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package com.pitchedapps.frost.web
import android.annotation.SuppressLint
import android.content.Context
import android.webkit.JavascriptInterface
import android.webkit.WebView
import ca.allanwang.kau.utils.gone
import com.pitchedapps.frost.R
import com.pitchedapps.frost.facebook.USER_AGENT_BASIC
import com.pitchedapps.frost.injectors.InjectorContract
import com.pitchedapps.frost.utils.L
import io.reactivex.Single
import io.reactivex.SingleEmitter
import io.reactivex.android.schedulers.AndroidSchedulers
import io.reactivex.schedulers.Schedulers
import org.jetbrains.anko.runOnUiThread
import java.util.concurrent.TimeUnit
/**
* Created by Allan Wang on 2017-08-12.
*
* Launches a headless html request and returns a result pair
* When successful, the pair will contain the html content and -1
* When unsuccessful, the pair will contain an empty string and a StringRes for the given error
*
* All errors are rerouted to success calls, so no exceptions should occur.
* The headless extractor will also destroy itself on cancellation or when the request is finished
*/
fun Context.launchHeadlessHtmlExtractor(url: String, injector: InjectorContract, action: (Single<Pair<String, Int>>) -> Unit) {
val single = Single.create<Pair<String, Int>> { e: SingleEmitter<Pair<String, Int>> ->
val extractor = HeadlessHtmlExtractor(this, url, injector, e)
e.setCancellable {
runOnUiThread { extractor.destroy() }
e.onSuccess("" to R.string.html_extraction_cancelled)
}
}.subscribeOn(AndroidSchedulers.mainThread())
.timeout(20, TimeUnit.SECONDS, Schedulers.io(), { it.onSuccess("" to R.string.html_extraction_timeout) })
.onErrorReturn { "" to R.string.html_extraction_error }
action(single)
}
/**
* Given a link and some javascript, will load the link and load the JS on completion
* The JS is expected to call [HeadlessHtmlExtractor.HtmlJSI.handleHtml], which will be sent
* to the [emitter]
*/
@SuppressLint("ViewConstructor")
private class HeadlessHtmlExtractor(
context: Context, url: String, val injector: InjectorContract, val emitter: SingleEmitter<Pair<String, Int>>
) : WebView(context) {
val startTime = System.currentTimeMillis()
init {
L.v("Created HeadlessHtmlExtractor for $url")
gone()
setupWebview(url)
}
@SuppressLint("SetJavaScriptEnabled")
private fun setupWebview(url: String) {
settings.javaScriptEnabled = true
settings.userAgentString = USER_AGENT_BASIC
webViewClient = HeadlessWebViewClient(url, injector) // basic client that loads our JS once the page has loaded
webChromeClient = QuietChromeClient() // basic client that disables logging
addJavascriptInterface(HtmlJSI(), "Frost")
loadUrl(url)
}
inner class HtmlJSI {
@JavascriptInterface
fun handleHtml(html: String?) {
val time = System.currentTimeMillis() - startTime
emitter.onSuccess((html ?: "") to -1)
post {
L.d("HeadlessHtmlExtractor fetched $url in $time ms")
settings.javaScriptEnabled = false
settings.blockNetworkLoads = true
destroy()
}
}
}
override fun destroy() {
super.destroy()
L.d("HeadlessHtmlExtractor destroyed")
}
}
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