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#include <gtest/gtest.h>
#include <PID.hpp>

TEST(PIDTest, AllZeroCase)
{
	PID pid;
	EXPECT_FLOAT_EQ(pid.update(0.f, 0.f, false), 0.f);
}

TEST(PIDTest, OutputLimit)
{
	PID pid;
	pid.setOutputLimit(.01f);
	pid.setGains(.1f, 0.f, 0.f);
	pid.setSetpoint(1.f);
	EXPECT_FLOAT_EQ(pid.update(0.f, 0.f, false), .01f);
	EXPECT_FLOAT_EQ(pid.update(.9f, 0.f, false), .01f);
	EXPECT_NEAR(pid.update(.95f, 0.f, false), .005f, 1e-6f);
	EXPECT_FLOAT_EQ(pid.update(1.f, 0.f, false), 0.f);
	EXPECT_NEAR(pid.update(1.05f, 0.f, false), -.005f, 1e-6f);
	EXPECT_FLOAT_EQ(pid.update(1.1f, 0.f, false), -.01f);
	EXPECT_FLOAT_EQ(pid.update(1.15f, 0.f, false), -.01f);
	EXPECT_FLOAT_EQ(pid.update(2.f, 0.f, false), -.01f);
}

TEST(PIDTest, ProportinalOnly)
{
	PID pid;
	pid.setOutputLimit(1.f);
	pid.setGains(.1f, 0.f, 0.f);
	EXPECT_FLOAT_EQ(pid.update(0.f, 0.f, false), 0.f);
	pid.setSetpoint(1.f);
	EXPECT_FLOAT_EQ(pid.update(0.f, 0.f, false), .1f);
	EXPECT_FLOAT_EQ(pid.update(1.f, 0.f, false), 0.f);

	float plant = 0.f;
	float output = 10000.f;
	int i; // need function scope to check how many steps

	for (i = 1000; i > 0; i--) {
		const float output_new = pid.update(plant, 0.f, false);
		plant += output_new;

		// expect the output to get smaller with each iteration
		if (output_new >= output) {
			break;
		}

		output = output_new;
	}

	EXPECT_FLOAT_EQ(plant, 1.f);
	EXPECT_GT(i, 0); // it shouldn't have taken longer than an iteration timeout to converge
}

TEST(PIDTest, InteralOpenLoop)
{
	PID pid;
	pid.setOutputLimit(1.f);
	pid.setGains(0.f, .1f, 0.f);
	pid.setIntegralLimit(.05f);
	pid.setSetpoint(1.f);

	// Zero error
	EXPECT_FLOAT_EQ(pid.update(1.f, 0.f, true), 0.f);
	EXPECT_FLOAT_EQ(pid.update(1.f, 0.f, true), 0.f);
	EXPECT_FLOAT_EQ(pid.update(1.f, 0.f, true), 0.f);

	// Open loop ramp up
	EXPECT_FLOAT_EQ(pid.update(0.f, 0.1f, true), 0.f);
	EXPECT_FLOAT_EQ(pid.update(0.f, 0.1f, true), .01f);
	EXPECT_FLOAT_EQ(pid.update(0.f, 0.1f, true), .02f);
	EXPECT_FLOAT_EQ(pid.update(0.f, 0.1f, true), .03f);
	EXPECT_FLOAT_EQ(pid.update(0.f, 0.1f, true), .04f);
	EXPECT_FLOAT_EQ(pid.update(0.f, 0.1f, true), .05f);
	EXPECT_FLOAT_EQ(pid.update(0.f, 0.1f, true), .05f);
	EXPECT_FLOAT_EQ(pid.update(0.f, 0.1f, true), .05f);

	// Open loop ramp down
	pid.setSetpoint(-1.f);
	EXPECT_FLOAT_EQ(pid.update(0.f, 0.1f, true), .05f);
	EXPECT_FLOAT_EQ(pid.update(0.f, 0.1f, true), .04f);
	EXPECT_FLOAT_EQ(pid.update(0.f, 0.1f, true), .03f);
	EXPECT_FLOAT_EQ(pid.update(0.f, 0.1f, true), .02f);
	EXPECT_NEAR(pid.update(0.f, 0.1f, true), .01f, 1e-6f);
	EXPECT_NEAR(pid.update(0.f, 0.1f, true), 0.f, 1e-6f);
	EXPECT_NEAR(pid.update(0.f, 0.1f, true), -.01f, 1e-6f);
	EXPECT_FLOAT_EQ(pid.update(0.f, 0.1f, true), -.02f);
	EXPECT_NEAR(pid.update(0.f, 0.1f, true), -.03f, 1e-6f);
	EXPECT_FLOAT_EQ(pid.update(0.f, 0.1f, true), -.04f);
	EXPECT_FLOAT_EQ(pid.update(0.f, 0.1f, true), -.05f);
	EXPECT_FLOAT_EQ(pid.update(0.f, 0.1f, true), -.05f);
	EXPECT_FLOAT_EQ(pid.update(0.f, 0.1f, true), -.05f);
	pid.resetIntegral();
	EXPECT_FLOAT_EQ(pid.update(0.f, 0.1f, true), -.01f);
}