/*
 * OpenHMD - Free and Open Source API and drivers for immersive technology.
 * Copyright (C) 2013 Fredrik Hultin.
 * Copyright (C) 2013 Jakob Bornecrantz.
 * Distributed under the Boost 1.0 licence, see LICENSE for full text.
 */

/* Oculus Rift Driver - HID/USB Driver Implementation */

#include <stdlib.h>
#include <hidapi.h>
#include <string.h>
#include <stdio.h>
#include <time.h>
#include <assert.h>

#include "rift.h"

#define TICK_LEN (1.0f / 1000.0f) // 1000 Hz ticks
#define KEEP_ALIVE_VALUE (10 * 1000)
#define SETFLAG(_s, _flag, _val) (_s) = ((_s) & ~(_flag)) | ((_val) ? (_flag) : 0)


typedef struct {
	ohmd_device base;

	hid_device* handle;
	pkt_sensor_range sensor_range;
	pkt_sensor_display_info display_info;
	rift_coordinate_frame coordinate_frame, hw_coordinate_frame;
	pkt_sensor_config sensor_config;
	pkt_tracker_sensor sensor;
	double last_keep_alive;
	fusion sensor_fusion;
	vec3f raw_mag, raw_accel, raw_gyro;

	// These values are derived from the display_info struct and
	// from user provided values.
	struct {
		float idp; // inter-pupillary distance, user provided.

		float znear; // depth near value, user provided.
		float zfar; // depth far value, user provided.

		float proj_offset; // lens offset on screen
		mat4x4f proj_base; // base projection matrix
		mat4x4f proj_left; // adjusted projection matrix for left screen
		mat4x4f proj_right; // adjusted projection matrix for right screen

		float full_ratio; // screen ratio for the entire device

		float stereo_fov; // horizontal fov for one sub screen
		float stereo_ratio; // screen ratio for one sub screen
	} calc_values;
} rift_priv;

static rift_priv* rift_priv_get(ohmd_device* device)
{
	return (rift_priv*)device;
}


static int get_feature_report(rift_priv* priv, rift_sensor_feature_cmd cmd, unsigned char* buf)
{
	memset(buf, 0, FEATURE_BUFFER_SIZE);
	buf[0] = (unsigned char)cmd;
	return hid_get_feature_report(priv->handle, buf, FEATURE_BUFFER_SIZE);
}

static int send_feature_report(rift_priv* priv, const unsigned char *data, size_t length)
{
	return hid_send_feature_report(priv->handle, data, length);
}

static void set_coordinate_frame(rift_priv* priv, rift_coordinate_frame coordframe)
{
	priv->coordinate_frame = coordframe;

	// set the RIFT_SCF_SENSOR_COORDINATES in the sensor config to match whether coordframe is hmd or sensor
	SETFLAG(priv->sensor_config.flags, RIFT_SCF_SENSOR_COORDINATES, coordframe == RIFT_CF_SENSOR);

	// encode send the new config to the Rift 
	unsigned char buf[FEATURE_BUFFER_SIZE];
	int size = encode_sensor_config(buf, &priv->sensor_config);
	if(send_feature_report(priv, buf, size) == -1){
		ohmd_set_error(priv->base.ctx, "send_feature_report failed in set_coordinate frame");
		return;
	}

	// read the state again, set the hw_coordinate_frame to match what
	// the hardware actually is set to just incase it doesn't stick.
	size = get_feature_report(priv, RIFT_CMD_SENSOR_CONFIG, buf);
	if(size <= 0){
		LOGW("could not set coordinate frame");
		priv->hw_coordinate_frame = RIFT_CF_HMD;
		return;
	}

	decode_sensor_config(&priv->sensor_config, buf, size);
	priv->hw_coordinate_frame = (priv->sensor_config.flags & RIFT_SCF_SENSOR_COORDINATES) ? RIFT_CF_SENSOR : RIFT_CF_HMD;

	if(priv->hw_coordinate_frame != coordframe) {
		LOGW("coordinate frame didn't stick");
	}
}

static void handle_tracker_sensor_msg(rift_priv* priv, unsigned char* buffer, int size)
{
	if(!decode_tracker_sensor_msg(&priv->sensor, buffer, size)){
		LOGE("couldn't decode tracker sensor message");
	}

	pkt_tracker_sensor* s = &priv->sensor;

	dump_packet_tracker_sensor(s);

	// TODO handle missed samples etc.

	float dt = s->num_samples > 3 ? (s->num_samples - 2) * TICK_LEN : TICK_LEN;

	int32_t mag32[] = { s->mag[0], s->mag[1], s->mag[2] };
	vec3f_from_rift_vec(mag32, &priv->raw_mag);

	for(int i = 0; i < OHMD_MIN(s->num_samples, 3); i++){
		vec3f_from_rift_vec(s->samples[i].accel, &priv->raw_accel);
		vec3f_from_rift_vec(s->samples[i].gyro, &priv->raw_gyro);

		ofusion_update(&priv->sensor_fusion, dt, &priv->raw_gyro, &priv->raw_accel, &priv->raw_mag);

