#include <iostream>
#include <string>
#include <vector>
#include <unordered_map>
#include <variant>
#include <exception>
#include <memory>
#include <sstream>
#include <functional>
#include "pilang.hpp"



namespace Pilang3 {
    std::unordered_map<std::string, std::tuple<Cmdfnc, uint16_t, std::vector<Variable::Type>, bool>> builtinCmds = {
        {"concat", {[] (Environment& env, Cmdargs& args) {
                       std::ostringstream fres;
                       for (const auto& arg : args) {
                           switch (arg.type) {
                               case Variable::id_integer: fres << std::get<integer_type>(arg.data); break;
                               case Variable::id_string: fres << std::get<std::string>(arg.data); break;
                               case Variable::id_reference: fres << std::get<SharedVariable>(arg.data).get(); break;
                               case Variable::id_type: fres << std::get<Variable::Type>(arg.data); break;
                               default: fres << "<ID" << arg.type << '>'; break;
                           }
                       }
                       return Variable({
                           Variable::id_string,
                           fres.str()
                       });
        }, 0, {}, true}}
    };

    Evaluation::Evaluation(Environment& env, const std::string &expression, const bool autoeval) {
        // Parse arguments if any
        if (not expression.empty()) {
            Variable thisarg;
            bool in_command_name = true;
            bool newarg = false;
            bool escapenext = false;
            std::string cache;
            for (auto characterit = expression.begin(); characterit != expression.end(); characterit++) {
                char character = *characterit;
                // Start new command name
                if (in_command_name) {
                    if (character != ' ' and character != '\n' and character != ';') {
                        cache.push_back(character);
                    } else {
                        command_name = cache;
                        cache.clear();
                        if (character == ';') {
                            break;
                        } else {
                            in_command_name = false;
                            newarg = true;
                        }
                    }
                }
                // Start new argument
                else if (newarg) {
                    // Skip spaces
                    if (character == ' ' or character == ',' or character == '\n' or character == ';') continue;
                    // Guess type by first character
                    newarg = false;
                    if (std::isdigit(character) or character == '-' or character == '+') {
                        // Integer
                        thisarg.type = Variable::id_integer;
                        goto parsechar;
                    } else if (character == '"') {
                        // String
                        thisarg.type = Variable::id_string;
                    } else if (character == '&') {
                        // Expression
                        thisarg.type = Variable::id_evaluation;
                    } else {
                        // Reference
                        thisarg.type = Variable::id_reference;
                        goto parsechar;
                    }
                } else {
                    parsechar:
                    bool maybe_end_of_arg = character == ',' or character == ';';
                    // Do whatever (depends on type)
                    switch (thisarg.type) {
                        case Variable::id_integer: {
                            // Integer
                            if (character == ' ') continue;
                            else if (maybe_end_of_arg) {
                                // End argument
                                try {
                                    thisarg.data = integer_type(std::stoi(cache));
                                } catch (std::invalid_argument&) {
                                    throw exceptions::BadInteger();
                                }
                                newarg = true;
                            } else {
                                cache.push_back(character);
                            }
                        } break;
                        case Variable::id_string: {
                            // String
                            if (character == '\\' and not escapenext) {
                                escapenext = true;
                            } else if (character == '"' and not escapenext) {
                                thisarg.data = cache;
                                newarg = true;
                                character = *(++characterit);
                            } else {
                                cache.push_back(character);
                            }
                        } break;
                    case Variable::id_reference: {
                        // Reference
                        if (maybe_end_of_arg) {
                            auto res = env.globalVars.find(cache);
                            if (res == env.globalVars.end()) {
                                throw exceptions::NoSuchVariable();
                            }
                            thisarg = *res->second;
                            newarg = true;
                        } else {
                            cache.push_back(character);
                        }
                    } break;
                    case Variable::id_evaluation: {
                        // Check for exclaimation mark
                        bool noexec = *characterit == '!';
                        if (noexec) {
                            // Skip exclaimation mark if required
                            characterit++;
                        }
                        // Evaluate
                        auto evaluation = std::make_shared<Evaluation>(env, std::string(characterit, expression.end()));
                        // Execute if possible
                        if (autoeval and not noexec) {
                            thisarg = evaluation->execute(env);
                        } else {
                            thisarg.data = evaluation;
                        }
                        // Skip over expression in iteration
                        character = *(characterit += evaluation->exprlen + 1);
                        newarg = true;
                    } break;
                    }
                    // Actually end argument if required
                    if (newarg) {
                        arguments.push_back(thisarg);
                        cache.clear();
                        // Check if end of command was reached
                        if (character == ';') {
                            exprlen = std::distance(expression.begin(), characterit);
                            break;
                        }
                    }
                }
            }
            // Find command
            auto res = Pilang3::builtinCmds.find(command_name);
            if (res == Pilang3::builtinCmds.end()) {
                throw exceptions::NoSuchCommand();
            }
            uint16_t argslen;
            std::vector<Variable::Type> argstypes;
            bool anymoreopts;
            std::tie(command, argslen, argstypes, anymoreopts) = res->second;
            // Check args
            if ((arguments.size() > argslen and not anymoreopts) or (arguments.size() < argslen)) {
                throw exceptions::BadArgs();
            }
            for (uint16_t argidx = 0; argidx != argslen; argidx++) {
                if (argstypes[argidx] != Variable::id_any and argstypes[argidx] != arguments[argidx].type) {
                    throw exceptions::BadArgs();
                }
            }
        }
    }

    Variable Evaluation::execute(Environment& env) {
        if (command) {
            return command(env, arguments);
        } else {
            throw exceptions::NoSuchCommand();
        }
    }
};