
import cv2
import numpy as np
import pandas as pd
import requests
import torch
import torch.nn as nn
import yaml
from PIL import Image
from torch.cuda import amp


class DetectMultiBackend(nn.Module):
    # SIRD_YOLO MultiBackend class for python inference on various backends
    def __init__(self, weights='SIRD_YOLO.pt', device=None, dnn=False, data=None):
        from models.experimental import attempt_download, attempt_load  # scoped to avoid circular import

        super().__init__()
        w = str(weights[0] if isinstance(weights, list) else weights)
        pt, jit, onnx, xml, engine, coreml, saved_model, pb, tflite, edgetpu, tfjs = self.model_type(w)  # get backend
        stride, names = 64, [f'class{i}' for i in range(1000)]  # assign defaults
        w = attempt_download(w)  # download if not local
        if data:  # data.yaml path (optional)
            with open(data, errors='ignore') as f:
                names = yaml.safe_load(f)['names']  # class names

        if pt:  # PyTorch
            model = attempt_load(weights if isinstance(weights, list) else w, map_location=device)
            stride = max(int(model.stride.max()), 32)  # model stride
            names = model.module.names if hasattr(model, 'module') else model.names  # get class names
            self.model = model  # explicitly assign for to(), cpu(), cuda(), half()
        elif jit:  # TorchScript
            LOGGER.info(f'Loading {w} for TorchScript inference...')
            extra_files = {'config.txt': ''}  # model metadata
            model = torch.jit.load(w, _extra_files=extra_files)
            if extra_files['config.txt']:
                d = json.loads(extra_files['config.txt'])  # extra_files dict
                stride, names = int(d['stride']), d['names']
        elif dnn:  # ONNX OpenCV DNN
            LOGGER.info(f'Loading {w} for ONNX OpenCV DNN inference...')
            check_requirements(('opencv-python>=4.5.4',))
            net = cv2.dnn.readNetFromONNX(w)
        elif onnx:  # ONNX Runtime
            LOGGER.info(f'Loading {w} for ONNX Runtime inference...')
            cuda = torch.cuda.is_available()
            check_requirements(('onnx', 'onnxruntime-gpu' if cuda else 'onnxruntime'))
            import onnxruntime
            providers = ['CUDAExecutionProvider', 'CPUExecutionProvider'] if cuda else ['CPUExecutionProvider']
            session = onnxruntime.InferenceSession(w, providers=providers)
        elif xml:  # OpenVINO
            LOGGER.info(f'Loading {w} for OpenVINO inference...')
            check_requirements(('openvino-dev',))  # requires openvino-dev: https://pypi.org/project/openvino-dev/
            import openvino.inference_engine as ie
            core = ie.IECore()
            if not Path(w).is_file():  # if not *.xml
                w = next(Path(w).glob('*.xml'))  # get *.xml file from *_openvino_model dir
            network = core.read_network(model=w, weights=Path(w).with_suffix('.bin'))  # *.xml, *.bin paths
            executable_network = core.load_network(network, device_name='CPU', num_requests=1)
        elif engine:  # TensorRT
            LOGGER.info(f'Loading {w} for TensorRT inference...')
            import tensorrt as trt  # https://developer.nvidia.com/nvidia-tensorrt-download
            check_version(trt.__version__, '7.0.0', hard=True)  # require tensorrt>=7.0.0
            Binding = namedtuple('Binding', ('name', 'dtype', 'shape', 'data', 'ptr'))
            logger = trt.Logger(trt.Logger.INFO)
            with open(w, 'rb') as f, trt.Runtime(logger) as runtime:
                model = runtime.deserialize_cuda_engine(f.read())
            bindings = OrderedDict()
            for index in range(model.num_bindings):
                name = model.get_binding_name(index)
                dtype = trt.nptype(model.get_binding_dtype(index))
                shape = tuple(model.get_binding_shape(index))
                data = torch.from_numpy(np.empty(shape, dtype=np.dtype(dtype))).to(device)
                bindings[name] = Binding(name, dtype, shape, data, int(data.data_ptr()))
            binding_addrs = OrderedDict((n, d.ptr) for n, d in bindings.items())
            context = model.create_execution_context()
            batch_size = bindings['images'].shape[0]
        elif coreml:  # CoreML
            LOGGER.info(f'Loading {w} for CoreML inference...')
            import coremltools as ct
            model = ct.models.MLModel(w)
        else:  # TensorFlow (SavedModel, GraphDef, Lite, Edge TPU)
            if saved_model:  # SavedModel
                LOGGER.info(f'Loading {w} for TensorFlow SavedModel inference...')
                import tensorflow as tf
                keras = False  # assume TF1 saved_model
                model = tf.keras.models.load_model(w) if keras else tf.saved_model.load(w)
            elif pb:  # GraphDef https://www.tensorflow.org/guide/migrate#a_graphpb_or_graphpbtxt
                LOGGER.info(f'Loading {w} for TensorFlow GraphDef inference...')
                import tensorflow as tf

