apiVersion: tekton.dev/v1alpha1
kind: Task
metadata:
  name: check-git-files-changed
  annotations:
    description: |
      Returns "passed" in the "check" result if any of the files changed
      in the source on the workspace matches the regular expression.
      Returns a "files" result as a list of files modified by the PR that
      match the regex in the parameters.
    ci.tekton.dev/condition: |
      The result of this task is used to evaluate a condition.
      Events from this task are ignored downstream, when it comes to update the CI job status.
spec:
  params:
    - name: gitCloneDepth
      description: Number of commits + 1
    - name: regex
      description: Regular expression to match files changed
  workspaces:
    - name: input
  results:
    - name: check
      description: passed or failed
    - name: files
      description: list of files modified that match
  steps:
    - name: check-files-changed
      image: alpine/git
      env:
        - name: GIT_CLONE_DEPTH
          value: $(params.gitCloneDepth)
        - name: REGEX
          value: $(params.regex)
      script: |
        #!/bin/sh
        set -ex
        set -o pipefail
        BACK="HEAD~$(( ${GIT_CLONE_DEPTH} - 1 ))"
        CHECK="failed"
        cd $(workspaces.input.path)
        git diff-tree --no-commit-id --name-only -r HEAD $BACK | \
            grep -E "${REGEX}" > $(results.files.path) || true
        git diff-tree --no-commit-id --name-only -r HEAD $BACK | \
            grep -E "${REGEX}" && CHECK="passed"
        printf $CHECK > $(results.check.path)