use rltk::{GameState, Point, Rltk};
use specs::prelude::*;
use specs::saveload::{SimpleMarker, SimpleMarkerAllocator};

mod components;
mod damage_system;
mod game_log;
mod gui;
mod hunger_system;
mod inventory_system;
mod map;
mod map_indexing_system;
mod melee_combat_system;
mod monster_ai_system;
mod particle_system;
mod player;
pub mod random_table;
mod rect;
mod rex_assets;
pub mod saveload_system;
mod spawner;
mod trigger_system;
mod visibility_system;

use crate::inventory_system::ItemRemoveSystem;
use components::*;
use damage_system::DamageSystem;
pub use game_log::GameLog;
use inventory_system::{ItemCollectionSystem, ItemDropSystem, ItemUseSystem};
pub use map::*;
use map_indexing_system::MapIndexingSystem;
use melee_combat_system::MeleeCombatSystem;
use monster_ai_system::MonsterAI;
use player::*;
pub use rect::Rect;
use visibility_system::VisibilitySystem;

/// Cut down on the amount of syntax to register components
macro_rules! register {
    // $gs is needed to get the scope at the usage point
    // $Type is the Component type that is being registered
    ($gs: ident <- $( $Type: ty ),*,) => {
        $(
            $gs.ecs.register::<$Type>();
        )*
    }
}

#[derive(PartialEq, Copy, Clone)]
pub enum RunState {
    AwaitingInput,
    PreRun,
    PlayerTurn,
    MonsterTurn,
    ShowInventory,
    ShowDropItem,
    ShowTargeting {
        range: i32,
        item: Entity,
    },
    MainMenu {
        menu_selection: gui::MainMenuSelection,
    },
    SaveGame,
    NextLevel,
    ShowRemoveItem,
    GameOver,
    MagicMapReveal {
        row: i32,
    },
}

pub struct State {
    pub ecs: World,
}

impl State {
    fn new() -> Self {
        State { ecs: World::new() }
    }

    fn run_systems(&mut self) {
        let mut vis = VisibilitySystem {};
        vis.run_now(&self.ecs);

        let mut mob = MonsterAI {};
        mob.run_now(&self.ecs);

        let mut triggers = trigger_system::TriggerSystem {};
        triggers.run_now(&self.ecs);

        let mut mapindex = MapIndexingSystem {};
        mapindex.run_now(&self.ecs);

        let mut melee = MeleeCombatSystem {};
        melee.run_now(&self.ecs);

        let mut damage = DamageSystem {};
        damage.run_now(&self.ecs);

        let mut pickup = ItemCollectionSystem {};
        pickup.run_now(&self.ecs);

        let mut items = ItemUseSystem {};
        items.run_now(&self.ecs);

        let mut drop_items = ItemDropSystem {};
        drop_items.run_now(&self.ecs);

        let mut item_remove = ItemRemoveSystem {};
        item_remove.run_now(&self.ecs);

        let mut hunger = hunger_system::HungerSystem {};
        hunger.run_now(&self.ecs);

        let mut particles = particle_system::ParticleSpawnSystem {};
        particles.run_now(&self.ecs);

        self.ecs.maintain();
    }
}

impl GameState for State {
    fn tick(&mut self, ctx: &mut Rltk) {
        let mut newrunstate;
        {
            let runstate = self.ecs.fetch::<RunState>();
            newrunstate = *runstate;
        }

        ctx.cls();
        particle_system::cull_dead_particles(&mut self.ecs, ctx);

        match newrunstate {
            RunState::MainMenu { .. } => {}
            RunState::GameOver { .. } => {}
            _ => {
                // Draw the UI
                draw_map(&self.ecs, ctx);
                {
                    let positions = self.ecs.read_storage::<Position>();
                    let renderables = self.ecs.read_storage::<Renderable>();
                    let hidden = self.ecs.read_storage::<Hidden>();
                    let map = self.ecs.fetch::<Map>();

                    let mut data: Vec<_> = (&positions, &renderables, !&hidden).join().collect();
                    data.sort_by(|&a, &b| b.1.render_order.cmp(&a.1.render_order));
                    for (pos, render, _hidden) in data.iter() {
                        let idx = map.xy_idx(pos.x, pos.y);

