// ----------------------------------------------------------------------------
// -                        Open3D: www.open3d.org                            -
// ----------------------------------------------------------------------------
// Copyright (c) 2018-2023 www.open3d.org
// SPDX-License-Identifier: MIT
// ----------------------------------------------------------------------------

#pragma once

#include <array>
#include <cstring>
#include <map>
#include <msgpack.hpp>
#include <string>
#include <vector>

#include "open3d/core/Tensor.h"

namespace open3d {
namespace io {
namespace rpc {
namespace messages {

inline std::string EndiannessStr() {
    auto IsLittleEndian = []() -> bool {
        uint32_t a = 1;
        uint8_t b;
        // Use memcpy as a reliable way to access a single byte.
        // Other approaches, e.g. union, often rely on undefined behaviour.
        std::memcpy(&b, &a, sizeof(uint8_t));
        return b == 1;
    };

    return IsLittleEndian() ? "<" : ">";
}

/// Template function for converting types to their string representation.
/// E.g. TypeStr<float>() -> "<f4"
template <class T>
inline std::string TypeStr() {
    return "";
}
template <>
inline std::string TypeStr<float>() {
    return EndiannessStr() + "f4";
}
template <>
inline std::string TypeStr<double>() {
    return EndiannessStr() + "f8";
}
template <>
inline std::string TypeStr<int8_t>() {
    return "|i1";
}
template <>
inline std::string TypeStr<int16_t>() {
    return EndiannessStr() + "i2";
}
template <>
inline std::string TypeStr<int32_t>() {
    return EndiannessStr() + "i4";
}
template <>
inline std::string TypeStr<int64_t>() {
    return EndiannessStr() + "i8";
}
template <>
inline std::string TypeStr<uint8_t>() {
    return "|u1";
}
template <>
inline std::string TypeStr<uint16_t>() {
    return EndiannessStr() + "u2";
}
template <>
inline std::string TypeStr<uint32_t>() {
    return EndiannessStr() + "u4";
}
template <>
inline std::string TypeStr<uint64_t>() {
    return EndiannessStr() + "u8";
}

/// Array structure inspired by msgpack_numpy but not directly compatible
/// because they use bin-type for the map keys and we must use string.
/// This structure does not have ownership of the data.
///
/// The following code can be used in python to create a compatible dict
///
///   def numpy_to_Array(arr):
///       if isinstance(arr, np.ndarray):
///           return {'type': arr.dtype.str,
///                   'shape': arr.shape,
///                   'data': arr.tobytes()}
///       raise Exception('object is not a numpy array')
///
///
/// This codes converts the dict back to numpy.ndarray
///
///   def Array_to_numpy(dic):
///       return np.frombuffer(dic['data'],
///       dtype=np.dtype(dic['type'])).reshape(dic['shape'])
///
struct Array {
    static std::string MsgId() { return "array"; }

    /// Creates an Array from a pointer. The caller is responsible for keeping
    /// the pointer valid during the lifetime of the Array object.
    template <class T>
    static Array FromPtr(const T* const ptr,
                         const std::vector<int64_t>& shape) {
        Array arr;
        arr.type = TypeStr<T>();
        arr.shape = shape;
        arr.data.ptr = (const char*)ptr;
        int64_t num = 1;
        for (int64_t n : shape) num *= n;
        arr.data.size = uint32_t(sizeof(T) * num);
        return arr;
    }

    /// Creates an Array from a Tensor. This will copy the tensor to
    /// contiguous CPU memory if necessary and the returned array will keep
    /// a reference.
    static Array FromTensor(const core::Tensor& tensor) {
        // We require the tensor to be contiguous and to use the CPU.
        auto t = tensor.To(core::Device("CPU:0")).Contiguous();
        auto a = DISPATCH_DTYPE_TO_TEMPLATE(t.GetDtype(), [&]() {
            auto arr = messages::Array::FromPtr(
                    (scalar_t*)t.GetDataPtr(),
                    static_cast<std::vector<int64_t>>(t.GetShape()));
            arr.tensor_ = t;
            return arr;
        });
        return a;
    }

