MimeType: add class with tests, woah!

app/src/main/java/dev/lowrespalmtree/comet/MimeType.kt

@@ -0,0 +1,37 @@
+package dev.lowrespalmtree.comet
+
+class MimeType(
+    val main: String,
+    val sub: String,
+    val params: Map<String, String>
+) {
+    val short: String get() = "${main.ifEmpty { "*" }}/${sub.ifEmpty { "*" }}"
+    val charset: String get() = params.getOrDefault("charset", DEFAULT_CHARSET)
+
+    companion object {
+        const val DEFAULT_CHARSET = "utf-8"
+        val DEFAULT = MimeType("text", "gemini", mapOf("charset" to DEFAULT_CHARSET))
+
+        fun from(string: String): MimeType? {
+            val typeString: String
+            val params: Map<String, String>
+            if (";" in string) {
+                val elements = string.split(";")
+                typeString = elements[0]
+                params = mutableMapOf<String, String>()
+                elements.subList(1, elements.size)
+                    .map { it.trim().lowercase() }
+                    .map { p -> if (p.count { it == '=' } != 1) return@from null else p }
+                    .map { it.split('=') }
+                    .forEach { params[it[0]] = it[1] }
+            } else {
+                typeString = string.trim()
+                params = mapOf()
+            }
+            if (typeString.count { it == '/' } != 1)
+                return null
+            val (main, sub) = typeString.split('/').map { it.trim() }
+            return MimeType(main, sub, params)
+        }
+    }
+}

app/src/test/java/dev/lowrespalmtree/comet/MimeTypeTests.kt

@@ -0,0 +1,38 @@
+package dev.lowrespalmtree.comet
+
+import org.junit.Assert.*
+import org.junit.Test
+
+class MimeTypeTests {
+    @Test
+    fun from() {
+        assertNull(MimeType.from(""))
+        assertNull(MimeType.from("dumb"))
+        assertNull(MimeType.from("dumb;dumber"))
+        assertNull(MimeType.from("123456"))
+
+        MimeType.from("a/b")?.run {
+            assertEquals("a", main)
+            assertEquals("b", sub)
+            assertEquals(mapOf<String, String>(), params)
+        } ?: fail()
+
+        MimeType.from("text/gemini")?.run {
+            assertEquals("text", main)
+            assertEquals("gemini", sub)
+            assertEquals(mapOf<String, String>(), params)
+        } ?: fail()
+
+        MimeType.from("text/gemini;lang=en")?.run {
+            assertEquals("text", main)
+            assertEquals("gemini", sub)
+            assertEquals(mapOf("lang" to "en"), params)
+        } ?: fail()
+
+        MimeType.from("text/gemini ;lang=en")?.run {
+            assertEquals("text", main)
+            assertEquals("gemini", sub)
+            assertEquals(mapOf("lang" to "en"), params)
+        } ?: fail()
+    }
+}