/*
*   This file is part of Luma3DS.
*   Copyright (C) 2016-2020 Aurora Wright, TuxSH
*
*   SPDX-License-Identifier: (MIT OR GPL-2.0-or-later)
*/

#include "gdb/server.h"
#include "gdb/net.h"
#include "gdb/query.h"
#include "gdb/verbose.h"
#include "gdb/thread.h"
#include "gdb/debug.h"
#include "gdb/regs.h"
#include "gdb/mem.h"
#include "gdb/hio.h"
#include "gdb/watchpoints.h"
#include "gdb/breakpoints.h"
#include "gdb/stop_point.h"
#include "task_runner.h"

Result GDB_InitializeServer(GDBServer *server)
{
    Result ret = server_init(&server->super);
    if(ret != 0)
        return ret;

    server->super.host = 0;

    server->super.accept_cb = (sock_accept_cb)GDB_AcceptClient;
    server->super.data_cb   = (sock_data_cb)  GDB_DoPacket;
    server->super.close_cb  = (sock_close_cb) GDB_CloseClient;

    server->super.alloc     = (sock_alloc_func)   GDB_GetClient;
    server->super.free      = (sock_free_func)    GDB_ReleaseClient;

    server->super.clients_per_server = 1;

    server->referenceCount = 0;
    svcCreateEvent(&server->statusUpdated, RESET_ONESHOT);
    svcCreateEvent(&server->statusUpdateReceived, RESET_STICKY);

    for(u32 i = 0; i < sizeof(server->ctxs) / sizeof(GDBContext); i++)
        GDB_InitializeContext(server->ctxs + i);

    GDB_ResetWatchpoints();

    return 0;
}

void GDB_FinalizeServer(GDBServer *server)
{
    server_finalize(&server->super);

    // Kill the "next application" context if needed
    for (u32 i = 0; i < MAX_DEBUG; i++) {
        if (server->ctxs[i].debug != 0)
            GDB_CloseClient(&server->ctxs[i]);
    }
    svcCloseHandle(server->statusUpdated);
    svcCloseHandle(server->statusUpdateReceived);
}

void GDB_IncrementServerReferenceCount(GDBServer *server)
{
    AtomicPostIncrement(&server->referenceCount);
}

void GDB_DecrementServerReferenceCount(GDBServer *server)
{
    if(AtomicDecrement(&server->referenceCount) == 0)
        GDB_FinalizeServer(server);
}

void GDB_RunServer(GDBServer *server)
{
    Result res = server_bind(&server->super, GDB_PORT_BASE);
    if(R_SUCCEEDED(res)) res = server_bind(&server->super, GDB_PORT_BASE + 1);
    if(R_SUCCEEDED(res)) res = server_bind(&server->super, GDB_PORT_BASE + 2);

    if(R_SUCCEEDED(res)) res = server_bind(&server->super, GDB_PORT_BASE + 3); // next application

    if(R_SUCCEEDED(res))
        server_run(&server->super);
}

void GDB_LockAllContexts(GDBServer *server)
{
    for (u32 i = 0; i < MAX_DEBUG; i++)
        RecursiveLock_Lock(&server->ctxs[i].lock);
}

void GDB_UnlockAllContexts(GDBServer *server)
{
    for (u32 i = MAX_DEBUG; i > 0; i--)
        RecursiveLock_Unlock(&server->ctxs[i - 1].lock);
}

GDBContext *GDB_SelectAvailableContext(GDBServer *server, u16 minPort, u16 maxPort)
{
    GDBContext *ctx;
    u16 port;

    GDB_LockAllContexts(server);

    // Get a context
    u32 id;
    for(id = 0; id < MAX_DEBUG && (server->ctxs[id].flags & GDB_FLAG_ALLOCATED_MASK); id++);
    if(id < MAX_DEBUG)
        ctx = &server->ctxs[id];
    else
    {
        GDB_UnlockAllContexts(server);
        return NULL;
    }

    // Get a port
    for (port = minPort; port < maxPort; port++)
    {
        bool portUsed = false;
        for(id = 0; id < MAX_DEBUG; id++)
        {
            if((server->ctxs[id].flags & GDB_FLAG_ALLOCATED_MASK) && server->ctxs[id].localPort == port)
                portUsed = true;
        }

        if (!portUsed)
            break;
    }

    if (port >= maxPort)
    {
        ctx->flags = ~GDB_FLAG_SELECTED;
        ctx = NULL;
    }
    else
    {
        ctx->flags |= GDB_FLAG_SELECTED;
        ctx->localPort = port;
        ctx->parent = server;
    }

