pr-size.yml

name: PR Size

on:
  pull_request_target:
    types: [opened, reopened, synchronize, ready_for_review, converted_to_draft]

permissions:
  contents: read

jobs:
  prepare-config:
    name: Prepare PR size config
    runs-on: ubuntu-24.04
    outputs:
      labels_json: ${{ steps.config.outputs.labels_json }}
    steps:
      - id: config
        name: Build PR size label config
        uses: actions/github-script@v8
        with:
          result-encoding: string
          script: |
            const managedLabels = [
              {
                name: "size:XS",
                color: "0e8a16",
                description: "0-9 effective changed lines (test files excluded in mixed PRs).",
              },
              {
                name: "size:S",
                color: "5ebd3e",
                description: "10-29 effective changed lines (test files excluded in mixed PRs).",
              },
              {
                name: "size:M",
                color: "fbca04",
                description: "30-99 effective changed lines (test files excluded in mixed PRs).",
              },
              {
                name: "size:L",
                color: "fe7d37",
                description: "100-499 effective changed lines (test files excluded in mixed PRs).",
              },
              {
                name: "size:XL",
                color: "d93f0b",
                description: "500-999 effective changed lines (test files excluded in mixed PRs).",
              },
              {
                name: "size:XXL",
                color: "b60205",
                description: "1,000+ effective changed lines (test files excluded in mixed PRs).",
              },
            ];

            core.setOutput("labels_json", JSON.stringify(managedLabels));
  sync-label-definitions:
    name: Sync PR size label definitions
    needs: prepare-config
    if: github.event_name != 'pull_request_target'
    runs-on: ubuntu-24.04
    permissions:
      contents: read
      issues: write
    steps:
      - name: Ensure PR size labels exist
        uses: actions/github-script@v8
        env:
          PR_SIZE_LABELS_JSON: ${{ needs.prepare-config.outputs.labels_json }}
        with:
          script: |
            const managedLabels = JSON.parse(process.env.PR_SIZE_LABELS_JSON ?? "[]");

            for (const label of managedLabels) {
              try {
                const { data: existing } = await github.rest.issues.getLabel({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  name: label.name,
                });

                if (
                  existing.color !== label.color ||
                  (existing.description ?? "") !== label.description
                ) {
                  await github.rest.issues.updateLabel({
                    owner: context.repo.owner,
                    repo: context.repo.repo,
                    name: label.name,
                    color: label.color,
                    description: label.description,
                  });
                }
              } catch (error) {
                if (error.status !== 404) {
                  throw error;
                }

                try {
                  await github.rest.issues.createLabel({
                    owner: context.repo.owner,
                    repo: context.repo.repo,
                    name: label.name,
                    color: label.color,
                    description: label.description,
                  });
                } catch (createError) {
                  if (createError.status !== 422) {
                    throw createError;
                  }
                }
              }
            }
  label:
    name: Label PR size
    needs: prepare-config
    if: github.event_name == 'pull_request_target'
    runs-on: ubuntu-24.04
    permissions:
      contents: read
      issues: read
      pull-requests: write
    concurrency:
      group: pr-size-${{ github.event.pull_request.number }}
      cancel-in-progress: true
    steps:
      - name: Checkout base repository
        uses: actions/checkout@v4
        with:
          fetch-depth: 0
      - name: Sync PR size label
        uses: actions/github-script@v8
        env:
          PR_SIZE_LABELS_JSON: ${{ needs.prepare-config.outputs.labels_json }}
        with:
          script: |
            const { execFileSync } = require("node:child_process");

            const issueNumber = context.payload.pull_request.number;
            const baseSha = context.payload.pull_request.base.sha;
            const headSha = context.payload.pull_request.head.sha;
            const headTrackingRef = `refs/remotes/pr-size/${issueNumber}`;
            const managedLabels = JSON.parse(process.env.PR_SIZE_LABELS_JSON ?? "[]");
            const managedLabelNames = new Set(managedLabels.map((label) => label.name));
            // Keep this aligned with the repo's test entrypoints and test-only support files.
            const testExcludePathspecs = [
              ":(glob,exclude)**/__tests__/**",
              ":(glob,exclude)**/test/**",
              ":(glob,exclude)**/tests/**",
              ":(glob,exclude)apps/server/integration/**",
              ":(glob,exclude)**/*.test.*",
              ":(glob,exclude)**/*.spec.*",
              ":(glob,exclude)**/*.browser.*",
              ":(glob,exclude)**/*.integration.*",
            ];

