typedef unsigned char uint8_t;
typedef signed char int8_t;
typedef unsigned short uint16_t;
typedef unsigned int uint32_t;
typedef unsigned long long uint64_t;

struct multiboot_info {
    uint32_t flags; uint32_t mem_lower; uint32_t mem_upper; uint32_t boot_device;
    uint32_t cmdline; uint32_t mods_count; uint32_t mods_addr; uint32_t syms[4];
    uint32_t mmap_length; uint32_t mmap_addr; uint32_t drives_length; uint32_t drives_addr;
    uint32_t config_table; uint32_t boot_loader_name; uint32_t apm_table;
    uint32_t vbe_control_info; uint32_t vbe_mode_info; uint16_t vbe_mode;
    uint16_t vbe_interface_seg; uint16_t vbe_interface_off; uint16_t vbe_interface_len;
    uint64_t framebuffer_addr; uint32_t framebuffer_pitch; uint32_t framebuffer_width;
    uint32_t framebuffer_height; uint8_t framebuffer_bpp; uint8_t framebuffer_type;
} __attribute__((packed));

uint8_t inb(uint16_t p) { uint8_t r; __asm__("in %%dx, %%al":"=a"(r):"d"(p)); return r; }
void outb(uint16_t p, uint8_t d) { __asm__("out %%al, %%dx"::"a"(d),"d"(p)); }

uint32_t* vram = 0;
int scr_w=0, scr_h=0, pitch=0;
int mx=400, my=300;
uint32_t mouse_bg[100]; // Save buffer for mouse
uint8_t mouse_cycle = 0;
int8_t mouse_byte[3];
uint8_t mouse_btn_left = 0;

struct Window {
    int x, y, w, h;
    int dragging;
    int resizing;
    int drag_off_x, drag_off_y;
};
struct Window win = {100, 100, 400, 300, 0, 0, 0, 0};

