# Ultralytics YOLO 🚀, AGPL-3.0 license

import ast
import contextlib
import json
import platform
import zipfile
from collections import OrderedDict, namedtuple
from pathlib import Path

import cv2
import numpy as np
import torch
import torch.nn as nn
from PIL import Image

from ultralytics.utils import ARM64, LINUX, LOGGER, ROOT, yaml_load
from ultralytics.utils.checks import check_requirements, check_suffix, check_version, check_yaml
from ultralytics.utils.downloads import attempt_download_asset, is_url


def check_class_names(names):
    """
    Check class names.

    Map imagenet class codes to human-readable names if required. Convert lists to dicts.
    """
    if isinstance(names, list):  # names is a list
        names = dict(enumerate(names))  # convert to dict
    if isinstance(names, dict):
        # Convert 1) string keys to int, i.e. '0' to 0, and non-string values to strings, i.e. True to 'True'
        names = {int(k): str(v) for k, v in names.items()}
        n = len(names)
        if max(names.keys()) >= n:
            raise KeyError(f'{n}-class dataset requires class indices 0-{n - 1}, but you have invalid class indices '
                           f'{min(names.keys())}-{max(names.keys())} defined in your dataset YAML.')
        if isinstance(names[0], str) and names[0].startswith('n0'):  # imagenet class codes, i.e. 'n01440764'
            names_map = yaml_load(ROOT / 'cfg/datasets/ImageNet.yaml')['map']  # human-readable names
            names = {k: names_map[v] for k, v in names.items()}
    return names


class AutoBackend(nn.Module):
    """
    Handles dynamic backend selection for running inference using Ultralytics YOLO models.

    The AutoBackend class is designed to provide an abstraction layer for various inference engines. It supports a wide
    range of formats, each with specific naming conventions as outlined below:

        Supported Formats and Naming Conventions:
            | Format                | File Suffix      |
            |-----------------------|------------------|
            | PyTorch               | *.pt             |
            | TorchScript           | *.torchscript    |
            | ONNX Runtime          | *.onnx           |
            | ONNX OpenCV DNN       | *.onnx (dnn=True)|
            | OpenVINO              | *openvino_model/ |
            | CoreML                | *.mlpackage      |
            | TensorRT              | *.engine         |
            | TensorFlow SavedModel | *_saved_model    |
            | TensorFlow GraphDef   | *.pb             |
            | TensorFlow Lite       | *.tflite         |
            | TensorFlow Edge TPU   | *_edgetpu.tflite |
            | PaddlePaddle          | *_paddle_model   |
            | ncnn                  | *_ncnn_model     |

    This class offers dynamic backend switching capabilities based on the input model format, making it easier to deploy
    models across various platforms.
    """

    @torch.no_grad()
    def __init__(self,
                 weights='yolov8n.pt',
                 device=torch.device('cpu'),
                 dnn=False,
                 data=None,
                 fp16=False,
                 fuse=True,
                 verbose=True):
        """
        Initialize the AutoBackend for inference.

        Args:
            weights (str): Path to the model weights file. Defaults to 'yolov8n.pt'.
            device (torch.device): Device to run the model on. Defaults to CPU.
            dnn (bool): Use OpenCV DNN module for ONNX inference. Defaults to False.
            data (str | Path | optional): Path to the additional data.yaml file containing class names. Optional.
            fp16 (bool): Enable half-precision inference. Supported only on specific backends. Defaults to False.
            fuse (bool): Fuse Conv2D + BatchNorm layers for optimization. Defaults to True.
            verbose (bool): Enable verbose logging. Defaults to True.
        """
        super().__init__()
        w = str(weights[0] if isinstance(weights, list) else weights)
        nn_module = isinstance(weights, torch.nn.Module)
        pt, jit, onnx, xml, engine, coreml, saved_model, pb, tflite, edgetpu, tfjs, paddle, ncnn, triton = \
            self._model_type(w)
        fp16 &= pt or jit or onnx or xml or engine or nn_module or triton  # FP16
        nhwc = coreml or saved_model or pb or tflite or edgetpu  # BHWC formats (vs torch BCWH)
        stride = 32  # default stride
        model, metadata = None, None

        # Set device
        cuda = torch.cuda.is_available() and device.type != 'cpu'  # use CUDA
        if cuda and not any([nn_module, pt, jit, engine]):  # GPU dataloader formats
            device = torch.device('cpu')
            cuda = False

