#include <catch2/catch_test_macros.hpp>

#include <string_view>
#include <variant>
#include <vector>

import ttwhy.core;
import ttwhy.terminal;

using namespace std::string_view_literals;

[[nodiscard]] constexpr auto static is_character(ttwhy::terminal::input_event & event, char expected) -> bool
{
  auto const * data = std::get_if<ttwhy::terminal::character_event>(&event);
  return data != nullptr && data->value == expected;
}

[[nodiscard]] constexpr auto static is_control(ttwhy::terminal::input_event & event,
                                               ttwhy::terminal::control_key expected) -> bool
{
  auto const * data = std::get_if<ttwhy::terminal::control_event>(&event);
  return data != nullptr && data->key == expected;
}

[[nodiscard]] constexpr auto static is_navigation(ttwhy::terminal::input_event const & event,
                                                  ttwhy::terminal::navigation_key expected_key,
                                                  ttwhy::terminal::modifier_set expected_modifiers = {}) -> bool
{
  auto const * data = std::get_if<ttwhy::terminal::navigation_event>(&event);
  return data != nullptr && data->key == expected_key && data->modifiers == expected_modifiers;
}

[[nodiscard]] constexpr auto static is_function(ttwhy::terminal::input_event const & event,
                                                ttwhy::terminal::function_key expected_key,
                                                ttwhy::terminal::modifier_set expected_modifiers = {}) -> bool
{
  auto const * data = std::get_if<ttwhy::terminal::function_key_event>(&event);
  return data != nullptr && data->key == expected_key && data->modifiers == expected_modifiers;
}

SCENARIO("The ANSI scanner processes printable ASCII and standard C0 control characters", "[scanner][ansi]")
{
  GIVEN("An initialized scanner and event sink")
  {
    auto queue = std::vector<ttwhy::terminal::input_event>{};
    auto sink = [&queue](auto const & event) {
      queue.push_back(event);
    };
    auto scanner = ttwhy::terminal::ansi{sink};

    WHEN("Processing a standard printable character")
    {
      scanner.process("A"sv);

      THEN("It yields a single character event")
      {
        REQUIRE(queue.size() == 1);
        CHECK(is_character(queue.at(0), 'A'));
      }
    }

    WHEN("Processing a BS byte (\\x08)")
    {
      scanner.process("\x08"sv);

      THEN("It yields a backspace control event")
      {
        REQUIRE(queue.size() == 1);
        CHECK(is_control(queue.at(0), ttwhy::terminal::control_key::backspace));
      }
    }

    WHEN("Processing a DEL byte (\\x7f as BS)")
    {
      scanner.process("\x7f"sv);

      THEN("It yields a backspace control event")
      {
        REQUIRE(queue.size() == 1);
        CHECK(is_control(queue.at(0), ttwhy::terminal::control_key::backspace));
      }
    }

    WHEN("Processing a TAB byte")
    {
      scanner.process("\x09"sv);

      THEN("It yields a tab control event")
      {
        REQUIRE(queue.size() == 1);
        CHECK(is_control(queue.at(0), ttwhy::terminal::control_key::tab));
      }
    }

    WHEN("Processing an LF byte")
    {
      scanner.process("\x0a"sv);

      THEN("It yields an enter control event")
      {
        REQUIRE(queue.size() == 1);
        CHECK(is_control(queue.at(0), ttwhy::terminal::control_key::enter));
      }
    }

    WHEN("Processing an CR byte")
    {
      scanner.process("\x0d"sv);

      THEN("It yields an enter control event")
      {
        REQUIRE(queue.size() == 1);
        CHECK(is_control(queue.at(0), ttwhy::terminal::control_key::enter));
      }
    }
  }
}

SCENARIO("The ANSI scanner processes VT220 keypad and cursor navigation sequences", "[scanner][ansi]")
{
  GIVEN("An initialized ANSI scanner and event sink")
  {
    auto queue = std::vector<ttwhy::terminal::input_event>{};
    auto sink = [&queue](auto const & event) {
      queue.push_back(event);
    };
    auto scanner = ttwhy::terminal::ansi{sink};

    WHEN("Processing VT220 keypad Home (\\x1b[1~)")
    {
      scanner.process("\x1b[1~"sv);

