Lightning invoice card

app/src/main/java/com/vitorpamplona/amethyst/ui/components/InvoicePreview.kt

@@ -0,0 +1,101 @@
+package com.vitorpamplona.amethyst.ui.components
+
+import android.content.Intent
+import android.net.Uri
+import androidx.compose.foundation.border
+import androidx.compose.foundation.clickable
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.aspectRatio
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material.Button
+import androidx.compose.material.ButtonDefaults
+import androidx.compose.material.Divider
+import androidx.compose.material.Icon
+import androidx.compose.material.MaterialTheme
+import androidx.compose.material.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.res.painterResource
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.unit.sp
+import androidx.core.content.ContextCompat.startActivity
+import com.vitorpamplona.amethyst.R
+
+@Composable
+fun InvoicePreview(lnInvoice: String) {
+  val amount = LnInvoiceUtil.getAmountInSats(lnInvoice)
+
+  val context = LocalContext.current
+
+  Column(modifier = Modifier
+    .fillMaxWidth()
+    .padding(start = 30.dp, end = 30.dp)
+    .clip(shape = RoundedCornerShape(10.dp))
+    .border(1.dp, MaterialTheme.colors.onSurface.copy(alpha = 0.12f), RoundedCornerShape(15.dp))
+  ) {
+
+    Column(
+      modifier = Modifier
+        .fillMaxWidth()
+        .padding(30.dp)
+    ) {
+
+      Row(
+        verticalAlignment = Alignment.CenterVertically,
+        modifier = Modifier
+          .fillMaxWidth()
+          .padding(bottom = 10.dp)
+      ) {
+        Icon(
+          painter = painterResource(R.drawable.lightning),
+          null,
+          modifier = Modifier.size(20.dp),
+          tint = Color.Unspecified
+        )
+
+        Text(
+          text = "Lightning Invoice",
+          fontSize = 20.sp,
+          fontWeight = FontWeight.W500,
+          modifier = Modifier.padding(start = 10.dp)
+        )
+      }
+
+      Divider()
+
+      Text(
+        text = "${amount.toInt()} sats",
+        fontSize = 25.sp,
+        fontWeight = FontWeight.W500,
+        modifier = Modifier
+          .fillMaxWidth()
+          .padding(vertical = 10.dp),
+      )
+
+      Button(
+        modifier = Modifier.fillMaxWidth().padding(vertical = 10.dp),
+        onClick = {
+          runCatching {
+            val intent = Intent(Intent.ACTION_VIEW, Uri.parse("lightning://$lnInvoice"))
+            startActivity(context, intent, null)
+          }
+        },
+        shape = RoundedCornerShape(15.dp),
+        colors = ButtonDefaults.buttonColors(
+          backgroundColor = MaterialTheme.colors.primary
+        )
+      ) {
+        Text(text = "Pay", color = Color.White, fontSize = 20.sp)
+      }
+    }
+  }
+}

