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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 APP_HH
#define APP_HH

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

#include <boost/asio.hpp>

#include <cstddef>

#include <set>
#include <vector>
#include <string>
#include <thread>
#include <chrono>
#include <utility>
#include <sstream>
#include <iostream>
#include <unordered_map>

namespace Belle = OB::Belle;
namespace String = OB::String;
namespace iom = OB::Term::iomanip;
namespace aec = OB::Term::ANSI_Escape_Codes;

class App final
{
public:

  App() {}
  App(App&&) = delete;
  App(App const&) = delete;
  ~App() = default;

  App& operator=(App&&) = delete;
  App& operator=(App const&) = delete;

  void artists(std::vector<std::string> const& val_, bool const ignore_case_ = false);
  void color(bool const val_);
  void count(std::size_t const val_);
  void headers(std::vector<std::string> const& val_);
  void progress(bool const val_);

  void run();

private:

  void do_timer();
  void on_timer(Belle::error_code const& ec_);

  void update_wait();
  void update_progress();

  void signal_init();

  void http_init();
  void http_init_request();
  void http_next();
  void http_redirect(Belle::Client::Http::Session_Ctx const& ctx_);
  void http_close(std::string const& msg_ = {});

  void handle_results();

  void print_artist() const;
  void print_results() const;
  std::string artist_target(std::string const& artist_) const;

  // HTTP connect port
  unsigned short const _port {443};

  // HTTP connect address
  std::string const _address {"www.last.fm"};

  // artist regex
  std::string const _rx_artist {"href=\"/music/([^/]+?)\"\\s+"};

  // redirect regex
  std::regex const _rx_redirect {"^https://www.last.fm/music/(.+?)/\\+similar.*$", std::regex::icase};

  // total number of redirects to follow per artist
  std::size_t const _redirect_total {3};

  // total number of pages to request per artist
  std::size_t const _page_total {10};

  // update / timer interval
  std::chrono::milliseconds const _interval {100};

  // total request wait time
  std::chrono::milliseconds const _wait_total {1000};

  // progress output char values
  std::string const _progress_str {"-\\|/"};

  // artist result
  struct Result
  {
    // artist
    std::string artist;

    // artist in lowercase
    std::string artist_lowercase;

    // artist formatted for use in url
    std::string artist_url;

    // current page number
    std::size_t page_count {1};

    // number of redirects followed
    std::size_t redirect_count {0};

    // similar artist matches
    std::set<std::string> match;

    // insert ordered iterators to similar artist matches
    std::vector<decltype(match)::const_iterator> index;
  }; // struct Result

  using Results = std::vector<Result>;

  // artist results
  Results _results;

  // when true, use color in output
  bool _color {false};

  // when true, progress is output to stderr
  bool _progress {false};

  // total number of matches to find per artist
  std::size_t _match_total {0};

  // default HTTP request headers to use
  std::unordered_map<std::string, std::string> _headers {
    {"host", _address},
    {"dnt", "1"},
    {"pragma", "no-cache"},
    {"cache-control", "no-cache"},
    {"upgrade-insecure-requests", "1"},
    {"accept-encoding", "gzip,deflate"},
    {"accept-language", "en-US,en;q=0.9"},
    {"accept", "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8"},
    {"user-agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.142 Safari/537.36"},
  };

  // when true, reconnect socket if closed
  bool _reconnect {false};

  // HTTP response status code
  int _http_status {0};

  // current index position in the results
  std::size_t _result_index {0};

  // current request wait time
  std::chrono::milliseconds _wait_count {0};

  // current index position in the progress string
  std::size_t _progress_index {0};

  // buffer for HTTP response body
  std::string _page;

  // HTTP error message
  std::string _http_reason;

  // regex iterator
  OB::Text::Regex _it;

  // HTTP request, reused for each subsequent request
  Belle::Request _req;

  // io context
  Belle::io _io {1};

  // capture and handle signals
  Belle::Signal _sig {_io};

  // HTTP client
  Belle::Client::Http _http {_io, _address, _port, true};

  // timer for progress output
  Belle::net::high_resolution_timer _timer {_io, _interval};
}; // class App

#endif // APP_APP_HH