                        if map.visible_tiles[idx] {
                            ctx.set(pos.x, pos.y, render.fg, render.bg, render.glyph)
                        }
                    }

                    gui::draw_ui(&self.ecs, ctx);
                }
            }
        }

        match newrunstate {
            RunState::PreRun => {
                self.run_systems();
                self.ecs.maintain();
                newrunstate = RunState::AwaitingInput;
            }
            RunState::AwaitingInput => {
                newrunstate = player_input(self, ctx);
            }
            RunState::PlayerTurn => {
                self.run_systems();
                self.ecs.maintain();

                match *self.ecs.fetch::<RunState>() {
                    RunState::MagicMapReveal { .. } => {
                        newrunstate = RunState::MagicMapReveal { row: 0 }
                    }
                    _ => newrunstate = RunState::MonsterTurn,
                }
            }
            RunState::MonsterTurn => {
                self.run_systems();
                self.ecs.maintain();
                newrunstate = RunState::AwaitingInput;
            }
            RunState::ShowInventory => {
                let result = gui::show_inventory(self, ctx);
                match result.0 {
                    gui::ItemMenuResult::Cancel => newrunstate = RunState::AwaitingInput,
                    gui::ItemMenuResult::NoResponse => {}
                    gui::ItemMenuResult::Selected => {
                        let item_entity = result.1.unwrap();
                        let is_ranged = self.ecs.read_storage::<Ranged>();

                        if let Some(is_item_ranged) = is_ranged.get(item_entity) {
                            newrunstate = RunState::ShowTargeting {
                                range: is_item_ranged.range,
                                item: item_entity,
                            };
                        } else {
                            let mut intent = self.ecs.write_storage::<WantsToUseItem>();
                            intent
                                .insert(
                                    *self.ecs.fetch::<Entity>(),
                                    WantsToUseItem {
                                        item: item_entity,
                                        target: None,
                                    },
                                )
                                .expect("failed to add intent to use item");

                            newrunstate = RunState::PlayerTurn;
                        }
                    }
                }
            }
            RunState::ShowDropItem => {
                let result = gui::drop_item_menu(self, ctx);
                match result.0 {
                    gui::ItemMenuResult::Cancel => newrunstate = RunState::AwaitingInput,
                    gui::ItemMenuResult::NoResponse => {}
                    gui::ItemMenuResult::Selected => {
                        let item_entity = result.1.unwrap();
                        let mut intent = self.ecs.write_storage::<WantsToDropItem>();
                        intent
                            .insert(
                                *self.ecs.fetch::<Entity>(),
                                WantsToDropItem { item: item_entity },
                            )
                            .expect("failed to add intent to drop item");

                        newrunstate = RunState::PlayerTurn;
                    }
                }
            }
            RunState::ShowRemoveItem => {
                let result = gui::remove_item_menu(self, ctx);
                match result.0 {
                    gui::ItemMenuResult::Cancel => newrunstate = RunState::AwaitingInput,
                    gui::ItemMenuResult::NoResponse => {}
                    gui::ItemMenuResult::Selected => {
                        let item_entity = result.1.unwrap();
                        let mut intent = self.ecs.write_storage::<WantsToRemoveItem>();
                        intent
                            .insert(
                                *self.ecs.fetch::<Entity>(),
                                WantsToRemoveItem { item: item_entity },
                            )
                            .expect("Unable to insert intent to remove item");

                        newrunstate = RunState::PlayerTurn;
                    }
                }
            }
            RunState::ShowTargeting { range, item } => {
                let result = gui::ranged_target(self, ctx, range);
                match result.0 {
                    gui::ItemMenuResult::Cancel => newrunstate = RunState::AwaitingInput,
                    gui::ItemMenuResult::NoResponse => {}
                    gui::ItemMenuResult::Selected => {
                        let mut intent = self.ecs.write_storage::<WantsToUseItem>();

                        intent
                            .insert(
                                *self.ecs.fetch::<Entity>(),
                                WantsToUseItem {
                                    item,
                                    target: result.1,
                                },
                            )
                            .expect("failed to add intent to use item");

