use ::rltk::{Rltk, VirtualKeyCode};

use crate::rex_assets::RexAssets;
use crate::{colors, RunState, State};

#[derive(PartialEq, Copy, Clone)]
pub enum MainMenuSelection {
    NewGame,
    LoadGame,
    Quit,
}

#[derive(PartialEq, Copy, Clone)]
pub enum MainMenuResult {
    NoSelection { selected: MainMenuSelection },
    Selected { selected: MainMenuSelection },
}

pub fn main_menu(gs: &mut State, ctx: &mut Rltk) -> MainMenuResult {
    let save_exists = crate::saveload_system::does_save_exist();
    let runstate = gs.ecs.fetch::<RunState>();
    let assets = gs.ecs.fetch::<RexAssets>();
    ctx.render_xp_sprite(&assets.menu, 0, 0);

    ctx.draw_box_double(24, 18, 31, 10, colors::WHEAT, colors::BLACK);

    ctx.print_color_centered(20, colors::YELLOW, colors::BLACK, "Rust Roguelike");
    ctx.print_color_centered(21, colors::CYAN, colors::BLACK, "by Timothy J. Warren");
    ctx.print_color_centered(
        22,
        colors::GRAY,
        colors::BLACK,
        "Use Up/Down Arrows and Enter",
    );

    let mut y = 24;
    if let RunState::MainMenu {
        menu_selection: selection,
    } = *runstate
    {
        if selection == MainMenuSelection::NewGame {
            ctx.print_color_centered(y, colors::MAGENTA, colors::BLACK, "Begin New Game");
        } else {
            ctx.print_color_centered(y, colors::WHITE, colors::BLACK, "Begin New Game");
        }
        y += 1;

        if save_exists {
            if selection == MainMenuSelection::LoadGame {
                ctx.print_color_centered(y, colors::MAGENTA, colors::BLACK, "Load Game");
            } else {
                ctx.print_color_centered(y, colors::WHITE, colors::BLACK, "Load Game");
            }
            y += 1;
        }

        if selection == MainMenuSelection::Quit {
            ctx.print_color_centered(y, colors::MAGENTA, colors::BLACK, "Quit");
        } else {
            ctx.print_color_centered(y, colors::WHITE, colors::BLACK, "Quit");
        }

        return match ctx.key {
            None => MainMenuResult::NoSelection {
                selected: selection,
            },
            Some(key) => match key {
                VirtualKeyCode::Escape => MainMenuResult::NoSelection {
                    selected: MainMenuSelection::Quit,
                },
                VirtualKeyCode::Up => MainMenuResult::NoSelection {
                    selected: match selection {
                        MainMenuSelection::NewGame => MainMenuSelection::Quit,
                        MainMenuSelection::LoadGame => MainMenuSelection::NewGame,
                        MainMenuSelection::Quit => {
                            if save_exists {
                                MainMenuSelection::LoadGame
                            } else {
                                MainMenuSelection::NewGame
                            }
                        }
                    },
                },
                VirtualKeyCode::Down => MainMenuResult::NoSelection {
                    selected: match selection {
                        MainMenuSelection::NewGame => {
                            if save_exists {
                                MainMenuSelection::LoadGame
                            } else {
                                MainMenuSelection::Quit
                            }
                        }
                        MainMenuSelection::LoadGame => MainMenuSelection::Quit,
                        MainMenuSelection::Quit => MainMenuSelection::NewGame,
                    },
                },
                VirtualKeyCode::Return => MainMenuResult::Selected {
                    selected: selection,
                },
                _ => MainMenuResult::NoSelection {
                    selected: selection,
                },
            },
        };
    }

    MainMenuResult::NoSelection {
        selected: MainMenuSelection::NewGame,
    }
}