                def wrap_frozen_graph(gd, inputs, outputs):
                    x = tf.compat.v1.wrap_function(lambda: tf.compat.v1.import_graph_def(gd, name=""), [])  # wrapped
                    ge = x.graph.as_graph_element
                    return x.prune(tf.nest.map_structure(ge, inputs), tf.nest.map_structure(ge, outputs))

                gd = tf.Graph().as_graph_def()  # graph_def
                gd.ParseFromString(open(w, 'rb').read())
                frozen_func = wrap_frozen_graph(gd, inputs="x:0", outputs="Identity:0")
            elif tflite or edgetpu:  # https://www.tensorflow.org/lite/guide/python#install_tensorflow_lite_for_python
                try:  # https://coral.ai/docs/edgetpu/tflite-python/#update-existing-tf-lite-code-for-the-edge-tpu
                    from tflite_runtime.interpreter import Interpreter, load_delegate
                except ImportError:
                    import tensorflow as tf
                    Interpreter, load_delegate = tf.lite.Interpreter, tf.lite.experimental.load_delegate,
                if edgetpu:  # Edge TPU https://coral.ai/software/#edgetpu-runtime
                    LOGGER.info(f'Loading {w} for TensorFlow Lite Edge TPU inference...')
                    delegate = {'Linux': 'libedgetpu.so.1',
                                'Darwin': 'libedgetpu.1.dylib',
                                'Windows': 'edgetpu.dll'}[platform.system()]
                    interpreter = Interpreter(model_path=w, experimental_delegates=[load_delegate(delegate)])
                else:  # Lite
                    LOGGER.info(f'Loading {w} for TensorFlow Lite inference...')
                    interpreter = Interpreter(model_path=w)  # load TFLite model
                interpreter.allocate_tensors()  # allocate
                input_details = interpreter.get_input_details()  # inputs
                output_details = interpreter.get_output_details()  # outputs
            elif tfjs:
                raise Exception('ERROR: SIRD_YOLO TF.js inference is not supported')
        self.__dict__.update(locals())  # assign all variables to self

