/*
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                                   OCTOBANANA

Licensed under the MIT License

Copyright (c) 2019 Brett Robinson <https://octobanana.com/>

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/

#ifndef OB_READLINE_HH
#define OB_READLINE_HH

#include "ob/term.hh"
#include "ob/text.hh"
#include "ob/string.hh"

#include <cstddef>

#include <stack>
#include <deque>
#include <vector>
#include <string>
#include <limits>
#include <fstream>
#include <filesystem>

namespace OB
{

namespace fs = std::filesystem;
namespace aec = OB::Term::ANSI_Escape_Codes;

class Readline
{
public:

  Readline() = default;

  friend std::ostream& operator<<(std::ostream& os, Readline const& obj);

  void autocomplete(std::function<std::vector<std::string>()> const& val_);
  void boundaries(std::string const& val_);
  std::string word_under_cursor(std::string const& delimiters);
  Readline& style(std::string const& style_ = {});
  Readline& prompt(std::string const& str_, std::string const& style_ = {});
  Readline& size(std::size_t const width_, std::size_t const height_);
  bool operator()(OB::Text::Char32 input);
  std::string render() const;
  std::string get();
  Readline& clear();
  Readline& refresh();
  Readline& normal();

  void hist_push(std::string const& str);
  void hist_load(fs::path const& path);

// private:

  // cursor
  void curs_begin();
  void curs_end();
  void curs_left();
  void curs_right();

  // edit
  void edit_clear();
  bool edit_delete();
  void edit_insert(std::string const& str);
  bool edit_backspace();
  // TODO autopair should not run when pasting
  void edit_insert_autopair(OB::Text::Char32 const& val);
  void edit_backspace_autopair();

  // history
  void hist_prev();
  void hist_next();
  void hist_reset();
  void hist_search(std::string const& str);
  void hist_open(fs::path const& path);
  void hist_save(std::string const& str);

  // autocomplete
  void ac_init();
  void ac_sync();
  void ac_begin();
  void ac_end();
  void ac_prev();
  void ac_next();
  void ac_prev_section();
  void ac_next_section();

  std::string normalize(std::string const& str) const;

  enum class Mode
  {
    normal,
    history_init,
    history,
    autocomplete_init,
    autocomplete,
  };

  void mode(Mode const mode_);

  Mode _mode {Mode::normal};
  Mode _mode_prev {Mode::normal};

  std::string _boundaries {" "};

  // width and height of the terminal
  std::size_t _width {0};
  std::size_t _height {0};

  std::string _res;

  struct Style
  {
    std::string prompt;
    std::string input;
  } _style;

  struct Prompt
  {
    std::string lhs;
    std::string rhs;
    std::string fmt;
    std::string str {":"};
  } _prompt;

  struct Input
  {
    bool save_local {true};
    bool save_file {true};
    bool clear_input {false};
    std::size_t offp {0};
    std::size_t idxp {0};
    std::size_t off {0};
    std::size_t idx {0};
    std::size_t cur {0};
    std::string buf;
    std::string clipboard;
    OB::Text::String str;
    OB::Text::String fmt;
  } _input;

  struct History
  {
    static std::size_t constexpr npos {std::numeric_limits<std::size_t>::max()};

    struct Search
    {
      struct Result
      {
        Result(std::size_t s, std::size_t i) noexcept :
          score {s},
          idx {i}
        {
        }

        std::size_t score {0};
        std::size_t idx {0};
      };

      using value_type = std::deque<Result>;

      value_type& operator()()
      {
        return val;
      }

      bool empty()
      {
        return val.empty();
      }

      void clear()
      {
        idx = History::npos;
        val.clear();
      }

      std::size_t idx {0};
      value_type val;
    } search;

    using value_type = std::deque<std::string>;

    value_type& operator()()
    {
      return val;
    }

    value_type val;
    std::size_t idx {npos};

    std::ofstream file;
  } _history;

  struct Autocomplete
  {
    friend std::ostream& operator<<(std::ostream& os, Autocomplete const& obj)
    {
      os << obj.render();

      return os;
    }

    void width(std::size_t const width_)
    {
      _width = width_;
    }

    std::string render() const
    {
      return _value;
    }

    Autocomplete& refresh()
    {
      _lhs = _off ? "<" : "";
      _rhs = _off + _max != _match.size() ? ">" : " ";

      std::ostringstream ss;

      for (std::size_t i = 0, n = _off ? 1ul : 0ul; i < _max; ++i)
      {
        if (i == _idx)
        {
          _hli = n;
          _hls = _view.at(i + _off).cols();
          ss << _match.at(i + _off);
        }
        else
        {
          ss << _match.at(i + _off);
        }

        if (i + 1 < _max)
        {
          ss << " ";
        }

        if (i < _idx)
        {
          n += _view.at(i + _off).cols() + 1;
        }
      }

      _text = ss.str();

      return *this;
    }

    // Autocomplete& refresh()
    // {
    //   std::ostringstream ss;

    //   if (_off)
    //   {
    //     ss
    //     << aec::clear
    //     << _style.prompt
    //     << "<"
    //     << aec::clear
    //     << _style.normal
    //     << OB::String::repeat(_width - 2, aec::space)
    //     << aec::clear
    //     << _style.prompt
    //     << (_off + _max != _match.size() ? ">" : " ")
    //     << aec::clear
    //     << _style.normal
    //     << aec::cr << aec::cursor_right(1);
    //   }
    //   else
    //   {
    //     ss
    //     << aec::clear
    //     << _style.normal
    //     << OB::String::repeat(_width - 1, aec::space)
    //     << aec::clear
    //     << _style.prompt
    //     << (_off + _max != _match.size() ? ">" : " ")
    //     << aec::clear
    //     << _style.normal
    //     << aec::cr;
    //   }