                        newrunstate = RunState::PlayerTurn;
                    }
                }
            }
            RunState::MainMenu { .. } => match gui::main_menu(self, ctx) {
                gui::MainMenuResult::NoSelection { selected } => {
                    newrunstate = RunState::MainMenu {
                        menu_selection: selected,
                    }
                }
                gui::MainMenuResult::Selected { selected } => match selected {
                    gui::MainMenuSelection::NewGame => newrunstate = RunState::PreRun,
                    gui::MainMenuSelection::LoadGame => {
                        saveload_system::load_game(&mut self.ecs);
                        newrunstate = RunState::AwaitingInput;
                        saveload_system::delete_save();
                    }
                    gui::MainMenuSelection::Quit => {
                        ::std::process::exit(0);
                    }
                },
            },
            RunState::GameOver => match gui::game_over(ctx) {
                gui::GameOverResult::NoSelection => {}
                gui::GameOverResult::QuitToMenu => {
                    self.game_over_cleanup();
                    newrunstate = RunState::MainMenu {
                        menu_selection: gui::MainMenuSelection::NewGame,
                    };
                }
            },
            RunState::SaveGame => {
                saveload_system::save_game(&mut self.ecs);

                newrunstate = RunState::MainMenu {
                    menu_selection: gui::MainMenuSelection::LoadGame,
                }
            }
            RunState::NextLevel => {
                self.goto_next_level();
                newrunstate = RunState::PreRun;
            }
            RunState::MagicMapReveal { row } => {
                let mut map = self.ecs.fetch_mut::<Map>();
                for x in 0..MAP_WIDTH {
                    let idx = map.xy_idx(x as i32, row);
                    map.revealed_tiles[idx] = true;
                }

                if row as usize == MAP_HEIGHT - 1 {
                    newrunstate = RunState::MonsterTurn;
                } else {
                    newrunstate = RunState::MagicMapReveal { row: row + 1 };
                }
            }
        }

        {
            let mut runwriter = self.ecs.write_resource::<RunState>();
            *runwriter = newrunstate;
        }

        damage_system::delete_the_dead(&mut self.ecs);
    }
}

impl State {
    fn entities_to_remove_on_level_change(&mut self) -> Vec<Entity> {
        let entities = self.ecs.entities();
        let player = self.ecs.read_storage::<Player>();
        let backpack = self.ecs.read_storage::<InBackpack>();
        let player_entity = self.ecs.fetch::<Entity>();
        let equipped = self.ecs.read_storage::<Equipped>();

        let mut to_delete: Vec<Entity> = Vec::new();
        for entity in entities.join() {
            let mut should_delete = true;

            // Don't delete the player
            if let Some(_p) = player.get(entity) {
                should_delete = false;
            }

            // Don't delete the player's equipment
            if let Some(bp) = backpack.get(entity) {
                if bp.owner == *player_entity {
                    should_delete = false;
                }
            }
            if let Some(eq) = equipped.get(entity) {
                if eq.owner == *player_entity {
                    should_delete = false;
                }
            }

            if should_delete {
                to_delete.push(entity);
            }
        }

        to_delete
    }

    fn goto_next_level(&mut self) {
        // Delete entities that aren't the palyer or their equipment
        let to_delete = self.entities_to_remove_on_level_change();
        for target in to_delete {
            self.ecs
                .delete_entity(target)
                .expect("failed to delete entity");
        }

        // Build a new map and place the player
        let worldmap;
        let current_depth;
        {
            let mut worldmap_resource = self.ecs.write_resource::<Map>();
            current_depth = worldmap_resource.depth;

            *worldmap_resource = Map::new_map_rooms_and_corridors(current_depth + 1);
            worldmap = worldmap_resource.clone();
        }

        // Spawn bad guys
        for room in worldmap.rooms.iter().skip(1) {
            spawner::spawn_room(&mut self.ecs, room, current_depth + 1);
        }

        // Place the player and update resources
        let (player_x, player_y) = worldmap.rooms[0].center();
        let mut player_position = self.ecs.write_resource::<Point>();
        *player_position = Point::new(player_x, player_y);
        let mut position_components = self.ecs.write_storage::<Position>();
        let player_entity = self.ecs.fetch::<Entity>();
        if let Some(player_pos_comp) = position_components.get_mut(*player_entity) {
            player_pos_comp.x = player_x;
            player_pos_comp.y = player_y;
        }