    GDB_UnlockAllContexts(server);
    return ctx;
}

GDBContext *GDB_FindAllocatedContextByPid(GDBServer *server, u32 pid)
{
    GDB_LockAllContexts(server);
    GDBContext *ctx = NULL;
    for(u32 i = 0; i < MAX_DEBUG; i++)
    {
        if(
            ((server->ctxs[i].flags & GDB_FLAG_SELECTED) ||
                (server->ctxs[i].state >= GDB_STATE_ATTACHED && server->ctxs[i].state < GDB_STATE_DETACHING))
            && server->ctxs[i].pid == pid
        )
            ctx = &server->ctxs[i];
    }
    GDB_UnlockAllContexts(server);
    return ctx;
}

int GDB_AcceptClient(GDBContext *ctx)
{
    Result r = 0;

    RecursiveLock_Lock(&ctx->lock);
    ctx->state = GDB_STATE_CONNECTED;
    ctx->latestSentPacketSize = 0;

    if (ctx->flags & GDB_FLAG_SELECTED)
        r = GDB_AttachToProcess(ctx);

    RecursiveLock_Unlock(&ctx->lock);

    return R_SUCCEEDED(r) ? 0 : -1;
}

int GDB_CloseClient(GDBContext *ctx)
{
    RecursiveLock_Lock(&ctx->lock);
    svcClearEvent(ctx->processAttachedEvent);
    ctx->eventToWaitFor = ctx->processAttachedEvent;
    svcClearEvent(ctx->parent->statusUpdateReceived);
    svcSignalEvent(ctx->parent->statusUpdated); // note: monitor will be waiting for lock
    RecursiveLock_Unlock(&ctx->lock);

    if(ctx->parent->referenceCount >= 2)
        svcWaitSynchronization(ctx->parent->statusUpdateReceived, -1LL);

    RecursiveLock_Lock(&ctx->lock);
    if (ctx->state >= GDB_STATE_ATTACHED || ctx->debug != 0)
        GDB_DetachFromProcess(ctx);

    ctx->localPort = 0;
    ctx->enableExternalMemoryAccess = false;
    ctx->flags = 0;
    ctx->state = GDB_STATE_DISCONNECTED;

    ctx->catchThreadEvents = false;

    memset(&ctx->latestDebugEvent, 0, sizeof(DebugEventInfo));
    memset(ctx->memoryOsInfoXmlData, 0, sizeof(ctx->memoryOsInfoXmlData));
    memset(ctx->processesOsInfoXmlData, 0, sizeof(ctx->processesOsInfoXmlData));

    for (u32 i = 0; i < MAX_TIO_OPEN_FILE; i++)
        IFile_Close(&ctx->openTioFileInfos[i].f);
    memset(ctx->openTioFileInfos, 0, sizeof(ctx->openTioFileInfos));
    ctx->numOpenTioFiles = 0;

    RecursiveLock_Unlock(&ctx->lock);
    return 0;
}

GDBContext *GDB_GetClient(GDBServer *server, u16 port)
{
    GDB_LockAllContexts(server);
    GDBContext *ctx = NULL;
    for (u32 i = 0; i < MAX_DEBUG; i++)
    {
        if (server->ctxs[i].localPort == port)
        {
            ctx = &server->ctxs[i];
            break;
        }
    }

    if (ctx != NULL)
    {
        // Context already tied to a port/selected
        if (ctx->flags & GDB_FLAG_USED)
        {
            GDB_UnlockAllContexts(server);
            return NULL;
        }

        ctx->flags |= GDB_FLAG_USED;
        ctx->state = GDB_STATE_CONNECTED;
        ctx->parent = server;
    }
    else if (port >= GDB_PORT_BASE && port < GDB_PORT_BASE + MAX_DEBUG)
    {
        // Grab a free context
        u32 id;
        for(id = 0; id < MAX_DEBUG && (server->ctxs[id].flags & GDB_FLAG_ALLOCATED_MASK); id++);
        if(id < MAX_DEBUG)
            ctx = &server->ctxs[id];
        else
        {
            GDB_UnlockAllContexts(server);
            return NULL;
        }

        ctx->localPort = port;
        ctx->flags |= GDB_FLAG_USED;
        ctx->state = GDB_STATE_CONNECTED;
        ctx->parent = server;
    }

