/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.

 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.

 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * $URL$
 * $Id$
 *
 */

#include "common/system.h"

#include "sci/sci.h"
#include "sci/debug.h"
#include "sci/engine/state.h"
#include "sci/engine/kernel.h"
#include "sci/engine/gc.h"
#include "sci/gui/gui.h"

namespace Sci {

reg_t kRestartGame(EngineState *s, int argc, reg_t *argv) {
	s->restarting_flags |= SCI_GAME_IS_RESTARTING_NOW;
	s->restarting_flags &= ~SCI_GAME_WAS_RESTARTED_AT_LEAST_ONCE; // This appears to help

	shrink_execution_stack(s, s->execution_stack_base + 1);

	script_abort_flag = 1; // Force vm to abort ASAP
	return NULL_REG;
}

/* kGameIsRestarting():
** Returns the restarting_flag in acc
*/
reg_t kGameIsRestarting(EngineState *s, int argc, reg_t *argv) {
	s->r_acc = make_reg(0, (s->restarting_flags & SCI_GAME_WAS_RESTARTED));

	if (argc) { // Only happens during replay
		if (!argv[0].toUint16()) // Set restarting flag
			s->restarting_flags &= ~SCI_GAME_WAS_RESTARTED;
	}

	return s->r_acc;
}

reg_t kHaveMouse(EngineState *s, int argc, reg_t *argv) {
	return SIGNAL_REG;
}

enum kMemoryInfoFunc {
	K_MEMORYINFO_LARGEST_HEAP_BLOCK = 0, // Largest heap block available
	K_MEMORYINFO_FREE_HEAP = 1, // Total free heap memory
	K_MEMORYINFO_LARGEST_HUNK_BLOCK = 2, // Largest available hunk memory block
	K_MEMORYINFO_FREE_HUNK = 3, // Amount of free DOS paragraphs
	K_MEMORYINFO_TOTAL_HUNK = 4 // Total amount of hunk memory (SCI01)
};

reg_t kMemoryInfo(EngineState *s, int argc, reg_t *argv) {
	const uint16 size = 0x7fff;  // Must not be 0xffff, or some memory calculations will overflow

	switch (argv[0].offset) {
	case K_MEMORYINFO_LARGEST_HEAP_BLOCK:
		// In order to prevent "Memory fragmented" dialogs from
		// popping up in some games, we must return FREE_HEAP - 2 here.
		return make_reg(0, size - 2);
	case K_MEMORYINFO_FREE_HEAP:
	case K_MEMORYINFO_LARGEST_HUNK_BLOCK:
	case K_MEMORYINFO_FREE_HUNK:
	case K_MEMORYINFO_TOTAL_HUNK:
		return make_reg(0, size);

	default:
		warning("Unknown MemoryInfo operation: %04x", argv[0].offset);
	}

	return NULL_REG;
}

reg_t kFlushResources(EngineState *s, int argc, reg_t *argv) {
	run_gc(s);
	debugC(2, kDebugLevelRoom, "Entering room number %d", argv[0].toUint16());
	return s->r_acc;
}

reg_t kSetDebug(EngineState *s, int argc, reg_t *argv) {
	printf("Debug mode activated\n");

	g_debugState.seeking = kDebugSeekNothing;
	g_debugState.runningStep = 0;
	return s->r_acc;
}

enum {
	K_NEW_GETTIME_TICKS = 0,
	K_NEW_GETTIME_TIME_12HOUR = 1,
	K_NEW_GETTIME_TIME_24HOUR = 2,
	K_NEW_GETTIME_DATE = 3
};

reg_t kGetTime(EngineState *s, int argc, reg_t *argv) {
	TimeDate loc_time;
	uint32 elapsedTime;
	int retval = 0; // Avoid spurious warning

	g_system->getTimeAndDate(loc_time);
	elapsedTime = g_system->getMillis() - s->game_start_time;

	if ((s->_flags & GF_SCI0_OLDGETTIME) && argc) { // Use old semantics
		retval = (loc_time.tm_hour % 12) * 3600 + loc_time.tm_min * 60 + loc_time.tm_sec;
		debugC(2, kDebugLevelTime, "GetTime(timeofday) returns %d", retval);
		return make_reg(0, retval);
	}

	int mode = (argc > 0) ? argv[0].toUint16() : 0;

