use core::ffi::c_void;
use core::ptr::NonNull;
use objc2::{extern_protocol, rc::Retained, runtime::ProtocolObject};

use crate::{MTLBuffer, MTLResource, MTLResourceID};

use super::{MTLTensorDataType, MTLTensorExtents, MTLTensorUsage};

extern_protocol!(
    /// A resource representing a multi-dimensional array that you can use with machine learning workloads.
    ///
    /// See also Apple's documentation: `https://developer.apple.com/documentation/metal/mtltensor?language=objc`
    pub unsafe trait MTLTensor: MTLResource {
        /// A handle that represents the GPU resource, which you can store in an argument buffer.
        #[unsafe(method(gpuResourceID))]
        #[unsafe(method_family = none)]
        fn gpu_resource_id(&self) -> MTLResourceID;

        /// A buffer instance this tensor shares its storage with or nil if this tensor does not wrap an underlying buffer.
        #[unsafe(method(buffer))]
        #[unsafe(method_family = none)]
        fn buffer(&self) -> Option<Retained<ProtocolObject<dyn MTLBuffer>>>;

        /// An offset, in bytes, into the buffer instance this tensor shares its storage with, or zero if this tensor does not wrap an underlying buffer.
        #[unsafe(method(bufferOffset))]
        #[unsafe(method_family = none)]
        fn buffer_offset(&self) -> usize;

        /// An array of strides, in elements, one for each dimension of this tensor.
        ///
        /// This property only applies if this tensor shares its storage with a buffer, otherwise it's nil.
        #[unsafe(method(strides))]
        #[unsafe(method_family = none)]
        fn strides(&self) -> Option<Retained<MTLTensorExtents>>;

        /// An array of sizes, in elements, one for each dimension of this tensor.
        #[unsafe(method(dimensions))]
        #[unsafe(method_family = none)]
        fn dimensions(&self) -> Retained<MTLTensorExtents>;

        /// An underlying data format of this tensor.
        #[unsafe(method(dataType))]
        #[unsafe(method_family = none)]
        fn data_type(&self) -> MTLTensorDataType;

        /// A set of contexts in which you can use this tensor.
        #[unsafe(method(usage))]
        #[unsafe(method_family = none)]
        fn usage(&self) -> MTLTensorUsage;

        /// Replaces the contents of a slice of this tensor with data you provide.
        ///
        /// Parameters:
        ///  - sliceOrigin: An array of offsets, in elements, to the first element of the slice that this method writes data to.
        ///  - sliceDimensions: An array of sizes, in elements, of the slice this method writes data to.
        ///  - bytes: A pointer to bytes of data that this method copies into the slice you specify with `sliceOrigin` and `sliceDimensions`.
        ///  - strides: An array of strides, in elements, that describes the layout of the data in `bytes`. You are responsible for ensuring `strides` meets the following requirements:
        ///    - Elements of `strides` are in monotonically non-decreasing order.
        ///    - For any `i` larger than zero, `strides[i]` is greater than or equal to `strides[i-1] * dimensions[i-1]`.
        #[unsafe(method(replaceSliceOrigin:sliceDimensions:withBytes:strides:))]
        #[unsafe(method_family = none)]
        fn replace_slice_origin_slice_dimensions_with_bytes_strides(
            &self,
            slice_origin: &MTLTensorExtents,
            slice_dimensions: &MTLTensorExtents,
            bytes: NonNull<c_void>,
            strides: &MTLTensorExtents,
        );

        /// Copies the data corresponding to a slice of this tensor into a pointer you provide.
        ///
        /// Parameters:
        ///  - bytes: A pointer to bytes of data that this method copies into the slice you specify with `sliceOrigin` and `sliceDimensions`.
        ///  - strides: An array of strides, in elements, that describes the layout of the data in `bytes`. You are responsible for ensuring `strides` meets the following requirements:
        ///    - Elements of `strides` are in monotonically non-decreasing order.
        ///    - For any `i` larger than zero, `strides[i]` is greater than or equal to `strides[i-1] * dimensions[i-1]`.
        ///  - sliceOrigin: An array of offsets, in elements, to the first element of the slice that this method reads data from.
        ///  - sliceDimensions: An array of sizes, in elements, of the slice this method reads data from.
        #[unsafe(method(getBytes:strides:fromSliceOrigin:sliceDimensions:))]
        #[unsafe(method_family = none)]
        fn get_bytes_strides_from_slice_origin_slice_dimensions(
            &self,
            bytes: NonNull<c_void>,
            strides: &MTLTensorExtents,
            slice_origin: &MTLTensorExtents,
            slice_dimensions: &MTLTensorExtents,
        );
    }
);
