#include "pid.h"
#include "Timer.h"
#define _constrain(amt, low, high)                                             \
	((amt) < (low) ? (low) : ((amt) > (high) ? (high) : (amt)))
#include "Can.h"

extern CAN_transmiter CAN0_transmiter;

PIDController::PIDController(float P, float I, float D, float ramp, float limit)
	: P(P), I(I), D(D), output_ramp(ramp) // PID控制器加速度限幅
	  ,
	  limit(limit) // PID控制器输出限幅
	  ,
	  error_prev(0.0f), output_prev(0.0f), integral_prev(0.0f) {
	timestamp_prev = get_system_runtime_us();
}

// PID 控制器函数
float PIDController::operator()(float error) {
	// 计算两次循环中间的间隔时间
	unsigned long timestamp_now = get_system_runtime_us();
	float Ts = (timestamp_now - timestamp_prev) * 1e-6f;
	if (Ts <= 0 || Ts > 0.5f)
		Ts = 1e-3f;

	// P环
	float proportional = P * error;
	// Tustin 散点积分（I环）
	float integral = integral_prev + I * Ts * 0.5f * (error + error_prev);
	integral = _constrain(integral, -limit, limit);
	// D环（微分环节）
	float derivative = D * (error - error_prev) / Ts;
	// 将P,I,D三环的计算值加起来
	float output = proportional + integral + derivative;
	output = _constrain(output, -limit, limit);

	if (output_ramp > 0) {
		// 对PID的变化速率进行限制
		float output_rate = (output - output_prev) / Ts;
		if (output_rate > output_ramp)
			output = output_prev + output_ramp * Ts;
		else if (output_rate < -output_ramp)
			output = output_prev - output_ramp * Ts;
	}
	// 保存值（为了下一次循环）
	integral_prev = integral;
	output_prev = output;
	error_prev = error;
	timestamp_prev = timestamp_now;

	return output;
}

/**
 * @brief 设置PID参数
 *
 * @param P: P参数
 * @param I: I参数
 * @param D: D参数
 * @return void
 */
void PIDController::set_PID(float P, float I, float D) {
	P = P;
	I = I;
	D = D;
}