILINEAR, BICUBIC]:
                transform = T.RandomResizedCrop(
                    size=size, scale=scale, ratio=ratio, interpolation=interpolation
                )
                s_transform = torch.jit.script(transform)

                torch.manual_seed(12)
                out1 = transform(tensor)
                torch.manual_seed(12)
                out2 = s_transform(tensor)
                self.assertTrue(out1.equal(out2))


if __name__ == '__main__':
    unittest.main()
