From aefcfdd0ae2aa41adb3d1106752b6a291ef1d80f Mon Sep 17 00:00:00 2001
From: Philip McGrath <philip@philipmcgrath.com>
Date: Wed, 18 May 2022 14:10:50 -0400
Subject: guix: Add elm-build-system.
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* gnu/packages/patches/elm-offline-package-registry.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/elm.scm (elm): Use it.
* guix/build-system/elm.scm, guix/build/elm-build-system.scm,
tests/elm.scm: New files.
* Makefile.scm (MODULES, SCM_TESTS): Add them.
* doc/guix.texi (Build Systems): Document 'elm-build-system'.
* doc/contributing.texi (Elm Packages): New section. Document naming
conventions and utilities.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>
---
 gnu/local.mk                                       |  1 +
 gnu/packages/elm.scm                               |  4 +-
 .../patches/elm-offline-package-registry.patch     | 71 ++++++++++++++++++++++
 3 files changed, 75 insertions(+), 1 deletion(-)
 create mode 100644 gnu/packages/patches/elm-offline-package-registry.patch

(limited to 'gnu')

diff --git a/gnu/local.mk b/gnu/local.mk
index 70efa16c63..6274f43566 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -1024,6 +1024,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/einstein-build.patch			\
   %D%/packages/patches/elfutils-tests-ptrace.patch		\
   %D%/packages/patches/elixir-path-length.patch			\
+  %D%/packages/patches/elm-offline-package-registry.patch	\
   %D%/packages/patches/elm-reactor-static-files.patch		\
   %D%/packages/patches/elogind-revert-polkit-detection.patch	\
   %D%/packages/patches/emacs-exec-path.patch			\
diff --git a/gnu/packages/elm.scm b/gnu/packages/elm.scm
index a3863e6e6f..35bdcc65f5 100644
--- a/gnu/packages/elm.scm
+++ b/gnu/packages/elm.scm
@@ -25,6 +25,7 @@
   #:use-module (gnu packages haskell-xyz)
   #:use-module (gnu packages haskell-web)
   #:use-module (guix build-system haskell)
+  #:use-module (guix build-system elm)
   #:use-module (guix gexp)
   #:use-module (guix git-download)
   #:use-module ((guix licenses) #:prefix license:)
@@ -53,7 +54,8 @@
        (sha256
         (base32 "1rdg3xp3js9xadclk3cdypkscm5wahgsfmm4ldcw3xswzhw6ri8w"))
        (patches
-        (search-patches "elm-reactor-static-files.patch"))))
+        (search-patches "elm-reactor-static-files.patch"
+                        "elm-offline-package-registry.patch"))))
     (build-system haskell-build-system)
     (arguments
      (list
diff --git a/gnu/packages/patches/elm-offline-package-registry.patch b/gnu/packages/patches/elm-offline-package-registry.patch
new file mode 100644
index 0000000000..761ec69878
--- /dev/null
+++ b/gnu/packages/patches/elm-offline-package-registry.patch
@@ -0,0 +1,71 @@
+From 06563409e6f2b1cca7bc1b27e31efd07a7569da8 Mon Sep 17 00:00:00 2001
+From: Philip McGrath <philip@philipmcgrath.com>
+Date: Thu, 14 Apr 2022 22:41:04 -0400
+Subject: [PATCH] minimal support for offline builds
+
+Normally, Elm performs HTTP requests before building to obtain or
+update its list of all registed packages and their versions.
+This is problematic in the Guix build environment.
+
+This patch causes Elm to check if the `GUIX_ELM_OFFLINE_REGISTRY_FILE`
+is set and, if so, to use the contents of the file it specifies as
+though it were the response from
+https://package.elm-lang.org/all-packages.
+
+This patch does not attempt to add more general support for offline
+builds. In particular, it does not attempt to support incremental
+updates to the package registry cache file. See also discussion at
+https://discourse.elm-lang.org/t/private-package-tool-spec/6779/25.
+---
+ builder/src/Deps/Registry.hs | 25 +++++++++++++++++++++----
+ 1 file changed, 21 insertions(+), 4 deletions(-)
+
+diff --git a/builder/src/Deps/Registry.hs b/builder/src/Deps/Registry.hs
+index 8d7def98..70cf3622 100644
+--- a/builder/src/Deps/Registry.hs
++++ b/builder/src/Deps/Registry.hs
+@@ -18,6 +18,8 @@ import Control.Monad (liftM2)
+ import Data.Binary (Binary, get, put)
+ import qualified Data.List as List
+ import qualified Data.Map.Strict as Map
++import System.Environment as Env
++import qualified Data.ByteString as BS
+ 
+ import qualified Deps.Website as Website
+ import qualified Elm.Package as Pkg
+@@ -190,13 +192,28 @@ getVersions' name (Registry _ versions) =
+ post :: Http.Manager -> String -> D.Decoder x a -> (a -> IO b) -> IO (Either Exit.RegistryProblem b)
+ post manager path decoder callback =
+   let
+-    url = Website.route path []
+-  in
+-  Http.post manager url [] Exit.RP_Http $
+-    \body ->
++    mkBodyCallback url body =
+       case D.fromByteString decoder body of
+         Right a -> Right <$> callback a
+         Left _ -> return $ Left $ Exit.RP_Data url body
++    postOnline url cb =
++      Http.post manager url [] Exit.RP_Http cb
++    performPost f url =
++      f url (mkBodyCallback url)
++  in
++    do
++      maybeFile <- Env.lookupEnv "GUIX_ELM_OFFLINE_REGISTRY_FILE"
++      case (path, maybeFile) of
++        ( "/all-packages", Just file ) ->
++          performPost postOffline file
++        ( _, _ ) ->
++          -- don't know how to handle other endpoints yet
++          performPost postOnline (Website.route path [])
++
++postOffline :: String -> (BS.ByteString -> IO a) -> IO a
++postOffline file callback = do
++  body <- BS.readFile file
++  callback body
+ 
+ 
+ 
+-- 
+2.32.0
+
-- 
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