/*
 * Copyright (c) 2007-2015 University of Illinois at Urbana-Champaign.
 * Copyright (c) 2015, Vsevolod Stakhov
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *	 * Redistributions of source code must retain the above copyright
 *	   notice, this list of conditions and the following disclaimer.
 *	 * Redistributions in binary form must reproduce the above copyright
 *	   notice, this list of conditions and the following disclaimer in the
 *	   documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY AUTHOR ''AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL AUTHOR BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */


#include "clang/Frontend/FrontendPluginRegistry.h"
#include "clang/AST/AST.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ASTConsumer.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/Frontend/CompilerInstance.h"
#include "clang/Sema/Sema.h"
#include "llvm/Support/raw_ostream.h"
#include <unordered_map>

using namespace clang;

namespace {

	class RspamdASTConsumer : public ASTConsumer {
		CompilerInstance &Instance;

	public:
		RspamdASTConsumer (CompilerInstance &Instance)
				: Instance (Instance)
		{
		}

		void HandleTranslationUnit (ASTContext &context) override
		{
			struct Visitor : public RecursiveASTVisitor<Visitor> {
				std::unordered_map<std::string, int> printf_functions;
				ASTContext *pcontext;

				Visitor (void)
				{
					/* name -> format string position */
					printf_functions = {
							{"rspamd_printf", 0},
							{"rspamd_default_log_function", 4},
							{"rspamd_snprintf", 2},
							{"rspamd_fprintf", 1}
					};
				};

				bool VisitCallExpr (CallExpr *E)
				{
					auto callee = dyn_cast<NamedDecl> (E->getCalleeDecl ());
					if (callee == NULL) {
						llvm::errs () << "Bad callee\n";
						return false;
					}

					auto fname = callee->getNameAsString ();

					auto pos_it = printf_functions.find (fname);

					if (pos_it != printf_functions.end ()) {
						const auto args = E->getArgs ();
						auto pos = pos_it->second;
						auto query = args[pos];

						if (!query->isEvaluatable(*pcontext)) {
							llvm::errs () << "Cannot evaluate query\n";
							return false;
						}

						clang::Expr::EvalResult r;

						if (!query->EvaluateAsRValue (r, *pcontext)) {
							llvm::errs () << "Cannot evaluate query\n";
							return false;
						}

						auto qval = dyn_cast<StringLiteral> (
								r.Val.getLValueBase ().get<const Expr *> ());
						if (qval) {
							llvm::errs () << "query string: "
									<< qval->getString () << "\n";
						}

						for (auto i = pos + 1; i < E->getNumArgs (); i ++) {
							auto arg = args[i];

							if (arg) {
								arg->dump ();
							}
						}
					}

					return true;
				}

			} v;
			v.pcontext = &context;
			v.TraverseDecl (context.getTranslationUnitDecl ());
		}
	};

	class RspamdASTAction : public PluginASTAction {
	protected:
		std::unique_ptr <ASTConsumer> CreateASTConsumer (CompilerInstance &CI,
				llvm::StringRef) override
		{
			return llvm::make_unique<RspamdASTConsumer> (CI);
		}

		bool ParseArgs (const CompilerInstance &CI,
				const std::vector <std::string> &args) override
		{
			return true;
		}

		void PrintHelp (llvm::raw_ostream &ros)
		{
			ros << "Nothing here\n";
		}

	};

}

static FrontendPluginRegistry::Add <RspamdASTAction>
		X ("rspamd-ast", "rspamd ast checker");