//
//  main.cpp
//  stateful_dice
//
//  Created by Sam Jaffe on 12/18/18.
//  Copyright © 2018 Sam Jaffe. All rights reserved.
//

#include <fstream>
#include <iostream>
#include <map>
#include <regex>

#include "dice-roll/exception.h"

void usage() {
  std::cout << "'help'      : Print this message\n";
  std::cout << "'A := Dice' : Create a substitution pattern\n";
  std::cout << "'1d6+$Dex'  : Roll 1d6 plus whatever value subs for 'Dex'\n";
}

void print_binding_os(std::pair<const std::string, std::string> const & pair,
                      std::ostream & os) {
  os << pair.first;
  if (pair.second == "")
    os << " is not defined\n";
  else
    os << " := " << pair.second << "\n";
}

void print_binding(std::pair<const std::string, std::string> const & pair) {
  print_binding_os(pair, std::cout);
}

class evaluator {
public:
  evaluator(std::string const & path = "") {
    if (!path.empty()) { load(path); }
  }
  void operator()(std::string const & str);

private:
  using binding_t = std::map<std::string, std::string>;

  bool regex_search(char const * regex) {
    return std::regex_match(curr, match, std::regex(regex));
  }

  binding_t::value_type find_or(std::string const & key) const {
    auto it = bindings.find(key);
    return it == bindings.cend() ? binding_t::value_type(key, "") : *it;
  }

  void save(std::string const & file) const {
    using namespace std::placeholders;
    std::ofstream out(file);
    std::for_each(bindings.begin(), bindings.end(),
                  std::bind(&print_binding_os, _1, std::ref(out)));
  }
  void load(std::string const & file) {
    std::ifstream in(file);
    while (std::getline(in, curr)) {
      if (regex_search(R"(^(\w+)\s*:=\s*(.*)$)")) {
        bindings[match[1]] = match[2];
      }
    }
  }

private:
  std::string curr;
  std::smatch match;
  binding_t bindings;
};

void evaluator::operator()(std::string const & str) {
  curr = str;
  try {
    if (regex_search(R"(help|\?)")) {
      usage();
    } else if (regex_search(R"(^(\w+)\s*:=\s*(.*)$)")) {
      bindings[match[1]] = match[2];
    } else if (regex_search(R"(^show (\*|all))")) {
      std::for_each(bindings.begin(), bindings.end(), &print_binding);
    } else if (regex_search(R"(^show (\w+))")) {
      print_binding(find_or(match[1]));
    } else if (regex_search(R"(^unset (\*|all))")) {
      bindings.clear();
    } else if (regex_search(R"(^unset (\w+))")) {
      bindings.erase(match[1]);
    } else if (regex_search(R"(^save (.+))")) {
      save(match[1]);
    } else if (regex_search(R"(^load new (.+))")) {
      bindings.clear();
      load(match[1]);
    } else if (regex_search(R"(^load (.+))")) {
      load(match[1]);
    } else {
      while (regex_search(R"(.*(\$\w+).*)")) {
        curr.replace(match[1].first, match[1].second,
                     find_or(match[1].str().substr(1)).second);
      }
      auto d = dice::from_string(curr);
      auto rs = dice::roller()(d);
      std::cout << std::make_pair(d, rs) << '\n';
    }
  } catch (dice::unexpected_token const & ut) {
    std::cerr << "Error in roll: '" << curr << "': " << ut.what() << "\n";
    std::cerr << "                " << ut.pointer(str.size() + 1) << std::endl;
  }
}

int main(int argc, const char * argv[]) {
  std::string line;
  std::cout << "> ";
  evaluator eval(argc > 1 ? argv[1] : "");
  while (std::getline(std::cin, line)) {
    eval(line);
    std::cout << "> ";
  }
  return 0;
}