package views

import (
	"bytes"
	"fmt"
	"sort"
	"strings"

	"github.com/hashicorp/terraform/addrs"
	"github.com/hashicorp/terraform/command/arguments"
	"github.com/hashicorp/terraform/command/format"
	"github.com/hashicorp/terraform/plans"
	"github.com/hashicorp/terraform/states"
	"github.com/hashicorp/terraform/terraform"
	"github.com/hashicorp/terraform/tfdiags"
)

// The Plan view is used for the plan command.
type Plan interface {
	Operation() Operation
	Hooks() []terraform.Hook

	Diagnostics(diags tfdiags.Diagnostics)
	HelpPrompt(string)
}

// NewPlan returns an initialized Plan implementation for the given ViewType.
func NewPlan(vt arguments.ViewType, runningInAutomation bool, view *View) Plan {
	switch vt {
	case arguments.ViewHuman:
		return &PlanHuman{
			View:         *view,
			inAutomation: runningInAutomation,
		}
	default:
		panic(fmt.Sprintf("unknown view type %v", vt))
	}
}

// The PlanHuman implementation renders human-readable text logs, suitable for
// a scrolling terminal.
type PlanHuman struct {
	View

	inAutomation bool
}

var _ Plan = (*PlanHuman)(nil)

func (v *PlanHuman) Operation() Operation {
	return NewOperation(arguments.ViewHuman, v.inAutomation, &v.View)
}

func (v *PlanHuman) Hooks() []terraform.Hook {
	return []terraform.Hook{
		NewUiHook(&v.View),
	}
}

// The plan renderer is used by the Operation view (for plan and apply
// commands) and the Show view (for the show command).
func renderPlan(plan *plans.Plan, baseState *states.State, schemas *terraform.Schemas, view *View) {
	counts := map[plans.Action]int{}
	var rChanges []*plans.ResourceInstanceChangeSrc
	for _, change := range plan.Changes.Resources {
		if change.Action == plans.Delete && change.Addr.Resource.Resource.Mode == addrs.DataResourceMode {
			// Avoid rendering data sources on deletion
			continue
		}

		rChanges = append(rChanges, change)
		counts[change.Action]++
	}

	headerBuf := &bytes.Buffer{}
	fmt.Fprintf(headerBuf, "\n%s\n", strings.TrimSpace(format.WordWrap(planHeaderIntro, view.outputColumns())))
	if counts[plans.Create] > 0 {
		fmt.Fprintf(headerBuf, "%s create\n", format.DiffActionSymbol(plans.Create))
	}
	if counts[plans.Update] > 0 {
		fmt.Fprintf(headerBuf, "%s update in-place\n", format.DiffActionSymbol(plans.Update))
	}
	if counts[plans.Delete] > 0 {
		fmt.Fprintf(headerBuf, "%s destroy\n", format.DiffActionSymbol(plans.Delete))
	}
	if counts[plans.DeleteThenCreate] > 0 {
		fmt.Fprintf(headerBuf, "%s destroy and then create replacement\n", format.DiffActionSymbol(plans.DeleteThenCreate))
	}
	if counts[plans.CreateThenDelete] > 0 {
		fmt.Fprintf(headerBuf, "%s create replacement and then destroy\n", format.DiffActionSymbol(plans.CreateThenDelete))
	}
	if counts[plans.Read] > 0 {
		fmt.Fprintf(headerBuf, "%s read (data resources)\n", format.DiffActionSymbol(plans.Read))
	}

	view.streams.Println(view.colorize.Color(headerBuf.String()))

	view.streams.Printf("Terraform will perform the following actions:\n\n")

	// Note: we're modifying the backing slice of this plan object in-place
	// here. The ordering of resource changes in a plan is not significant,
	// but we can only do this safely here because we can assume that nobody
	// is concurrently modifying our changes while we're trying to print it.
	sort.Slice(rChanges, func(i, j int) bool {
		iA := rChanges[i].Addr
		jA := rChanges[j].Addr
		if iA.String() == jA.String() {
			return rChanges[i].DeposedKey < rChanges[j].DeposedKey
		}
		return iA.Less(jA)
	})

	for _, rcs := range rChanges {
		if rcs.Action == plans.NoOp {
			continue
		}

		providerSchema := schemas.ProviderSchema(rcs.ProviderAddr.Provider)
		if providerSchema == nil {
			// Should never happen
			view.streams.Printf("(schema missing for %s)\n\n", rcs.ProviderAddr)
			continue
		}
		rSchema, _ := providerSchema.SchemaForResourceAddr(rcs.Addr.Resource.Resource)
		if rSchema == nil {
			// Should never happen
			view.streams.Printf("(schema missing for %s)\n\n", rcs.Addr)
			continue
		}

		// check if the change is due to a tainted resource
		tainted := false
		if !baseState.Empty() {
			if is := baseState.ResourceInstance(rcs.Addr); is != nil {
				if obj := is.GetGeneration(rcs.DeposedKey.Generation()); obj != nil {
					tainted = obj.Status == states.ObjectTainted
				}
			}
		}

		view.streams.Println(format.ResourceChange(
			rcs,
			tainted,
			rSchema,
			view.colorize,
		))
	}

	// stats is similar to counts above, but:
	// - it considers only resource changes
	// - it simplifies "replace" into both a create and a delete
	stats := map[plans.Action]int{}
	for _, change := range rChanges {
		switch change.Action {
		case plans.CreateThenDelete, plans.DeleteThenCreate:
			stats[plans.Create]++
			stats[plans.Delete]++
		default:
			stats[change.Action]++
		}
	}
	view.streams.Printf(
		view.colorize.Color("[reset][bold]Plan:[reset] %d to add, %d to change, %d to destroy.\n"),
		stats[plans.Create], stats[plans.Update], stats[plans.Delete],
	)

	// If there is at least one planned change to the root module outputs
	// then we'll render a summary of those too.
	var changedRootModuleOutputs []*plans.OutputChangeSrc
	for _, output := range plan.Changes.Outputs {
		if !output.Addr.Module.IsRoot() {
			continue
		}
		if output.ChangeSrc.Action == plans.NoOp {
			continue
		}
		changedRootModuleOutputs = append(changedRootModuleOutputs, output)
	}
	if len(changedRootModuleOutputs) > 0 {
		view.streams.Println(
			view.colorize.Color("[reset]\n[bold]Changes to Outputs:[reset]") +
				format.OutputChanges(changedRootModuleOutputs, view.colorize),
		)
	}
}

const planHeaderIntro = `
Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols:
`