Favicons.kt

1package com.peachpasswords.ui.components23import android.content.Context4import android.graphics.Bitmap5import android.graphics.BitmapFactory6import com.peachpasswords.shared.extractDomain7import dagger.hilt.android.qualifiers.ApplicationContext8import java.io.File9import java.net.IDN10import java.util.Collections11import java.util.Locale12import java.util.concurrent.ConcurrentHashMap13import java.util.concurrent.TimeUnit14import javax.inject.Inject15import javax.inject.Singleton16import kotlinx.coroutines.CoroutineScope17import kotlinx.coroutines.Dispatchers18import kotlinx.coroutines.SupervisorJob19import kotlinx.coroutines.flow.MutableStateFlow20import kotlinx.coroutines.flow.StateFlow21import kotlinx.coroutines.launch22import kotlinx.coroutines.withContext23import okhttp3.OkHttpClient24import okhttp3.Request2526/**27 * U1: real site favicons, offline-first with a disk cache.28 *29 * Source: DuckDuckGo's icon API (`icons.duckduckgo.com/ip3/{domain}.ico`) —30 * June's explicit choice (2026-08-03), superseding the v2.10.1131 * direct-from-site strategy. One small request per domain; the domain name is32 * the only thing transmitted. Failures negative-cache for [MISS_RETRY_MS] and33 * fall back to initials.34 */35@Singleton36class Favicons @Inject constructor(@ApplicationContext private val context: Context) {3738    private val client: OkHttpClient by lazy {39        OkHttpClient.Builder()40            .connectTimeout(8, TimeUnit.SECONDS)41            .readTimeout(8, TimeUnit.SECONDS)42            .followRedirects(true)43            .build()44    }45    private val dir: File by lazy { File(context.cacheDir, "favicons").apply { mkdirs() } }46    private val fetchDispatcher = Dispatchers.IO.limitedParallelism(2)47    private val scope = CoroutineScope(SupervisorJob() + fetchDispatcher)48    private val inFlight = Collections.newSetFromMap(ConcurrentHashMap<String, Boolean>())4950    /** Bumped whenever any favicon lands on disk; composables key recomposition on it. */51    private val _revision = MutableStateFlow(0)52    val revision: StateFlow<Int> = _revision5354    private fun fileFor(domain: String): File? = faviconCacheFile(dir, domain, ".png")55    private fun missFileFor(domain: String): File? = faviconCacheFile(dir, domain, ".miss")5657    fun bitmap(domain: String, sizePx: Int): Bitmap? = runCatching {58        val file = fileFor(domain) ?: return null59        if (!file.exists()) return null60        val bounds = BitmapFactory.Options().apply { inJustDecodeBounds = true }61        BitmapFactory.decodeFile(file.absolutePath, bounds)62        if (bounds.outWidth <= 0 || bounds.outHeight <= 0) return null63        var sample = 164        while (bounds.outWidth / sample > sizePx * 2 && bounds.outHeight / sample > sizePx * 2) sample *= 265        BitmapFactory.decodeFile(file.absolutePath, BitmapFactory.Options().apply { inSampleSize = sample })66    }.getOrNull()6768    /** Fire-and-forget fetches for every domain missing from the cache. */69    fun prefetch(domains: List<String>) {70        for (domain in domains.mapNotNull(::canonicalFaviconDomain).distinct()) {71            if (!needsFetch(domain) || !inFlight.add(domain)) continue72            scope.launch {73                try {74                    fetch(domain)75                } finally {76                    inFlight.remove(domain)77                }78            }79        }80    }8182    private fun needsFetch(domain: String): Boolean {83        if (fileFor(domain)?.exists() == true) return false84        val miss = missFileFor(domain) ?: return false85        return !miss.exists() || System.currentTimeMillis() - miss.lastModified() >= MISS_RETRY_MS86    }8788    internal suspend fun fetch(domain: String) = withContext(Dispatchers.IO) {89        val canonicalDomain = canonicalFaviconDomain(domain) ?: return@withContext90        