package effects

import (
	"fmt"
	"git.aiterp.net/lucifer3/server/device"
	"math"
	"strings"
)

func statesDescription(states []device.State) string {
	sb := strings.Builder{}
	sb.Grow(128)

	sb.WriteRune('[')
	for i, state := range states {
		if i > 0 {
			sb.WriteString(", ")
		}

		sb.WriteString(state.String())
	}
	sb.WriteRune(']')

	return sb.String()
}

func gradientState(states []device.State, interpolate bool, index, length int) device.State {
	indexFactor := math.Min(float64(index)/float64(length-1), 1)

	return gradientStateFactor(states, interpolate, indexFactor)
}

func gradientStateFactor(states []device.State, interpolate bool, factor float64) device.State {
	var stateIncrement float64
	if interpolate {
		stateIncrement = 1.0 / float64(len(states)-1)
	} else {
		stateIncrement = 1.0 / float64(len(states))
	}

	for i := range states {
		a := float64(i) * stateIncrement
		b := float64(i+1) * stateIncrement

		if factor >= a && factor < b {
			si := states[i]
			if !interpolate || i+1 == len(states) {
				return si
			}
			sj := states[i+1]

			f := (factor - a) / stateIncrement

			if f < 0 || f > 1 {
				panic(fmt.Sprintf("assert(0 <= f <= 1) f = %.2f (if = %.2f, a = %.2f, si = %.2f)", f, factor, a, stateIncrement))
			}

			return si.Interpolate(sj, f)
		}
	}

	return states[len(states)-1]
}