/*
    Copyright 2016-2022 melonDS team

    This file is part of melonDS.

    melonDS is free software: you can redistribute it and/or modify it under
    the terms of the GNU General Public License as published by the Free
    Software Foundation, either version 3 of the License, or (at your option)
    any later version.

    melonDS is distributed in the hope that it will be useful, but WITHOUT ANY
    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
    FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

    You should have received a copy of the GNU General Public License along
    with melonDS. If not, see http://www.gnu.org/licenses/.
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <queue>

#include <enet/enet.h>
#include <SDL2/SDL.h>

#include <QStandardItemModel>

#include "LAN.h"
#include "Config.h"
#include "main.h"

#include "ui_LANStartHostDialog.h"
#include "ui_LANStartClientDialog.h"
#include "ui_LANDialog.h"


extern EmuThread* emuThread;
LANDialog* lanDlg;


LANStartHostDialog::LANStartHostDialog(QWidget* parent) : QDialog(parent), ui(new Ui::LANStartHostDialog)
{
    ui->setupUi(this);
    setAttribute(Qt::WA_DeleteOnClose);

    // TODO: remember the last setting? so this doesn't suck massively
    // we could also remember the player name (and auto-init it from the firmware name or whatever)
    ui->sbNumPlayers->setRange(2, 16);
    ui->sbNumPlayers->setValue(16);
}

LANStartHostDialog::~LANStartHostDialog()
{
    delete ui;
}

void LANStartHostDialog::done(int r)
{
    if (r == QDialog::Accepted)
    {
        std::string player = ui->txtPlayerName->text().toStdString();
        int numplayers = ui->sbNumPlayers->value();

        // TODO validate input!!

        lanDlg = LANDialog::openDlg(parentWidget());

        LAN::StartHost(player.c_str(), numplayers);
    }

    QDialog::done(r);
}


LANStartClientDialog::LANStartClientDialog(QWidget* parent) : QDialog(parent), ui(new Ui::LANStartClientDialog)
{
    ui->setupUi(this);
    setAttribute(Qt::WA_DeleteOnClose);
}

LANStartClientDialog::~LANStartClientDialog()
{
    delete ui;
}

void LANStartClientDialog::done(int r)
{
    if (r == QDialog::Accepted)
    {
        std::string player = ui->txtPlayerName->text().toStdString();
        std::string host = ui->txtIPAddress->text().toStdString();

        // TODO validate input!!

        lanDlg = LANDialog::openDlg(parentWidget());

        LAN::StartClient(player.c_str(), host.c_str());
    }

    QDialog::done(r);
}


LANDialog::LANDialog(QWidget* parent) : QDialog(parent), ui(new Ui::LANDialog)
{
    ui->setupUi(this);
    setAttribute(Qt::WA_DeleteOnClose);

    QStandardItemModel* model = new QStandardItemModel();
    ui->tvPlayerList->setModel(model);

    connect(this, &LANDialog::sgUpdatePlayerList, this, &LANDialog::doUpdatePlayerList);
}

LANDialog::~LANDialog()
{
    delete ui;
}

void LANDialog::done(int r)
{
    // ???

    QDialog::done(r);
}

void LANDialog::updatePlayerList(LAN::Player* players, int num)
{
    emit sgUpdatePlayerList(players, num);
}

void LANDialog::doUpdatePlayerList(LAN::Player* players, int num)
{
    QStandardItemModel* model = (QStandardItemModel*)ui->tvPlayerList->model();

    model->clear();
    model->setRowCount(num);

    // TODO: remove IP column in final product

    const QStringList header = {"#", "Player", "Status", "Ping", "IP"};
    model->setHorizontalHeaderLabels(header);

    for (int i = 0; i < num; i++)
    {
        LAN::Player* player = &players[i];

        QString id = QString("%0").arg(player->ID+1);
        model->setItem(i, 0, new QStandardItem(id));

        QString name = player->Name;
        model->setItem(i, 1, new QStandardItem(name));

        QString status;
        switch (player->Status)
        {
        case 1: status = ""; break;
        case 2: status = "Host"; break;
        default: status = "ded"; break;
        }
        model->setItem(i, 2, new QStandardItem(status));

        // TODO: ping
        model->setItem(i, 3, new QStandardItem("x"));

        char ip[32];
        u32 addr = player->Address;
        sprintf(ip, "%d.%d.%d.%d", addr&0xFF, (addr>>8)&0xFF, (addr>>16)&0xFF, addr>>24);
        model->setItem(i, 4, new QStandardItem(ip));
    }
}


namespace LAN
{

struct MPPacketHeader
{
    u32 Magic;
    u32 SenderID;
    u32 Type;       // 0=regular 1=CMD 2=reply 3=ack
    u32 Length;
    u64 Timestamp;
};

const int kLANPort = 7064;

bool Active;
bool IsHost;

