//
// Copyright (c) 2009 Mikko Mononen memon@inside.org
//
// This software is provided 'as-is', without any express or implied
// warranty.  In no event will the authors be held liable for any damages
// arising from the use of this software.
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
// 1. The origin of this software must not be misrepresented; you must not
//    claim that you wrote the original software. If you use this software
//    in a product, an acknowledgment in the product documentation would be
//    appreciated but is not required.
// 2. Altered source versions must be plainly marked as such, and must not be
//    misrepresented as being the original software.
// 3. This notice may not be removed or altered from any source distribution.
//

#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "DetourTileNavMesh.h"
#include "DetourCommon.h"

bool dtCreateNavMeshTileData(const unsigned short* verts, const int nverts,
							 const unsigned short* polys, const int npolys, const int nvp,
							 const unsigned short* dmeshes, const float* dverts, const int ndverts,
							 const unsigned char* dtris, const int ndtris, 
							 const float* bmin, const float* bmax, float cs, float ch, int tileSize, int walkableClimb,
							 unsigned char** outData, int* outDataSize)
{
	if (nvp != DT_TILE_VERTS_PER_POLYGON)
		return false;
	if (nverts >= 0xffff)
		return false;
	
	if (!nverts)
		return false;
	if (!npolys)
		return false;
	if (!dmeshes || !dverts || ! dtris)
		return false;
	
	// Find portal edges which are at tile borders.
	int nedges = 0;
	int nportals = 0;
	for (int i = 0; i < npolys; ++i)
	{
		const unsigned short* p = &polys[i*2*nvp];
		for (int j = 0; j < nvp; ++j)
		{
			if (p[j] == 0xffff) break;
			int nj = j+1;
			if (nj >= nvp || p[nj] == 0xffff) nj = 0;
			const unsigned short* va = &verts[p[j]*3];
			const unsigned short* vb = &verts[p[nj]*3];
			
			nedges++;
			
			if (va[0] == tileSize && vb[0] == tileSize)
				nportals++; // x+
			else if (va[2] == tileSize && vb[2]  == tileSize)
				nportals++; // z+
			else if (va[0] == 0 && vb[0] == 0)
				nportals++; // x-
			else if (va[2] == 0 && vb[2] == 0)
				nportals++; // z-
		}
	}

	const int maxLinks = nedges + nportals*2;
	
	
	// Find unique detail vertices.
	int uniqueDetailVerts = 0;
	if (dmeshes)
	{
		for (int i = 0; i < npolys; ++i)
		{
			const unsigned short* p = &polys[i*nvp*2];
			int ndv = dmeshes[i*4+1];
			int nv = 0;
			for (int j = 0; j < nvp; ++j)
			{
				if (p[j] == 0xffff) break;
				nv++;
			}
			ndv -= nv;
			uniqueDetailVerts += ndv;
		}
	}
	
	// Calculate data size
	const int headerSize = sizeof(dtTileHeader);
	const int vertsSize = sizeof(float)*3*nverts;
	const int polysSize = sizeof(dtTilePoly)*npolys;
	const int linksSize = sizeof(dtTileLink)*maxLinks;
	const int detailMeshesSize = sizeof(dtTilePolyDetail)*npolys;
	const int detailVertsSize = sizeof(float)*3*uniqueDetailVerts;
	const int detailTrisSize = sizeof(unsigned char)*4*ndtris;
	
	const int dataSize = headerSize + vertsSize + polysSize + linksSize +
						 detailMeshesSize + detailVertsSize + detailTrisSize;
	unsigned char* data = new unsigned char[dataSize];
	if (!data)
		return false;
	memset(data, 0, dataSize);
	
	unsigned char* d = data;
	dtTileHeader* header = (dtTileHeader*)d; d += headerSize;
	float* navVerts = (float*)d; d += vertsSize;
	dtTilePoly* navPolys = (dtTilePoly*)d; d += polysSize;
	d += linksSize;
	dtTilePolyDetail* navDMeshes = (dtTilePolyDetail*)d; d += detailMeshesSize;
	float* navDVerts = (float*)d; d += detailVertsSize;
	unsigned char* navDTris = (unsigned char*)d; d += detailTrisSize;
	
	
	// Store header
	header->magic = DT_TILE_NAVMESH_MAGIC;
	header->version = DT_TILE_NAVMESH_VERSION;
	header->npolys = npolys;
	header->nverts = nverts;
	header->maxlinks = maxLinks;
	header->bmin[0] = bmin[0];
	header->bmin[1] = bmin[1];
	header->bmin[2] = bmin[2];
	header->bmax[0] = bmax[0];
	header->bmax[1] = bmax[1];
	header->bmax[2] = bmax[2];
	header->ndmeshes = npolys;
	header->ndverts = uniqueDetailVerts;
	header->ndtris = ndtris;
	
	// Store vertices
	for (int i = 0; i < nverts; ++i)
	{
		const unsigned short* iv = &verts[i*3];
		float* v = &navVerts[i*3];
		v[0] = bmin[0] + iv[0] * cs;
		v[1] = bmin[1] + iv[1] * ch;
		v[2] = bmin[2] + iv[2] * cs;
	}
	
	// Store polygons
	const unsigned short* src = polys;
	for (int i = 0; i < npolys; ++i)
	{
		dtTilePoly* p = &navPolys[i];
		p->nv = 0;
		for (int j = 0; j < nvp; ++j)
		{
			if (src[j] == 0xffff) break;
			p->v[j] = src[j];
			p->n[j] = (src[nvp+j]+1) & 0xffff;
			p->nv++;
		}
		src += nvp*2;
	}

	// Store portal edges.
	for (int i = 0; i < npolys; ++i)
	{
		dtTilePoly* poly = &navPolys[i];
		for (int j = 0; j < poly->nv; ++j)
		{
			int nj = j+1;
			if (nj >= poly->nv) nj = 0;

			const unsigned short* va = &verts[poly->v[j]*3];
			const unsigned short* vb = &verts[poly->v[nj]*3];
						
			if (va[0] == tileSize && vb[0] == tileSize) // x+
				poly->n[j] = 0x8000 | 0;
			else if (va[2] == tileSize && vb[2]  == tileSize) // z+
				poly->n[j] = 0x8000 | 1;
			else if (va[0] == 0 && vb[0] == 0) // x-
				poly->n[j] = 0x8000 | 2;
			else if (va[2] == 0 && vb[2] == 0) // z-
				poly->n[j] = 0x8000 | 3;
		}
	}

	// Store detail meshes and vertices.
	// The nav polygon vertices are stored as the first vertices on each mesh.
	// We compress the mesh data by skipping them and using the navmesh coordinates.
	unsigned short vbase = 0;
	for (int i = 0; i < npolys; ++i)
	{
		dtTilePolyDetail& dtl = navDMeshes[i];
		const int vb = dmeshes[i*4+0];
		const int ndv = dmeshes[i*4+1];
		const int nv = navPolys[i].nv;
		dtl.vbase = vbase;
		dtl.nverts = ndv-nv;
		dtl.tbase = dmeshes[i*4+2];
		dtl.ntris = dmeshes[i*4+3];
		// Copy vertices except the first 'nv' verts which are equal to nav poly verts.
		if (ndv-nv)
		{
			memcpy(&navDVerts[vbase*3], &dverts[(vb+nv)*3], sizeof(float)*3*(ndv-nv));
			vbase += ndv-nv;
		}
	}
	// Store triangles.
	memcpy(navDTris, dtris, sizeof(unsigned char)*4*ndtris);
	
	*outData = data;
	*outDataSize = dataSize;
	
	return true;
}