/*
===========================================================================
Copyright (C) 2023 the OpenMoHAA team

This file is part of OpenMoHAA source code.

OpenMoHAA source code 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.

OpenMoHAA source code 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 OpenMoHAA source code; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
===========================================================================
*/

#include "cm_local.h"

static char com_token[MAX_TOKEN_CHARS];

/*
================
CM_NextCsvToken
================
*/
char* CM_NextCsvToken(char** text, qboolean crossline) {
    char* p;
    char* out;
    char c;
    int i;
    qboolean newline;
    qboolean comma;

    com_token[0] = 0;
    p = *text;
    if (!p) {
        return com_token;
    }

    for (c = *p; isspace(c); p++, c = *p)
    {
        if (c == '\n' && !crossline) {
            break;
        }
    }

    out = com_token;

    for (i = 0; ; i++, p++) {
        c = *p;

        newline = qfalse;
        comma = qfalse;

        if (*p && c != ',') {
            comma = qtrue;
        }

        if (comma && c != '\n') {
            newline = qtrue;
        }

        if (!newline) {
            break;
        }

        *out = c;
        out++;
    }

    if (c == ',') {
        p++;
    }

    while (i > 0) {
        if (!isspace(com_token[i - 1])) {
            break;
        }

        i--;
    }

    com_token[i] = 0;
    *text = p;

    if (!p[0]) {
        *text = NULL;
    }

    return com_token;
}

/*
================
CM_SetupObfuscationMapping
================
*/
obfuscation_t* CM_SetupObfuscationMapping() {
	obfuscation_t* list;
    obfuscation_t* obfuscation;
    char** files;
    int numFiles;
    int numObfuscations;
	int i, j;
	
	list = (obfuscation_t*)Hunk_AllocateTempMemory(sizeof(obfuscation_t) * MAX_OBFUSCATIONS);
	for (i = 0; i < MAX_OBFUSCATIONS; i++) {
		list[i].name[0] = 0;
		list[i].heightDensity = 0;
		list[i].widthDensity = 0;
	}

    files = FS_ListFiles("scripts/", ".csv", qfalse, &numFiles);
    numObfuscations = 0;

    for (i = 0; i < numFiles; ++i) {
        const char* filename = va("scripts/%s", files[i]);
        void* buffer;
        char* text;
        char* token;

        if (FS_ReadFile(filename, &buffer) < 0) {
            continue;
        }

        text = (char*)buffer;
        while (text) {
            token = CM_NextCsvToken(&text, qtrue);
            if (!token[0]) {
                break;
            }

            for (j = 0; j < numObfuscations; ++j)
            {
                if (!Q_stricmp(token, list[j].name))
                {
                    Com_Printf("WARNING: using redefinition of obfuscation for '%s' in '%s'\n", token, files[i]);
                    break;
                }
            }

            obfuscation = &list[j];
            Q_strncpyz(obfuscation->name, token, sizeof(obfuscation->name));

            token = CM_NextCsvToken(&text, qfalse);
            if (!text) {
                Com_Printf(
                    "WARNING: unexpected EOF in definition of obfuscation for '%s' in '%s'; skipping\n",
                    obfuscation->name,
                    files[i]
                );
                break;
            }

            if (token[0]) {
                float maxNumVolumes = atof(token);

                if (maxNumVolumes > 0) {
                    obfuscation->widthDensity = 0.5f / maxNumVolumes;
                } else {
                    obfuscation->widthDensity = 0;
                }

                token = CM_NextCsvToken(&text, 0);
                if (!text) {
                    Com_Printf(
                        "WARNING: unexpected EOF in definition of obfuscation for '%s' in '%s'; skipping\n",
                        obfuscation->name,
                        files[i]
                    );
                    break;
                }

                if (token[0]) {
                    float maxDist = atof(token);

                    if (maxDist > 0) {
                        obfuscation->heightDensity = 1.f / maxDist;
                    } else {
                        obfuscation->heightDensity = 0;
                    }

                    if (numObfuscations == MAX_OBFUSCATIONS) {
                        Com_Printf("WARNING: exceeded MAX_OBFUSCATIONS (%i)", numObfuscations);
                    } else {
                        numObfuscations++;
                    }
                } else {
                    Com_Printf(
                        "WARNING: missing max distance thorugh obscuring volumes for '%s' in '%s'; skipping\n",
                        obfuscation->name,
                        files[i]
                    );
                    SkipRestOfLine(&text);
                }
            } else {
                Com_Printf(
                    "WARNING: missing max number of obscuring volumes for '%s' in '%s'; skipping\n",
                    obfuscation->name,
                    files[i]
                );
                SkipRestOfLine(&text);
            }
        }

