/* ILEngineer - Crummy .NET Decompiler
 * Copyright (C) 2001-2002  Jay Freeman (saurik)
*/

/*
 *        Redistribution and use in source and binary
 * forms, with or without modification, are permitted
 * provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the
 *    above copyright notice, this list of conditions
 *    and the following disclaimer.
 * 2. 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.
 * 3. The name of the author may not be used to endorse
 *    or promote products derived from this software
 *    without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE 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 THE 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 "stdafx.h"
#include "ilengineer/Block.h"

#include "ilengineer/Blocks/Case.h"
#include "ilengineer/Blocks/Default.h"
#include "ilengineer/Blocks/Method.h"
#include "ilengineer/Blocks/Switch.h"

#include "ilengineer/Ops/MSIL/Branch.h"
#include "ilengineer/Ops/MSIL/LoadConstant.h"

void ILEngineer::Block::OptimizeSwitch() {
	for (StatementVector::iterator stI(m_Statements.begin()); stI != m_Statements.end(); stI++) {
		if ((*stI)->isBlock())
			dynamic_cast<Block *>(*stI)->OptimizeSwitch();
		else {
			Ops::MSIL::Switch *sweet = dynamic_cast<Ops::MSIL::Switch *>((*stI)->getOperations()[0]);
			if (sweet != NULL) {
				Blocks::Switch *sweep = new Blocks::Switch(m_Method, sweet);
				Ops::MSIL::Switch::TargetMap &targets = sweet->getTargets();
				*(stI++) = sweep;

				Ops::MSIL::Switch::TargetMap::iterator local, remote(targets.begin());
				std::pair<Ops::MSIL::Switch::TargetMap::iterator, Ops::MSIL::Switch::TargetMap::iterator> range;
				Block *debter = new Blocks::Default(m_Method);

				uint8_t *bad = NULL;
				bool first(true);

				do {
					Block *block;

					if (first)
						block = debter;
					else {
						range = targets.equal_range(local->first);
						remote = range.second;
						if (local->first == bad)
							continue;

						Blocks::Case *castor = new Blocks::Case(m_Method);
						for (Ops::MSIL::Switch::TargetMap::iterator tmI(range.first); tmI != range.second; tmI++)
							castor->Tack(new Ops::MSIL::LoadU4Constant(m_Method, NULL, tmI->second));
						sweep->getStatements().push_back(block = castor);
					}

					if (remote != targets.end()) {
						while ((*stI)->getOffset() != remote->first) {
							block->getStatements().push_back(*stI);
							if (stI >= m_Statements.end())
								throw std::wstring(L"malformed switch statement");
							m_Statements.erase(stI);
						}
						block->setEnd(remote->first);
					} else if (bad != NULL) {
						while ((*stI)->getOffset() != bad) {
							block->getStatements().push_back(*stI);
							m_Statements.erase(stI);
						}
						block->setEnd(bad);
					} else {
						while (stI != m_Statements.end()) {
							block->getStatements().push_back(*stI);
							m_Statements.erase(stI);
						}
						block->setEnd(m_End);
					}

					if (first) {
						first = false;
						if (debter->getStatements().size() != 0) {
							Statement *st = debter->getStatements().back();
							if (!st->isBlock()) {
								Ops::MSIL::Branch *branch = dynamic_cast<Ops::MSIL::Branch *>(st->getOperations()[0]);
								if (branch != NULL && (remote == targets.end() || branch->getTarget() > remote->first)) {
									bad = branch->getTarget();
									if (debter->getStatements().size() == 1) {
										delete debter;
										debter = NULL;
									}
								}
							}
						}
					}
				} while ((local = remote) != targets.end());

				if (debter != NULL && debter->getStatements().size() != 0)
					sweep->getStatements().push_back(debter);
				sweep->OptimizeSwitch();
				sweep->setEnd((stI == m_Statements.end()) ? m_End : (*stI)->getOffset());
				delete sweet;
				stI--;
			}
		}
	}
}