      THEN("It yields a navigation event for home")
      {
        REQUIRE(queue.size() == 1);
        CHECK(is_navigation(queue.at(0), ttwhy::terminal::navigation_key::home));
      }
    }

    WHEN("Processing VT220 keypad Insert (\\x1b[2~)")
    {
      scanner.process("\x1b[2~"sv);

      THEN("It yields a navigation event for insert")
      {
        REQUIRE(queue.size() == 1);
        CHECK(is_navigation(queue.at(0), ttwhy::terminal::navigation_key::insert_key));
      }
    }

    WHEN("Processing VT220 keypad Delete (\\x1b[3~)")
    {
      scanner.process("\x1b[3~"sv);

      THEN("It yields a navigation event for delete")
      {
        REQUIRE(queue.size() == 1);
        CHECK(is_navigation(queue.at(0), ttwhy::terminal::navigation_key::delete_key));
      }
    }

    WHEN("Processing VT220 keypad End (\\x1b[4~)")
    {
      scanner.process("\x1b[4~"sv);

      THEN("It yields a navigation event for end")
      {
        REQUIRE(queue.size() == 1);
        CHECK(is_navigation(queue.at(0), ttwhy::terminal::navigation_key::end));
      }
    }

    WHEN("Processing VT220 keypad Page Up (\\x1b[5~)")
    {
      scanner.process("\x1b[5~"sv);

      THEN("It yields a navigation event for page up")
      {
        REQUIRE(queue.size() == 1);
        CHECK(is_navigation(queue.at(0), ttwhy::terminal::navigation_key::page_up));
      }
    }

    WHEN("Processing VT220 keypad Page Down (\\x1b[6~)")
    {
      scanner.process("\x1b[6~"sv);

      THEN("It yields a navigation event for page down")
      {
        REQUIRE(queue.size() == 1);
        CHECK(is_navigation(queue.at(0), ttwhy::terminal::navigation_key::page_down));
      }
    }

    WHEN("Processing VT100 cursor arrows")
    {
      scanner.process("\x1b[A\x1b[B\x1b[C\x1b[D"sv);

      THEN("It yields navigation events for up, down, right, and left")
      {
        REQUIRE(queue.size() == 4);
        CHECK(is_navigation(queue.at(0), ttwhy::terminal::navigation_key::up));
        CHECK(is_navigation(queue.at(1), ttwhy::terminal::navigation_key::down));
        CHECK(is_navigation(queue.at(2), ttwhy::terminal::navigation_key::right));
        CHECK(is_navigation(queue.at(3), ttwhy::terminal::navigation_key::left));
      }
    }
  }
}

SCENARIO("The ANSI scanner processes multi-digit function keys and SS3 sequences", "[scanner][ansi]")
{
  GIVEN("An initialized ANSI scanner and event sink")
  {
    auto queue = std::vector<ttwhy::terminal::input_event>{};
    auto sink = [&queue](auto const & event) {
      queue.push_back(event);
    };
    auto scanner = ttwhy::terminal::ansi{sink};

    WHEN("Processing F1 (\\x1b[11~)")
    {
      scanner.process("\x1b[11~"sv);

      THEN("It yields a function key event for F1 and not home")
      {
        REQUIRE(queue.size() == 1);
        CHECK(is_function(queue.at(0), ttwhy::terminal::function_key::f1));
      }
    }

    WHEN("Processing F5 (\\x1b[15~)")
    {
      scanner.process("\x1b[15~"sv);

      THEN("It yields a function key event for F5 and not home")
      {
        REQUIRE(queue.size() == 1);
        CHECK(is_function(queue.at(0), ttwhy::terminal::function_key::f5));
      }
    }

    WHEN("Processing F6 (\\x1b[17~)")
    {
      scanner.process("\x1b[17~"sv);

      THEN("It yields a function key event for F6")
      {
        REQUIRE(queue.size() == 1);
        CHECK(is_function(queue.at(0), ttwhy::terminal::function_key::f6));
      }
    }

    WHEN("Processing F12 (\\x1b[24~)")
    {
      scanner.process("\x1b[24~"sv);

      THEN("It yields a function key event for F12")
      {
        REQUIRE(queue.size() == 1);
        CHECK(is_function(queue.at(0), ttwhy::terminal::function_key::f12));
      }
    }

    WHEN("Processing F20 (\\x1b[34~)")
    {
      scanner.process("\x1b[34~"sv);