        FS_FreeFile(buffer);
    }

    list[numObfuscations].name[0] = 0;

	return list;
}

/*
================
CM_ReleaseObfuscationMapping
================
*/
void CM_ReleaseObfuscationMapping(obfuscation_t* obfuscation) {
	Hunk_FreeTempMemory(obfuscation);
}

/*
================
CM_ObfuscationForShader
================
*/
void CM_ObfuscationForShader(obfuscation_t* list, const char* shaderName, float* widthDensity, float* heightDensity) {
	obfuscation_t* current;

	for (current = list; current->name[0]; current++) {
		if (!Q_stricmp(shaderName, current->name)) {
			*widthDensity = current->widthDensity;
			*heightDensity = current->heightDensity;
		}
	}

	Com_Printf("WARNING: using default obfuscation for shader %s\n", shaderName);
	*widthDensity = 1.f / 16.f;
	*heightDensity = 1.f / 1024.f;
}

/*
================
CM_ObfuscationTraceThroughBrush
================
*/
float CM_ObfuscationTraceThroughBrush( traceWork_t *tw, cbrush_t *brush ) {
    int i;
    cplane_t* plane;
    float dist;
    float enterFrac, leaveFrac;
    float enterDensity, leaveDensity;
    float delta;
    float d1, d2;
    float f;
    cbrushside_t* side;

	enterFrac = 0;
    enterDensity = 0;
	leaveFrac = 1.0;
    leaveDensity = 0;

	//
	// compare the trace against all planes of the brush
	// find the latest time the trace crosses a plane towards the interior
	// and the earliest time the trace crosses a plane towards the exterior
	//
	for( i = 0; i < brush->numsides; i++ ) {
		side = brush->sides + i;
		plane = side->plane;

		// adjust the plane distance apropriately for mins/maxs
		//dist = plane->dist - DotProduct( tw->offsets[ plane->signbits ], plane->normal );
        dist = plane->dist;

		d1 = DotProduct( tw->start, plane->normal ) - dist;
		d2 = DotProduct( tw->end, plane->normal ) - dist;

		// if it doesn't cross the plane, the plane isn't relevent
		if( d1 >= 0 && d2 >= 0 ) {
            return 0;
		}

        if (d1 < 0 && d2 > 0) {
            f = d1 / (d1 - d2);
            if (leaveFrac > f) {
                leaveFrac = f;
            }
            leaveDensity = cm.shaders[brush->shaderNum].obfuscationWidthDensity;
        } else if (d1 > 0 && d2 < 0) {
            f = d1 / (d1 - d2);
            if (enterFrac < f) {
                enterFrac = f;
            }
            enterDensity = cm.shaders[brush->shaderNum].obfuscationWidthDensity;
        }
	}

    delta = leaveFrac - enterFrac;
    if (delta <= 0) {
        return 0;
    }

    return enterDensity + cm.shaders[brush->shaderNum].obfuscationHeightDensity * tw->radius * delta + leaveDensity;
}

/*
================
CM_ObfuscationTraceToLeaf
================
*/
float CM_ObfuscationTraceToLeaf( traceWork_t *tw, cLeaf_t *leaf ) {
	int k;
	cbrush_t *b;
	float total;

	total = 0;
	// test box position against all brushes in the leaf
	for( k = 0; k<leaf->numLeafBrushes; k++ ) {
		b = &cm.brushes[ cm.leafbrushes[ leaf->firstLeafBrush + k ] ];
		if( b->checkcount == cm.checkcount ) {
			continue;	// already checked this brush in another leaf
		}
		b->checkcount = cm.checkcount;

		if( !( b->contents & CONTENTS_DONOTENTER ) ) {
			continue;
		}

		total += CM_ObfuscationTraceThroughBrush( tw, b );
	}

	return total;
}

/*
==================
CM_ObfuscationTraceThroughTree

Traverse all the contacted leafs from the start to the end position.
If the trace is a point, they will be exactly in order, but for larger
trace volumes it is possible to hit something in a later leaf with
a smaller intercept fraction.
==================
*/
float CM_ObfuscationTraceThroughTree( traceWork_t *tw, int num, float p1f, float p2f, vec3_t p1, vec3_t p2) {
	cNode_t		*node;
	cplane_t	*plane;
	float		t1, t2;
	float		frac, frac2;
	float		idist;
	vec3_t		mid;
	int			side;
	float		midf;

