package com.vgmlr.kiln

import androidx.compose.animation.animateColorAsState
import androidx.compose.foundation.background
import androidx.compose.foundation.border
import androidx.compose.foundation.clickable
import androidx.compose.foundation.horizontalScroll
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.size
import androidx.compose.foundation.rememberScrollState
import androidx.compose.foundation.shape.RoundedCornerShape
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.filled.Add
import androidx.compose.material3.Icon
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.LaunchedEffect
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.setValue
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.clip
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.layout.Layout
import androidx.compose.ui.unit.Constraints
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.Spacer
import androidx.compose.foundation.layout.width
import androidx.compose.foundation.shape.CircleShape

private val CHIP_SHAPE = RoundedCornerShape(ROUND_END)
private val CHIP_HEIGHT = 30.dp
private val CHIP_GAP = 10.dp
private const val ROWS = 3
private val PERIOD_DOT = 10.dp
private val PERIOD_DOT_GAP = 6.dp
private val PeriodDot = Color(0xFF880000)

private val SelBg = Color.White.copy(alpha = 0.12f)
private val SelRing = Color.White.copy(alpha = 0.45f)
private val SelFg = Color.White.copy(alpha = 1.0f)
private val IdleBg = Color.White.copy(alpha = 0.05f)
private val IdleRing = CMuted.copy(alpha = 0.30f)
private val IdleFg = Color.White.copy(alpha = 0.85f)

@Composable
internal fun ChipPager(
    buttons: List<KilnButton>,
    checked: Set<Long>,
    onToggle: (Long) -> Unit,
    onAdd: () -> Unit,
    modifier: Modifier = Modifier
) {
    val scroll = rememberScrollState()
    val shown = remember(buttons) { buttons.filter { it.label.isNotBlank() } }
    var centred by remember(shown.size) { mutableStateOf(false) }

    LaunchedEffect(scroll.maxValue, centred) {
        if (centred || scroll.maxValue == Int.MAX_VALUE) return@LaunchedEffect
        scroll.scrollTo(scroll.maxValue / 2)
        centred = true
    }

    ChipRows(modifier.fillMaxWidth().horizontalScroll(scroll)) {
        shown.forEach { b ->
            SightingChip(
                b.label,
                b.id in checked,
                b.kindEnum == KilnButtonKind.PERIOD
            ) { onToggle(b.id) }
        }

        AddChip(onAdd)
    }
}

@Composable
private fun ChipRows(modifier: Modifier = Modifier, content: @Composable () -> Unit) {
    Layout(content, modifier) { measurables, constraints ->
        val gap = CHIP_GAP.roundToPx()
        val rowH = CHIP_HEIGHT.roundToPx()
        val chips = measurables.map { it.measure(Constraints()) }
        val base = chips.size / ROWS
        val extra = chips.size % ROWS
        var taken = 0
        val rows = List(ROWS) { r ->
            val n = base + if (r < extra) 1 else 0
            chips.subList(taken, taken + n).also { taken += n }
        }

        val widths = rows.map { r ->
            if (r.isEmpty()) 0 else r.sumOf { it.width } + gap * (r.size - 1)
        }
        val w = (widths.max() + gap * 2).coerceAtLeast(constraints.minWidth)
        val h = rowH * ROWS + gap * (ROWS - 1)

        layout(w, h) {
            var y = 0
            rows.forEachIndexed { i, row ->
                var x = (w - widths[i]) / 2
                for (c in row) {
                    c.place(x, y)
                    x += c.width + gap
                }
                y += rowH + gap
            }
        }
    }
}

@Composable
private fun SightingChip(
    label: String,
    checked: Boolean,
    period: Boolean,
    onToggle: () -> Unit
) {
    val bg by animateColorAsState(if (checked) SelBg else IdleBg, label = "chipBg")
    val ring by animateColorAsState(if (checked) SelRing else IdleRing, label = "chipRing")
    val fg by animateColorAsState(if (checked) SelFg else IdleFg, label = "chipFg")
    Box(
        Modifier.height(CHIP_HEIGHT)
            .clip(CHIP_SHAPE)
            .background(bg)
            .border(1.dp, ring, CHIP_SHAPE)
            .clickable(onClick = onToggle)
            .padding(horizontal = 12.dp),
        contentAlignment = Alignment.Center
    ) {
        Row(verticalAlignment = Alignment.CenterVertically) {
            if (period) {
                Box(Modifier.size(PERIOD_DOT).background(PeriodDot, CircleShape))
                Spacer(Modifier.width(PERIOD_DOT_GAP))
            }
            Text(
                label,
                fontSize = 14.sp,
                letterSpacing = 0.2.sp,
                color = fg
            )
        }
    }
}

@Composable
private fun AddChip(onClick: () -> Unit) {
    Box(
        Modifier.height(CHIP_HEIGHT)
            .clip(CHIP_SHAPE)
            .background(IdleBg)
            .border(1.dp, IdleRing, CHIP_SHAPE)
            .clickable(onClick = onClick)
            .padding(horizontal = 12.dp),
        contentAlignment = Alignment.Center
    ) {
        Icon(Icons.Default.Add, "Edit Buttons", Modifier.size(16.dp), tint = IdleFg)
    }
}