ENetHost* Host;
ENetPeer* RemotePeers[16];

Player Players[16];
int NumPlayers;
int MaxPlayers;

u16 ConnectedBitmask;

Player MyPlayer;
u32 HostAddress;
bool Lag;

int MPRecvTimeout;
std::queue<ENetPacket*> RXQueue;


bool Init()
{
    Active = false;
    IsHost = false;
    Host = nullptr;
    Lag = false;

    memset(RemotePeers, 0, sizeof(RemotePeers));
    memset(Players, 0, sizeof(Players));
    NumPlayers = 0;
    MaxPlayers = 0;

    ConnectedBitmask = 0;

    MPRecvTimeout = 25;

    // TODO we init enet here but also in Netplay
    // that is redundant
    if (enet_initialize() != 0)
    {
        printf("enet shat itself :(\n");
        return false;
    }

    printf("enet init OK\n");
    return true;
}

void DeInit()
{
    // TODO: cleanup resources properly!!

    enet_deinitialize();
}


void StartHost(const char* playername, int numplayers)
{
    ENetAddress addr;
    addr.host = ENET_HOST_ANY;
    addr.port = kLANPort;

    Host = enet_host_create(&addr, 16, 2, 0, 0);
    if (!Host)
    {
        // TODO handle this gracefully
        printf("host shat itself :(\n");
        return;
    }

    Player* player = &Players[0];
    memset(player, 0, sizeof(Player));
    player->ID = 0;
    strncpy(player->Name, playername, 31);
    player->Status = 2;
    player->Address = 0x0100007F;
    NumPlayers = 1;
    MaxPlayers = numplayers;
    memcpy(&MyPlayer, player, sizeof(Player));

    HostAddress = 0x0100007F;

    Active = true;
    IsHost = true;

    lanDlg->updatePlayerList(Players, NumPlayers);
}

void StartClient(const char* playername, const char* host)
{
    Host = enet_host_create(nullptr, 16, 2, 0, 0);
    if (!Host)
    {
        // TODO handle this gracefully
        printf("client shat itself :(\n");
        return;
    }

    printf("client created, connecting (%s, %s:%d)\n", playername, host, kLANPort);

    ENetAddress addr;
    enet_address_set_host(&addr, host);
    addr.port = kLANPort;
    ENetPeer* peer = enet_host_connect(Host, &addr, 2, 0);
    if (!peer)
    {
        printf("connect shat itself :(\n");
        return;
    }

    ENetEvent event;
    bool conn = false;
    if (enet_host_service(Host, &event, 5000) > 0)
    {
        if (event.type == ENET_EVENT_TYPE_CONNECT)
        {
            printf("connected!\n");
            conn = true;
        }
    }

    if (!conn)
    {
        printf("connection failed\n");
        enet_peer_reset(peer);
        return;
    }

    Player* player = &MyPlayer;
    memset(player, 0, sizeof(Player));
    player->ID = 0;
    strncpy(player->Name, playername, 31);
    player->Status = 3;

    HostAddress = addr.host;

    Active = true;
    IsHost = false;
}


void ProcessHostEvent(ENetEvent& event)
{
    switch (event.type)
    {
    case ENET_EVENT_TYPE_CONNECT:
        {
            if ((NumPlayers >= MaxPlayers) || (NumPlayers >= 16))
            {
                // game is full, reject connection
                enet_peer_disconnect(event.peer, 0);
                break;
            }

            // client connected; assign player number

            int id;
            for (id = 0; id < 16; id++)
            {
                if (id >= NumPlayers) break;
                if (Players[id].Status == 0) break;
            }

            if (id < 16)
            {
                u8 cmd[3];
                cmd[0] = 0x01;
                cmd[1] = (u8)id;
                cmd[2] = MaxPlayers;
                ENetPacket* pkt = enet_packet_create(cmd, 3, ENET_PACKET_FLAG_RELIABLE);
                enet_peer_send(event.peer, 0, pkt);

                Players[id].ID = id;
                Players[id].Status = 3;
                Players[id].Address = event.peer->address.host;
                event.peer->data = &Players[id];
                NumPlayers++;

                RemotePeers[id] = event.peer;
            }
            else
            {
                // ???
                enet_peer_disconnect(event.peer, 0);
            }
        }
        break;

    case ENET_EVENT_TYPE_DISCONNECT:
        {
            // TODO
            printf("disco\n");
        }
        break;

    case ENET_EVENT_TYPE_RECEIVE:
        {
            if (event.packet->dataLength < 1) break;

            u8* data = (u8*)event.packet->data;
            switch (data[0])
            {
            case 0x02: // client sending player info
                {
                    if (event.packet->dataLength != (1+sizeof(Player))) break;

