use crate::error::{JDbError, Result};
use crate::metadata::DBMetadata;
use crate::model::JdbModel;
use crate::query::QueryBuilder;
use json::JsonValue;
use sled::IVec;
use std::convert::TryInto;
use std::path::Path;

pub const DB_METADATA_ID: u64 = 1;

fn option_bytes_to_model<T: JdbModel>(bytes: Option<IVec>, id: u64) -> Result<T> {
    if let Some(bytes) = bytes {
        Ok(T::try_from_bytes(&bytes)?)
    } else {
        log::debug!("{} of id {} was not found in the database", T::tree(), id);
        Err(JDbError::NotFound)
    }
}

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

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

        let version = match db.version() {
            Ok(version) => version,
            Err(_) => {
                let db_metadata = DBMetadata {
                    id: Some(DB_METADATA_ID),
                    version: 0,
                };
                db.insert(db_metadata)?.version
            }
        };

        log::info!("jDb Version V{}", version);

        Ok(db)
    }

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

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

        let match_count = self
            .filter(|o_id, o: &T| o_id != id && !o.check_unique(&model))?
            .count();

        if match_count > 0 {
            log::debug!("{} is not unique: {:?}", T::tree(), model);
            return Err(JDbError::NotUnique);
        }

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

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

        Ok(model)
    }

    pub fn get<T>(&self, id: u64) -> Result<T>
    where
        T: JdbModel,
    {
        let tree = self.get_tree::<T>()?;
        option_bytes_to_model(tree.get(id.to_be_bytes())?, id)
    }

    pub fn clear_tree<T>(&self) -> Result<()>
    where
        T: JdbModel,
    {
        self.db.drop_tree(T::tree())?;

        Ok(())
    }

    pub fn filter<'a, T>(
        &self,
        f: impl Fn(u64, &T) -> bool + 'a,
    ) -> Result<impl Iterator<Item = T> + 'a>
    where
        T: JdbModel,
    {
        let tree = self.db.open_tree(T::tree())?;

        Ok(tree.iter().filter_map(move |e| {
            if let Ok((id, data)) = e {
                let id = u64::from_be_bytes(id.to_vec().try_into().unwrap());
                let data = match T::try_from_bytes(&data) {
                    Ok(data) => data,
                    Err(err) => {
                        log::debug!(
                            "Invalid data: {}",
                            String::from_utf8(data.to_vec()).unwrap_or_default()
                        );
                        panic!("Unable to parse {} model from bytes: {}", T::tree(), err);
                    }
                };

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

    pub fn run_query<T>(&self, query_builder: QueryBuilder<T>) -> Result<Vec<T>>
    where
        T: JdbModel,
    {
        let result: Vec<T> = self
            .filter(|id, loc: &T| {
                for query in &query_builder.queries {
                    let res = query(id, loc);

                    if !res {
                        return false;
                    }
                }

                true
            })?
            .collect();

        if result.is_empty() {
            Err(JDbError::NotFound)
        } else {
            Ok(result)
        }
    }

    pub fn remove<T>(&self, id: u64) -> Result<T>
    where
        T: JdbModel,
    {
        let tree = self.db.open_tree(T::tree())?;
        option_bytes_to_model(tree.remove(id.to_be_bytes())?, id)
    }

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

    pub fn version(&self) -> Result<u64> {
        Ok(self.get::<DBMetadata>(DB_METADATA_ID)?.version)
    }

    pub(crate) fn set_version(&mut self, version: u64) -> Result<()> {
        let mut md = self.get::<DBMetadata>(DB_METADATA_ID)?;

        md.version = version;

        self.insert(md)?;

        Ok(())
    }

    pub fn dump_db(&self) -> Result<JsonValue> {
        let mut json = JsonValue::new_object();

        let mut global_array = JsonValue::new_array();
        for model in self.db.iter() {
            let (_, model) = model?;
            let model_str = String::from_utf8(model.to_vec()).unwrap();
            let model_json = json::parse(&model_str)?;
            global_array.push(json::from(model_json))?;
        }

        json.insert("global", global_array)?;

        for tree in self.db.tree_names() {
            let tree = self.db.open_tree(tree)?;
            let mut tree_array = JsonValue::new_array();

            for model in tree.iter() {
                let (_, model) = model?;
                let model_str = String::from_utf8(model.to_vec()).unwrap();
                let model_json = json::parse(&model_str)?;
                tree_array.push(json::from(model_json))?;
            }

            let tree_name = String::from_utf8(tree.name().to_vec()).unwrap();
            json.insert(&tree_name, tree_array)?;
        }

