#include "leds.h"

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

uint32_t g_serial_out_buffer[122];
Led* g_leds = ((Led*)g_serial_out_buffer + 1);

Gradient g_default_gradient;
Gradient g_current_gradient;
int g_leds_are_default = 1;
LedsSendStatus g_leds_send_state = LEDS_SEND_WAITING;

SemaphoreHandle_t g_led_mutex; // mutex governing access to data for leds
                               // use for all global data defined in this header

LedThreadData g_led_thread_data = {
    .task = 0,
    .func = &leds_thread
};

/// =======================================
// leds.h internal helper functions
/// =======================================

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(Led* out, const Led* from, const Led* 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 GradientPoint from, const GradientPoint 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 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);

    ets_delay_us(1);

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


/// =======================================
// leds.h external interface functions
/// =======================================


void 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;

    gpio_set_level(CLOCK, 0);

    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);

}

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

void leds_set_default_gradient(const Gradient* gradient) {
    g_default_gradient = *gradient;
}

void leds_set_current_gradient(const Gradient* gradient, int defer_send) {
    GradientPoint from = gradient->points[0];
    GradientPoint to;

    set_led_range(0, gradient->points[0].offset, gradient->points[0].led);
    set_led_range(gradient->points[gradient->points_len-1].offset, 120, 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();
    }
}

void leds_reset_gradient(int defer_send) {
    leds_set_current_gradient(&g_default_gradient, defer_send);
}

// swap to ranges of memory using a temporary block
static
void memswap(void* d, void* s, size_t n) {
    void* tmp = malloc(n);
    memcpy(tmp, s, n);
    memcpy(s, d, n);
    memcpy(d, tmp, n);
    free(tmp);
}

void leds_animate() {
    for(size_t i = 0; i < g_current_gradient.points_len; ++i) {
        // The gradient point at i
        GradientPoint* point = g_current_gradient.points + i;
        // move towards end
        if(point->movement > 0) {
            // without moving past it
            point->offset = min(point->offset + 1, 120);

            // swap with next point if we pass it
            if(point->offset > (point+1)->offset) {
                memswap(point, point+1, sizeof(GradientPoint));
            }
        // move towards start
        } else if(point->movement < 0) {
            // without passing it
            point->offset = max(0, point->offset - 1);

            // swap with previous point if we fall below it
            if(point->offset < (point-1)->offset) {
                memswap(point, point-1, sizeof(GradientPoint));
            }
        }
    }
    leds_set_current_gradient(&g_current_gradient, 1);
}

void leds_thread() {
    send_leds();
    float timer = 0;
    for(;;) {
        // wait for 10 milliseconds,
        // giving FreeRTOS time to run other tasks
        vTaskDelay(10 / portTICK_RATE_MS);
        // tick timer by 10ms
        timer += 0.01;
        xSemaphoreTake(g_led_mutex, portMAX_DELAY);
        {
            send_leds();
            leds_animate();

            // reset gradient, defer send until next frame
            if(timer > g_current_gradient.duration) {
                timer = 0.f;
                leds_reset_gradient(1);
            }
        }
        xSemaphoreGive(g_led_mutex);
    }
}

void leds_init() {
    g_serial_out_buffer[0] = 0u;
    g_serial_out_buffer[61] = ~0u;
    set_led_range(0, 120,
        (Led){.components = 
        (LedComponents) {
            .red = 0,
            .green = 0,
            .blue = 0,
            .global = GLOBAL(5)
        }}
    );

    g_led_mutex = xSemaphoreCreateMutex();

    xTaskCreate(g_led_thread_data.func, "Leds", 1024, NULL, 1, &g_led_thread_data.task);

    // initialize mutex for leds data
    leds_config_gpio();
}