                    Player player;
                    memcpy(&player, &data[1], sizeof(Player));
                    player.Name[31] = '\0';

                    Player* hostside = (Player*)event.peer->data;
                    if (player.ID != hostside->ID)
                    {
                        printf("what??? %d =/= %d\n", player.ID, hostside->ID);
                        // TODO: disconnect
                        break;
                    }

                    player.Status = 1;
                    player.Address = event.peer->address.host;
                    memcpy(hostside, &player, sizeof(Player));

                    // broadcast updated player list
                    u8 cmd[2+sizeof(Players)];
                    cmd[0] = 0x03;
                    cmd[1] = (u8)NumPlayers;
                    memcpy(&cmd[2], Players, sizeof(Players));
                    ENetPacket* pkt = enet_packet_create(cmd, 2+sizeof(Players), ENET_PACKET_FLAG_RELIABLE);
                    enet_host_broadcast(Host, 0, pkt);

                    lanDlg->updatePlayerList(Players, NumPlayers);
                }
                break;

            case 0x04: // player connected
                {
                    if (event.packet->dataLength != 2) break;
                    if (data[1] > 15) break;

                    ConnectedBitmask |= (1<<data[1]);
                }
                break;

            case 0x05: // player disconnected
                {
                    if (event.packet->dataLength != 2) break;
                    if (data[1] > 15) break;

                    ConnectedBitmask &= ~(1<<data[1]);
                }
                break;
            }

            enet_packet_destroy(event.packet);
        }
        break;
    }
}

void ProcessClientEvent(ENetEvent& event)
{
    switch (event.type)
    {
    case ENET_EVENT_TYPE_CONNECT:
        {
            // another client is establishing a direct connection to us

            int playerid = -1;
            for (int i = 0; i < 16; i++)
            {
                Player* player = &Players[i];
                if (player->ID == MyPlayer.ID) continue;
                if (player->Status != 1) continue;

                if (player->Address == event.peer->address.host)
                {
                    playerid = i;
                    break;
                }
            }

            if (playerid < 0)
            {
                enet_peer_disconnect(event.peer, 0);
                break;
            }

            RemotePeers[playerid] = event.peer;
        }
        break;

    case ENET_EVENT_TYPE_DISCONNECT:
        {
            // TODO
            printf("shma\n");
        }
        break;

    case ENET_EVENT_TYPE_RECEIVE:
        {
            if (event.packet->dataLength < 1) break;

            u8* data = (u8*)event.packet->data;
            switch (data[0])
            {
            case 0x01: // host sending player ID
                {
                    if (event.packet->dataLength != 3) break;

                    MaxPlayers = data[2];

                    // send player information
                    MyPlayer.ID = data[1];
                    u8 cmd[1+sizeof(Player)];
                    cmd[0] = 0x02;
                    memcpy(&cmd[1], &MyPlayer, sizeof(Player));
                    ENetPacket* pkt = enet_packet_create(cmd, 1+sizeof(Player), ENET_PACKET_FLAG_RELIABLE);
                    enet_peer_send(event.peer, 0, pkt);
                }
                break;

            case 0x03: // host sending player list
                {
                    if (event.packet->dataLength != (2+sizeof(Players))) break;
                    if (data[1] > 16) break;

                    NumPlayers = data[1];
                    memcpy(Players, &data[2], sizeof(Players));
                    for (int i = 0; i < 16; i++)
                    {
                        Players[i].Name[31] = '\0';
                    }

                    lanDlg->updatePlayerList(Players, NumPlayers);

                    // establish connections to any new clients
                    for (int i = 0; i < 16; i++)
                    {
                        Player* player = &Players[i];
                        if (player->ID == MyPlayer.ID) continue;
                        if (player->Status != 1) continue;

                        if (!RemotePeers[i])
                        {
                            ENetAddress peeraddr;
                            peeraddr.host = player->Address;
                            peeraddr.port = kLANPort;
                            ENetPeer* peer = enet_host_connect(Host, &peeraddr, 2, 0);
                            if (!peer)
                            {
                                // TODO deal with this
                                continue;
                            }
                        }
                    }
                }
                break;

            case 0x04: // player connected
                {
                    if (event.packet->dataLength != 2) break;
                    if (data[1] > 15) break;

