feat(lsp/java): add basic snippet support for Java

lsp/java/src/main/java/com/itsaky/androidide/lsp/java/edits/AdvancedJavaEditHandler.kt

@@ -41,9 +41,7 @@ abstract class AdvancedJavaEditHandler(protected val file: Path) : BaseJavaEditH
     index: Int
   ) {
     val compiler = JavaCompilerProvider.get(ProjectManager.findModuleForFile(file) ?: return)
-    if (compiler != null) {
-      performEdits(compiler, editor, item)
-    }
+    performEdits(compiler, editor, item)
 
     executeCommand(editor, item.command)
   }

lsp/java/src/main/java/com/itsaky/androidide/lsp/java/providers/completion/IJavaCompletionProvider.kt

@@ -24,6 +24,7 @@ import com.itsaky.androidide.lsp.java.compiler.JavaCompilerService
 import com.itsaky.androidide.lsp.java.edits.ClassImportEditHandler
 import com.itsaky.androidide.lsp.java.models.JavaCompletionItem
 import com.itsaky.androidide.lsp.java.providers.BaseJavaServiceProvider
+import com.itsaky.androidide.lsp.java.providers.snippet.JavaSnippet
 import com.itsaky.androidide.lsp.java.utils.EditHelper
 import com.itsaky.androidide.lsp.models.ClassCompletionData
 import com.itsaky.androidide.lsp.models.Command
@@ -42,6 +43,7 @@ import com.itsaky.androidide.lsp.models.ICompletionData
 import com.itsaky.androidide.lsp.models.InsertTextFormat.SNIPPET
 import com.itsaky.androidide.lsp.models.MatchLevel
 import com.itsaky.androidide.lsp.models.MethodCompletionData
+import com.itsaky.androidide.preferences.utils.indentationString
 import com.itsaky.androidide.progress.ProgressManager.Companion.abortIfCancelled
 import com.itsaky.androidide.utils.ILogger
 import java.nio.file.Path
@@ -291,6 +293,23 @@ abstract class IJavaCompletionProvider(
     }
   }
 
+  protected open fun snippetItem(snippet: JavaSnippet, matchLevel: MatchLevel, partial: String, indent: Int) : CompletionItem {
+    return JavaCompletionItem().apply {
+      this.label = snippet.label
+      this.detail = snippet.description
+      this.completionKind = CompletionItemKind.SNIPPET
+      this.matchLevel = matchLevel
+      this.ideSortText = snippet.prefix
+      this.snippetDescription = describeSnippet(snippet.prefix)
+
+      val indentation = indentationString(indent)
+      this.insertTextFormat = SNIPPET
+      this.insertText = snippet.content.joinToString(separator = "\n") {
+        indentation + it.replace("\t", indentationString)
+      }
+    }
+  }
+
   protected open fun kind(e: Element): CompletionItemKind {
     abortIfCancelled()
     abortCompletionIfCancelled()

lsp/java/src/main/java/com/itsaky/androidide/lsp/java/providers/completion/IdentifierCompletionProvider.kt

@@ -23,8 +23,8 @@ import com.itsaky.androidide.lsp.java.compiler.JavaCompilerService
 import com.itsaky.androidide.lsp.models.CompletionItem
 import com.itsaky.androidide.lsp.models.CompletionResult
 import com.itsaky.androidide.progress.ProgressManager.Companion.abortIfCancelled
-import openjdk.source.util.TreePath
 import java.nio.file.Path
+import openjdk.source.util.TreePath
 
 /** @author Akash Yadav */
 class IdentifierCompletionProvider(
@@ -44,6 +44,12 @@ class IdentifierCompletionProvider(
 
     abortIfCancelled()
     abortCompletionIfCancelled()
+
+    val snippets =
+      SnippetCompletionProvider(cursor, file, compiler, settings)
+        .complete(task, path, partial, endsWithParen)
+    list.addAll(snippets.items)
+
     val scopeMembers =
       ScopeCompletionProvider(file, cursor, compiler, settings)
         .complete(task, path, partial, endsWithParen)
@@ -52,13 +58,7 @@ class IdentifierCompletionProvider(
     abortIfCancelled()
     abortCompletionIfCancelled()
     val staticImports =
-      StaticImportCompletionProvider(
-          file,
-          cursor,
-          compiler,
-          settings,
-          path.compilationUnit
-        )
+      StaticImportCompletionProvider(file, cursor, compiler, settings, path.compilationUnit)
         .complete(task, path, partial, endsWithParen)
     list.addAll(staticImports.items)
 
