#include "gl33core_renderer.h"

#include <stdio.h>

#include "../../src/libsm64.h"
#include "../renderer.h"
#include "../context.h"
#include "../cglm.h"
#include "../level.h"

static const char *MARIO_SHADER =
"\n uniform mat4 view;"
"\n uniform mat4 projection;"
"\n uniform sampler2D marioTex;"
"\n "
"\n v2f vec3 v_color;"
"\n v2f vec3 v_normal;"
"\n v2f vec3 v_light;"
"\n v2f vec2 v_uv;"
"\n "
"\n #ifdef VERTEX"
"\n "
"\n     layout(location = 0) in vec3 position;"
"\n     layout(location = 1) in vec3 normal;"
"\n     layout(location = 2) in vec3 color;"
"\n     layout(location = 3) in vec2 uv;"
"\n "
"\n     void main()"
"\n     {"
"\n         v_color = color;"
"\n         v_normal = normal;"
"\n         v_light = transpose( mat3( view )) * normalize( vec3( 1 ));"
"\n         v_uv = uv;"
"\n "
"\n         gl_Position = projection * view * vec4( position, 1. );"
"\n     }"
"\n "
"\n #endif"
"\n #ifdef FRAGMENT"
"\n "
"\n     out vec4 color;"
"\n "
"\n     void main() "
"\n     {"
"\n         float light = .5 + .5 * clamp( dot( v_normal, v_light ), 0., 1. );"
"\n         vec4 texColor = texture2D( marioTex, v_uv );"
"\n         vec3 mainColor = mix( v_color, texColor.rgb, texColor.a ); // v_uv.x >= 0. ? texColor.a : 0. );"
"\n         color = vec4( mainColor * light, 1 );"
"\n     }"
"\n "
"\n #endif"
;
static const char *WORLD_SHADER =
"\n uniform mat4 model;"
"\n uniform mat4 view;"
"\n uniform mat4 projection;"
"\n uniform sampler2D tex;"
"\n "
"\n v2f vec3 v_normal;"
"\n v2f vec3 v_worldPos;"
"\n "
"\n #ifdef VERTEX"
"\n "
"\n     layout(location = 0) in vec3 position;"
"\n     layout(location = 1) in vec3 normal;"
"\n "
"\n     void main()"
"\n     {"
"\n         v_normal = inverse(mat3(model)) * normal;"
"\n         vec4 worldPos4 = model * vec4(position, 1.);"
"\n         v_worldPos = worldPos4.xyz;"
"\n         gl_Position = projection * view * worldPos4;"
"\n     }"
"\n "
"\n #endif"
"\n #ifdef FRAGMENT"
"\n "
"\n     vec3 tri( vec3 x )"
"\n     {"
"\n         return abs(x-floor(x)-.5);"
"\n     } "
"\n     float surfFunc( vec3 p )"
"\n     {"
"\n         float n = dot(tri(p*.15 + tri(p.yzx*.075)), vec3(.444));"
"\n         p = p*1.5773 - n;"
"\n         p.yz = vec2(p.y + p.z, p.z - p.y) * .866;"
"\n         p.xz = vec2(p.x + p.z, p.z - p.x) * .866;"
"\n         n += dot(tri(p*.225 + tri(p.yzx*.1125)), vec3(.222));     "
"\n         return abs(n-.5)*1.9 + (1.-abs(sin(n*9.)))*.05;"
"\n     }"
"\n "
"\n     const vec3 light_x = vec3(-1.0, 0.4, 0.9);"
"\n "
"\n     out vec4 color;"
"\n "
"\n     void main() "
"\n     {"
"\n         float surfy = surfFunc( v_worldPos / 50. );"
"\n         float brightness = smoothstep( .2, .3, surfy );"
"\n "
"\n         color = vec4( (0.5 + 0.25 * brightness) * (.5+.5*v_normal), 1 );"
"\n     }"
"\n "
"\n #endif"
;

static void load_collision_mesh( CollisionMesh *mesh )
{
	mesh->num_vertices = 3 * surfaces_count;
	mesh->position = malloc( sizeof( float ) * surfaces_count * 9 );
	mesh->normal = malloc( sizeof( float ) * surfaces_count * 9 );
	mesh->index = malloc( sizeof( uint16_t ) * surfaces_count * 3 );

	for( size_t i = 0; i < surfaces_count; ++i )
	{
		const struct SM64Surface *surf = &surfaces[i];

		float x1 = mesh->position[9*i+0] = surf->vertices[0][0];
		float y1 = mesh->position[9*i+1] = surf->vertices[0][1];
		float z1 = mesh->position[9*i+2] = surf->vertices[0][2];
		float x2 = mesh->position[9*i+3] = surf->vertices[1][0];
		float y2 = mesh->position[9*i+4] = surf->vertices[1][1];
		float z2 = mesh->position[9*i+5] = surf->vertices[1][2];
		float x3 = mesh->position[9*i+6] = surf->vertices[2][0];
		float y3 = mesh->position[9*i+7] = surf->vertices[2][1];
		float z3 = mesh->position[9*i+8] = surf->vertices[2][2];

