package com.example.ui.screens

import androidx.compose.foundation.background
import androidx.compose.foundation.clickable
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.Spacer
import androidx.compose.foundation.layout.fillMaxSize
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.layout.statusBarsPadding
import androidx.compose.foundation.layout.width
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.foundation.lazy.itemsIndexed
import androidx.compose.foundation.shape.RoundedCornerShape
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.filled.ClearAll
import androidx.compose.material.icons.filled.Delete
import androidx.compose.material.icons.filled.KeyboardArrowDown
import androidx.compose.material.icons.filled.KeyboardArrowUp
import androidx.compose.material.icons.filled.MusicNote
import androidx.compose.material.icons.filled.PlayArrow
import androidx.compose.material.icons.filled.QueueMusic
import androidx.compose.material.icons.filled.Repeat
import androidx.compose.material.icons.filled.RepeatOne
import androidx.compose.material.icons.filled.Shuffle
import androidx.compose.material.icons.filled.Videocam
import androidx.compose.material3.Button
import androidx.compose.material3.ButtonDefaults
import androidx.compose.material3.Icon
import androidx.compose.material3.IconButton
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.Surface
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.collectAsState
import androidx.compose.runtime.getValue
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.platform.testTag
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.sp
import androidx.media3.common.util.UnstableApi
import com.example.data.model.MediaItemData
import com.example.data.model.RepeatMode
import com.example.playback.PlaybackManager
import com.example.ui.theme.AccentViolet
import com.example.ui.theme.AccentVioletDim
import com.example.ui.theme.AmoledBlack
import com.example.ui.theme.DividerSubtle
import com.example.ui.theme.SurfaceElevated
import com.example.ui.theme.SurfaceSecondary
import com.example.ui.theme.TextPrimary
import com.example.ui.theme.TextSecondary
import com.example.ui.viewmodel.MainViewModel

@OptIn(UnstableApi::class)
@Composable
fun QueueScreen(
  viewModel: MainViewModel,
  onPlayQueueItem: (MediaItemData) -> Unit,
  modifier: Modifier = Modifier
) {
  val queue by PlaybackManager.queue.collectAsState()
  val queueIndex by PlaybackManager.queueIndex.collectAsState()
  val currentItem by PlaybackManager.currentMediaItem.collectAsState()
  val isShuffle by PlaybackManager.isShuffleEnabled.collectAsState()
  val repeatMode by PlaybackManager.repeatMode.collectAsState()

  Column(
    modifier = modifier
      .fillMaxSize()
      .background(AmoledBlack)
      .statusBarsPadding()
      .testTag("queue_screen")
  ) {
    // Header
    Row(
      modifier = Modifier
        .fillMaxWidth()
        .padding(horizontal = 16.dp, vertical = 12.dp),
      verticalAlignment = Alignment.CenterVertically,
      horizontalArrangement = Arrangement.SpaceBetween
    ) {
      Column {
        Text(
          text = "Playback Queue",
          color = TextPrimary,
          style = MaterialTheme.typography.headlineMedium,
          fontWeight = FontWeight.Bold
        )
        Text(
          text = "${queue.size} items in queue",
          color = TextSecondary,
          fontSize = 12.sp
        )
      }

      Row(verticalAlignment = Alignment.CenterVertically) {
        IconButton(
          onClick = { PlaybackManager.toggleShuffle() },
          modifier = Modifier.testTag("queue_shuffle_btn")
        ) {
          Icon(
            imageVector = Icons.Default.Shuffle,
            contentDescription = "Shuffle",
            tint = if (isShuffle) AccentViolet else TextSecondary
          )
        }

        IconButton(
          onClick = {
            val next = when (repeatMode) {
              RepeatMode.OFF -> RepeatMode.ALL
              RepeatMode.ALL -> RepeatMode.ONE
              RepeatMode.ONE -> RepeatMode.OFF
            }
            PlaybackManager.setRepeatMode(next)
          },
          modifier = Modifier.testTag("queue_repeat_btn")
        ) {
          Icon(
            imageVector = if (repeatMode == RepeatMode.ONE) Icons.Default.RepeatOne else Icons.Default.Repeat,
            contentDescription = "Repeat Mode",
            tint = if (repeatMode != RepeatMode.OFF) AccentViolet else TextSecondary
          )
        }