val bytes = fetchUrl("https://icons.duckduckgo.com/ip3/$canonicalDomain.ico")91            ?.let(::decodeOrUnwrapIco)92        val target = fileFor(canonicalDomain) ?: return@withContext93        val saved = bytes != null && saveScaledPng(bytes, target)94        if (saved) {95            _revision.value++96        } else {97            runCatching { missFileFor(canonicalDomain)?.createNewFile() }98        }99    }100101    /** GET with a bounded read; returns null on any failure or oversize body. */102    private fun fetchUrl(url: String, maxBytes: Long = MAX_ICON_BYTES): ByteArray? = runCatching {103        val request = Request.Builder().url(url).header("User-Agent", "Peach/1.0").build()104        client.newCall(request).execute().use { response ->105            if (!response.isSuccessful) return@runCatching null106            val body = response.body ?: return@runCatching null107            val source = body.source()108            source.request(maxBytes + 1)109            if (source.buffer.size > maxBytes) null else source.readByteArray()110        }111    }.getOrNull()112113    private fun saveScaledPng(bytes: ByteArray, target: File): Boolean = runCatching {114        val decoded = BitmapFactory.decodeByteArray(bytes, 0, bytes.size) ?: return false115        val scaled = Bitmap.createScaledBitmap(decoded, ICON_PX, ICON_PX, true)116        target.outputStream().use { scaled.compress(Bitmap.CompressFormat.PNG, 100, it) }117        if (scaled !== decoded) scaled.recycle()118        decoded.recycle()119        true120    }.getOrDefault(false)121122    companion object {123        const val ICON_PX = 64124        const val MAX_ICON_BYTES = 256L * 1024L125        const val MISS_RETRY_MS = 7L * 24 * 60 * 60 * 1000126    }127}128129/** Canonical registrable DNS host accepted by the favicon network/cache boundary. */130internal fun canonicalFaviconDomain(raw: String): String? {131    if (raw.isEmpty() || raw != raw.trim()) return null132    if (raw.any { it <= '\u001F' || it == '\u007F' || it in "/\\@?#:" }) return null133    if (raw.endsWith('.')) return null134    val ascii = runCatching { IDN.toASCII(raw, IDN.USE_STD3_ASCII_RULES) }135        .getOrNull()136        ?.lowercase(Locale.ROOT)137        ?: return null138    if (ascii.length > 253 || ascii.split('.').any { it.isEmpty() || it.length > 63 }) return null139    return ascii.takeIf { extractDomain(it) == it }140}141142/** Builds a contained direct-child cache path only after host validation. */143internal fun faviconCacheFile(directory: File, rawDomain: String, suffix: String): File? {144    if (suffix != ".png" && suffix != ".miss") return null145    val domain = canonicalFaviconDomain(rawDomain) ?: return null146    val base = runCatching { directory.canonicalFile }.getOrNull() ?: return null147    val target = runCatching { File(base, "$domain$suffix").canonicalFile }.getOrNull() ?: return null148    return target.takeIf { it.parentFile == base }149}150151/**152 * ICO containers usually wrap a PNG; BitmapFactory sniffs magic bytes and153 * rejects the container. Unwrap the first embedded PNG when present.154 */155internal fun decodeOrUnwrapIco(bytes: ByteArray): ByteArray? {156    if (bytes.size >= 8 && bytes[0] == 0.toByte() && bytes[1] == 0.toByte() &&157        bytes[2] == 1.toByte() && bytes[3] == 0.toByte()158    ) {159        if (bytes.size < 22) return null160        val offset = (bytes[18].toInt() and 0xFF) or161            ((bytes[19].toInt() and 0xFF) shl 8) or162            ((bytes[20].toInt() and 0xFF) shl 16) or163            ((bytes[21].toInt() and 0xFF) shl 24)164        if (offset > 0 && offset + 8 <= bytes.size &&165            bytes[offset] == 0x89.toByte() && bytes[offset + 1] == 0x50.toByte()166        ) {167            return bytes.copyOfRange(offset, bytes.size)168        }169        return null170    }171    return bytes172}