#include <sys/types.h>
#include <stdlib.h>
#include <libgte.h>
#include <libgpu.h>
#include <libgs.h>

DRAWENV     draw;           /*Drawing environment*/
DISPENV     disp;               /*Display environment*/

#define OT_LENGTH 1 // the ordertable length
#define PACKETMAX 10000 // the maximum number of objects on the screen (please note that i added more than on the hello word example so it can display all the triangles correctly)

GsOT myOT[2]; // ordering table header
GsOT_TAG myOT_TAG[2][1<<OT_LENGTH]; // ordering table unit
PACKET GPUPacketArea[2][PACKETMAX]; // GPU packet data

unsigned char CurrentBuffer = 0; // holds the current buffer number
unsigned char vertical_spaces = 0; //for the for loop in the Main loop
unsigned short line_y_movement = 0;

//Prototypes
void init_graphics(); // inits the GPU
void animated_line(); // draws a line that moves across the screen vertically
void display(unsigned char r, unsigned char g, unsigned char b); // updates the GPU (IE: VRAM/SGRAM/framebuffer), and clear the screen to the given rgb colors

//Code flow
int main(){ ResetGraph(0);
    FntLoad(960, 256); // load the font from the BIOS into the framebuffer
    SetDumpFnt(FntOpen(0, 0, 640, 512, 0, 1024)); // screen X,Y | max text length X,Y | autmatic background clear 0,1 | max characters
    init_graphics();
    SetDispMask(1);     /*Enable display (0:inhibit, 1:enable)*/
//Main loop
    while(1){
        FntPrint("                       HI, I AM AT THE TOP OF THE SCREEN                        \n\n");
        FntPrint("              HELLO WORLD\n\n          HTTP://PSXDEV.NET/");
        for(vertical_spaces = 0; vertical_spaces < 58; vertical_spaces++){ //this for loop makes enough vertical spaces so the bottom screen text displays in place
        FntPrint("\n");
        }
        FntPrint("                    HELLOO, I AM AT THE BOTTOM OF THE SCREEN                    ");
        animated_line();
        display(128,93,105); //the parameters are the background's color, each one is rgb respectively
    }
    return(0);
}

void init_graphics(){
    GsInitGraph(640, 511, GsINTER|GsOFSGPU, 0, 0); // set the graphics mode resolutions (GsNONINTER for NTSC, and GsINTER for PAL)
    GsDefDispBuff(0, 0, 0, 0); // tell the GPU to draw from the top left coordinates of the framebuffer

    SetVideoMode(1); //Sets video mode to Pal

    SetDefDrawEnv(&draw, 0,  0, 640, 511);
    SetDefDispEnv(&disp, 0,  0, 640, 511);

    /*Enable drawing on display*/
    draw.dfe = 1;

    /*Turn on interlaced mode*/
    disp.isinter = 1;

    /*Moves the display offset so they look centered on pal*/
    disp.screen.y = 16;
    disp.screen.x = -8;
    disp.screen.h = 256;

    /*Set up ordering table*/
    // init the ordertables
    myOT[0].length = OT_LENGTH;
    myOT[1].length = OT_LENGTH;
    myOT[0].org = myOT_TAG[0];
    myOT[1].org = myOT_TAG[1];

    // clear the ordertables
    GsClearOt(0,0,&myOT[0]);
    GsClearOt(0,0,&myOT[1]);
}

LINE_F2 F2Line;
void animated_line(){
    SetLineF2(&F2Line);                                                 // initialise the primitive
    setRGB0(&F2Line, 0, 255, 0);                                        // set the fill colour (RGB)
    setSemiTrans(&F2Line, 1);                                           // semi-transparency; 0=off; 1=on
    setXY2(&F2Line, 0, 0 + line_y_movement, 640, 0 + line_y_movement);  // draw 3 lines (3 sets of x/y co-ords)
    DrawPrim(&F2Line);                                                  // copy shape to frame buffer
    GsSortPoly(&F2Line, &myOT[CurrentBuffer], 0);                       // put the polygon into the order table
    if (line_y_movement < 512) line_y_movement++;                       // if line_y_movement is below 512, increment it by 1 each time
    else line_y_movement = 0;                                           // else if it gets to 512, line_y_movement goes back to 0
}

void display(unsigned char r, unsigned char g, unsigned char b){
    // refresh the font
    FntFlush(-1);

    PutDrawEnv(&draw);
    PutDispEnv(&disp);

    // get the current buffer
    CurrentBuffer = GsGetActiveBuff();

    // setup the packet workbase
    GsSetWorkBase((PACKET*)GPUPacketArea[CurrentBuffer]);

    // clear the ordering table
    GsClearOt(0,0, &myOT[CurrentBuffer]);

    // wait for all drawing to finish
    DrawSync(0);

    // wait for v_blank interrupt
    VSync(0);

    // flip the double buffers
    GsSwapDispBuff();

    // clear the ordering table with a background color (R,G,B)
    GsSortClear(r, g, b, &myOT[CurrentBuffer]);

    // draw the ordering table
    GsDrawOt(&myOT[CurrentBuffer]);
}