#!/usr/bin/env bash
set -e
set -o noglob

# Usage:
#    curl https://get.ambientmesh.io | ENV_VAR=... sh -
#    or
#    wget -qO- https://get.ambientmesh.io | ENV_VAR=... sh -
#
# Environment Variables
#    DISTRO: The Kubernetes distribution. Supported values are: gke, k3s, k3d, minikube, microk8s, openshift, and default.
#        k3d, minikube, microk8s, and openshift are currently not able to be automatically detected but can be manually specified.
#    CONTEXT: The Kubernetes context to use. Default is the current context.
#
# Purpose:
#     The purpose of this script is to automatically detect the Kubernetes distribution to apply the correct manifest to the cluster
#     as well as apply the Gateway API CRDs.

function k() {
  kubectl --context "$CONTEXT" $@
}

function main() {
  if ! command -v kubectl > /dev/null; then
    echo "kubectl is not installed. Please install kubectl."
    exit 1
  fi

  GATEWAY_API_MANIFEST_URL="https://github.com/kubernetes-sigs/gateway-api/releases/download/v1.3.0/standard-install.yaml"
  AMBIENTMESH_HOST=${AMBIENTMESH_HOST:-"get.ambientmesh.io"}
  BASE_URL="https://${AMBIENTMESH_HOST}"

  # Allow overriding context without changing the current context.
  CONTEXT=${CONTEXT:-$(kubectl config current-context)}

  echo "* Determining Kubernetes cluster distribution..."
  cluster_version=""
  if command -v jq > /dev/null; then
    cluster_version=$(k version -o json | jq -r '.serverVersion.gitVersion')
  else
    cluster_version=$(k version -o json | grep -A 5 '"serverVersion"' | grep '"gitVersion"' | sed 's/.*"gitVersion": "\(.*\)",/\1/' | tr -d '\n')
  fi

  echo "  * Detected Kubernetes cluster version $cluster_version."
  echo ""
  
  distro=${DISTRO:-""}

  if [[ -z "$distro" ]]; then
    echo "* Determining if your Kubernetes distribution requires custom settings..."
    case "$cluster_version" in
      *gke*)
        echo "  * Using settings for Google Kubernetes Engine (GKE)."
        distro="gke"
        ;;
      *k3s*)
        echo "  * Using settings for k3s."
        distro="k3s"
        ;;
      *)
        echo "  * Using default settings."
        distro=default
        ;;
    esac
  else
    # Check if DISTRO is set to a valid value. Accepted values are: gke, k3s, minikube, microk8s, openshift, and default.
    # If not, exit with an error.
    case "$distro" in
      gke|k3s|k3d|minikube|microk8s|openshift|default)
        ;;
      *)
        echo "* Invalid value for DISTRO: $distro"
        exit 1
        ;;
    esac
  fi
  echo ""

  echo "* Installing Istio & Gateway API..."
  echo ""
  
  k create namespace istio-system || true
  k apply -f "$BASE_URL/yamls/$distro.yaml"
  k apply -f "$GATEWAY_API_MANIFEST_URL"

  echo ""
  echo "* Installation complete. Waiting for all components to be ready..."
  echo ""

  k rollout status deployment/istiod -n istio-system
  k rollout status daemonset/istio-cni-node -n istio-system
  k rollout status daemonset/ztunnel -n istio-system

  echo ""
  echo "* Ambient mesh is now installed and ready!"
  echo ""

  k get pods -n istio-system
}

main