creating the structure of contact exporting

app/src/main/kotlin/com/simplemobiletools/contacts/activities/MainActivity.kt

@@ -22,7 +22,10 @@ import com.simplemobiletools.contacts.dialogs.FilterContactSourcesDialog
 import com.simplemobiletools.contacts.dialogs.ImportContactsDialog
 import com.simplemobiletools.contacts.extensions.config
 import com.simplemobiletools.contacts.extensions.onTabSelectionChanged
+import com.simplemobiletools.contacts.helpers.ContactsHelper
+import com.simplemobiletools.contacts.helpers.VcfExporter
 import com.simplemobiletools.contacts.interfaces.RefreshContactsListener
+import com.simplemobiletools.contacts.models.Contact
 import kotlinx.android.synthetic.main.activity_main.*
 import kotlinx.android.synthetic.main.fragment_contacts.*
 import kotlinx.android.synthetic.main.fragment_favorites.*
@@ -281,7 +284,23 @@ class MainActivity : SimpleActivity(), RefreshContactsListener {
     private fun exportContacts() {
         FilePickerDialog(this, pickFile = false, showFAB = true) {
             ExportContactsDialog(this, it) { file, contactSources ->
-
+                Thread {
+                    ContactsHelper(this).getContacts {
+                        val contacts = it.filter { contactSources.contains(it.source) }
+                        if (contacts.isEmpty()) {
+                            toast(R.string.no_entries_for_exporting)
+                        } else {
+                            toast(R.string.exporting)
+                            VcfExporter().exportContacts(this, file, contacts as ArrayList<Contact>) {
+                                toast(when (it) {
+                                    VcfExporter.ExportResult.EXPORT_OK -> R.string.exporting_successful
+                                    VcfExporter.ExportResult.EXPORT_PARTIAL -> R.string.exporting_some_entries_failed
+                                    else -> R.string.exporting_failed
+                                })
+                            }
+                        }
+                    }
+                }.start()
             }
         }
     }

app/src/main/kotlin/com/simplemobiletools/contacts/helpers/VcfExporter.kt

@@ -0,0 +1,37 @@
+package com.simplemobiletools.contacts.helpers
+
+import com.simplemobiletools.commons.activities.BaseSimpleActivity
+import com.simplemobiletools.commons.extensions.getFileOutputStream
+import com.simplemobiletools.contacts.helpers.VcfExporter.ExportResult.*
+import com.simplemobiletools.contacts.models.Contact
+import java.io.File
+
+class VcfExporter() {
+    enum class ExportResult {
+        EXPORT_FAIL, EXPORT_OK, EXPORT_PARTIAL
+    }
+
+    private var contactsExported = 0
+    private var contactsFailed = 0
+
+    fun exportContacts(activity: BaseSimpleActivity, file: File, contacts: ArrayList<Contact>, callback: (result: ExportResult) -> Unit) {
+        activity.getFileOutputStream(file) {
+            if (it == null) {
+                callback(EXPORT_FAIL)
+                return@getFileOutputStream
+            }
+
+            it.bufferedWriter().use { out ->
+                for (contact in contacts) {
+
+                }
+            }
+        }
+
+        callback(when {
+            contactsExported == 0 -> EXPORT_FAIL
+            contactsFailed > 0 -> EXPORT_PARTIAL
+            else -> EXPORT_OK
+        })
+    }
+}