// Copyright (c) 2012- PPSSPP Project.

// 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, version 2.0 or later versions.

// 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 2.0 for more details.

// A copy of the GPL 2.0 should have been included with the program.
// If not, see http://www.gnu.org/licenses/

// Official git repository and contact information can be found at
// https://github.com/hrydgard/ppsspp and http://www.ppsspp.org/.

#include <set>

#include "base/NativeApp.h"
#include "base/display.h"
#include "base/mutex.h"
#include "base/timeutil.h"
#include "input/input_state.h"

#include "Core/Core.h"
#include "Core/Config.h"
#include "Core/MemMap.h"
#include "Core/SaveState.h"
#include "Core/System.h"
#include "Core/MIPS/MIPS.h"

#ifdef _WIN32
#ifndef _XBOX
#include "Windows/OpenGLBase.h"
#include "Windows/D3D9Base.h"
#endif
#include "Windows/InputDevice.h"
#endif

#include "Host.h"

#include "Core/Debugger/Breakpoints.h"

// Time until we stop considering the core active without user input.
// Should this be configurable?  2 hours currently.
static const double ACTIVITY_IDLE_TIMEOUT = 2.0 * 3600.0;

static event m_hStepEvent;
static recursive_mutex m_hStepMutex;
static event m_hInactiveEvent;
static recursive_mutex m_hInactiveMutex;
static bool singleStepPending = false;
static std::set<Core_ShutdownFunc> shutdownFuncs;
static bool windowHidden = false;
static double lastActivity = 0.0;
static double lastKeepAwake = 0.0;

#ifdef _WIN32
InputState input_state;
#else
extern InputState input_state;
#endif

void Core_NotifyWindowHidden(bool hidden) {
	windowHidden = hidden;
	// TODO: Wait until we can react?
}

void Core_NotifyActivity() {
	lastActivity = time_now_d();
}

void Core_ListenShutdown(Core_ShutdownFunc func) {
	shutdownFuncs.insert(func);
}

void Core_NotifyShutdown() {
	for (auto it = shutdownFuncs.begin(); it != shutdownFuncs.end(); ++it) {
		(*it)();
	}
}

void Core_ErrorPause() {
	Core_UpdateState(CORE_ERROR);
}

void Core_Halt(const char *msg)  {
	Core_EnableStepping(true);
	ERROR_LOG(CPU, "CPU HALTED : %s",msg);
	_dbg_update_();
}

void Core_Stop() {
	Core_UpdateState(CORE_POWERDOWN);
	Core_NotifyShutdown();
	m_hStepEvent.notify_one();
}

bool Core_IsStepping() {
	return coreState == CORE_STEPPING || coreState == CORE_POWERDOWN;
}

bool Core_IsActive() {
	return coreState == CORE_RUNNING || coreState == CORE_NEXTFRAME || coreStatePending;
}

bool Core_IsInactive() {
	return coreState != CORE_RUNNING && coreState != CORE_NEXTFRAME && !coreStatePending;
}

void Core_WaitInactive() {
	while (Core_IsActive()) {
		m_hInactiveEvent.wait(m_hInactiveMutex);
	}
}

void Core_WaitInactive(int milliseconds) {
	if (Core_IsActive()) {
		m_hInactiveEvent.wait_for(m_hInactiveMutex, milliseconds);
	}
}

bool UpdateScreenScale(int width, int height) {
	g_dpi = 72;
	g_dpi_scale = 1.0f;
#if defined(__SYMBIAN32__)
	g_dpi_scale = 1.4f;
#elif defined(_WIN32)
	if (width < 480 + 80) {
		g_dpi_scale = 2.0f;
	}
#endif
	pixel_in_dps = 1.0f / g_dpi_scale;

	int new_dp_xres = width * g_dpi_scale;
	int new_dp_yres = height * g_dpi_scale;

	bool dp_changed = new_dp_xres != dp_xres || new_dp_yres != dp_yres;
	bool px_changed = pixel_xres != width || pixel_yres != height;

	if (dp_changed || px_changed) {
		dp_xres = new_dp_xres;
		dp_yres = new_dp_yres;
		pixel_xres = width;
		pixel_yres = height;

		NativeResized();
		return true;
	}
	return false;
}

void UpdateRunLoop() {
	if (windowHidden && g_Config.bPauseWhenMinimized) {
		sleep_ms(16);
		return;
	}
	NativeUpdate(input_state);

	{
		lock_guard guard(input_state.lock);
		EndInputState(&input_state);
	}

	if (GetUIState() != UISTATE_EXIT) {
		NativeRender();
	}
}

#if defined(USING_WIN_UI)

void GPU_SwapBuffers() {
	switch (g_Config.iGPUBackend) {
	case GPU_BACKEND_OPENGL:
		GL_SwapBuffers();
		break;
	case GPU_BACKEND_DIRECT3D9:
		D3D9_SwapBuffers();
		break;
	}
}

