package projectinstance

import (
	"context"
	"crypto/rand"
	"encoding/hex"
	"fmt"
	"time"

	"chat-agent-system/internal/projectworkflow"
	"chat-agent-system/internal/workflowdef"
)

// VersionResolver 解析已发布工作流版本。
type VersionResolver interface {
	GetDefinitionByKey(ctx context.Context, key string) (*workflowdef.Definition, error)
	GetVersion(ctx context.Context, workflowID int64, version int) (*workflowdef.Version, error)
	ListDefinitions(ctx context.Context) ([]workflowdef.Definition, error)
}

// Service 项目工作流实例与激活领域服务。
type Service struct {
	store    Store
	wfStore  VersionResolver
	projects projectworkflow.Store
	docs     DocumentReadinessChecker
}

func NewService(store Store, wfStore VersionResolver, projects projectworkflow.Store, docs DocumentReadinessChecker) *Service {
	return &Service{store: store, wfStore: wfStore, projects: projects, docs: docs}
}

func (s *Service) Available() bool {
	return s != nil && s.store != nil && s.wfStore != nil
}

func (s *Service) HasLiveInstance(ctx context.Context, projectID int64) (bool, error) {
	if !s.Available() {
		return false, nil
	}
	return s.store.HasLiveInstance(ctx, projectID)
}

func (s *Service) GetSettings(ctx context.Context, projectID int64, userID int64, isCreator bool) (*ProjectSettings, error) {
	if projectID <= 0 {
		return nil, ErrProjectNotFound
	}
	lifecycle, activeKey, selVer, planRev, err := s.store.GetProjectMeta(ctx, projectID)
	if err != nil {
		return nil, err
	}

	settings := &ProjectSettings{
		ProjectID:                projectID,
		LifecycleStatus:          lifecycle,
		ActiveWorkflowKey:        activeKey,
		WorkflowSelectionVersion: selVer,
		WorkflowPlanRevision:     planRev,
		CanEditPlan:              isCreator && lifecycle == LifecyclePlanning,
		CanActivate:              isCreator && lifecycle == LifecyclePlanning,
	}

	planInst, err := s.store.GetPlanningInstance(ctx, projectID)
	if err != nil {
		return nil, err
	}
	if planInst != nil {
		settings.PlanningInstance = planInst
		settings.Plan = &planInst.ConfigSnapshot
	}

	liveInst, err := s.store.GetLiveInstance(ctx, projectID)
	if err != nil {
		return nil, err
	}
	if liveInst != nil {
		settings.LiveInstance = liveInst
		settings.CanEditPlan = false
		settings.CanActivate = false
		if detail, detailErr := s.store.GetInstanceByID(ctx, liveInst.ID); detailErr == nil && detail != nil {
			settings.ActiveStageKey = detail.ActiveStageKey
			if detail.ActiveStageKey != "" && s.docs != nil {
				if version, verErr := s.resolvePublishedVersion(ctx, liveInst.ConfigSnapshot); verErr == nil {
					if stagePlan := findStagePlan(liveInst.ConfigSnapshot, detail.ActiveStageKey); stagePlan != nil {
						docStates, _ := s.docs.TaskApprovalStates(ctx, projectID)
						ready, _, _ := evaluateStageReadiness(*stagePlan, findStageDef(version.Definition, detail.ActiveStageKey), docStates)
						settings.StageAdvanceReady = ready
					}
				}
			}
		}
	}

	if s.wfStore != nil {
		defs, listErr := s.wfStore.ListDefinitions(ctx)
		if listErr == nil {
			for _, d := range defs {
				if d.LatestPublishedVersion <= 0 || !workflowdef.IsOfficialWorkflowKey(d.Key) {
					continue
				}
				ver, verErr := s.wfStore.GetVersion(ctx, d.ID, d.LatestPublishedVersion)
				if verErr != nil || ver == nil {
					continue
				}
				name := d.Name
				if name == "" || name == d.Key {
					name = workflowdef.OfficialWorkflowName(d.Key)
				}
				settings.PublishedWorkflows = append(settings.PublishedWorkflows, PublishedOption{
					DefinitionKey:   d.Key,
					DefinitionName:  name,
					LatestVersion:   d.LatestPublishedVersion,
					WorkflowVersion: ver.ID,
					ProductDomain:   d.ProductDomain,
				})
			}
		}
	}
	_ = userID
	return settings, nil
}