		// reset dt to tick_len for the last samples if there were more than one sample
		dt = TICK_LEN;
	}
}

static void update_device(ohmd_device* device)
{
	rift_priv* priv = rift_priv_get(device);
	unsigned char buffer[FEATURE_BUFFER_SIZE];

	// Handle keep alive messages
	double t = ohmd_get_tick();
	if(t - priv->last_keep_alive >= (double)priv->sensor_config.keep_alive_interval / 1000.0 - .2){
		// send keep alive message
		pkt_keep_alive keep_alive = { 0, priv->sensor_config.keep_alive_interval };
		int ka_size = encode_keep_alive(buffer, &keep_alive);
		send_feature_report(priv, buffer, ka_size);

		// Update the time of the last keep alive we have sent.
		priv->last_keep_alive = t;
	}

	// Read all the messages from the device.
	while(true){
		int size = hid_read(priv->handle, buffer, FEATURE_BUFFER_SIZE);
		if(size < 0){
			LOGE("error reading from device");
			return;
		} else if(size == 0) {
			return; // No more messages, return.
		}

		// currently the only message type the hardware supports (I think)
		if(buffer[0] == RIFT_IRQ_SENSORS){
			handle_tracker_sensor_msg(priv, buffer, size);
		}else{
			LOGE("unknown message type: %u", buffer[0]);
		}
	}
}

static void calc_derived_values(rift_priv *priv)
{
	priv->calc_values.idp = 0.061f; // TODO settable.
	priv->calc_values.znear = 0.1f; // TODO settable.
	priv->calc_values.zfar = 1000.0f; // TODO settable.

	priv->calc_values.stereo_fov = DEG_TO_RAD(125.5144f); // TODO calculate.


	// Calculate the screen ratio of each subscreen.
	float full_ratio = (float)priv->display_info.h_resolution /
	                   (float)priv->display_info.v_resolution;
	float ratio = full_ratio / 2.0f;

	priv->calc_values.stereo_ratio = ratio;


	// Calculate where the lens is on each screen,
	// and with the given value offset the projection matrix.
	float screen_center = priv->display_info.h_screen_size / 4.0f;
	float lens_shift = screen_center - priv->display_info.lens_separation / 2.0f;
	float proj_offset = 4.0f * lens_shift / priv->display_info.h_screen_size;

	priv->calc_values.proj_offset = proj_offset;


	// Setup the base projection matrix. Each eye mostly have the
	// same projection matrix with the exception of the offset.
	omat4x4f_init_perspective(&priv->calc_values.proj_base,
	                          priv->calc_values.stereo_fov,
	                          priv->calc_values.stereo_ratio,
	                          priv->calc_values.znear,
	                          priv->calc_values.zfar);


	// Setup the two adjusted projection matricies. Each is setup to deal
	// with the fact that the lens is not in the center of the screen.
	// These matrices only change of the hardware changes, so static.
	mat4x4f translate;

	omat4x4f_init_translate(&translate, proj_offset, 0, 0);
	omat4x4f_mult(&translate,
	              &priv->calc_values.proj_base,
	              &priv->calc_values.proj_left);

	omat4x4f_init_translate(&translate, -proj_offset, 0, 0);
	omat4x4f_mult(&translate,
	              &priv->calc_values.proj_base,
	              &priv->calc_values.proj_right);
}
	
static int getf(ohmd_device* device, ohmd_float_value type, float* out)
{
	rift_priv* priv = rift_priv_get(device);

	switch(type){
	case OHMD_ROTATION_QUAT: {
			*(quatf*)out = priv->sensor_fusion.orient;
			break;
		}
	case OHMD_MAT4X4_LEFT_EYE_GL_MODELVIEW: {
			vec3f point = {{0, 0, 0}};
			mat4x4f orient, world_shift, result;
			omat4x4f_init_look_at(&orient, &priv->sensor_fusion.orient, &point);
			omat4x4f_init_translate(&world_shift, +(priv->calc_values.idp / 2.0f), 0, 0);
			omat4x4f_mult(&world_shift, &orient, &result);
			omat4x4f_transpose(&result, (mat4x4f*)out);
			break;
		}
	case OHMD_MAT4X4_RIGHT_EYE_GL_MODELVIEW: {
			vec3f point = {{0, 0, 0}};
			mat4x4f orient, world_shift, result;
			omat4x4f_init_look_at(&orient, &priv->sensor_fusion.orient, &point);
			omat4x4f_init_translate(&world_shift, -(priv->calc_values.idp / 2.0f), 0, 0);
			omat4x4f_mult(&world_shift, &orient, &result);
			omat4x4f_transpose(&result, (mat4x4f*)out);
			break;
		}
	case OHMD_MAT4X4_LEFT_EYE_GL_PROJECTION: {
			omat4x4f_transpose(&priv->calc_values.proj_left, (mat4x4f*)out);
			break;
		}
	case OHMD_MAT4X4_RIGHT_EYE_GL_PROJECTION: {
			omat4x4f_transpose(&priv->calc_values.proj_right, (mat4x4f*)out);
			break;
		}
	default:
		ohmd_set_error(priv->base.ctx, "invalid type given to getf (%d)", type);
		return -1;
		break;
	}

