use crate::error::Result;
use std::path::Path;
use geoffrey_models::GeoffreyDatabaseModel;
use crate::{u64_from_bytes, u64_to_bytes};
use sled::Iter;

pub struct Database {
    db: sled::Db,
}

impl Database {
    pub fn new(db_path: &Path) -> Result<Self> {
        let db = sled::open(db_path)?;

        Ok(Self {
            db,
        })
    }

    fn get_tree<T>(&self) -> Result<sled::Tree> where T: GeoffreyDatabaseModel {
        Ok(self.db.open_tree::<String>(T::tree())?)
    }

    pub fn insert<T>(&self, mut model: T) -> Result<T> where T: GeoffreyDatabaseModel {
        let id = match model.id() {
            Some(id) => id,
            None => {
                let id = self.db.generate_id()?;
                model.set_id(id);
                id
            }
        };

        let tree = self.get_tree::<T>()?;
        let id_bytes = u64_to_bytes(id);

        tree.insert(id_bytes, model.to_bytes()?)?;

        Ok(model)
    }


    pub fn get<T>(&self, id: u64) -> Result<Option<T>> where T: GeoffreyDatabaseModel {
        let tree = self.get_tree::<T>()?;
        let id_bytes = u64_to_bytes(id);

        if let Some(bytes) = tree.get(id_bytes)? {
            Ok(Some(T::try_from_bytes(&bytes)?))
        }
        else {
            Ok(None)
        }

    }

    pub fn filter<T, F>(&self, f: F) -> Result<Vec<T>> where T: GeoffreyDatabaseModel, F: Fn(u64, &T) -> bool {
        let tree = self.db.open_tree(T::tree())?;

        Ok(tree.iter().filter_map(|e| {
            if let Ok((id, data)) = e {
                let id = u64_from_bytes(&mut id.clone());
                let data = T::try_from_bytes(&data).unwrap();

                if f(id, &data) {
                    Some(data)
                }
                else {
                    None
                }
            }
            else {
                None
            }
        }).collect())
    }

    pub fn tree_iter<T>(&self) -> Result<Iter> where T: GeoffreyDatabaseModel {
        Ok(self.db.open_tree(T::tree()).map(|tree| tree.iter())?)
    }
}

#[cfg(test)]
mod tests {
    use crate::database::{Database};
    use std::path::Path;
    use geoffrey_models::models::player::{Player, UserID};
    use lazy_static::lazy_static;
    use geoffrey_models::GeoffreyDatabaseModel;

    lazy_static! {
        static ref DB: Database = Database::new(Path::new("../locations")).unwrap();
    }

    fn cleanup() {
        DB.db.clear().unwrap();
    }

    #[test]
    fn test_insert() {
        let player = Player::new("CoolZero123", UserID::DiscordUUID(0u64));

        let p2 = DB.insert::<Player>(player.clone()).unwrap();

        assert!(p2.id().is_some());
        assert_eq!(player.name, p2.name);
        cleanup();
    }

    #[test]
    fn test_get() {
        let player = Player::new("CoolZero123", UserID::DiscordUUID(0u64));

        let p2 = DB.insert::<Player>(player.clone()).unwrap();

        let p3 = DB.get::<Player>(p2.id().unwrap()).unwrap();

        assert!(p3.is_some());
        assert_eq!(p3.unwrap().name, player.name);
        cleanup();
    }
}