package at.lockstep.player.ui

import androidx.compose.foundation.background
import androidx.compose.foundation.gestures.awaitEachGesture
import androidx.compose.foundation.gestures.awaitFirstDown
import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.heightIn
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.foundation.lazy.itemsIndexed
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.automirrored.filled.ArrowBack
import androidx.compose.material3.ExperimentalMaterial3Api
import androidx.compose.material3.Icon
import androidx.compose.material3.IconButton
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.Scaffold
import androidx.compose.material3.Text
import androidx.compose.material3.TopAppBar
import androidx.compose.runtime.Composable
import androidx.compose.runtime.LaunchedEffect
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateListOf
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.input.pointer.pointerInput
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.unit.dp
import at.lockstep.player.LockstepViewModel
import at.lockstep.player.R
import at.lockstep.player.playback.PlaybackService
import at.lockstep.player.util.RunDataStorage

/**
 * Beat taps record [PlaybackService.getPlaybackPositionMs] (Media3 [androidx.media3.common.Player]
 * timeline). JSON is written only when the track changes (skip/prev/next or natural advance) or when
 * the last track in the playlist finishes — see [PlaybackService.trackBoundaryEvents].
 */
@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun AnnotationRoute(
    playlistId: String,
    playback: PlaybackService?,
    viewModel: LockstepViewModel,
    onBack: () -> Unit,
    modifier: Modifier = Modifier,
) {
    val context = LocalContext.current
    var ui by remember {
        mutableStateOf(
            NowPlayingUiState(
                title = context.getString(R.string.now_playing_idle_title),
                artist = context.getString(R.string.now_playing_idle_artist),
                stepFrequencyDisplay = context.getString(R.string.step_frequency_placeholder),
                progress = 0f,
                durationSeconds = 180,
                isPlaying = false,
            ),
        )
    }

    LaunchedEffect(playback) {
        val service = playback ?: return@LaunchedEffect
        service.uiState.collect { p ->
            ui =
                NowPlayingUiState(
                    title = p.title,
                    artist = p.artist,
                    stepFrequencyDisplay = context.getString(R.string.step_frequency_placeholder),
                    progress = p.progress,
                    durationSeconds = p.durationSeconds,
                    isPlaying = p.isPlaying,
                )
        }
    }

    val beatTimesMs = remember { mutableStateListOf<Long>() }
    val annotationSessionFolder = remember { RunDataStorage.newRunSessionFolderName() }

    var playlistDisplayName by remember { mutableStateOf("playlist") }

    LaunchedEffect(playlistId) {
        playlistDisplayName = viewModel.getPlaylistDisplayName(playlistId)
    }

    LaunchedEffect(playback, playlistId, playlistDisplayName, annotationSessionFolder) {
        val service = playback ?: return@LaunchedEffect
        service.trackBoundaryEvents.collect { event ->
            val snapshot = beatTimesMs.toList()
            beatTimesMs.clear()
            viewModel.persistBeatAnnotation(
                playlistId,
                playlistDisplayName,
                annotationSessionFolder,
                event,
                snapshot,
            )
        }
    }

    Scaffold(
        modifier = modifier.fillMaxSize(),
        topBar = {
            TopAppBar(
                title = { Text(text = context.getString(R.string.annotation_title)) },
                navigationIcon = {
                    IconButton(onClick = onBack) {
                        Icon(Icons.AutoMirrored.Filled.ArrowBack, contentDescription = null)
                    }
                },
            )
        },
    ) { padding ->
        Column(
            modifier =
                Modifier
                    .fillMaxSize()
                    .padding(padding),
        ) {
            Text(
                text = context.getString(R.string.annotation_subtitle),
                style = MaterialTheme.typography.bodyMedium,
                color = MaterialTheme.colorScheme.onSurfaceVariant,
                modifier = Modifier.padding(horizontal = 24.dp, vertical = 8.dp),
            )
            Column(
                modifier =
                    Modifier
                        .fillMaxWidth()
                        .heightIn(max = 420.dp)
                        .padding(horizontal = 24.dp),
                verticalArrangement = Arrangement.spacedBy(16.dp),
            ) {
                NowPlayingScreen(
                    state = ui,
                    onProgressChange = { fraction ->
                        playback?.requestSeek(fraction)
                        ui = ui.copy(progress = fraction)
                    },
                    onPrevious = { playback?.requestSkipPrevious() },
                    onTogglePlayPause = { playback?.requestTogglePause() },
                    onNext = { playback?.requestSkipNext() },
                    modifier = Modifier.fillMaxWidth(),
                )
            }
            Text(
                text = context.getString(R.string.annotation_beat_count, beatTimesMs.size),
                style = MaterialTheme.typography.titleMedium,
                modifier = Modifier.padding(horizontal = 24.dp, vertical = 4.dp),
            )
            Box(
                modifier =
                    Modifier
                        .weight(1f)
                        .fillMaxWidth()
                        .padding(horizontal = 16.dp, vertical = 8.dp)
                        .background(MaterialTheme.colorScheme.primaryContainer)
                        .pointerInput(playback) {
                            awaitEachGesture {
                                awaitFirstDown(requireUnconsumed = false)
                                val t = playback?.getPlaybackPositionMs() ?: 0L
                                beatTimesMs.add(t)
                            }
                        },
                contentAlignment = Alignment.Center,
            ) {
                Text(
                    text = context.getString(R.string.annotation_tap_area_label),
                    style = MaterialTheme.typography.headlineSmall,
                    color = MaterialTheme.colorScheme.onPrimaryContainer,
                )
            }
            LazyColumn(
                modifier =
                    Modifier
                        .fillMaxWidth()
                        .heightIn(max = 160.dp)
                        .padding(horizontal = 24.dp, vertical = 8.dp),
                verticalArrangement = Arrangement.spacedBy(4.dp),
            ) {
                itemsIndexed(beatTimesMs) { i, ms ->
                    Row(
                        modifier = Modifier.fillMaxWidth(),
                        horizontalArrangement = Arrangement.SpaceBetween,
                    ) {
                        Text(
                            text = "${i + 1}.",
                            style = MaterialTheme.typography.labelLarge,
                            color = MaterialTheme.colorScheme.onSurfaceVariant,
                        )
                        Text(
                            text = context.getString(R.string.annotation_time_ms, ms.toInt()),
                            style = MaterialTheme.typography.bodyLarge,
                        )
                    }
                }
            }
        }
    }
}