// SPDX-License-Identifier: GPL-2.0-or-later
/* SPDX-FileCopyrightText: 2004-2015  Simon Wunderlich <sw@simonwunderlich.de>
 */

#include "global.h"
#include <string.h>		/*  memcpy() */
#if G_SDL
#include <SDL_opengl.h>		/*  GL_RESCALE_NORMAL */
#include <SDL.h>		/*  SDL_GL_SwapBuffers */
#else
#include <GL/gl.h>		/*  GLint */
#include <GL/glext.h>		/*  GL_RESCALE_NORMAL */
#endif
#include <math.h>		/*  sin(),cos() */
#ifndef INFINITY
#define INFINITY 1<<30
#endif
/*  this file handles graphics routines */
/*  local prototypes ... */
static void render_virtual_object(struct t_obj *o);
/*  ... and types/variables */
static int select_mode = 0;
int winw, winh;

/*  this detects and opens the SDL things */

int graphics_init(void)
{
	GLfloat shin[] = { 16.0 };
	switch (frame_mode) {
#ifdef G_SDL
	case FRAME_SDL:
		graphics_init_sdl();
		break;
#endif
	default:
		return -1;
	}
	/* light */
	glEnable(GL_LIGHTING);
	glEnable(GL_LIGHT0);

	/* depth test */
	glEnable(GL_DEPTH_TEST);

	/* textures */
	glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
	glEnable(GL_TEXTURE_2D);
	glShadeModel(GL_SMOOTH);
	glDisable(GL_DITHER);

	/* lines */
	glHint(GL_LINE_SMOOTH_HINT, GL_FASTEST);
	glLineWidth(1.0);
	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);

	/* polygon smoothing */
	glDisable(GL_POLYGON_SMOOTH);

	/* normalizing */
	glDisable(GL_AUTO_NORMAL);
	glDisable(GL_NORMALIZE);	/* don't use the expensive GL_NORMALIZE, we use uniform scaling so GL_RESCALE_NORMAL is sufficent */
	glEnable(GL_RESCALE_NORMAL);

	/* blending */
	glEnable(GL_BLEND);
	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

	/* set shininess */
	glMaterialfv(GL_FRONT, GL_SHININESS, shin);
	graphics_reshape(X_RES, Y_RES);

	/* face culling */
	glCullFace(GL_FRONT);
	glEnable(GL_CULL_FACE);
	return 0;
}

/*  this is to be called when the window is resized or created ... */
void graphics_reshape(int w, int h)
{
	glViewport(0, 0, (GLsizei) w, (GLsizei) h);
	winw = w;
	winh = h;
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	if (w > h)
		glFrustum(-((1.0 * w) / h), (1.0 * w) / h, -1.0, 1.0, 1.0, 5000);
	else
		glFrustum(-1.0, 1.0, -(1.0 * h) / w, (1.0 * h) / w, 1.0, 5000);
	glMatrixMode(GL_MODELVIEW);
	if (procs_p != NULL)
		event_cam_changed();
}

static void render_virtual_object(struct t_obj *o)
{
	struct t_process *ap;
	struct t_vertex x, y;
	int32_t j, k;
	t_mtrx m;

	glPushMatrix();
	glMultMatrixf(o->m);
	glGetFloatv(GL_MODELVIEW_MATRIX, m);
	cull_get_planes();
	if (NULL == (ap = get_proc_by_pid(o->virtual_pid))) {	/*  the clean way */
		errds(HIGH, "render_by_mcp()", "not existing pid (%p) referenced by mcp-object!!", (void *)o);
	} else {
		/*  now go throu the objects of our app  */
		for (j = 0; j < ap->n_obj; j++) {
			if (ap->object[j] != NULL) {
				if (((select_mode == 0) && ap->object[j]->oflags & OF_VISIBLE) || ((select_mode == 1) && (ap->object[j]->oflags & OF_SELECTABLE))) {	/* either select mode is off or it's selectable */
					x.x = x.y = x.z = 0.0f;
					mySetMatrix(ap->object[j]->m);	/* get into position ... */
					myTransformV(&x);
					y.x = 1.0;
					y.y = y.z = 0.0f;
					myTransformV(&y);
					y.x -= x.x;
					y.y -= x.y;
					y.z -= x.z;

					k = cull_sphere_in_frustum(&x, ap->object[j]->r * sqrt(y.x * y.x + y.y * y.y + y.z * y.z));
					if (k) {
						if (select_mode == 1)
							glPushName(j);
						obj_render(ap, j);
						if (select_mode == 1)
							glPopName();
					}
				}
			}
		}
	}
	glPopMatrix();
}

