use chrono::TimeDelta;
use sqlx::sqlite::SqlitePool;

use super::{Id, Invite, Summary, repo::Provider as _};
use crate::{
    clock::DateTime,
    db::{Duplicate as _, NotFound as _},
    event::Broadcaster,
    name::Name,
    token::{Secret, repo::Provider as _},
    user::{
        Password, User,
        create::{self, Create},
    },
};

pub struct Invites<'a> {
    db: &'a SqlitePool,
    events: &'a Broadcaster,
}

impl<'a> Invites<'a> {
    pub const fn new(db: &'a SqlitePool, events: &'a Broadcaster) -> Self {
        Self { db, events }
    }

    pub async fn issue(&self, issuer: &User, issued_at: &DateTime) -> Result<Invite, sqlx::Error> {
        let mut tx = self.db.begin().await?;
        let invite = tx.invites().create(issuer, issued_at).await?;
        tx.commit().await?;

        Ok(invite)
    }

    pub async fn get(&self, invite: &Id) -> Result<Option<Summary>, sqlx::Error> {
        let mut tx = self.db.begin().await?;
        let invite = tx.invites().summary(invite).await.optional()?;
        tx.commit().await?;

        Ok(invite)
    }

    pub async fn accept(
        &self,
        invite: &Id,
        name: &Name,
        password: &Password,
        accepted_at: &DateTime,
    ) -> Result<(User, Secret), AcceptError> {
        let create = Create::begin(name, password, accepted_at);

        let mut tx = self.db.begin().await?;
        let invite = tx
            .invites()
            .by_id(invite)
            .await
            .not_found(|| AcceptError::NotFound(invite.clone()))?;
        // Split the tx here so we don't block writes while we deal with the password,
        // and don't deal with the password until we're fairly confident we can accept
        // the invite. Final validation is in the next tx.
        tx.commit().await?;

        let validated = create.validate()?;

        let mut tx = self.db.begin().await?;
        // If the invite has been deleted or accepted in the interim, this step will
        // catch it.
        tx.invites().accept(&invite).await?;
        let stored = validated
            .store(&mut tx)
            .await
            .duplicate(|| AcceptError::DuplicateLogin(name.clone()))?;
        let secret = tx.tokens().issue(stored.user(), accepted_at).await?;
        tx.commit().await?;

        let login = stored.publish(self.events);

        Ok((login.as_created(), secret))
    }

    pub async fn expire(&self, relative_to: &DateTime) -> Result<(), sqlx::Error> {
        // Somewhat arbitrarily, expire after one day.
        let expire_at = relative_to.to_owned() - TimeDelta::days(1);

        let mut tx = self.db.begin().await?;
        tx.invites().expire(&expire_at).await?;
        tx.commit().await?;

        Ok(())
    }
}

#[derive(Debug, thiserror::Error)]
pub enum AcceptError {
    #[error("invite not found: {0}")]
    NotFound(Id),
    #[error("invalid user name: {0}")]
    InvalidName(Name),
    #[error("name in use: {0}")]
    DuplicateLogin(Name),
    #[error(transparent)]
    Database(#[from] sqlx::Error),
    #[error(transparent)]
    PasswordHash(#[from] password_hash::Error),
}

impl From<create::Error> for AcceptError {
    fn from(error: create::Error) -> Self {
        match error {
            create::Error::InvalidName(name) => Self::InvalidName(name),
            create::Error::PasswordHash(error) => Self::PasswordHash(error),
        }
    }
}