name: "Create Gitea Pull Request"
description: "Creates a pull request on a Gitea repository via the REST API"

inputs:
  gitea_url:
    description: "Base URL of the Gitea instance"
    required: false
    default: "https://gitea.psi.ch"
  repository:
    description: "Target repository as owner/repo"
    required: false
    default: ""
  token:
    description: "Gitea token with pull-request write access"
    required: true
  title:
    description: "Pull request title"
    required: true
  body:
    description: "Pull request description"
    required: false
    default: ""
  head:
    description: "Source branch. Same-repo: branch name. Fork: owner:branch"
    required: true
  base:
    description: "Target branch"
    required: false
    default: "main"
  allow_existing:
    description: "If a matching open PR already exists, succeed and return it instead of failing"
    required: false
    default: "true"

outputs:
  number:
    description: "Pull request number"
    value: ${{ steps.create_pr.outputs.number }}
  url:
    description: "API URL of the pull request"
    value: ${{ steps.create_pr.outputs.url }}
  html_url:
    description: "Web URL of the pull request"
    value: ${{ steps.create_pr.outputs.html_url }}

runs:
  using: "composite"
  steps:
    - id: create_pr
      name: Create Pull Request
      shell: bash
      env:
        INPUT_GITEA_URL: ${{ inputs.gitea_url }}
        INPUT_REPOSITORY: ${{ inputs.repository }}
        INPUT_TOKEN: ${{ inputs.token }}
        INPUT_TITLE: ${{ inputs.title }}
        INPUT_BODY: ${{ inputs.body }}
        INPUT_HEAD: ${{ inputs.head }}
        INPUT_BASE: ${{ inputs.base }}
        INPUT_ALLOW_EXISTING: ${{ inputs.allow_existing }}
        GITHUB_REPOSITORY: ${{ github.repository }}
      run: |
        set -euo pipefail

        GITEA_URL="${INPUT_GITEA_URL:-https://gitea.psi.ch}"
        REPOSITORY="${INPUT_REPOSITORY:-${GITHUB_REPOSITORY}}"
        HEAD="${INPUT_HEAD}"
        BASE="${INPUT_BASE:-main}"
        ALLOW_EXISTING="${INPUT_ALLOW_EXISTING:-true}"

        if [[ ! "${REPOSITORY}" =~ ^[^/]+/[^/]+$ ]]; then
          echo "::error::repository must be owner/repo, got: ${REPOSITORY}"
          exit 1
        fi

        if [ -z "${INPUT_TOKEN}" ]; then
          echo "::error::token is required"
          exit 1
        fi

        if [ -z "${INPUT_TITLE}" ]; then
          echo "::error::title is required"
          exit 1
        fi

        if [ -z "${HEAD}" ]; then
          echo "::error::head is required"
          exit 1
        fi

        API_BASE="${GITEA_URL}/api/v1/repos/${REPOSITORY}"
        AUTH_HEADER="Authorization: token ${INPUT_TOKEN}"

        echo "::notice::Creating pull request ${REPOSITORY}: ${HEAD} -> ${BASE}"

        PAYLOAD="$(
          jq -n \
            --arg title "${INPUT_TITLE}" \
            --arg body "${INPUT_BODY}" \
            --arg head "${HEAD}" \
            --arg base "${BASE}" \
            '{title: $title, body: $body, head: $head, base: $base}'
        )"

        HTTP_CODE="$(
          curl \
            --silent \
            --show-error \
            --output /tmp/gitea-pr-response \
            --write-out "%{http_code}" \
            -X POST \
            -H "${AUTH_HEADER}" \
            -H "Content-Type: application/json" \
            --data "${PAYLOAD}" \
            "${API_BASE}/pulls"
        )"

        echo "::group::Gitea pull request API response"
        echo "HTTP ${HTTP_CODE}"
        cat /tmp/gitea-pr-response
        echo
        echo "::endgroup::"

        write_outputs() {
          local response_file="$1"
          local number url html_url
          number="$(jq -r '.number // empty' "${response_file}")"
          url="$(jq -r '.url // empty' "${response_file}")"
          html_url="$(jq -r '.html_url // empty' "${response_file}")"

          if [ -z "${number}" ]; then
            echo "::error::Could not parse pull request number from API response"
            exit 1
          fi

          echo "number=${number}" >> "${GITHUB_OUTPUT}"
          echo "url=${url}" >> "${GITHUB_OUTPUT}"
          echo "html_url=${html_url}" >> "${GITHUB_OUTPUT}"
          echo "::notice::Pull request #${number}: ${html_url}"
        }

        case "${HTTP_CODE}" in
          201)
            write_outputs /tmp/gitea-pr-response
            ;;
          *)
            if [ "${ALLOW_EXISTING}" = "true" ]; then
              echo "::notice::Create failed with HTTP ${HTTP_CODE}. Checking for an existing open pull request."

              EXISTING_CODE="$(
                curl \
                  --silent \
                  --show-error \
                  --output /tmp/gitea-pr-existing \
                  --write-out "%{http_code}" \
                  -H "${AUTH_HEADER}" \
                  "${API_BASE}/pulls?state=open&head=${HEAD}"
              )"

              if [ "${EXISTING_CODE}" -eq 200 ]; then
                MATCH="$(
                  jq \
                    --arg head "${HEAD}" \
                    --arg base "${BASE}" \
                    '[.[] | select((.head.ref == $head or .head.label == $head) and .base.ref == $base)] | .[0] // empty' \
                    /tmp/gitea-pr-existing
                )"

                if [ -n "${MATCH}" ]; then
                  echo "${MATCH}" > /tmp/gitea-pr-response
                  echo "::notice::Open pull request already exists. Reusing it."
                  write_outputs /tmp/gitea-pr-response
                  exit 0
                fi
              fi
            fi

            echo "::error::Failed to create pull request with HTTP ${HTTP_CODE}"
            exit 1
            ;;
        esac