/*
https://github.com/peterix/dfhack
Copyright (c) 2009-2012 Petr Mrázek (peterix@gmail.com)

This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any
damages arising from the use of this software.

Permission is granted to anyone to use this software for any
purpose, including commercial applications, and to alter it and
redistribute it freely, subject to the following restrictions:

1. The origin of this software must not be misrepresented; you must
not claim that you wrote the original software. If you use this
software in a product, an acknowledgment in the product documentation
would be appreciated but is not required.

2. Altered source versions must be plainly marked as such, and
must not be misrepresented as being the original software.

3. This notice may not be removed or altered from any source
distribution.
*/


#include <stdio.h>
#include <dlfcn.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <sys/shm.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <vector>
#include <string>
#include <map>

typedef struct interpose_s
{
  void *new_func;
  void *orig_func;
} interpose_t;

#include "DFHack.h"
#include "Core.h"
#include "Hooks.h"
#include "SDL_events.h"
#include <iostream>

/*static const interpose_t interposers[] __attribute__ ((section("__DATA, __interpose"))) =
{
     { (void *)DFH_SDL_Init,  (void *)SDL_Init  },
     { (void *)DFH_SDL_PollEvent, (void *)SDL_PollEvent },
     { (void *)DFH_SDL_Quit, (void *)SDL_Quit },
     { (void *)DFH_SDL_NumJoysticks, (void *)SDL_NumJoysticks },

};*/

#define DYLD_INTERPOSE(_replacement,_replacee) \
    __attribute__((used)) static struct{ const void* replacment; const void* replacee; } \
    _interpose_##_replacee __attribute__ ((section ("__DATA,__interpose"))) = \
    { (const void*)(unsigned long)&_replacement, (const void*)(unsigned long)&_replacee };

DYLD_INTERPOSE(DFH_SDL_Init,SDL_Init);
DYLD_INTERPOSE(DFH_SDL_PollEvent,SDL_PollEvent);
DYLD_INTERPOSE(DFH_SDL_Quit,SDL_Quit);
DYLD_INTERPOSE(DFH_SDL_NumJoysticks,SDL_NumJoysticks);
DYLD_INTERPOSE(DFH_wgetch,wgetch);

/*******************************************************************************
*                           SDL part starts here                               *
*******************************************************************************/

#define SDL_APPMOUSEFOCUS       0x01            /**< The app has mouse coverage */
#define SDL_APPINPUTFOCUS       0x02            /**< The app has input focus */
#define SDL_APPACTIVE           0x04            /**< The application is active */
static uint8_t (*_SDL_GetAppState)(void) = 0;
DFhackCExport uint8_t SDL_GetAppState(void)
{
    return _SDL_GetAppState();
}

// hook - called for each game tick (or more often)
DFhackCExport int DFH_SDL_NumJoysticks(void)
{
    DFHack::Core & c = DFHack::Core::getInstance();
    return c.Update();
}

// hook - called at program exit
static void (*_SDL_Quit)(void) = 0;
DFhackCExport void DFH_SDL_Quit(void)
{
    DFHack::Core & c = DFHack::Core::getInstance();
    c.Shutdown();

    SDL_Quit();
}

// called by DF to check input events
static int (*_SDL_PollEvent)(SDL::Event* event) = 0;
DFhackCExport int DFH_SDL_PollEvent(SDL::Event* event)
{
    pollevent_again:
    // if SDL returns 0 here, it means there are no more events. return 0
    int orig_return = SDL_PollEvent(event);
    if(!orig_return || (!(SDL_GetAppState() & SDL_APPINPUTFOCUS) &&
            (event->type == SDL::ET_KEYDOWN || event->type == SDL::ET_KEYUP)))
        return 0;
    // otherwise we have an event to filter
    else if( event != 0 )
    {
        DFHack::Core & c = DFHack::Core::getInstance();
        // if we consume the event, ask SDL for more.
        if(!c.DFH_SDL_Event(event))
            goto pollevent_again;
    }
    return orig_return;
}

static int (*_SDL_PushEvent)(SDL::Event* event) = 0;
DFhackCExport int SDL_PushEvent(SDL::Event* event)
{
    return _SDL_PushEvent(event);
}

struct WINDOW;
DFhackCExport int DFH_wgetch(WINDOW *win)
{
    DFHack::Core & c = DFHack::Core::getInstance();
    wgetch_again:
    int in = wgetch(win);
    int out;
    if(c.ncurses_wgetch(in, out))
    {
        // not consumed, give to DF
        return out;
    }
    else
    {
        // consumed, repeat
        goto wgetch_again;
    }
}

void dlsym_bind_or_exit(void **target, const char *name)
{
    void *sym = dlsym(RTLD_NEXT, name);
    if (sym)
    {
        if (*target && *target != sym)
        {
            fprintf(stderr, "warning: rebinding symbol %s from %p to %p\n",
                name, *target, sym);
        }
        *target = sym;
    }
    else
    {
        fprintf(stderr, "Fatal: Could not find symbol: %s\n", name);
        fprintf(stdout, "dfhack: something went horribly wrong\n"
            "Check stderr.log for details\n");
        exit(1);
    }
}


