#include <stdint.h>
#include <string.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#include <stdbool.h>
#include <stddef.h>

#include "software_pwm.h"
#include "pins.h"


static struct link_pair {
  struct pwm_event *next; 
  struct pwm_event *prev;
};

//if next is ever zero, node is assumed not part of list/disabled
static struct pwm_event {
  struct link_pair active;
  struct link_pair twins;
  uint8_t time;
  uint8_t pins;
  bool enabled;
} events[SOFTPWM_PIN_COUNT + 1];


#define LIST_INSERT(new, former, member) (\
    list_insert(&(new.member), &(former.member), offsetof(struct pwm_event, time)))

static void list_insert(struct link_pair *new_links, struct link_pair *former_links, size_t parent_offset) {

}

static void list_remove(struct link_pair *event) {
}

void init_softpwm() {

  //this one never moves
  events[SOFTPWM_PIN_COUNT].time = 0;
  events[SOFTPWM_PIN_COUNT].pins = 0;
  events[SOFTPWM_PIN_COUNT].active.next = &events[SOFTPWM_PIN_COUNT];
  events[SOFTPWM_PIN_COUNT].active.prev = &events[SOFTPWM_PIN_COUNT];
  events[SOFTPWM_PIN_COUNT].enabled = true;

  //TODO: move all to zero once init_softpwm tested
  for(size_t event_i = 0; event_i < SOFTPWM_PIN_COUNT; event_i++) {
    events[event_i].time = event_i;
    events[event_i].pins = (1 << (event_i + 1)) - 1;
    LIST_INSERT(events[event_i], events[((int)event_i - 1) % (SOFTPWM_PIN_COUNT + 1)], active);
  }

  SOFTPWM_DDR = 0xff; 

  //use external 10mhz clock (we just have one laying around)
  //then prescale by 1024. Check at different freqs for brightness
  TCCR0A = 0b00000010;
  TIMSK0 = 0b00000011;
  OCR0A = events[SOFTPWM_PIN_COUNT].time;
  TIFR0 = 0b00000010; //interupts enabled!
  sei();
}

void softpwm_set(uint8_t pin, uint8_t duty) { 
  /**
  struct pwm_event *event_unmoved = &events[pin]; //TODO describe if you want ig
  struct pwm_event *this_event = &events[pin];
  this_event->time = duty;
  if(duty < events[pin].time) {
    while(duty < event_unmoved->time) event_unmoved = event_unmoved->next;
  }
  else {
  }
  **/
}

/**
ISR(TIMER0_OVF_vect) {
}
**/

ISR(TIMER0_COMP_vect) {
  /**
  static struct pwm_event *on_event = &events[SOFTPWM_PIN_COUNT];
  SOFTPWM_PORT = on_event->pins;
  on_event = on_event->next;
  OCR0A = on_event->time;
  **/
}