	return 0;
}

static void close_device(ohmd_device* device)
{
	LOGD("closing device");
	rift_priv* priv = rift_priv_get(device);
	hid_close(priv->handle);
	free(priv);
}

static ohmd_device* open_device(ohmd_driver* driver, ohmd_device_desc* desc)
{
	rift_priv* priv = ohmd_alloc(driver->ctx, sizeof(rift_priv));
	if(!priv)
		goto cleanup;

	priv->base.ctx = driver->ctx;

	// Open the HID device
	priv->handle = hid_open_path(desc->path);

	if(!priv->handle)
		goto cleanup;
	
	if(hid_set_nonblocking(priv->handle, 1) == -1){
		ohmd_set_error(driver->ctx, "failed to set non-blocking on device");
		goto cleanup;
	}

	unsigned char buf[FEATURE_BUFFER_SIZE];
	
	int size;

	// Read and decode the sensor range
	size = get_feature_report(priv, RIFT_CMD_RANGE, buf);
	decode_sensor_range(&priv->sensor_range, buf, size);
	dump_packet_sensor_range(&priv->sensor_range);

	// Read and decode display information
	size = get_feature_report(priv, RIFT_CMD_DISPLAY_INFO, buf);
	decode_sensor_display_info(&priv->display_info, buf, size);
	dump_packet_sensor_display_info(&priv->display_info);

	// Read and decode the sensor config
	size = get_feature_report(priv, RIFT_CMD_SENSOR_CONFIG, buf);
	decode_sensor_config(&priv->sensor_config, buf, size);
	dump_packet_sensor_config(&priv->sensor_config);

	// if the sensor has display info data, use HMD coordinate frame
	priv->coordinate_frame = priv->display_info.distortion_type != RIFT_DT_NONE ? RIFT_CF_HMD : RIFT_CF_SENSOR;

	// apply sensor config
	set_coordinate_frame(priv, priv->coordinate_frame);

	// set keep alive interval to n seconds
	pkt_keep_alive keep_alive = { 0, KEEP_ALIVE_VALUE };
	size = encode_keep_alive(buf, &keep_alive);
	send_feature_report(priv, buf, size);

	// Update the time of the last keep alive we have sent.
	priv->last_keep_alive = ohmd_get_tick();

	// update sensor settings with new keep alive value
	// (which will have been ignored in favor of the default 1000 ms one)
	size = get_feature_report(priv, RIFT_CMD_SENSOR_CONFIG, buf);
	decode_sensor_config(&priv->sensor_config, buf, size);
	dump_packet_sensor_config(&priv->sensor_config);


	calc_derived_values(priv);

	priv->base.update = update_device;
	priv->base.close = close_device;
	priv->base.getf = getf;

	ofusion_init(&priv->sensor_fusion);

	return &priv->base;

cleanup:
	if(priv)
		free(priv);

	return NULL;
}

static void get_device_list(ohmd_driver* driver, ohmd_device_list* list)
{
	// enumerate HID devices and add any Rifts found to the device list
#define OCULUS_VR_INC_ID 0x2833
#define RIFT_DEVKIT_ID 0x0001

	struct hid_device_info* devs = hid_enumerate(OCULUS_VR_INC_ID, RIFT_DEVKIT_ID);
	struct hid_device_info* cur_dev = devs;

	if(devs == NULL)
		return;

	while (cur_dev) {
		ohmd_device_desc* desc = &list->devices[list->num_devices++];

		strcpy(desc->driver, "OpenHMD Rift Driver");
		strcpy(desc->vendor, "Oculus VR, Inc.");
		strcpy(desc->product, "Rift (Devkit)");

		strcpy(desc->path, cur_dev->path);

		desc->driver_ptr = driver;

		cur_dev = cur_dev->next;
	}
	hid_free_enumeration(devs);
}

static void destroy_driver(ohmd_driver* drv)
{
	LOGD("shutting down driver");
	hid_exit();
	free(drv);
}

ohmd_driver* ohmd_create_oculus_rift_drv(ohmd_context* ctx)
{
	ohmd_driver* drv = ohmd_alloc(ctx, sizeof(ohmd_driver));
	if(drv == NULL)
		return NULL;

	drv->get_device_list = get_device_list;
	drv->open_device = open_device;
	drv->ctx = ctx;
	drv->get_device_list = get_device_list;
	drv->open_device = open_device;
	drv->destroy = destroy_driver;

	return drv;
}