Heil

#include "ast.hpp"

#include <regex>

int32_t Interpret(
    InterpretContext &context, // Contains the parameters and variable bindings
    TreePtr program
){
    std::regex reNum("^-?[0-9]+$");
    std::regex reId("^[a-z][a-z 0-9]*$");

    if( regex_match(program->type, reNum) ){
        return std::atol(program->type.c_str());

    // TODO : Check for things matching reId
    }
    else if( regex_match(program->type, reId) ){
        return context.bindings[program->type.c_str()];

    }
    else if(program->type=="Param"){
        unsigned index=atol(program->value.c_str());
        auto value=context.params.at(index);
        return value;

    }
    else if(program->type=="Assign"){ //Works
        int32_t val = Interpret(context, program->branches.at(0));
        context.bindings[program->value.c_str()] = val;
        return val;
    }
    else if(program->type=="Input"){
        int32_t val;
        std::cin >> val;
        return val;
    }
    else if(program->type=="Output"){
        int32_t val=Interpret(context, program->branches.at(0));
        std::cout<<val<<std::endl;
        return val;

    // TODO: Handle other constructs

    }
    else if(program->type=="While"){
        while(Interpret(context, program->branches.at(0)) != 0){
            Interpret(context, program->branches.at(1));
        }
        return 0;
    }
    else if(program->type=="Seq"){ //Works
        int32_t val;
        int vecsize = program->branches.size();
        for(int i = 0; i < vecsize; i++){
            val = Interpret(context, program->branches.at(i));
        }
        return val;
    }
    else if(program->type=="Add"){
        int32_t leftval = Interpret(context, program->branches.at(0));
        int32_t rightval = Interpret(context, program->branches.at(1));
        int32_t val = leftval + rightval;
        return val;
    }
    else if(program->type=="Sub"){
        int32_t leftval = Interpret(context, program->branches.at(0));
        int32_t rightval = Interpret(context, program->branches.at(1));
        int32_t val = leftval - rightval;
        return val;
    }
    else if(program->type=="If"){
        int32_t val;
        if(Interpret(context, program->branches.at(0)) != 0){
            val = Interpret(context, program->branches.at(1));
        }
        else {
            val = Interpret(context, program->branches.at(2));
        }
        return val;
    }
    else if(program->type=="LessThan"){
        int32_t val;
        if(Interpret(context, program->branches.at(0)) < Interpret(context, program->branches.at(1))){
            return 1;
        }
        else {
            return 0;
        }
    }
    else{
        throw std::runtime_error("Unknown construct '"+program->type+"'");
    }
}