package org.terst.feedreader.ui

import android.annotation.SuppressLint
import android.content.Intent
import android.net.Uri
import android.webkit.CookieManager
import android.webkit.WebChromeClient
import android.webkit.WebView
import android.webkit.WebViewClient
import androidx.activity.compose.BackHandler
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.padding
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.filled.ArrowBack
import androidx.compose.material.icons.filled.OpenInBrowser
import androidx.compose.material3.ExperimentalMaterial3Api
import androidx.compose.material3.Icon
import androidx.compose.material3.IconButton
import androidx.compose.material3.Scaffold
import androidx.compose.material3.Text
import androidx.compose.material3.TopAppBar
import androidx.compose.runtime.Composable
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.setValue
import androidx.compose.ui.Modifier
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.text.style.TextOverflow
import androidx.compose.ui.viewinterop.AndroidView

/**
 * A real, interactive mini-browser -- JS and DOM storage on, ordinary navigation, no
 * Readability interception. Unlike LinkReaderScreen (always tries to extract a clean
 * article view), this is for the two cases where the user needs to actually USE a
 * page rather than just read it: browsing search results to find an alternate,
 * non-paywalled source for a story, or logging into a site they already subscribe to.
 *
 * Login needs no extra plumbing beyond turning cookies on: Android's CookieManager is
 * a single process-wide store shared by every WebView in the app, so once a session
 * cookie is set here, the reader's (JS-off) extraction WebView picks it up automatically
 * on the next visit to that domain -- same as a normal browser remembering you're signed in.
 */
@SuppressLint("SetJavaScriptEnabled")
@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun BrowserScreen(startUrl: String, onBack: () -> Unit) {
    val context = LocalContext.current
    var title by remember(startUrl) { mutableStateOf<String?>(null) }
    var webViewRef by remember(startUrl) { mutableStateOf<WebView?>(null) }

    // Real browser-style back: step back through THIS WebView's own page history first
    // (search results -> article -> another link -> ...) and only close the screen once
    // there's nowhere left to go back to. An earlier version made back always close the
    // screen outright, on the theory that stepping through a deep session one page at a
    // time was tedious -- but that meant a single back press (system gesture or the in-app
    // arrow) could silently throw away an entire multi-page browsing/login session, which
    // is worse: there's no way to recover it, and it doesn't match how every other browser
    // (or in-app browser view) on the platform behaves. Both the system back gesture and
    // the in-app arrow go through the same path below, so they behave identically.
    fun handleBack() {
        val webView = webViewRef
        if (webView != null && webView.canGoBack()) {
            webView.goBack()
        } else {
            onBack()
        }
    }
    BackHandler(onBack = ::handleBack)

    Scaffold(
        topBar = {
            TopAppBar(
                title = { Text(title ?: "Browser", maxLines = 1, overflow = TextOverflow.Ellipsis) },
                navigationIcon = {
                    IconButton(onClick = ::handleBack) {
                        Icon(Icons.Default.ArrowBack, contentDescription = "Back")
                    }
                },
                actions = {
                    IconButton(onClick = {
                        val url = webViewRef?.url ?: startUrl
                        context.startActivity(Intent(Intent.ACTION_VIEW, Uri.parse(url)))
                    }) {
                        Icon(Icons.Default.OpenInBrowser, contentDescription = "Open in browser")
                    }
                }
            )
        }
    ) { padding ->
        Box(modifier = Modifier.fillMaxSize().padding(padding)) {
            AndroidView(
                modifier = Modifier.fillMaxSize(),
                factory = { ctx ->
                    WebView(ctx).apply {
                        settings.javaScriptEnabled = true
                        settings.domStorageEnabled = true
                        CookieManager.getInstance().setAcceptCookie(true)
                        // Deliberately NOT setAcceptThirdPartyCookies: the login-persistence
                        // feature this screen exists for (see the class doc comment) only
                        // needs a site's own FIRST-party session cookie to reach the
                        // extraction WebView -- third-party cookies are for cross-site
                        // trackers embedded within whatever page is loaded here, which this
                        // feature has no use for and which only adds tracking surface shared
                        // with every other WebView in the app.
                        webViewClient = object : WebViewClient() {
                            override fun onPageFinished(view: WebView, url: String) {
                                title = view.title
                            }
                        }
                        webChromeClient = WebChromeClient()
                        loadUrl(startUrl)
                        webViewRef = this
                    }
                },
                onRelease = { webView ->
                    // Flush explicitly so a just-completed login survives even if the
                    // process is killed shortly after (modern WebView auto-persists, but
                    // this makes it immediate rather than relying on that timing).
                    CookieManager.getInstance().flush()
                    webView.destroy()
                }
            )
        }
    }
}