package app

import (
	"errors"
	"fmt"
)

// OperationPhase describes coordination state independently of any terminal UI.
type OperationPhase uint8

const (
	OperationRunning OperationPhase = iota + 1
	OperationAwaitingConfirmation
	OperationSucceeded
	OperationFailed
	OperationBlocked
)

// StatusKind gives presentation layers semantics without requiring them to
// inspect user-facing status text.
type StatusKind uint8

const (
	StatusProgress StatusKind = iota + 1
	StatusSuccess
	StatusError
	StatusBlocked
	StatusConfirmation
)

// OperationStatus is the current concise status plus optional expandable
// detail. TargetID relates a result to the Target it can explicitly resolve.
type OperationStatus struct {
	Kind     StatusKind
	Summary  string
	Detail   string
	TargetID string
}

// Confirmation is a structured, safe-default decision. Presentation layers
// render these fields but never infer confirmation state from their wording.
type Confirmation struct {
	Title        string
	Summary      string
	Details      []string
	ConfirmLabel string
	CancelLabel  string
	HighImpact   bool
}

// TargetProgressPhase describes one Target's part in an operation stream.
type TargetProgressPhase uint8

const (
	TargetProgressRunning TargetProgressPhase = iota + 1
	TargetProgressSucceeded
	TargetProgressFailed
)

// OperationUpdate is the common progressive contract used by interactive
// detection, Target mutation, and Active Profile transition operations.
type OperationUpdate struct {
	Snapshot            Snapshot
	Phase               OperationPhase
	Status              OperationStatus
	Progress            []TargetProgress
	Confirmation        *Confirmation
	FirstFailedTargetID string
	Err                 error
}

// OperationStream exposes the useful initial frame synchronously and all
// subsequent structured changes through Updates. Updates closes after a
// terminal phase.
type OperationStream struct {
	Snapshot Snapshot
	Updates  <-chan OperationUpdate
}

// InteractiveModule is the presentation-independent Application seam used by
// the TUI. Module.Dispatch remains available for synchronous callers.
type InteractiveModule interface {
	Module
	StartOperation(Intent) OperationStream
}

// StartOperation rejects overlap instead of queuing hidden interactive work.
// Synchronous Dispatch callers retain the established serialized behavior.
func (a *Application) StartOperation(intent Intent) OperationStream {
	a.interactiveMu.Lock()
	if a.interactiveOperation {
		a.interactiveMu.Unlock()
		updates := make(chan OperationUpdate, 1)
		updates <- OperationUpdate{
			Snapshot: a.Snapshot(),
			Phase:    OperationBlocked,
			Status: OperationStatus{Kind: StatusBlocked,
				Summary: "Another system operation is already in progress",
				Detail:  "Wait for the current operation to finish before starting another modification."},
		}
		close(updates)
		return OperationStream{Snapshot: a.Snapshot(), Updates: updates}
	}
	a.interactiveOperation = true
	a.interactiveMu.Unlock()

	if intent.Kind == RefreshTargets {
		return a.startDetectionOperation()
	}

	initial := a.Snapshot()
	updates := make(chan OperationUpdate, 2*len(a.targets)+2)
	go func() {
		defer close(updates)
		defer a.finishInteractiveOperation()
		final := a.dispatch(intent, func(result Result) {
			updates <- operationUpdate(result, false)
		})
		updates <- operationUpdate(final, true)
	}()
	return OperationStream{Snapshot: initial, Updates: updates}
}

func (a *Application) startDetectionOperation() OperationStream {
	initial, detection := a.BeginTargetDetection()
	updates := make(chan OperationUpdate, len(a.targets)+1)
	go func() {
		defer close(updates)
		defer a.finishInteractiveOperation()
		var failures []error
		firstFailed := ""
		for item := range detection {
			if item.Complete {
				update := OperationUpdate{
					Snapshot: item.Snapshot,
					Phase:    OperationSucceeded,
					Status:   OperationStatus{Kind: StatusSuccess, Summary: "Target availability and state checks completed"},
				}
				if len(failures) > 0 {
					update.Phase = OperationFailed
					update.Err = errors.Join(failures...)
					update.FirstFailedTargetID = firstFailed
					update.Status = OperationStatus{Kind: StatusError, Summary: "Some Target checks failed", Detail: update.Err.Error(), TargetID: firstFailed}
				}
				updates <- update
				continue
			}
			targetSnapshot, name := targetByID(item.Snapshot, item.TargetID)
			progress := TargetProgress{TargetID: item.TargetID, State: targetSnapshot.State, Evidence: targetSnapshot.Evidence, Phase: TargetProgressSucceeded}
			status := OperationStatus{Kind: StatusProgress, Summary: "Checked " + name + " Target", TargetID: item.TargetID}
			if targetSnapshot.DetectionPhase == TargetDetectionFailed {
				progress.Phase = TargetProgressFailed
				progress.Err = targetSnapshot.DetectionErr
				status = OperationStatus{Kind: StatusError, Summary: "Could not check " + name + " Target", TargetID: item.TargetID}
				if targetSnapshot.DetectionErr != nil {
					status.Detail = targetSnapshot.DetectionErr.Error()
					failures = append(failures, fmt.Errorf("%s Target: %w", name, targetSnapshot.DetectionErr))
				}
				if firstFailed == "" {
					firstFailed = item.TargetID
				}
			}
			updates <- OperationUpdate{Snapshot: item.Snapshot, Phase: OperationRunning, Status: status, Progress: []TargetProgress{progress}, Err: progress.Err}
		}
	}()
	return OperationStream{Snapshot: initial, Updates: updates}
}

func (a *Application) finishInteractiveOperation() {
	a.interactiveMu.Lock()
	a.interactiveOperation = false
	a.interactiveMu.Unlock()
}

func targetByID(snapshot Snapshot, id string) (TargetSnapshot, string) {
	for _, item := range snapshot.Targets {
		if item.ID == id {
			name := item.Description.Name
			if name == "" {
				name = id
			}
			return item, name
		}
	}
	return TargetSnapshot{ID: id}, id
}

func operationUpdate(result Result, terminal bool) OperationUpdate {
	update := OperationUpdate{
		Snapshot:            result.Snapshot,
		Phase:               OperationRunning,
		Status:              result.Status,
		Progress:            result.Progress,
		Confirmation:        result.ConfirmationRequest,
		FirstFailedTargetID: result.FirstFailedTargetID,
		Err:                 result.Err,
	}
	if result.ConfirmationRequest != nil {
		update.Phase = OperationAwaitingConfirmation
		if update.Status.Kind == 0 {
			update.Status = OperationStatus{Kind: StatusConfirmation, Summary: result.ConfirmationRequest.Title, Detail: result.ConfirmationRequest.Summary}
		}
		return update
	}
	if update.Status.Kind == 0 {
		switch {
		case result.Err != nil:
			update.Status = OperationStatus{Kind: StatusError, Summary: "Operation failed", Detail: result.Err.Error()}
		case result.Notice != "":
			update.Status = OperationStatus{Kind: StatusSuccess, Summary: result.Notice}
		}
	}
	if !terminal {
		return update
	}
	if result.Err != nil {
		update.Phase = OperationFailed
		if update.Status.Kind != StatusError {
			update.Status = OperationStatus{Kind: StatusError, Summary: "Operation failed", Detail: result.Err.Error(), TargetID: update.Status.TargetID}
		}
	} else {
		update.Phase = OperationSucceeded
		if update.Status.Kind == StatusProgress || update.Status.Kind == 0 {
			update.Status.Kind = StatusSuccess
		}
	}
	return update
}