            const sumNumstat = (text) =>
              text
                .split("\n")
                .filter(Boolean)
                .reduce((total, line) => {
                  const [insertionsRaw = "0", deletionsRaw = "0"] = line.split("\t");
                  const additions =
                    insertionsRaw === "-" ? 0 : Number.parseInt(insertionsRaw, 10) || 0;
                  const deletions =
                    deletionsRaw === "-" ? 0 : Number.parseInt(deletionsRaw, 10) || 0;

                  return total + additions + deletions;
                }, 0);

            const resolveSizeLabel = (totalChangedLines) => {
              if (totalChangedLines < 10) {
                return "size:XS";
              }

              if (totalChangedLines < 30) {
                return "size:S";
              }

              if (totalChangedLines < 100) {
                return "size:M";
              }

              if (totalChangedLines < 500) {
                return "size:L";
              }

              if (totalChangedLines < 1000) {
                return "size:XL";
              }

              return "size:XXL";
            };

            execFileSync("git", ["fetch", "--no-tags", "origin", baseSha], {
              stdio: "inherit",
            });

            execFileSync(
              "git",
              ["fetch", "--no-tags", "origin", `+refs/pull/${issueNumber}/head:${headTrackingRef}`],
              {
                stdio: "inherit",
              },
            );

            const resolvedHeadSha = execFileSync("git", ["rev-parse", headTrackingRef], {
              encoding: "utf8",
            }).trim();

            if (resolvedHeadSha !== headSha) {
              core.warning(
                `Fetched head SHA ${resolvedHeadSha} does not match pull request head SHA ${headSha}; using fetched ref for sizing.`,
              );
            }

            execFileSync("git", ["cat-file", "-e", `${baseSha}^{commit}`], {
              stdio: "inherit",
            });

            const diffArgs = [
              "diff",
              "--numstat",
              "--ignore-all-space",
              "--ignore-blank-lines",
              `${baseSha}...${resolvedHeadSha}`,
            ];

            const totalChangedLines = sumNumstat(
              execFileSync(
                "git",
                diffArgs,
                { encoding: "utf8" },
              ),
            );
            const nonTestChangedLines = sumNumstat(
              execFileSync("git", [...diffArgs, "--", ".", ...testExcludePathspecs], {
                encoding: "utf8",
              }),
            );
            const testChangedLines = Math.max(0, totalChangedLines - nonTestChangedLines);

            const changedLines = nonTestChangedLines === 0 ? testChangedLines : nonTestChangedLines;
            const nextLabelName = resolveSizeLabel(changedLines);

            const { data: currentLabels } = await github.rest.issues.listLabelsOnIssue({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: issueNumber,
              per_page: 100,
            });

            for (const label of currentLabels) {
              if (!managedLabelNames.has(label.name) || label.name === nextLabelName) {
                continue;
              }

              try {
                await github.rest.issues.removeLabel({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  issue_number: issueNumber,
                  name: label.name,
                });
              } catch (removeError) {
                if (removeError.status !== 404) {
                  throw removeError;
                }
              }
            }

            if (!currentLabels.some((label) => label.name === nextLabelName)) {
              await github.rest.issues.addLabels({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: issueNumber,
                labels: [nextLabelName],
              });
            }

            const classification =
              nonTestChangedLines === 0
                ? testChangedLines > 0
                  ? "test-only PR"
                  : "no line changes"
                : testChangedLines > 0
                  ? "test lines excluded"
                  : "all non-test changes";

            core.info(
              `PR #${issueNumber}: ${nonTestChangedLines} non-test lines, ${testChangedLines} test lines, ${changedLines} effective lines -> ${nextLabelName} (${classification})`,
            );