package main

import (
	"fmt"
	"os"
	"os/exec"
	"strings"

	"github.com/blang/semver"
	"github.com/spf13/cobra"
)

var checkCmd = &cobra.Command{
	Use:   "check",
	Short: "Check requirements",
	Long: `
The check command will perform a series of checks to validate that
the local environment is configured correctly.`,
	Example: `  check --pre`,
	RunE:    runCheckCmd,
}

var (
	checkPre bool
)

func init() {
	checkCmd.Flags().BoolVarP(&checkPre, "pre", "", false,
		"only run pre-installation checks")

	rootCmd.AddCommand(checkCmd)
}

func runCheckCmd(cmd *cobra.Command, args []string) error {
	if !sshCheck() {
		os.Exit(1)
	}

	if !kubectlCheck(">=1.14.0") {
		os.Exit(1)
	}

	if !kustomizeCheck(">=3.5.0") {
		os.Exit(1)
	}

	if checkPre {
		fmt.Println(`✔`, "all prerequisites checks passed")
		return nil
	}

	if !kubernetesCheck(">=1.14.0") {
		os.Exit(1)
	}

	fmt.Println(`✔`, "all checks passed")
	return nil
}

func sshCheck() bool {
	ok := true
	for _, cmd := range []string{"ssh-keygen", "ssh-keyscan"} {
		_, err := exec.LookPath(cmd)
		if err != nil {
			fmt.Println(`✗`, cmd, "not found")
			ok = false
		} else {
			fmt.Println(`✔`, cmd, "found")
		}
	}

	return ok
}

func kubectlCheck(version string) bool {
	_, err := exec.LookPath("kubectl")
	if err != nil {
		fmt.Println(`✗`, "kubectl not found")
		return false
	}

	output, err := execCommand("kubectl version --client --short | awk '{ print $3 }'")
	if err != nil {
		fmt.Println(`✗`, "kubectl version can't be determined")
		return false
	}

	v, err := semver.ParseTolerant(output)
	if err != nil {
		fmt.Println(`✗`, "kubectl version can't be parsed")
		return false
	}

	rng, _ := semver.ParseRange(version)
	if !rng(v) {
		fmt.Println(`✗`, "kubectl version must be", version)
		return false
	}

	fmt.Println(`✔`, "kubectl", v.String())
	return true
}

func kustomizeCheck(version string) bool {
	_, err := exec.LookPath("kustomize")
	if err != nil {
		fmt.Println(`✗`, "kustomize not found")
		return false
	}

	output, err := execCommand("kustomize version --short | awk '{ print $1 }' | cut -c2-")
	if err != nil {
		fmt.Println(`✗`, "kustomize version can't be determined")
		return false
	}

	if strings.Contains(output, "kustomize/") {
		output, err = execCommand("kustomize version --short | awk '{ print $1 }' | cut -c12-")
		if err != nil {
			fmt.Println(`✗`, "kustomize version can't be determined")
			return false
		}
	}

	v, err := semver.ParseTolerant(output)
	if err != nil {
		fmt.Println(`✗`, "kustomize version can't be parsed")
		return false
	}

	rng, _ := semver.ParseRange(version)
	if !rng(v) {
		fmt.Println(`✗`, "kustomize version must be", version)
		return false
	}

	fmt.Println(`✔`, "kustomize", v.String())
	return true
}

func kubernetesCheck(version string) bool {
	client, err := kubernetesClient()
	if err != nil {
		fmt.Println(`✗`, "kubernetes client initialization failed", err.Error())
		return false
	}

	ver, err := client.Discovery().ServerVersion()
	if err != nil {
		fmt.Println(`✗`, "kubernetes API call failed", err.Error())
		return false
	}

	v, err := semver.ParseTolerant(ver.String())
	if err != nil {
		fmt.Println(`✗`, "kubernetes version can't be determined")
		return false
	}

	rng, _ := semver.ParseRange(version)
	if !rng(v) {
		fmt.Println(`✗`, "kubernetes version must be", version)
		return false
	}

	fmt.Println(`✔`, "kubernetes", v.String())
	return true
}