From c695a1ffd2306e663cf027d1727dca4e8c0c1503 Mon Sep 17 00:00:00 2001
From: Tamo <tamo@meilisearch.com>
Date: Mon, 13 Sep 2021 14:27:14 +0200
Subject: [PATCH] add the possibility to sort by descending order on geoPoint

---
 milli/src/search/criteria/geo.rs | 39 ++++++++++++++++++++++++++++----
 milli/src/search/criteria/mod.rs | 15 ++++++------
 2 files changed, 42 insertions(+), 12 deletions(-)

diff --git a/milli/src/search/criteria/geo.rs b/milli/src/search/criteria/geo.rs
index 9629a4a15..de6de8912 100644
--- a/milli/src/search/criteria/geo.rs
+++ b/milli/src/search/criteria/geo.rs
@@ -10,6 +10,7 @@ use crate::{GeoPoint, Index, Result};
 pub struct Geo<'t> {
     index: &'t Index,
     rtxn: &'t heed::RoTxn<'t>,
+    ascending: bool,
     parent: Box<dyn Criterion + 't>,
     candidates: Box<dyn Iterator<Item = RoaringBitmap>>,
     allowed_candidates: RoaringBitmap,
@@ -19,11 +20,30 @@ pub struct Geo<'t> {
 }
 
 impl<'t> Geo<'t> {
-    pub fn new(
+    pub fn asc(
         index: &'t Index,
         rtxn: &'t heed::RoTxn<'t>,
         parent: Box<dyn Criterion + 't>,
         point: [f64; 2],
+    ) -> Result<Self> {
+        Self::new(index, rtxn, parent, point, true)
+    }
+
+    pub fn desc(
+        index: &'t Index,
+        rtxn: &'t heed::RoTxn<'t>,
+        parent: Box<dyn Criterion + 't>,
+        point: [f64; 2],
+    ) -> Result<Self> {
+        Self::new(index, rtxn, parent, point, false)
+    }
+
+    fn new(
+        index: &'t Index,
+        rtxn: &'t heed::RoTxn<'t>,
+        parent: Box<dyn Criterion + 't>,
+        point: [f64; 2],
+        ascending: bool,
     ) -> Result<Self> {
         let candidates = Box::new(iter::empty());
         let allowed_candidates = index.geo_faceted_documents_ids(rtxn)?;
@@ -33,6 +53,7 @@ impl<'t> Geo<'t> {
         Ok(Self {
             index,
             rtxn,
+            ascending,
             parent,
             candidates,
             allowed_candidates,
@@ -89,9 +110,12 @@ impl Criterion for Geo<'_> {
                         }
                         self.allowed_candidates = &candidates - params.excluded_candidates;
                         self.candidates = match rtree {
-                            Some(rtree) => {
-                                geo_point(rtree, self.allowed_candidates.clone(), self.point)
-                            }
+                            Some(rtree) => geo_point(
+                                rtree,
+                                self.allowed_candidates.clone(),
+                                self.point,
+                                self.ascending,
+                            ),
                             None => Box::new(std::iter::empty()),
                         };
                     }
@@ -106,6 +130,7 @@ fn geo_point(
     rtree: &RTree<GeoPoint>,
     mut candidates: RoaringBitmap,
     point: [f64; 2],
+    ascending: bool,
 ) -> Box<dyn Iterator<Item = RoaringBitmap>> {
     let mut results = Vec::new();
     for point in rtree.nearest_neighbor_iter(&point) {
@@ -117,5 +142,9 @@ fn geo_point(
         }
     }
 
-    Box::new(results.into_iter())
+    if ascending {
+        Box::new(results.into_iter())
+    } else {
+        Box::new(results.into_iter().rev())
+    }
 }
diff --git a/milli/src/search/criteria/mod.rs b/milli/src/search/criteria/mod.rs
index 3c9485012..c2de55de5 100644
--- a/milli/src/search/criteria/mod.rs
+++ b/milli/src/search/criteria/mod.rs
@@ -15,7 +15,7 @@ use super::query_tree::{Operation, PrimitiveQueryPart, Query, QueryKind};
 use crate::criterion::{AscDesc as AscDescName, Member};
 use crate::search::criteria::geo::Geo;
 use crate::search::{word_derivations, WordDerivationsCache};
-use crate::{DocumentId, FieldId, Index, Result, TreeLevel, UserError};
+use crate::{DocumentId, FieldId, Index, Result, TreeLevel};
 
 mod asc_desc;
 mod attribute;
@@ -304,17 +304,18 @@ impl<'t> CriteriaBuilder<'t> {
                                     criterion,
                                     field.to_string(),
                                 )?),
-                                AscDescName::Asc(Member::Geo(point)) => Box::new(Geo::new(
+                                AscDescName::Asc(Member::Geo(point)) => Box::new(Geo::asc(
+                                    &self.index,
+                                    &self.rtxn,
+                                    criterion,
+                                    point.clone(),
+                                )?),
+                                AscDescName::Desc(Member::Geo(point)) => Box::new(Geo::desc(
                                     &self.index,
                                     &self.rtxn,
                                     criterion,
                                     point.clone(),
                                 )?),
-                                AscDescName::Desc(Member::Geo(_point)) => {
-                                    return Err(UserError::InvalidSortName {
-                                        name: "sorting in descending order is not supported for the geosearch".to_string(),
-                                    })?
-                                }
                             };
                         }
                         criterion