    def forward(self, im, augment=False, visualize=False, val=False):
        # SIRD_YOLO MultiBackend inference
        b, ch, h, w = im.shape  # batch, channel, height, width
        if self.pt or self.jit:  # PyTorch
            y = self.model(im) if self.jit else self.model(im, augment=augment, visualize=visualize)
            return y if val else y[0]
        elif self.dnn:  # ONNX OpenCV DNN
            im = im.cpu().numpy()  # torch to numpy
            self.net.setInput(im)
            y = self.net.forward()
        elif self.onnx:  # ONNX Runtime
            im = im.cpu().numpy()  # torch to numpy
            y = self.session.run([self.session.get_outputs()[0].name], {self.session.get_inputs()[0].name: im})[0]
        elif self.xml:  # OpenVINO
            im = im.cpu().numpy()  # FP32
            desc = self.ie.TensorDesc(precision='FP32', dims=im.shape, layout='NCHW')  # Tensor Description
            request = self.executable_network.requests[0]  # inference request
            request.set_blob(blob_name='images', blob=self.ie.Blob(desc, im))  # name=next(iter(request.input_blobs))
            request.infer()
            y = request.output_blobs['output'].buffer  # name=next(iter(request.output_blobs))
        elif self.engine:  # TensorRT
            assert im.shape == self.bindings['images'].shape, (im.shape, self.bindings['images'].shape)
            self.binding_addrs['images'] = int(im.data_ptr())
            self.context.execute_v2(list(self.binding_addrs.values()))
            y = self.bindings['output'].data
        elif self.coreml:  # CoreML
            im = im.permute(0, 2, 3, 1).cpu().numpy()  # torch BCHW to numpy BHWC shape(1,320,192,3)
            im = Image.fromarray((im[0] * 255).astype('uint8'))
            # im = im.resize((192, 320), Image.ANTIALIAS)
            y = self.model.predict({'image': im})  # coordinates are xywh normalized
            if 'confidence' in y:
                box = xywh2xyxy(y['coordinates'] * [[w, h, w, h]])  # xyxy pixels
                conf, cls = y['confidence'].max(1), y['confidence'].argmax(1).astype(np.float)
                y = np.concatenate((box, conf.reshape(-1, 1), cls.reshape(-1, 1)), 1)
            else:
                k = 'var_' + str(sorted(int(k.replace('var_', '')) for k in y)[-1])  # output key
                y = y[k]  # output
        else:  # TensorFlow (SavedModel, GraphDef, Lite, Edge TPU)
            im = im.permute(0, 2, 3, 1).cpu().numpy()  # torch BCHW to numpy BHWC shape(1,320,192,3)
            if self.saved_model:  # SavedModel
                y = (self.model(im, training=False) if self.keras else self.model(im)[0]).numpy()
            elif self.pb:  # GraphDef
                y = self.frozen_func(x=self.tf.constant(im)).numpy()
            else:  # Lite or Edge TPU
                input, output = self.input_details[0], self.output_details[0]
                int8 = input['dtype'] == np.uint8  # is TFLite quantized uint8 model
                if int8:
                    scale, zero_point = input['quantization']
                    im = (im / scale + zero_point).astype(np.uint8)  # de-scale
                self.interpreter.set_tensor(input['index'], im)
                self.interpreter.invoke()
                y = self.interpreter.get_tensor(output['index'])
                if int8:
                    scale, zero_point = output['quantization']
                    y = (y.astype(np.float32) - zero_point) * scale  # re-scale
            y[..., :4] *= [w, h, w, h]  # xywh normalized to pixels

        y = torch.tensor(y) if isinstance(y, np.ndarray) else y
        return (y, []) if val else y

    def warmup(self, imgsz=(1, 3, 640, 640), half=False):
        # Warmup model by running inference once
        if self.pt or self.jit or self.onnx or self.engine:  # warmup types
            if isinstance(self.device, torch.device) and self.device.type != 'cpu':  # only warmup GPU models
                im = torch.zeros(*imgsz).to(self.device).type(torch.half if half else torch.float)  # input image
                self.forward(im)  # warmup

    @staticmethod
    def model_type(p='path/to/model.pt'):
        # Return model type from model path, i.e. path='path/to/model.onnx' -> type=onnx
        from tools.export import export_formats
        suffixes = list(export_formats().Suffix) + ['.xml']  # export suffixes
        check_suffix(p, suffixes)  # checks
        p = Path(p).name  # eliminate trailing separators
        pt, jit, onnx, xml, engine, coreml, saved_model, pb, tflite, edgetpu, tfjs, xml2 = (s in p for s in suffixes)
        xml |= xml2  # *_openvino_model or *.xml
        tflite &= not edgetpu  # *.tflite
        return pt, jit, onnx, xml, engine, coreml, saved_model, pb, tflite, edgetpu, tfjs