    // Object for keeping a reference to the tensor. not meant to be serialized.
    core::Tensor tensor_;

    std::string type;
    std::vector<int64_t> shape;
    msgpack::type::raw_ref data;

    template <class T>
    const T* Ptr() const {
        return (T*)data.ptr;
    }

    /// Checks the rank of the shape.
    /// Returns false on mismatch and appends an error description to errstr.
    bool CheckRank(const std::vector<int>& expected_ranks,
                   std::string& errstr) const {
        for (auto rank : expected_ranks) {
            if (shape.size() == size_t(rank)) return true;
        }
        errstr += " expected rank to be in (";
        for (auto rank : expected_ranks) {
            errstr += std::to_string(rank) + ", ";
        }
        errstr += std::string(")") + " but got shape [";
        for (auto d : shape) {
            errstr += std::to_string(d) + ", ";
        }
        errstr += "]";
        return false;
    }
    bool CheckRank(const std::vector<int>& expected_ranks) const {
        std::string _;
        return CheckRank(expected_ranks, _);
    }

    /// Checks the shape against the expected shape. Use -1 in the expected
    /// shape to allow arbitrary values.
    /// Returns false on mismatch and appends an error description to errstr.
    bool CheckShape(const std::vector<int64_t>& expected_shape,
                    std::string& errstr) const {
        if (!CheckRank({int(expected_shape.size())}, errstr)) {
            return false;
        }

        for (size_t i = 0; i < expected_shape.size(); ++i) {
            int64_t d_expected = expected_shape[i];
            int64_t d = shape[i];
            if ((d_expected != -1 && d_expected != d) || d < 0) {
                errstr += " expected shape [";
                for (auto d : expected_shape) {
                    if (d != -1) {
                        errstr += "?, ";
                    } else {
                        errstr += std::to_string(d) + ", ";
                    }
                }
                errstr += "] but got [";
                for (auto d : shape) {
                    errstr += std::to_string(d) + ", ";
                }
                errstr += "]";
                return false;
            }
        }
        return true;
    }
    bool CheckShape(const std::vector<int64_t>& expected_shape) const {
        std::string _;
        return CheckShape(expected_shape, _);
    }

    /// Checks for a non empty array.
    /// Returns false if the array is empty and appends an error description to
    /// errstr.
    bool CheckNonEmpty(std::string& errstr) const {
        int64_t n = 1;
        for (auto d : shape) n *= d;
        if (0 == n || shape.empty()) {
            errstr += " expected non empty array but got array with shape [";
            for (auto d : shape) {
                errstr += std::to_string(d) + ", ";
            }
            errstr += "]";
            return false;
        }
        return true;
    }
    bool CheckNonEmpty() const {
        std::string _;
        return CheckNonEmpty(_);
    }

    /// Checks the data type of the array.
    /// Returns false if the type is not in the list of expected types and
    /// appends an error description to errstr.
    bool CheckType(const std::vector<std::string>& expected_types,
                   std::string& errstr) const {
        for (const auto& t : expected_types) {
            if (t == type) return true;
        }
        errstr += " expected array type to be one of (";
        for (const auto& t : expected_types) {
            errstr += t + ", ";
        }
        errstr += ") but got " + type;
        return false;
    }
    bool CheckType(const std::vector<std::string>& expected_types) const {
        std::string _;
        return CheckType(expected_types, _);
    }

    // macro for creating the serialization/deserialization code
    MSGPACK_DEFINE_MAP(type, shape, data);
};

/// struct for storing MeshData, e.g., PointClouds, TriangleMesh, ..
struct MeshData {
    static std::string MsgId() { return "mesh_data"; }

    /// The original Open3D geometry type from which the MeshData object has
    /// been created. This is one of "PointCloud", "LineSet", "TriangleMesh". If
    /// this field is empty Open3D will infer the type based on the presence of
    /// lines and faces.
    std::string o3d_type;

    /// shape must be [num_verts,3]
    Array vertices;
    /// stores arbitrary attributes for each vertex, hence the first dim must
    /// be num_verts
    std::map<std::string, Array> vertex_attributes;

