package de.wechselbild.wallpaper

import android.app.WallpaperManager
import android.content.Context
import android.graphics.Bitmap
import android.graphics.BitmapFactory
import android.graphics.Canvas
import android.graphics.Color
import android.graphics.Matrix
import android.graphics.Paint
import android.util.Base64
import app.tauri.plugin.JSArray
import app.tauri.plugin.JSObject
import java.io.ByteArrayOutputStream
import java.io.File
import kotlin.random.Random
import org.json.JSONObject

object WallpaperStore {
  private const val PREFS = "wechselbild"
  private const val KEY_INDEX = "current_index"
  private const val CROP_PREFIX = "crop_"
  private data class CropSettings(val mode: String = "cover", val zoom: Double = 1.0, val x: Double = 0.5, val y: Double = 0.5)
  fun directory(context: Context) = File(context.filesDir, "wallpapers").apply { mkdirs() }
  fun files(context: Context) = directory(context).listFiles()?.filter { it.isFile }?.sortedBy { it.name } ?: emptyList()
  private fun prefs(context: Context) = context.getSharedPreferences(PREFS, Context.MODE_PRIVATE)

  fun enabled(context: Context) = prefs(context).getBoolean("enabled", false)
  fun shuffle(context: Context) = prefs(context).getBoolean("shuffle", true)
  fun lockOnly(context: Context) = prefs(context).getBoolean("lockScreenOnly", true)

  fun set(context: Context, name: String, value: Boolean) {
    require(name in setOf("enabled", "shuffle", "lockScreenOnly")) { "Unbekannte Einstellung" }
    prefs(context).edit().putBoolean(name, value).apply()
  }

  fun state(context: Context): JSObject {
    val originals = files(context)
    val index = prefs(context).getInt(KEY_INDEX, 0).coerceIn(0, (originals.size - 1).coerceAtLeast(0))
    val previewFiles = if (index < 24) originals.take(24) else listOf(originals[index]) + originals.take(23)
    val previewIndex = if (index < 24) index else 0
    return JSObject().apply {
      put("imageCount", originals.size)
      put("enabled", enabled(context))
      put("shuffle", shuffle(context))
      put("lockScreenOnly", lockOnly(context))
      put("currentIndex", previewIndex)
      val previews = JSArray()
      previewFiles.forEach { previews.put(thumbnailDataUrl(it)) }
      put("imageUrls", previews)
    }
  }

  fun gallery(context: Context, offset: Int, limit: Int): JSObject {
    val originals = files(context)
    val selectedIndex = prefs(context).getInt(KEY_INDEX, 0).coerceIn(0, (originals.size - 1).coerceAtLeast(0))
    val safeOffset = offset.coerceAtLeast(0).coerceAtMost(originals.size)
    val safeLimit = limit.coerceIn(1, 100)
    val items = JSArray()
    originals.drop(safeOffset).take(safeLimit).forEachIndexed { pageIndex, file ->
      items.put(galleryImage(context, file, safeOffset + pageIndex == selectedIndex))
    }
    return JSObject().apply {
      put("total", originals.size)
      put("items", items)
    }
  }

  private fun cropKey(id: String) = CROP_PREFIX + id

  private fun crop(context: Context, file: File): CropSettings {
    val raw = prefs(context).getString(cropKey(file.name), null) ?: return CropSettings()
    return try {
      val json = JSONObject(raw)
      CropSettings(
        mode = if (json.optString("mode") == "contain") "contain" else "cover",
        zoom = json.optDouble("zoom", 1.0).coerceIn(0.35, 3.0),
        x = json.optDouble("x", 0.5).coerceIn(0.0, 1.0),
        y = json.optDouble("y", 0.5).coerceIn(0.0, 1.0),
      )
    } catch (_: Exception) { CropSettings() }
  }

  private fun galleryImage(context: Context, file: File, selected: Boolean): JSObject {
    val crop = crop(context, file)
    return JSObject().apply {
      put("id", file.name)
      put("url", thumbnailDataUrl(file))
      put("selected", selected)
      put("cropMode", crop.mode)
      put("cropZoom", crop.zoom)
      put("cropPositionX", crop.x)
      put("cropPositionY", crop.y)
    }
  }

  @Synchronized
  fun setCrop(context: Context, id: String, mode: String, zoom: Double, x: Double, y: Double): JSObject? {
    if (id.isBlank() || File(id).name != id) return null
    val file = files(context).firstOrNull { it.name == id } ?: return null
    val normalized = CropSettings(
      mode = if (mode == "contain") "contain" else "cover",
      zoom = zoom.coerceIn(0.35, 3.0),
      x = x.coerceIn(0.0, 1.0),
      y = y.coerceIn(0.0, 1.0),
    )
    val json = JSONObject().apply {
      put("mode", normalized.mode)
      put("zoom", normalized.zoom)
      put("x", normalized.x)
      put("y", normalized.y)
    }
    prefs(context).edit().putString(cropKey(id), json.toString()).apply()
    val selectedIndex = prefs(context).getInt(KEY_INDEX, 0)
    return galleryImage(context, file, files(context).indexOf(file) == selectedIndex)
  }

