package com.vgmlr.kiln

import androidx.compose.ui.graphics.Color
import java.time.LocalDate
import java.time.temporal.ChronoUnit
import kotlin.math.roundToInt

object KilnGradientPalette {
    
    const val PRE_MENSTRUAL_BUCKET = 2
    
    fun hueFor(date: LocalDate, lastStart: LocalDate?, cycle: Int, moodShift: Float = 0f): Float {
        if (lastStart == null) return 120f
        val phase = Math.floorMod(
            ChronoUnit.DAYS.between(lastStart, date), cycle.toLong()
        ).toFloat()
        val greenPeak = 7f
        val redStart = (cycle - 6f).coerceAtLeast(greenPeak)
        val redEnd = cycle - 1f
        val base = when {
            phase in greenPeak..redStart ->
                120f * (1f - (phase - greenPeak) / (redStart - greenPeak))
            phase > redStart && phase < redEnd -> 0f
            else -> {
                val fromRed = if (phase >= redEnd) phase - redEnd else phase + (cycle - redEnd)
                120f * (fromRed / ((cycle - redEnd) + greenPeak))
            }
        }
        return (base + moodShift).coerceIn(0f, 120f)
    }

    fun colorFor(hue: Float): Color = Color.hsv(hue, 0.50f, 0.95f)

    fun bucket(hue: Float): Int = ((hue / 120f) * 7f).roundToInt().coerceIn(0, 7)

    fun isPreMenstrual(hue: Float): Boolean = bucket(hue) <= PRE_MENSTRUAL_BUCKET

    fun lookup(
        records: List<KilnDayRecord>,
        buttons: KilnButtonSet,
        starts: List<LocalDate>,
        cycle: Int
    ): (LocalDate) -> Float = { date ->
        val last = starts.lastOrNull { !it.isAfter(date) } ?: starts.firstOrNull()
        hueFor(date, last, cycle, KilnMoodInfluence.hueShift(records, buttons, starts, cycle, date))
    }

    fun bucketToday(records: List<KilnDayRecord>, buttons: KilnButtonSet, today: LocalDate): Int {
        val starts = KilnCyclePredictor.periodStarts(records, buttons)
        val cycle = KilnCyclePredictor.avgCycleLength(starts)
        return bucket(lookup(records, buttons, starts, cycle)(today))
    }
}