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.rememberScrollState
import androidx.compose.foundation.shape.RoundedCornerShape
import androidx.compose.foundation.verticalScroll
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.filled.Animation
import androidx.compose.material.icons.filled.CleaningServices
import androidx.compose.material.icons.filled.CropFree
import androidx.compose.material.icons.filled.Delete
import androidx.compose.material.icons.filled.FilterList
import androidx.compose.material.icons.filled.FitScreen
import androidx.compose.material.icons.filled.Headphones
import androidx.compose.material.icons.filled.History
import androidx.compose.material.icons.filled.Info
import androidx.compose.material.icons.filled.Lock
import androidx.compose.material.icons.filled.Refresh
import androidx.compose.material.icons.filled.Restore
import androidx.compose.material.icons.filled.Speed
import androidx.compose.material3.AlertDialog
import androidx.compose.material3.Button
import androidx.compose.material3.ButtonDefaults
import androidx.compose.material3.Card
import androidx.compose.material3.CardDefaults
import androidx.compose.material3.HorizontalDivider
import androidx.compose.material3.Icon
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.RadioButton
import androidx.compose.material3.RadioButtonDefaults
import androidx.compose.material3.Surface
import androidx.compose.material3.Switch
import androidx.compose.material3.SwitchDefaults
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.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.model.MediaTypeFilter
import com.example.data.model.VideoScaleMode
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 SettingsScreen(
  viewModel: MainViewModel,
  modifier: Modifier = Modifier
) {
  val feedFilter by viewModel.feedFilter.collectAsState()
  val videoScaleMode by viewModel.videoScaleMode.collectAsState()
  val resumePlayback by viewModel.resumePlaybackPref.collectAsState()
  val backgroundAudio by viewModel.backgroundAudioPref.collectAsState()
  val playbackSpeed by viewModel.playbackSpeedPref.collectAsState()
  val reducedMotion by viewModel.reducedMotionPref.collectAsState()

  var showSpeedDialog by remember { mutableStateOf(false) }
  var showFeedFilterDialog by remember { mutableStateOf(false) }
  var showScaleDialog by remember { mutableStateOf(false) }
  var showClearCacheConfirm by remember { mutableStateOf(false) }
  var showPrivacyDialog by remember { mutableStateOf(false) }
  var showAboutDialog by remember { mutableStateOf(false) }

  Column(
    modifier = modifier
      .fillMaxSize()
      .background(AmoledBlack)
      .statusBarsPadding()
      .verticalScroll(rememberScrollState())
      .padding(bottom = 96.dp)
      .testTag("settings_screen")
  ) {
    Text(
      text = "Settings",
      color = TextPrimary,
      style = MaterialTheme.typography.headlineMedium,
      fontWeight = FontWeight.Bold,
      modifier = Modifier.padding(horizontal = 16.dp, vertical = 12.dp)
    )

    // Playback Preferences Section
    SettingsSectionHeader("PLAYBACK")

    SettingsClickableItem(
      title = "Default Feed Filter",
      subtitle = feedFilter.label,
      icon = Icons.Default.FilterList,
      onClick = { showFeedFilterDialog = true },
      testTag = "setting_feed_filter"
    )

    SettingsClickableItem(
      title = "Video Screen Fit Mode",
      subtitle = if (videoScaleMode == VideoScaleMode.FIT) "Fit: Preserve Aspect Ratio (No Crop)" else "Fill: Crop Edges to Fill Screen",
      icon = if (videoScaleMode == VideoScaleMode.FIT) Icons.Default.FitScreen else Icons.Default.CropFree,
      onClick = { showScaleDialog = true },
      testTag = "setting_video_scale"
    )

    SettingsClickableItem(
      title = "Default Playback Speed",
      subtitle = "${playbackSpeed}x",
      icon = Icons.Default.Speed,
      onClick = { showSpeedDialog = true },
      testTag = "setting_playback_speed"
    )

    SettingsSwitchItem(
      title = "Resume Playback",
      subtitle = "Save position and resume unfinished tracks and videos",
      icon = Icons.Default.Restore,
      checked = resumePlayback,
      onCheckedChange = { viewModel.setResumePlayback(it) },
      testTag = "setting_resume_playback"
    )

    SettingsSwitchItem(
      title = "Background Audio",
      subtitle = "Continue playing audio when app is in the background or screen off",
      icon = Icons.Default.Headphones,
      checked = backgroundAudio,
      onCheckedChange = { viewModel.setBackgroundAudio(it) },
      testTag = "setting_background_audio"
    )

    // UI & Accessibility Section
    SettingsSectionHeader("ACCESSIBILITY & UI")

    SettingsSwitchItem(
      title = "Reduced Motion",
      subtitle = "Minimize animations and transitions",
      icon = Icons.Default.Animation,
      checked = reducedMotion,
      onCheckedChange = { viewModel.setReducedMotion(it) },
      testTag = "setting_reduced_motion"
    )

    // Library & Storage Section
    SettingsSectionHeader("LIBRARY & STORAGE")

