server/posts: change reverse image search API

Add exact duplicates search; refactor to use classes over dictionaries

API.md

@@ -1070,17 +1070,15 @@ data.
 
 - **Output**
 
-    A list of [image search results](#image-search-result).
+    An [image search result](#image-search-result).
 
 - **Errors**
 
-    - input file is not an image
     - privileges are too low
 
 - **Description**
 
-    Retrieves posts that look like the input image. Works only on images and
-    animations, i.e. does not work for videos and Flash movies.
+    Retrieves posts that look like the input image.
 
 ## Listing comments
 - **Request**
@@ -2152,14 +2150,15 @@ A result of reverse image search operation.
 
 ```json5
 {
-    "results": [
+    "exactPost": <exact-post>,
+    "similarPosts": [
         {
-            "dist": <distance>,
-            "post": <post>
+            "distance": <distance>,
+            "post": <similar-post>
         },
         {
-            "dist": <distance>,
-            "post": <post>
+            "distance": <distance>,
+            "post": <similar-post>
         },
         ...
     ]
@@ -2167,9 +2166,14 @@ A result of reverse image search operation.
 ```
 
 **Field meaning**
-- `<dist>`: distance from the original image (0..1). The lower this value is, the more similar the
-post is.
-- `<post>`: a [post resource](#post).
+-  `exact-post`: a [post resource](#post) that is exact byte-to-byte duplicate
+   of the input file. May be `null`.
+- `<similar-post>`: a [post resource](#post) that isn't exact duplicate, but
+   visually resembles the input file. Works only on images and animations, i.e.
+   does not work for videos and Flash movies. For non-images and corrupted
+   images, this list is empty.
+- `<distance>`: distance from the original image (0..1). The lower this value
+   is, the more similar the post is.
 
 # Search
 

server/.pylintrc

@@ -15,6 +15,7 @@ reports=no
 disable=
     # we're not java
     missing-docstring,
+    broad-except,
 
     # covered better by pycodestyle
     bad-continuation,

server/szurubooru/api/post_api.py

@@ -212,11 +212,14 @@ def get_posts_by_image(ctx, _params=None):
     auth.verify_privilege(ctx.user, 'posts:reverse_search')
     content = ctx.get_file('content', required=True)
     return {
-        'results': [
-            {
-                'dist': item['dist'],
-                'post': _serialize_post(ctx, item['post']),
-            }
-            for item in posts.search_by_image(content)
-        ],
+        'exactPost':
+            _serialize_post(ctx, posts.search_by_image_exact(content)),
+        'similarPosts':
+            [
+                {
+                    'distance': lookalike.distance,
+                    'post': _serialize_post(ctx, lookalike.post),
+                }
+                for lookalike in posts.search_by_image(content)
+            ],
     }

server/szurubooru/func/image_hash.py

@@ -1,7 +1,7 @@
 import elasticsearch
 import elasticsearch_dsl
 from image_match.elasticsearch_driver import SignatureES
-from szurubooru import config, errors
+from szurubooru import config
 
 
 # pylint: disable=invalid-name
@@ -12,6 +12,13 @@ es = elasticsearch.Elasticsearch([{
 session = SignatureES(es, index='szurubooru')
 
 
+class Lookalike:
+    def __init__(self, score, distance, path):
+        self.score = score
+        self.distance = distance
+        self.path = path
+
+
 def add_image(path, image_content):
     if not path or not image_content:
         return
@@ -35,15 +42,14 @@ def search_by_image(image_content):
         for result in session.search_image(
                 path=image_content,  # sic
                 bytestream=True):
-            yield {
-                'score': result['score'],
-                'dist': result['dist'],
-                'path': result['path'],
-            }
+            yield Lookalike(
+                score=result['score'],
+                distance=result['dist'],
+                path=result['path'])
     except elasticsearch.exceptions.ElasticsearchException:
         raise
     except Exception:
-        raise errors.SearchError('Error searching (invalid input?)')
+        yield from []
 
 
 def purge():

server/szurubooru/func/posts.py

@@ -57,6 +57,12 @@ class InvalidPostFlagError(errors.ValidationError):
     pass
 
 
+class PostLookalike(image_hash.Lookalike):
+    def __init__(self, score, distance, post):
+        super().__init__(score, distance, post.post_id)
+        self.post = post
+
+
 SAFETY_MAP = {
     db.Post.SAFETY_SAFE: 'safe',
     db.Post.SAFETY_SKETCHY: 'sketchy',
@@ -534,13 +540,20 @@ def merge_posts(source_post, target_post, replace_content):
         update_post_content(target_post, content)
 
 
+def search_by_image_exact(image_content):
+    checksum = util.get_sha1(image_content)
+    return db.session \
+        .query(db.Post) \
+        .filter(db.Post.checksum == checksum) \
+        .one_or_none()
+
+
 def search_by_image(image_content):
     for result in image_hash.search_by_image(image_content):
-        yield {
-            'score': result['score'],
-            'dist': result['dist'],
-            'post': get_post_by_id(result['path'])
-        }
+        yield PostLookalike(
+            score=result.score,
+            distance=result.distance,
+            post=get_post_by_id(result.path))
 
 
 def populate_reverse_search():