#ifndef GBAEXP_BITMAP_H
#define GBAEXP_BITMAP_H

// #include "bd-font.c"
#include "common.h"

// Using bd-font, an 8x8 bitmap font.
// static void
// put_char(int x, int y, Color clr, u8 chr) {
//     for (size_t i = 0; i < 8; ++i) {
//         for (size_t j = 0; j < 8; ++j) {
//             if ((font[chr][i] >> (7 - j)) & 0x1) {
//                 FRAMEBUFFER[y + i][x + j] = clr;
//             }
//         }
//     }
// }

// static void
// put_text(int x, int y, Color clr, char *msg) {
//     int count = 0;
//     while (*msg) {
//         put_char(x + count, y, clr, *msg++);
//         count += 8;
//     }
// }

// Draws a line with the given color between (x0,y0) and (x1,y1) using the
// Bresenham's line drawing algorithm using exclusively integer arithmetic.
static void
draw_line(int x0, int y0, int x1, int y1, Color clr) {
    // Pointer to the initial position of the screen buffer where we will start
    // writing our data.
    vu16 *destination = (u16*)(SCREEN_BUFFER + y0 * SCREEN_WIDTH + x0);

    // Adjust the step direction and calculate deltas.
    int x_step;
    int y_step;
    int dx;
    int dy;
    if (x0 > x1) {
        x_step = -1;
        dx = x0 - x1;
    } else {
        x_step = 1;
        dx = x1 - x0;
    }
    if (y0 > y1) {
        y_step = -SCREEN_WIDTH;
        dy = y0 - y1;
    } else {
        y_step = +SCREEN_WIDTH;
        dy = y1 - y0;
    }

    if(dy == 0) {
        // Horizontal line.
        for(int i = 0; i <= dx; i++) {
            destination[i * x_step] = clr;
        }
    } else if(dx == 0) {
        // Vertical line.
        for(int i = 0; i <= dy; i++) {
            destination[i * y_step] = clr;
        }
    } else if (dx >= dy){
        // Positive slope.
        int diff = 2 * dy - dx;
        for (int i = 0; i <= dx; ++i) {
            *destination = clr;
            if (diff >= 0) {
                destination += y_step;
                diff -= 2 * dx;
            }
            destination += x_step;
            diff += 2 * dy;
        }
    } else {
        // Negative slope.
        int diff = 2 * dx - dy;
        for (int i = 0; i <= dy; ++i) {
            *destination = clr;
            if (diff >= 0) {
                destination += x_step;
                diff -= 2 * dy;
            }
            destination += y_step;
            diff += 2 * dx;
        }
    }
}

static inline void
draw_rect(int x0, int y0, int x1, int y1, Color clr) {
    if (x0 > x1) {
        int tmp = x0;
        x0 = x1;
        x1 = tmp;
    }
    if (y0 > y1) {
        int tmp = y0;
        y0 = y1;
        y1 = tmp;
    }
    int dx = x1 - x0;
    int dy = y1 - y0;
    for (int i = 0; i <= dx; ++i) {
        int x = x0 + i;
        FRAMEBUFFER[y0][x] = clr;
        FRAMEBUFFER[y1][x] = clr;
    }
    for (int j = 0; j <= dy; ++j) {
        int y = y0 + j;
        FRAMEBUFFER[y][x0] = clr;
        FRAMEBUFFER[y][x1] = clr;
    }
}

static inline void
draw_fill_rect(int x0, int y0, int x1, int y1, Color clr) {
    if (x0 > x1) {
        int tmp = x0;
        x0 = x1;
        x1 = tmp;
    }
    if (y0 > y1) {
        int tmp = y0;
        y0 = y1;
        y1 = tmp;
    }
    int dx = x1 - x0;
    int dy = y1 - y0;
    for (int i = 0; i <= dx; ++i) {
        for (int j = 0; j <= dy; ++j) {
            int x = x0 + i;
            int y = y0 + j;
            FRAMEBUFFER[y][x] = clr;
        }
    }
}