    //   for (std::size_t i = 0; i < _max; ++i)
    //   {
    //     if (i == _idx)
    //     {
    //       ss
    //       << aec::clear
    //       << _style.select
    //       << _match.at(i + _off)
    //       << aec::clear
    //       << _style.normal;
    //     }
    //     else
    //     {
    //       ss
    //       << _match.at(i + _off);
    //     }

    //     if (i + 1 < _max)
    //     {
    //       ss
    //       << aec::space;
    //     }
    //   }

    //   ss
    //   << aec::clear;

    //   _value = ss.str();

    //   return *this;
    // }

    Autocomplete& begin()
    {
      // move to begin of list
      // idx = 0
      // off = 0
      while (_off)
      {
        prev_section();
      }

      return *this;
    }

    Autocomplete& end()
    {
      while (_off + _max < _match.size())
      {
        next_section();
      }

      return *this;
    }

    Autocomplete& next()
    {
      if (_idx + 1 < _max)
      {
        ++_idx;
      }
      else if (_off + _max < _match.size())
      {
        _off += _max;
        _maxp.push(_max);
        setup();
      }

      return *this;
    }

    Autocomplete& prev()
    {
      if (_idx)
      {
        --_idx;
      }
      else if (_off)
      {
        _off -= _maxp.top();
        _maxp.pop();
        setup();
        _idx = _max - 1;
      }

      return *this;
    }

    Autocomplete& next_section()
    {
      _idx = _max - 1;
      next();

      return *this;
    }

    Autocomplete& prev_section()
    {
      _idx = 0;
      prev();
      _idx = 0;

      return *this;
    }

    void setup()
    {
      _idx = 0;
      _max = 0;

      if (_view.empty())
      {
        return;
      }

      std::size_t constexpr space {1};
      std::size_t len {_off ? 1ul : 0ul};
      std::size_t tmp {len};
      for (std::size_t i = 0; i < _view.size() && _off + i < _view.size(); ++i, ++_max)
      {
        tmp += _view.at(_off + i).cols() + space;
        if (tmp > _width)
        {
          break;
        }
        len += tmp;
      }
    }

    Autocomplete& word(std::string const& str_)
    {
      _word = str_;

      return *this;
    }

    std::string const& word()
    {
      return _word;
    }

    // call each time autocomplete mode is entered
    Autocomplete& generate()
    {
      _idx = 0;
      _off = 0;
      _max = 0;
      _maxp = {};
      _match.clear();
      _view.clear();

      if (! _update)
      {
        return *this;
      }

      // TODO remove duplicates there could be same named vars in different scopes
      if (_word.size())
      {
        _match = find_similar(_word, _update());
      }
      else
      {
        _match = _update();
        std::sort(_match.begin(), _match.end(),
        [](auto const& lhs, auto const& rhs)
        {
          return (lhs.size() == rhs.size()) ?
            (lhs < rhs) :
            (lhs.size() < rhs.size());
        });
      }

      for (auto const& e : _match)
      {
        _view.emplace_back(OB::Text::View(e));
      }

      setup();

      return *this;
    }

    std::vector<std::string> find_similar(
      std::string const& key, std::vector<std::string> const& values) const
    {
      int const weight_max {8};
      size_t const similar_max {1024};

      // TODO use single vec and erase elements that are > weight_max
      std::vector<std::string> results;
      std::vector<std::pair<int, std::string>> dist;

      for (auto const& val : values)
      {
        if (val.size() < key.size())
        {
          continue;
        }

        int const weight = OB::String::starts_with(val, key) ? 0 :
          OB::String::damerau_levenshtein(key, val, 1, 2, 4, 0);

        if (weight < weight_max)
        {
          dist.emplace_back(weight, val);
        }
      }

      std::sort(dist.begin(), dist.end(),
      [](auto const& lhs, auto const& rhs)
      {
        return (lhs.first == rhs.first) ?
          (lhs.second.size() == rhs.second.size() ?
           lhs.second < rhs.second :
           lhs.second.size() < rhs.second.size()) :
          (lhs.first < rhs.first);
      });

      for (auto const& [key, val] : dist)
      {
        results.emplace_back(val);
      }

      if (results.size() > similar_max)
      {
        results.erase(results.begin() + similar_max, results.end());
      }

      return results;
    }

    struct Style
    {
      std::string prompt;
      std::string normal;
      std::string select {aec::reverse};
    } _style;

    std::size_t _hli {0}; // highlight index
    std::size_t _hls {0}; // highlight size
    std::string _lhs;
    std::string _rhs;
    std::string _text;

    // string value
    std::string _value;

    // word to autocomplete on
    std::string _word;

    // word offset
    std::size_t _off {0};

    // current selected word index
    std::size_t _idx {0};

    // current max number of words that fit on the current screen width
    std::size_t _max {0};

    // previous max number of words that fit on the current screen width
    std::stack<std::size_t> _maxp;

    // screen width
    std::size_t _width {0};

    std::vector<std::string> _match;
    std::vector<OB::Text::View> _view;
    std::function<std::vector<std::string>()> _update;
  } _autocomplete;
};

} // namespace OB

#endif // OB_READLINE_HH