From 7eb2639a5bd9ea63e9c4da87f8d1c93831723109 Mon Sep 17 00:00:00 2001
From: Stefan Garlonta <stefan.garlonta@gmail.com>
Date: Thu, 28 Sep 2023 15:56:04 +0200
Subject: [PATCH] :sparkles: Implement JSON loader

---
 pystreamapi/loaders/__json/__init__.py      |  0
 pystreamapi/loaders/__json/__json_loader.py | 46 ++++++++++++++
 tests/test_json_loader.py                   | 68 +++++++++++++++++++++
 3 files changed, 114 insertions(+)
 create mode 100644 pystreamapi/loaders/__json/__init__.py
 create mode 100644 pystreamapi/loaders/__json/__json_loader.py
 create mode 100644 tests/test_json_loader.py

diff --git a/pystreamapi/loaders/__json/__init__.py b/pystreamapi/loaders/__json/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/pystreamapi/loaders/__json/__json_loader.py b/pystreamapi/loaders/__json/__json_loader.py
new file mode 100644
index 0000000..cf416ef
--- /dev/null
+++ b/pystreamapi/loaders/__json/__json_loader.py
@@ -0,0 +1,46 @@
+import json as jsonlib
+from collections import namedtuple
+
+from pystreamapi.loaders.__lazy_file_iterable import LazyFileIterable
+from pystreamapi.loaders.__loader_utils import LoaderUtils
+
+
+def json(src: str, read_from_src=False) -> LazyFileIterable:
+    """
+    Loads JSON data from either a path or a string and converts it into a list of namedtuples.
+
+    Returns:
+        list: A list of namedtuples, where each namedtuple represents an object in the JSON.
+        :param src: Either the path to a JSON file or a JSON string.
+        :param read_from_src: If True, src is treated as a JSON string. If False, src is treated as
+        a path to a JSON file.
+    """
+    if read_from_src:
+        return LazyFileIterable(lambda: __load_json_string(src))
+    path = LoaderUtils.validate_path(src)
+    return LazyFileIterable(lambda: __load_json_file(path))
+
+
+def __load_json_file(file_path):
+    """Load a JSON file and convert it into a list of namedtuples"""
+    # skipcq: PTC-W6004
+    with open(file_path, mode='r', encoding='utf-8') as jsonfile:
+        src = jsonfile.read()
+        if src == '':
+            return []
+        data = jsonlib.loads(src, object_hook=__dict_to_namedtuple)
+    return data
+
+
+def __load_json_string(json_string):
+    """Load JSON data from a string and convert it into a list of namedtuples"""
+    return jsonlib.loads(json_string, object_hook=__dict_to_namedtuple)
+
+
+def __dict_to_namedtuple(d, name='Item'):
+    """Convert a dictionary to a namedtuple"""
+    if isinstance(d, dict):
+        fields = list(d.keys())
+        Item = namedtuple(name, fields)
+        return Item(**{k: __dict_to_namedtuple(v, k) for k, v in d.items()})
+    return d
diff --git a/tests/test_json_loader.py b/tests/test_json_loader.py
new file mode 100644
index 0000000..ba7ed3d
--- /dev/null
+++ b/tests/test_json_loader.py
@@ -0,0 +1,68 @@
+from unittest import TestCase
+from unittest.mock import patch, mock_open
+
+from pystreamapi.loaders import json
+
+file_content = """
+[
+    {
+        "attr1": 1,
+        "attr2": 2.0
+    },
+    {
+        "attr1": "a",
+        "attr2": "b"
+    }
+]
+"""
+
+
+class TestJsonLoader(TestCase):
+
+    def test_json_loader_from_file(self):
+        with (patch('builtins.open', mock_open(read_data=file_content)),
+              patch('os.path.exists', return_value=True),
+              patch('os.path.isfile', return_value=True)):
+            data = json('path/to/data.json')
+            self.assertEqual(len(data), 2)
+            self.assertEqual(data[0].attr1, 1)
+            self.assertIsInstance(data[0].attr1, int)
+            self.assertEqual(data[0].attr2, 2.0)
+            self.assertIsInstance(data[0].attr2, float)
+            self.assertEqual(data[1].attr1, 'a')
+            self.assertIsInstance(data[1].attr1, str)
+
+    def test_json_loader_is_iterable(self):
+        with (patch('builtins.open', mock_open(read_data=file_content)),
+              patch('os.path.exists', return_value=True),
+              patch('os.path.isfile', return_value=True)):
+            data = json('path/to/data.json')
+            self.assertEqual(len(list(iter(data))), 2)
+
+    def test_json_loader_with_empty_file(self):
+        with (patch('builtins.open', mock_open(read_data="")),
+              patch('os.path.exists', return_value=True),
+              patch('os.path.isfile', return_value=True)):
+            data = json('path/to/data.json')
+            self.assertEqual(len(data), 0)
+
+    def test_json_loader_with_invalid_path(self):
+        with self.assertRaises(FileNotFoundError):
+            json('path/to/invalid.json')
+
+    def test_json_loader_with_no_file(self):
+        with self.assertRaises(ValueError):
+            json('./')
+
+    def test_json_loader_from_string(self):
+        data = json(file_content, read_from_src=True)
+        self.assertEqual(len(data), 2)
+        self.assertEqual(data[0].attr1, 1)
+        self.assertIsInstance(data[0].attr1, int)
+        self.assertEqual(data[0].attr2, 2.0)
+        self.assertIsInstance(data[0].attr2, float)
+        self.assertEqual(data[1].attr1, 'a')
+        self.assertIsInstance(data[1].attr1, str)
+
+    def test_json_loader_from_empty_string(self):
+        json('', read_from_src=True)