Pipeline with Git

pipeline {
    agent { label 'linux' }

    options {
        timeout(time: 30, unit: 'MINUTES')
        buildDiscarder(logRotator(numToKeepStr: '20'))
        timestamps()
    }

    environment {
        APP_NAME     = 'checkout-service'
        DOCKER_CREDS = credentials('docker-registry-credentials')
        REGISTRY     = 'registry.acmecorp.com'
    }

    stages {

        stage('Checkout') {
            steps {
                checkout scm
                script {
                    // Log key Git context for this build
                    echo "Branch: ${env.BRANCH_NAME}"
                    echo "Commit: ${env.GIT_COMMIT?.take(7)}"
                    echo "Repo:   ${env.GIT_URL}"

                    // Generate a changelog from the previous build's commit to now
                    // GIT_PREVIOUS_SUCCESSFUL_COMMIT is the last commit that passed
                    if (env.GIT_PREVIOUS_SUCCESSFUL_COMMIT) {
                        def changelog = sh(
                            script: "git log --oneline ${env.GIT_PREVIOUS_SUCCESSFUL_COMMIT}..HEAD",
                            returnStdout: true
                        ).trim()
                        echo "Changes since last successful build:\n${changelog}"
                    }
                }
            }
        }

        stage('Test') {
            steps {
                sh './gradlew test'
            }
            post {
                always { junit 'build/test-results/**/*.xml' }
            }
        }

        stage('Build Docker Image') {
            // Skip image build on pure PR builds — test is enough for feedback
            // CHANGE_ID is only set when Jenkins is building a pull request
            when {
                not { expression { return env.CHANGE_ID != null } }
            }
            steps {
                sh """
                    docker login -u ${DOCKER_CREDS_USR} -p ${DOCKER_CREDS_PSW} ${REGISTRY}
                    docker build -t ${REGISTRY}/${APP_NAME}:${BUILD_NUMBER} .
                    docker push ${REGISTRY}/${APP_NAME}:${BUILD_NUMBER}
                """
            }
        }

        // Deploy to staging — only on main branch, not PRs, not feature branches
        stage('Deploy — Staging') {
            when {
                allOf {
                    branch 'main'
                    // Ensure this is not a PR build
                    not { expression { return env.CHANGE_ID != null } }
                }
            }
            steps {
                echo "Deploying ${APP_NAME} build ${BUILD_NUMBER} to staging"
                sh "./deploy.sh staging ${BUILD_NUMBER}"
            }
        }

        // Deploy to production — only on release/* branches
        // Requires manual approval from the release manager
        stage('Deploy — Production') {
            when {
                // branch pattern — matches release/v2.1, release/v3.0, etc.
                branch 'release/*'
            }
            steps {
                // Pause and wait for approval before any production change
                input(
                    message: "Deploy ${APP_NAME} ${BUILD_NUMBER} to PRODUCTION?",
                    ok: 'Deploy',
                    submitter: 'release-managers'
                )
                echo "Deploying ${APP_NAME} build ${BUILD_NUMBER} to production"
                sh "./deploy.sh production ${BUILD_NUMBER}"
            }
        }

    }

    post {
        failure {
            slackSend(
                channel: '#deployments',
                color: 'danger',
                message: "❌ *${APP_NAME}* failed on `${env.BRANCH_NAME}` — <${env.BUILD_URL}|Build #${BUILD_NUMBER}>"
            )
        }
        success {
            script {
                // Only notify on staging and production deploys — not every feature branch build
                if (env.BRANCH_NAME == 'main' || env.BRANCH_NAME?.startsWith('release/')) {
                    slackSend(
                        channel: '#deployments',
                        color: 'good',
                        message: "✅ *${APP_NAME}* deployed from `${env.BRANCH_NAME}` — <${env.BUILD_URL}|Build #${BUILD_NUMBER}>"
                    )
                }
            }
        }
        always { cleanWs() }
    }

}