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.items
import androidx.compose.foundation.shape.RoundedCornerShape
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.automirrored.filled.ArrowBack
import androidx.compose.material.icons.automirrored.filled.ArrowForwardIos
import androidx.compose.material.icons.filled.Add
import androidx.compose.material.icons.filled.Delete
import androidx.compose.material.icons.filled.Edit
import androidx.compose.material.icons.filled.MoreVert
import androidx.compose.material.icons.filled.MusicNote
import androidx.compose.material.icons.filled.PlayArrow
import androidx.compose.material.icons.filled.PlaylistAdd
import androidx.compose.material.icons.filled.QueueMusic
import androidx.compose.material.icons.filled.Shuffle
import androidx.compose.material.icons.filled.Videocam
import androidx.compose.material3.AlertDialog
import androidx.compose.material3.Button
import androidx.compose.material3.ButtonDefaults
import androidx.compose.material3.DropdownMenu
import androidx.compose.material3.DropdownMenuItem
import androidx.compose.material3.Icon
import androidx.compose.material3.IconButton
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.OutlinedTextField
import androidx.compose.material3.OutlinedTextFieldDefaults
import androidx.compose.material3.Surface
import androidx.compose.material3.Text
import androidx.compose.material3.TextButton
import androidx.compose.runtime.Composable
import androidx.compose.runtime.collectAsState
import androidx.compose.runtime.getValue
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.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.unit.dp
import androidx.compose.ui.unit.sp
import androidx.media3.common.util.UnstableApi
import com.example.data.db.PlaylistEntity
import com.example.data.model.MediaItemData
import com.example.playback.PlaybackManager
import com.example.ui.theme.AccentViolet
import com.example.ui.theme.AmoledBlack
import com.example.ui.theme.DividerSubtle
import com.example.ui.theme.ErrorRed
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 PlaylistsScreen(
  viewModel: MainViewModel,
  onCreatePlaylistClick: () -> Unit,
  onPlayMedia: (MediaItemData) -> Unit,
  modifier: Modifier = Modifier
) {
  val playlists by viewModel.playlists.collectAsState()
  val selectedPlaylistId by viewModel.selectedPlaylistId.collectAsState()
  val playlistItems by viewModel.playlistItems.collectAsState()
  val allMedia by viewModel.allMedia.collectAsState()

  var renameTarget by remember { mutableStateOf<PlaylistEntity?>(null) }
  var deleteTarget by remember { mutableStateOf<PlaylistEntity?>(null) }

  Column(
    modifier = modifier
      .fillMaxSize()
      .background(AmoledBlack)
      .statusBarsPadding()
      .testTag("playlists_screen")
  ) {
    if (selectedPlaylistId == null) {
      // Playlists List
      Row(
        modifier = Modifier
          .fillMaxWidth()
          .padding(horizontal = 16.dp, vertical = 12.dp),
        verticalAlignment = Alignment.CenterVertically,
        horizontalArrangement = Arrangement.SpaceBetween
      ) {
        Text(
          text = "Playlists",
          color = TextPrimary,
          style = MaterialTheme.typography.headlineMedium,
          fontWeight = FontWeight.Bold
        )

        IconButton(
          onClick = onCreatePlaylistClick,
          modifier = Modifier.testTag("playlists_create_btn")
        ) {
          Icon(imageVector = Icons.Default.Add, contentDescription = "Create Playlist", tint = AccentViolet)
        }
      }

      if (playlists.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(
              text = "No playlists created yet.",
              color = TextSecondary,
              style = MaterialTheme.typography.bodyMedium
            )
            Spacer(modifier = Modifier.height(16.dp))
            Button(
              onClick = onCreatePlaylistClick,
              colors = ButtonDefaults.buttonColors(containerColor = AccentViolet)
            ) {
              Text("Create Playlist", color = Color.Black, fontWeight = FontWeight.Bold)
            }
          }
        }
      } else {
        LazyColumn(
          modifier = Modifier
            .fillMaxSize()
            .padding(horizontal = 16.dp),
          verticalArrangement = Arrangement.spacedBy(10.dp)
        ) {
          items(playlists, key = { it.playlistId }) { playlist ->
            var showMenu by remember { mutableStateOf(false) }

