#include <limits.h>
#include <algorithm>

#include "base/NativeApp.h"
#include "Core/Config.h"
#include "Common/KeyMap.h"
#include "input/input_state.h"
#include "input/keycodes.h"
#include "XinputDevice.h"

// Utilities to dynamically load XInput. Adapted from SDL.

typedef DWORD (WINAPI *XInputGetState_t) (DWORD dwUserIndex, XINPUT_STATE* pState);
typedef DWORD (WINAPI *XInputSetState_t) (DWORD dwUserIndex, XINPUT_VIBRATION* pVibration);
typedef DWORD (WINAPI *XInputGetCapabilities_t) (DWORD dwUserIndex, DWORD dwFlags, XINPUT_CAPABILITIES* pCapabilities);

XInputGetState_t PPSSPP_XInputGetState = NULL;
XInputSetState_t PPSSPP_XInputSetState = NULL;
XInputGetCapabilities_t PPSSPP_XInputGetCapabilities = NULL;
static DWORD PPSSPP_XInputVersion = 0;
static HMODULE s_pXInputDLL = 0;
static int s_XInputDLLRefCount = 0;

static void UnloadXInputDLL();

static int LoadXInputDLL() {
	DWORD version = 0;

	if (s_pXInputDLL) {
		s_XInputDLLRefCount++;
		return 0;  /* already loaded */
	}

	version = (1 << 16) | 4;
	s_pXInputDLL = LoadLibrary( L"XInput1_4.dll" );  // 1.4 Ships with Windows 8.
	if (!s_pXInputDLL) {
		version = (1 << 16) | 3;
		s_pXInputDLL = LoadLibrary( L"XInput1_3.dll" );  // 1.3 Ships with Vista and Win7, can be installed as a restributable component.
	}
	if (!s_pXInputDLL) {
		return -1;
	}

	PPSSPP_XInputVersion = version;
	s_XInputDLLRefCount = 1;

	/* 100 is the ordinal for _XInputGetStateEx, which returns the same struct as XinputGetState, but with extra data in wButtons for the guide button, we think... */
	PPSSPP_XInputGetState = (XInputGetState_t)GetProcAddress( (HMODULE)s_pXInputDLL, (LPCSTR)100 );
	PPSSPP_XInputSetState = (XInputSetState_t)GetProcAddress( (HMODULE)s_pXInputDLL, "XInputSetState" );
	PPSSPP_XInputGetCapabilities = (XInputGetCapabilities_t)GetProcAddress( (HMODULE)s_pXInputDLL, "XInputGetCapabilities" );
	if ( !PPSSPP_XInputGetState || !PPSSPP_XInputSetState || !PPSSPP_XInputGetCapabilities ) {
		UnloadXInputDLL();
		return -1;
	}

	return 0;
}

static void UnloadXInputDLL() {
	if ( s_pXInputDLL ) {
		if (--s_XInputDLLRefCount == 0) {
			FreeLibrary( s_pXInputDLL );
			s_pXInputDLL = NULL;
		}
	}
}

#ifndef XUSER_MAX_COUNT
#define XUSER_MAX_COUNT 4
#endif

// Undocumented. Steam annoyingly grabs this button though....
#define XINPUT_GUIDE_BUTTON 0x400


// Permanent map. Actual mapping happens elsewhere.
static const struct {int from, to;} xinput_ctrl_map[] = {
	{XINPUT_GAMEPAD_A,              NKCODE_BUTTON_A},
	{XINPUT_GAMEPAD_B,              NKCODE_BUTTON_B},
	{XINPUT_GAMEPAD_X,              NKCODE_BUTTON_X},
	{XINPUT_GAMEPAD_Y,              NKCODE_BUTTON_Y},
	{XINPUT_GAMEPAD_BACK,           NKCODE_BUTTON_SELECT},
	{XINPUT_GAMEPAD_START,          NKCODE_BUTTON_START},
	{XINPUT_GAMEPAD_LEFT_SHOULDER,  NKCODE_BUTTON_L1},
	{XINPUT_GAMEPAD_RIGHT_SHOULDER, NKCODE_BUTTON_R1},
	{XINPUT_GAMEPAD_LEFT_THUMB,     NKCODE_BUTTON_THUMBL},
	{XINPUT_GAMEPAD_RIGHT_THUMB,    NKCODE_BUTTON_THUMBR},
	{XINPUT_GAMEPAD_DPAD_UP,        NKCODE_DPAD_UP},
	{XINPUT_GAMEPAD_DPAD_DOWN,      NKCODE_DPAD_DOWN},
	{XINPUT_GAMEPAD_DPAD_LEFT,      NKCODE_DPAD_LEFT},
	{XINPUT_GAMEPAD_DPAD_RIGHT,     NKCODE_DPAD_RIGHT},
	{XINPUT_GUIDE_BUTTON,           NKCODE_HOME},
};

static const unsigned int xinput_ctrl_map_size = sizeof(xinput_ctrl_map) / sizeof(xinput_ctrl_map[0]);

