#include <lua.hpp>
#include <libqalculate/qalculate.h>
#include <vector>
#include <string>

EvaluationOptions user_evaluation_options = default_evaluation_options;
PrintOptions user_print_options = default_print_options;

struct Output_struct {
    char * result;
    std::vector<char *> messages;
};

Output_struct qalculate(const char* input, bool exact_mode, bool interval_mode, bool structuring_mode) {
    // Create and prepare calculator
    Calculator* c = new Calculator();
    c->loadExchangeRates();
    c->loadGlobalDefinitions();
    c->loadLocalDefinitions();
    // Create input and output string buffers
    std::string Input = input;
    std::string Output;
    // Check evaluation options
    user_evaluation_options.structuring = (structuring_mode ?
        STRUCTURING_FACTORIZE :
        STRUCTURING_EXPAND);
    user_evaluation_options.interval_calculation = (interval_mode ?
        INTERVAL_CALCULATION_VARIANCE_FORMULA :
        INTERVAL_CALCULATION_NONE);
    user_evaluation_options.approximation = (exact_mode ? 
        APPROXIMATION_EXACT :
        APPROXIMATION_APPROXIMATE);
    user_print_options.number_fraction_format = (exact_mode ?
        FRACTION_DECIMAL_EXACT :
        FRACTION_DECIMAL);
    user_print_options.interval_display = (interval_mode ? 
        INTERVAL_DISPLAY_INTERVAL :
        INTERVAL_DISPLAY_MIDPOINT);
    // Prepare output struct
    struct Output_struct output;
    memset(&output,0,sizeof(Output_struct));
    // Evaluate and record result in Output
    Output = c->calculateAndPrint(Input,2000,user_evaluation_options,user_print_options);
    // record messages
    std::string current_msg;
    while (c->message() != NULL) {
        current_msg = c->message()->message();
        output.messages.push_back(new char[current_msg.size()+1]);
        current_msg.copy(output.messages.back(),current_msg.size());
        output.messages.back()[current_msg.size()] = "\0"[0];
        c->nextMessage();
    }
    delete c;
    // Copy result to the output structure
    output.result = new char [Output.length()+1];
    Output.copy(output.result,Output.length());
    output.result[Output.length()] = "\0"[0];
    return output;
}

extern "C" 
int l_qalc(lua_State* L) {
    const char * input = luaL_checkstring(L, 1);
    bool exact_mode = lua_toboolean(L, 2);
    bool interval_mode = lua_toboolean(L, 3);
    bool struct_mode = lua_toboolean(L, 4);
    Output_struct output = qalculate(input, exact_mode, interval_mode, struct_mode);
    lua_pushstring(L, output.result);
    lua_newtable(L);
    for (int i = 0; i < output.messages.size(); i++) {
        lua_pushstring(L, output.messages[i]);
        lua_rawseti(L, -2, i+1);
    }
    return 2;
}

extern "C"
int luaopen_libqalculator(lua_State* L) {
    static const struct luaL_Reg library [] =
    {
        {"qalc", l_qalc},
        {NULL, NULL}
    };
    luaL_register(L, "qalc", library);
    return 1;
}