/*
 * Copyright (C) 2016 - Niklas Baudy, Ruben Gees, Mario Đanić and contributors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.vanniktech.emoji.internal

import android.app.Dialog
import android.content.Context
import android.content.DialogInterface
import android.content.res.ColorStateList
import android.os.Bundle
import android.os.Handler
import android.os.Looper
import android.text.Editable
import android.text.SpannableString
import android.text.TextWatcher
import android.text.style.ForegroundColorSpan
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.EditText
import android.widget.LinearLayout
import android.widget.TextView
import androidx.annotation.Px
import androidx.appcompat.app.AlertDialog
import androidx.core.view.ViewCompat
import androidx.fragment.app.DialogFragment
import androidx.fragment.app.FragmentActivity
import androidx.recyclerview.widget.DiffUtil
import androidx.recyclerview.widget.RecyclerView
import com.vanniktech.emoji.Emoji
import com.vanniktech.emoji.EmojiTextView
import com.vanniktech.emoji.EmojiTheming
import com.vanniktech.emoji.R
import com.vanniktech.emoji.search.SearchEmoji
import com.vanniktech.emoji.search.SearchEmojiResult
import java.util.concurrent.Executors
import java.util.concurrent.ScheduledFuture
import java.util.concurrent.TimeUnit

internal fun interface EmojiSearchDialogDelegate {
  fun onSearchEmojiClick(emoji: Emoji)
}

internal class EmojiSearchDialog : DialogFragment() {
  private var delegate: EmojiSearchDialogDelegate? = null
  private var searchEmoji: SearchEmoji? = null

  private val handler = Handler(Looper.getMainLooper())

  private var future: ScheduledFuture<*>? = null
  private val executorService = Executors.newSingleThreadScheduledExecutor()

  override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
    val activity = requireActivity()
    val dialog = AlertDialog.Builder(activity, theme)
      .setView(R.layout.emoji_dialog_search)
      .show()

    val root = dialog.findViewById<View>(R.id.root)
    val arguments = requireArguments()
    val theming = arguments.parcelable<EmojiTheming>(ARG_THEMING)!!
    root?.setBackgroundColor(theming.backgroundColor)

    val editText = dialog.findViewById<EditText>(R.id.editText)!!
    editText.setTextColor(theming.textColor)
    val secondaryColor = theming.secondaryColor
    editText.setCursorDrawableColor(secondaryColor)
    editText.setHandlesColor(secondaryColor)
    editText.highlightColor = secondaryColor
    ViewCompat.setBackgroundTintList(editText, ColorStateList.valueOf(secondaryColor))

    val recyclerView = dialog.findViewById<MaxHeightSearchRecyclerView>(R.id.recyclerView)
    val adapter = EmojiAdapter(
      theming = theming,
      emojiSearchDialogDelegate = {
        delegate?.onSearchEmojiClick(it)
        dismiss()
      },
    )
    recyclerView?.tint(theming)
    recyclerView?.adapter = adapter

    editText.addTextChangedListener(
      object : TextWatcher {
        override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) = Unit
        override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) = Unit
        override fun afterTextChanged(s: Editable) {
          val query = s.toString()

          future?.cancel(true)
          handler.removeCallbacksAndMessages(null)
          future = executorService.schedule({
            val emojis = searchEmoji?.search(query).orEmpty()
            handler.post {
              adapter.update(emojis, marginStart = null)
            }
          }, 300, TimeUnit.MILLISECONDS,)
        }
      },
    )

    editText.postDelayed({
      editText.showKeyboardAndFocus()
    }, 300L,)

    return dialog
  }

  override fun onDismiss(dialog: DialogInterface) {
    super.onDismiss(dialog)
    future?.cancel(true)
    executorService?.shutdownNow()
    handler.removeCallbacksAndMessages(null)
    delegate = null
  }

  internal companion object {
    private const val TAG = "EmojiSearchDialog"
    private const val ARG_THEMING = "arg-theming"

    fun show(
      context: Context,
      delegate: EmojiSearchDialogDelegate,
      searchEmoji: SearchEmoji,
      theming: EmojiTheming,
    ) {
      EmojiSearchDialog().apply {
        arguments = Bundle(1).apply {
          putParcelable(ARG_THEMING, theming)
        }
        this.delegate = delegate
        this.searchEmoji = searchEmoji
        show((Utils.asActivity(context) as FragmentActivity).supportFragmentManager, TAG)
      }
    }
  }
}

internal class EmojiAdapter(
  private val theming: EmojiTheming,
  private val emojiSearchDialogDelegate: EmojiSearchDialogDelegate?,
) : RecyclerView.Adapter<EmojiViewHolder>() {
  @Px private var marginStart: Int? = null
  private var items = emptyList<SearchEmojiResult>()

  init {
    setHasStableIds(true)
  }

  override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) = EmojiViewHolder(parent)

  override fun onBindViewHolder(holder: EmojiViewHolder, position: Int) {
    val context = holder.textView.context
    val item = items[position]
    holder.textView.setTextColor(theming.textColor) // This is just in case there's a glyph shown.
    holder.textView.text = item.emoji.unicode

    (holder.textView.layoutParams as LinearLayout.LayoutParams).marginStart = marginStart ?: context.resources.getDimensionPixelSize(R.dimen.emoji_search_spacing)

    val shortCode = item.shortcode
    holder.shortCodes.text = SpannableString(shortCode).apply {
      setSpan(ForegroundColorSpan(theming.textSecondaryColor), 0, shortCode.length, 0)
      setSpan(ForegroundColorSpan(theming.secondaryColor), item.range.first, item.range.last + 1, 0)
    }

    holder.itemView.setOnClickListener {
      emojiSearchDialogDelegate?.onSearchEmojiClick(item.emoji)
    }
  }

  override fun getItemCount() = items.size

  fun update(
    new: List<SearchEmojiResult>,
    @Px marginStart: Int?,
  ) {
    val old = ArrayList(items)
    items = new
    this.marginStart = marginStart

    DiffUtil.calculateDiff(DiffUtilHelper(old, items) { it.hashCode() })
      .dispatchUpdatesTo(this)
  }
}

internal class EmojiViewHolder(parent: ViewGroup) : RecyclerView.ViewHolder(LayoutInflater.from(parent.context).inflate(R.layout.emoji_adapter_item_emoji_search, parent, false)) {
  val textView: EmojiTextView by lazy(LazyThreadSafetyMode.NONE) { itemView.findViewById(R.id.textView) }
  val shortCodes: TextView by lazy(LazyThreadSafetyMode.NONE) { itemView.findViewById(R.id.shortCodes) }
}

internal class DiffUtilHelper<T>(
  private val old: List<T>,
  private val new: List<T>,
  private val id: (T) -> Int,
) : DiffUtil.Callback() {
  override fun areItemsTheSame(oldItemPosition: Int, newItemPosition: Int) =
    id(old[oldItemPosition]) == id(new[newItemPosition])

  override fun areContentsTheSame(oldItemPosition: Int, newItemPosition: Int) =
    old[oldItemPosition] == new[newItemPosition]

  override fun getOldListSize() = old.size

  override fun getNewListSize() = new.size
}
