aro-fletch 1.0.0

//! Query and pagination adapters for [`FletchRepository`].
//!
//! Implements the [`Queryable`] and [`Paginatable`] ports from `aro-core`
//! using fletch's dialect-aware [`QueryBuilder`].

use aro_core::error::RepoError;
use aro_core::pagination::{Page, PageRequest};
use aro_core::repository::{BoxFuture, Paginatable, Queryable};
use fletch_orm::Entity as FletchEntityTrait;
use fletch_orm::column::Column;
use fletch_orm::dialect::Dialect;
use fletch_orm::filter::Filter;
use fletch_orm::query_builder::{Order, QueryBuilder};

use crate::error::from_fletch_err;
use crate::repo::{FletchEntity, FletchRepository};

/// Filter and sort criteria for entity queries.
///
/// Build with [`EntityQuery::new`], add [`Filter`] conditions via
/// [`EntityQuery::filter`], and optional [`Order`] clauses via
/// [`EntityQuery::order_by`].
#[derive(Debug, Clone, Default)]
pub struct EntityQuery {
    filters: Vec<Filter>,
    order_by: Vec<(String, Order)>,
}

impl EntityQuery {
    /// Create an empty query (matches all rows).
    pub fn new() -> Self {
        Self::default()
    }

    /// Add a filter condition to the WHERE clause.
    pub fn filter(mut self, filter: Filter) -> Self {
        self.filters.push(filter);
        self
    }

    /// Add an ORDER BY clause.
    pub fn order_by(mut self, column: impl Into<String>, order: Order) -> Self {
        self.order_by.push((column.into(), order));
        self
    }

    fn with_default_order(mut self, column: impl Into<String>, order: Order) -> Self {
        if self.order_by.is_empty() {
            self.order_by.push((column.into(), order));
        }
        self
    }
}

#[derive(Debug, sqlx::FromRow)]
struct CountRow {
    count: i64,
}

fn column_names<E: FletchEntityTrait>() -> Vec<&'static str> {
    E::columns().iter().map(Column::name).collect()
}

fn build_select<E, D>(
    dialect: &D,
    query: &EntityQuery,
    limit: Option<u64>,
    offset: Option<u64>,
) -> fletch_orm::BuiltQuery
where
    E: FletchEntityTrait,
    D: Dialect,
{
    let mut builder = QueryBuilder::select(dialect, E::table_name()).columns(&column_names::<E>());
    for filter in &query.filters {
        builder = builder.filter(filter.clone());
    }
    for (column, order) in &query.order_by {
        builder = builder.order_by(column, *order);
    }
    if let Some(limit) = limit {
        builder = builder.limit(limit);
    }
    if let Some(offset) = offset {
        builder = builder.offset(offset);
    }
    builder.build()
}

fn build_count<E, D>(dialect: &D, query: &EntityQuery) -> fletch_orm::BuiltQuery
where
    E: FletchEntityTrait,
    D: Dialect,
{
    let mut builder = QueryBuilder::select(dialect, E::table_name());
    for filter in &query.filters {
        builder = builder.filter(filter.clone());
    }
    let inner = builder.build();
    let sql = format!(
        "SELECT COUNT(*) AS count FROM ({}) AS _count_sub",
        inner.sql
    );
    fletch_orm::BuiltQuery {
        sql,
        values: inner.values,
    }
}

macro_rules! impl_query {
    ($db:ty, $dialect:expr) => {
        impl<T> FletchRepository<T, $db>
        where
            T: FletchEntity<$db>,
        {
            async fn find_by_query(&self, filter: EntityQuery) -> Result<Vec<T>, RepoError> {
                let built = build_select::<T, _>($dialect, &filter, None, None);
                self.pool()
                    .fetch_all::<T>(&built.sql, &built.values)
                    .await
                    .map_err(from_fletch_err)
            }

            async fn find_page_query(
                &self,
                query: EntityQuery,
                request: PageRequest,
            ) -> Result<Page<T>, RepoError> {
                let entity_query = query.with_default_order(T::id_column(), Order::Asc);
                let count_built = build_count::<T, _>($dialect, &entity_query);
                let count_rows: Vec<CountRow> = self
                    .pool()
                    .fetch_all(&count_built.sql, &count_built.values)
                    .await
                    .map_err(from_fletch_err)?;
                let total = u64::try_from(count_rows.first().map_or(0, |r| r.count)).unwrap_or(0);

                let offset = (request.page.saturating_sub(1)) * request.per_page;
                let select_built = build_select::<T, _>(
                    $dialect,
                    &entity_query,
                    Some(request.per_page),
                    Some(offset),
                );
                let items = self
                    .pool()
                    .fetch_all::<T>(&select_built.sql, &select_built.values)
                    .await
                    .map_err(from_fletch_err)?;

                Ok(Page {
                    items,
                    total,
                    page: request.page,
                    per_page: request.per_page,
                })
            }
        }

        impl<T> Queryable<T> for FletchRepository<T, $db>
        where
            T: FletchEntity<$db>,
        {
            type Filter = EntityQuery;

            fn find_by(&self, filter: EntityQuery) -> BoxFuture<'_, Result<Vec<T>, RepoError>> {
                Box::pin(self.find_by_query(filter))
            }

            fn find_page_by(
                &self,
                filter: EntityQuery,
                request: PageRequest,
            ) -> BoxFuture<'_, Result<Page<T>, RepoError>> {
                Box::pin(self.find_page_query(filter, request))
            }
        }

        impl<T> Paginatable<T> for FletchRepository<T, $db>
        where
            T: FletchEntity<$db>,
        {
            fn find_page(&self, request: PageRequest) -> BoxFuture<'_, Result<Page<T>, RepoError>> {
                Box::pin(self.find_page_query(EntityQuery::new(), request))
            }
        }
    };
}

#[cfg(feature = "sqlite")]
impl_query!(sqlx::Sqlite, &fletch_orm::SqliteDialect);

#[cfg(feature = "postgres")]
impl_query!(sqlx::Postgres, &fletch_orm::PostgresDialect);

#[cfg(feature = "mysql")]
impl_query!(sqlx::MySql, &fletch_orm::MySqlDialect);