// Copyright 2016-2017, Pulumi Corporation.  All rights reserved.

package cmd

import (
	"github.com/spf13/cobra"

	"github.com/pulumi/pulumi/pkg/engine"
	"github.com/pulumi/pulumi/pkg/resource/config"
	"github.com/pulumi/pulumi/pkg/util/cmdutil"
)

func newPreviewCmd() *cobra.Command {
	var analyzers []string
	var debug bool
	var stack string
	var parallel int
	var showConfig bool
	var showReplacementSteps bool
	var showSames bool
	var summary bool
	var cmd = &cobra.Command{
		Use:        "preview",
		SuggestFor: []string{"plan"},
		Short:      "Show a preview of updates to an stack's resources",
		Long: "Show a preview of updates an stack's resources\n" +
			"\n" +
			"This command displays a preview of the updates to an existing stack whose state is\n" +
			"represented by an existing snapshot file. The new desired state is computed by compiling\n" +
			"and evaluating an executable package, and extracting all resource allocations from its\n" +
			"resulting object graph. These allocations are then compared against the existing state to\n" +
			"determine what operations must take place to achieve the desired state. No changes to the\n" +
			"stack will actually take place.\n" +
			"\n" +
			"The package to execute is loaded from the current directory. Use the `-C` or `--cwd` flag to\n" +
			"use a different directory.",
		Run: cmdutil.RunFunc(func(cmd *cobra.Command, args []string) error {
			stackName, err := explicitOrCurrent(stack)
			if err != nil {
				return err
			}

			cfg, err := getConfiguration(stackName)
			if err != nil {
				return err
			}

			var decrypter config.ValueDecrypter = panicCrypter{}

			if hasSecureValue(cfg) {
				decrypter, err = getSymmetricCrypter()
				if err != nil {
					return err
				}
			}

			localProvider := localStackProvider{decrypter: decrypter}
			pulumiEngine := engine.Engine{Targets: localProvider, Snapshots: localProvider}

			events := make(chan engine.Event)
			done := make(chan bool)

			go displayEvents(events, done, debug)

			if err = pulumiEngine.Preview(stackName, events, engine.PreviewOptions{
				Analyzers:            analyzers,
				Parallel:             parallel,
				ShowConfig:           showConfig,
				ShowReplacementSteps: showReplacementSteps,
				ShowSames:            showSames,
				Summary:              summary,
			}); err != nil {
				return err
			}

			<-done
			close(events)
			close(done)
			return nil
		}),
	}

	cmd.PersistentFlags().StringSliceVar(
		&analyzers, "analyzer", []string{},
		"Run one or more analyzers as part of this preview")
	cmd.PersistentFlags().BoolVarP(
		&debug, "debug", "d", false,
		"Print detailed debugging output during resource operations")
	cmd.PersistentFlags().StringVarP(
		&stack, "stack", "s", "",
		"Choose an stack other than the currently selected one")
	cmd.PersistentFlags().IntVarP(
		&parallel, "parallel", "p", 0,
		"Allow P resource operations to run in parallel at once (<=1 for no parallelism)")
	cmd.PersistentFlags().BoolVar(
		&showConfig, "show-config", false,
		"Show configuration keys and variables")
	cmd.PersistentFlags().BoolVar(
		&showReplacementSteps, "show-replacement-steps", false,
		"Show detailed resource replacement creates and deletes instead of a single step")
	cmd.PersistentFlags().BoolVar(
		&showSames, "show-sames", false,
		"Show resources that needn't be updated because they haven't changed, alongside those that do")
	cmd.PersistentFlags().BoolVar(
		&summary, "summary", false,
		"Only display summarization of resources and operations")

	return cmd
}