blacklist get-rep: re-implement to query repos instead of blacklist.txt

Rationale: https://lists.parabola.nu/pipermail/dev/2017-October/005936.html

This makes get-rep a general-purpose tool for finding replacements and
providers of any package, not just blacklisted-ones. It works equally
well reading from full blacklist.txt lines, just pkgname lines, and
unwittingly; a single line with many pkgnames.

Some caveats for further discussion:

 - This changes behavior from showing just one replacement/provider to
   _all_ replacements and providers (including pkgname itself) in the repos.

 - By "repos" I mean the repos the executing machine is configured to
   access. This could be changed in the future with `expac --config`
   if more package databases are desired (e.g. different
   architecture).

 - Results are shown using the "repo/pkgname ..." format rather than
   just "pkgname ...". I think this makes the program more useful.

 - Results aren't reordered to ensure that the first provider of
   pkgname is pkgname itself. Order will be as expected otherwise, by
   virtue of expac parsing repos in order.

2 files changed, 23 insertions, 6 deletions

diff --git a/src/lib/blacklist.sh b/src/lib/blacklist.sh
index e3d976b..c092ed3 100755
--- a/src/lib/blacklist.sh
+++ b/src/lib/blacklist.sh
@@ -93,7 +93,24 @@ blacklist-get-pkg() {
 # Usage: blacklist-cat | blacklist-get-rep
 # Prints only the replacement package field of the blacklist line(s) on stdin.
 blacklist-get-rep() {
-	blacklist-normalize | cut -d: -f2
+	local -a targets=($(blacklist-get-pkg))
+	expac -Ss '%r/%n %n %P %R' | awk -v arr="${targets[*]}" '
+	      {
+	          gsub("[=<>]+[^[:blank:]]*", "", $0) # discard versioning
+	          # build pkg -> providers table from pkg -> provides
+	          for (provided = 2; provided <= NF; ++provided) {
+	              if (! seen[$1 " " $provided]++) {
+	                  providers[$provided] = providers[$provided] $1 " "
+	              }
+	          }
+	      }
+	      END {
+	          split(arr, targets, " ")
+	          for (pkg in targets) {
+	              sub("[ \t]+$", "", providers[targets[pkg]])
+	              print providers[targets[pkg]]
+	          }
+	      }'
 }
 
 # Usage: blacklist-cat | blacklist-get-url
diff --git a/test/lib-blacklist-test.sh b/test/lib-blacklist-test.sh
index 1f8c518..7b88b72 100755
--- a/test/lib-blacklist-test.sh
+++ b/test/lib-blacklist-test.sh
@@ -8,16 +8,16 @@ _blacklist_url=https://projects.parabola.nu/blacklist.git/plain/blacklist.txt
 it_works_with_just_pkgname() {
 	v="$(libreblacklist normalize <<<skype)"; [[ $v == 'skype::::' ]]
 	v="$(libreblacklist get-pkg <<<skype)"; [[ $v == skype ]]
-	libreblacklist get-rep <<<skype | equals $'\n'
+	libreblacklist get-rep <<<irreplaceable | equals $'\n'
 	libreblacklist get-url <<<skype | equals $'\n'
 	libreblacklist get-reason <<<skype | equals $'\n'
 }
 
 it_works_with_everything_set() {
-	line='linux:linux-libre:parabola:id:[semifree] blobs and firmware'
+	line='linux:conflict:parabola:id:[semifree] blobs and firmware'
 	v="$(libreblacklist normalize <<<"$line")"; [[ $v == "$line" ]]
 	v="$(libreblacklist get-pkg <<<"$line")"; [[ $v == 'linux' ]]
-	v="$(libreblacklist get-rep <<<"$line")"; [[ $v == 'linux-libre' ]]
+	v="$(libreblacklist get-rep <<<"$line")"; [[ $v == 'libre/linux-libre' ]]
 	v="$(libreblacklist get-url <<<"$line")"; [[ $v == 'https://labs.parabola.nu/issues/id' ]]
 	v="$(libreblacklist get-reason <<<"$line")"; [[ $v == '[semifree] blobs and firmware' ]]
 }
@@ -37,10 +37,10 @@ it_normalizes_correctly() {
 }
 
 it_works_with_colons_in_reason() {
-	line='package:replacement:parabola:id:my:reason'
+	line='package:conflict:parabola:id:my:reason'
 	v="$(libreblacklist normalize <<<"$line")"; [[ $v == "$line" ]]
 	v="$(libreblacklist get-pkg <<<"$line")"; [[ $v == 'package' ]]
-	v="$(libreblacklist get-rep <<<"$line")"; [[ $v == 'replacement' ]]
+	libreblacklist get-rep <<<"$line" | equals $'\n'
 	v="$(libreblacklist get-url <<<"$line")"; [[ $v == 'https://labs.parabola.nu/issues/id' ]]
 	v="$(libreblacklist get-reason <<<"$line")"; [[ $v == 'my:reason' ]]
 }