CD: Add build status reporing

Squashed commit of the following:

commit ecfee6a
Author: cyqsimon <[email protected]>
Date:   Thu Oct 12 13:30:10 2023 +0800

    Only run reporting job when build ID output is not empty

    - See dorny/paths-filter#66

commit c286138
Author: cyqsimon <[email protected]>
Date:   Thu Oct 12 13:26:18 2023 +0800

    Better job & step naming

commit fa80712
Author: cyqsimon <[email protected]>
Date:   Thu Oct 12 13:25:17 2023 +0800

    rm mock build ID

commit 445f56f
Author: cyqsimon <[email protected]>
Date:   Thu Oct 12 13:24:18 2023 +0800

    `jq` is installed by default

commit 3e526a0
Author: cyqsimon <[email protected]>
Date:   Thu Oct 12 13:18:31 2023 +0800

    Use a running mock build ID

commit fd1c375
Author: cyqsimon <[email protected]>
Date:   Thu Oct 12 13:14:29 2023 +0800

    Query API until build completion

commit ddd091a
Author: cyqsimon <[email protected]>
Date:   Thu Oct 12 12:53:26 2023 +0800

    Create job matrix using JSON array output

commit 139dc51
Author: cyqsimon <[email protected]>
Date:   Thu Oct 12 12:47:43 2023 +0800

    Generate JSON array correctly

commit 1fd4c8e
Author: cyqsimon <[email protected]>
Date:   Thu Oct 12 12:42:21 2023 +0800

    Correctly output whole array

commit 627b1e5
Author: cyqsimon <[email protected]>
Date:   Thu Oct 12 12:39:56 2023 +0800

    Add mock build IDs

commit 4e0f5d6
Author: cyqsimon <[email protected]>
Date:   Thu Oct 12 12:36:20 2023 +0800

    add build ID output

.github/workflows/rebuild-changed.yaml

@@ -14,6 +14,8 @@ jobs:
     name: Trigger rebuild for modified .spec files
     runs-on: ubuntu-latest
     timeout-minutes: 3
+    outputs:
+      builds: ${{ steps.send-request.outputs.builds }}
     steps:
       - name: Install ripgrep
         run: sudo apt-get install -y ripgrep
@@ -28,12 +30,49 @@ jobs:
           files: specs/*.spec
 
       - name: Send rebuild request to COPR
+        id: send-request
         env:
           URL: ${{ secrets.COPR_WEBHOOK_URL }}
         run: |
+          BUILD_IDS=()
           for FILE in ${{ steps.spec-modified.outputs.modified_files }}; do
             PKG=$(rg '^Name:\s*([\w\d_\-]+)\s*$' --replace '$1' $FILE)
             echo "Package $PKG changed (Spec file: $FILE); sending rebuild request"
             BUILD_ID=$(curl -Ssf -X POST "$URL/$PKG")
             echo "Build submitted: https://copr.fedorainfracloud.org/coprs/build/$BUILD_ID"
+            BUILD_IDS+=( "$BUILD_ID" )
+          done
+          echo "builds=$(printf '%s\n' "${BUILD_IDS[@]}" | jq -ncR '[inputs] | map(select(. != ""))')" >> "$GITHUB_OUTPUT"
+
+  report-status:
+    name: Report build status
+    needs: trigger-rebuild-for-modified
+    runs-on: ubuntu-latest
+    if: needs.trigger-rebuild-for-modified.outputs.builds != '[]'
+    strategy:
+      matrix:
+        build_id: ${{ fromJson(needs.trigger-rebuild-for-modified.outputs.builds) }}
+    steps:
+      - name: Report status
+        run: |
+          while true; do
+            STATUS=$(curl -Ssf "https://copr.fedorainfracloud.org/api_3/build/${{ matrix.build_id }}" | jq -r '.state')
+            case $STATUS in
+              pending | starting | importing | imported | waiting | running)
+                echo "Build is $STATUS. Querying again in 15s."
+                sleep 15
+                ;;
+              succeeded | forked)
+                echo "Build $STATUS."
+                exit 0
+                ;;
+              failed | canceled | skipped)
+                echo "Build $STATUS."
+                exit 1
+                ;;
+              *)
+                echo "COPR API reported unknown status: $STATUS."
+                exit 2
+                ;;
+            esac
           done