	// if < 0, we are in a leaf node
	if (num < 0) {
		return CM_ObfuscationTraceToLeaf( tw, &cm.leafs[-1-num] );
	}

	//
	// find the point distances to the seperating plane
	// and the offset for the size of the box
	//
	node = cm.nodes + num;
	plane = node->plane;

	// adjust the plane distance apropriately for mins/maxs
	if ( plane->type < 3 ) {
		t1 = p1[plane->type] - plane->dist;
		t2 = p2[plane->type] - plane->dist;
	} else {
		t1 = DotProduct (plane->normal, p1) - plane->dist;
		t2 = DotProduct (plane->normal, p2) - plane->dist;
	}

	// see which sides we need to consider
	if ( t1 >= SURFACE_CLIP_EPSILON && t2 >= SURFACE_CLIP_EPSILON) {
		return CM_ObfuscationTraceThroughTree( tw, node->children[0], p1f, p2f, p1, p2 );
	}
	if ( t1 < -SURFACE_CLIP_EPSILON && t2 < -SURFACE_CLIP_EPSILON) {
		return CM_ObfuscationTraceThroughTree( tw, node->children[1], p1f, p2f, p1, p2 );
	}

	// put the crosspoint SURFACE_CLIP_EPSILON pixels on the near side
	if ( t1 < t2 ) {
		idist = 1.0/(t1-t2);
		side = 1;
		frac2 = (t1 + SURFACE_CLIP_EPSILON)*idist;
		frac = (t1 + SURFACE_CLIP_EPSILON)*idist;
	} else if (t1 > t2) {
		idist = 1.0/(t1-t2);
		side = 0;
		frac2 = (t1 - SURFACE_CLIP_EPSILON)*idist;
		frac = (t1 + SURFACE_CLIP_EPSILON)*idist;
	} else {
		side = 0;
		frac = 1;
		frac2 = 0;
	}

	// move up to the node
	if ( frac < 0 ) {
		frac = 0;
	} else if ( frac > 1 ) {
		frac = 1;
	}

	midf = p1f + (p2f - p1f)*frac;

	mid[0] = p1[0] + frac*(p2[0] - p1[0]);
	mid[1] = p1[1] + frac*(p2[1] - p1[1]);
	mid[2] = p1[2] + frac*(p2[2] - p1[2]);

	CM_ObfuscationTraceThroughTree( tw, node->children[side], p1f, midf, p1, mid );


	// go past the node
	if ( frac2 < 0 ) {
		frac2 = 0;
	} else if ( frac2 > 1 ) {
		frac2 = 1;
	}

	midf = p1f + (p2f - p1f)*frac2;

	mid[0] = p1[0] + frac2*(p2[0] - p1[0]);
	mid[1] = p1[1] + frac2*(p2[1] - p1[1]);
	mid[2] = p1[2] + frac2*(p2[2] - p1[2]);

	return CM_ObfuscationTraceThroughTree( tw, node->children[side^1], midf, p2f, mid, p2 );
}

/*
================
CM_ObfuscationTrace
================
*/
float CM_ObfuscationTrace(const vec3_t start, const vec3_t end, clipHandle_t handle) {
    cmodel_t* model;
    vec3_t delta;
    traceWork_t tw;

    model = CM_ClipHandleToModel(handle);

    c_traces++;
    cm.checkcount++;

    VectorCopy(start, tw.start);
    VectorCopy(end, tw.end);
    VectorSubtract(tw.end, tw.start, delta);
    tw.radius = VectorLength(delta);

    if (handle) {
        return CM_ObfuscationTraceToLeaf(&tw, &model->leaf);
    } else {
        return CM_ObfuscationTraceThroughTree(&tw, 0, 0.0, 1.0, tw.start, tw.end);
    }
}

/*
================
CM_VisualObfuscation
================
*/
float CM_VisualObfuscation(const vec3_t start, const vec3_t end) {
    return CM_ObfuscationTrace(start, end, 0);
}