server: implement median of post metrics

3 files changed, 82 insertions, 2 deletions

diff --git a/server/szurubooru/api/metric_api.py b/server/szurubooru/api/metric_api.py
index 15f48d7..2b87a5d 100644
--- a/server/szurubooru/api/metric_api.py
+++ b/server/szurubooru/api/metric_api.py
@@ -1,3 +1,4 @@
+from math import ceil
 from typing import Optional, List, Dict
 from szurubooru import db, model, search, rest
 from szurubooru.func import (
@@ -23,7 +24,7 @@ def _serialize_post_metric(
     )
 
 
-def _get_metric(params: Dict[str, str]) -> model.Tag:
+def _get_metric(params: Dict[str, str]) -> model.Metric:
     return metrics.get_metric_by_tag_name(params['tag_name'])
 
 
@@ -68,6 +69,21 @@ def delete_metric(ctx: rest.Context, params: Dict[str, str]) -> rest.Response:
 def get_post_metrics(
         ctx: rest.Context, params: Dict[str, str] = {}) -> rest.Response:
     auth.verify_privilege(ctx.user, 'metrics:list')
-    _search_executor_config.user = ctx.user
     return _search_executor.execute_and_serialize(
         ctx, lambda post_metric: _serialize_post_metric(ctx, post_metric))
+
+
+@rest.routes.get('/post-metrics/median/(?P<tag_name>.+)')
+def get_post_metrics_median(
+        ctx: rest.Context, params: Dict[str, str] = {}) -> rest.Response:
+    auth.verify_privilege(ctx.user, 'metrics:list')
+    metric = _get_metric(params)
+    tag_name = params['tag_name']
+    query_text = ctx.get_param_as_string(
+        'query',
+        default='%s:%f..%f' % (tag_name, metric.min, metric.max))
+    count = _search_executor.count(query_text)
+    _, results = _search_executor.execute(query_text, ceil(count/2) - 1, 1)
+    return {
+        'results': list([_serialize_post_metric(ctx, pm) for pm in results])
+    }
diff --git a/server/szurubooru/search/executor.py b/server/szurubooru/search/executor.py
index ca55c6d..3a8ec68 100644
--- a/server/szurubooru/search/executor.py
+++ b/server/szurubooru/search/executor.py
@@ -140,6 +140,20 @@ class Executor:
             'results': list([serializer(entity) for entity in entities]),
         }
 
+    def count(self, query_text:str) -> int:
+        search_query = self.parser.parse(query_text)
+        self.config.on_search_query_parsed(search_query)
+        count_query = self.config.create_count_query(True)
+        count_query = count_query.options(sa.orm.lazyload('*'))
+        count_query = self._prepare_db_query(count_query, search_query, False)
+        count_statement = (
+            count_query
+            .statement
+            .with_only_columns([sa.func.count()])
+            .order_by(None))
+        count = db.session.execute(count_statement).scalar()
+        return count
+
     def _prepare_db_query(
             self,
             db_query: SaQuery,
diff --git a/server/szurubooru/tests/api/test_metric_retrieving.py b/server/szurubooru/tests/api/test_metric_retrieving.py
new file mode 100644
index 0000000..901786d
--- /dev/null
+++ b/server/szurubooru/tests/api/test_metric_retrieving.py
@@ -0,0 +1,50 @@
+import pytest
+from szurubooru import api, db, model
+
+
+@pytest.mark.parametrize('query,expected_value', [
+    ('', 5),
+    ('mytag:0..', 5),
+    ('mytag:..10', 5),
+    ('mytag:0..10', 5),
+    ('mytag:2..8', 5),
+    ('mytag:0..8', 4),
+    ('mytag:0..6', 4),
+    ('mytag:0..5.5', 4),
+    ('mytag:0..4', 1),
+    ('mytag:1..4', 1),
+    ('mytag:2..3', None),
+])
+def test_median(
+        query,
+        expected_value,
+        tag_factory,
+        post_factory,
+        metric_factory,
+        post_metric_factory,
+        context_factory,
+        user_factory):
+    tag = tag_factory(names=['mytag'])
+    post1 = post_factory(tags=[tag])
+    post4 = post_factory(tags=[tag])
+    post5 = post_factory(tags=[tag])
+    post6 = post_factory(tags=[tag])
+    post10 = post_factory(tags=[tag])
+    metric = metric_factory(tag=tag, min=0, max=10)
+    pm1 = post_metric_factory(metric=metric, post=post1, value=1)
+    pm4 = post_metric_factory(metric=metric, post=post4, value=4)
+    pm5 = post_metric_factory(metric=metric, post=post5, value=5)
+    pm6 = post_metric_factory(metric=metric, post=post6, value=6)
+    pm10 = post_metric_factory(metric=metric, post=post10, value=10)
+    db.session.add_all([tag, metric, pm1, pm4, pm5, pm6, pm10,
+                        post1, post4, post5, post6, post10])
+    db.session.flush()
+    response = api.metric_api.get_post_metrics_median(
+        context_factory(
+            params={'query': query},
+            user=user_factory(rank=model.User.RANK_REGULAR)),
+        {'tag_name': 'mytag'})
+    if not expected_value:
+        assert len(response['results']) == 0
+    else:
+        assert response['results'][0]['value'] == expected_value