Added downloading packages from remote index

- #7
- LibreTranslate/LibreTranslate#30

argostranslate/package.py

@@ -3,19 +3,39 @@
 import json
 import shutil
 
+import requests
+
 from argostranslate import settings
 
-class Package:
-    """An installed package.
+"""
+## `package` module example usage
+```
+from argostranslate import package
+
+# Update package definitions from remote
+package.update_package_index()
+
+# Load available packages from local package index
+available_packages = package.load_available_packages()
+
+# Download and install all available packages
+for available_package in available_packages:
+    download_path = available_package.download()
+    package.install_from_path(download_path)
+"""
+
+class IPackage:
+    """A package, can be either installed locally or available from a remote package index.
 
     Attributes:
-        package_path (Path): The path to the installed package.
+        package_path (Path): The path to the installed package. None if not installed.
         package_version (str): The version of the package.
         argos_version (str): The version of Argos Translate the package is intended for.
         from_code (str): The code of the language the package translates from.
         from_name (str): Human readable name of the language the package translates from.
         to_code (str): The code of the language the package translates to.
         to_name (str): Human readable name of the language the package translates to.
+        links [list(str)]: A list of links to download the package
 
     Packages are a zip archive of a directory with metadata.json
     in its root the .argosmodel file extension. By default a 
@@ -34,31 +54,26 @@ class Package:
         "from_code": "en",
         "from_name": "English",
         "to_code": "es",
-        "to_name": "Spanish"
+        "to_name": "Spanish",
+        "links": ["https://example.com/en_es.argosmodel"]
     }
 
     """
 
-    def __init__(self, package_path):
-        """Create a new Package.
+    def load_metadata_from_json(self, metadata):
+        """Loads package metadata from a JSON object.
 
         Args:
-            package_path (str): Path to installed package directory.
+            metadata: A json object from json.load
 
         """
-        self.package_path = package_path
-        metadata_path = package_path / 'metadata.json'
-        if not metadata_path.exists():
-            raise Exception('Error opening package at ' +
-                    str(metadata_path) + ' no metadata.json')
-        with open(metadata_path) as metadata_file:
-            metadata = json.load(metadata_file)
-            self.package_version = metadata.get('package_version')
-            self.argos_version = metadata.get('argos_version')
-            self.from_code = metadata.get('from_code')
-            self.from_name = metadata.get('from_name')
-            self.to_code = metadata.get('to_code')
-            self.to_name = metadata.get('to_name')
+        self.package_version = metadata.get('package_version')
+        self.argos_version = metadata.get('argos_version')
+        self.from_code = metadata.get('from_code')
+        self.from_name = metadata.get('from_name')
+        self.to_code = metadata.get('to_code')
+        self.to_name = metadata.get('to_name')
+        self.links = metadata.get('links')
 
     def get_readme(self):
         """Returns the text of the README.md in this package.
@@ -78,6 +93,40 @@ def get_readme(self):
     def __str__(self):
         return "{} -> {}".format(self.from_name, self.to_name)
 
+class Package(IPackage):
+    """An installed package"""
+    def __init__(self, package_path):
+        """Create a new Package from path.
+
+        Args:
+            package_path (str): Path to installed package directory.
+
+        """
+        self.package_path = package_path
+        metadata_path = package_path / 'metadata.json'
+        if not metadata_path.exists():
+            raise Exception('Error opening package at ' +
+                    str(metadata_path) + ' no metadata.json')
+        with open(metadata_path) as metadata_file:
+            metadata = json.load(metadata_file)
+            self.load_metadata_from_json(metadata)
+
+class AvailablePackage(IPackage):
+    """A package available for download"""
+    def __init__(self, metadata):
+        """Creates a new AvailablePackage from a metadata object"""
+        self.load_metadata_from_json(metadata)
+
+    def download(self):
+        """Downloads the AvailablePackage and returns its path"""
+        url = self.links[0]
+        filename = self.from_code + '_' + self.to_code + '.argosmodel'
+        filepath = settings.downloads_dir / filename
+        r = requests.get(url, allow_redirects=True)
+        open(filepath, 'wb').write(r.content)
+        return filepath
+
+
 def install_from_path(path):
     """Install a package (zip archive ending in .argosmodel).
 
@@ -120,3 +169,22 @@ def get_installed_packages(path=None):
                 to_return.append(Package(path))
     return to_return
 
+def update_package_index():
+    """Downloads remote package index"""
+    r = requests.get(settings.remote_package_index, allow_redirects=True)
+    open(settings.local_package_index, 'wb').write(r.content)
+
+def load_available_packages():
+    """Returns a list of AvailablePackages from the package index."""
+    try:
+        with open(settings.local_package_index) as index_file:
+            index = json.load(index_file)
+            to_return = []
+            for metadata in index:
+                package = AvailablePackage(metadata)
+                to_return.append(package)
+            return to_return
+    except FileNotFoundError:
+        raise Exception('Local package index not found,' +
+                ' use package.update_package_index() to load it')
+

argostranslate/settings.py

@@ -19,6 +19,9 @@
         default=home_dir / '.local' / 'cache')) / 'argos-translate'
 os.makedirs(cache_dir, exist_ok=True)
 
+downloads_dir = cache_dir / 'downloads'
+os.makedirs(downloads_dir, exist_ok=True)
+
 # Legacy support to upgrade from argostranslate<1.1.0
 legacy_package_data_dirs = [Path.home() / '.argos-translate' / 'packages']
 if 'SNAP' in os.environ:
@@ -49,6 +52,10 @@
     package_dirs.append(Path(os.environ[
             'ARGOS_TRANSLATE_PACKAGE_DIR']))
 
+remote_package_index = 'https://raw.githubusercontent.com/argosopentech/argospm-index/main/index.json'
+
+local_package_index = cache_dir / 'index.json'
+
 about_text = """
 Argos Translate is an open source neural machine
 translation application created by Argos Open

requirements.txt

@@ -2,5 +2,6 @@ ctranslate2==1.17.1
 sentencepiece==0.1.91
 stanza==1.1.1
 PyQt5==5.15.1
+requests==2.25.1
 sphinx==3.2.1
 sphinx-rtd-theme==0.5.0