#endif

void Core_RunLoop() {
	while ((GetUIState() != UISTATE_INGAME || !PSP_IsInited()) && GetUIState() != UISTATE_EXIT) {
		time_update();
#if defined(USING_WIN_UI)
		double startTime = time_now_d();
		UpdateRunLoop();

		// Simple throttling to not burn the GPU in the menu.
		time_update();
		double diffTime = time_now_d() - startTime;
		int sleepTime = (int)(1000.0 / 60.0) - (int)(diffTime * 1000.0);
		if (sleepTime > 0)
			Sleep(sleepTime);
		if (!windowHidden) {
			GPU_SwapBuffers();
		}
#else
		UpdateRunLoop();
#endif
	}

	while (!coreState && GetUIState() == UISTATE_INGAME) {
		time_update();
		UpdateRunLoop();
#if defined(USING_WIN_UI)
		if (!windowHidden && !Core_IsStepping()) {
			GPU_SwapBuffers();

			// Keep the system awake for longer than normal for cutscenes and the like.
			const double now = time_now_d();
			if (now < lastActivity + ACTIVITY_IDLE_TIMEOUT) {
				// Only resetting it ever prime number seconds in case the call is expensive.
				// Using a prime number to ensure there's no interaction with other periodic events.
				if (now - lastKeepAwake > 89.0 || now < lastKeepAwake) {
					SetThreadExecutionState(ES_SYSTEM_REQUIRED | ES_DISPLAY_REQUIRED);
					lastKeepAwake = now;
				}
			}
		}
#endif
	}
}

void Core_DoSingleStep() {
	singleStepPending = true;
	m_hStepEvent.notify_one();
}

void Core_UpdateSingleStep() {
	m_hStepEvent.notify_one();
}

void Core_SingleStep() {
	currentMIPS->SingleStep();
}

static inline void CoreStateProcessed() {
	if (coreStatePending) {
		coreStatePending = false;
		m_hInactiveEvent.notify_one();
	}
}

// Some platforms, like Android, do not call this function but handle things on their own.
void Core_Run()
{
#if defined(_DEBUG)
	host->UpdateDisassembly();
#endif
#if !defined(USING_QT_UI) || defined(MOBILE_DEVICE)
	while (true)
#endif
	{
reswitch:
		if (GetUIState() != UISTATE_INGAME) {
			CoreStateProcessed();
			if (GetUIState() == UISTATE_EXIT) {
				return;
			}
			Core_RunLoop();
#if defined(USING_QT_UI) && !defined(MOBILE_DEVICE)
			return;
#else
			continue;
#endif
		}

		switch (coreState)
		{
		case CORE_RUNNING:
			// enter a fast runloop
			Core_RunLoop();
			break;

		// We should never get here on Android.
		case CORE_STEPPING:
			singleStepPending = false;
			CoreStateProcessed();

			// Check if there's any pending savestate actions.
			SaveState::Process();
			if (coreState == CORE_POWERDOWN) {
				return;
			}

			// wait for step command..
#if defined(USING_QT_UI) || defined(_DEBUG)
			host->UpdateDisassembly();
			host->UpdateMemView();
			host->SendCoreWait(true);
#endif

			m_hStepEvent.wait(m_hStepMutex);

#if defined(USING_QT_UI) || defined(_DEBUG)
			host->SendCoreWait(false);
#endif
#if defined(USING_QT_UI) && !defined(MOBILE_DEVICE)
			if (coreState != CORE_STEPPING)
				return;
#endif
			// No step pending?  Let's go back to the wait.
			if (!singleStepPending || coreState != CORE_STEPPING) {
				if (coreState == CORE_POWERDOWN) {
					return;
				}
				goto reswitch;
			}

			Core_SingleStep();
			// update disasm dialog
#if defined(USING_QT_UI) || defined(_DEBUG)
			host->UpdateDisassembly();
			host->UpdateMemView();
#endif
			break;

		case CORE_POWERUP:
		case CORE_POWERDOWN:
		case CORE_ERROR:
			// Exit loop!!
			CoreStateProcessed();

			return;

		case CORE_NEXTFRAME:
			return;
		}
	}

}


void Core_EnableStepping(bool step) {
	if (step) {
		sleep_ms(1);
#if defined(_DEBUG)
		host->SetDebugMode(true);
#endif
		m_hStepEvent.reset();
		Core_UpdateState(CORE_STEPPING);
	} else {
#if defined(_DEBUG)
		host->SetDebugMode(false);
#endif
		coreState = CORE_RUNNING;
		coreStatePending = false;
		m_hStepEvent.notify_one();
	}
}