uint8_t font8x8[96][8] = {
    {0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00}, // Space
    {0x18,0x3C,0x3C,0x18,0x18,0x00,0x18,0x00}, // !
    {0x66,0x66,0x22,0x00,0x00,0x00,0x00,0x00}, // "
    {0x6C,0x6C,0xFE,0x6C,0xFE,0x6C,0x6C,0x00}, // #
    {0x18,0x7E,0xC0,0x3C,0x06,0x7E,0x18,0x00}, // $
    {0x00,0xC6,0xCC,0x18,0x30,0x66,0xC6,0x00}, // %
    {0x38,0x6C,0x38,0x76,0xDC,0xCC,0x76,0x00}, // &
    {0x18,0x18,0x30,0x00,0x00,0x00,0x00,0x00}, // '
    {0x0C,0x18,0x30,0x30,0x30,0x18,0x0C,0x00}, // (
    {0x30,0x18,0x0C,0x0C,0x0C,0x18,0x30,0x00}, // )
    {0x00,0x66,0x3C,0xFF,0x3C,0x66,0x00,0x00}, // *
    {0x00,0x18,0x18,0x7E,0x18,0x18,0x00,0x00}, // +
    {0x00,0x00,0x00,0x00,0x00,0x18,0x18,0x30}, // ,
    {0x00,0x00,0x00,0x7E,0x00,0x00,0x00,0x00}, // -
    {0x00,0x00,0x00,0x00,0x00,0x18,0x18,0x00}, // .
    {0x00,0x06,0x0C,0x18,0x30,0x60,0xC0,0x00}, // /
    {0x3C,0x66,0x66,0x66,0x66,0x66,0x3C,0x00}, // 0
    {0x18,0x38,0x18,0x18,0x18,0x18,0x7E,0x00}, // 1
    {0x3C,0x66,0x06,0x0C,0x30,0x60,0x7E,0x00}, // 2
    {0x3C,0x66,0x06,0x1C,0x06,0x66,0x3C,0x00}, // 3
    {0x0C,0x1C,0x3C,0x6C,0xCC,0xFE,0x0C,0x00}, // 4
    {0x7E,0xC0,0xFC,0x06,0x06,0x66,0x3C,0x00}, // 5
    {0x3C,0x60,0xC0,0xFC,0x66,0x66,0x3C,0x00}, // 6
    {0x7E,0x06,0x0C,0x18,0x30,0x30,0x30,0x00}, // 7
    {0x3C,0x66,0x66,0x3C,0x66,0x66,0x3C,0x00}, // 8
    {0x3C,0x66,0x66,0x3E,0x06,0x06,0x3C,0x00}, // 9
    {0x00,0x18,0x18,0x00,0x00,0x18,0x18,0x00}, // :
    {0x00,0x18,0x18,0x00,0x00,0x18,0x18,0x30}, // ;
    {0x06,0x0C,0x18,0x30,0x18,0x0C,0x06,0x00}, // <
    {0x00,0x00,0x7E,0x00,0x00,0x7E,0x00,0x00}, // =
    {0x60,0x30,0x18,0x0C,0x18,0x30,0x60,0x00}, // >
    {0x3C,0x66,0x06,0x0C,0x18,0x00,0x18,0x00}, // ?
    {0x3C,0x66,0x6E,0x6E,0x60,0x62,0x3C,0x00}, // @
    {0x18,0x3C,0x66,0x66,0x7E,0x66,0x66,0x00}, // A
    {0x7C,0x66,0x66,0x7C,0x66,0x66,0x7C,0x00}, // B
    {0x3C,0x66,0x60,0x60,0x60,0x66,0x3C,0x00}, // C
    {0x78,0x6C,0x66,0x66,0x66,0x6C,0x78,0x00}, // D
    {0x7E,0x60,0x60,0x78,0x60,0x60,0x7E,0x00}, // E
    {0x7E,0x60,0x60,0x78,0x60,0x60,0x60,0x00}, // F
    {0x3C,0x66,0x60,0x6E,0x66,0x66,0x3C,0x00}, // G
    {0x66,0x66,0x66,0x7E,0x66,0x66,0x66,0x00}, // H
    {0x3C,0x18,0x18,0x18,0x18,0x18,0x3C,0x00}, // I
    {0x1E,0x0C,0x0C,0x0C,0xCC,0xCC,0x78,0x00}, // J
    {0xE6,0x66,0x6C,0x78,0x6C,0x66,0xE6,0x00}, // K
    {0xF0,0x60,0x60,0x60,0x62,0x66,0xFE,0x00}, // L
    {0xC6,0xEE,0xFE,0xD6,0xC6,0xC6,0xC6,0x00}, // M
    {0xC6,0xE6,0xF6,0xDE,0xCE,0xC6,0xC6,0x00}, // N