        // Mark the player's visibility as dirty
        let mut viewshed_components = self.ecs.write_storage::<Viewshed>();
        if let Some(vs) = viewshed_components.get_mut(*player_entity) {
            vs.dirty = true;
        }

        // Notify the player and give them some health
        let mut gamelog = self.ecs.fetch_mut::<GameLog>();
        gamelog
            .entries
            .push("You descend to the next level, and take a moment to heal.".to_string());
        let mut player_health_store = self.ecs.write_storage::<CombatStats>();
        let player_health = player_health_store.get_mut(*player_entity);
        if let Some(player_health) = player_health {
            player_health.hp = i32::max(player_health.hp, player_health.max_hp / 2);
        }
    }

    fn game_over_cleanup(&mut self) {
        // Delete everything
        let mut to_delete = Vec::new();
        for e in self.ecs.entities().join() {
            to_delete.push(e);
        }
        for del in to_delete.iter() {
            self.ecs
                .delete_entity(*del)
                .expect("Failed to delete entity");
        }

        // Build a new map and place the player
        let worldmap;
        {
            let mut worldmap_resource = self.ecs.write_resource::<Map>();
            *worldmap_resource = Map::new_map_rooms_and_corridors(1);
            worldmap = worldmap_resource.clone();
        }

        // Spawn bad guys
        for room in worldmap.rooms.iter().skip(1) {
            spawner::spawn_room(&mut self.ecs, room, 1);
        }

        // Place the player and update resources
        let (player_x, player_y) = worldmap.rooms[0].center();
        let player_entity = spawner::player(&mut self.ecs, player_x, player_y);
        let mut player_position = self.ecs.write_resource::<Point>();
        *player_position = Point::new(player_x, player_y);
        let mut position_components = self.ecs.write_storage::<Position>();
        let mut player_entity_writer = self.ecs.write_resource::<Entity>();
        *player_entity_writer = player_entity;
        if let Some(player_pos_comp) = position_components.get_mut(player_entity) {
            player_pos_comp.x = player_x;
            player_pos_comp.y = player_y;
        }

        // Mark the player's visibility as dirty
        let mut viewshed_components = self.ecs.write_storage::<Viewshed>();
        let vs = viewshed_components.get_mut(player_entity);
        if let Some(vs) = vs {
            vs.dirty = true;
        }
    }
}

fn main() -> rltk::BError {
    use rltk::RltkBuilder;

    let context = RltkBuilder::simple80x50()
        .with_title("Roguelike Tutorial")
        .build()?;

    let mut gs = State::new();

    register!(
        gs <-
        Position,
        Renderable,
        Player,
        Viewshed,
        Monster,
        Name,
        BlocksTile,
        CombatStats,
        WantsToMelee,
        SufferDamage,
        Item,
        ProvidesHealing,
        InBackpack,
        WantsToPickupItem,
        WantsToUseItem,
        WantsToDropItem,
        Consumable,
        Ranged,
        InflictsDamage,
        AreaOfEffect,
        Confusion,
        SimpleMarker<SerializeMe>,
        SerializationHelper,
        Equippable,
        Equipped,
        MeleePowerBonus,
        DefenseBonus,
        WantsToRemoveItem,
        ParticleLifetime,
        HungerClock,
        ProvidesFood,
        MagicMapper,
        Hidden,
        EntryTrigger,
        EntityMoved,
    );

    gs.ecs.insert(SimpleMarkerAllocator::<SerializeMe>::new());

    let map = Map::new_map_rooms_and_corridors(1);
    let (player_x, player_y) = map.rooms[0].center();

    let player_entity = spawner::player(&mut gs.ecs, player_x, player_y);

    gs.ecs.insert(rltk::RandomNumberGenerator::new());
    for room in map.rooms.iter().skip(1) {
        spawner::spawn_room(&mut gs.ecs, room, 1);
    }

    gs.ecs.insert(map);
    gs.ecs.insert(Point::new(player_x, player_y));
    gs.ecs.insert(player_entity);
    gs.ecs.insert(RunState::MainMenu {
        menu_selection: gui::MainMenuSelection::NewGame,
    });
    gs.ecs.insert(GameLog::new("Welcome to Rusty Roguelike"));
    gs.ecs.insert(particle_system::ParticleBuilder::new());
    gs.ecs.insert(rex_assets::RexAssets::new());

    rltk::main_loop(context, gs)
}