        # Download if not local
        if not (pt or triton or nn_module):
            w = attempt_download_asset(w)

        # Load model
        if nn_module:  # in-memory PyTorch model
            model = weights.to(device)
            model = model.fuse(verbose=verbose) if fuse else model
            if hasattr(model, 'kpt_shape'):
                kpt_shape = model.kpt_shape  # pose-only
            stride = max(int(model.stride.max()), 32)  # model stride
            names = model.module.names if hasattr(model, 'module') else model.names  # get class names
            model.half() if fp16 else model.float()
            self.model = model  # explicitly assign for to(), cpu(), cuda(), half()
            pt = True
        elif pt:  # PyTorch
            from ultralytics.nn.tasks import attempt_load_weights
            model = attempt_load_weights(weights if isinstance(weights, list) else w,
                                         device=device,
                                         inplace=True,
                                         fuse=fuse)
            if hasattr(model, 'kpt_shape'):
                kpt_shape = model.kpt_shape  # pose-only
            stride = max(int(model.stride.max()), 32)  # model stride
            names = model.module.names if hasattr(model, 'module') else model.names  # get class names
            model.half() if fp16 else model.float()
            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, map_location=device)
            model.half() if fp16 else model.float()
            if extra_files['config.txt']:  # load metadata dict
                metadata = json.loads(extra_files['config.txt'], object_hook=lambda x: dict(x.items()))
        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...')
            check_requirements(('onnx', 'onnxruntime-gpu' if cuda else 'onnxruntime'))
            import onnxruntime
            providers = ['CUDAExecutionProvider', 'CPUExecutionProvider'] if cuda else ['CPUExecutionProvider']
            session = onnxruntime.InferenceSession(w, providers=providers)
            output_names = [x.name for x in session.get_outputs()]
            metadata = session.get_modelmeta().custom_metadata_map  # metadata
        elif xml:  # OpenVINO
            LOGGER.info(f'Loading {w} for OpenVINO inference...')
            check_requirements('openvino>=2023.0')  # requires openvino-dev: https://pypi.org/project/openvino-dev/
            from openvino.runtime import Core, Layout, get_batch  # noqa
            core = Core()
            w = Path(w)
            if not w.is_file():  # if not *.xml
                w = next(w.glob('*.xml'))  # get *.xml file from *_openvino_model dir
            ov_model = core.read_model(model=str(w), weights=w.with_suffix('.bin'))
            if ov_model.get_parameters()[0].get_layout().empty:
                ov_model.get_parameters()[0].set_layout(Layout('NCHW'))
            batch_dim = get_batch(ov_model)
            if batch_dim.is_static:
                batch_size = batch_dim.get_length()
            ov_compiled_model = core.compile_model(ov_model, device_name='AUTO')  # AUTO selects best available device
            metadata = w.parent / 'metadata.yaml'
        elif engine:  # TensorRT
            LOGGER.info(f'Loading {w} for TensorRT inference...')
            try:
                import tensorrt as trt  # noqa https://developer.nvidia.com/nvidia-tensorrt-download
            except ImportError:
                if LINUX:
                    check_requirements('nvidia-tensorrt', cmds='-U --index-url https://pypi.ngc.nvidia.com')
                import tensorrt as trt  # noqa
            check_version(trt.__version__, '7.0.0', hard=True)  # require tensorrt>=7.0.0
            if device.type == 'cpu':
                device = torch.device('cuda:0')
            Binding = namedtuple('Binding', ('name', 'dtype', 'shape', 'data', 'ptr'))
            logger = trt.Logger(trt.Logger.INFO)
            # Read file
            with open(w, 'rb') as f, trt.Runtime(logger) as runtime:
                meta_len = int.from_bytes(f.read(4), byteorder='little')  # read metadata length
                metadata = json.loads(f.read(meta_len).decode('utf-8'))  # read metadata
                model = runtime.deserialize_cuda_engine(f.read())  # read engine
            context = model.create_execution_context()
            bindings = OrderedDict()
            output_names = []
            fp16 = False  # default updated below
            dynamic = False
            for i in range(model.num_bindings):
                name = model.get_binding_name(i)
                dtype = trt.nptype(model.get_binding_dtype(i))
                if model.binding_is_input(i):
                    if -1 in tuple(model.get_binding_shape(i)):  # dynamic
                        dynamic = True
                        context.set_binding_shape(i, tuple(model.get_profile_shape(0, i)[2]))
                    if dtype == np.float16:
                        fp16 = True
                else:  # output
                    output_names.append(name)
                shape = tuple(context.get_binding_shape(i))
                im = torch.from_numpy(np.empty(shape, dtype=dtype)).to(device)
                bindings[name] = Binding(name, dtype, shape, im, int(im.data_ptr()))
            binding_addrs = OrderedDict((n, d.ptr) for n, d in bindings.items())
            batch_size = bindings['images'].shape[0]  # if dynamic, this is instead max batch size
        elif coreml:  # CoreML
            LOGGER.info(f'Loading {w} for CoreML inference...')
            import coremltools as ct
            model = ct.models.MLModel(w)
            metadata = dict(model.user_defined_metadata)
        elif saved_model:  # TF 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)
            metadata = Path(w) / 'metadata.yaml'
        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

