/* This Source Code Form is subject to the terms of the Mozilla Public
   License, v. 2.0. If a copy of the MPL was not distributed with this
   file, You can obtain one at http://mozilla.org/MPL/2.0/. */

package org.mozilla.fenix.home

import android.content.res.Resources
import android.graphics.drawable.BitmapDrawable
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.constraintlayout.motion.widget.MotionLayout
import androidx.fragment.app.Fragment
import androidx.navigation.Navigation
import kotlinx.android.synthetic.main.fragment_home.view.*
import org.mozilla.fenix.R
import org.mozilla.fenix.ext.requireComponents
import org.mozilla.fenix.home.sessions.SessionsComponent
import org.mozilla.fenix.home.sessions.layoutComponents
import org.mozilla.fenix.mvi.ActionBusFactory
import kotlin.math.roundToInt

class HomeFragment : Fragment() {
    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        val view = inflater.inflate(R.layout.fragment_home, container, false)
        SessionsComponent(view.homeLayout, ActionBusFactory.get(this))
        ActionBusFactory.get(this).logMergedObservables()
        return view
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        layoutComponents(view.homeLayout)

        val searchIcon = requireComponents.search.searchEngineManager.getDefaultSearchEngine(requireContext()).let {
            BitmapDrawable(resources, it.icon)
        }

        // Temporary so we can easily test settings
        view.menuButton.setOnClickListener {
            Navigation.findNavController(it).navigate(R.id.action_homeFragment_to_settingsActivity, null, null)
        }

        view.toolbar.setCompoundDrawablesWithIntrinsicBounds(searchIcon, null, null, null)
        val roundToInt = (toolbarPaddingDp * Resources.getSystem().displayMetrics.density).roundToInt()
        view.toolbar.compoundDrawablePadding = roundToInt
        view.toolbar.setOnClickListener { it ->
            Navigation.findNavController(it).navigate(R.id.action_homeFragment_to_searchFragment, null, null)
        }

        // There is currently an issue with visibility changes in ConstraintLayout 2.0.0-alpha3
        // https://issuetracker.google.com/issues/122090772
        // For now we're going to manually implement KeyTriggers.
        view.homeLayout.setTransitionListener(object : MotionLayout.TransitionListener {
            private val firstKeyTrigger = KeyTrigger(
                firstKeyTriggerFrame,
                { view.toolbar_wrapper.transitionToDark() },
                { view.toolbar_wrapper.transitionToLight() }
            )
            private val secondKeyTrigger = KeyTrigger(
                secondKeyTriggerFrame,
                { view.toolbar_wrapper.transitionToDarkNoBorder() },
                { view.toolbar_wrapper.transitionToDarkFromNoBorder() }
            )

            override fun onTransitionChange(
                motionLayout: MotionLayout?,
                startId: Int,
                endId: Int,
                progress: Float
            ) {
                firstKeyTrigger.conditionallyFire(progress)
                secondKeyTrigger.conditionallyFire(progress)
            }
            override fun onTransitionCompleted(p0: MotionLayout?, p1: Int) { }
        })
    }

    @SuppressWarnings("MagicNumber")
    private class KeyTrigger(
        frame: Int,
        private val onPositiveCross: () -> Unit,
        private val onNegativeCross: () -> Unit
    ) {
        private val fireThreshhold = (frame + 0.5F) / 100.0F
        private var negativeReset = false
        private var positiveReset = false
        private var lastFirePosition = 0f
        private val triggerSlack = 0.1f

        fun conditionallyFire(progress: Float) {
            var offset: Float
            var lastOffset: Float

            if (negativeReset) {
                offset = progress - fireThreshhold
                lastOffset = lastFirePosition - fireThreshhold
                if (offset * lastOffset < 0.0f && offset < 0.0f) {
                    onNegativeCross.invoke()
                    negativeReset = false
                }
            } else if (Math.abs(progress - fireThreshhold) > triggerSlack) {
                negativeReset = true
            }

            if (positiveReset) {
                offset = progress - fireThreshhold
                lastOffset = lastFirePosition - fireThreshhold
                if (offset * lastOffset < 0.0f && offset > 0.0f) {
                    onPositiveCross.invoke()
                    positiveReset = false
                }
            } else if (Math.abs(progress - fireThreshhold) > triggerSlack) {
                positiveReset = true
            }

            lastFirePosition = progress
        }
    }

    companion object {
        const val toolbarPaddingDp = 12f
        const val firstKeyTriggerFrame = 55
        const val secondKeyTriggerFrame = 90
    }
}