use std::collections::HashMap;

use rand::prelude::*;
use crate::entity::{Location, EntityId, Entity};
use crate::creature::{Creature, Profession, CreatureGenerator};
use crate::item::Item;
use crate::site::{Town, Tavern};
use crate::time::Time;
use crate::world::{World, Terrain};
use crate::events::{FoundTown, WorldGenesis, PersonGenesis, TavernBuilt};
pub struct GameState {
    pub time: Time,
    pub world: World,
    pub creatures: HashMap<u32, Creature>,
    pub items: HashMap<u32, Item>,
    pub events: Vec<Box<Event>>,
    pub tavern: Option<EntityId>,
}

pub struct Event {
    pub time: Time,
    pub effect: Box<dyn Action>,
}

pub trait Action {
    // apply the effect to the game state
    fn apply(&self, state: &mut GameState);
    // description of the event that will be displayed in the event log
    // TODO: thils needs a more complex return type.
    // A notable event needs to be related to entities
    fn description(&self) -> String;
    // if true, the event will be added to the event log
    // otherwise, it will only be used for internal purposes
    fn notable(&self) -> bool;
}

impl Event {
    #[allow(dead_code)]
    pub fn description(&self) -> String {
        format!("{}: {}", self.time, self.effect.description())
    }
}


impl GameState {
    pub fn new(world: World) -> GameState {
        let mut events = Vec::new();
        events.push(Box::new(Event {
            time: Time { time: 0 },
            effect: Box::new(WorldGenesis),
        }));

        GameState {
            time: Time { time: 0 },
            creatures: HashMap::new(),
            items: HashMap::new(),
            world: world,
            events: events,
            tavern: None,
        }
    }

    pub fn set_tavern(&mut self, tavern: EntityId) {
        self.tavern = Some(tavern);
    }

    pub fn add_event(&mut self, event: Event) {
        event.effect.apply(self);
        self.events.push(Box::new(event));
    }


    /**
     * Getters
     */

    pub fn guests(&self) -> Vec<EntityId> {
        match &self.tavern {
            Some(tavern) => {
                let loc = self.world.get_site_location(*tavern);
                self.creatures.values().filter(|c| {
                    c.entity.loc == loc
                }).map(|p| p.entity.id).collect::<Vec<_>>()
                // Vec::new()
            },
            None => Vec::new(),
        }   
    }

    pub fn get_creature(&self, id: u32) -> Option<&Creature> {
        self.creatures.get(&id)
    }


    /**
     * Function to populate the world at genesis
     */

    pub fn found_town(&mut self) {  
        let mut rng = rand::thread_rng();  
        loop {
            let x = rng.gen_range(0..self.world.size);
            let y = rng.gen_range(0..self.world.size);
            if 
                self.world.map[x][y].terrain == Terrain::Flats ||
                self.world.map[x][y].terrain == Terrain::Hills
            {
                let town = Town::new();
                self.add_event(Event {
                    time: self.time,
                    effect: Box::new(FoundTown {
                        loc: Location{ x: x as i32, y: y as i32 },
                        town: town.clone(),
                    })
                });

                let pop_size = rng.gen_range(20..200);

                for _ in 0..pop_size {
                    self.add_event(Event {
                        time: self.time,
                        effect: Box::new(PersonGenesis {
                            town: town.clone(),
                            person: CreatureGenerator::create_human(
                                self.time.substract_years(rng.gen_range(18..30)),
                                Location { x: x as i32, y: y as i32 },
                            )
                        })
                    });
                }
                break;
            }
        }
    }

    pub fn add_person(&mut self, mut creature: Creature) {
        let id = (self.creatures.len() + 1) as u32; // avoid 0 id
        creature.entity.id = id;
        self.creatures.insert(id, creature);
    }

    pub(crate) fn add_item(&mut self, mut item: Item) -> EntityId {
        let id = (self.items.len() + 1) as u32; // avoid 0 id
        item.entity.id = id;
        self.items.insert(id, item);
        id        
    }

    pub fn build_tavern(&mut self) {
        let mut rng = rand::thread_rng();  
        loop {
            let x = rng.gen_range(0..self.world.size);
            let y = rng.gen_range(0..self.world.size);
            if 
                self.world.map[x][y].terrain == Terrain::Flats ||
                self.world.map[x][y].terrain == Terrain::Hills
            {
                self.add_event(Event {
                    time: self.time,
                    effect: Box::new(TavernBuilt {
                        loc: Location{ x: x as i32, y: y as i32 },
                        tavern: Tavern::new(),
                    })
                });
                break;
            }
        }
    }

    pub fn claim_item(&mut self, new_owner_id: EntityId, item_id: EntityId) {
        let mut item = self.items.get_mut(&item_id).unwrap();
        item.owner = Some(new_owner_id.clone());
    }

}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_found_town() {
        let mut state = GameState::new(World::new(1));
        state.world.map[0][0].terrain = Terrain::Flats;
        state.time = Time { time: 1e6 as i32 };
        state.found_town();
        assert_ne!(state.creatures.len(), 0);
    }

    #[test]
    fn test_build_tavern() {
        let mut state = GameState::new(World::new(2));
        state.world.map[0][0].terrain = Terrain::Flats;
        state.world.map[0][1].terrain = Terrain::Flats;
        state.world.map[1][0].terrain = Terrain::Hills;
        state.world.map[1][1].terrain = Terrain::Hills;
        state.build_tavern();
        assert_eq!(state.tavern.is_some(), true);
    }

}