feat(cdl): add CDL event handler parsing and snippet support

This adds a small DSL-aware helper to extract CDL event
declarations and generate a ready-to-use snippet. It also
extends hover support to show the snippet and parameter
hints for CDL events, improving developer productivity.

- Generate a MOM event handler scaffold and local vars
- Hover shows the generated snippet and mom_ parameter hints

client/src/common/handlers.ts

@@ -1,4 +1,8 @@
 import * as vscode from "vscode"
+import {
+    cdlEventHandlerAtLine,
+    createCdlEventHandlerSnippet
+} from "./cdlEventHandler"
 
 export function formatCdlFile(content: string): string {
     let indentLevel = 0
@@ -110,30 +114,33 @@ export function completionHandlerCdl(document: vscode.TextDocument, position: vs
 }
 
 export function hoverCdlHandler(document: vscode.TextDocument, position: vscode.Position) {
-    const wordRange = document.getWordRangeAtPosition(position)
-    const word = document.getText(wordRange)
-    const text = document.getText()
-    const lines = text.split("\n")
-
-    let hoverText: string | undefined
-
-    for (const line of lines) {
-        const words = line.split(/\s+/)
-        const wordIndex = words.indexOf(word)
-
-        if (wordIndex > 0) {
-            if (words[wordIndex - 1] === "EVENT") {
-                hoverText = `MOM_${word}`
-            } else if (words[wordIndex - 1] === "PARAM") {
-                hoverText = `mom_${word}`
+    const line = document.lineAt(position.line).text
+    const eventMatch = /^\s*EVENT\s+([^\s{]+)/.exec(line)
+    if (eventMatch) {
+        const eventStart = line.indexOf(eventMatch[1], eventMatch.index)
+        const declarationEnd = eventStart + eventMatch[1].length
+        if (position.character <= declarationEnd) {
+            const handler = cdlEventHandlerAtLine(document.getText(), position.line)
+            if (handler) {
+                const markdown = new vscode.MarkdownString()
+                markdown.appendCodeblock(createCdlEventHandlerSnippet(handler), "tcl")
+                return new vscode.Hover(
+                    markdown,
+                    new vscode.Range(position.line, eventMatch.index, position.line, declarationEnd)
+                )
             }
-            break
         }
     }
 
-    if (hoverText) {
-        return new vscode.Hover(hoverText)
+    const parameterMatch = /^\s*PARAM\s+([^\s{]+)/.exec(line)
+    if (parameterMatch) {
+        const parameterStart = line.indexOf(parameterMatch[1], parameterMatch.index)
+        const parameterEnd = parameterStart + parameterMatch[1].length
+        if (position.character >= parameterStart && position.character <= parameterEnd) {
+            return new vscode.Hover(`mom_${parameterMatch[1].replace(/^mom_/i, "")}`)
+        }
     }
+
     return undefined
 }