XinputDevice::XinputDevice() {
	if (LoadXInputDLL() != 0) {
		ERROR_LOG(SCECTRL, "Failed to load XInput! DLL missing");
	}
	ZeroMemory( &this->prevState, sizeof(this->prevState) );
	this->check_delay = 0;
	this->gamepad_idx = -1;
}

XinputDevice::~XinputDevice() {
	UnloadXInputDLL();
}

struct Stick {
	Stick (float x_, float y_, float scale) : x(x_ * scale), y(y_ * scale) {}
	float x;
	float y;
};

inline float Clampf(float val, float min, float max) {
	if (val < min) return min;
	if (val > max) return max;
	return val;
}

inline float Signf(float val) {
	return (0.0f < val) - (val < 0.0f);
}

inline float LinearMapf(float val, float a0, float a1, float b0, float b1) {
	return b0 + (((val - a0) * (b1 - b0)) / (a1 - a0));
}

static Stick NormalizedDeadzoneFilter(short x, short y, float dz, int idzm, float idz, float st) {
	Stick s(x, y, 1.0 / 32767.0f);

	float magnitude = sqrtf(s.x * s.x + s.y * s.y);
	if (magnitude > dz) {

		// Circle to square mapping (the PSP stick outputs the full -1..1 square of values)
#if 1
		// Looks way better than the old one, below, in the axis tester.
		float sx = s.x;
		float sy = s.y;
		float scaleFactor = sqrtf((sx * sx + sy * sy) / std::max(sx * sx, sy * sy));
		s.x = sx * scaleFactor;
		s.y = sy * scaleFactor;
#else
		if (magnitude > 1.0f) {
			s.x *= 1.41421f;
			s.y *= 1.41421f;
		}
#endif

		// Linear range mapping (used to invert deadzones)
		float md = std::max(dz, idz);

		if (idzm == 1)
		{
			float xSign = Signf(s.x);
			if (xSign != 0.0f) {
				s.x = LinearMapf(s.x, xSign * dz, xSign, xSign * md, xSign * st);
			}
		}
		else if (idzm == 2)
		{
			float ySign = Signf(s.y);
			if (ySign != 0.0f) {
				s.y = LinearMapf(s.y, ySign * dz, ySign, ySign * md, ySign * st);
			}
		}
		else if (idzm == 3)
		{
			float xNorm = s.x / magnitude;
			float yNorm = s.y / magnitude;
			float mapMag = LinearMapf(magnitude, dz, 1.0f, md, st);
			s.x = xNorm * mapMag;
			s.y = yNorm * mapMag;
		}

		s.x = Clampf(s.x, -1.0f, 1.0f);
		s.y = Clampf(s.y, -1.0f, 1.0f);
	} else {
		s.x = 0.0f;
		s.y = 0.0f;
	}
	return s;
}

bool NormalizedDeadzoneDiffers(short x1, short y1, short x2, short y2, const float dz) {
	Stick s1(x1, y1, 1.0 / 32767.0f);
	Stick s2(x2, y2, 1.0 / 32767.0f);

	float magnitude1 = sqrtf(s1.x * s1.x + s1.y * s1.y);
	float magnitude2 = sqrtf(s2.x * s2.x + s2.y * s2.y);
	if (magnitude1 > dz || magnitude2 > dz) {
		return x1 != x2 || y1 != y2;
	}
	return false;
}

bool NormalizedDeadzoneDiffers(u8 x1, u8 x2, const u8 thresh) {
	if (x1 > thresh || x2 > thresh) {
		return x1 != x2;
	}
	return false;
}

int XinputDevice::UpdateState(InputState &input_state) {
	if (!s_pXInputDLL)
		return 0;

	if (this->check_delay-- > 0)
		return -1;

	XINPUT_STATE state;
	ZeroMemory( &state, sizeof(XINPUT_STATE) );