    GDB_UnlockAllContexts(server);
    if (port == GDB_PORT_BASE + MAX_DEBUG && ctx != NULL)
    {
        // this is not sufficient/foolproof and is buggy: TaskRunner_WaitReady(); // Finish grabbing new process debug, if anything...
        bool ok = false;
        do
        {
            svcSleepThread(5 * 1000 * 1000LL);
            RecursiveLock_Lock(&ctx->lock);
            ok = ctx->debug != 0;
            RecursiveLock_Unlock(&ctx->lock);
        }
        while (!ok);
    }

    return ctx;
}

void GDB_ReleaseClient(GDBServer *server, GDBContext *ctx)
{
    (void)server;
    (void)ctx;
}

static const struct
{
    char command;
    GDBCommandHandler handler;
} gdbCommandHandlers[] =
{
    { '?', GDB_HANDLER(GetStopReason) },
    { '!', GDB_HANDLER(EnableExtendedMode) },
    { 'c', GDB_HANDLER(Continue) },
    { 'C', GDB_HANDLER(Continue) },
    { 'D', GDB_HANDLER(Detach) },
    { 'F', GDB_HANDLER(HioReply) },
    { 'g', GDB_HANDLER(ReadRegisters) },
    { 'G', GDB_HANDLER(WriteRegisters) },
    { 'H', GDB_HANDLER(SetThreadId) },
    { 'k', GDB_HANDLER(Kill) },
    { 'm', GDB_HANDLER(ReadMemory) },
    { 'M', GDB_HANDLER(WriteMemory) },
    { 'p', GDB_HANDLER(ReadRegister) },
    { 'P', GDB_HANDLER(WriteRegister) },
    { 'q', GDB_HANDLER(ReadQuery) },
    { 'Q', GDB_HANDLER(WriteQuery) },
    { 'R', GDB_HANDLER(Restart) },
    { 'T', GDB_HANDLER(IsThreadAlive) },
    { 'v', GDB_HANDLER(VerboseCommand) },
    { 'X', GDB_HANDLER(WriteMemoryRaw) },
    { 'z', GDB_HANDLER(ToggleStopPoint) },
    { 'Z', GDB_HANDLER(ToggleStopPoint) },
};

static inline GDBCommandHandler GDB_GetCommandHandler(char command)
{
    static const u32 nbHandlers = sizeof(gdbCommandHandlers) / sizeof(gdbCommandHandlers[0]);

    u32 i;
    for(i = 0; i < nbHandlers && gdbCommandHandlers[i].command != command; i++);

    return i < nbHandlers ? gdbCommandHandlers[i].handler : GDB_HANDLER(Unsupported);
}

int GDB_DoPacket(GDBContext *ctx)
{
    int ret;

    RecursiveLock_Lock(&ctx->lock);
    u32 oldFlags = ctx->flags;

    if(ctx->state == GDB_STATE_DISCONNECTED)
        return -1;

    int r = GDB_ReceivePacket(ctx);
    if(r == 0)
        ret = 0;
    else if(r == -1)
        ret = -1;
    else if(ctx->buffer[0] == '\x03')
    {
        GDB_HandleBreak(ctx);
        ret = 0;
    }
    else if(ctx->buffer[0] == '$')
    {
        GDBCommandHandler handler = GDB_GetCommandHandler(ctx->buffer[1]);
        ctx->commandData = ctx->buffer + 2;
        ret = handler(ctx);
    }
    else
        ret = 0;

    if(ctx->state == GDB_STATE_DETACHING)
    {
        if(ctx->flags & GDB_FLAG_EXTENDED_REMOTE)
        {
            ctx->state = GDB_STATE_CONNECTED;
            RecursiveLock_Unlock(&ctx->lock);
            return ret;
        }
        else
        {
            RecursiveLock_Unlock(&ctx->lock);
            return -1;
        }
    }

    if((oldFlags & GDB_FLAG_PROCESS_CONTINUING) && !(ctx->flags & GDB_FLAG_PROCESS_CONTINUING))
    {
        if(R_FAILED(svcBreakDebugProcess(ctx->debug)))
            ctx->flags |= GDB_FLAG_PROCESS_CONTINUING;
    }
    else if(!(oldFlags & GDB_FLAG_PROCESS_CONTINUING) && (ctx->flags & GDB_FLAG_PROCESS_CONTINUING))
        svcSignalEvent(ctx->continuedEvent);

    RecursiveLock_Unlock(&ctx->lock);
    return ret;
}