@@ -68,13 +68,7 @@ class IdentifierCompletionProvider(
         abortIfCancelled()
         abortCompletionIfCancelled()
         val classNames =
-          ClassNamesCompletionProvider(
-              file,
-              cursor,
-              compiler,
-              settings,
-              path.compilationUnit
-            )
+          ClassNamesCompletionProvider(file, cursor, compiler, settings, path.compilationUnit)
             .complete(task, path, partial, endsWithParen)
         list.addAll(classNames.items)
       }

lsp/java/src/main/java/com/itsaky/androidide/lsp/java/providers/completion/SnippetCompletionProvider.kt

@@ -0,0 +1,114 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.lsp.java.providers.completion
+
+import com.itsaky.androidide.lsp.api.IServerSettings
+import com.itsaky.androidide.lsp.java.compiler.CompileTask
+import com.itsaky.androidide.lsp.java.compiler.JavaCompilerService
+import com.itsaky.androidide.lsp.java.providers.snippet.JavaSnippet
+import com.itsaky.androidide.lsp.java.providers.snippet.JavaSnippetRepository
+import com.itsaky.androidide.lsp.java.providers.snippet.JavaSnippetScope
+import com.itsaky.androidide.lsp.java.utils.EditHelper
+import com.itsaky.androidide.lsp.models.CompletionItem
+import com.itsaky.androidide.lsp.models.CompletionResult
+import com.itsaky.androidide.lsp.models.MatchLevel
+import java.nio.file.Path
+import openjdk.source.tree.ClassTree
+import openjdk.source.tree.CompilationUnitTree
+import openjdk.source.tree.MethodTree
+import openjdk.source.util.TreePath
+
+/**
+ * Provides snippet completion for Java files.
+ *
+ * @author Akash Yadav
+ */
+class SnippetCompletionProvider(
+  cursor: Long,
+  completingFile: Path,
+  compiler: JavaCompilerService,
+  settings: IServerSettings
+) : IJavaCompletionProvider(cursor, completingFile, compiler, settings) {
+
+  override fun doComplete(
+    task: CompileTask,
+    path: TreePath,
+    partial: String,
+    endsWithParen: Boolean
+  ): CompletionResult {
+    val scope = findSnippetScope(path) ?: return CompletionResult.EMPTY
+    return when (scope.leaf) {
+      is CompilationUnitTree -> completeTopLevelSnippets(task, path, partial)
+      is ClassTree -> completeMemberSnippets(task, path, partial)
+      is MethodTree -> completeLocalSnippets(task, path, partial)
+      else -> CompletionResult.EMPTY
+    }
+  }
+
+  private fun completeTopLevelSnippets(
+    task: CompileTask,
+    path: TreePath,
+    partial: String
+  ): CompletionResult {
+    return CompletionResult.EMPTY
+  }
+
+  private fun completeMemberSnippets(
+    task: CompileTask,
+    path: TreePath,
+    partial: String
+  ): CompletionResult {
+    return CompletionResult.EMPTY
+  }
+
+  private fun completeLocalSnippets(
+    task: CompileTask,
+    path: TreePath,
+    partial: String
+  ): CompletionResult {
+    val items = mutableListOf<CompletionItem>()
+    val snippets =
+      mutableListOf<JavaSnippet>().apply {
+        JavaSnippetRepository.snippets[JavaSnippetScope.LOCAL]?.let { addAll(it) }
+        JavaSnippetRepository.snippets[JavaSnippetScope.GLOBAL]?.let { addAll(it) }
+      }
+
+    val indent = EditHelper.indent(task.task, task.root(), path.leaf)
+    for (snippet in snippets) {
+      val matchLevel = matchLevel(snippet.prefix, partial)
+      if (matchLevel == MatchLevel.NO_MATCH) {
+        continue
+      }
+
+      items.add(snippetItem(snippet, matchLevel, partial, indent))
+    }
+
+    return CompletionResult(items)
+  }
+
+  private fun findSnippetScope(path: TreePath?): TreePath? {
+    var treePath = path
+    while (treePath != null) {
+      if (treePath.leaf.let { it is CompilationUnitTree || it is ClassTree || it is MethodTree }) {
+        return treePath
+      }
+      treePath = treePath.parentPath
+    }
+    return null
+  }
+}

lsp/java/src/main/java/com/itsaky/androidide/lsp/java/providers/snippet/JavaSnippet.kt