            from ultralytics.engine.exporter import gd_outputs

            def wrap_frozen_graph(gd, inputs, outputs):
                """Wrap frozen graphs for deployment."""
                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()  # TF GraphDef
            with open(w, 'rb') as f:
                gd.ParseFromString(f.read())
            frozen_func = wrap_frozen_graph(gd, inputs='x:0', outputs=gd_outputs(gd))
        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:  # TF 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:  # TFLite
                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
            # Load metadata
            with contextlib.suppress(zipfile.BadZipFile):
                with zipfile.ZipFile(w, 'r') as model:
                    meta_file = model.namelist()[0]
                    metadata = ast.literal_eval(model.read(meta_file).decode('utf-8'))
        elif tfjs:  # TF.js
            raise NotImplementedError('YOLOv8 TF.js inference is not currently supported.')
        elif paddle:  # PaddlePaddle
            LOGGER.info(f'Loading {w} for PaddlePaddle inference...')
            check_requirements('paddlepaddle-gpu' if cuda else 'paddlepaddle')
            import paddle.inference as pdi  # noqa
            w = Path(w)
            if not w.is_file():  # if not *.pdmodel
                w = next(w.rglob('*.pdmodel'))  # get *.pdmodel file from *_paddle_model dir
            config = pdi.Config(str(w), str(w.with_suffix('.pdiparams')))
            if cuda:
                config.enable_use_gpu(memory_pool_init_size_mb=2048, device_id=0)
            predictor = pdi.create_predictor(config)
            input_handle = predictor.get_input_handle(predictor.get_input_names()[0])
            output_names = predictor.get_output_names()
            metadata = w.parents[1] / 'metadata.yaml'
        elif ncnn:  # ncnn
            LOGGER.info(f'Loading {w} for ncnn inference...')
            check_requirements('git+https://github.com/Tencent/ncnn.git' if ARM64 else 'ncnn')  # requires ncnn
            import ncnn as pyncnn
            net = pyncnn.Net()
            net.opt.use_vulkan_compute = cuda
            w = Path(w)
            if not w.is_file():  # if not *.param
                w = next(w.glob('*.param'))  # get *.param file from *_ncnn_model dir
            net.load_param(str(w))
            net.load_model(str(w.with_suffix('.bin')))
            metadata = w.parent / 'metadata.yaml'
        elif triton:  # NVIDIA Triton Inference Server
            check_requirements('tritonclient[all]')
            from ultralytics.utils.triton import TritonRemoteModel
            model = TritonRemoteModel(w)
        else:
            from ultralytics.engine.exporter import export_formats
            raise TypeError(f"model='{w}' is not a supported model format. "
                            'See https://docs.ultralytics.com/modes/predict for help.'
                            f'\n\n{export_formats()}')

        # Load external metadata YAML
        if isinstance(metadata, (str, Path)) and Path(metadata).exists():
            metadata = yaml_load(metadata)
        if metadata:
            for k, v in metadata.items():
                if k in ('stride', 'batch'):
                    metadata[k] = int(v)
                elif k in ('imgsz', 'names', 'kpt_shape') and isinstance(v, str):
                    metadata[k] = eval(v)
            stride = metadata['stride']
            task = metadata['task']
            batch = metadata['batch']
            imgsz = metadata['imgsz']
            names = metadata['names']
            kpt_shape = metadata.get('kpt_shape')
        elif not (pt or triton or nn_module):
            LOGGER.warning(f"WARNING ⚠️ Metadata not found for 'model={weights}'")

        # Check names
        if 'names' not in locals():  # names missing
            names = self._apply_default_class_names(data)
        names = check_class_names(names)

        # Disable gradients
        if pt:
            for p in model.parameters():
                p.requires_grad = False

        self.__dict__.update(locals())  # assign all variables to self

    def forward(self, im, augment=False, visualize=False):
        """
        Runs inference on the YOLOv8 MultiBackend model.

