/* 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.sessioncontrol.viewholders.onboarding

import android.content.Context
import android.graphics.Canvas
import android.graphics.Paint
import android.text.SpannableString
import android.text.Spanned
import android.text.style.ImageSpan
import android.view.View
import androidx.annotation.DrawableRes
import androidx.appcompat.content.res.AppCompatResources
import androidx.recyclerview.widget.RecyclerView
import kotlinx.android.synthetic.main.onboarding_private_browsing.view.*
import org.mozilla.fenix.R
import org.mozilla.fenix.ext.setBounds

class OnboardingPrivateBrowsingViewHolder(view: View) : RecyclerView.ViewHolder(view) {

    init {
        view.header_text.setOnboardingIcon(R.drawable.ic_onboarding_private_browsing)

        // Display a private browsing icon as a character inside the description text.
        val inlineIcon = PrivateBrowsingImageSpan(
            view.context,
            R.drawable.ic_private_browsing,
            view.description_text.lineHeight
        )

        val text = SpannableString(view.context.getString(R.string.onboarding_private_browsing_description)).apply {
            val spanStartIndex = indexOf(IMAGE_PLACEHOLDER)
            setSpan(
                    inlineIcon,
                spanStartIndex,
                spanStartIndex + IMAGE_PLACEHOLDER.length,
                Spanned.SPAN_EXCLUSIVE_EXCLUSIVE
            )
        }

        view.description_text.text = text
    }

    class PrivateBrowsingImageSpan(
        context: Context,
        @DrawableRes drawableId: Int,
        size: Int
    ) : ImageSpan(
        AppCompatResources.getDrawable(context, drawableId)!!.apply { setBounds(size) }
    ) {
        override fun draw(
            canvas: Canvas,
            text: CharSequence?,
            start: Int,
            end: Int,
            x: Float,
            top: Int,
            y: Int,
            bottom: Int,
            paint: Paint
        ) {
            canvas.save()
            val fmPaint = paint.fontMetricsInt
            val fontHeight = fmPaint.descent - fmPaint.ascent
            val centerY = y + fmPaint.descent - fontHeight / 2
            val transY = (centerY - (drawable.bounds.bottom - drawable.bounds.top) / 2).toFloat()
            canvas.translate(x, transY)
            drawable.draw(canvas)
            canvas.restore()
        }
    }

    companion object {
        const val IMAGE_PLACEHOLDER = "%s"
        const val LAYOUT_ID = R.layout.onboarding_private_browsing
    }
}