	switch (mode) {
	case K_NEW_GETTIME_TICKS :
		retval = elapsedTime * 60 / 1000;
		debugC(2, kDebugLevelTime, "GetTime(elapsed) returns %d", retval);
		break;
	case K_NEW_GETTIME_TIME_12HOUR :
		retval = ((loc_time.tm_hour % 12) << 12) | (loc_time.tm_min << 6) | (loc_time.tm_sec);
		debugC(2, kDebugLevelTime, "GetTime(12h) returns %d", retval);
		break;
	case K_NEW_GETTIME_TIME_24HOUR :
		retval = (loc_time.tm_hour << 11) | (loc_time.tm_min << 5) | (loc_time.tm_sec >> 1);
		debugC(2, kDebugLevelTime, "GetTime(24h) returns %d", retval);
		break;
	case K_NEW_GETTIME_DATE :
		retval = loc_time.tm_mday | ((loc_time.tm_mon + 1) << 5) | (((loc_time.tm_year + 1900) & 0x7f) << 9);
		debugC(2, kDebugLevelTime, "GetTime(date) returns %d", retval);
		break;
	default:
		warning("Attempt to use unknown GetTime mode %d", mode);
		break;
	}

	return make_reg(0, retval);
}

enum {
	K_MEMORY_ALLOCATE_CRITICAL		= 1,
	K_MEMORY_ALLOCATE_NONCRITICAL   = 2,
	K_MEMORY_FREE					= 3,
	K_MEMORY_MEMCPY					= 4,
	K_MEMORY_PEEK					= 5,
	K_MEMORY_POKE					= 6
};

reg_t kMemory(EngineState *s, int argc, reg_t *argv) {
	switch (argv[0].toUint16()) {
	case K_MEMORY_ALLOCATE_CRITICAL :
		if (!s->_segMan->allocDynmem(argv[1].toUint16(), "kMemory() critical", &s->r_acc)) {
			error("Critical heap allocation failed");
		}
		break;
	case K_MEMORY_ALLOCATE_NONCRITICAL :
		s->_segMan->allocDynmem(argv[1].toUint16(), "kMemory() non-critical", &s->r_acc);
		break;
	case K_MEMORY_FREE :
		if (s->_segMan->freeDynmem(argv[1])) {
			error("Attempt to kMemory::free() non-dynmem pointer %04x:%04x", PRINT_REG(argv[1]));
		}
		break;
	case K_MEMORY_MEMCPY : {
		int size = argv[3].toUint16();
		s->_segMan->memcpy(argv[1], argv[2], size);
		break;
	}
	case K_MEMORY_PEEK : {
		SegmentRef ref = s->_segMan->dereference(argv[1]);

		if (!ref.isValid() || ref.maxSize < 2) {
			// This occurs in KQ5CD when interacting with certain objects
			warning("Attempt to peek invalid memory at %04x:%04x", PRINT_REG(argv[1]));
			return s->r_acc;
		}
		if (ref.isRaw)
			return make_reg(0, (int16)READ_LE_UINT16(ref.raw));
		else
			return *(ref.reg);
		break;
	}
	case K_MEMORY_POKE : {
		SegmentRef ref = s->_segMan->dereference(argv[1]);

		if (!ref.isValid() || ref.maxSize < 2) {
			warning("Attempt to poke invalid memory at %04x:%04x", PRINT_REG(argv[1]));
			return s->r_acc;
		}

		if (ref.isRaw) {
			if (argv[2].segment) {
				error("Attempt to poke memory reference %04x:%04x to %04x:%04x", PRINT_REG(argv[2]), PRINT_REG(argv[1]));
				return s->r_acc;
			}
			WRITE_LE_UINT16(ref.raw, argv[2].offset);
		} else
			*(ref.reg) = argv[2];
		break;
	}
	}

	return s->r_acc;
}

reg_t kPlatform(EngineState *s, int argc, reg_t *argv) {
	if (argc == 1) {
		if (argv[0].toUint16() == 4)
			if (((SciEngine*)g_engine)->getPlatform() == Common::kPlatformWindows)
				return make_reg(0, 2);
			else
				return make_reg(0, 1);
		else if (argv[0].toUint16() == 5)
			warning("kPlatform(5)"); // TODO: return 1 based on some variable
		else if (argv[0].toUint16() == 6)
			warning("kPlatform(6)"); // TODO: return some variable
		else if (argv[0].toUint16() == 7 && ((SciEngine*)g_engine)->getPlatform() == Common::kPlatformWindows)
			return make_reg(0, 1);
	}
	
	return NULL_REG;
}

} // End of namespace Sci