/*
 * Copyright 2018 Allan Wang
 *
 * 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 ca.allanwang.kau.xml

import android.content.Context
import android.content.res.XmlResourceParser
import android.text.Html
import android.text.Spanned
import androidx.annotation.XmlRes
import ca.allanwang.kau.utils.use
import org.xmlpull.v1.XmlPullParser

/**
 * Created by Allan Wang on 2017-07-30.
 */

/**
 * Parse an xml asynchronously with two tags, <question>Text</question> and <answer>Text</answer>.
 * Note that this should executed in a background thread.
 */
@Suppress("DEPRECATION")
fun Context.kauParseFaq(
    @XmlRes xmlRes: Int,
    /**
     * If \n is used, it will automatically be converted to </br>
     */
    parseNewLine: Boolean = true
): List<FaqItem> {
    val items = mutableListOf<FaqItem>()
    resources.getXml(xmlRes).use { parser: XmlResourceParser ->
        var eventType = parser.eventType
        var question: Spanned? = null
        var flag = -1 // -1, 0, 1 -> invalid, question, answer
        while (eventType != XmlPullParser.END_DOCUMENT) {
            if (eventType == XmlPullParser.START_TAG) {
                flag = when (parser.name) {
                    "question" -> 0
                    "answer" -> 1
                    else -> -1
                }
            } else if (eventType == XmlPullParser.TEXT) {
                when (flag) {
                    0 -> {
                        question = Html.fromHtml(parser.text.replace("\n", if (parseNewLine) "<br/>" else ""))
                        flag = -1
                    }
                    1 -> {
                        items.add(
                            FaqItem(
                                items.size + 1,
                                question
                                    ?: throw IllegalArgumentException("KAU FAQ answer found without a question"),
                                Html.fromHtml(parser.text.replace("\n", if (parseNewLine) "<br/>" else ""))
                            )
                        )
                        question = null
                        flag = -1
                    }
                }
            }
            eventType = parser.next()
        }
    }
    return items
}

data class FaqItem(val number: Int, val question: Spanned, val answer: Spanned)