/***
    Copyright (C) 2021 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: Commands.cpp
    Date: 2021-6-12
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "Commands.hpp"

namespace Aurora::Console::Commands
{
    struct Command;

    struct CommandDispatch
    {
        Parse::ParsedObject arguments;
        AuSPtr<ICommandSubscriber> callback;

        CommandDispatch(const Parse::ParsedObject &arguments, const AuSPtr<ICommandSubscriber> &callback) : arguments(arguments), callback(callback) {}
    };

    static AuHashMap<AuString, Command> gCommands;
    static AuList<Hooks::LineHook_cb>   gLineCallbacks;
    static AuList<CommandDispatch>      gPendingCommands;
    static AuMutex                      gMutex;
    static AuMutex                      gPendingCommandsMutex;
    static AuOptionalEx<AuWorkerPId_t>  gCommandDispatcher;
          
    struct Command
    {
        AuString tag;
        Parse::ParseObject commandStructure;
        AuSPtr<ICommandSubscriber> callback;

        Command(AuString tag, Parse::ParseObject commandStructure, const AuSPtr<ICommandSubscriber> &callback) : tag(tag), commandStructure(commandStructure), callback(callback) {}
        Command(AuString tag, Parse::ParseObject commandStructure, AuSPtr<ICommandSubscriber> &&callback) : tag(tag), commandStructure(commandStructure), callback(AuMove(callback)) {}
    };

    enum class EDispatchType
    {
        eNow,
        eSys,
        eAsync
    };

    static bool Dispatch(const AuROString &string, EDispatchType type, AuOptionalEx<AuWorkerPId_t> workerId)
    {
        Parse::ParseResult res;
        AuSPtr<ICommandSubscriber> callback;

        // TODO: try catch?

        {
            AU_LOCK_GLOBAL_GUARD(gPendingCommandsMutex);

            {
                AuString tag;
                AuString cmdParse;
                AuMach offset;

                auto commandSplit = string.find(" ");
                if (commandSplit != AuString::npos)
                {
                    tag = string.substr(0, commandSplit);
                    cmdParse = string.substr(commandSplit + 1);
                }
                else
                {
                    tag = string;
                }

                auto cmdItr = gCommands.find(tag);
                if (cmdItr == gCommands.end())
                {
                    AuLogWarn("Command {} does not exist", tag);
                    return false;
                }

                auto const &cmdEntry = cmdItr->second;

                offset = 0;
                Parse::ParseState consumable(AuIO::Character::ProviderFromStringShared(cmdParse, offset));
                auto status = Parse::Parse(consumable, cmdEntry.commandStructure, res);

                if (!status)
                {
                    AuLogWarn("Couldn't parse command {}", string);
                    return false;
                }

                if (type == EDispatchType::eSys)
                {
                    return AuTryInsert(gPendingCommands, CommandDispatch(res.result, cmdEntry.callback));
                }
                else
                {
                    callback = cmdEntry.callback;
                }
            }
        }

        if (type == EDispatchType::eNow)
        {
            callback->OnCommand(res.result);
        }
        else if (workerId)
        {
            Async::DispatchOn(workerId.value(), [=]() -> void
            {
                callback->OnCommand(res.result);
            });
        }

        return true;
    }

    AUKN_SYM void RemoveCommand(const AuROString &tag)
    {
        AU_LOCK_GLOBAL_GUARD(gPendingCommandsMutex);
        AuTryRemove(gCommands, tag);
    }

    AUKN_SYM void AddCommand(const AuROString &tag, const Parse::ParseObject &commandStructure, const AuSPtr<ICommandSubscriber> &callback)
    {
        AU_LOCK_GLOBAL_GUARD(gPendingCommandsMutex);
        SysAssert(callback);
        gCommands.insert(AuMakePair(AuString(tag), Command(AuString(tag), commandStructure, callback)));
    }

    AUKN_SYM bool DispatchCommand(const AuROString &string)
    {
        return Dispatch(string, EDispatchType::eSys, gCommandDispatcher);
    }

    AUKN_SYM bool DispatchCommandThisThread(const AuROString &string)
    {
        return Dispatch(string, EDispatchType::eNow, {});
    }
    
    AUKN_SYM bool DispatchCommandToAsyncRunner(const AuROString &string, Async::WorkerPId_t id)
    {
        return Dispatch(string, EDispatchType::eAsync, id);
    }

    void UpdateDispatcher(AuOptionalEx<AuWorkerPId_t> target)
    {
        AU_LOCK_GLOBAL_GUARD(gMutex);
        AU_LOCK_GUARD(gPendingCommandsMutex);

        // process commands before async app termination
        if ((!target.has_value()))
        {
            auto commands = AuExchange(gPendingCommands, {});
            for (const auto &command : commands)
            {
                command.callback->OnCommand(command.arguments);
            }
        }

        gCommandDispatcher = target;
    }

    static void DispatchCommandsFromThis(const AuList<CommandDispatch> &commands)
    {
        for (const auto &command : commands)
        {
            command.callback->OnCommand(command.arguments);
        }
    }

    void RunCommandFunction(const AuFunction<void()> &func)
    {
        if (!gCommandDispatcher)
        {
            func();
        }
        else
        {
            DispatchOn(gCommandDispatcher.value(), func)->BlockUntilComplete();
        }
    }

    void PumpCommands()
    {
        AU_LOCK_GLOBAL_GUARD(gMutex);
        AuList<CommandDispatch> commands;

        {
            AU_LOCK_GUARD(gPendingCommandsMutex);
            commands = AuExchange(gPendingCommands, {});
            
            if (commands.empty())
            {
                return;
            }
        }
        
        RunCommandFunction([&commands]()
        {
            DispatchCommandsFromThis(commands);
        });
    }
}