        Args:
            im (torch.Tensor): The image tensor to perform inference on.
            augment (bool): whether to perform data augmentation during inference, defaults to False
            visualize (bool): whether to visualize the output predictions, defaults to False

        Returns:
            (tuple): Tuple containing the raw output tensor, and processed output for visualization (if visualize=True)
        """
        b, ch, h, w = im.shape  # batch, channel, height, width
        if self.fp16 and im.dtype != torch.float16:
            im = im.half()  # to FP16
        if self.nhwc:
            im = im.permute(0, 2, 3, 1)  # torch BCHW to numpy BHWC shape(1,320,192,3)

        if self.pt or self.nn_module:  # PyTorch
            y = self.model(im, augment=augment, visualize=visualize) if augment or visualize else self.model(im)
        elif self.jit:  # TorchScript
            y = self.model(im)
        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.output_names, {self.session.get_inputs()[0].name: im})
        elif self.xml:  # OpenVINO
            im = im.cpu().numpy()  # FP32
            y = list(self.ov_compiled_model(im).values())
        elif self.engine:  # TensorRT
            if self.dynamic and im.shape != self.bindings['images'].shape:
                i = self.model.get_binding_index('images')
                self.context.set_binding_shape(i, im.shape)  # reshape if dynamic
                self.bindings['images'] = self.bindings['images']._replace(shape=im.shape)
                for name in self.output_names:
                    i = self.model.get_binding_index(name)
                    self.bindings[name].data.resize_(tuple(self.context.get_binding_shape(i)))
            s = self.bindings['images'].shape
            assert im.shape == s, f"input size {im.shape} {'>' if self.dynamic else 'not equal to'} max model size {s}"
            self.binding_addrs['images'] = int(im.data_ptr())
            self.context.execute_v2(list(self.binding_addrs.values()))
            y = [self.bindings[x].data for x in sorted(self.output_names)]
        elif self.coreml:  # CoreML
            im = im[0].cpu().numpy()
            im_pil = Image.fromarray((im * 255).astype('uint8'))
            # im = im.resize((192, 320), Image.BILINEAR)
            y = self.model.predict({'image': im_pil})  # coordinates are xywh normalized
            if 'confidence' in y:
                raise TypeError('Ultralytics only supports inference of non-pipelined CoreML models exported with '
                                f"'nms=False', but 'model={w}' has an NMS pipeline created by an 'nms=True' export.")
                # TODO: CoreML NMS inference handling
                # from ultralytics.utils.ops import xywh2xyxy
                # box = xywh2xyxy(y['coordinates'] * [[w, h, w, h]])  # xyxy pixels
                # conf, cls = y['confidence'].max(1), y['confidence'].argmax(1).astype(np.float32)
                # y = np.concatenate((box, conf.reshape(-1, 1), cls.reshape(-1, 1)), 1)
            elif len(y) == 1:  # classification model
                y = list(y.values())
            elif len(y) == 2:  # segmentation model
                y = list(reversed(y.values()))  # reversed for segmentation models (pred, proto)
        elif self.paddle:  # PaddlePaddle
            im = im.cpu().numpy().astype(np.float32)
            self.input_handle.copy_from_cpu(im)
            self.predictor.run()
            y = [self.predictor.get_output_handle(x).copy_to_cpu() for x in self.output_names]
        elif self.ncnn:  # ncnn
            mat_in = self.pyncnn.Mat(im[0].cpu().numpy())
            ex = self.net.create_extractor()
            input_names, output_names = self.net.input_names(), self.net.output_names()
            ex.input(input_names[0], mat_in)
            y = []
            for output_name in output_names:
                mat_out = self.pyncnn.Mat()
                ex.extract(output_name, mat_out)
                y.append(np.array(mat_out)[None])
        elif self.triton:  # NVIDIA Triton Inference Server
            im = im.cpu().numpy()  # torch to numpy
            y = self.model(im)
        else:  # TensorFlow (SavedModel, GraphDef, Lite, Edge TPU)
            im = im.cpu().numpy()
            if self.saved_model:  # SavedModel
                y = self.model(im, training=False) if self.keras else self.model(im)
                if not isinstance(y, list):
                    y = [y]
            elif self.pb:  # GraphDef
                y = self.frozen_func(x=self.tf.constant(im))
                if len(y) == 2 and len(self.names) == 999:  # segments and names not defined
                    ip, ib = (0, 1) if len(y[0].shape) == 4 else (1, 0)  # index of protos, boxes
                    nc = y[ib].shape[1] - y[ip].shape[3] - 4  # y = (1, 160, 160, 32), (1, 116, 8400)
                    self.names = {i: f'class{i}' for i in range(nc)}
            else:  # Lite or Edge TPU
                details = self.input_details[0]
                integer = details['dtype'] in (np.int8, np.int16)  # is TFLite quantized int8 or int16 model
                if integer:
                    scale, zero_point = details['quantization']
                    im = (im / scale + zero_point).astype(details['dtype'])  # de-scale
                self.interpreter.set_tensor(details['index'], im)
                self.interpreter.invoke()
                y = []
                for output in self.output_details:
                    x = self.interpreter.get_tensor(output['index'])
                    if integer:
                        scale, zero_point = output['quantization']
                        x = (x.astype(np.float32) - zero_point) * scale  # re-scale
                    if x.ndim > 2:  # if task is not classification
                        # Denormalize xywh by image size. See https://github.com/ultralytics/ultralytics/pull/1695
                        # xywh are normalized in TFLite/EdgeTPU to mitigate quantization error of integer models
                        x[:, [0, 2]] *= w
                        x[:, [1, 3]] *= h
                    y.append(x)
            # TF segment fixes: export is reversed vs ONNX export and protos are transposed
            if len(y) == 2:  # segment with (det, proto) output order reversed
                if len(y[1].shape) != 4:
                    y = list(reversed(y))  # should be y = (1, 116, 8400), (1, 160, 160, 32)
                y[1] = np.transpose(y[1], (0, 3, 1, 2))  # should be y = (1, 116, 8400), (1, 32, 160, 160)
            y = [x if isinstance(x, np.ndarray) else x.numpy() for x in y]