app/src/main/java/com/vitorpamplona/amethyst/ui/components/LnInvoiceUtil.kt

@@ -0,0 +1,156 @@
+package com.vitorpamplona.amethyst.ui.components
+
+import java.math.BigDecimal
+import java.util.Locale
+import java.util.regex.Pattern
+
+/** based on litecoinj */
+object LnInvoiceUtil {
+  private val invoicePattern = Pattern.compile("lnbc((?<amount>\\d+)(?<multiplier>[munp])?)?1[^1\\s]+")
+
+  /** The Bech32 character set for encoding.  */
+  private const val CHARSET = "qpzry9x8gf2tvdw0s3jn54khce6mua7l"
+
+  /** The Bech32 character set for decoding.  */
+  private val CHARSET_REV = byteArrayOf(
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+    15, -1, 10, 17, 21, 20, 26, 30, 7, 5, -1, -1, -1, -1, -1, -1,
+    -1, 29, -1, 24, 13, 25, 9, 8, 23, -1, 18, 22, 31, 27, 19, -1,
+    1, 0, 3, 16, 11, 28, 12, 14, 6, 4, 2, -1, -1, -1, -1, -1,
+    -1, 29, -1, 24, 13, 25, 9, 8, 23, -1, 18, 22, 31, 27, 19, -1,
+    1, 0, 3, 16, 11, 28, 12, 14, 6, 4, 2, -1, -1, -1, -1, -1
+  )
+
+
+  /** Find the polynomial with value coefficients mod the generator as 30-bit.  */
+  private fun polymod(values: ByteArray): Int {
+    var c = 1
+    for (v_i in values) {
+      val c0 = c ushr 25 and 0xff
+      c = c and 0x1ffffff shl 5 xor (v_i.toInt() and 0xff)
+      if (c0 and 1 != 0) c = c xor 0x3b6a57b2
+      if (c0 and 2 != 0) c = c xor 0x26508e6d
+      if (c0 and 4 != 0) c = c xor 0x1ea119fa
+      if (c0 and 8 != 0) c = c xor 0x3d4233dd
+      if (c0 and 16 != 0) c = c xor 0x2a1462b3
+    }
+    return c
+  }
+
+  /** Expand a HRP for use in checksum computation.  */
+  private fun expandHrp(hrp: String): ByteArray {
+    val hrpLength = hrp.length
+    val ret = ByteArray(hrpLength * 2 + 1)
+    for (i in 0 until hrpLength) {
+      val c = hrp[i].code and 0x7f // Limit to standard 7-bit ASCII
+      ret[i] = (c ushr 5 and 0x07).toByte()
+      ret[i + hrpLength + 1] = (c and 0x1f).toByte()
+    }
+    ret[hrpLength] = 0
+    return ret
+  }
+
+  /** Verify a checksum.  */
+  private fun verifyChecksum(hrp: String, values: ByteArray): Boolean {
+    val hrpExpanded: ByteArray = expandHrp(hrp)
+    val combined = ByteArray(hrpExpanded.size + values.size)
+    System.arraycopy(hrpExpanded, 0, combined, 0, hrpExpanded.size)
+    System.arraycopy(values, 0, combined, hrpExpanded.size, values.size)
+    return polymod(combined) == 1
+  }
+
+  class AddressFormatException(message: String): Exception(message) {
+
+  }
+
+  fun decodeUnlimitedLength(invoice: String): Boolean {
+    var lower = false
+    var upper = false
+    for (i in 0 until invoice.length) {
+      val c = invoice[i]
+      if (c.code < 33 || c.code > 126) throw AddressFormatException("Invalid character: $c, pos: $i")
+      if (c in 'a'..'z') {
+        if (upper) throw AddressFormatException("Invalid character: $c, pos: $i")
+        lower = true
+      }
+      if (c in 'A'..'Z') {
+        if (lower) throw AddressFormatException("Invalid character: $c, pos: $i")
+        upper = true
+      }
+    }
+    val pos = invoice.lastIndexOf('1')
+    if (pos < 1) throw AddressFormatException("Missing human-readable part")
+    val dataPartLength = invoice.length - 1 - pos
+    if (dataPartLength < 6) throw AddressFormatException("Data part too short: $dataPartLength")
+    val values = ByteArray(dataPartLength)
+    for (i in 0 until dataPartLength) {
+      val c = invoice[i + pos + 1]
+      if (CHARSET_REV.get(c.code).toInt() == -1) throw AddressFormatException("Invalid character: " + c + ", pos: " + (i + pos + 1))
+      values[i] = CHARSET_REV.get(c.code)
+    }
+    val hrp = invoice.substring(0, pos).lowercase(Locale.ROOT)
+    if (!verifyChecksum(hrp, values)) throw AddressFormatException("Invalid Checksum")
+    return true
+  }
+
+  /**
+   * Parses invoice amount according to
+   * https://github.com/lightningnetwork/lightning-rfc/blob/master/11-payment-encoding.md#human-readable-part
+   * @return invoice amount in bitcoins, zero if the invoice has no amount
+   * @throws RuntimeException if invoice format is incorrect
+   */
+  fun getAmount(invoice: String): BigDecimal {
+    try {
+      decodeUnlimitedLength(invoice) // checksum must match
+    } catch (e: AddressFormatException) {
+      throw IllegalArgumentException("Cannot decode invoice", e)
+    }
+
+    val matcher = invoicePattern.matcher(invoice)
+    require(matcher.matches()) { "Failed to match HRP pattern" }
+    val amountGroup = matcher.group("amount")
+    val multiplierGroup = matcher.group("multiplier")
+    if (amountGroup == null) {
+      return BigDecimal.ZERO
+    }
+    val amount = BigDecimal(amountGroup)
+    if (multiplierGroup == null) {
+      return amount
+    }
+    require(!(multiplierGroup == "p" && amountGroup[amountGroup.length - 1] != '0')) { "sub-millisatoshi amount" }
+    return amount.multiply(multiplier(multiplierGroup))
+  }
+
+  fun getAmountInSats(invoice: String): BigDecimal {
+    return getAmount(invoice).multiply(BigDecimal(100000000))
+  }
+
+  private fun multiplier(multiplier: String): BigDecimal {
+    return when (multiplier) {
+      "m" -> BigDecimal("0.001")
+      "u" -> BigDecimal("0.000001")
+      "n" -> BigDecimal("0.000000001")
+      "p" -> BigDecimal("0.000000000001")
+      else -> throw IllegalArgumentException("Invalid multiplier: $multiplier")
+    }
+  }
+
+  /**
+   * Finds LN invoice in the provided input string and returns it.
+   * For example for input = "aaa bbb lnbc1xxx ccc" it will return "lnbc1xxx"
+   * It will only return the first invoice found in the input.
+   *
+   * @return the invoice if it was found. null for null input or if no invoice is found
+   */
+  fun findInvoice(input: String?): String? {
+    if (input == null) {
+      return null
+    }
+    val matcher = invoicePattern.matcher(input)
+    return if (matcher.find()) {
+      matcher.group()
+    } else null
+  }
+}