func (s *Service) SaveWorkflowPlan(ctx context.Context, projectID int64, userID int64, isCreator bool, in SavePlanInput) (*ProjectSettings, error) {
	if !isCreator {
		return nil, ErrForbiddenNotCreator
	}
	lifecycle, _, selVer, planRev, err := s.store.GetProjectMeta(ctx, projectID)
	if err != nil {
		return nil, err
	}
	if lifecycle != LifecyclePlanning {
		return nil, ErrPlanFrozen
	}
	live, err := s.store.HasLiveInstance(ctx, projectID)
	if err != nil {
		return nil, err
	}
	if live {
		return nil, ErrWorkflowAlreadyActive
	}
	if in.ExpectedSelectionVersion > 0 && in.ExpectedSelectionVersion != selVer {
		return nil, ErrConcurrentConflict
	}
	if in.ExpectedPlanRevision != planRev {
		return nil, ErrPlanRevisionConflict
	}

	version, err := s.resolvePublishedVersion(ctx, in.Plan)
	if err != nil {
		return nil, err
	}
	validation := validatePlan(in.Plan, version)
	if !validation.Valid {
		return nil, newValidationError(validation)
	}

	in.Plan.WorkflowVersionID = version.ID
	applyDefinitionLabels(&in.Plan, version)
	planHash, err := computePlanHash(in.Plan)
	if err != nil {
		return nil, err
	}

	inst := &WorkflowInstance{
		ProjectID:         projectID,
		WorkflowVersionID: version.ID,
		Status:            InstancePlanning,
		ConfigRevision:    planRev + 1,
		PlanHash:          planHash,
		ConfigSnapshot:    in.Plan,
		CreatedBy:         &userID,
	}
	if _, err := s.store.UpsertPlanningInstance(ctx, inst); err != nil {
		return nil, err
	}
	if _, err := s.store.BumpPlanRevision(ctx, projectID, planRev); err != nil {
		return nil, err
	}
	return s.GetSettings(ctx, projectID, userID, isCreator)
}

func (s *Service) ActivationPreview(ctx context.Context, projectID int64, userID int64, isCreator bool) (*ActivationPreview, error) {
	if !isCreator {
		return nil, ErrForbiddenNotCreator
	}
	lifecycle, _, selVer, planRev, err := s.store.GetProjectMeta(ctx, projectID)
	if err != nil {
		return nil, err
	}
	if lifecycle != LifecyclePlanning {
		return nil, ErrPlanFrozen
	}
	planInst, err := s.store.GetPlanningInstance(ctx, projectID)
	if err != nil {
		return nil, err
	}
	if planInst == nil || planInst.PlanHash == "" {
		return nil, fmt.Errorf("%w: no saved plan", ErrInvalidPlan)
	}

	version, err := s.resolvePublishedVersion(ctx, planInst.ConfigSnapshot)
	if err != nil {
		return nil, err
	}
	validation := validateActivationPlan(planInst.ConfigSnapshot, version)
	if !validation.Valid {
		return nil, newValidationError(validation)
	}

	token, err := randomToken(24)
	if err != nil {
		return nil, err
	}
	expiresAt := time.Now().Add(15 * time.Minute)
	if err := s.store.SaveActivationToken(ctx, token, projectID, planInst.PlanHash, selVer, planInst.ConfigSnapshot, userID, expiresAt); err != nil {
		return nil, err
	}

	return &ActivationPreview{
		ConfirmationToken:      token,
		PlanHash:               planInst.PlanHash,
		ExpectedProjectVersion: selVer,
		ExpectedPlanRevision:   planRev,
		Summary:                previewSummary(planInst.ConfigSnapshot, version),
		Validation:             validation,
		ExpiresAt:              expiresAt,
	}, nil
}

func (s *Service) Activate(ctx context.Context, projectID int64, userID int64, isCreator bool, in ActivateInput) (*ActivateResult, error) {
	if !isCreator {
		return nil, ErrForbiddenNotCreator
	}
	lifecycle, _, selVer, planRev, err := s.store.GetProjectMeta(ctx, projectID)
	if err != nil {
		return nil, err
	}
	if lifecycle != LifecyclePlanning {
		return nil, ErrPlanFrozen
	}
	if in.ExpectedProjectVersion != selVer {
		return nil, ErrConcurrentConflict
	}
	if in.ExpectedPlanRevision != planRev {
		return nil, ErrPlanRevisionConflict
	}

