package thermocouple

import (
	"math"
	"th7/data/thermocouple"
)

const (
	K_MAX_C  = 1372.0
	K_MIN_C  = -270.0
	K_MAX_UV = 54886.0
	K_MIN_UV = -5891.0
)

func k_c_to_uv(c float64) (float64, error) {

	if c < K_MIN_C || c > K_MAX_C {
		return 0, thermocouple.ErrC
	}

	var c0, c1, c2, c3, c4, c5, c6, c7, c8, c9, c10 float64
	var t, et, E, a0, a1 float64

	a0 = 1.185976e2
	a1 = -1.183432e-4

	if c < 0.0 {
		c0 = 0.0
		c1 = 3.9450128025e1
		c2 = 2.3622373598e-2
		c3 = -3.2858906784e-4
		c4 = -4.9904828777e-6
		c5 = -6.7509059173e-8
		c6 = -5.7410327428e-10
		c7 = -3.1088872894e-12
		c8 = -1.0451609365e-14
		c9 = -1.9889266878e-17
		c10 = -1.6322697486e-20
		et = 0.0
	} else {
		c0 = -1.7600413686e1
		c1 = 3.8921204975e1
		c2 = 1.8558770032e-2
		c3 = -9.9457592874e-5
		c4 = 3.1840945719e-7
		c5 = -5.6072844889e-10
		c6 = 5.6075059059e-13
		c7 = -3.2020720003e-16
		c8 = 9.7151147152e-20
		c9 = -1.2104721275e-23
		c10 = 0.0
		t = c
		t -= 126.9686
		t = t * t
		t = t * a1
		et = math.Exp(t) * a0
	}
	t = c
	E = c0 + t*(c1+t*(c2+t*(c3+t*(c4+t*(c5+t*(c6+t*(c7+t*(c8+t*(c9+t*(c10)))))))))) + et
	return E, nil
}

func k_uv_to_c(uv float64) (float64, error) {

	if uv < K_MIN_UV || uv > K_MAX_UV {
		return 0, thermocouple.ErrUV
	}

	var c0, c1, c2, c3, c4, c5, c6, c7, c8, c9, T float64

	if uv < 0.0 {
		c0 = 0.0
		c1 = 2.5173462e-2
		c2 = -1.1662878e-6
		c3 = -1.0833638e-9
		c4 = -8.9773540e-13
		c5 = -3.7342377e-16
		c6 = -8.6632643e-20
		c7 = -1.0450598e-23
		c8 = -5.1920577e-28
		c9 = 0.0
	} else if uv < 20644.0 {
		c0 = 0.0
		c1 = 2.508335e-2
		c2 = 7.860106e-8
		c3 = -2.503131e-10
		c4 = 8.315270e-14
		c5 = -1.228034e-17
		c6 = 9.804036e-22
		c7 = -4.413030e-26
		c8 = 1.057734e-30
		c9 = -1.052755e-35
	} else {
		c0 = -1.318058e2
		c1 = 4.830222e-2
		c2 = -1.646031e-6
		c3 = 5.464731e-11
		c4 = -9.650715e-16
		c5 = 8.802193e-21
		c6 = -3.110810e-26
		c7 = 0.0
		c8 = 0.0
		c9 = 0.0
	}

	T = c0 + uv*(c1+uv*(c2+uv*(c3+uv*(c4+uv*(c5+uv*(c6+uv*(c7+uv*(c8+uv*(c9)))))))))
	return T, nil
}