#ifndef wg_LEXER_HPP
#define wg_LEXER_HPP

#include "commons.hpp"
#include "Node.hpp"
#include "Loc.hpp"

namespace wg
{
  struct ScanInfo {
    size_t cursor;
    NodeType type;
    std::string repr;
  };

  using scanner_t = std::function<std::optional<ScanInfo>()>;

  class Lexer
  {
  public:
    explicit Lexer();
    virtual ~Lexer();

    void scan(std::string const& source);
    std::shared_ptr<Node> next();
    std::vector<std::shared_ptr<Node>> all();

  private:
    std::string m_source;
    size_t m_cursor = 0;
    Loc m_loc;
    std::vector<scanner_t> m_scanners;
    std::vector<char> m_seps;

    void add_text(std::string const& text,
                  NodeType node,
                  bool has_value=false);

    void add_keyword(std::string const& text,
                     NodeType node,
                     bool has_value=false);

    bool is_sep(size_t index) const;

    void skip_spaces();

    std::optional<ScanInfo> scan_text(std::string const& text,
                                      NodeType type,
                                      bool has_value) const;

    std::optional<ScanInfo> scan_keyword(std::string const& text,
                                         NodeType type,
                                         bool has_value) const;

    std::optional<ScanInfo> scan_ident() const;
    std::optional<ScanInfo> scan_int() const;
  };
}

#endif