//* Copyright 2017 The NXT Authors
//*
//* Licensed under the Apache License, Version 2.0 (the "License");
//* you may not use this file except in compliance with the License.
//* You may obtain a copy of the License at
//*
//*     http://www.apache.org/licenses/LICENSE-2.0
//*
//* Unless required by applicable law or agreed to in writing, software
//* distributed under the License is distributed on an "AS IS" BASIS,
//* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//* See the License for the specific language governing permissions and
//* limitations under the License.

#include "Wire.h"
#include "WireCmd.h"

#include <cassert>
#include <cstring>
#include <memory>
#include <vector>

#include <iostream>

namespace nxt {
namespace wire {

    //* Client side implementation of the API, will serialize everything to memory to send to the server side.
    namespace client {

        class Device;

        void PrintBuilderError(nxtBuilderErrorStatus status, const char* message, nxtCallbackUserdata, nxtCallbackUserdata) {
            if (status == NXT_BUILDER_ERROR_STATUS_SUCCESS || status == NXT_BUILDER_ERROR_STATUS_UNKNOWN) {
                return;
            }

            std::cout << "Got a builder error " << status << ": " << message << std::endl;
        }

        struct BuilderCallbackData {
            void Call(nxtBuilderErrorStatus status, const char* message) {
                if (canCall && callback != nullptr) {
                    canCall = true;
                    callback(status, message, userdata1, userdata2);
                }
            }

            //* For help with development, prints all builder errors by default.
            nxtBuilderErrorCallback callback = PrintBuilderError;
            nxtCallbackUserdata userdata1 = 0;
            nxtCallbackUserdata userdata2 = 0;
            bool canCall = true;
        };

        //* All non-Device objects of the client side have:
        //*  - A pointer to the device to get where to serialize commands
        //*  - The external reference count
        //*  - An ID that is used to refer to this object when talking with the server side
        struct ObjectBase {
            ObjectBase(Device* device, uint32_t refcount, uint32_t id)
                :device(device), refcount(refcount), id(id) {
            }

            Device* device;
            uint32_t refcount;
            uint32_t id;

            BuilderCallbackData builderCallback;
        };

        {% for type in by_category["object"] if not type.name.canonical_case() == "device" %}
            struct {{type.name.CamelCase()}} : ObjectBase {
                using ObjectBase::ObjectBase;
            };
        {% endfor %}

        //* TODO(cwallez@chromium.org): Do something with objects before they are destroyed ?
        //*  - Call still uncalled builder callbacks
        template<typename T>
        class ObjectAllocator {
            public:
                struct ObjectAndSerial {
                    ObjectAndSerial(std::unique_ptr<T> object, uint32_t serial)
                        : object(std::move(object)), serial(serial) {
                    }
                    std::unique_ptr<T> object;
                    uint32_t serial;
                };

                ObjectAllocator(Device* device) : device(device) {
                    // ID 0 is nullptr
                    objects.emplace_back(nullptr, 0);
                }

                ObjectAndSerial* New() {
                    uint32_t id = GetNewId();
                    T* result = new T(device, 1, id);
                    auto object = std::unique_ptr<T>(result);

                    if (id >= objects.size()) {
                        assert(id == objects.size());
                        objects.emplace_back(std::move(object), 0);
                    } else {
                        assert(objects[id].object == nullptr);
                        //* TODO(cwallez@chromium.org): investigate if overflows could cause bad things to happen
                        objects[id].serial++;
                        objects[id].object = std::move(object);
                    }

                    return &objects[id];
                }
                void Free(T* obj) {
                    FreeId(obj->id);
                    objects[obj->id].object = nullptr;
                }

                T* GetObject(uint32_t id) {
                    if (id >= objects.size()) {
                        return nullptr;
                    }
                    return objects[id].object.get();
                }

                uint32_t GetSerial(uint32_t id) {
                    if (id >= objects.size()) {
                        return 0;
                    }
                    return objects[id].serial;
                }

            private:
                uint32_t GetNewId() {
                    if (freeIds.empty()) {
                        return currentId ++;
                    }
                    uint32_t id = freeIds.back();
                    freeIds.pop_back();
                    return id;
                }
                void FreeId(uint32_t id) {
                    freeIds.push_back(id);
                };

                // 0 is an ID reserved to represent nullptr
                uint32_t currentId = 1;
                std::vector<uint32_t> freeIds;
                std::vector<ObjectAndSerial> objects;
                Device* device;
        };

        //* The client wire uses the global NXT device to store its global data such as the serializer
        //* and the object id allocators.
        class Device : public ObjectBase {
            public:
                Device(CommandSerializer* serializer)
                    : ObjectBase(this, 1, 1),
                    {% for type in by_category["object"] if not type.name.canonical_case() == "device" %}
                        {{type.name.camelCase()}}(this),
                    {% endfor %}
                    serializer(serializer) {
                }

                void* GetCmdSpace(size_t size) {
                    return serializer->GetCmdSpace(size);
                }