    /// This array stores vertex indices to define faces.
    /// The array can be of rank 1 or 2.
    /// An array of rank 2 with shape [num_faces,n] defines num_faces n-gons.
    /// If the rank of the array is 1 then polys of different lengths are stored
    /// sequentially. Each polygon is stored as a sequence 'n i1 i2 ... in' with
    /// n>=3. The type of the array must be int32_t or int64_t
    Array faces;
    /// stores arbitrary attributes for each face
    std::map<std::string, Array> face_attributes;

    /// This array stores vertex indices to define lines.
    /// The array can be of rank 1 or 2.
    /// An array of rank 2 with shape [num_lines,n] defines num_lines linestrips
    /// with n vertices. If the rank of the array is 1 then linestrips with
    /// different number of vertices are stored sequentially. Each linestrip is
    /// stored as a sequence 'n i1 i2 ... in' with n>=2. The type of the array
    /// must be int32_t or int64_t
    Array lines;
    /// stores arbitrary attributes for each line
    std::map<std::string, Array> line_attributes;

    /// Material for DrawableGeometry
    std::string material = "";
    /// Material scalar properties
    std::map<std::string, float> material_scalar_attributes;
    /// Material vector[4] properties
    std::map<std::string, std::array<float, 4>> material_vector_attributes;
    /// map of arrays that can be interpreted as textures
    std::map<std::string, Array> texture_maps;

    void SetO3DTypeToPointCloud() { o3d_type = "PointCloud"; }
    void SetO3DTypeToLineSet() { o3d_type = "LineSet"; }
    void SetO3DTypeToTriangleMesh() { o3d_type = "TriangleMesh"; }

    bool O3DTypeIsPointCloud() const { return o3d_type == "PointCloud"; }
    bool O3DTypeIsLineSet() const { return o3d_type == "LineSet"; }
    bool O3DTypeIsTriangleMesh() const { return o3d_type == "TriangleMesh"; }

    bool CheckVertices(std::string& errstr) const {
        if (vertices.shape.empty()) return true;
        std::string tmp = "invalid vertices array:";
        bool status = vertices.CheckNonEmpty(tmp) &&
                      vertices.CheckShape({-1, 3}, tmp);
        if (!status) errstr += tmp;
        return status;
    }

    bool CheckFaces(std::string& errstr) const {
        if (faces.shape.empty()) return true;

        std::string tmp = "invalid faces array:";

        bool status = faces.CheckRank({1, 2}, tmp);
        if (!status) {
            errstr += tmp;
            return false;
        }

        status = faces.CheckType({TypeStr<int32_t>(), TypeStr<int64_t>()}, tmp);
        if (!status) {
            errstr += tmp;
            return false;
        }

        if (faces.CheckRank({1, 2})) {
            status = faces.CheckNonEmpty(tmp);
            if (!status) {
                errstr += tmp;
                return false;
            }
        }

        if (faces.CheckRank({2})) {
            status = faces.shape[1] > 2;
            tmp += " expected shape [?, >2] but got [" +
                   std::to_string(faces.shape[0]) + ", " +
                   std::to_string(faces.shape[1]) + "]";
            if (!status) {
                errstr += tmp;
                return false;
            }
        }
        return status;
    }

    bool CheckO3DType(std::string& errstr) const {
        if (o3d_type.empty() || O3DTypeIsPointCloud() || O3DTypeIsLineSet() ||
            O3DTypeIsTriangleMesh()) {
            return true;
        } else {
            errstr +=
                    " invalid o3d_type. Expected 'PointCloud', 'TriangleMesh', "
                    "or 'LineSet' but got '" +
                    o3d_type + "'.";
            return false;
        }
    }

    bool CheckMessage(std::string& errstr) const {
        std::string tmp = "invalid mesh_data message:";
        bool status =
                CheckO3DType(tmp) && CheckVertices(tmp) && CheckFaces(tmp);
        if (!status) errstr += tmp;
        return status;
    }

    MSGPACK_DEFINE_MAP(o3d_type,
                       vertices,
                       vertex_attributes,
                       faces,
                       face_attributes,
                       lines,
                       line_attributes,
                       material,
                       material_scalar_attributes,
                       material_vector_attributes,
                       texture_maps);
};

/// struct for defining a "set_mesh_data" message, which adds or replaces mesh
/// data.
struct SetMeshData {
    static std::string MsgId() { return "set_mesh_data"; }

