package com.pitchedapps.frost.web

import android.animation.ValueAnimator
import android.annotation.SuppressLint
import android.content.Context
import android.support.v4.view.MotionEventCompat
import android.support.v4.view.NestedScrollingChild
import android.support.v4.view.NestedScrollingChildHelper
import android.support.v4.view.ViewCompat
import android.util.AttributeSet
import android.view.MotionEvent
import android.view.View
import android.view.animation.DecelerateInterpolator
import android.webkit.WebView
import com.pitchedapps.frost.utils.L
import io.reactivex.Scheduler
import io.reactivex.android.schedulers.AndroidSchedulers
import io.reactivex.disposables.Disposable
import io.reactivex.subjects.BehaviorSubject

/**
 * Created by Allan Wang on 2017-05-29.
 *
 * Courtesy of takahirom
 *
 * https://github.com/takahirom/webview-in-coordinatorlayout/blob/master/app/src/main/java/com/github/takahirom/webview_in_coodinator_layout/NestedWebView.java
 */
class FrostWebViewCore @JvmOverloads constructor(
        context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0
) : WebView(context, attrs, defStyleAttr), NestedScrollingChild {

    private val childHelper = NestedScrollingChildHelper(this)
    private var lastY: Int = 0
    private val scrollOffset = IntArray(2)
    private val scrollConsumed = IntArray(2)
    private var nestedOffsetY: Int = 0
    val progressObservable: BehaviorSubject<Int>    // Keeps track of every progress change
    val refreshObservable: BehaviorSubject<Boolean> // Only emits on page loads
    val titleObservable: BehaviorSubject<String>    // Only emits on different non http titles

    var baseUrl: String? = null

    init {
        isNestedScrollingEnabled = true
        progressObservable = BehaviorSubject.create<Int>()
        refreshObservable = BehaviorSubject.create<Boolean>()
        titleObservable = BehaviorSubject.create<String>()
        setupWebview()
    }

    @SuppressLint("SetJavaScriptEnabled")
    fun setupWebview() {
        settings.javaScriptEnabled = true
//        settings.domStorageEnabled = true
        setLayerType(View.LAYER_TYPE_HARDWARE, null)
        setWebViewClient(FrostWebViewClient(refreshObservable))
        setWebChromeClient(FrostChromeClient(progressObservable, titleObservable))
    }

    override fun loadUrl(url: String?) {
        if (url != null)
            super.loadUrl(url)
    }

    fun loadBaseUrl() = loadUrl(baseUrl)

    fun addTitleListener(subscriber: (title: String) -> Unit, scheduler: Scheduler = AndroidSchedulers.mainThread()): Disposable
            = titleObservable.observeOn(scheduler).subscribe(subscriber)

    override fun onTouchEvent(ev: MotionEvent): Boolean {
        val event = MotionEvent.obtain(ev)
        val action = MotionEventCompat.getActionMasked(event)
        if (action == MotionEvent.ACTION_DOWN)
            nestedOffsetY = 0
        val eventY = event.y.toInt()
        event.offsetLocation(0f, nestedOffsetY.toFloat())
        val returnValue: Boolean
        when (action) {
            MotionEvent.ACTION_MOVE -> {
                var deltaY = lastY - eventY
                // NestedPreScroll
                if (dispatchNestedPreScroll(0, deltaY, scrollConsumed, scrollOffset)) {
                    deltaY -= scrollConsumed[1]
                    event.offsetLocation(0f, -scrollOffset[1].toFloat())
                    nestedOffsetY += scrollOffset[1]
                }
                lastY = eventY - scrollOffset[1]
                returnValue = super.onTouchEvent(event)
                // NestedScroll
                if (dispatchNestedScroll(0, scrollOffset[1], 0, deltaY, scrollOffset)) {
                    event.offsetLocation(0f, scrollOffset[1].toFloat())
                    nestedOffsetY += scrollOffset[1]
                    lastY -= scrollOffset[1]
                }
            }
            MotionEvent.ACTION_DOWN -> {
                returnValue = super.onTouchEvent(event)
                lastY = eventY
                startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL)
            }
            MotionEvent.ACTION_UP, MotionEvent.ACTION_CANCEL -> {
                returnValue = super.onTouchEvent(event)
                stopNestedScroll()
            }
            else -> return false
        }
        return returnValue
    }

    /**
     * If webview is already at the top, refresh
     * Otherwise scroll to top
     */
    fun scrollOrRefresh() {
        L.d("Scroll or Refresh")
        if (scrollY < 5) reload()
        else scrollToTop()
    }

    fun scrollToTop() {
        if (scrollY > 1000) scrollTo(0, 0)
        else {
            val animator = ValueAnimator.ofInt(scrollY, 0)
            animator.duration = scrollY.toLong()
            animator.interpolator = DecelerateInterpolator()
            animator.addUpdateListener {
                scrollY = it.animatedValue as Int
                invalidate()
            }
        }
    }

    // Nested Scroll implements
    override fun setNestedScrollingEnabled(enabled: Boolean) {
        childHelper.isNestedScrollingEnabled = enabled
    }

    override fun isNestedScrollingEnabled() = childHelper.isNestedScrollingEnabled

    override fun startNestedScroll(axes: Int) = childHelper.startNestedScroll(axes)

    override fun stopNestedScroll() = childHelper.stopNestedScroll()

    override fun hasNestedScrollingParent() = childHelper.hasNestedScrollingParent()

    override fun dispatchNestedScroll(dxConsumed: Int, dyConsumed: Int, dxUnconsumed: Int, dyUnconsumed: Int, offsetInWindow: IntArray?)
            = childHelper.dispatchNestedScroll(dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed, offsetInWindow)

    override fun dispatchNestedPreScroll(dx: Int, dy: Int, consumed: IntArray?, offsetInWindow: IntArray?)
            = childHelper.dispatchNestedPreScroll(dx, dy, consumed, offsetInWindow)

    override fun dispatchNestedFling(velocityX: Float, velocityY: Float, consumed: Boolean)
            = childHelper.dispatchNestedFling(velocityX, velocityY, consumed)

    override fun dispatchNestedPreFling(velocityX: Float, velocityY: Float)
            = childHelper.dispatchNestedPreFling(velocityX, velocityY)

}