    {0x3C,0x66,0x66,0x66,0x66,0x66,0x3C,0x00}, // O
    {0xFC,0x66,0x66,0x7C,0x60,0x60,0xF0,0x00}, // P
    {0x7C,0xC6,0xC6,0xC6,0xD6,0x7C,0x0E,0x00}, // Q
    {0xFC,0x66,0x66,0x7C,0x6C,0x66,0xE6,0x00}, // R
    {0x3C,0x66,0x30,0x18,0x0C,0x66,0x3C,0x00}, // S
    {0x7E,0x18,0x18,0x18,0x18,0x18,0x18,0x00}, // T
    {0xCC,0xCC,0xCC,0xCC,0xCC,0xCC,0x78,0x00}, // U
    {0xCC,0xCC,0xCC,0xCC,0xCC,0x78,0x30,0x00}, // V
    {0xC6,0xC6,0xC6,0xD6,0xFE,0xEE,0xC6,0x00}, // W
    {0xC6,0xC6,0x6C,0x38,0x38,0x6C,0xC6,0x00}, // X
    {0xCC,0xCC,0xCC,0x78,0x30,0x30,0x78,0x00}, // Y
    {0xFE,0x06,0x0C,0x18,0x30,0x60,0xFE,0x00}, // Z
    {0x3C,0x30,0x30,0x30,0x30,0x30,0x3C,0x00}, // [
    {0xC0,0x60,0x30,0x18,0x0C,0x06,0x03,0x00}, // Backslash
    {0x3C,0x0C,0x0C,0x0C,0x0C,0x0C,0x3C,0x00}, // ]
    {0x10,0x38,0x7C,0xFE,0x00,0x00,0x00,0x00}, // ^
    {0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xFF}, // _
    {0x30,0x18,0x0C,0x00,0x00,0x00,0x00,0x00}, // `
    {0x00,0x00,0x78,0x0C,0x7C,0xCC,0x76,0x00}, // a
    {0xE0,0x60,0x60,0x7C,0x66,0x66,0x7C,0x00}, // b
    {0x00,0x00,0x3C,0x60,0x60,0x60,0x3C,0x00}, // c
    {0x1C,0x0C,0x0C,0x7C,0xCC,0xCC,0x76,0x00}, // d
    {0x00,0x00,0x3C,0x66,0x7E,0x60,0x3C,0x00}, // e
    {0x1C,0x36,0x30,0x78,0x30,0x30,0x78,0x00}, // f
    {0x00,0x00,0x3B,0x66,0x66,0x3E,0x06,0x7C}, // g
    {0xE0,0x60,0x60,0x6C,0x66,0x66,0xE6,0x00}, // h
    {0x18,0x00,0x38,0x18,0x18,0x18,0x3C,0x00}, // i
    {0x06,0x00,0x06,0x06,0x06,0x66,0x66,0x3C}, // j
    {0xE0,0x60,0x66,0x6C,0x78,0x6C,0xE6,0x00}, // k
    {0x38,0x18,0x18,0x18,0x18,0x18,0x3C,0x00}, // l
    {0x00,0x00,0xEC,0xFE,0xD6,0xD6,0xC6,0x00}, // m
    {0x00,0x00,0xDC,0x66,0x66,0x66,0x66,0x00}, // n
    {0x00,0x00,0x3C,0x66,0x66,0x66,0x3C,0x00}, // o
    {0x00,0x00,0xDC,0x66,0x66,0x7C,0x60,0xF0}, // p
    {0x00,0x00,0x76,0xCC,0xCC,0x7C,0x0C,0x1E}, // q
    {0x00,0x00,0xDC,0x66,0x60,0x60,0xF0,0x00}, // r
    {0x00,0x00,0x3E,0x60,0x3C,0x06,0x7C,0x00}, // s
    {0x30,0x30,0x7C,0x30,0x30,0x36,0x1C,0x00}, // t
    {0x00,0x00,0xCC,0xCC,0xCC,0xCC,0x76,0x00}, // u
    {0x00,0x00,0xCC,0xCC,0xCC,0x78,0x30,0x00}, // v
    {0x00,0x00,0xC6,0xD6,0xFE,0xEE,0xC6,0x00}, // w
    {0x00,0x00,0xC6,0x6C,0x38,0x6C,0xC6,0x00}, // x
    {0x00,0x00,0xCC,0xCC,0xCC,0x7C,0x0C,0xF8}, // y
    {0x00,0x00,0xFC,0x98,0x30,0x64,0xFC,0x00}, // z
    {0x1C,0x30,0x30,0xE0,0x30,0x30,0x1C,0x00}, // {
    {0x18,0x18,0x18,0x00,0x18,0x18,0x18,0x00}, // |
    {0xE0,0x30,0x30,0x1C,0x30,0x30,0xE0,0x00}, // }
    {0x76,0xDC,0x00,0x00,0x00,0x00,0x00,0x00}  // ~
};

