Improve highlights

main.rb

@@ -171,22 +171,21 @@ public
   def examples(word_id)
     word_id = Integer word_id
 
-    @db_conn.exec_params(
+    left_lang_id  = 5 # Georgian
+    right_lang_id = 2 # Russian
+
+    lang_order = left_lang_id < right_lang_id ? 'ASC' : 'DESC'
+
+    result = @db_conn.exec_params(
       (
         <<~SQL
           SELECT
-            array_agg(foo.value ORDER BY foo.language_id DESC)::text[]
-              AS values,
-            array_agg(word_forms.len) AS lens,
-            array_agg(word_form_example_texts.pos) AS positions
+            foo.example_id,
+            array_agg(foo.id    ORDER BY foo.language_id #{lang_order})::text[]
+              AS ids,
+            array_agg(foo.value ORDER BY foo.language_id #{lang_order})::text[]
+              AS values
           FROM example_texts foo
-          LEFT JOIN word_form_example_texts
-          ON word_form_example_texts.example_text_id = foo.id
-          LEFT JOIN word_forms
-          ON
-            word_form_example_texts.word_form_id = word_forms.id
-            AND
-            word_forms.word_id = $1
           INNER JOIN (
             SELECT example_id, language_id, MIN(index) as min_index
             FROM example_texts
@@ -204,7 +203,7 @@ public
                 GROUP BY example_texts.example_id
               )
               AND
-              (language_id = 5 OR language_id = 2)
+              (language_id = $2 OR language_id = $3)
             GROUP BY example_id, language_id
           ) bar
           ON
@@ -214,13 +213,69 @@ public
           GROUP BY foo.example_id
         SQL
       ),
-      [word_id],
+      [word_id, left_lang_id, right_lang_id],
     ).map do |row|
       {
-        values: row['values'].map(&:freeze).freeze,
-        length: row['lens'].compact.first,
-        positions: row['positions'].compact.freeze,
+        example_id: Integer(row['example_id']),
+        left_id: Integer(row['ids'].first),
+        right_id: Integer(row['ids'].last),
+        left: String(row['values'].first).strip.freeze,
+        right: String(row['values'].last).strip.freeze,
+        highlights: [],
       }.freeze
     end.freeze
+
+    highlights =
+      @db_conn.exec_params(
+        (
+          <<~SQL
+            SELECT
+              example_texts.id AS example_text_id,
+              array_agg(
+                word_form_example_texts.pos
+                ORDER BY word_form_example_texts.word_form_id
+              ) AS positions,
+              array_agg(
+                word_forms.len
+                ORDER BY word_forms.id
+              ) AS lengths
+            FROM example_texts
+            INNER JOIN word_form_example_texts
+            ON word_form_example_texts.example_text_id = example_texts.id
+            INNER JOIN word_forms
+            ON word_form_example_texts.word_form_id = word_forms.id
+            WHERE
+              language_id = $1::bigint
+              AND
+              example_texts.example_id = ANY($2::bigint[])
+            GROUP BY example_texts.id
+          SQL
+        ),
+        [
+          left_lang_id,
+          PG::TextEncoder::Array.new.encode(result.map { |h| h[:example_id] }),
+        ],
+      )
+      .map do |row|
+        example_text_id = Integer(row['example_text_id'])
+
+        positions = row['positions'].map { |pos| Integer pos }.freeze
+        lengths   = row['lengths'].map   { |len| Integer len }.freeze
+
+        {
+          example_text_id: example_text_id,
+          data: positions.zip(lengths).map do |pos, len|
+            { pos: pos, len: len }.freeze
+          end.sort_by { |h| h[:pos] }.freeze,
+        }
+      end.to_a
+
+    highlights.each do |highlight|
+      result
+        .find { |item| item[:left_id] == highlight[:example_text_id] }
+        &.tap { |item| item[:highlights].replace highlight[:data] }
+    end
+
+    result.each { |h| h[:highlights].freeze }
   end
 end