                {% for type in by_category["object"] if not type.name.canonical_case() == "device" %}
                    ObjectAllocator<{{type.name.CamelCase()}}> {{type.name.camelCase()}};
                {% endfor %}

                nxtDeviceErrorCallback errorCallback = nullptr;
                nxtCallbackUserdata errorUserdata;

            private:
               CommandSerializer* serializer = nullptr;
        };

        //* Implementation of the client API functions.
        {% for type in by_category["object"] %}
            {% set Type = type.name.CamelCase() %}

            {% for method in type.methods %}
                {% set Suffix = as_MethodSuffix(type.name, method.name) %}

                {{as_backendType(method.return_type)}} Client{{Suffix}}(
                    {{-as_backendType(type)}} self
                    {%- for arg in method.arguments -%}
                        , {{as_annotated_backendType(arg)}}
                    {%- endfor -%}
                ) {
                    Device* device = self->device;
                    wire::{{Suffix}}Cmd cmd;

                    //* Create the structure going on the wire on the stack and fill it with the value
                    //* arguments so it can compute its size.
                    {
                        //* Value objects are stored as IDs
                        {% for arg in method.arguments if arg.annotation == "value" %}
                            {% if arg.type.category == "object" %}
                                cmd.{{as_varName(arg.name)}} = {{as_varName(arg.name)}}->id;
                            {% else %}
                                cmd.{{as_varName(arg.name)}} = {{as_varName(arg.name)}};
                            {% endif %}
                        {% endfor %}

                        cmd.self = self->id;

                        //* The length of const char* is considered a value argument.
                        {% for arg in method.arguments if arg.length == "strlen" %}
                            cmd.{{as_varName(arg.name)}}Strlen = strlen({{as_varName(arg.name)}});
                        {% endfor %}
                    }

                    //* Allocate space to send the command and copy the value args over.
                    size_t requiredSize = cmd.GetRequiredSize();
                    auto allocCmd = reinterpret_cast<decltype(cmd)*>(device->GetCmdSpace(requiredSize));
                    *allocCmd = cmd;

                    //* In the allocated space, write the non-value arguments.
                    {% for arg in method.arguments if arg.annotation != "value" %}
                        {% set argName = as_varName(arg.name) %}
                        {% if arg.length == "strlen" %}
                            memcpy(allocCmd->GetPtr_{{argName}}(), {{argName}}, allocCmd->{{argName}}Strlen + 1);
                        {% elif arg.type.category == "object" %}
                            auto {{argName}}Storage = reinterpret_cast<uint32_t*>(allocCmd->GetPtr_{{argName}}());
                            for (size_t i = 0; i < {{as_varName(arg.length.name)}}; i++) {
                                {{argName}}Storage[i] = {{argName}}[i]->id;
                            }
                        {% else %}
                            memcpy(allocCmd->GetPtr_{{argName}}(), {{argName}}, {{as_varName(arg.length.name)}} * sizeof(*{{argName}}));
                        {% endif %}
                    {% endfor %}

                    //* For object creation, store the object ID the client will use for the result.
                    {% if method.return_type.category == "object" %}
                        auto* allocation = self->device->{{method.return_type.name.camelCase()}}.New();

                        {% if type.is_builder %}
                            //* We are in GetResult, so the callback that should be called is the
                            //* currently set one. Copy it over to the created object and prevent the
                            //* builder from calling the callback on destruction.
                            allocation->object->builderCallback = self->builderCallback;
                            self->builderCallback.canCall = false;
                        {% endif %}

                        allocCmd->resultId = allocation->object->id;
                        allocCmd->resultSerial = allocation->serial;
                        return allocation->object.get();
                    {% endif %}
                }
            {% endfor %}

            {% if type.is_builder %}
                void Client{{as_MethodSuffix(type.name, Name("set error callback"))}}({{Type}}* self,
                                                                                      nxtBuilderErrorCallback callback,
                                                                                      nxtCallbackUserdata userdata1,
                                                                                      nxtCallbackUserdata userdata2) {
                    self->builderCallback.callback = callback;
                    self->builderCallback.userdata1 = userdata1;
                    self->builderCallback.userdata2 = userdata2;
                }
            {% endif %}

