MimeType: use it to process responses accordingly

This prevents Comet from showing JPGs as Gemtext, whew… Any unhandled
MIME type now presents an alert, and we should slowly support more and
more types.

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

@@ -18,7 +18,7 @@ class MimeType(
             if (";" in string) {
                 val elements = string.split(";")
                 typeString = elements[0]
-                params = mutableMapOf<String, String>()
+                params = mutableMapOf()
                 elements.subList(1, elements.size)
                     .map { it.trim().lowercase() }
                     .map { p -> if (p.count { it == '=' } != 1) return@from null else p }

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

@@ -8,7 +8,6 @@ import androidx.lifecycle.SavedStateHandle
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import androidx.preference.PreferenceManager
-import dev.lowrespalmtree.comet.utils.joinUrls
 import dev.lowrespalmtree.comet.utils.resolveLinkUri
 import kotlinx.coroutines.*
 import kotlinx.coroutines.channels.onSuccess
@@ -147,6 +146,20 @@ class PageViewModel(@Suppress("unused") private val savedStateHandle: SavedState
 
     @ExperimentalCoroutinesApi
     private suspend fun handleSuccessResponse(response: Response, uri: Uri) {
+        val mimeType = MimeType.from(response.meta) ?: MimeType.DEFAULT  // Spec. section 3.3 last §
+        when (mimeType.main) {
+            "text" -> {
+                if (mimeType.sub == "gemini")
+                    handleSuccessGemtextResponse(response, uri)
+                else
+                    handleSuccessGenericTextResponse(response, uri)
+            }
+            else -> signalError("No idea how to process a \"${mimeType.short}\" file.")
+        }
+    }
+
+    @ExperimentalCoroutinesApi
+    private suspend fun handleSuccessGemtextResponse(response: Response, uri: Uri) {
         state.postValue(State.RECEIVING)
         val uriString = uri.toString()
 
@@ -199,6 +212,10 @@ class PageViewModel(@Suppress("unused") private val savedStateHandle: SavedState
         state.postValue(State.IDLE)
     }
 
+    @ExperimentalCoroutinesApi
+    private suspend fun handleSuccessGenericTextResponse(response: Response, uri: Uri) =
+        handleSuccessGemtextResponse(response, uri)  // TODO render plain text as... something else?
+
     private fun handleRedirectResponse(response: Response, redirects: Int) {
         event.postValue(RedirectEvent(response.meta, redirects))
     }