void put_pixel(int x, int y, uint32_t color) {
    if(x>=0 && x<scr_w && y>=0 && y<scr_h) vram[y*(pitch/4)+x] = color;
}
uint32_t get_pixel(int x, int y) {
    if(x>=0 && x<scr_w && y>=0 && y<scr_h) return vram[y*(pitch/4)+x];
    return 0;
}
void draw_rect(int x, int y, int w, int h, uint32_t c) {
    for(int j=y; j<y+h; j++) for(int i=x; i<x+w; i++) put_pixel(i, j, c);
}
void draw_char(int x, int y, char c, uint32_t fg, uint32_t bg) {
    int idx = c - 32; if(idx<0 || idx>95) idx=0;
    for(int r=0; r<8; r++) {
        for(int col=0; col<8; col++) {
            if((font8x8[idx][r] >> (7-col)) & 1) put_pixel(x+col, y+r, fg);
            else if(bg != 0xFFFFFFFF) put_pixel(x+col, y+r, bg);
        }
    }
}
void draw_text(int x, int y, char* s, uint32_t fg, uint32_t bg) {
    while(*s) { draw_char(x, y, *s, fg, bg); x+=8; s++; }
}

char term_buf[64];
int term_idx = 0;
char history[4][64]; 
char* prompt = "root@tiwut:~$ ";

void str_cpy(char* d, char* s) { int i=0; while(s[i] && i<63) { d[i]=s[i]; i++; } d[i]=0; }
void clear_buffer() { for(int i=0;i<64;i++) term_buf[i]=0; term_idx=0; }

void refresh_term() {
    int tx = win.x + 5;
    int ty = win.y + 30;
    
    if(win.w < 20 || win.h < 50) return;
    
    draw_rect(tx, ty, win.w - 10, win.h - 40, 0); 
    
    for(int i=0; i<4; i++) draw_text(tx + 5, ty + 5 +(i*10), history[i], 0xAAAAAA, 0);

    int py = ty + 50;
    draw_text(tx + 5, py, prompt, 0x00FF00, 0);
    draw_text(tx + 5 + (14*8), py, term_buf, 0xFFFFFF, 0);
    draw_char(tx + 5 + (14*8) + (term_idx*8), py, '_', 0xFFFFFF, 0);
}

void add_history(char* msg) {
    str_cpy(history[0], history[1]);
    str_cpy(history[1], history[2]);
    str_cpy(history[2], history[3]);
    str_cpy(history[3], msg);
}

void draw_window() {
    draw_rect(win.x, win.y, win.w, win.h, 0xFFFFFF);
    
    draw_rect(win.x, win.y, win.w, 25, 0x000080);
    draw_text(win.x + 5, win.y + 8, "Terminal", 0xFFFFFF, 0x000080);

    draw_rect(win.x + win.w - 15, win.y + win.h - 15, 15, 15, 0xFF0000);
    
    refresh_term();
}

void redraw_scene() {
    draw_rect(0, 0, 800, 600, 0x003A6EA5);
    draw_rect(0, 560, 800, 40, 0xC0C0C0);
    draw_rect(5, 565, 60, 30, 0x008000);

    draw_window();
}

void mouse_save() {
    for(int y=0;y<10;y++) for(int x=0;x<10;x++) mouse_bg[y*10+x] = get_pixel(mx+x, my+y);
}
void mouse_restore() {
    for(int y=0;y<10;y++) for(int x=0;x<10;x++) put_pixel(mx+x, my+y, mouse_bg[y*10+x]);
}
void mouse_draw() {
    for(int y=0;y<10;y++) for(int x=0;x<10;x++) {
        if(x==0||y==0||x==9||y==9||x==y) put_pixel(mx+x, my+y, 0); 
        else put_pixel(mx+x, my+y, 0xFFFFFF); 
    }
}
void init_mouse_hw() {
    uint32_t t=10000;
    while(t--) if((inb(0x64)&2)==0) break; outb(0x64, 0xA8);
    while(t--) if((inb(0x64)&2)==0) break; outb(0x64, 0x20);
    while(t--) if((inb(0x64)&1)==1) break; uint8_t s=(inb(0x60)|2);
    while(t--) if((inb(0x64)&2)==0) break; outb(0x64, 0x60);
    while(t--) if((inb(0x64)&2)==0) break; outb(0x60, s);
    outb(0x64, 0xD4); outb(0x60, 0xF4); inb(0x60);
}

