#ifndef TEXT_H
#define TEXT_H

#include "posprintf.h"

typedef void (*TxtDrawc)(char c, size_t x, size_t y, u8 clr);
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;

    u8 buffer[30 * 20];
    u8 spacing;
    u8 color;
    TxtDrawc drawc;
} TextEngine;

static TextEngine text_engine = {0};

// Initializes the text engine.
static inline
void
txt_init(TxtDrawc drawc) {
    // Initialize remaining variables.
    text_engine.spacing = 8;
    text_engine.color = 1;
    text_engine.drawc = drawc;
}

// 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.buffer[x + 30 * y] = 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) {
    dma_fill(text_engine.buffer, 0, sizeof(text_engine.buffer), 3);
    text_engine.cursor_x = 0;
    text_engine.cursor_y = 0;
}

// Clears the screen on the tile text mode.
static inline
void
txt_clear(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;
}

static inline
void
txt_color(u8 clr) {
    text_engine.color = clr;
}

static inline
void
txt_spacing(u8 spacing) {
    text_engine.spacing = spacing;
}

// Renders the contents of the scrollback buffer to the screen.
void
txt_render(void) {
    for (size_t y = 0; y < 20; y++) {
        for (size_t x = 0; x < 30; x++) {
            size_t pos = x + y * 30;
            if (text_engine.buffer[pos] == 0) {
                continue;
            }
            text_engine.drawc(
                    text_engine.buffer[pos],
                    x * text_engine.spacing,
                    y * text_engine.spacing,
                    text_engine.color);
        }
    }
}

// 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, u8 clr) {
    size_t i = 0;
    while (*msg) {
        char c = *msg++;
        text_engine.drawc(c, x + i++ * text_engine.spacing, y, clr);
    }
}

// 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, c, ...) \
	{ \
		char buf[256] = {0}; \
		posprintf(buf, msg, ##__VA_ARGS__); \
		txt_draws(buf, x, y, c); \
	}

#endif // TEXT_H