///
//
// leds.h defines structs and functions for addressing an HD107s ledstrip over serial using the GPIO pins.
//
///

#ifndef _potion_leds_h
#define _potion_leds_h

#include <stdint.h>
#include <stddef.h>
#include <unistd.h>
#include "shared.h"
#include "esp8266/gpio_register.h"
#include "esp_system.h"
#include "rom/ets_sys.h"
#include "driver/gpio.h"

// pack the struct to match exactly 8 * 4 = 32bits
struct __attribute__((__packed__)) led_components_t {
    // RGB component values
    uint8_t red;
    uint8_t green;
    uint8_t blue;
    uint8_t global; // global baseline brightness, highest 3 bits should always be ones
};

// union of components and their representation as a u32
// allows for easier sending of data over serial
union led_t {
    struct led_components_t components;
    uint32_t bits;
};

// point on a gradient
struct gradient_point_t {
    union led_t led;    // value of the led at this point
    size_t offset;      // offset (measured in leds) from the beginning
    short movement;     // direction of movement over time
};

struct gradient_t {
    struct gradient_point_t points[16]; // array of gradient points, support at most 16 points in a gradient
    size_t points_len;                           // number of used gradient points
    float duration;                       // amount of time to allow this gradient to last
                                          // positive means an amount in second 0 or negative means indefinitely until further notice
};

// buffer that will be written out to the led strip over serial
uint32_t g_serial_out_buffer[62];
// 60-long slice of the out buffer that represents the first few leds
union led_t* g_leds = ((union led_t*)g_serial_out_buffer + 1);

struct gradient_t g_default_gradient;
struct gradient_t g_current_gradient;
int g_leds_are_default = 1;

#define CLOCK 4
#define DATA 5

static
void leds_config_gpio() {
    gpio_config_t config = {
        .intr_type = GPIO_INTR_DISABLE,
        .mode = GPIO_MODE_OUTPUT,
        .pin_bit_mask = 0x18030,
        .pull_up_en = 0,
        .pull_down_en = 0,
    };
    gpio_config(&config);
    
}

static
void serial_write(int high) {
        // set clock out to high, triggering a rising edge
        gpio_set_level(CLOCK, 1);
        // write bit to data out
        gpio_set_level(DATA, high);

        os_delay_us(2);
        // set clock to low, triggering a falling edge, shifting the LEDs shift register
        gpio_set_level(CLOCK, 0);
}

static
void send_leds() {
    LOGLN("entering send_leds()");
    // index of the bit being written
    // fixed point number where the first 5 bits are the bit of a 32bit integger, and the rest is the integer
    int write_bit = 0;
    int write_next = 0;


    LOGLN("Setting clock low");

    gpio_set_level(CLOCK, 0);

    LOGLN("Writing to leds");

    while(write_bit < sizeof(g_serial_out_buffer) * 8) {
        // fetch the bit being addressed
        write_next = 0x1 & (g_serial_out_buffer[write_bit >> 5] >> (32 - (write_bit & 0x1F)));

        serial_write(write_next);

        write_bit++;
    }

    gpio_set_level(CLOCK, 0);
    gpio_set_level(DATA, 0);

}

static inline
uint8_t lerp_uint8(uint8_t a, uint8_t b, float t) {
    if(t <= 0) return a;
    else if(t >= 1.0) return b;
    else {
        int dir = b - a;
        return a + dir * t;
    }
}

static inline
void lerp_led(union led_t* out, const union led_t* from, const union led_t* to, float t) {
    out->components.red = lerp_uint8(from->components.red, to->components.red, t);
    out->components.green = lerp_uint8(from->components.green, to->components.green, t);
    out->components.blue = lerp_uint8(from->components.blue, to->components.blue, t);
    uint8_t glob_from = from->components.global & ~0xE0;
    uint8_t glob_to = to->components.global & ~0xE0;
    out->components.global = GLOBAL(lerp_uint8(glob_from, glob_to, t));
}

static inline
void lerp_points_between(const struct gradient_point_t from, const struct gradient_point_t to) {
    const int dif = to.offset - from.offset;
    float t = 0.f;
    for(int led = from.offset; led <= to.offset; ++led) {
        t = (float)(led - from.offset) / (float)dif;
        lerp_led(g_leds + led, &from.led, &to.led, t);
    }
}

static
void set_led_range(int start, int end, union led_t value) {
    for(int i = start; i < end; ++i) {
        g_leds[i] = value;
    }
}

static
void leds_set_default_gradient(const struct gradient_t* gradient) {
    g_default_gradient = *gradient;
}

static
void leds_set_current_gradient(const struct gradient_t* gradient, int defer_send) {
    struct gradient_point_t from = gradient->points[0];
    struct gradient_point_t to;

    set_led_range(0, gradient->points[0].offset, gradient->points[0].led);
    set_led_range(gradient->points[gradient->points_len-1].offset, 60, gradient->points[gradient->points_len-1].led);

    g_current_gradient = *gradient;

    for(int i = 1; i < gradient->points_len; ++i) {
        to = gradient->points[i];
        lerp_points_between(from, to);
        from = to;
    }

    if(!defer_send) {
        send_leds();
    }
}

static
void leds_init() {
    g_serial_out_buffer[0] = 0u;
    g_serial_out_buffer[61] = ~0u;
    set_led_range(0, 60,
        (union led_t){.components = 
        (struct led_components_t) {
            .red = 0,
            .green = 0,
            .blue = 0,
            .global = GLOBAL(5)
        }}
    );

    leds_config_gpio();
}

#endif // !_leds_h