app/src/main/java/com/vitorpamplona/amethyst/ui/components/RichTextViewer.kt

@@ -1,5 +1,6 @@
 package com.vitorpamplona.amethyst.ui.components
 
+import android.util.Patterns
 import androidx.compose.foundation.border
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.fillMaxWidth
@@ -27,6 +28,10 @@ val videoExtension = Pattern.compile("(.*/)*.+\\.(mp4|avi|wmv|mpg|amv|webm)$")
 val noProtocolUrlValidator = Pattern.compile("^[-a-zA-Z0-9@:%._\\+~#=]{1,256}\\.[a-zA-Z0-9()]{1,6}\\b(?:[-a-zA-Z0-9()@:%_\\+.~#?&//=]*)$")
 val tagIndex = Pattern.compile("\\#\\[([0-9]*)\\]")
 
+val mentionsPattern: Pattern = Pattern.compile("@([A-Za-z0-9_-]+)")
+val hashTagsPattern: Pattern = Pattern.compile("#([A-Za-z0-9_-]+)")
+val urlPattern: Pattern = Patterns.WEB_URL
+
 fun isValidURL(url: String?): Boolean {
   return try {
     URL(url).toURI()
@@ -47,7 +52,10 @@ fun RichTextViewer(content: String, tags: List<List<String>>?) {
       FlowRow() {
         paragraph.split(' ').forEach { word: String ->
           // Explicit URL
-          if (isValidURL(word)) {
+          val lnInvoice = LnInvoiceUtil.findInvoice(word)
+          if (lnInvoice != null) {
+            InvoicePreview(lnInvoice)
+          } else if (isValidURL(word)) {
             val removedParamsFromUrl = word.split("?")[0].toLowerCase()
             if (imageExtension.matcher(removedParamsFromUrl).matches()) {
               AsyncImage(

app/src/main/res/drawable/lightning.xml

@@ -0,0 +1,12 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="280dp"
+    android:height="280dp"
+    android:viewportWidth="280"
+    android:viewportHeight="280">
+  <path
+      android:pathData="M7,140.5C7,66.77 66.77,7 140.5,7C214.23,7 274,66.77 274,140.5C274,214.23 214.23,274 140.5,274C66.77,274 7,214.23 7,140.5Z"
+      android:fillColor="#f7931a"/>
+  <path
+      android:pathData="M161.19,51.5C153.23,72.16 145.28,94.41 135.72,116.66C135.72,116.66 135.72,119.84 138.91,119.84L204.17,119.84C204.17,119.84 204.17,121.43 205.77,123.02L110.25,229.5C108.66,227.91 108.66,226.32 108.66,224.73L142.09,153.21L142.09,146.86L75.23,146.86L75.23,140.5L156.42,51.5L161.19,51.5Z"
+      android:fillColor="#ffffff"/>
+</vector>