	DWORD dwResult;
	if (this->gamepad_idx >= 0) {
		dwResult = PPSSPP_XInputGetState( this->gamepad_idx, &state );
	} else {
		// use the first gamepad that responds
		for (int i = 0; i < XUSER_MAX_COUNT; i++) {
			dwResult = PPSSPP_XInputGetState( i, &state );
			if (dwResult == ERROR_SUCCESS) {
				this->gamepad_idx = i;
				break;
			}
		}
	}
	
	if ( dwResult == ERROR_SUCCESS ) {
		static bool notified = false;
		if (!notified) {
			notified = true;
			KeyMap::NotifyPadConnected("Xbox 360 Pad");
		}
		ApplyButtons(state, input_state);

		const float STICK_DEADZONE = g_Config.fXInputAnalogDeadzone;
		const int STICK_INV_MODE = g_Config.iXInputAnalogInverseMode;
		const float STICK_INV_DEADZONE = g_Config.fXInputAnalogInverseDeadzone;
		const float STICK_SENSITIVITY = g_Config.fXInputAnalogSensitivity;

		if (NormalizedDeadzoneDiffers(prevState.Gamepad.sThumbLX, prevState.Gamepad.sThumbLY, state.Gamepad.sThumbLX, state.Gamepad.sThumbLY, STICK_DEADZONE)) {
			Stick left = NormalizedDeadzoneFilter(state.Gamepad.sThumbLX, state.Gamepad.sThumbLY, STICK_DEADZONE, STICK_INV_MODE, STICK_INV_DEADZONE, STICK_SENSITIVITY);

			AxisInput axis;
			axis.deviceId = DEVICE_ID_X360_0;
			axis.axisId = JOYSTICK_AXIS_X;
			axis.value = left.x;
			if (prevState.Gamepad.sThumbLX != state.Gamepad.sThumbLX) {
				NativeAxis(axis);
			}
			axis.axisId = JOYSTICK_AXIS_Y;
			axis.value = left.y;
			if (prevState.Gamepad.sThumbLY != state.Gamepad.sThumbLY) {
				NativeAxis(axis);
			}
		}

		if (NormalizedDeadzoneDiffers(prevState.Gamepad.sThumbRX, prevState.Gamepad.sThumbRY, state.Gamepad.sThumbRX, state.Gamepad.sThumbRY, STICK_DEADZONE)) {
			Stick right = NormalizedDeadzoneFilter(state.Gamepad.sThumbRX, state.Gamepad.sThumbRY, STICK_DEADZONE, STICK_INV_MODE, STICK_INV_DEADZONE, STICK_SENSITIVITY);

			AxisInput axis;
			axis.deviceId = DEVICE_ID_X360_0;
			axis.axisId = JOYSTICK_AXIS_Z;
			axis.value = right.x;
			if (prevState.Gamepad.sThumbRX != state.Gamepad.sThumbRX) {
				NativeAxis(axis);
			}
			axis.axisId = JOYSTICK_AXIS_RZ;
			axis.value = right.y;
			if (prevState.Gamepad.sThumbRY != state.Gamepad.sThumbRY) {
				NativeAxis(axis);
			}
		}

		if (NormalizedDeadzoneDiffers(prevState.Gamepad.bLeftTrigger, state.Gamepad.bLeftTrigger, XINPUT_GAMEPAD_TRIGGER_THRESHOLD)) {
			AxisInput axis;
			axis.deviceId = DEVICE_ID_X360_0;
			axis.axisId = JOYSTICK_AXIS_LTRIGGER;
			axis.value = (float)state.Gamepad.bLeftTrigger / 255.0f;
			NativeAxis(axis);
		}

		if (NormalizedDeadzoneDiffers(prevState.Gamepad.bRightTrigger, state.Gamepad.bRightTrigger, XINPUT_GAMEPAD_TRIGGER_THRESHOLD)) {
			AxisInput axis;
			axis.deviceId = DEVICE_ID_X360_0;
			axis.axisId = JOYSTICK_AXIS_RTRIGGER;
			axis.value = (float)state.Gamepad.bRightTrigger / 255.0f;
			NativeAxis(axis);
		}

		this->prevState = state;
		this->check_delay = 0;

		// If there's an XInput pad, skip following pads. This prevents DInput and XInput
		// from colliding.
		return UPDATESTATE_SKIP_PAD;
	} else {
		// wait check_delay frames before polling the controller again
		this->gamepad_idx = -1;
		this->check_delay = 100;
		return -1;
	}
}

void XinputDevice::ApplyButtons(XINPUT_STATE &state, InputState &input_state) {
	u32 buttons = state.Gamepad.wButtons;

	u32 downMask = buttons & (~prevButtons);
	u32 upMask = (~buttons) & prevButtons;
	prevButtons = buttons;
	
	for (int i = 0; i < xinput_ctrl_map_size; i++) {
		if (downMask & xinput_ctrl_map[i].from) {
			KeyInput key;
			key.deviceId = DEVICE_ID_X360_0;
			key.flags = KEY_DOWN;
			key.keyCode = xinput_ctrl_map[i].to;
			NativeKey(key);
		}
		if (upMask & xinput_ctrl_map[i].from) {
			KeyInput key;
			key.deviceId = DEVICE_ID_X360_0;
			key.flags = KEY_UP;
			key.keyCode = xinput_ctrl_map[i].to;
			NativeKey(key);
		}
	}
}