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// Copyright (c) 2026 Cloudflare, Inc.
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// Licensed under the Apache 2.0 license found in the LICENSE file or at:
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//     https://opensource.org/licenses/Apache-2.0
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import ts from "typescript";
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export function createAddOnMessageDeclarationTransformer(): ts.TransformerFactory<ts.SourceFile> {
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  return (context) => {
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    return (sourceFile) => {
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      // Create the new variable declaration
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      const onMessageDeclaration = context.factory.createVariableStatement(
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        [context.factory.createModifier(ts.SyntaxKind.DeclareKeyword)],
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        context.factory.createVariableDeclarationList(
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          [
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            context.factory.createVariableDeclaration(
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              "onmessage",
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              undefined,
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              context.factory.createKeywordTypeNode(ts.SyntaxKind.NeverKeyword)
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            ),
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          ],
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          ts.NodeFlags.None
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        )
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      );
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      // Prepend the new declaration to the source file
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      const updatedStatements = ts.factory.createNodeArray([
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        onMessageDeclaration,
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        ...sourceFile.statements,
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      ]);
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      // Return the updated source file
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      return ts.factory.updateSourceFile(sourceFile, updatedStatements);
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    };
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  };
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}