module dlib.assets;

import dlib.aliases;
import dlib.util;
import dlib.alloc;

import std.file;
import std.stdio;
import std.exception;

File Asset_File;

FileHeader Asset_Header;

AssetInfo[] Asset_Info;

u8[][] Asset_Data;

const u32 FILE_VERSION = 2;
const u32 MODEL_VERSION = 1;

enum AssetType : u32
{
	None,
	ModelM3D,
	Shader,
	Texture,
}

alias AT = AssetType;

struct FileHeader
{
	u32 magic;
	u32 file_version;
	u64 asset_count;
	u64 asset_info_offset;
}

struct ModelHeader
{
	u32 magic;
	u32 model_version;
	u64 vertex_count;
	u64 vertex_offset;
	u64 index_count;
	u64 index_offset;
	u64 material_count;
	u64 material_offset;
	u64 texture_count;
	u64 texture_offset;
}

struct Vertex
{
	Vec4 color;
	Vec4 tangent;
	Vec3 pos;
	Vec3 normal;
	Vec2 uv;
}

struct ModelData
{
	Vertex[] 			vertices;
	u32[]		 			indices;
	Material[] 		materials;
	TextureInfo[] textures;
}

struct Material
{
	Vec4 ambient;
	Vec4 albedo;
	Vec4 specular;
	u32 albedo_texture;
	u32 ambient_texture;
	u32 specular_texture;
	u32 alpha_texture;
	b32 albedo_has_texture;
	b32 ambient_has_texture;
	b32 specular_has_texture;
	b32 alpha_has_texture;
	f32 shininess = 0.0;
	f32 alpha = 0.0;
}

struct TextureInfo
{
	string name;
	u32 	 id;
}

struct TextureHeader
{
	u64 str_length;
	u64 str_offset;
	u32 texture_id;
}

struct ModelMeta
{
	u64 index_count;
}

struct TexData
{
	void* data;
	TexMeta meta;
}

struct TexMeta
{
	u32 w;
	u32 h;
	u32 ch;
}

struct AssetInfo
{
	u64 hash;
	u64 offset;
	u64 length;
	AssetType type;
}

enum MatProp
{
	None,
	Ambient,
	Albedo,
	Specular,
	SpecularExp,
	Dissolve,     // Transparency 1.0 -> opaque
	Transparency, // Transparency 0.0 -> opaque
	Transmission,
	OpticalDensity,
	Illumination,
	AmbientMap,
	AlbedoMap,
	SpecularMap,
	SpecularHighlightMap,
	AlphaMap,
	BumpMap,
	DisplacementMap,
	Stencil,
	Roughness,
	RoughnessMap,
	Metallic,
	MetallicMap,
	Sheen,
	SheenMap,
	ClearcoatThickness,
	ClearcoatRoughness,
	Emissive,
	EmissiveMap,
	Anisotropy,
	AnisotropyMap,
	NormalMap,
}

bool Asset_Pack_Opened = false;

MatProp
GetMapProp(u8[] str)
{
	string s = ConvToStr!(u8)(str);
	switch(s) with(MatProp)
	{
		case "Ka":     return Ambient;
		case "Kd":     return Albedo;
		case "Ks":     return Specular;
		case "Ns":     return SpecularExp;
		case "d":      return Dissolve;
		case "Tr":     return Transparency;
		case "Tf":     return Transmission;
		case "Ni":     return OpticalDensity;
		case "illum":  return Illumination;
		case "map_Ka": return AmbientMap;
		case "map_Kd": return AlbedoMap;
		case "map_Ks": return SpecularMap;
		case "map_Ns": return SpecularHighlightMap;
		case "map_d":  return AlphaMap;
		case "map_bump":
		case "bump":   return BumpMap;
		case "disp":   return DisplacementMap;
		case "decal":  return Stencil;
		case "Pr":     return Roughness;
		case "map_Pr": return RoughnessMap;
		case "Pm":     return Metallic;
		case "map_Pm": return MetallicMap;
		case "Pc":     return ClearcoatThickness;
		case "Pcr":    return ClearcoatRoughness;
		case "Ke":     return Emissive;
		case "map_Ke": return EmissiveMap;
		case "aniso":  return Anisotropy;
		case "anisor": return AnisotropyMap;
		case "norm":   return NormalMap;
		default:        return None;
	}
}