        Ok(json)
    }

    pub fn import_db(&self, json: JsonValue) -> Result<()> {
        for model in json["global"].members() {
            let id_bytes = model["id"].as_u64().unwrap().to_be_bytes();
            self.db.insert(id_bytes, model.to_string().as_bytes())?;
        }

        for (tree, models) in json.entries() {
            for model in models.members() {
                let id_bytes = model["id"].as_u64().unwrap().to_be_bytes();

                if tree == "global" {
                    self.db.insert(id_bytes, model.to_string().as_bytes())?;
                } else {
                    let tree = self.db.open_tree(tree)?;
                    tree.insert(id_bytes, model.to_string().as_bytes())?;
                }
            }
        }

        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use crate::model::JdbModel;
    use crate::test::{cleanup, User, DB, LOCK};
    use std::time::Instant;

    #[test]
    fn test_insert() {
        let _lock = LOCK.lock().unwrap();
        cleanup();
        let user = User::new("Test", 1);

        let user2 = DB.insert::<User>(user.clone()).unwrap();

        assert!(user2.id().is_some());
        assert_eq!(user.name, user2.name);

        cleanup();
    }

    #[test]
    fn test_unique_insert() {
        let _lock = LOCK.lock().unwrap();
        cleanup();
        let user1 = User::new("Test", 1);
        let user2 = User::new("Test", 1);

        DB.insert::<User>(user1.clone()).unwrap();
        assert_eq!(DB.insert::<User>(user2.clone()).is_err(), true);

        cleanup();
    }

    #[test]
    fn test_get() {
        let _lock = LOCK.lock().unwrap();
        cleanup();
        let user1 = User::new("Test", 1);

        let user1_db = DB.insert::<User>(user1.clone()).unwrap();

        let user1_get = DB.get::<User>(user1_db.id().unwrap()).unwrap();

        assert_eq!(user1_get.name, user1.name);
        cleanup();
    }

    #[test]
    fn test_filter() {
        let _lock = LOCK.lock().unwrap();
        cleanup();
        let user = User::new("Test", 1);
        let user = DB.insert::<User>(user.clone()).unwrap();

        let count = DB
            .filter(|id: u64, u: &User| {
                assert_eq!(id, user.id().unwrap());
                u.id().unwrap() == user.id().unwrap()
            })
            .unwrap()
            .count();

        assert_eq!(count, 1);
        cleanup();
    }

    #[test]
    fn test_remove() {
        let _lock = LOCK.lock().unwrap();
        cleanup();
        let user = User::new("CoolZero123", 1);

        let user_insert = DB.insert::<User>(user.clone()).unwrap();

        let user_remove = DB.remove::<User>(user_insert.id().unwrap()).unwrap();

        assert!(DB.get::<User>(user_insert.id().unwrap()).is_err());
        assert_eq!(user_remove.id().unwrap(), user_insert.id().unwrap());
        cleanup();
    }

    #[test]
    fn test_speed() {
        let _lock = LOCK.lock().unwrap();
        cleanup();
        let insert_count = 1000;
        let timer = Instant::now();
        for i in 0..insert_count {
            let user = User::new(&format!("User{}", i), 0);

            DB.insert::<User>(user).unwrap();
        }

        DB.db.flush().unwrap();
        let sec_elapsed = timer.elapsed().as_secs_f32();
        println!(
            "Completed in {}s. {} inserts per second",
            sec_elapsed,
            insert_count as f32 / sec_elapsed
        );

        cleanup()
    }

    #[test]
    fn test_dump_and_load() {
        let _lock = LOCK.lock().unwrap();
        cleanup();

        let mut users = vec![];
        for i in 0..10 {
            let user = User::new(&format!("User{}", i), 0);

            let u = DB.insert::<User>(user).unwrap();

            users.push(u);
        }

        let out = DB.dump_db().unwrap();

        println!("{}", out);

        DB.import_db(out).unwrap();

        for user in users {
            let import_user = DB.get::<User>(user.id().unwrap()).unwrap();
            assert_eq!(user.name, import_user.name);
        }

        cleanup();
    }
}