    SetMeshData() : time(0) {}

    /// Path defining the location in the scene tree.
    std::string path;
    /// The time associated with this data
    int32_t time;
    /// The layer for this data
    std::string layer;

    /// The data to be set
    MeshData data;

    MSGPACK_DEFINE_MAP(path, time, layer, data);
};

/// struct for defining a "get_mesh_data" message, which requests mesh data.
struct GetMeshData {
    static std::string MsgId() { return "get_mesh_data"; }

    GetMeshData() : time(0) {}

    /// Path defining the location in the scene tree.
    std::string path;
    /// The time for which to return the data
    int32_t time;
    /// The layer for which to return the data
    std::string layer;

    MSGPACK_DEFINE_MAP(path, time, layer);
};

/// struct for storing camera data
struct CameraData {
    static std::string MsgId() { return "camera_data"; }

    CameraData() : width(0), height(0) {}

    // extrinsic parameters defining the world to camera transform, i.e.,
    // X_cam = X_world * R + t

    /// rotation R as quaternion [x,y,z,w]
    std::array<double, 4> R;
    /// translation
    std::array<double, 3> t;

    /// intrinsic parameters following colmap's convention, e.g.
    ///   intrinsic_model = "SIMPLE_RADIAL";
    ///   intrinsic_parameters = {f, cx, cy, k};
    std::string intrinsic_model;
    std::vector<double> intrinsic_parameters;

    /// image dimensions in pixels
    int width;
    int height;

    /// map of arrays that can be interpreted as camera images
    std::map<std::string, Array> images;

    MSGPACK_DEFINE_MAP(
            R, t, intrinsic_model, intrinsic_parameters, width, height, images);
};

/// struct for defining a "set_camera_data" message, which adds or replaces a
/// camera in the scene tree.
struct SetCameraData {
    static std::string MsgId() { return "set_camera_data"; }

    SetCameraData() : time(0) {}

    /// Path defining the location in the scene tree.
    std::string path;
    /// The time for which to return the data
    int32_t time;
    /// The layer for which to return the data
    std::string layer;

    /// The data to be set
    CameraData data;

    MSGPACK_DEFINE_MAP(path, time, layer, data);
};

/// struct for defining a "set_time" message, which sets the current time
/// to the specified value.
struct SetTime {
    static std::string MsgId() { return "set_time"; }
    SetTime() : time(0) {}
    int32_t time;

    MSGPACK_DEFINE_MAP(time);
};

/// struct for defining a "set_active_camera" message, which sets the active
/// camera as the object with the specified path in the scene tree.
struct SetActiveCamera {
    static std::string MsgId() { return "set_active_camera"; }
    std::string path;

    MSGPACK_DEFINE_MAP(path);
};

/// struct for defining a "set_properties" message, which sets properties for
/// the object in the scene tree
struct SetProperties {
    static std::string MsgId() { return "set_properties"; }
    std::string path;

    // application specific members go here.

    MSGPACK_DEFINE_MAP(path);
};

/// struct for defining a "request" message, which describes the subsequent
/// message by storing the msg_id.
struct Request {
    std::string msg_id;
    MSGPACK_DEFINE_MAP(msg_id);
};

/// struct for defining a "reply" message, which describes the subsequent
/// message by storing the msg_id.
struct Reply {
    std::string msg_id;
    MSGPACK_DEFINE_MAP(msg_id);
};

/// struct for defining a "status" message, which will be used for returning
/// error codes or returning code 0 if the call does not return something else.
struct Status {
    static std::string MsgId() { return "status"; }

    Status() : code(0) {}
    Status(int code, const std::string& str) : code(code), str(str) {}
    static Status OK() { return Status(); }
    static Status ErrorUnsupportedMsgId() {
        return Status(1, "unsupported msg_id");
    }
    static Status ErrorUnpackingFailed() {
        return Status(2, "error during unpacking");
    }
    static Status ErrorProcessingMessage() {
        return Status(3, "error while processing message");
    }

    /// return code. 0 means everything is OK.
    int32_t code;
    /// string representation of the code
    std::string str;

    MSGPACK_DEFINE_MAP(code, str);
};

}  // namespace messages
}  // namespace rpc
}  // namespace io
}  // namespace open3d