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.Folder
import androidx.compose.material.icons.filled.MusicNote
import androidx.compose.material.icons.filled.PlayArrow
import androidx.compose.material.icons.filled.Videocam
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.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.model.MediaItemData
import com.example.playback.PlaybackManager
import com.example.ui.theme.AccentViolet
import com.example.ui.theme.AmoledBlack
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 FoldersScreen(
  viewModel: MainViewModel,
  onPlayMedia: (MediaItemData) -> Unit,
  modifier: Modifier = Modifier
) {
  val allMedia by viewModel.allMedia.collectAsState()
  val activeFolder by viewModel.activeFolder.collectAsState()

  val foldersMap = allMedia.groupBy { it.folderName }

  Column(
    modifier = modifier
      .fillMaxSize()
      .background(AmoledBlack)
      .statusBarsPadding()
      .testTag("folders_screen")
  ) {
    // Header
    Row(
      modifier = Modifier
        .fillMaxWidth()
        .padding(horizontal = 16.dp, vertical = 12.dp),
      verticalAlignment = Alignment.CenterVertically
    ) {
      if (activeFolder != null) {
        IconButton(
          onClick = { viewModel.setActiveFolder(null) },
          modifier = Modifier.testTag("folder_back_btn")
        ) {
          Icon(
            imageVector = Icons.AutoMirrored.Filled.ArrowBack,
            contentDescription = "Back to Folders",
            tint = TextPrimary
          )
        }
      }

      Text(
        text = activeFolder ?: "Media Folders",
        color = TextPrimary,
        style = MaterialTheme.typography.headlineMedium,
        fontWeight = FontWeight.Bold
      )
    }

    if (activeFolder == null) {
      // List of Folders
      if (foldersMap.isEmpty()) {
        Box(modifier = Modifier.fillMaxSize(), contentAlignment = Alignment.Center) {
          Text("No media folders detected.", color = TextSecondary)
        }
      } else {
        LazyColumn(
          modifier = Modifier
            .fillMaxSize()
            .padding(horizontal = 16.dp),
          verticalArrangement = Arrangement.spacedBy(10.dp)
        ) {
          foldersMap.forEach { (folderName, items) ->
            item(key = folderName) {
              val audioCount = items.count { !it.isVideo }
              val videoCount = items.count { it.isVideo }

              Surface(
                modifier = Modifier
                  .fillMaxWidth()
                  .clip(RoundedCornerShape(12.dp))
                  .clickable { viewModel.setActiveFolder(folderName) },
                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.Folder,
                      contentDescription = null,
                      tint = AccentViolet,
                      modifier = Modifier.size(26.dp)
                    )
                  }

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

                  Column(modifier = Modifier.weight(1f)) {
                    Text(
                      text = folderName,
                      color = TextPrimary,
                      fontSize = 15.sp,
                      fontWeight = FontWeight.SemiBold
                    )
                    Spacer(modifier = Modifier.height(2.dp))
                    Text(
                      text = "${items.size} files • $audioCount audio, $videoCount video",
                      color = TextSecondary,
                      fontSize = 12.sp
                    )
                  }

                  Icon(
                    imageVector = Icons.AutoMirrored.Filled.ArrowForwardIos,
                    contentDescription = null,
                    tint = TextSecondary,
                    modifier = Modifier.size(16.dp)
                  )
                }
              }
            }
          }
        }
      }
    } else {
      // Media inside active folder
      val folderItems = foldersMap[activeFolder] ?: emptyList()

      Row(
        modifier = Modifier
          .fillMaxWidth()
          .padding(horizontal = 16.dp, vertical = 6.dp),
        horizontalArrangement = Arrangement.SpaceBetween,
        verticalAlignment = Alignment.CenterVertically
      ) {
        Text("${folderItems.size} files", color = TextSecondary, fontSize = 13.sp)

        Surface(
          onClick = {
            if (folderItems.isNotEmpty()) {
              PlaybackManager.setQueue(folderItems, 0, autoPlay = true)
            }
          },
          shape = RoundedCornerShape(8.dp),
          color = AccentViolet
        ) {
          Row(
            modifier = Modifier.padding(horizontal = 10.dp, vertical = 6.dp),
            verticalAlignment = Alignment.CenterVertically
          ) {
            Icon(imageVector = Icons.Default.PlayArrow, contentDescription = null, tint = AmoledBlack, modifier = Modifier.size(16.dp))
            Spacer(modifier = Modifier.width(4.dp))
            Text("Play Folder", color = AmoledBlack, fontWeight = FontWeight.Bold, fontSize = 12.sp)
          }
        }
      }

      LazyColumn(modifier = Modifier.fillMaxSize()) {
        items(folderItems, key = { it.id }) { 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.formattedDuration} • ${item.formattedSize}",
                color = TextSecondary,
                fontSize = 12.sp
              )
            }
            IconButton(onClick = { onPlayMedia(item) }) {
              Icon(imageVector = Icons.Default.PlayArrow, contentDescription = "Play", tint = TextPrimary)
            }
          }
        }
      }
    }
  }
}