    SettingsClickableItem(
      title = "Rescan Media Library",
      subtitle = "Scan device storage for new songs and videos",
      icon = Icons.Default.Refresh,
      onClick = { viewModel.scanMedia() },
      testTag = "setting_rescan_media"
    )

    SettingsClickableItem(
      title = "Clear Playback History",
      subtitle = "Clear recent history without touching files",
      icon = Icons.Default.History,
      onClick = { viewModel.clearHistory() },
      testTag = "setting_clear_history"
    )

    SettingsClickableItem(
      title = "Clear App Cache",
      subtitle = "Free temporary thumbnails and image caches",
      icon = Icons.Default.CleaningServices,
      onClick = { showClearCacheConfirm = true },
      testTag = "setting_clear_cache"
    )

    // About Section
    SettingsSectionHeader("ABOUT")

    SettingsClickableItem(
      title = "Privacy Policy",
      subtitle = "100% offline. Zero tracking, telemetry, or remote uploads.",
      icon = Icons.Default.Lock,
      onClick = { showPrivacyDialog = true },
      testTag = "setting_privacy"
    )

    SettingsClickableItem(
      title = "SwipePlay Version",
      subtitle = "Version 1.0.0 (Native Android AMOLED Build)",
      icon = Icons.Default.Info,
      onClick = { showAboutDialog = true },
      testTag = "setting_about"
    )
  }

  // Feed Filter Dialog
  if (showFeedFilterDialog) {
    AlertDialog(
      onDismissRequest = { showFeedFilterDialog = false },
      confirmButton = {
        TextButton(onClick = { showFeedFilterDialog = false }) { Text("Done", color = AccentViolet) }
      },
      title = { Text("Default Feed Filter", color = TextPrimary) },
      text = {
        Column {
          MediaTypeFilter.values().forEach { filter ->
            Row(
              modifier = Modifier
                .fillMaxWidth()
                .clickable {
                  viewModel.setFeedFilter(filter)
                  showFeedFilterDialog = false
                }
                .padding(vertical = 8.dp),
              verticalAlignment = Alignment.CenterVertically
            ) {
              RadioButton(
                selected = feedFilter == filter,
                onClick = {
                  viewModel.setFeedFilter(filter)
                  showFeedFilterDialog = false
                },
                colors = RadioButtonDefaults.colors(selectedColor = AccentViolet)
              )
              Spacer(modifier = Modifier.width(8.dp))
              Text(filter.label, color = TextPrimary)
            }
          }
        }
      },
      containerColor = SurfaceElevated
    )
  }

  // Scale Mode Dialog
  if (showScaleDialog) {
    AlertDialog(
      onDismissRequest = { showScaleDialog = false },
      confirmButton = {
        TextButton(onClick = { showScaleDialog = false }) { Text("Done", color = AccentViolet) }
      },
      title = { Text("Video Scaling Preference", color = TextPrimary) },
      text = {
        Column {
          VideoScaleMode.values().forEach { mode ->
            Row(
              modifier = Modifier
                .fillMaxWidth()
                .clickable {
                  viewModel.setVideoScaleMode(mode)
                  showScaleDialog = false
                }
                .padding(vertical = 8.dp),
              verticalAlignment = Alignment.CenterVertically
            ) {
              RadioButton(
                selected = videoScaleMode == mode,
                onClick = {
                  viewModel.setVideoScaleMode(mode)
                  showScaleDialog = false
                },
                colors = RadioButtonDefaults.colors(selectedColor = AccentViolet)
              )
              Spacer(modifier = Modifier.width(8.dp))
              Column {
                Text(mode.label, color = TextPrimary, fontWeight = FontWeight.SemiBold)
                Text(
                  if (mode == VideoScaleMode.FIT) "Pure black letterboxing, never crop or stretch" else "Crop outer edges to fill window without distortion",
                  color = TextSecondary,
                  fontSize = 11.sp
                )
              }
            }
          }
        }
      },
      containerColor = SurfaceElevated
    )
  }

  // Speed Dialog
  if (showSpeedDialog) {
    val speeds = listOf(0.5f, 0.75f, 1.0f, 1.25f, 1.5f, 1.75f, 2.0f)
    AlertDialog(
      onDismissRequest = { showSpeedDialog = false },
      confirmButton = {
        TextButton(onClick = { showSpeedDialog = false }) { Text("Done", color = AccentViolet) }
      },
      title = { Text("Playback Speed", color = TextPrimary) },
      text = {
        Column {
          speeds.forEach { sp ->
            Row(
              modifier = Modifier
                .fillMaxWidth()
                .clickable {
                  viewModel.setPlaybackSpeed(sp)
                  showSpeedDialog = false
                }
                .padding(vertical = 6.dp),
              verticalAlignment = Alignment.CenterVertically
            ) {
              RadioButton(
                selected = playbackSpeed == sp,
                onClick = {
                  viewModel.setPlaybackSpeed(sp)
                  showSpeedDialog = false
                },
                colors = RadioButtonDefaults.colors(selectedColor = AccentViolet)
              )
              Spacer(modifier = Modifier.width(8.dp))
              Text("${sp}x", color = TextPrimary, fontSize = 14.sp)
            }
          }
        }
      },
      containerColor = SurfaceElevated
    )
  }