            {% if not type.name.canonical_case() == "device" %}
                //* When an object's refcount reaches 0, notify the server side of it and delete it.
                void Client{{as_MethodSuffix(type.name, Name("release"))}}({{Type}}* obj) {
                    obj->refcount --;

                    if (obj->refcount > 0) {
                        return;
                    }

                    obj->builderCallback.Call(NXT_BUILDER_ERROR_STATUS_UNKNOWN, "Unknown");

                    wire::{{as_MethodSuffix(type.name, Name("destroy"))}}Cmd cmd;
                    cmd.objectId = obj->id;

                    size_t requiredSize = cmd.GetRequiredSize();
                    auto allocCmd = reinterpret_cast<decltype(cmd)*>(obj->device->GetCmdSpace(requiredSize));
                    *allocCmd = cmd;

                    obj->device->{{type.name.camelCase()}}.Free(obj);
                }

                void Client{{as_MethodSuffix(type.name, Name("reference"))}}({{Type}}* obj) {
                    obj->refcount ++;
                }
            {% endif %}
        {% endfor %}

        void ClientDeviceReference(Device* self) {
        }

        void ClientDeviceRelease(Device* self) {
        }

        void ClientDeviceSetErrorCallback(Device* self, nxtDeviceErrorCallback callback, nxtCallbackUserdata userdata) {
            self->errorCallback = callback;
            self->errorUserdata = userdata;
        }

        nxtProcTable GetProcs() {
            nxtProcTable table;
            {% for type in by_category["object"] %}
                {% for method in native_methods(type) %}
                    table.{{as_varName(type.name, method.name)}} = reinterpret_cast<{{as_cProc(type.name, method.name)}}>(Client{{as_MethodSuffix(type.name, method.name)}});
                {% endfor %}
            {% endfor %}
            return table;
        }

        class Client : public CommandHandler {
            public:
                Client(Device* device) : device(device) {
                }

                const uint8_t* HandleCommands(const uint8_t* commands, size_t size) override {
                    while (size > sizeof(ReturnWireCmd)) {
                        ReturnWireCmd cmdId = *reinterpret_cast<const ReturnWireCmd*>(commands);

                        bool success = false;
                        switch (cmdId) {
                            case ReturnWireCmd::DeviceErrorCallback:
                                success = HandleDeviceErrorCallbackCmd(&commands, &size);
                                break;
                            {% for type in by_category["object"] if type.is_builder %}
                                case ReturnWireCmd::{{type.name.CamelCase()}}ErrorCallback:
                                    success = Handle{{type.name.CamelCase()}}ErrorCallbackCmd(&commands, &size);
                                    break;
                            {% endfor %}
                            default:
                                success = false;
                        }

                        if (!success) {
                            return nullptr;
                        }
                    }

                    if (size != 0) {
                        return nullptr;
                    }

                    return commands;
                }

            private:
                Device* device = nullptr;

                //* Helper function for the getting of the command data in command handlers.
                //* Checks there is enough data left, updates the buffer / size and returns
                //* the command (or nullptr for an error).
                template<typename T>
                static const T* GetCommand(const uint8_t** commands, size_t* size) {
                    if (*size < sizeof(T)) {
                        return nullptr;
                    }

                    const T* cmd = reinterpret_cast<const T*>(*commands);

                    size_t cmdSize = cmd->GetRequiredSize();
                    if (*size < cmdSize) {
                        return nullptr;
                    }

                    *commands += cmdSize;
                    *size -= cmdSize;

                    return cmd;
                }

                bool HandleDeviceErrorCallbackCmd(const uint8_t** commands, size_t* size) {
                    const auto* cmd = GetCommand<ReturnDeviceErrorCallbackCmd>(commands, size);
                    if (cmd == nullptr) {
                        return false;
                    }

                    if (cmd->GetMessage()[cmd->messageStrlen] != '\0') {
                        return false;
                    }

                    if (device->errorCallback != nullptr) {
                        device->errorCallback(cmd->GetMessage(), device->errorUserdata);
                    }

                    return true;
                }

                {% for type in by_category["object"] if type.is_builder %}
                    {% set Type = type.name.CamelCase() %}
                    bool Handle{{Type}}ErrorCallbackCmd(const uint8_t** commands, size_t* size) {
                        const auto* cmd = GetCommand<Return{{Type}}ErrorCallbackCmd>(commands, size);
                        if (cmd == nullptr) {
                            return false;
                        }

                        if (cmd->GetMessage()[cmd->messageStrlen] != '\0') {
                            return false;
                        }

                        auto* builtObject = device->{{type.built_type.name.camelCase()}}.GetObject(cmd->builtObjectId);
                        uint32_t objectSerial = device->{{type.built_type.name.camelCase()}}.GetSerial(cmd->builtObjectId);

                        //* The object might have been deleted or a new object created with the same ID.
                        if (builtObject == nullptr || objectSerial != cmd->builtObjectSerial) {
                            return true;
                        }

                        builtObject->builderCallback.Call(static_cast<nxtBuilderErrorStatus>(cmd->status), cmd->GetMessage());
                        return true;
                    }
                {% endfor %}
        };

    }

    CommandHandler* NewClientDevice(nxtProcTable* procs, nxtDevice* device, CommandSerializer* serializer) {
        auto clientDevice = new client::Device(serializer);

        *device = reinterpret_cast<nxtDeviceImpl*>(clientDevice);
        *procs = client::GetProcs();

        return new client::Client(clientDevice);
    }

}
}