#ifndef TEXT_H
#define TEXT_H

#include "posprintf.h"
#include "renderer.h"

#include "font.h"

typedef struct TextEngine {
    // Cursor for tiled text mode The X and Y positions correspond to the tile
    // X and Y starting from the top left of the screen. For a 240x160 screen,
    // we have 30x20 tiles available.
    size_t cursor_x;
    size_t cursor_y;

    // Memory location of font tile data and tilemap. Likely located on the
    // VRAM.
    u32 *font_data;
    u16 *font_tilemap;

    // The font map for tiled text. Writing the character stored in this
    // position on the tilemap will show a character on the screen.
    u16 font_map[256];
} TextEngine;

static TextEngine text_engine = {0};

// Initializes the text engine.
static inline
void
txt_init(u32 *font_data, u16 *font_tilemap, u16 font_offset) {
    // Load font data into VRAM.
    unpack_tiles(&font, font_data, 256);

    // Initialize the font map translation table. That way we can write
    // a character on the text background layer with:
    //     FONT_TILEMAP[tile_x + 32 * tile_y] = font_map['A'];
    for (size_t i = 0; i < 256; ++i) {
        text_engine.font_map[i] = font_offset + i;
    }

    // Initialize remaining variables.
    text_engine.font_data = font_data;
    text_engine.font_tilemap = font_tilemap;
}

// Writes a message to the tile text background.
static inline
void
txt_puts(char *msg) {
    while (*msg) {
        char c = *msg++;
        if (c == '\0') {
            continue;
        }
        if (c == '\n') {
            text_engine.cursor_x = 0;
            text_engine.cursor_y++;
        } else {
            int x = text_engine.cursor_x;
            int y = text_engine.cursor_y;
            text_engine.font_tilemap[x + 32 * y] = text_engine.font_map[(u16)c];
            text_engine.cursor_x += 1;
            if (text_engine.cursor_x >= 30) {
                text_engine.cursor_x = 0;
                text_engine.cursor_y++;
            }
        }
        if (text_engine.cursor_y >= 20) {
            text_engine.cursor_y = 0;
        }
    }
}

// Clears the current line on the tile text mode.
static inline
void
txt_clear_line(void) {
    for (size_t i = 0; i < 30; ++i) {
        int x = text_engine.cursor_x;
        int y = text_engine.cursor_y;
        text_engine.font_tilemap[x + 32 * y] = text_engine.font_map[0];
    }
    text_engine.cursor_x = 0;
}

// Clears the screen on the tile text mode.
static inline
void
txt_clear_screen(void) {
    for (size_t j = 0; j < 20; ++j) {
        text_engine.cursor_y = j;
        txt_clear_line();
    }
    text_engine.cursor_x = 0;
    text_engine.cursor_y = 0;
}

// Moves the tile mode cursor to the specified position.
static inline
void
txt_position(size_t tile_x, size_t tile_y) {
    text_engine.cursor_x = tile_x;
    text_engine.cursor_y = tile_y;
}

// Draws a message where the first character's top-left corner begins at the
// given x and y position. The character spacing can be adjusted, but beware of
// color merging issues.
static inline
void
txt_draws(char *msg, size_t x, size_t y, size_t spacing, u8 clr) {
    while (*msg) {
        char c = *msg++;
        Tile *tile = FONT_DATA;
        tile += c;
        draw_tile(x, y, tile, clr, true);
        x += spacing;
    }
}

static inline
void
txt_drawc(char c, size_t x, size_t y, size_t spacing, u8 clr) {
    Tile *tile = FONT_DATA;
    tile += c;
    draw_tile(x, y, tile, clr, true);
    x += spacing;
}

// Print text to the screen with formatting.
#define txt_printf(msg, ...) \
	{ \
		char buf[256] = {0}; \
		posprintf(buf, msg, ##__VA_ARGS__); \
		txt_puts(buf); \
	}

// Draws text to the screen with formatting starting on the x and y position and
// with custom character spacing.
#define txt_drawf(msg, x, y, s, c, ...) \
	{ \
		char buf[256] = {0}; \
		posprintf(buf, msg, ##__VA_ARGS__); \
		txt_draws(buf, x, y, s, c); \
	}

// Small font is located after the initial ASCII characters, and only supports
// lowercase characters.
// NOTE: Slow, we should do this with a LUT.
#define txt_drawf_small(msg, x, y, s, c, ...) \
	{ \
		char buf[256] = {0}; \
		posprintf(buf, msg, ##__VA_ARGS__); \
		for (size_t i = 0; i < 256; i++) { \
		    if (buf[i] == 0) { \
		        break; \
		    } \
		    if (buf[i] < 'a') { \
                buf[i] += 16 * 6; \
		    } else { \
                buf[i] += 16 * 4; \
		    }\
		} \
		txt_draws(buf, x, y, s, c); \
	}

#endif // TEXT_H