package io.oxygenhub.android.ui.common

import android.graphics.BitmapFactory

import androidx.compose.foundation.Canvas

import androidx.compose.foundation.Image

import androidx.compose.foundation.layout.Box

import androidx.compose.foundation.layout.fillMaxSize

import androidx.compose.foundation.layout.size

import androidx.compose.foundation.shape.CircleShape

import androidx.compose.material3.MaterialTheme

import androidx.compose.material3.Surface

import androidx.compose.material3.Text

import androidx.compose.runtime.Composable

import androidx.compose.runtime.getValue

import androidx.compose.runtime.produceState

import androidx.compose.runtime.remember

import androidx.compose.ui.Alignment

import androidx.compose.ui.Modifier

import androidx.compose.ui.draw.clip

import androidx.compose.ui.geometry.Offset

import androidx.compose.ui.geometry.Size

import androidx.compose.ui.graphics.Color

import androidx.compose.ui.graphics.asImageBitmap

import androidx.compose.ui.layout.ContentScale

import androidx.compose.ui.semantics.contentDescription

import androidx.compose.ui.semantics.semantics

import androidx.compose.ui.unit.Dp

import androidx.compose.ui.unit.dp

import io.oxygenhub.android.api.Avatar

import io.oxygenhub.android.api.HubApi

import kotlinx.coroutines.CancellationException

import java.util.concurrent.ConcurrentHashMap

/** Avatars already fetched this run, by account name: each screen shows the last one at once. */

object Avatars {

    private val known = ConcurrentHashMap<String, Avatar>()

    fun cached(name: String): Avatar? = known[name.lowercase()]

    /** Fetch `name`'s avatar again; on a failure the one fetched before, if any. */

    suspend fun load(api: HubApi, name: String): Avatar? {

        val fresh = try {

            api.avatar(name)

        } catch (e: CancellationException) {

            throw e

        } catch (_: Exception) {

            return cached(name)

        }

        if (fresh == null) known.remove(name.lowercase()) else known[name.lowercase()] = fresh

        return fresh

    }

}

/** `name`'s avatar: the cached one first, then the hub's. */

@Composable

fun rememberAvatar(api: HubApi, name: String): Avatar? {

    val avatar by produceState(Avatars.cached(name), api, name) { value = Avatars.load(api, name) }

    return avatar

}

/**

 * An account's avatar in a circle: its picture, the hub's identicon drawn

 * cell by cell, or its initial while there is neither.

 */

@Composable

fun AvatarImage(avatar: Avatar?, name: String, modifier: Modifier = Modifier, size: Dp = 40.dp) {

    val described = modifier.size(size).clip(CircleShape).semantics { contentDescription = "$name's avatar" }

    when (avatar) {

        is Avatar.Picture -> {

            val bitmap = remember(avatar) {

                BitmapFactory.decodeByteArray(avatar.bytes, 0, avatar.bytes.size)?.asImageBitmap()

            }

            if (bitmap == null) {

                Initial(name, size, described)

            } else {

                Image(bitmap, contentDescription = null, contentScale = ContentScale.Crop, modifier = described)

            }

        }

        is Avatar.Identicon -> Canvas(described) {

            // The hub's 7 by 7 field, so the pattern has the same margin.

            val cell = this.size.width / 7f

            drawRect(Color.hsl(avatar.hue.toFloat(), 0.45f, 0.92f))

            val ink = Color.hsl(avatar.hue.toFloat(), 0.65f, 0.45f)

            for ((x, y) in avatar.cells) {

                drawRect(ink, topLeft = Offset(x * cell, y * cell), size = Size(cell, cell))

            }

        }

        null -> Initial(name, size, described)

    }

}

@Composable

private fun Initial(name: String, size: Dp, modifier: Modifier) {

    Surface(modifier, color = MaterialTheme.colorScheme.primaryContainer) {

        Box(Modifier.fillMaxSize(), contentAlignment = Alignment.Center) {

            Text(

                name.take(1).uppercase(),

                style = if (size >= 56.dp) MaterialTheme.typography.headlineMedium else MaterialTheme.typography.titleMedium,

                color = MaterialTheme.colorScheme.onPrimaryContainer,

            )

        }

    }

}