      THEN("It yields a function key event for F20")
      {
        REQUIRE(queue.size() == 1);
        CHECK(is_function(queue.at(0), ttwhy::terminal::function_key::f20));
      }
    }

    WHEN("Processing an unmapped multi-digit code (\\x1b[99~)")
    {
      scanner.process("\x1b[99~"sv);

      THEN("No event is emitted")
      {
        CHECK(queue.empty());
      }
    }

    WHEN("Processing SS3 function keys F1 through F4 (\\x1bOP to \\x1bOS)")
    {
      scanner.process("\x1bOP\x1bOQ\x1bOR\x1bOS"sv);

      THEN("It yields function key events for F1 through F4")
      {
        REQUIRE(queue.size() == 4);
        CHECK(is_function(queue.at(0), ttwhy::terminal::function_key::f1));
        CHECK(is_function(queue.at(1), ttwhy::terminal::function_key::f2));
        CHECK(is_function(queue.at(2), ttwhy::terminal::function_key::f3));
        CHECK(is_function(queue.at(3), ttwhy::terminal::function_key::f4));
      }
    }
  }
}

SCENARIO("The xterm scanner decodes keypad sequences and function keys with modifiers", "[scanner][xterm]")
{
  GIVEN("An initialized xterm scanner and event sink")
  {
    auto queue = std::vector<ttwhy::terminal::input_event>{};
    auto sink = [&queue](auto const & event) {
      queue.push_back(event);
    };
    auto scanner = ttwhy::terminal::xterm{sink};

    WHEN("Processing Shift+Home (\\x1b[1;2~)")
    {
      scanner.process("\x1b[1;2~"sv);

      THEN("It yields a navigation event for Home with shift modifier")
      {
        REQUIRE(queue.size() == 1);
        CHECK(is_navigation(queue.at(0), ttwhy::terminal::navigation_key::home,
                            ttwhy::terminal::modifier::shift | ttwhy::terminal::modifier::none));
      }
    }

    WHEN("Processing Ctrl+Delete (\\x1b[3;5~)")
    {
      scanner.process("\x1b[3;5~"sv);

      THEN("It yields a navigation event for Delete with ctrl modifier")
      {
        REQUIRE(queue.size() == 1);
        CHECK(is_navigation(queue.at(0), ttwhy::terminal::navigation_key::delete_key,
                            ttwhy::terminal::modifier::ctrl | ttwhy::terminal::modifier::none));
      }
    }

    WHEN("Processing Shift+F5 (\\x1b[15;2~)")
    {
      scanner.process("\x1b[15;2~"sv);

      THEN("It yields a function key event for F5 with shift modifier")
      {
        REQUIRE(queue.size() == 1);
        CHECK(is_function(queue.at(0), ttwhy::terminal::function_key::f5,
                          ttwhy::terminal::modifier::shift | ttwhy::terminal::modifier::none));
      }
    }

    WHEN("Processing Ctrl+F5 (\\x1b[15;5~)")
    {
      scanner.process("\x1b[15;5~"sv);

      THEN("It yields a function key event for F5 with ctrl modifier")
      {
        REQUIRE(queue.size() == 1);
        CHECK(is_function(queue.at(0), ttwhy::terminal::function_key::f5,
                          ttwhy::terminal::modifier::ctrl | ttwhy::terminal::modifier::none));
      }
    }

    WHEN("Processing Alt+F12 (\\x1b[24;3~)")
    {
      scanner.process("\x1b[24;3~"sv);

      THEN("It yields a function key event for F12 with alt modifier")
      {
        REQUIRE(queue.size() == 1);
        CHECK(is_function(queue.at(0), ttwhy::terminal::function_key::f12,
                          ttwhy::terminal::modifier::alt | ttwhy::terminal::modifier::none));
      }
    }

    WHEN("Processing Shift+Up cursor (\\x1b[1;2A)")
    {
      scanner.process("\x1b[1;2A"sv);

      THEN("It yields a navigation event for Up with shift modifier")
      {
        REQUIRE(queue.size() == 1);
        CHECK(is_navigation(queue.at(0), ttwhy::terminal::navigation_key::up,
                            ttwhy::terminal::modifier::shift | ttwhy::terminal::modifier::none));
      }
    }
  }
}