		float nx = (y2 - y1) * (z3 - z2) - (z2 - z1) * (y3 - y2);
		float ny = (z2 - z1) * (x3 - x2) - (x2 - x1) * (z3 - z2);
		float nz = (x2 - x1) * (y3 - y2) - (y2 - y1) * (x3 - x2);
		float mag = sqrtf(nx * nx + ny * ny + nz * nz);
		nx /= mag;
		ny /= mag;
		nz /= mag;

		mesh->normal[9*i+0] = nx;
		mesh->normal[9*i+1] = ny;
		mesh->normal[9*i+2] = nz;
		mesh->normal[9*i+3] = nx;
		mesh->normal[9*i+4] = ny;
		mesh->normal[9*i+5] = nz;
		mesh->normal[9*i+6] = nx;
		mesh->normal[9*i+7] = ny;
		mesh->normal[9*i+8] = nz;

		mesh->index[3*i+0] = 3*i+0;
		mesh->index[3*i+1] = 3*i+1;
		mesh->index[3*i+2] = 3*i+2;
	}

	glGenVertexArrays( 1, &mesh->vao );
	glBindVertexArray( mesh->vao );

	#define X( loc, buff, arr, type ) do { \
		glGenBuffers( 1, &buff ); \
		glBindBuffer( GL_ARRAY_BUFFER, buff ); \
		glBufferData( GL_ARRAY_BUFFER, mesh->num_vertices*sizeof( type ), arr, GL_STATIC_DRAW ); \
		glEnableVertexAttribArray( loc ); \
		glVertexAttribPointer( loc, sizeof( type ) / sizeof( float ), GL_FLOAT, GL_FALSE, sizeof( type ), nullptr ); \
	} while( 0 )

		X( 0, mesh->position_buffer, mesh->position, vec3 );
		X( 1, mesh->normal_buffer,   mesh->normal,   vec3 );

	#undef X
}

static void load_mario_mesh( MarioMesh *mesh, struct SM64MarioGeometryBuffers *marioGeo )
{
	mesh->index = malloc( 3 * SM64_GEO_MAX_TRIANGLES * sizeof(uint16_t) );
	for( int i = 0; i < 3 * SM64_GEO_MAX_TRIANGLES; ++i )
		mesh->index[i] = i;

	mesh->num_vertices = 3 * SM64_GEO_MAX_TRIANGLES;

	glGenVertexArrays( 1, &mesh->vao );
	glBindVertexArray( mesh->vao );

	#define X( loc, buff, arr, type ) do { \
		glGenBuffers( 1, &buff ); \
		glBindBuffer( GL_ARRAY_BUFFER, buff ); \
		glBufferData( GL_ARRAY_BUFFER, sizeof( type ) * 3 * SM64_GEO_MAX_TRIANGLES, arr, GL_DYNAMIC_DRAW ); \
		glEnableVertexAttribArray( loc ); \
		glVertexAttribPointer( loc, sizeof( type ) / sizeof( float ), GL_FLOAT, GL_FALSE, sizeof( type ), nullptr ); \
	} while( 0 )

		X( 0, mesh->position_buffer, marioGeo->position, vec3 );
		X( 1, mesh->normal_buffer,   marioGeo->normal,   vec3 );
		X( 2, mesh->color_buffer,    marioGeo->color,    vec3 );
		X( 3, mesh->uv_buffer,       marioGeo->uv,       vec2 );

	#undef X
}

static void update_mario_mesh( MarioMesh *mesh, struct SM64MarioGeometryBuffers *marioGeo )
{
	if( mesh->index == nullptr )
		load_mario_mesh( mesh, marioGeo );

	mesh->num_vertices = 3 * marioGeo->numTrianglesUsed;

	glBindBuffer( GL_ARRAY_BUFFER, mesh->position_buffer );
	glBufferData( GL_ARRAY_BUFFER, sizeof( vec3 ) * 3 * SM64_GEO_MAX_TRIANGLES, marioGeo->position, GL_DYNAMIC_DRAW );
	glBindBuffer( GL_ARRAY_BUFFER, mesh->normal_buffer );
	glBufferData( GL_ARRAY_BUFFER, sizeof( vec3 ) * 3 * SM64_GEO_MAX_TRIANGLES, marioGeo->normal, GL_DYNAMIC_DRAW );
	glBindBuffer( GL_ARRAY_BUFFER, mesh->color_buffer );
	glBufferData( GL_ARRAY_BUFFER, sizeof( vec3 ) * 3 * SM64_GEO_MAX_TRIANGLES, marioGeo->color, GL_DYNAMIC_DRAW );
	glBindBuffer( GL_ARRAY_BUFFER, mesh->uv_buffer );
	glBufferData( GL_ARRAY_BUFFER, sizeof( vec2 ) * 3 * SM64_GEO_MAX_TRIANGLES, marioGeo->uv, GL_DYNAMIC_DRAW );
}

static GLuint shader_compile( const char *shaderContents, size_t shaderContentsLength, GLenum shaderType )
{
	const GLchar *shaderDefine = shaderType == GL_VERTEX_SHADER
		? "\n#version 330\n#define VERTEX  \n#define v2f out\n"
		: "\n#version 330\n#define FRAGMENT\n#define v2f in \n";

	const GLchar *shaderStrings[2] = { shaderDefine, shaderContents };
	GLint shaderStringLengths[2] = { strlen( shaderDefine ), (GLint)shaderContentsLength };

