#include "stm32f0xx_hal.h"

#include "config.h"
#include "syslib.h"
#include "states.h"
#include "ssd1306.h"
#include "max31855.h"
#include "gpio.h"
#include "spi.h"
#include "flash.h"
#include "stringhelpers.h"
#include "display.h"
#include "storage.h"

#include "usb_device.h"
#include "usbd_cdc_if.h"


// Prototypes
void process();

therm_settings_t set;
therm_status_t status;

// Globalish setting vars
static __IO uint32_t TimingDelay;

int main(void)
{
    // Initialize HAL
    hal_init();

    // Configure the system clock
    systemclock_init();

    // Unset bootloader option bytes (if set)
    void bootloader_unset(void);

    // Init GPIO
    gpio_init();

    // Init USB (TODO: Handle plugged/unplugged with external power)
    MX_USB_DEVICE_Init();
//    set.val.usb_plugged = 

    // USB startup delay
    HAL_Delay(1000);
    HAL_GPIO_WritePin(LED_POWER, 1);

    // Enter into bootloader if up button pressed on boot
    if(!HAL_GPIO_ReadPin(SW_UP))
        bootloader_enter(); 

    // Init SPI busses
    spi_init();

    // Init OLED over SPI
    ssd1306_Init();
    ssd1306_clearscreen();
   
    // Default settings 
    set.val.boottobrew = 0;
    set.val.temp_units = TEMP_UNITS_CELSIUS;
    set.val.windup_guard = 1;
    set.val.k_p = 1;
    set.val.k_i = 1;
    set.val.k_d = 1;
    set.val.ignore_tc_error = 0;
    set.val.setpoint_brew = 0;
    set.val.setpoint_steam = 0;

    // Default status
    status.temp = 0;
    status.temp_frac = 0;
    status.state_resume = 0;
    status.state = STATE_IDLE;
    status.setpoint = 0;
    status.pid_enabled = 0;

    // Load settings (if any) from EEPROM
    restore_settings(&set);

    // Go to brew instead of idle if configured thusly
    if(set.val.boottobrew)
      status.state = STATE_PREHEAT_BREW; 

    // Startup screen 
    ssd1306_DrawString("therm v0.2", 1, 40);
    ssd1306_DrawString("protofusion.org/therm", 3, 0);

    HAL_Delay(1500);

    flash_restore(&set);

    HAL_Delay(1500);
    ssd1306_clearscreen();
 
    // Main loop
    while(1)
    {
        // Process sensor inputs
        process();

        // Run state machine
        display_process(&set, &status); 
    }

}

// PID implementation
// TODO: Make struct that has the last_temp and i_state in it, pass by ref. Make struct that has other input values maybe.
int16_t last_pid_temp = 0;
uint8_t last_pid_temp_frac = 0;
int32_t i_state = 0;

int16_t update_pid(uint16_t k_p, uint16_t k_i, uint16_t k_d, int16_t temp, uint8_t temp_frac, int16_t setpoint) 
{
  // Calculate instantaneous error
  int16_t error = setpoint - temp; // TODO: Use fixed point fraction

  // Proportional component
  int32_t p_term = k_p * error;

  // Error accumulator (integrator)
  i_state += error;

  // to prevent the iTerm getting huge from lots of 
  //  error, we use a "windup guard" 
  // (this happens when the machine is first turned on and
  // it cant help be cold despite its best efforts)
  // not necessary, but this makes windup guard values 
  // relative to the current iGain
  int32_t windup_guard_res = set.val.windup_guard / k_i;  

  // Calculate integral term with windup guard 
  if (i_state > windup_guard_res) 
    i_state = windup_guard_res;
  else if (i_state < -windup_guard_res) 
    i_state = -windup_guard_res;

  int32_t i_term = k_i * i_state;

  // Calculate differential term (slope since last iteration)
  int32_t d_term = (k_d * (status.temp - last_pid_temp));

  // Save temperature for next iteration
  last_pid_temp = status.temp;
  last_pid_temp_frac = status.temp_frac;

  int16_t result = p_term + i_term - d_term;

  // Put out tenths of percent, 0-1000. 
  if(result > 1000)
    result = 1000;
  else if(result < -1000)
    result = -1000;

  // Return feedback
  return result;
}


uint32_t last_ssr_on = 0;
uint32_t last_vcp_tx = 0;
uint32_t last_led = 0;
uint32_t last_pid = 0;
int16_t ssr_output = 0; // Duty cycle of ssr, 0 to SSR_PERIOD 

// Turn SSR output on/off according to set duty cycle.
// TODO: Eventually maybe replace with a very slow timer or something. Double-check this code...
void process()
{

    uint32_t ticks = HAL_GetTick();

    if(ticks - last_led > 400) 
    {
        last_led = ticks;
    }

    if((ticks - last_pid > PID_PERIOD))
    {
        #ifdef MAX31855_TC_SENSOR
        max31855_readtemp(spi_get(), &set, &status); // Read MAX31855
        #endif

        #ifdef MAX31865_RTD_SENSOR
        max31865_readtemp(&set, &status);
        #endif

    HAL_GPIO_TogglePin(LED_POWER);

        if(status.pid_enabled) 
        {
            // Get ssr output for next time
            int16_t power_percent = update_pid(set.val.k_p, set.val.k_i, set.val.k_d, status.temp, status.temp_frac, status.setpoint);
            //power-percent is 0-1000
            ssr_output = power_percent; //(((uint32_t)SSR_PERIOD * (uint32_t)10 * (uint32_t)100) * power_percent) / (uint32_t)1000000;
        }
        else 
        {
            ssr_output = 0;
        }

        last_pid = ticks;
    }

    // Every 200ms, set the SSR on unless output is 0
    if((ticks - last_ssr_on > SSR_PERIOD))
    {

        // Only support heating (ssr_output > 0) right now
        if(ssr_output > 0) {

            char tempstr[6];
            itoa(ssr_output, tempstr, 10);
            ssd1306_DrawString(tempstr, 0, 90);

            HAL_GPIO_WritePin(SSR_PIN, 1);
            last_ssr_on = ticks;
        }
    }
    
    // Kill SSR after elapsed period less than SSR_PERIOD 
    if(ticks - last_ssr_on > ssr_output || ssr_output == 0)
    {
        HAL_GPIO_WritePin(SSR_PIN, 0);
    }

    if(ticks - last_vcp_tx > VCP_TX_FREQ)
    {
        // Print temp to cdc
        char tempstr[16];
        itoa_fp(status.temp, status.temp_frac, tempstr);
        uint8_t numlen = strlen(tempstr);
        tempstr[numlen] = '\r';
        tempstr[numlen+1] = '\n';

//        if(set.val.usb_plugged)
//            CDC_Transmit_FS(tempstr, numlen+2);
       // while(CDC_Transmit_FS("\r\n", 2) == USBD_BUSY);

        last_vcp_tx = ticks;
    }
}

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