            Surface(
              modifier = Modifier
                .fillMaxWidth()
                .clip(RoundedCornerShape(12.dp))
                .clickable { viewModel.selectPlaylist(playlist.playlistId) }
                .testTag("playlist_item_${playlist.playlistId}"),
              color = SurfaceSecondary
            ) {
              Row(
                modifier = Modifier.padding(14.dp),
                verticalAlignment = Alignment.CenterVertically
              ) {
                Box(
                  modifier = Modifier
                    .size(46.dp)
                    .clip(RoundedCornerShape(10.dp))
                    .background(SurfaceElevated),
                  contentAlignment = Alignment.Center
                ) {
                  Icon(
                    imageVector = Icons.Default.QueueMusic,
                    contentDescription = null,
                    tint = AccentViolet,
                    modifier = Modifier.size(26.dp)
                  )
                }

                Spacer(modifier = Modifier.width(14.dp))

                Column(modifier = Modifier.weight(1f)) {
                  Text(
                    text = playlist.name,
                    color = TextPrimary,
                    fontSize = 15.sp,
                    fontWeight = FontWeight.SemiBold
                  )
                  Text(
                    text = "Tap to open",
                    color = TextSecondary,
                    fontSize = 12.sp
                  )
                }

                Box {
                  IconButton(onClick = { showMenu = true }) {
                    Icon(imageVector = Icons.Default.MoreVert, contentDescription = null, tint = TextSecondary)
                  }
                  DropdownMenu(
                    expanded = showMenu,
                    onDismissRequest = { showMenu = false },
                    modifier = Modifier.background(SurfaceElevated)
                  ) {
                    DropdownMenuItem(
                      text = { Text("Rename", color = TextPrimary) },
                      onClick = {
                        renameTarget = playlist
                        showMenu = false
                      }
                    )
                    DropdownMenuItem(
                      text = { Text("Delete", color = ErrorRed) },
                      onClick = {
                        deleteTarget = playlist
                        showMenu = false
                      }
                    )
                  }
                }
              }
            }
          }
        }
      }
    } else {
      // Selected Playlist Detail
      val activePlaylist = playlists.find { it.playlistId == selectedPlaylistId }
      val matchingMedia = playlistItems.mapNotNull { item ->
        allMedia.find { it.contentUri == item.mediaUri } ?: MediaItemData(
          id = "pl_${item.id}",
          contentUri = item.mediaUri,
          title = item.title,
          artist = item.artist,
          album = item.album,
          durationMs = item.durationMs,
          isVideo = item.isVideo
        )
      }

      Row(
        modifier = Modifier
          .fillMaxWidth()
          .padding(horizontal = 16.dp, vertical = 10.dp),
        verticalAlignment = Alignment.CenterVertically
      ) {
        IconButton(
          onClick = { viewModel.selectPlaylist(null) },
          modifier = Modifier.testTag("playlist_detail_back_btn")
        ) {
          Icon(imageVector = Icons.AutoMirrored.Filled.ArrowBack, contentDescription = "Back", tint = TextPrimary)
        }
        Text(
          text = activePlaylist?.name ?: "Playlist",
          color = TextPrimary,
          style = MaterialTheme.typography.headlineSmall,
          fontWeight = FontWeight.Bold,
          modifier = Modifier.weight(1f)
        )
      }

      if (matchingMedia.isNotEmpty()) {
        Row(
          modifier = Modifier
            .fillMaxWidth()
            .padding(horizontal = 16.dp, vertical = 8.dp),
          horizontalArrangement = Arrangement.spacedBy(12.dp)
        ) {
          Surface(
            onClick = { PlaybackManager.setQueue(matchingMedia, 0, autoPlay = true) },
            shape = RoundedCornerShape(10.dp),
            color = AccentViolet,
            modifier = Modifier.weight(1f)
          ) {
            Row(
              modifier = Modifier.padding(vertical = 10.dp),
              horizontalArrangement = Arrangement.Center,
              verticalAlignment = Alignment.CenterVertically
            ) {
              Icon(imageVector = Icons.Default.PlayArrow, contentDescription = null, tint = AmoledBlack)
              Spacer(modifier = Modifier.width(6.dp))
              Text("Play All (${matchingMedia.size})", color = AmoledBlack, fontWeight = FontWeight.Bold)
            }
          }