// New SDL functions starting in r5
static vPtr (*_SDL_CreateRGBSurface)(uint32_t flags, int width, int height, int depth,
                                     uint32_t Rmask, uint32_t Gmask, uint32_t Bmask, uint32_t Amask) = 0;
DFhackCExport vPtr SDL_CreateRGBSurface(uint32_t flags, int width, int height, int depth,
                                     uint32_t Rmask, uint32_t Gmask, uint32_t Bmask, uint32_t Amask)
{
    return _SDL_CreateRGBSurface(flags, width, height, depth, Rmask, Gmask, Bmask, Amask);
}

static vPtr (*_SDL_CreateRGBSurfaceFrom)(vPtr pixels, int width, int height, int depth, int pitch,
                                         uint32_t Rmask, uint32_t Gmask, uint32_t Bmask, uint32_t Amask) = 0;
DFhackCExport vPtr SDL_CreateRGBSurfaceFrom(vPtr pixels, int width, int height, int depth, int pitch,
                                         uint32_t Rmask, uint32_t Gmask, uint32_t Bmask, uint32_t Amask)
{
    return _SDL_CreateRGBSurfaceFrom(pixels, width, height, depth, pitch, Rmask, Gmask, Bmask, Amask);
}

static void (*_SDL_FreeSurface)(vPtr surface) = 0;
DFhackCExport void SDL_FreeSurface(vPtr surface)
{
    _SDL_FreeSurface(surface);
}

static vPtr (*_SDL_ConvertSurface)(vPtr surface, vPtr format, uint32_t flags) = 0;
DFhackCExport vPtr SDL_ConvertSurface(vPtr surface, vPtr format, uint32_t flags)
{
    return _SDL_ConvertSurface(surface, format, flags);
}

static int (*_SDL_LockSurface)(vPtr surface) = 0;
DFhackCExport int SDL_LockSurface(vPtr surface)
{
    return _SDL_LockSurface(surface);
}

static void (*_SDL_UnlockSurface)(vPtr surface) = 0;
DFhackCExport void SDL_UnlockSurface(vPtr surface)
{
    _SDL_UnlockSurface(surface);
}

static uint8_t (*_SDL_GetMouseState)(int *, int *) = 0;
DFhackCExport uint8_t SDL_GetMouseState(int *x, int *y)
{
    return _SDL_GetMouseState(x,y);
}

static void * (*_SDL_GetVideoSurface)( void ) = 0;
DFhackCExport void * SDL_GetVideoSurface(void)
{
    return _SDL_GetVideoSurface();
}

static int (*_SDL_UpperBlit)(DFHack::DFSDL_Surface* src, DFHack::DFSDL_Rect* srcrect, DFHack::DFSDL_Surface* dst, DFHack::DFSDL_Rect* dstrect) = 0;
DFhackCExport int SDL_UpperBlit(DFHack::DFSDL_Surface* src, DFHack::DFSDL_Rect* srcrect, DFHack::DFSDL_Surface* dst, DFHack::DFSDL_Rect* dstrect)
{
    DFHack::Core & c = DFHack::Core::getInstance();
    if ( c.isValid() && dstrect != NULL && dstrect->h != 0 && dstrect->w != 0 )
    {
        DFHack::Graphic* g = c.getGraphic();
        DFHack::DFTileSurface* ov = g->Call(dstrect->x/dstrect->w, dstrect->y/dstrect->h);

        if ( ov != NULL )
        {
            if ( ov->paintOver )
            {
                _SDL_UpperBlit(src, srcrect, dst, dstrect);
            }

            DFHack::DFSDL_Rect* dstrect2 = new DFHack::DFSDL_Rect;
            dstrect2->x = dstrect->x;
            dstrect2->y = dstrect->y;
            dstrect2->w = dstrect->w;
            dstrect2->h = dstrect->h;

            if ( ov->dstResize != NULL )
            {
                DFHack::DFSDL_Rect* r = (DFHack::DFSDL_Rect*)ov->dstResize;
                dstrect2->x += r->x;
                dstrect2->y += r->y;
                dstrect2->w += r->w;
                dstrect2->h += r->h;
            }

            int result = _SDL_UpperBlit(ov->surface, ov->rect, dst, dstrect2);
            delete dstrect2;
            return result;
        }
    }

    return _SDL_UpperBlit(src, srcrect, dst, dstrect);
}

static int (*_SDL_SemWait)(vPtr) = 0;
DFhackCExport int SDL_SemWait(vPtr sem)
{
    return _SDL_SemWait(sem);
}

static int (*_SDL_SemPost)(vPtr) = 0;
DFhackCExport int SDL_SemPost(vPtr sem)
{
    return _SDL_SemPost(sem);
}

// hook - called at program start, initialize some stuffs we'll use later
static int (*_SDL_Init)(uint32_t flags) = 0;
DFhackCExport int DFH_SDL_Init(uint32_t flags)
{
    // reroute stderr
    fprintf(stderr,"dfhack: attempting to hook in\n");
    freopen("stderr.log", "w", stderr);
    // we don't reroute stdout until  we figure out if this should be done at all
    // See: Console-linux.cpp

    // find real functions
    fprintf(stderr,"dfhack: saving real SDL functions\n");

    #define bind(sym) dlsym_bind_or_exit((void**)&_##sym, #sym)
    bind(SDL_Init);
    bind(SDL_Quit);
    bind(SDL_PollEvent);
    bind(SDL_PushEvent);

    bind(SDL_UpperBlit);
    bind(SDL_CreateRGBSurface);
    bind(SDL_CreateRGBSurfaceFrom);
    bind(SDL_FreeSurface);
    bind(SDL_ConvertSurface);
    bind(SDL_LockSurface);
    bind(SDL_UnlockSurface);
    bind(SDL_GetMouseState);
    bind(SDL_GetVideoSurface);

    bind(SDL_SemWait);
    bind(SDL_SemPost);
    bind(SDL_GetAppState);
    #undef bind

    fprintf(stderr, "dfhack: saved real SDL functions\n");
    assert(_SDL_Init && _SDL_Quit && _SDL_PollEvent);
    fprintf(stderr, "dfhack: hooking successful\n");

    // prevent any subprocesses from trying to load libdfhack.dylib
    setenv("DYLD_INSERT_LIBRARIES", "", 1);

    int ret = SDL_Init(flags);
    return ret;
}