use sqlx::{sqlite::Sqlite, SqliteConnection, Transaction};

use crate::{
    channel::{Channel, History, Id},
    clock::DateTime,
    event::{Instant, ResumePoint, Sequence},
};

pub trait Provider {
    fn channels(&mut self) -> Channels;
}

impl<'c> Provider for Transaction<'c, Sqlite> {
    fn channels(&mut self) -> Channels {
        Channels(self)
    }
}

pub struct Channels<'t>(&'t mut SqliteConnection);

impl<'c> Channels<'c> {
    pub async fn create(&mut self, name: &str, created: &Instant) -> Result<History, sqlx::Error> {
        let id = Id::generate();
        let channel = sqlx::query!(
            r#"
                insert
                into channel (id, name, created_at, created_sequence)
                values ($1, $2, $3, $4)
                returning
                    id as "id: Id",
                    name,
                    created_at as "created_at: DateTime",
                    created_sequence as "created_sequence: Sequence"
            "#,
            id,
            name,
            created.at,
            created.sequence,
        )
        .map(|row| History {
            channel: Channel {
                id: row.id,
                name: row.name,
            },
            created: Instant {
                at: row.created_at,
                sequence: row.created_sequence,
            },
            deleted: None,
        })
        .fetch_one(&mut *self.0)
        .await?;

        Ok(channel)
    }

    pub async fn by_id(&mut self, channel: &Id) -> Result<History, sqlx::Error> {
        let channel = sqlx::query!(
            r#"
                select
                    id as "id: Id",
                    name,
                    created_at as "created_at: DateTime",
                    created_sequence as "created_sequence: Sequence"
                from channel
                where id = $1
            "#,
            channel,
        )
        .map(|row| History {
            channel: Channel {
                id: row.id,
                name: row.name,
            },
            created: Instant {
                at: row.created_at,
                sequence: row.created_sequence,
            },
            deleted: None,
        })
        .fetch_one(&mut *self.0)
        .await?;

        Ok(channel)
    }

    pub async fn all(&mut self, resume_at: ResumePoint) -> Result<Vec<History>, sqlx::Error> {
        let channels = sqlx::query!(
            r#"
                select
                    id as "id: Id",
                    name,
                    created_at as "created_at: DateTime",
                    created_sequence as "created_sequence: Sequence"
                from channel
                where coalesce(created_sequence <= $1, true)
                order by channel.name
            "#,
            resume_at,
        )
        .map(|row| History {
            channel: Channel {
                id: row.id,
                name: row.name,
            },
            created: Instant {
                at: row.created_at,
                sequence: row.created_sequence,
            },
            deleted: None,
        })
        .fetch_all(&mut *self.0)
        .await?;

        Ok(channels)
    }

    pub async fn replay(
        &mut self,
        resume_at: Option<Sequence>,
    ) -> Result<Vec<History>, sqlx::Error> {
        let channels = sqlx::query!(
            r#"
                select
                    id as "id: Id",
                    name,
                    created_at as "created_at: DateTime",
                    created_sequence as "created_sequence: Sequence"
                from channel
                where coalesce(created_sequence > $1, true)
            "#,
            resume_at,
        )
        .map(|row| History {
            channel: Channel {
                id: row.id,
                name: row.name,
            },
            created: Instant {
                at: row.created_at,
                sequence: row.created_sequence,
            },
            deleted: None,
        })
        .fetch_all(&mut *self.0)
        .await?;

        Ok(channels)
    }

    pub async fn delete(
        &mut self,
        channel: &Id,
        deleted: &Instant,
    ) -> Result<History, sqlx::Error> {
        let channel = sqlx::query!(
            r#"
                delete from channel
                where id = $1
                returning
                    id as "id: Id",
                    name,
                    created_at as "created_at: DateTime",
                    created_sequence as "created_sequence: Sequence"
            "#,
            channel,
        )
        .map(|row| History {
            channel: Channel {
                id: row.id,
                name: row.name,
            },
            created: Instant {
                at: row.created_at,
                sequence: row.created_sequence,
            },
            deleted: Some(*deleted),
        })
        .fetch_one(&mut *self.0)
        .await?;

        Ok(channel)
    }

    pub async fn expired(&mut self, expired_at: &DateTime) -> Result<Vec<Id>, sqlx::Error> {
        let channels = sqlx::query_scalar!(
            r#"
                select
                    channel.id as "id: Id"
                from channel
                    left join message
                where created_at < $1
                    and message.id is null
            "#,
            expired_at,
        )
        .fetch_all(&mut *self.0)
        .await?;

        Ok(channels)
    }
}