	planInst, err := s.store.GetPlanningInstance(ctx, projectID)
	if err != nil {
		return nil, err
	}
	if planInst == nil {
		return nil, fmt.Errorf("%w: no saved plan", ErrInvalidPlan)
	}

	consumed, err := s.store.ConsumeActivationToken(ctx, in.ConfirmationToken, projectID, planInst.PlanHash)
	if err != nil {
		return nil, err
	}
	currentHash, err := computePlanHash(*consumed)
	if err != nil {
		return nil, err
	}
	if currentHash != planInst.PlanHash {
		return nil, ErrPlanChangedReconfirm
	}

	version, err := s.resolvePublishedVersion(ctx, planInst.ConfigSnapshot)
	if err != nil {
		return nil, err
	}
	validation := validateActivationPlan(planInst.ConfigSnapshot, version)
	if !validation.Valid {
		return nil, ErrValidationFailed
	}

	activated, err := s.store.ActivateInstance(ctx, projectID, planInst, version, selVer, userID)
	if err != nil {
		return nil, err
	}

	return &ActivateResult{
		ProjectID:         projectID,
		LifecycleStatus:   LifecycleActive,
		ActiveWorkflowKey: version.WorkflowKey,
		Instance:          *activated,
	}, nil
}

// GetLiveInstanceDetail 返回 live 实例详情与已发布版本定义（运行时编排入口）。
func (s *Service) GetLiveInstanceDetail(ctx context.Context, projectID int64) (*InstanceDetail, *workflowdef.Version, error) {
	if s == nil || s.store == nil {
		return nil, nil, ErrNotAvailable
	}
	live, err := s.store.GetLiveInstance(ctx, projectID)
	if err != nil || live == nil {
		return nil, nil, fmt.Errorf("live instance not found")
	}
	detail, err := s.store.GetInstanceByID(ctx, live.ID)
	if err != nil {
		return nil, nil, err
	}
	version, err := s.resolvePublishedVersion(ctx, live.ConfigSnapshot)
	if err != nil {
		return nil, nil, err
	}
	return detail, version, nil
}

func (s *Service) BuildDefaultPlan(ctx context.Context, workflowKey string, versionNum int) (*WorkflowPlan, error) {
	if s.wfStore == nil {
		return nil, ErrNotAvailable
	}
	if !workflowdef.IsOfficialWorkflowKey(workflowKey) {
		return nil, ErrWorkflowVersionNotFound
	}
	def, err := s.wfStore.GetDefinitionByKey(ctx, workflowKey)
	if err != nil {
		return nil, ErrWorkflowVersionNotFound
	}
	verNum := versionNum
	if verNum <= 0 {
		verNum = def.LatestPublishedVersion
	}
	version, err := s.wfStore.GetVersion(ctx, def.ID, verNum)
	if err != nil {
		return nil, ErrWorkflowVersionNotFound
	}
	plan := buildDefaultPlan(version)
	if plan.WorkflowDefinitionKey == "" {
		plan.WorkflowDefinitionKey = def.Key
	}
	return &plan, nil
}

func (s *Service) resolvePublishedVersion(ctx context.Context, plan WorkflowPlan) (*workflowdef.Version, error) {
	if s.wfStore == nil {
		return nil, ErrNotAvailable
	}
	def, err := s.wfStore.GetDefinitionByKey(ctx, plan.WorkflowDefinitionKey)
	if err != nil {
		return nil, ErrWorkflowVersionNotFound
	}
	verNum := plan.WorkflowVersion
	if verNum <= 0 {
		verNum = def.LatestPublishedVersion
	}
	version, err := s.wfStore.GetVersion(ctx, def.ID, verNum)
	if err != nil {
		return nil, ErrWorkflowVersionNotFound
	}
	version.WorkflowKey = def.Key
	version.WorkflowName = def.Name
	return version, nil
}

func randomToken(n int) (string, error) {
	b := make([]byte, n)
	if _, err := rand.Read(b); err != nil {
		return "", err
	}
	return hex.EncodeToString(b), nil
}