#pragma once

#include "../../DataView.hpp"
#include "ShaderVec.hpp"
#include <string>
#include <unordered_map>
#include <vector>
#include <stdexcept>
#include <functional>

namespace amalgine
{
    class VertexShaderTooManyAttributes : public std::runtime_error
    {
    public:
        VertexShaderTooManyAttributes(i32 maxVertexAttributes);
    };
    
    class VertexShaderAttributeAlreadyDefined : public std::runtime_error
    {
    public:
        VertexShaderAttributeAlreadyDefined(const std::string &attributeName);
    };
    
    class VertexShaderInvalidAttributeName : public std::runtime_error
    {
    public:
        VertexShaderInvalidAttributeName(const std::string &attributeName);
    };
    
    class VertexShaderFunctionAlreadyDefined : public std::runtime_error
    {
    public:
        VertexShaderFunctionAlreadyDefined(const std::string &funcName);
    };
    
    using VertexShaderMainFunc = std::function<ShaderVec4()>;
    
    /*
     * Using the same VertexShader instance in multiple threads to define data is not thread safe.
     * All get*** functions are thread safe.
     */
    class VertexShader
    {
    public:
        VertexShader();
        
        const std::string& getInputAttributeName(i32 attributeIndex);
        ShaderInputVec2 defineInputVec2(const std::string &name);
        void defineMain(VertexShaderMainFunc mainFunc);
        std::string build() const;
    private:
        void writeHeader(const std::string &code);
        void writeBody(const std::string &code);
        
        /*
         * Throws VertexShaderTooManyInputAttributes if too many vertex attributes are defined for the platform.
         * Throws VertexShaderAttributeAlreadyDefined if a vertex attribute with the same name has already been defined.
         */
        i32 defineInputVariable(const std::string &variableName, const char *typeName);
    private:
        std::string header;
        std::string body;
        int locationCounter;
        i32 maxVertexAttribs; // Could make this static
        std::unordered_map<std::string, i32> vertexAttributes;
        std::vector<std::string> vertexAttributeNames;
        bool mainFuncDefined;
    };
}