/*  this functions renders by going from mcp objects [as it should be],  */
/*  recursively positiniong the objects into the space. */
int render_by_mcp(void)
{
	struct t_process *p = get_proc_by_pid(MCP);
	int32_t i;
	struct t_obj *o;
	struct t_vertex x, y;
	int k;
	for (i = 0; i < p->n_obj; i++) {	/* check all mcp objects ... */
		o = p->object[i];
		if (o != NULL) {
			if ((select_mode == 0 && o->oflags & OF_VISIBLE) || (select_mode == 1 && o->oflags & OF_SELECTABLE)) {	/*  it's even visible ;) */
				if (o->oflags & OF_VIRTUAL) {	/*  we have an app here. */
					if (o->r != 0.0) {
						cull_get_planes();
						mySetMatrix(o->m);
						x.x = x.y = x.z = 0.0f;
						myTransformV(&x);
						y.x = 1.0;
						y.y = y.z = 0.0f;
						myTransformV(&y);
						y.x -= x.x;
						y.y -= x.y;
						y.z -= x.z;

						k = cull_sphere_in_frustum(&x, o->r * sqrt(y.x * y.x + y.y * y.y + y.z * y.z));
						s3dprintf(VLOW, "mcp-object %d is in %s frustum", i, k ? "" : "not");
						if (k) {
							if (select_mode == 1) {
								s3dprintf(VLOW, "object %d in culling frustrum!", i);
								glLoadName(i);
							}
							render_virtual_object(o);
						} else {
							if (select_mode == 1) {
								s3dprintf(VLOW, "object %d not in culling frustrum!", i);
							}
						}
					}
				} else if ((o->oflags & OF_CLONE) && (p->object[o->clone_ooid]->oflags & OF_VIRTUAL)) {	/* it's a clone of an app */
					if (select_mode == 1)
						glLoadName(o->clone_ooid);	/*TODO: what to do if a clone is selected?! */
					glPushMatrix();
					render_virtual_object(o);
					render_virtual_object(p->object[o->clone_ooid]);
					glPopMatrix();
				} else {	/* it's a "regular" mcp object */
					if (select_mode == 1) {
						s3dprintf(VLOW, "mcp object no. %d", i);
						glLoadName(-1);
						glPushName(i);
					}
					obj_render(p, i);
					if (select_mode == 1)
						glPopName();
				}
			}
		}
	}
	return 0;
}

/* this picks objects from their screen-positions and sends
 * OBK_CLICK-events for the selected object(s).
 * TODO: how big should the select buffer be? */
#define SBSIZE 65536
int graphics_pick_obj(int x, int y)
{
	int i, j;
	GLint viewport[4];
	GLfloat xpos, ypos;
	float big, z1, z2;
	int32_t mcp_o, o;
	struct t_process *p = get_proc_by_pid(MCP);
	GLuint select_buf[SBSIZE], *ptr;
	int hits, names;
	t_mtrx m;

	select_mode = 1;
	glSelectBuffer(SBSIZE, select_buf);
	glRenderMode(GL_SELECT);
	glMatrixMode(GL_PROJECTION);
	/*  count the objects .... */
	glPushMatrix();
	glLoadIdentity();
	glGetIntegerv(GL_VIEWPORT, viewport);
	if (winw > winh) {
		xpos = ((x - winw / 2.0) / (winw / 2.0)) * (((double)winw / winh));
		ypos = (((winh - y) - winh / 2.0) / (winh / 2.0));
	} else {
		xpos = ((x - winw / 2.0) / (winw / 2.0));
		ypos = (((winh - y) - winh / 2.0) / (winh / 2.0)) * (((double)winh / winw));
	}
#define mnear 0.001		/*  omg this is so dirty ... but works after all */
	glFrustum(xpos - mnear, xpos + mnear, ypos - mnear, ypos + mnear, 1, 5000);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();	/*  get into position ... */
	mySetMatrix(p->object[0]->m);
	myInvert();
	myGetMatrix(m);
	glMultMatrixf(m);