        if (queue.isNotEmpty()) {
          IconButton(
            onClick = { PlaybackManager.clearQueue() },
            modifier = Modifier.testTag("queue_clear_btn")
          ) {
            Icon(imageVector = Icons.Default.ClearAll, contentDescription = "Clear Queue", tint = TextSecondary)
          }
        }
      }
    }

    if (queue.isEmpty()) {
      Box(
        modifier = Modifier
          .fillMaxSize()
          .padding(32.dp),
        contentAlignment = Alignment.Center
      ) {
        Column(horizontalAlignment = Alignment.CenterHorizontally) {
          Icon(imageVector = Icons.Default.QueueMusic, contentDescription = null, tint = AccentViolet, modifier = Modifier.size(56.dp))
          Spacer(modifier = Modifier.height(12.dp))
          Text("Queue is empty.", color = TextSecondary)
          Spacer(modifier = Modifier.height(8.dp))
          Text("Add items from your music or video library.", color = TextSecondary, fontSize = 12.sp)
        }
      }
    } else {
      LazyColumn(
        modifier = Modifier
          .fillMaxSize()
          .padding(horizontal = 16.dp),
        verticalArrangement = Arrangement.spacedBy(8.dp)
      ) {
        itemsIndexed(queue, key = { index, item -> "${item.id}_$index" }) { index, item ->
          val isCurrent = index == queueIndex

          Surface(
            modifier = Modifier
              .fillMaxWidth()
              .clip(RoundedCornerShape(12.dp))
              .clickable {
                PlaybackManager.setQueue(queue, index, autoPlay = true)
              }
              .testTag("queue_item_$index"),
            color = if (isCurrent) AccentVioletDim else SurfaceSecondary
          ) {
            Row(
              modifier = Modifier.padding(12.dp),
              verticalAlignment = Alignment.CenterVertically
            ) {
              // Playing indicator or index
              Box(
                modifier = Modifier
                  .size(36.dp)
                  .clip(RoundedCornerShape(8.dp))
                  .background(if (isCurrent) AccentViolet else SurfaceElevated),
                contentAlignment = Alignment.Center
              ) {
                if (isCurrent) {
                  Icon(imageVector = Icons.Default.PlayArrow, contentDescription = "Playing", tint = AmoledBlack, modifier = Modifier.size(20.dp))
                } else {
                  Text(text = "${index + 1}", color = TextSecondary, fontSize = 12.sp, fontWeight = FontWeight.Bold)
                }
              }

              Spacer(modifier = Modifier.width(12.dp))

              Column(modifier = Modifier.weight(1f)) {
                Text(
                  text = item.title,
                  color = if (isCurrent) AccentViolet else TextPrimary,
                  fontSize = 14.sp,
                  fontWeight = if (isCurrent) FontWeight.Bold else FontWeight.Medium,
                  maxLines = 1,
                  overflow = TextOverflow.Ellipsis
                )
                Text(
                  text = "${item.artist} • ${item.formattedDuration}",
                  color = TextSecondary,
                  fontSize = 12.sp,
                  maxLines = 1,
                  overflow = TextOverflow.Ellipsis
                )
              }

              // Reorder Buttons (Move Up / Down)
              if (index > 0) {
                IconButton(
                  onClick = { PlaybackManager.reorderQueue(index, index - 1) },
                  modifier = Modifier.size(32.dp)
                ) {
                  Icon(imageVector = Icons.Default.KeyboardArrowUp, contentDescription = "Move Up", tint = TextSecondary, modifier = Modifier.size(18.dp))
                }
              }

              if (index < queue.lastIndex) {
                IconButton(
                  onClick = { PlaybackManager.reorderQueue(index, index + 1) },
                  modifier = Modifier.size(32.dp)
                ) {
                  Icon(imageVector = Icons.Default.KeyboardArrowDown, contentDescription = "Move Down", tint = TextSecondary, modifier = Modifier.size(18.dp))
                }
              }

              // Remove from Queue
              IconButton(
                onClick = { PlaybackManager.removeFromQueue(index) },
                modifier = Modifier.size(32.dp)
              ) {
                Icon(imageVector = Icons.Default.Delete, contentDescription = "Remove", tint = TextSecondary, modifier = Modifier.size(18.dp))
              }
            }
          }
        }
      }
    }
  }
}