Chained multiple pipeline based on 'post' jenkins block - jenkins

Question

I'm beginner to Jenkins. I have code pipeline structure like this
Repo1 -> Repo2 -> Repo3 -> Deploy
I already created such hierarchy via GUI but I want to create it via pipeline as code.I want to create chain of pipelines where I clone different repos and perform tests on it and then continue to another repo based on current pipeline post result.
This is my jenkinsfile - (psuedo code like as it gives me error to build)
pipeline {
agent any
stages {
stage('Build Repo1') {
steps {
sh 'echo "repo1 build!"'
}
}
stage('Test Repo1') {
steps {
sh 'echo "repo success!"'
}
}
}
post {
success {
pipeline {
agent any
stages {
stage('Build Repo2') {
steps {
sh 'echo "build repo2!"'
}
}
stage('Test Repo2') {
steps {
sh 'echo "test repo2!"'
}
}
}
post {
success {
# continue to generate pipeline for repo3
echo 'This will always run'
}
failure {
echo 'This will run only if failed'
}
}
}
}
failure {
echo 'This will run only if failed'
}
unstable {
echo 'This will run only if the run was marked as unstable'
}
changed {
echo 'This will run only if the state of the Pipeline has changed'
echo 'For example, if the Pipeline was previously failing but is now successful'
}
}
}
Please help!