	GLuint shader = glCreateShader( shaderType );
	glShaderSource( shader, 2, shaderStrings, shaderStringLengths );
	glCompileShader( shader );

	GLint isCompiled;
	glGetShaderiv( shader, GL_COMPILE_STATUS, &isCompiled );
	if( isCompiled == GL_FALSE )
	{
		GLint maxLength;
		glGetShaderiv( shader, GL_INFO_LOG_LENGTH, &maxLength );
		char *log = (char*)malloc( maxLength );
		glGetShaderInfoLog( shader, maxLength, &maxLength, log );

		printf( "Error in shader: %s\n%s\n%s\n", log, shaderStrings[0], shaderStrings[1] );
		exit( 1 );
	}

	return shader;
}

static GLuint shader_load( const char *shaderContents )
{
	GLuint result;
	GLuint vert = shader_compile( shaderContents, strlen( shaderContents ), GL_VERTEX_SHADER );
	GLuint frag = shader_compile( shaderContents, strlen( shaderContents ), GL_FRAGMENT_SHADER );

	GLuint ref = glCreateProgram();
	glAttachShader( ref, vert );
	glAttachShader( ref, frag );

	glLinkProgram ( ref );
	glDetachShader( ref, vert );
	glDetachShader( ref, frag );
	result = ref;

	return result;
}

static void gl33core_init(RenderState *renderState, uint8_t *marioTexture)
{
	load_collision_mesh( &renderState->collision );
	renderState->world_shader = shader_load( WORLD_SHADER );
	renderState->mario_shader = shader_load( MARIO_SHADER );

	glEnable( GL_CULL_FACE );
	glCullFace( GL_BACK );
	glClearColor( 0.2f, 0.2f, 0.2f, 1.0f );
	glDepthMask( GL_TRUE );
	glDepthFunc( GL_LEQUAL );
	glEnable( GL_DEPTH_TEST );

	glGenTextures( 1, &renderState->mario_texture );
	glBindTexture( GL_TEXTURE_2D, renderState->mario_texture );
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, SM64_TEXTURE_WIDTH, SM64_TEXTURE_HEIGHT, 0, GL_RGBA, GL_UNSIGNED_BYTE, marioTexture);
}

static void gl33core_draw(RenderState *renderState, const vec3 camPos, const struct SM64MarioState *marioState, struct SM64MarioGeometryBuffers *marioGeo)
{
	update_mario_mesh( &renderState->mario, marioGeo );

	mat4 model, view, projection;
	glm_perspective( 45.0f, (float)WINDOW_WIDTH / (float)WINDOW_HEIGHT, 100.0f, 20000.0f, projection );
	glm_translate( view, (float*)camPos );
	glm_lookat( (float*)camPos, (float*)marioState->position, (vec3){0,1,0}, view );
	glm_mat4_identity( model );

	glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

	glUseProgram( renderState->world_shader );
	glBindVertexArray( renderState->collision.vao );
	glUniformMatrix4fv( glGetUniformLocation( renderState->world_shader, "model" ), 1, GL_FALSE, (GLfloat*)model );
	glUniformMatrix4fv( glGetUniformLocation( renderState->world_shader, "view" ), 1, GL_FALSE, (GLfloat*)view );
	glUniformMatrix4fv( glGetUniformLocation( renderState->world_shader, "projection" ), 1, GL_FALSE, (GLfloat*)projection );
	glDrawElements( GL_TRIANGLES, renderState->collision.num_vertices, GL_UNSIGNED_SHORT, renderState->collision.index );

	glUseProgram( renderState->mario_shader );
	glActiveTexture( GL_TEXTURE0 );
	glBindTexture( GL_TEXTURE_2D, renderState->mario_texture );
	glBindVertexArray( renderState->mario.vao );
	glUniformMatrix4fv( glGetUniformLocation( renderState->mario_shader, "view" ), 1, GL_FALSE, (GLfloat*)view );
	glUniformMatrix4fv( glGetUniformLocation( renderState->mario_shader, "projection" ), 1, GL_FALSE, (GLfloat*)projection );
	glUniform1i( glGetUniformLocation( renderState->mario_shader, "marioTex" ), 0 );
	glDrawElements( GL_TRIANGLES, renderState->mario.num_vertices, GL_UNSIGNED_SHORT, renderState->mario.index );
}

struct Renderer gl33core_renderer = {
    gl33core_init,
    gl33core_draw
};