          Surface(
            onClick = {
              PlaybackManager.toggleShuffle()
              PlaybackManager.setQueue(matchingMedia.shuffled(), 0, autoPlay = true)
            },
            shape = RoundedCornerShape(10.dp),
            color = SurfaceElevated,
            modifier = Modifier.weight(1f)
          ) {
            Row(
              modifier = Modifier.padding(vertical = 10.dp),
              horizontalArrangement = Arrangement.Center,
              verticalAlignment = Alignment.CenterVertically
            ) {
              Icon(imageVector = Icons.Default.Shuffle, contentDescription = null, tint = AccentViolet)
              Spacer(modifier = Modifier.width(6.dp))
              Text("Shuffle", color = TextPrimary, fontWeight = FontWeight.Bold)
            }
          }
        }
      }

      if (matchingMedia.isEmpty()) {
        Box(modifier = Modifier.fillMaxSize(), contentAlignment = Alignment.Center) {
          Text("Playlist is empty. Add songs from your library.", color = TextSecondary)
        }
      } else {
        LazyColumn(modifier = Modifier.fillMaxSize()) {
          items(matchingMedia, key = { it.contentUri }) { item ->
            Row(
              modifier = Modifier
                .fillMaxWidth()
                .clickable { onPlayMedia(item) }
                .padding(horizontal = 16.dp, vertical = 10.dp),
              verticalAlignment = Alignment.CenterVertically
            ) {
              Icon(
                imageVector = if (item.isVideo) Icons.Default.Videocam else Icons.Default.MusicNote,
                contentDescription = null,
                tint = AccentViolet,
                modifier = Modifier.size(24.dp)
              )
              Spacer(modifier = Modifier.width(14.dp))
              Column(modifier = Modifier.weight(1f)) {
                Text(text = item.title, color = TextPrimary, fontSize = 14.sp, fontWeight = FontWeight.Medium)
                Text(text = "${item.artist} • ${item.formattedDuration}", color = TextSecondary, fontSize = 12.sp)
              }
              IconButton(
                onClick = { viewModel.removeFromPlaylist(selectedPlaylistId!!, item.contentUri) }
              ) {
                Icon(imageVector = Icons.Default.Delete, contentDescription = "Remove", tint = TextSecondary)
              }
            }
          }
        }
      }
    }
  }

  // Rename Dialog
  renameTarget?.let { pl ->
    var newName by remember { mutableStateOf(pl.name) }
    AlertDialog(
      onDismissRequest = { renameTarget = null },
      confirmButton = {
        Button(
          onClick = {
            viewModel.renamePlaylist(pl.playlistId, newName)
            renameTarget = null
          },
          colors = ButtonDefaults.buttonColors(containerColor = AccentViolet)
        ) {
          Text("Save", color = Color.Black, fontWeight = FontWeight.Bold)
        }
      },
      dismissButton = {
        TextButton(onClick = { renameTarget = null }) { Text("Cancel", color = TextSecondary) }
      },
      title = { Text("Rename Playlist", color = TextPrimary) },
      text = {
        OutlinedTextField(
          value = newName,
          onValueChange = { newName = it },
          singleLine = true,
          colors = OutlinedTextFieldDefaults.colors(
            focusedBorderColor = AccentViolet,
            unfocusedBorderColor = DividerSubtle,
            focusedTextColor = TextPrimary,
            unfocusedTextColor = TextPrimary
          )
        )
      },
      containerColor = SurfaceElevated
    )
  }

  // Delete Confirmation Dialog
  deleteTarget?.let { pl ->
    AlertDialog(
      onDismissRequest = { deleteTarget = null },
      confirmButton = {
        Button(
          onClick = {
            viewModel.deletePlaylist(pl.playlistId)
            deleteTarget = null
          },
          colors = ButtonDefaults.buttonColors(containerColor = ErrorRed)
        ) {
          Text("Delete", color = Color.White)
        }
      },
      dismissButton = {
        TextButton(onClick = { deleteTarget = null }) { Text("Cancel", color = TextSecondary) }
      },
      title = { Text("Delete Playlist?", color = TextPrimary) },
      text = {
        Text(
          "Are you sure you want to delete \"${pl.name}\"? Your original media files will NOT be deleted.",
          color = TextSecondary
        )
      },
      containerColor = SurfaceElevated
    )
  }
}