  @Synchronized
  fun delete(context: Context, id: String): Boolean {
    if (id.isBlank() || File(id).name != id) return false
    val originals = files(context)
    val position = originals.indexOfFirst { it.name == id }
    if (position < 0 || !originals[position].delete()) return false

    val preferences = prefs(context)
    val previousIndex = preferences.getInt(KEY_INDEX, 0).coerceIn(0, (originals.size - 1).coerceAtLeast(0))
    val remaining = originals.size - 1
    val nextIndex = when {
      remaining <= 0 -> 0
      position < previousIndex -> previousIndex - 1
      previousIndex >= remaining -> remaining - 1
      else -> previousIndex
    }
    preferences.edit().remove(cropKey(id)).putInt(KEY_INDEX, nextIndex).apply()
    return true
  }

  private fun renderForScreen(context: Context, source: Bitmap, crop: CropSettings): Bitmap {
    val metrics = context.resources.displayMetrics
    val targetWidth = metrics.widthPixels.coerceAtLeast(1)
    val targetHeight = metrics.heightPixels.coerceAtLeast(1)
    val widthScale = targetWidth.toDouble() / source.width
    val heightScale = targetHeight.toDouble() / source.height
    val baseScale = if (crop.mode == "contain") minOf(widthScale, heightScale) else maxOf(widthScale, heightScale)
    val scale = (baseScale * crop.zoom).toFloat()
    val scaledWidth = source.width * scale
    val scaledHeight = source.height * scale
    val left = ((targetWidth - scaledWidth) * crop.x).toFloat()
    val top = ((targetHeight - scaledHeight) * crop.y).toFloat()

    return Bitmap.createBitmap(targetWidth, targetHeight, Bitmap.Config.ARGB_8888).also { output ->
      val canvas = Canvas(output)
      canvas.drawColor(Color.BLACK)
      val matrix = Matrix().apply {
        setScale(scale, scale)
        postTranslate(left, top)
      }
      canvas.drawBitmap(source, matrix, Paint(Paint.ANTI_ALIAS_FLAG or Paint.FILTER_BITMAP_FLAG))
    }
  }

  private fun decodeForScreen(context: Context, file: File): Bitmap? {
    val bounds = BitmapFactory.Options().apply { inJustDecodeBounds = true }
    BitmapFactory.decodeFile(file.absolutePath, bounds)
    if (bounds.outWidth <= 0 || bounds.outHeight <= 0) return null
    val metrics = context.resources.displayMetrics
    val targetLongSide = maxOf(metrics.widthPixels, metrics.heightPixels).coerceAtLeast(1)
    var sample = 1
    while (maxOf(bounds.outWidth, bounds.outHeight) / (sample * 2) >= targetLongSide) sample *= 2
    return BitmapFactory.decodeFile(file.absolutePath, BitmapFactory.Options().apply {
      inSampleSize = sample
      inPreferredConfig = Bitmap.Config.ARGB_8888
    })
  }

  private fun thumbnailDataUrl(file: File): String {
    val bounds = BitmapFactory.Options().apply { inJustDecodeBounds = true }
    BitmapFactory.decodeFile(file.absolutePath, bounds)
    var sample = 1
    while (bounds.outWidth / sample > 360 || bounds.outHeight / sample > 480) sample *= 2
    val bitmap = BitmapFactory.decodeFile(file.absolutePath, BitmapFactory.Options().apply { inSampleSize = sample }) ?: return ""
    return ByteArrayOutputStream().use { out ->
      bitmap.compress(Bitmap.CompressFormat.JPEG, 76, out)
      bitmap.recycle()
      "data:image/jpeg;base64," + Base64.encodeToString(out.toByteArray(), Base64.NO_WRAP)
    }
  }

  @Synchronized
  fun applyNext(context: Context): Boolean {
    val images = files(context)
    if (images.isEmpty()) return false
    val preferences = prefs(context)
    val previous = preferences.getInt(KEY_INDEX, -1)
    val index = if (shuffle(context) && images.size > 1) {
      generateSequence { Random.nextInt(images.size) }.first { it != previous }
    } else (previous + 1).mod(images.size)
    val bitmap = decodeForScreen(context, images[index]) ?: return false
    val rendered = renderForScreen(context, bitmap, crop(context, images[index]))
    try {
      val manager = WallpaperManager.getInstance(context)
      if (android.os.Build.VERSION.SDK_INT >= 24 && lockOnly(context)) manager.setBitmap(rendered, null, true, WallpaperManager.FLAG_LOCK)
      else manager.setBitmap(rendered)
      preferences.edit().putInt(KEY_INDEX, index).apply()
      return true
    } finally {
      rendered.recycle()
      bitmap.recycle()
    }
  }
}