1 files changed, 58 insertions, 0 deletions
diff --git a/src/main/kotlin/RFC822Parser.kt b/src/main/kotlin/RFC822Parser.kt
new file mode 100644
index 0000000..4a6ce74
--- /dev/null
+++ b/src/main/kotlin/RFC822Parser.kt
@@ -0,0 +1,58 @@
+import kotlinx.coroutines.MainScope
+import java.io.ByteArrayOutputStream
+import java.io.File
+
+suspend fun main() {
+    val io = Protocol.IO.FromStreams(File("samplemail.txt").inputStream(), ByteArrayOutputStream())
+    val rfc = RFC822Parser()
+    rfc.executeAsync(MainScope(), io).join()
+    println(rfc.headers)
+    println("Content: ${rfc.content.decodeToString()}")
+}
+
+class RFC822Parser() : Protocol() {
+
+    class Header(val field: String, val value: ByteArray)
+
+    private val _headers = mutableListOf<Header>()
+    val headers: List<Header> get() = _headers
+    lateinit var content: ByteArray
+        private set
+
+    override suspend fun IO.execute() {
+        while (parseField()) Unit
+        content = readAll()
+    }
+
+    private suspend fun IO.parseField(): Boolean {
+        val read = readUntil(CRLF)
+        if (read.contentEquals(CRLF)) {
+            return false
+        }
+        val indexOfColon = read.indexOf(':'.code.toByte())
+        if (indexOfColon == -1) {
+            throw IllegalStateException("Expected : in MIME header")
+        }
+        val headerField = read.sliceArray(0 until indexOfColon).decodeToString().trim()
+        var data = read.sliceArray(indexOfColon + 1 until read.size)
+        while (true) {
+            val nextLine = readUntil(CRLF)
+            if (nextLine.isNotEmpty() && isWhitespaceCharacter(nextLine[0])) {
+                val oldSize = data.size
+                data = data.copyOf(oldSize + nextLine.size)
+                nextLine.copyInto(data, oldSize)
+            } else {
+                pushBack(CRLF)
+                pushBack(nextLine)
+                break
+            }
+        }
+        _headers.add(Header(headerField, data))
+        return true
+    }
+
+    fun isWhitespaceCharacter(char: Byte): Boolean {
+        val char = char.toInt().toChar()
+        return char == ' ' || char == '\t'
+    }
+}