use sqlx::any::AnyPoolOptions;
use sqlx::{AnyPool, Row};

#[derive(Clone)]
pub struct Storage {
    pool: AnyPool,
    postgres: bool,
}

impl Storage {
    pub async fn connect(database_url: &str) -> Result<Self, sqlx::Error> {
        sqlx::any::install_default_drivers();
        let postgres =
            database_url.starts_with("postgres://") || database_url.starts_with("postgresql://");
        let pool = AnyPoolOptions::new()
            .max_connections(1)
            .connect(database_url)
            .await?;
        sqlx::query(
            "CREATE TABLE IF NOT EXISTS sim_state (id INTEGER PRIMARY KEY, snapshot TEXT NOT NULL)",
        )
        .execute(&pool)
        .await?;
        Ok(Self { pool, postgres })
    }

    pub async fn load(&self) -> Result<Option<String>, sqlx::Error> {
        let row = sqlx::query("SELECT snapshot FROM sim_state WHERE id = 1")
            .fetch_optional(&self.pool)
            .await?;
        row.map(|row| row.try_get("snapshot")).transpose()
    }

    pub async fn save(&self, snapshot: &str) -> Result<(), sqlx::Error> {
        let query = if self.postgres {
            "INSERT INTO sim_state (id, snapshot) VALUES (1, $1) ON CONFLICT (id) DO UPDATE SET snapshot = excluded.snapshot"
        } else {
            "INSERT INTO sim_state (id, snapshot) VALUES (1, ?) ON CONFLICT (id) DO UPDATE SET snapshot = excluded.snapshot"
        };
        sqlx::query(query)
            .bind(snapshot)
            .execute(&self.pool)
            .await?;
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use super::Storage;

    #[tokio::test]
    async fn sqlite_storage_round_trips_snapshots() {
        let storage = Storage::connect("sqlite::memory:").await.unwrap();
        assert_eq!(storage.load().await.unwrap(), None);

        storage.save("{\"tick\":12}").await.unwrap();
        assert_eq!(
            storage.load().await.unwrap().as_deref(),
            Some("{\"tick\":12}")
        );

        storage.save("{\"tick\":13}").await.unwrap();
        assert_eq!(
            storage.load().await.unwrap().as_deref(),
            Some("{\"tick\":13}")
        );
    }
}