@@ -0,0 +1,58 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.lsp.java.providers.snippet
+
+/**
+ * Java snippet.
+ *
+ * @author Akash Yadav
+ */
+data class JavaSnippet(
+  val prefix: String,
+  val label: String,
+  val description: String,
+  val content: Array<String>
+) {
+
+  constructor(
+    prefix: String,
+    label: String,
+    description: String,
+    content: () -> Array<String>
+  ) : this(prefix, label, description, content())
+
+  override fun equals(other: Any?): Boolean {
+    if (this === other) return true
+    if (other !is JavaSnippet) return false
+
+    if (label != other.label) return false
+    if (description != other.description) return false
+    if (prefix != other.prefix) return false
+    if (!content.contentEquals(other.content)) return false
+
+    return true
+  }
+
+  override fun hashCode(): Int {
+    var result = label.hashCode()
+    result = 31 * result + description.hashCode()
+    result = 31 * result + prefix.hashCode()
+    result = 31 * result + content.contentHashCode()
+    return result
+  }
+}

lsp/java/src/main/java/com/itsaky/androidide/lsp/java/providers/snippet/JavaSnippetRepository.kt

@@ -0,0 +1,60 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.lsp.java.providers.snippet
+
+/**
+ * Repository to store various snippets for Java.
+ *
+ * @author Akash Yadav
+ */
+object JavaSnippetRepository {
+
+  val snippets: Map<JavaSnippetScope, List<JavaSnippet>> by lazy { createSnippets() }
+
+  private fun createSnippets(): Map<JavaSnippetScope, List<JavaSnippet>> {
+    return mutableMapOf<JavaSnippetScope, List<JavaSnippet>>().apply {
+      this[JavaSnippetScope.GLOBAL] = createGlobalSnippets()
+      this[JavaSnippetScope.TOP_LEVEL] = createTopLevelSnippets()
+      this[JavaSnippetScope.MEMBER] = createMemberSnippets()
+      this[JavaSnippetScope.LOCAL] = createLocalSnippets()
+    }
+  }
+
+  private fun createGlobalSnippets(): List<JavaSnippet> {
+    return listOf()
+  }
+
+  private fun createTopLevelSnippets(): List<JavaSnippet> {
+    return listOf()
+  }
+
+  private fun createMemberSnippets(): List<JavaSnippet> {
+    return listOf()
+  }
+
+  private fun createLocalSnippets(): List<JavaSnippet> {
+    return listOf(
+      JavaSnippet("for", "Indexed for loop", "0 -> count") {
+        arrayOf("for (int \${1:i} = 0; \$1 < \${2:count}; ++\$1) {", "\t\$0", "}")
+      },
+      JavaSnippet("forr", "Reverse-indexed for loop", "count-1 -> 0") {
+        arrayOf("for (int \${1:i} = \${2:count} - 1; \$1 >= 0; --\$1) {", "\t\$0", "}")
+      }
+    )
+  }
+}

lsp/java/src/main/java/com/itsaky/androidide/lsp/java/providers/snippet/JavaSnippetScope.kt

@@ -0,0 +1,41 @@
+/*
+ *  This file is part of AndroidIDE.
+ *
+ *  AndroidIDE is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  AndroidIDE is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.itsaky.androidide.lsp.java.providers.snippet
+
+/**
+ * Scope for [JavaSnippet].
+ *
+ * @author Akash Yadav
+ */
+enum class JavaSnippetScope {
+
+  /**
+   * Snippets that can be used at the top level. This includes snippes such as class, interface,
+   * enum templates.
+   */
+  TOP_LEVEL,
+
+  /** Snippets that can be used at the member level i.e. inside a class tree. */
+  MEMBER,
+
+  /** Snippets that can be used at a local level. E.g. inside a method or constructor. */
+  LOCAL,
+
+  /** Snippets that can be used anywhere in the code, irrespective of the current scope. */
+  GLOBAL
+}