From cd9463e572f31b82a73cdab6db6b53f3a1237b3e Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Fri, 12 Apr 2019 22:35:13 +0200
Subject: Use Nix to fetch ATOM feed

Fetching external resources during the actual build became problematic
after the last major Nix update (build purity was improved).

The sensible way of doing things in Nix seems to be to declare ALL
build dependencies prior to the actual build -- this includes
e.g. ATOM feeds to be aggregated.

I am probably not going to do the same for the individual repository
feeds as this feature is going to be replaced with a more general
_microblog_-like subpage.
---
 default.nix                    | 16 +++++++++-------
 source/01_raw/article_feed.xsl | 10 ++++------
 utility/fetch_feed.sh          |  2 +-
 3 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/default.nix b/default.nix
index d2c031d..36edbe9 100644
--- a/default.nix
+++ b/default.nix
@@ -1,10 +1,6 @@
-{ system ? builtins.currentSystem }:
+{ pkgs ? import <nixpkgs> { }, mypkgs ? import <mypkgs> { }, ... }:
 
-let
-  pkgs    = import <nixpkgs> { inherit system; };
-  mypkgs  = import (fetchTarball "https://pkgs.kummerlaender.eu/nixexprs.tar.gz") { };
-
-in pkgs.stdenv.mkDerivation {
+pkgs.stdenv.mkDerivation {
   name = "Overview";
 
   src = ./.;
@@ -18,7 +14,13 @@ in pkgs.stdenv.mkDerivation {
     mypkgs.make-xslt
   ];
 
-  installPhase = ''
+  installPhase = let
+    blog_feed = builtins.fetchurl {
+      url = "https://blog.kummerlaender.eu/atom.xml";
+    };
+  in ''
+    cp ${blog_feed} source/00_content/article_feed.xml
+
     make-xslt
     mkdir $out
     cp -Lr target/99_result/* $out
diff --git a/source/01_raw/article_feed.xsl b/source/01_raw/article_feed.xsl
index 96f918d..18c8d51 100644
--- a/source/01_raw/article_feed.xsl
+++ b/source/01_raw/article_feed.xsl
@@ -2,7 +2,6 @@
 <xsl:stylesheet
 	version="1.0"
 	xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
-	xmlns:atom="http://www.w3.org/2005/Atom"
 	xmlns:InputXSLT="function.inputxslt.application"
 	exclude-result-prefixes="InputXSLT"
 >
@@ -11,14 +10,13 @@
 <xsl:include href="[utility/remove_namespace.xsl]"/>
 
 <xsl:variable name="meta">
-	<datasource type="main"  mode="full" source="00_content/meta.xml" target="meta"/>
+	<datasource type="main"    mode="full" source="00_content/article_feed.xml" target="feed"/>
+	<datasource type="support" mode="full" source="00_content/meta.xml" target="meta"/>
 	<target     mode="plain" value="article_feed.xml"/>
 </xsl:variable>
 
-<xsl:template match="meta">
-	<xsl:apply-templates mode="remove_namespace" select="InputXSLT:external-command(
-		'curl http://blog.kummerlaender.eu/atom.xml'
-	)/self::command/atom:feed/atom:entry[position() &lt;= $root/meta/overview/article_count]"/>
+<xsl:template match="feed">
+	<xsl:apply-templates mode="remove_namespace" select="entry[position() &lt;= $root/meta/overview/article_count]"/>
 </xsl:template>
 
 </xsl:stylesheet>
diff --git a/utility/fetch_feed.sh b/utility/fetch_feed.sh
index 45dbc6c..37393f6 100755
--- a/utility/fetch_feed.sh
+++ b/utility/fetch_feed.sh
@@ -1,3 +1,3 @@
-#!/bin/sh
+#!/usr/bin/env sh
 
 curl $1 | sed  -e 's~^\([\*]\)\{3\}~\t\t\*~g' -e 's~^\([\*]\)\{2\}~\t\*~g'
-- 
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