subtracks/app/src/main/kotlin/com/subtracks/ui/library/SongsContent.kt

package com.subtracks.ui.library

import androidx.compose.foundation.clickable
import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.PaddingValues
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.Spacer
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.layout.size
import androidx.compose.foundation.layout.width
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.foundation.lazy.rememberLazyListState
import androidx.compose.foundation.shape.RoundedCornerShape
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.rounded.PlayArrow
import androidx.compose.material3.Icon
import androidx.compose.material3.ListItem
import androidx.compose.material3.ListItemDefaults
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
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.text.font.FontWeight
import androidx.compose.ui.text.style.TextOverflow
import androidx.compose.ui.unit.Dp
import androidx.compose.ui.unit.dp
import androidx.paging.LoadState
import androidx.paging.compose.LazyPagingItems
import androidx.paging.compose.itemKey
import com.subtracks.data.model.CoverArtRef
import com.subtracks.data.model.Song
import com.subtracks.data.model.SongListItem
import com.subtracks.ui.components.CoverArt
import com.subtracks.ui.components.EmptyState
import com.subtracks.ui.components.LoadingState
import com.subtracks.ui.components.rememberViewportFill

@Composable
fun SongsContent(
    items: LazyPagingItems<SongListItem>,
    coverArt: (String?, Boolean) -> CoverArtRef?,
    bottomInset: Dp,
    onSongClick: (Int) -> Unit,
    playingSongId: String? = null,
    modifier: Modifier = Modifier,
) {
    when {
        items.itemCount == 0 && items.loadState.refresh is LoadState.Loading -> {
            LoadingState(modifier)
        }

        items.itemCount == 0 -> {
            EmptyState("No songs yet.", modifier)
        }

        else -> {
            val listState = rememberLazyListState()
            val fill = rememberViewportFill(listState)
            LazyColumn(
                state = listState,
                modifier = modifier.fillMaxSize(),
                contentPadding = PaddingValues(bottom = bottomInset),
            ) {
                items(count = items.itemCount, key = items.itemKey { it.song.id }) { index ->
                    val item = items[index]
                    if (item != null) {
                        SongRow(
                            song = item.song,
                            coverArtId = item.coverArt,
                            coverArt = coverArt,
                            isPlaying = item.song.id == playingSongId,
                            modifier = Modifier.clickable { onSongClick(index) },
                        )
                    }
                }
                item { Spacer(Modifier.height(fill)) }
            }
        }
    }
}

@Composable
fun SongRow(
    song: Song,
    coverArtId: String? = null,
    coverArt: ((String?, Boolean) -> CoverArtRef?)? = null,
    isPlaying: Boolean = false,
    trackNumber: Long? = null,
    trailingContent: (@Composable () -> Unit)? = null,
    modifier: Modifier = Modifier,
) {
    val leadingTrack = trackNumber?.takeIf { coverArt == null }
    ListItem(
        modifier = modifier,
        leadingContent =
            when {
                coverArt != null -> {
                    {
                        CoverArt(
                            ref = coverArt(coverArtId, true),
                            name = song.album ?: song.title,
                            modifier = Modifier.size(48.dp).clip(RoundedCornerShape(6.dp)),
                        )
                    }
                }

                leadingTrack != null -> {
                    { TrackNumber(leadingTrack, isPlaying) }
                }

                else -> {
                    null
                }
            },
        trailingContent = trailingContent,
        headlineContent = {
            Row(
                verticalAlignment = Alignment.CenterVertically,
                horizontalArrangement = Arrangement.spacedBy(8.dp),
            ) {
                if (isPlaying && leadingTrack == null) {
                    Icon(
                        imageVector = Icons.Rounded.PlayArrow,
                        contentDescription = "Playing",
                        tint = MaterialTheme.colorScheme.primary,
                        modifier = Modifier.size(18.dp),
                    )
                }
                Text(
                    text = song.title,
                    color = if (isPlaying) MaterialTheme.colorScheme.primary else Color.Unspecified,
                    fontWeight = if (isPlaying) FontWeight.SemiBold else null,
                    maxLines = 1,
                    overflow = TextOverflow.Ellipsis,
                    modifier = Modifier.weight(1f, fill = false),
                )
            }
        },
        supportingContent = {
            Text(
                text = song.artist.orEmpty().ifEmpty { "\u00A0" },
                color = if (isPlaying) MaterialTheme.colorScheme.primary else MaterialTheme.colorScheme.onSurfaceVariant,
                maxLines = 1,
                overflow = TextOverflow.Ellipsis,
            )
        },
        colors = ListItemDefaults.colors(containerColor = Color.Transparent),
    )
}

@Composable
private fun TrackNumber(
    track: Long,
    isPlaying: Boolean,
) {
    Box(
        modifier = Modifier.width(24.dp),
        contentAlignment = Alignment.CenterStart,
    ) {
        if (isPlaying) {
            Icon(
                imageVector = Icons.Rounded.PlayArrow,
                contentDescription = "Playing",
                tint = MaterialTheme.colorScheme.primary,
                modifier = Modifier.size(18.dp),
            )
        } else {
            Text(
                text = track.toString(),
                style = MaterialTheme.typography.bodyMedium,
                color = MaterialTheme.colorScheme.onSurfaceVariant,
            )
        }
    }
}