#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <time.h>
#include <unistd.h>

/* Convert sRGB to Linear RGB */
double srgb_to_linear(double value) {
    if (value <= 0.04045) {
        return value / 12.92;
    } else {
        return pow((value + 0.055) / 1.055, 2.4);
    }
}

/* Convert Linear RGB to sRGB */
double linear_to_srgb(double value) {
    if (value <= 0.0031308) {
        return value * 12.92;
    } else {
        return 1.055 * pow(value, 1.0 / 2.4) - 0.055;
    }
}

/* Interpolate between two colors in Linear RGB space */
void interpolate_color_linear(const char *color1, const char *color2, double t, char *output) {
    unsigned int r1, g1, b1, r2, g2, b2;
    sscanf(color1, "#%02x%02x%02x", &r1, &g1, &b1);
    sscanf(color2, "#%02x%02x%02x", &r2, &g2, &b2);

    // Convert sRGB to linear RGB
    double lr1 = srgb_to_linear(r1 / 255.0);
    double lg1 = srgb_to_linear(g1 / 255.0);
    double lb1 = srgb_to_linear(b1 / 255.0);

    double lr2 = srgb_to_linear(r2 / 255.0);
    double lg2 = srgb_to_linear(g2 / 255.0);
    double lb2 = srgb_to_linear(b2 / 255.0);

    // Interpolate in linear RGB space
    double lr = lr1 + t * (lr2 - lr1);
    double lg = lg1 + t * (lg2 - lg1);
    double lb = lb1 + t * (lb2 - lb1);

    // Convert back to sRGB
    unsigned int r = (unsigned int)(linear_to_srgb(lr) * 255.0);
    unsigned int g = (unsigned int)(linear_to_srgb(lg) * 255.0);
    unsigned int b = (unsigned int)(linear_to_srgb(lb) * 255.0);

    // Format as hex output
    snprintf(output, 8, "#%02x%02x%02x", r, g, b);
}

int main() {
    /* Define the colors to cycle through */
    const char *breathing_colors[] = {
        "#ffe667", // Yellow
        "#f27049", // Orange
        "#3dd762", // Green
    };
    int color_count = sizeof(breathing_colors) / sizeof(breathing_colors[0]);

    int current_index = 0;
    double t = 0.0; // Interpolation factor
    char current_color[8];

    struct timespec ts = { 0, 5000000 }; // 5ms sleep

    while (1) {
        /* Interpolate the current color */
        interpolate_color_linear(
            breathing_colors[current_index],
            breathing_colors[(current_index + 1) % color_count],
            t,
            current_color
        );

        /* Write the current color to a file */
        FILE *f = fopen("/tmp/breathing_color", "w");
        if (f) {
            fprintf(f, "%s\n", current_color);
            fclose(f);
        }

        /* Increment interpolation factor */
        t += 0.005; // Adjust the speed of transition (smaller value = slower transition)
        if (t >= 1.0) {
            t = 0.0; // Reset interpolation
            current_index = (current_index + 1) % color_count; // Move to the next color
        }

        /* Sleep for 5ms */
        nanosleep(&ts, NULL);
    }

    return 0;
}