Extract custom sync server help URL into a separate string

Author: oakkitten

AnkiDroid/src/main/java/com/ichi2/anki/preferences/HtmlHelpPreference.kt

@@ -14,38 +14,54 @@
 
 package com.ichi2.anki.preferences
 
-import android.R
 import android.content.Context
 import android.text.method.LinkMovementMethod
 import android.util.AttributeSet
 import android.widget.TextView
-import androidx.core.text.HtmlCompat
+import androidx.core.text.parseAsHtml
 import androidx.preference.Preference
 import androidx.preference.PreferenceViewHolder
+import com.ichi2.anki.R
 
 /**
- * Non-clickable preference that shows help text. In XML, you only want to specify the summary, e.g.
+ * Non-clickable preference that shows help text.
  *
- *     <com.ichi2.anki.preferences.HtmlHelpPreference android:summary="@string/foo" />
+ * The summary is parsed as a format string containing HTML,
+ * and may contain up to three format specifiers as understood by `Sting.format()`,
+ * arguments for which can be specified using XML attributes such as `app:substitution1`.
  *
- * The summary is parsed as HTML, which can contain all tags that TextViews can display,
+ *     <com.ichi2.anki.preferences.HtmlHelpPreference
+ *         android:summary="@string/format_string"
+ *         app:substitution1="@string/substitution1"
+ *         />
+ *
+ * The summary HTML can contain all tags that TextViews can display,
  * including new lines and links. Raw HTML can be entered using the CDATA tag, e.g.
  *
- *     <string name="foo"><![CDATA[<b>Bold text</b>]]></string>
+ *     <string name="format_string"><![CDATA[<b>Hello, %s</b>]]></string>
  */
 class HtmlHelpPreference(context: Context, attrs: AttributeSet?) : Preference(context, attrs) {
     init {
         isSelectable = false
         isPersistent = false
     }
 
-    override fun getSummary() = super.getSummary()?.let {
-        HtmlCompat.fromHtml(it.toString(), HtmlCompat.FROM_HTML_MODE_LEGACY)
+    private val substitutions = context.usingStyledAttributes(attrs, R.styleable.HtmlHelpPreference) {
+        arrayOf(
+            getString(R.styleable.HtmlHelpPreference_substitution1),
+            getString(R.styleable.HtmlHelpPreference_substitution2),
+            getString(R.styleable.HtmlHelpPreference_substitution3),
+        )
     }
 
+    override fun getSummary() = super.getSummary()
+        .toString()
+        .format(*substitutions)
+        .parseAsHtml()
+
     override fun onBindViewHolder(holder: PreferenceViewHolder) {
         super.onBindViewHolder(holder)
-        val summary = holder.findViewById(R.id.summary) as TextView
+        val summary = holder.findViewById(android.R.id.summary) as TextView
         summary.movementMethod = LinkMovementMethod.getInstance()
         summary.maxHeight = Int.MAX_VALUE
     }

AnkiDroid/src/main/java/com/ichi2/anki/preferences/PreferenceUtils.kt

@@ -15,11 +15,19 @@
  */
 package com.ichi2.anki.preferences
 
+import android.content.Context
+import android.content.res.TypedArray
+import android.util.AttributeSet
+import androidx.annotation.AttrRes
 import androidx.annotation.StringRes
+import androidx.annotation.StyleRes
 import androidx.fragment.app.DialogFragment
 import androidx.fragment.app.Fragment
 import androidx.preference.Preference
 import androidx.preference.PreferenceFragmentCompat
+import kotlin.contracts.ExperimentalContracts
+import kotlin.contracts.InvocationKind
+import kotlin.contracts.contract
 
 /**
  * By implementing this interface, a preference can specify which dialog fragment is opened on click.
@@ -68,3 +76,24 @@ inline fun <reified T : Preference> PreferenceFragmentCompat.requirePreference(@
     val key = getString(resId)
     return requirePreference(key)
 }
+
+/**
+ * Run a [block] on a [TypedArray] receiver that is recycled at the end.
+ * @return The return value of the block.
+ *
+ * @see android.content.res.Resources.Theme.obtainStyledAttributes
+ * @see androidx.core.content.withStyledAttributes
+ */
+@OptIn(ExperimentalContracts::class)
+inline fun <T> Context.usingStyledAttributes(
+    set: AttributeSet?,
+    attrs: IntArray,
+    @AttrRes defStyleAttr: Int = 0,
+    @StyleRes defStyleRes: Int = 0,
+    block: TypedArray.() -> T
+): T {
+    contract { callsInPlace(block, InvocationKind.EXACTLY_ONCE) }
+
+    val typedArray = obtainStyledAttributes(set, attrs, defStyleAttr, defStyleRes)
+    return typedArray.block().also { typedArray.recycle() }
+}

AnkiDroid/src/main/res/values/10-preferences.xml

@@ -224,7 +224,7 @@
         For example, you could use the sync server built into Anki
         Desktop to sync the collection when you only have a local network,
         and AnkiWeb to sync media when you have general internet access.
-        <a href="https://docs.ankidroid.org/#_custom_sync_server">Learn more</a>
+        <a href="%s">Learn more</a>
         <br>
         <br>Note: unlike in previous AnkiDroid versions,
         you must specify the full custom sync URL,

AnkiDroid/src/main/res/values/attrs.xml

@@ -42,6 +42,12 @@
         <attr name="summaryFormat" format="string"/>
     </declare-styleable>
 
+    <declare-styleable name="HtmlHelpPreference">
+        <attr name="substitution1" format="string" />
+        <attr name="substitution2" format="string" />
+        <attr name="substitution3" format="string" />
+    </declare-styleable>
+
     <declare-styleable name="HeaderPreference">
         <!-- String array of entries to join in order to build the preference summary -->
         <attr name="summaryEntries" format="reference"/>

AnkiDroid/src/main/res/values/constants.xml

@@ -165,6 +165,7 @@
     <string name="link_distributions">https://apps.ankiweb.net/#download</string>
     <string name="link_ankiweb_lost_email_instructions">https://github.com/ankidroid/Anki-Android/wiki/FAQ#forgotten-ankiweb-email-instructions</string>
     <string name="link_scoped_storage_faq">https://github.com/ankidroid/Anki-Android/wiki/Storage-Migration-FAQ</string>
+    <string name="link_custom_sync_server_help_learn_more_en">https://docs.ankidroid.org/#_custom_sync_server</string>
 
     <string-array name="leech_action_values">
         <item>0</item>

AnkiDroid/src/main/res/xml/preferences_custom_sync_server.xml

@@ -9,6 +9,7 @@
     android:key="@string/pref_custom_sync_server_screen_key">
     <com.ichi2.anki.preferences.HtmlHelpPreference
         android:summary="@string/custom_sync_server_help"
+        app:substitution1="@string/link_custom_sync_server_help_learn_more_en"
         search:ignore="true" />
     <com.ichi2.anki.preferences.VersatileTextWithASwitchPreference
         android:key="@string/custom_sync_server_collection_url_key"