From cb67c624e54fadc4b47fdfa71f03c3b0fae640c3 Mon Sep 17 00:00:00 2001
From: Frederik Rietdijk <fridh@fridh.nl>
Date: Thu, 21 Nov 2019 10:48:43 +0100
Subject: [PATCH] simplify fetchPypi, remove need for overrides

We already have the name of the file that we need, so let's fetch it
directly instead of breaking it apart first, passing it to the Nixpkgs
fetchPypi, which would then put it together again.
---
 default.nix   | 35 ++++++++++++++++++--------------
 overrides.nix | 56 ++-------------------------------------------------
 2 files changed, 22 insertions(+), 69 deletions(-)

diff --git a/default.nix b/default.nix
index 3150e30..9ac920e 100644
--- a/default.nix
+++ b/default.nix
@@ -14,6 +14,18 @@ let
     else default
   );
 
+  # Fetch the artifacts from the PyPI index.
+  #
+  # Args:
+  #   file: filename including extension
+  #   hash: SRI hash
+  #   kind: Language implementation and version tag https://www.python.org/dev/peps/pep-0427/#file-name-convention
+  fetchPypi = lib.makeOverridable ({ pname, file, hash, kind }:
+    pkgs.fetchurl {
+      url = "https://files.pythonhosted.org/packages/${kind}/${builtins.substring 0 1 file}/${pname}/${file}";
+      inherit hash;
+    });
+
   getAttrPath = attrPath: set: (
     builtins.foldl'
     (acc: v: if builtins.typeOf acc == "set" && builtins.hasAttr v acc then acc."${v}" else null)
@@ -126,21 +138,14 @@ let
             broken = ! isCompatible python.version pkgMeta.python-versions;
           };
 
-          src =
-            if format == "wheel"
-            then self.fetchPypi {
-              pname = pkgMeta.name;
-              version = pkgMeta.version;
-              sha256 = file.hash;
-              format = "wheel";
-            }
-            else self.fetchPypi {
-              pname = pkgMeta.name;
-              version = pkgMeta.version;
-              sha256 = file.hash;
-              extension = getExtension file.file;
-            };
-
+          src = fetchPypi {
+            pname = pkgMeta.name;
+            inherit (file) file hash;
+            # We need to retrieve kind from the interpreter and the filename of the package
+            # Interpreters should declare what wheel types they're compatible with (python type + ABI)
+            # Here we can then choose a file based on that info.
+            kind = if format == "wheel" then "py2.py3" else "source";
+          };
         };
 
         # Filter packages by their PEP508 markers
diff --git a/overrides.nix b/overrides.nix
index 2f4ca63..b92c1e8 100644
--- a/overrides.nix
+++ b/overrides.nix
@@ -11,23 +11,6 @@ let
     ];
   });
 
-  renameLiteral = pname: (self: super: drv: drv.overrideAttrs(old: {
-    src = old.src.override { inherit pname; };
-  }));
-
-  renameUnderscore = self: super: drv: drv.overrideAttrs(old: {
-    src = old.src.override { pname = builtins.replaceStrings ["-"] ["_"] old.pname; };
-  });
-
-  renameCapital = let
-    capitalise = s: let
-      len = builtins.stringLength s;
-      first = lib.toUpper (builtins.substring 0 1 s);
-    in first + builtins.substring 1 len s;
-  in self: super: drv: drv.overrideAttrs(old: {
-    src = old.src.override { pname = capitalise old.pname; };
-  });
-
   # Chain multiple overrides into a single one
   composeOverrides = overrides:
     (self: super: drv: builtins.foldl' (drv: override: override self super drv) drv overrides);
@@ -39,8 +22,6 @@ let
 
 in {
 
-  babel = renameCapital;
-
   django-bakery = self: super: drv: drv.overrideAttrs(old: {
     configurePhase = ''
       if ! test -e LICENSE; then
@@ -49,20 +30,13 @@ in {
     '' + (getAttrDefault "configurePhase" old "");
   });
 
-  vat-moss = renameUnderscore;
-
   django = composeOverrides [
-    renameCapital
     (self: super: drv: drv.overrideAttrs(old: {
       propagatedNativeBuildInputs = (getAttrDefault "propagatedNativeBuildInputs" old [])
       ++ [ pkgs.gettext ];
     }))
   ];
 
-  cachecontrol = renameLiteral "CacheControl";
-
-  click = renameCapital;
-
   cffi = self: super: drv: drv.overrideAttrs(old: {
     buildInputs = old.buildInputs ++ [ pkgs.libffi ];
   });
@@ -75,20 +49,10 @@ in {
     buildInputs = old.buildInputs ++ [ pkgs.openssl ];
   });
 
-  django-compressor = renameUnderscore;
-
-  django-csp = renameUnderscore;
-
-  django-context-decorator = renameUnderscore;
-
-  markdown = renameCapital;
-
   markupsafe = self: super: drv: drv.overrideAttrs(old: {
     src = old.src.override { pname = builtins.replaceStrings [ "markupsafe" ] [ "MarkupSafe"] old.pname; };
   });
 
-  pyyaml = renameLiteral "PyYAML";
-
   hypothesis = addSetupTools;
 
   pillow = let
@@ -98,14 +62,10 @@ in {
       buildInputs = with pkgs; [ freetype libjpeg zlib libtiff libwebp tcl lcms2 ]
         ++ old.buildInputs;
     });
-  in composeOverrides [ renameCapital pillowOverride ];
+  in pillowOverride;
 
   pytest = addSetupTools;
 
-  pyopenssl = renameLiteral "pyOpenSSL";
-
-  pypdf2 = renameLiteral "PyPDF2";
-
   pytest-mock = addSetupTools;
 
   six = addSetupTools;
@@ -114,24 +74,14 @@ in {
 
   zipp = addSetupTools;
 
-  importlib-metadata = composeOverrides [ renameUnderscore addSetupTools ];
-
-  importlib-resources = composeOverrides [ renameUnderscore ];
-
-  typing-extensions = renameUnderscore;
+  importlib-metadata = addSetupTools;
 
   pluggy = addSetupTools;
 
-  pre-commit = renameUnderscore;
-
   jsonschema = addSetupTools;
 
-  jinja2 = renameCapital;
-
   python-dateutil = addSetupTools;
 
-  pygments = renameCapital;
-
   numpy = self: super: drv: drv.overrideAttrs(old: {
     nativeBuildInputs = old.nativeBuildInputs ++ [ pkgs.gfortran ];
     buildInputs = old.buildInputs ++ [ pkgs.openblasCompat ];
@@ -157,6 +107,4 @@ in {
 
   keyring = addSetupTools;
 
-  secretstorage = renameLiteral "SecretStorage";
-
 }