[Bot] Revive prdoc bot (#5648)

Prdoc bot was deleted in
https://github.com/paritytech/polkadot-sdk/pull/5457 just after being
added in https://github.com/paritytech/polkadot-sdk/pull/5331 without
replacement.
Now bringing it back until it is integrated into the new command
structure.

Formatting is now also fixed, such that the title is always first and
the description renders correctly.

---------

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

.github/scripts/generate-prdoc.py

@@ -48,9 +48,8 @@ def create_prdoc(pr, audience, title, description, patch, bump, force):
 	else:
 		print(f"No preexisting PrDoc for PR {pr}")
 
-	prdoc = { "doc": [{}], "crates": [] }
+	prdoc = { "title": title, "doc": [{}], "crates": [] }
 
-	prdoc["title"] = title
 	prdoc["doc"][0]["audience"] = audience
 	prdoc["doc"][0]["description"] = description
 
@@ -58,13 +57,19 @@ def create_prdoc(pr, audience, title, description, patch, bump, force):
 
 	modified_paths = []
 	for diff in whatthepatch.parse_patch(patch):
-		modified_paths.append(diff.header.new_path)
+		new_path = diff.header.new_path
+		# Sometimes this lib returns `/dev/null` as the new path...
+		if not new_path.startswith("/dev"):
+			modified_paths.append(new_path)
 
 	modified_crates = {}
 	for p in modified_paths:
 		# Go up until we find a Cargo.toml
 		p = os.path.join(workspace.path, p)
 		while not os.path.exists(os.path.join(p, "Cargo.toml")):
+			print(f"Could not find Cargo.toml in {p}")
+			if p == '/':
+				exit(1)
 			p = os.path.dirname(p)
 		
 		with open(os.path.join(p, "Cargo.toml")) as f:
@@ -95,9 +100,19 @@ def create_prdoc(pr, audience, title, description, patch, bump, force):
 
 	# write the parsed PR documentation back to the file
 	with open(path, "w") as f:
-		yaml.dump(prdoc, f)
+		yaml.dump(prdoc, f, sort_keys=False)
 		print(f"PrDoc for PR {pr} written to {path}")
 
+# Make the `description` a multiline string instead of escaping \r\n.
+def setup_yaml():
+	def yaml_multiline_string_presenter(dumper, data):
+		if len(data.splitlines()) > 1:
+			data = '\n'.join([line.rstrip() for line in data.strip().splitlines()])
+			return dumper.represent_scalar('tag:yaml.org,2002:str', data, style='|')
+		return dumper.represent_scalar('tag:yaml.org,2002:str', data)
+
+	yaml.add_representer(str, yaml_multiline_string_presenter)
+
 def parse_args():
 	parser = argparse.ArgumentParser()
 	parser.add_argument("--pr", type=int, required=True)
@@ -108,6 +123,7 @@ def parse_args():
 
 if __name__ == "__main__":
 	args = parse_args()
-	force = True if args.force.lower() == "true" else False
+	force = True if (args.force or "false").lower() == "true" else False
 	print(f"Args: {args}, force: {force}")
+	setup_yaml()
 	from_pr_number(args.pr, args.audience, args.bump, force)

.github/workflows/command-prdoc.yml

+name: Command PrDoc
+
+on:
+  workflow_dispatch:
+    inputs:
+      pr:
+        type: number
+        description: Number of the Pull Request
+        required: true
+      bump:
+        type: choice
+        description: Default bump level for all crates
+        default: "TODO"
+        required: true
+        options:
+          - "TODO"
+          - "no change"
+          - "patch"
+          - "minor"
+          - "major"
+      audience:
+        type: choice
+        description: Audience of the PrDoc
+        default: "TODO"
+        required: true
+        options:
+          - "TODO"
+          - "Runtime Dev"
+          - "Runtime User"
+          - "Node Dev"
+          - "Node User"
+      overwrite:
+        type: choice
+        description: Overwrite existing PrDoc
+        default: "true"
+        required: true
+        options:
+          - "true"
+          - "false"
+
+concurrency:
+  group: command-prdoc
+  cancel-in-progress: true
+
+jobs:
+  set-image:
+    runs-on: ubuntu-latest
+    outputs:
+      IMAGE: ${{ steps.set_image.outputs.IMAGE }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - id: set_image
+        run: cat .github/env >> $GITHUB_OUTPUT
+  cmd-prdoc:
+    needs: [set-image]
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
+    container:
+      image: ${{ needs.set-image.outputs.IMAGE }}
+    permissions:
+      contents: write
+      pull-requests: write
+    steps:
+      - name: Download repo
+        uses: actions/checkout@v4
+      - name: Install gh cli
+        id: gh
+        uses: ./.github/actions/set-up-gh
+        with:
+          pr-number: ${{ inputs.pr }}
+          GH_TOKEN: ${{ github.token }}
+      - name: Generate PrDoc
+        run: |
+          python3 -m pip install -q cargo-workspace PyGithub whatthepatch pyyaml toml
+
+          python3 .github/scripts/generate-prdoc.py --pr "${{ inputs.pr }}" --bump "${{ inputs.bump }}" --audience "${{ inputs.audience }}" --force "${{ inputs.overwrite }}"
+
+      - name: Report failure
+        if: ${{ failure() }}
+        run: gh pr comment ${{ inputs.pr }} --body "<h2>Command failed ❌</h2> Run by @${{ github.actor }} for <code>${{ github.workflow }}</code> failed. See logs <a href=\"$RUN\">here</a>."
+        env:
+          RUN: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}
+          GH_TOKEN: ${{ github.token }}
+      - name: Push Commit
+        uses: stefanzweifel/git-auto-commit-action@v5
+        with:
+          commit_message: Add PrDoc (auto generated)
+          branch: ${{ steps.gh.outputs.branch }}
+          file_pattern: 'prdoc/*.prdoc'