Plugin: How to insert new method in existing PHP class? - intellij-idea

Question

I'm trying to create a IntelliJ plugin (mostly for learning purposes). My aim is that by pressing a keyboard shortcut the plugin will generate a corresponding PHP unit test method stub in the test file.
So let's say Db.php is open, the upon pressing Ctrl+Shift+U the plugin will create a unit test stub in DbTest.php.
So far I've figured out how to get the method name at cursor and how to locate the corresponding Unit test file (i.e. Db => DbTest) as PsiFile.
PsiFile[] search = FilenameIndex.getFilesByName(project, testFileName, scope); //scope is the test directory
PsiFile testFile = search[0];
What I cannot figure out is how to insert the generated new method stub this in testFile and then save the changes?
P.S. I see there exists a createMethodFromText function but how do I get the PsiClass from PsiFile? Also how do I save the changes?

Answer 1

There're just a few simple steps.
Find PhpClass you want to insert a new method in. As you already have PsiFile you can either traverse a tree manually or use PhpElementVisitor.
1.1. To travers a tree manually you can use PsiTreeUtil#findChildOfType method. In your case you'll need to find GroupStatement first, then the class you need.
1.2. Invoke PsiElement#accept method (PsiFile is an instance of PsiElement) provided with PhpElementVisitor with overridden #visitPhpGroupStatement and #visitPhpClass methods.
Use PhpPsiElementFactory#createMethod to create the new method from text. Note that this class isn't a part of the public API, so theoretically it can be easily changed/moved/removed/whatever in the future.
Use PsiElement#add (PhpClass is also an instance of PsiElement) to insert the method into the class.
That's all. You don't need to explicitly save the changes.

Answer 2

Here is what worked for me in the end. Thanks everyone for the help
for (int i = 0; i < found.getTextLength(); i++) {
PsiElement ele = found.findElementAt(i);
PhpClass phpClass = PsiTreeUtil.getParentOfType(ele, PhpClass.class);
if (phpClass != null) {
Method methodExists = findMethod(phpClass, methodName);
if (methodExists == null) {
new WriteCommandAction.Simple(phpClass.getProject(), phpClass.getContainingFile()) {
#Override
protected void run() throws Throwable {
PsiElement brace = phpClass.getLastChild();
if (brace != null) {
Method method = PhpPsiElementFactory.createMethod(phpClass.getProject(), "public function " + methodName + "() {\n\n}");
CodeStyleManager styleManager = CodeStyleManager.getInstance(getProject());
styleManager.reformat(method);
PsiElement newMethod = phpClass.addBefore(method, brace);
PsiNavigateUtil.navigate(newMethod);
}
}
}.execute();
} else {
PsiNavigateUtil.navigate(methodExists);
}
break;
}
}