                    ConnectedBitmask |= (1<<data[1]);
                }
                break;

            case 0x05: // player disconnected
                {
                    if (event.packet->dataLength != 2) break;
                    if (data[1] > 15) break;

                    ConnectedBitmask &= ~(1<<data[1]);
                }
                break;
            }

            enet_packet_destroy(event.packet);
        }
        break;
    }
}

void ProcessEvent(ENetEvent& event)
{
    if (IsHost)
        ProcessHostEvent(event);
    else
        ProcessClientEvent(event);
}

void Process(bool block)
{
    if (!Host) return;

    int timeout = block ? MPRecvTimeout : 0;
    u32 time_last = SDL_GetTicks();

    ENetEvent event;
    while (enet_host_service(Host, &event, timeout) > 0)
    {
        if (event.type == ENET_EVENT_TYPE_RECEIVE && event.channelID == 1)
        {
            RXQueue.push(event.packet);
            if (block) return;
        }
        else
        {
            ProcessEvent(event);
            if (block)
            {
                u32 time = SDL_GetTicks();
                timeout -= (time - time_last);
                if (timeout <= 0) return;
            }
        }
    }
}


void SetMPRecvTimeout(int timeout)
{
    MPRecvTimeout = timeout;
}

void MPBegin()
{
    ConnectedBitmask |= (1<<MyPlayer.ID);

    u8 cmd[2] = {0x04, MyPlayer.ID};
    ENetPacket* pkt = enet_packet_create(cmd, 2, ENET_PACKET_FLAG_RELIABLE);
    enet_host_broadcast(Host, 0, pkt);
}

void MPEnd()
{
    ConnectedBitmask &= ~(1<<MyPlayer.ID);

    u8 cmd[2] = {0x05, MyPlayer.ID};
    ENetPacket* pkt = enet_packet_create(&cmd, 2, ENET_PACKET_FLAG_RELIABLE);
    enet_host_broadcast(Host, 0, pkt);
}


int SendMPPacketGeneric(u32 type, u8* packet, int len, u64 timestamp)
{
    if (!Host) return 0;

    // TODO make the reliable part optional?
    u32 flags = ENET_PACKET_FLAG_RELIABLE;

    ENetPacket* enetpacket = enet_packet_create(nullptr, sizeof(MPPacketHeader)+len, flags);

    MPPacketHeader pktheader;
    pktheader.Magic = 0x4946494E;
    pktheader.SenderID = MyPlayer.ID;
    pktheader.Type = type;
    pktheader.Length = len;
    pktheader.Timestamp = timestamp;
    memcpy(&enetpacket->data[0], &pktheader, sizeof(MPPacketHeader));
    if (len)
        memcpy(&enetpacket->data[sizeof(MPPacketHeader)], packet, len);

    enet_host_broadcast(Host, 1, enetpacket);
    enet_host_flush(Host);

    return len;
}

int RecvMPPacketGeneric(u8* packet, bool block, u64* timestamp)
{
    if (!Host) return 0;

    Process(block);
    if (RXQueue.empty()) return 0;

    ENetPacket* enetpacket = RXQueue.front();
    RXQueue.pop();
    MPPacketHeader* header = (MPPacketHeader*)&enetpacket->data[0];
    bool good = true;
    if (enetpacket->dataLength < sizeof(MPPacketHeader))
        good = false;
    else if (header->Magic != 0x4946494E)
        good = false;
    else if (header->SenderID == MyPlayer.ID)
        good = false;

    if (!good)
    {
        enet_packet_destroy(enetpacket);
        return 0;
    }

    u32 len = header->Length;
    if (len)
        memcpy(packet, &enetpacket->data[sizeof(MPPacketHeader)], len);

    if (timestamp) *timestamp = header->Timestamp;
    return len;
}


int SendMPPacket(u8* packet, int len, u64 timestamp)
{
    return SendMPPacketGeneric(0, packet, len, timestamp);
}

int RecvMPPacket(u8* packet, u64* timestamp)
{
    return RecvMPPacketGeneric(packet, false, timestamp);
}


int SendMPCmd(u8* packet, int len, u64 timestamp)
{
    return SendMPPacketGeneric(1, packet, len, timestamp);
}

int SendMPReply(u8* packet, int len, u64 timestamp, u16 aid)
{
    return SendMPPacketGeneric(2 | (aid<<16), packet, len, timestamp);
}

int SendMPAck(u8* packet, int len, u64 timestamp)
{
    return SendMPPacketGeneric(3, packet, len, timestamp);
}

int RecvMPHostPacket(u8* packet, u64* timestamp)
{
    return 0;
}

u16 RecvMPReplies(u8* packets, u64 timestamp, u16 aidmask)
{
    return 0;
}

}