void kernel_main(uint32_t magic, struct multiboot_info* mb) {
    if(mb->framebuffer_addr == 0) return;
    vram = (uint32_t*)(uint32_t)mb->framebuffer_addr;
    scr_w = mb->framebuffer_width; scr_h = mb->framebuffer_height; pitch = mb->framebuffer_pitch;

    init_mouse_hw();
    
    str_cpy(history[0], "TiwutOS");
    str_cpy(history[1], "v1.3");
    str_cpy(history[2], "Copyright (c) 2025 Tiwut");
    str_cpy(history[3], "Tiwut Basic Desktop Environment");

    redraw_scene();
    mouse_save();
    mouse_draw();

    char kbd[] = {0,0,'1','2','3','4','5','6','7','8','9','0','-','=','\b','\t','q','w','e','r','t','y','u','i','o','p','[',']','\n',0,'a','s','d','f','g','h','j','k','l',';','\'','`',0,'\\','z','x','c','v','b','n','m',',','.','/',0,'*',0,' '};

    while(1) {
        uint8_t status = inb(0x64);
        if(status & 1) {
            uint8_t scancode = inb(0x60);
            if(status & 0x20) {
                if(mouse_cycle==0 && (scancode & 0x08)) { 
                    mouse_byte[0]=scancode; mouse_cycle++; 
                }
                else if(mouse_cycle==1) { mouse_byte[1]=scancode; mouse_cycle++; }
                else if(mouse_cycle==2) {
                    mouse_byte[2]=scancode; mouse_cycle=0;
                    
                    int left_btn = mouse_byte[0] & 1;

                    if(left_btn) {
                        if(!win.dragging && !win.resizing) {
                            if(mx >= win.x && mx <= win.x+win.w && my >= win.y && my <= win.y+25) {
                                win.dragging = 1;
                                win.drag_off_x = mx - win.x;
                                win.drag_off_y = my - win.y;
                            }
                            else if(mx >= win.x+win.w-15 && mx <= win.x+win.w && my >= win.y+win.h-15 && my <= win.y+win.h) {
                                win.resizing = 1;
                            }
                        }
                    } else {
                        win.dragging = 0;
                        win.resizing = 0;
                    }

                    mouse_restore();
                    mx += mouse_byte[1]; my -= mouse_byte[2];
                    if(mx<0) mx=0; if(mx>790) mx=790;
                    if(my<0) my=0; if(my>590) my=590;

                    int need_redraw = 0;
                    if(win.dragging) {
                        win.x = mx - win.drag_off_x;
                        win.y = my - win.drag_off_y;
                        need_redraw = 1;
                    }
                    if(win.resizing) {
                        win.w = mx - win.x;
                        win.h = my - win.y;
                        if(win.w < 150) win.w = 150;
                        if(win.h < 100) win.h = 100;
                        need_redraw = 1;
                    }

                    if(need_redraw) redraw_scene();

                    mouse_save(); mouse_draw();
                }
            } 
            else if((scancode & 0x80) == 0) {
                char c = kbd[scancode];
                if(c) {
                    if(c == '\b') { if(term_idx > 0) { term_buf[--term_idx] = 0; refresh_term(); } }
                    else if(c == '\n') {
                        if(term_buf[0]=='h') add_history("Cmds: help, clear");
                        else if(term_buf[0]=='c') { clear_buffer(); add_history("Cleared."); }
                        else add_history("Unknown Command");
                        clear_buffer(); refresh_term();
                    }
                    else if(term_idx < 60) { term_buf[term_idx++] = c; term_buf[term_idx] = 0; refresh_term(); }
                }
            }
        }
    }
}