Ask the user to install a PDF reader

app/src/main/java/net/underdesk/circolapp/adapters/AttachmentAdapter.kt

@@ -28,6 +28,7 @@ import android.view.View
 import android.view.ViewGroup
 import android.widget.ImageButton
 import android.widget.TextView
+import androidx.appcompat.app.AlertDialog
 import androidx.recyclerview.widget.RecyclerView
 import kotlinx.android.synthetic.main.item_attachment.view.*
 import net.underdesk.circolapp.R
@@ -59,7 +60,22 @@ class AttachmentAdapter(
         holder.viewButton.setOnClickListener {
             val viewIntent = Intent(Intent.ACTION_VIEW)
             viewIntent.setDataAndType(Uri.parse(attachmentsUrls[position]), "application/pdf")
-            context.startActivity(viewIntent)
+            if (viewIntent.resolveActivity(context.packageManager) != null) {
+                context.startActivity(viewIntent)
+            } else {
+                val builder = AlertDialog.Builder(context)
+                builder.apply {
+                    setTitle(R.string.dialog_install_pdf_reader_title)
+                    setMessage(R.string.dialog_install_pdf_reader_content)
+                    setPositiveButton(
+                        R.string.dialog_ok
+                    ) { dialog, _ ->
+                        dialog.dismiss()
+                    }
+                }
+
+                builder.create().show()
+            }
         }
 
         holder.downloadButton.setOnClickListener {

app/src/main/java/net/underdesk/circolapp/adapters/CircularLetterAdapter.kt

@@ -146,7 +146,22 @@ class CircularLetterAdapter(
         holder.viewButton.setOnClickListener {
             val viewIntent = Intent(Intent.ACTION_VIEW)
             viewIntent.setDataAndType(Uri.parse(circulars[position].url), "application/pdf")
-            context.startActivity(viewIntent)
+            if (viewIntent.resolveActivity(context.packageManager) != null) {
+                context.startActivity(viewIntent)
+            } else {
+                val builder = AlertDialog.Builder(context)
+                builder.apply {
+                    setTitle(R.string.dialog_install_pdf_reader_title)
+                    setMessage(R.string.dialog_install_pdf_reader_content)
+                    setPositiveButton(
+                        R.string.dialog_ok
+                    ) { dialog, _ ->
+                        dialog.dismiss()
+                    }
+                }
+
+                builder.create().show()
+            }
         }
 
         holder.downloadButton.setOnClickListener {

app/src/main/res/values-it/strings.xml

@@ -45,6 +45,9 @@
     Le circolari sono scritte e pubblicate dal Liceo Scientifico Maria Curie di Pinerolo, e sono scaricate direttamente da https://curiepinerolo.edu.it/.\n
     Questi documenti sono rilasciati secondo la licenza "Attribution-NonCommercial-ShareAlike 3.0 Unported" (CC BY-NC-SA 3.0)(https://creativecommons.org/licenses/by-nc-sa/3.0/), come specificato in questa pagina: https://curiepinerolo.edu.it/note-legali/</string>
 
+    <string name="dialog_install_pdf_reader_title">Lettore PDF non installato</string>
+    <string name="dialog_install_pdf_reader_content">Installa un lettore di PDF per aprire le circolari</string>
+
     <string name="dialog_title_permission_required">Autorizzazioni richieste</string>
     <string name="dialog_message_permission_write">È necessaria la tua autorizzazione per salvare questa circolare nella memoria interna</string>
 

app/src/main/res/values/strings.xml

@@ -46,6 +46,9 @@
     Circulars letters are written by the Liceo Scientifico Maria Curie Pinerolo, and are downloaded directly from https://curiepinerolo.edu.it/.\n
     Those documents are released under the "Attribution-NonCommercial-ShareAlike 3.0 Unported (CC BY-NC-SA 3.0)(https://creativecommons.org/licenses/by-nc-sa/3.0/), as specified in this page: https://curiepinerolo.edu.it/note-legali</string>
 
+    <string name="dialog_install_pdf_reader_title">PDF reader not found</string>
+    <string name="dialog_install_pdf_reader_content">Please install an external application to open circular letters</string>
+
     <string name="dialog_title_permission_required">Permission required</string>
     <string name="dialog_message_permission_write">We need your permission to save this circular letter to local storage</string>