	glInitNames();
	glPushName(0);
	render_by_mcp();
	glFlush();
	hits = glRenderMode(GL_RENDER);
	if (hits > 0) {
		big = INFINITY;
		s3dprintf(LOW, "had %d hits", hits);
		ptr = select_buf;
		mcp_o = o = names = -1;
		/* check all the hits, only select the nearest ... */
		for (i = 0; i < hits; i++) {
			names = *ptr;
			ptr++;
			z1 = (float)*ptr / 0x7fffffff;
			ptr++;
			z2 = (float)*ptr / 0x7fffffff;
			ptr++;
			if (z1 < big) {
				mcp_o = o = -1;
				for (j = 0; j < names; j++) {
					switch (j) {
					case 0:
						mcp_o = *ptr;
						break;
					case 1:
						o = *ptr;
						break;
					}
					ptr++;
				}
				big = z1;
			} else
				for (j = 0; j < names; j++)
					ptr++;
			s3dprintf(VLOW, "[HIT %d] names %d [z1:%f|z2:%f] mcp_o=%d, o=%d ", i, names, z1, z2, mcp_o, o);
		}
		s3dprintf(VLOW, "mcp_o= %d, o= %d", mcp_o, o);
		if (mcp_o == -1) {	/* it's an mcp object */
			s3dprintf(LOW, "clicked on mcp-object no. %d", o);
			event_obj_click(p, o);
		} else if ((names > 1) && ((mcp_o >= 0) && (mcp_o < p->n_obj))) {	/* it's an usual object */
			s3dprintf(LOW, "clicked on mcp-object %d, object %d", mcp_o, o);
			if (p->object[mcp_o] != NULL) {	/*  that shouldn't happen anyways ... */
				obj_debug(get_proc_by_pid(p->object[mcp_o]->virtual_pid), o);
				event_obj_click(get_proc_by_pid(p->object[mcp_o]->virtual_pid), o);
			}
		}
	}
	glMatrixMode(GL_PROJECTION);
	glPopMatrix();
	glMatrixMode(GL_MODELVIEW);
	select_mode = 0;
	return 0;
}

void graphics_main(void)
{
	struct t_process *p = get_proc_by_pid(MCP);
	t_mtrx m;
	GLfloat pos[] = { 0, 50, 50, 1.0 };
	GLfloat light0_spec[] = { 0.7, 0.7, 0.7, 0.0 };
	GLfloat light0_shininess[] = { 1.0 };
	GLfloat light0_diff[] = { 0.5, 0.5, 0.5, 1.0 };
	GLfloat light0_amb[] = { 1.0, 1.0, 1.0, 1.0 };

	select_mode = 0;
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);	/*  clear screen */
	/*  set up the cam ... */
	glMatrixMode(GL_MODELVIEW);

	glLightfv(GL_LIGHT0, GL_AMBIENT, light0_amb);
	glLightfv(GL_LIGHT0, GL_DIFFUSE, light0_diff);
	glLightfv(GL_LIGHT0, GL_SPECULAR, light0_spec);
	glLightfv(GL_LIGHT0, GL_SHININESS, light0_shininess);

	glLoadIdentity();

	mySetMatrix(p->object[0]->m);
	myInvert();
	myGetMatrix(m);
	glMultMatrixf(m);
	glLightfv(GL_LIGHT0, GL_POSITION, pos);

	glPushMatrix();		/*  save the cam */
	render_by_mcp();
	glPopMatrix();		/*  restore the cam */
	glLoadIdentity();
	glMultMatrixf(m);

	switch (frame_mode) {
#ifdef G_SDL
	case FRAME_SDL:
		/* SDL will glFlush itself */
#if SDL_VERSION_ATLEAST(2,0,0)
		SDL_GL_SwapWindow(sdl_window);
#else
		SDL_GL_SwapBuffers();
#endif
		break;
#endif
#ifdef G_GLX
	case FRAME_GLX:
		...
#endif
	}
}

/*  quit the graphic-interface */
int graphics_quit(void)
{
	return 0;
}