  // Clear Cache Dialog
  if (showClearCacheConfirm) {
    AlertDialog(
      onDismissRequest = { showClearCacheConfirm = false },
      confirmButton = {
        Button(
          onClick = {
            viewModel.clearAppCache()
            showClearCacheConfirm = false
          },
          colors = ButtonDefaults.buttonColors(containerColor = AccentViolet)
        ) {
          Text("Clear Cache", color = Color.Black, fontWeight = FontWeight.Bold)
        }
      },
      dismissButton = {
        TextButton(onClick = { showClearCacheConfirm = false }) { Text("Cancel", color = TextSecondary) }
      },
      title = { Text("Clear Temporary Cache?", color = TextPrimary) },
      text = {
        Text("This clears temporary memory and thumbnail caches. Your original audio and video files will NOT be affected.", color = TextSecondary)
      },
      containerColor = SurfaceElevated
    )
  }

  // Privacy Dialog
  if (showPrivacyDialog) {
    AlertDialog(
      onDismissRequest = { showPrivacyDialog = false },
      confirmButton = {
        TextButton(onClick = { showPrivacyDialog = false }) { Text("OK", color = AccentViolet) }
      },
      title = { Text("Offline Privacy Guarantee", color = TextPrimary) },
      text = {
        Text(
          "SwipePlay is completely local and offline. It requests storage permissions strictly to index and play your local audio and video files. It does not connect to external servers, track analytics, show ads, or upload files.",
          color = TextSecondary,
          fontSize = 13.sp
        )
      },
      containerColor = SurfaceElevated
    )
  }

  // About Dialog
  if (showAboutDialog) {
    AlertDialog(
      onDismissRequest = { showAboutDialog = false },
      confirmButton = {
        TextButton(onClick = { showAboutDialog = false }) { Text("Close", color = AccentViolet) }
      },
      title = { Text("SwipePlay", color = TextPrimary, fontWeight = FontWeight.Bold) },
      text = {
        Column {
          Text("A native Android offline music and video player with vertical swipe feed and exact aspect ratio playback.", color = TextSecondary, fontSize = 13.sp)
          Spacer(modifier = Modifier.height(10.dp))
          Text("Powered by AndroidX Media3 ExoPlayer, Jetpack Compose, Room, and Material 3.", color = TextSecondary, fontSize = 12.sp)
        }
      },
      containerColor = SurfaceElevated
    )
  }
}

@Composable
private fun SettingsSectionHeader(title: String) {
  Text(
    text = title,
    color = AccentViolet,
    fontSize = 12.sp,
    fontWeight = FontWeight.Bold,
    letterSpacing = 1.2.sp,
    modifier = Modifier.padding(start = 16.dp, end = 16.dp, top = 20.dp, bottom = 8.dp)
  )
}

@Composable
private fun SettingsClickableItem(
  title: String,
  subtitle: String,
  icon: androidx.compose.ui.graphics.vector.ImageVector,
  onClick: () -> Unit,
  testTag: String
) {
  Row(
    modifier = Modifier
      .fillMaxWidth()
      .clickable { onClick() }
      .padding(horizontal = 16.dp, vertical = 12.dp)
      .testTag(testTag),
    verticalAlignment = Alignment.CenterVertically
  ) {
    Icon(imageVector = icon, contentDescription = null, tint = AccentViolet, modifier = Modifier.size(24.dp))
    Spacer(modifier = Modifier.width(16.dp))
    Column(modifier = Modifier.weight(1f)) {
      Text(text = title, color = TextPrimary, fontSize = 14.sp, fontWeight = FontWeight.Medium)
      Text(text = subtitle, color = TextSecondary, fontSize = 12.sp)
    }
  }
}

@Composable
private fun SettingsSwitchItem(
  title: String,
  subtitle: String,
  icon: androidx.compose.ui.graphics.vector.ImageVector,
  checked: Boolean,
  onCheckedChange: (Boolean) -> Unit,
  testTag: String
) {
  Row(
    modifier = Modifier
      .fillMaxWidth()
      .padding(horizontal = 16.dp, vertical = 10.dp)
      .testTag(testTag),
    verticalAlignment = Alignment.CenterVertically
  ) {
    Icon(imageVector = icon, contentDescription = null, tint = AccentViolet, modifier = Modifier.size(24.dp))
    Spacer(modifier = Modifier.width(16.dp))
    Column(modifier = Modifier.weight(1f)) {
      Text(text = title, color = TextPrimary, fontSize = 14.sp, fontWeight = FontWeight.Medium)
      Text(text = subtitle, color = TextSecondary, fontSize = 12.sp)
    }
    Switch(
      checked = checked,
      onCheckedChange = onCheckedChange,
      colors = SwitchDefaults.colors(
        checkedThumbColor = AmoledBlack,
        checkedTrackColor = AccentViolet,
        uncheckedThumbColor = TextSecondary,
        uncheckedTrackColor = SurfaceElevated
      )
    )
  }
}