#include "lcd_pretty_effect.h"

#include <math.h>
#include <string.h>

#include "lcd_decode_image.h"

static uint16_t *s_pixels;
static int s_prev_frame = -1;
static int8_t s_xofs[PLATFORM_LCD_DEMO_IMAGE_W];
static int8_t s_yofs[PLATFORM_LCD_DEMO_IMAGE_H];
static int8_t s_xcomp[PLATFORM_LCD_DEMO_IMAGE_W];
static int8_t s_ycomp[PLATFORM_LCD_DEMO_IMAGE_H];

static inline uint16_t get_bgnd_pixel(int x, int y)
{
    return (uint16_t)*(s_pixels + (y * PLATFORM_LCD_DEMO_IMAGE_W) + x);
}

esp_err_t platform_lcd_pretty_effect_init(void)
{
    if (s_pixels != NULL) {
        return ESP_OK;
    }
    return platform_lcd_decode_image(&s_pixels);
}

void platform_lcd_pretty_effect_calc_lines(uint16_t *dest, int line, int frame, int linect)
{
    if (dest == NULL || linect <= 0) {
        return;
    }

    if (s_pixels == NULL) {
        memset(dest, 0, (size_t)PLATFORM_LCD_DEMO_IMAGE_W * (size_t)linect * sizeof(uint16_t));
        return;
    }

    if (frame != s_prev_frame) {
        for (int x = 0; x < PLATFORM_LCD_DEMO_IMAGE_W; x++) {
            s_xofs[x] = sin(frame * 0.15 + x * 0.06) * 4;
            s_xcomp[x] = sin(frame * 0.11 + x * 0.12) * 4;
        }
        for (int y = 0; y < PLATFORM_LCD_DEMO_IMAGE_H; y++) {
            s_yofs[y] = sin(frame * 0.1 + y * 0.05) * 4;
            s_ycomp[y] = sin(frame * 0.07 + y * 0.15) * 4;
        }
        s_prev_frame = frame;
    }

    for (int y = line; y < line + linect; y++) {
        for (int x = 0; x < PLATFORM_LCD_DEMO_IMAGE_W; x++) {
            int sample_x = x + s_yofs[y] + s_xcomp[x];
            int sample_y = y + s_xofs[x] + s_ycomp[y];

            if (sample_x < 0) {
                sample_x = 0;
            } else if (sample_x >= PLATFORM_LCD_DEMO_IMAGE_W) {
                sample_x = PLATFORM_LCD_DEMO_IMAGE_W - 1;
            }

            if (sample_y < 0) {
                sample_y = 0;
            } else if (sample_y >= PLATFORM_LCD_DEMO_IMAGE_H) {
                sample_y = PLATFORM_LCD_DEMO_IMAGE_H - 1;
            }

            *dest++ = get_bgnd_pixel(sample_x, sample_y);
        }
    }
}