#pragma once

#include <map>
#include <string>

#include <time.h>
#include <GL/glew.h>

#include <glm/glm.hpp>
#include <glm/gtc/type_ptr.hpp>

#include <SDL.h>

class ShaderProgram
{
	/* TODO there's gotta be a better way of doing this! */
	std::string mVertexPath, mGeometryPath, mFragmentPath;
	SDL_TimerID mShaderWatchTimer;
	/* most recent modification times for the three in order */
	time_t mMtime[3];

	bool mUniformLocationsNeedRefresh;
	std::map<const std::string, GLint> UniformLocationCache;

	static GLint my_checkCompileSuccess (const GLuint, const GLenum);
	static Uint32 my_WatchShaderHelper (Uint32 interval, void* param);

	GLint getCachedLoc (const std::string&);

	public:
		/*
		 * Set-able
		 */
		GLuint ID;

		ShaderProgram (const std::string&, const std::string&, const std::string&);

		~ShaderProgram (void);

		/*
		 * gl* stuff. These modify the current `ID`.
		 */
		void RefreshUniformLocations (void);
		void Use   (void);
		void Bool  (const std::string&, const bool&);
		void Float (const std::string&, const float&);
		void Int   (const std::string&, const int&);
		void Vec2  (const std::string&, const glm::vec2&);
		void Vec3  (const std::string&, const glm::vec3&);
		void Vec4  (const std::string&, const glm::vec4&);
		void Mat2  (const std::string&, const glm::mat2&);
		void Mat3  (const std::string&, const glm::mat3&);
		void Mat4  (const std::string&, const glm::mat4&);

		/*
		 * Program/util stuff
		 */
		GLuint CompileShaderBuffer (const std::string&, const GLenum);
		GLuint Compile3ShaderBuffers (const std::string&, const std::string&, const std::string&);
		GLuint CompileShaderPath (const std::string&, const GLenum);
		GLint LinkProgram (void);

		/*
		 * Monitor the modification time of the loaded shaders
		 */
		void StartWatchingShader (void);
		void StopWatchingShader (void);
		bool NeedsReloading (bool);

		const std::string& getVertexPath (void) const { return mVertexPath; }
		const std::string& getGeometryPath (void) const { return mGeometryPath; }
		const std::string& getFragmentPath (void) const { return mFragmentPath; }
};