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

extern crate serde;

mod components;
pub use components::*;
mod map;
pub use map::*;
mod player;
use player::*;
mod rect;
pub use rect::Rect;
mod visibility_system;
use visibility_system::VisibilitySystem;
mod monster_ai_system;
use monster_ai_system::MonsterAI;
mod map_indexing_system;
use map_indexing_system::MapIndexingSystem;
mod melee_combat_system;
use melee_combat_system::MeleeCombatSystem;
mod damage_system;
use damage_system::DamageSystem;
mod gui;
mod gamelog;
use gamelog::GameLog;
mod spawner;
mod inventory_system;
use inventory_system::*;
mod saveload_system;
mod random_table;
use random_table::*;
mod particle_system;
use particle_system::ParticleBuilder;

// ***** //
// STATE //

#[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,
}

pub struct State {
    pub ecs: World,
}

impl State {
    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 mapindex = MapIndexingSystem{};
        mapindex.run_now(&self.ecs);
        let mut mcs = MeleeCombatSystem{};
        mcs.run_now(&self.ecs);
        let mut dmgs = DamageSystem{};
        dmgs.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 particles = particle_system::ParticleSpawnSystem{};
        particles.run_now(&self.ecs);
        self.ecs.maintain();
    }

    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
            let p = player.get(entity);
            if let Some(_p) = p {
                should_delete = false;
            }

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

            // Don't delete items currently equipped by the player
            let eq = equipped.get(entity);
            if let Some(eq) = eq {
                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 player or his/her equipment
        let to_delete = self.entities_to_remove_on_level_change();
        for target in to_delete {
            self.ecs.delete_entity(target).expect("Unable 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);
        }
    
        // 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>();
        let player_pos_comp = position_components.get_mut(*player_entity);
        if let Some(player_pos_comp) = player_pos_comp {
            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;
        }        
    
        // Notify the player and give them some health
        let mut gamelog = self.ecs.fetch_mut::<gamelog::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("Deletion failed");
        }
    
        // 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;
        let player_pos_comp = position_components.get_mut(player_entity);
        if let Some(player_pos_comp) = player_pos_comp {
            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;
        }                                               
    }
}

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{..} => {}
            _ => {
                draw_map(&self.ecs, ctx);

                {
                    let positions = self.ecs.read_storage::<Position>();
                    let renderables = self.ecs.read_storage::<Renderable>();
                    let map = self.ecs.fetch::<Map>();

                    let mut data = (&positions, &renderables).join().collect::<Vec<_>>();
                    data.sort_by(|&a, &b| b.1.render_order.cmp(&a.1.render_order) );
                    for (pos, render) 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();
                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>();
                        let is_item_ranged = is_ranged.get(item_entity);
                        if let Some(is_item_ranged) = is_item_ranged {
                            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("Unable to insert intent");
                            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("Unable to insert intent");
                        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("Unable to insert intent");
                        newrunstate = RunState::PlayerTurn;
                    }
                }
            }
            RunState::MainMenu{ .. } => {
                let result = gui::main_menu(self, ctx);
                match result {
                    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::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::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");
                        newrunstate = RunState::PlayerTurn;
                    }
                }
            }
            RunState::GameOver => {
                let result = gui::game_over(ctx);
                match result {
                    gui::GameOverResult::NoSelection => {}
                    gui::GameOverResult::QuitToMenu => {
                        self.game_over_cleanup();
                        newrunstate = RunState::MainMenu{ menu_selection: gui::MainMenuSelection::NewGame };
                    }
                }
            }
        }

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

    }
}

// ********
// MAIN

fn main() -> rltk::BError {
    use rltk::RltkBuilder;
    let context = RltkBuilder::simple80x50()
        .with_title("Saint Antony's Fire")
        .build()?;
    // Add scanlines
    //context.with_post_scanlines(true);

    let mut gs = State{ 
        ecs: World::new(),
    };

    gs.ecs.register::<Position>();
    gs.ecs.register::<Renderable>();
    gs.ecs.register::<Player>();
    gs.ecs.register::<Viewshed>();
    gs.ecs.register::<Monster>();
    gs.ecs.register::<Name>();
    gs.ecs.register::<BlocksTile>();
    gs.ecs.register::<CombatStats>();
    gs.ecs.register::<WantsToMelee>();
    gs.ecs.register::<SufferDamage>();
    gs.ecs.register::<Item>();
    gs.ecs.register::<InBackpack>();
    gs.ecs.register::<WantsToPickupItem>();
    gs.ecs.register::<WantsToUseItem>();
    gs.ecs.register::<ProvidesHealing>();
    gs.ecs.register::<WantsToDropItem>();
    gs.ecs.register::<Consumable>();
    gs.ecs.register::<Ranged>();
    gs.ecs.register::<InflictsDamage>();
    gs.ecs.register::<AreaOfEffect>();
    gs.ecs.register::<SimpleMarker<SerializeMe>>();
    gs.ecs.register::<SerializationHelper>();
    gs.ecs.register::<Equippable>();
    gs.ecs.register::<Equipped>();
    gs.ecs.register::<MeleePowerBonus>();
    gs.ecs.register::<DefenseBonus>();
    gs.ecs.register::<WantsToRemoveItem>();
    gs.ecs.register::<ParticleLifetime>();

    // Resource to dispatch particle effects requests
    gs.ecs.insert(particle_system::ParticleBuilder::new());

    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(player_entity);

    let rng = rltk::RandomNumberGenerator::new();
    gs.ecs.insert(rng);

    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(RunState::MainMenu{ menu_selection: gui::MainMenuSelection::NewGame });

    gs.ecs.insert(gamelog::GameLog{ entries : vec!["Saint Antony casts out...".to_string()] });

    rltk::main_loop(context, gs)
}