// In Mode4 the buffer is of 8 bytes per pixel instead of 16. We can't write the
// color directly, instead the color is stored in the palette memory at
// `MEM_PAL`. Note that in this mode MEM_PAL[0] is the background color. This
// plotter takes an index to a color stored in MEM_PAL[col_index]. Because the
// GBA needs to meet memory alignment requirements, we can't write a u8 into
// memory, instead we need to read a u16 word, mask and or the corresponding
// bits and wave the updated u16.
static void
put_pixel_m4(int x, int y, u8 col_index, vu16 *buffer) {
    int buffer_index = (y * SCREEN_WIDTH + x) / 2;
    vu16 *destination = &buffer[buffer_index];
    // Odd pixels will go to the top 8 bits of the destination. Even pixels to
    // the lower 8 bits.
    int odd = x & 0x1;
    if(odd) {
        *destination= (*destination & 0xFF) | (col_index << 8);
    } else {
        *destination= (*destination & ~0xFF) |  col_index;
    }
}

static void
draw_fill_rect_m4(int x0, int y0, int x1, int y1, u8 col_index, vu16 *buffer) {
    int ix, iy;
    for(iy = y0; iy < y1; iy++) {
        for(ix = x0; ix < x1; ix++) {
            put_pixel_m4(ix, iy, col_index, buffer);
        }
    }
}

void
draw_logo(void) {
    int side = 60;
    int line = 35;
    int height = side * 0.5;
    int x = SCREEN_WIDTH / 2 - height / 2;
    int y = SCREEN_HEIGHT / 2;

    // Draw red triangle.
    draw_line(x + height - 1, y - side / 2, x, y - 1, COLOR_RED);
    draw_line(x + height - 1, y + side / 2, x, y + 1, COLOR_RED);
    draw_line(x + height - 1, y - side / 2 + 1, x, y, COLOR_RED);
    draw_line(x + height - 1, y + side / 2 - 1, x, y, COLOR_RED);

    // Draw white triangle.
    draw_line(x, y - side / 2, x, y + side / 2, COLOR_WHITE);
    draw_line(x + 1, y - side / 2, x + height, y - 1, COLOR_WHITE);
    draw_line(x + 1, y + side / 2, x + height, y + 1, COLOR_WHITE);

    // Draw white line at triangle tip.
    draw_line(x + height, y - side / 2, x + height, y + side / 2, COLOR_WHITE);
    draw_line(x + height + 1, y - side / 2, x + height + 1, y + side / 2, COLOR_WHITE);

    // Double triangle line.
    draw_line(x - 1, y - side / 2, x - 1, y + side / 2, COLOR_WHITE);
    draw_line(x + 1, y - side / 2 + 1, x + height, y, COLOR_WHITE);
    draw_line(x + 1, y + side / 2 - 1, x + height, y, COLOR_WHITE);

    // Draw white lines.
    draw_line(x - line, y, x, y, COLOR_WHITE);
    draw_line(x + height, y, x + height + line, y, COLOR_WHITE);
    draw_line(x - line, y + 1, x, y + 1, COLOR_WHITE);
    draw_line(x + height, y + 1, x + height + line, y + 1, COLOR_WHITE);
}

// void
// copy_font_to_tile_memory(Tile *tile) {
//     // Hex to bits translation table.
//     const u32 conversion_u32[16] = {
//         0x00000000, 0x00001000, 0x00000100, 0x00001100,
//         0x00000010, 0x00001010, 0x00000110, 0x00001110,
//         0x00000001, 0x00001001, 0x00000101, 0x00001101,
//         0x00000011, 0x00001011, 0x00000111, 0x00001111,
//     };
//     for (size_t i = 0; i < 250; ++i) {
//         for (size_t j = 0; j < 8; ++j) {
//             u8 row = font[i][j];
//             u32 tile_idx = 0x00000000;
//             tile_idx = conversion_u32[row & 0xF] << 16;
//             tile_idx |= conversion_u32[(row >> 4) & 0xF];
//             (tile + i)->data[j] = tile_idx;
//         }
//     }
// }

#endif // GBAEXP_BITMAP_H