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use crate::{entity::EntityID, Entity, Error, QueryInterface, WithID};
use std::hash::Hasher;

/// Any query that can be completed/executed
pub trait Resolvable<'r, 'q>: super::build::QueryComponent
where
    'q: 'r,
{
    type Output;

    fn qi(&self) -> &'r QueryInterface<'q>;

    fn exec(self) -> Result<(), Error>
    where
        Self: Sized,
    {
        self.no_result()
    }
    fn one(self) -> Result<Option<WithID<Self::Output>>, Error>
    where
        Self: Sized,
        Self::Output: Entity,
    {
        self.result()
    }
    fn one_id(self) -> Result<Option<Self::Output>, Error>
    where
        Self: Sized,
        Self::Output: EntityID,
    {
        self.id_result()
    }
    fn all(self) -> Result<Vec<WithID<Self::Output>>, Error>
    where
        Self: Sized,
        Self::Output: Entity,
    {
        self.results()
    }
    fn all_ids(self) -> Result<Vec<Self::Output>, Error>
    where
        Self: Sized,
        Self::Output: EntityID,
    {
        self.id_results()
    }

    fn no_result(self) -> Result<(), Error>
    where
        Self: Sized,
    {
        let mut hasher = std::collections::hash_map::DefaultHasher::new();
        self.contribute(&mut hasher);

        self.qi().with_cache(
            hasher.finish(),
            || self.qi().db.conn.prepare(self.derive().assemble()).unwrap(),
            |stmt| {
                self.bind(stmt)?;

                self.qi().expect_no_result(stmt)
            },
        )?
    }

    fn result(self) -> Result<Option<WithID<Self::Output>>, Error>
    where
        Self: Sized,
        Self::Output: Entity,
    {
        let mut hasher = std::collections::hash_map::DefaultHasher::new();
        self.contribute(&mut hasher);
        self.qi().with_cache(
            hasher.finish(),
            || {
                let query = self.derive().assemble();
                self.qi().db.conn.prepare(query).unwrap()
            },
            |stmt| {
                self.bind(stmt)?;

                self.qi().expect_one_result(stmt, &mut |stmt| {
                    let id: i64 = stmt.read(0)?;
                    Ok(WithID::wrap(Self::Output::build_from(stmt)?, id))
                })
            },
        )?
    }

    fn id_result(self) -> Result<Option<Self::Output>, Error>
    where
        Self: Sized,
        Self::Output: EntityID,
    {
        let mut hasher = std::collections::hash_map::DefaultHasher::new();
        self.contribute(&mut hasher);
        self.qi().with_cache(
            hasher.finish(),
            || {
                let query = self.derive().assemble();
                self.qi().db.conn.prepare(query).unwrap()
            },
            |stmt| {
                self.bind(stmt)?;

                self.qi().expect_one_result(stmt, &mut |stmt| {
                    let id: i64 = stmt.read(0)?;
                    Ok(Self::Output::from_raw_id(id))
                })
            },
        )?
    }

    fn results(self) -> Result<Vec<WithID<Self::Output>>, Error>
    where
        Self: Sized,
        Self::Output: Entity,
    {
        let mut hasher = std::collections::hash_map::DefaultHasher::new();
        self.contribute(&mut hasher);
        self.qi().with_cache(
            hasher.finish(),
            || self.qi().db.conn.prepare(self.derive().assemble()).unwrap(),
            |stmt| {
                self.bind(stmt)?;

                let mut res = Vec::new();
                loop {
                    let state = stmt.next()?;
                    if state == sqlite::State::Done {
                        break;
                    }

                    let id: i64 = stmt.read(0)?;
                    res.push(WithID::wrap(Self::Output::build_from(stmt)?, id));
                }

                Ok(res)
            },
        )?
    }

    fn id_results(self) -> Result<Vec<Self::Output>, Error>
    where
        Self: Sized,
        Self::Output: EntityID,
    {
        let mut hasher = std::collections::hash_map::DefaultHasher::new();
        self.contribute(&mut hasher);
        self.qi().with_cache(
            hasher.finish(),
            || self.qi().db.conn.prepare(self.derive().assemble()).unwrap(),
            |stmt| {
                self.bind(stmt)?;

                let mut res = Vec::new();
                loop {
                    let state = stmt.next()?;
                    if state == sqlite::State::Done {
                        break;
                    }

                    let id: i64 = stmt.read(0)?;
                    res.push(Self::Output::from_raw_id(id));
                }

                Ok(res)
            },
        )?
    }
}