debug
{

bool g_DIR_SET = false;

void
SetDir()
{
	if(exists("assets"))
	{
		chdir("./assets");
	}
	else if(exists("Gears") || exists("Gears.exe"))
	{
		chdir("../assets");
	}
	else
	{
		assert(false, "Unable to set directory");
	}

	g_DIR_SET = true;
}

u8[]
LoadAssetData(Arena* arena, string name)
{
	if(!g_DIR_SET)
	{
		SetDir();
	}

	File f;
	try 
	{
		f = File(name, "rb");
	}
	catch (ErrnoException e)
	{
		assert(false, "Unable to open file");
	}

	u8[] mem = Alloc!(u8)(arena, f.size());
	return f.rawRead(mem);
}

}
else
{

void
OpenAssetPack()
{
	if(!Asset_Pack_Opened)
	{
		bool success = true;
		string file_path = exists("build/assets.sgp") ? "build/assets.sgp" : "assets.sgp";

		// TODO: replace this with something that doesn't throw an exception and figure out if this is the best way to handle thing (probably isnt)
		try 
		{
			Asset_File = File(file_path, "rb");
		}
		catch (ErrnoException e)
		{
			Logf("OpenAssetPack failure: Unable to open file %s", file_path);
			assert(false, "Unable to open asset pack file");
		}

		FileHeader[1] header_arr;

		Asset_File.rawRead(header_arr);

		Asset_Header = header_arr[0];

		Asset_Info = Alloc!(AssetInfo)(Asset_Header.asset_count);
		Asset_Data = Alloc!(u8[])(Asset_Header.asset_count);

		assert(Asset_Header.file_version == FILE_VERSION, "OpenAssetPack failure: file version incorrect");

		Asset_File.seek(Asset_Header.asset_info_offset);

		Asset_File.rawRead(Asset_Info);
	}
}

pragma(inline) void
CheckAssetPack()
{
	if(!Asset_Pack_Opened)
	{
		OpenAssetPack();
	}
}

AssetInfo
GetAssetInfo(string name)
{
	CheckAssetPack();

	u64 hash = Hash(name);

	AssetInfo asset_info;
	foreach(i, info; Asset_Info)
	{
		if(info.hash == hash)
		{
			asset_info = info;
			break;
		}
	}

	assert(asset_info.hash != 0, "GetAssetInfo failure: unable to find matching asset");

	return asset_info;
}

u8[]
LoadAssetData(Arena* arena, string name)
{
	CheckAssetPack();

	u64 hash = Hash(name);
	u8[] data = null;

	foreach(i, info; Asset_Info)
	{
		if(info.hash == hash)
		{
			data = Alloc!(u8)(arena, info.length);
			Asset_File.seek(info.offset);
			Asset_File.rawRead(data);
			assert(data != null && data.length == info.length, "LoadAssetData failure: Asset data loaded incorrectly");

			break;
		}
	}

	return data;
}

u8[]
LoadAssetData(string name)
{
	CheckAssetPack();

	u64 hash = Hash(name);
	u8[] data = null;

	foreach(i, info; Asset_Info)
	{
		if(info.hash == hash)
		{
			if(Asset_Data[i].ptr == null)
			{
				Asset_Data[i] = Alloc!(u8)(info.length);
				Asset_File.seek(info.offset);
				Asset_File.rawRead(Asset_Data[i]);
				assert(Asset_Data[i] != null && Asset_Data[i].length == info.length, "LoadAssetData failure: Asset data loaded incorrectly.");
			}

			data = Asset_Data[i];
			break;
		}
	}

	return data;
}

void
UnloadAssetData(string name)
{
	u64 hash = Hash(name);

	foreach(i, info; Asset_Info)
	{
		if(info.hash == hash)
		{
			if(Asset_Data[i] != null)
			{
				Free(Asset_Data[i]);
				break;
			}
		}
	}
}

}

unittest
{
	{
		MatProp prop = GetMapProp(cast(u8[])r"Ka");
	}
}