        # for x in y:
        #     print(type(x), len(x)) if isinstance(x, (list, tuple)) else print(type(x), x.shape)  # debug shapes
        if isinstance(y, (list, tuple)):
            return self.from_numpy(y[0]) if len(y) == 1 else [self.from_numpy(x) for x in y]
        else:
            return self.from_numpy(y)

    def from_numpy(self, x):
        """
        Convert a numpy array to a tensor.

        Args:
            x (np.ndarray): The array to be converted.

        Returns:
            (torch.Tensor): The converted tensor
        """
        return torch.tensor(x).to(self.device) if isinstance(x, np.ndarray) else x

    def warmup(self, imgsz=(1, 3, 640, 640)):
        """
        Warm up the model by running one forward pass with a dummy input.

        Args:
            imgsz (tuple): The shape of the dummy input tensor in the format (batch_size, channels, height, width)

        Returns:
            (None): This method runs the forward pass and don't return any value
        """
        warmup_types = self.pt, self.jit, self.onnx, self.engine, self.saved_model, self.pb, self.triton, self.nn_module
        if any(warmup_types) and (self.device.type != 'cpu' or self.triton):
            im = torch.empty(*imgsz, dtype=torch.half if self.fp16 else torch.float, device=self.device)  # input
            for _ in range(2 if self.jit else 1):  #
                self.forward(im)  # warmup

    @staticmethod
    def _apply_default_class_names(data):
        """Applies default class names to an input YAML file or returns numerical class names."""
        with contextlib.suppress(Exception):
            return yaml_load(check_yaml(data))['names']
        return {i: f'class{i}' for i in range(999)}  # return default if above errors

    @staticmethod
    def _model_type(p='path/to/model.pt'):
        """
        This function takes a path to a model file and returns the model type.

        Args:
            p: path to the model file. Defaults to path/to/model.pt
        """
        # Return model type from model path, i.e. path='path/to/model.onnx' -> type=onnx
        # types = [pt, jit, onnx, xml, engine, coreml, saved_model, pb, tflite, edgetpu, tfjs, paddle]
        from ultralytics.engine.exporter import export_formats
        sf = list(export_formats().Suffix)  # export suffixes
        if not is_url(p, check=False) and not isinstance(p, str):
            check_suffix(p, sf)  # checks
        name = Path(p).name
        types = [s in name for s in sf]
        types[5] |= name.endswith('.mlmodel')  # retain support for older Apple CoreML *.mlmodel formats
        types[8] &= not types[9]  # tflite &= not edgetpu
        if any(types):
            triton = False
        else:
            from urllib.parse import urlsplit
            url = urlsplit(p)
            triton = url.netloc and url.path and url.scheme in {'http', 'grfc'}

        return types + [triton]