package com.example.aiapp

import androidx.compose.foundation.Canvas
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.layout.width
import androidx.compose.material3.MaterialTheme
import androidx.compose.runtime.Composable
import androidx.compose.ui.Modifier
import androidx.compose.ui.geometry.Offset
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.StrokeCap
import androidx.compose.ui.unit.dp

/**
 * A chevron, pointing up or down.
 *
 * Drawn rather than set in a font: a chevron from an icon font is one of the glyphs a system font
 * may simply not have, and the reader who gets an empty box instead is never the one who wrote it.
 *
 * One composable for both directions rather than two that differ by a minus sign -- the pair would
 * drift, and the drift would be a bug in exactly one direction.
 *
 * It draws no label of its own, so every caller owes it a `contentDescription`: this is the whole
 * of what assistive technology has to go on, and it is also the answer to "what was that arrow for"
 * six months from now.
 */
@Composable
fun Chevron(
    pointingUp: Boolean,
    modifier: Modifier = Modifier,
    colour: Color = MaterialTheme.colorScheme.onSurfaceVariant,
) {
    Canvas(modifier.width(20.dp).height(10.dp)) {
        val inset = 2.dp.toPx()
        val point = if (pointingUp) inset else size.height - inset
        val ends = if (pointingUp) size.height - inset else inset
        val stroke = 2.dp.toPx()
        drawLine(
            colour,
            Offset(inset, ends),
            Offset(size.width / 2, point),
            strokeWidth = stroke,
            cap = StrokeCap.Round,
        )
        drawLine(
            colour,
            Offset(size.width / 2, point),
            Offset(size.width - inset, ends),
            strokeWidth = stroke,
            cap = StrokeCap.Round,
        )
    }
}