package service

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"time"

	"github.com/gochat/gochat/internal/model"
	"github.com/gochat/gochat/internal/repository"
	applogger "github.com/gochat/gochat/pkg/logger"
	pkgvalidator "github.com/gochat/gochat/pkg/validator"
)

// AccountService implements business logic for Account operations.
// Reference: Chatwoot app/controllers/api/v1/accounts_controller.rb
type AccountService struct {
	repo *repository.AccountRepo
}

const chatwootMaxLimit = 100000

// NewAccountService creates a new Account service.
func NewAccountService(repo *repository.AccountRepo) *AccountService {
	return &AccountService{repo: repo}
}

// ListByUser retrieves all accounts accessible by a user.
func (s *AccountService) ListByUser(ctx context.Context, userID uint, offset, limit int) ([]model.Account, int64, error) {
	return s.repo.FindByUser(ctx, userID, offset, limit)
}

// GetByID retrieves a single account.
func (s *AccountService) GetByID(ctx context.Context, id uint) (*model.Account, error) {
	return s.repo.FindByID(ctx, id)
}

// GetByUserAndID retrieves an account only when the user belongs to it.
func (s *AccountService) GetByUserAndID(ctx context.Context, userID, accountID uint) (*model.Account, error) {
	return s.repo.FindByUserAndID(ctx, userID, accountID)
}

// CreateAccountRequest is the DTO for creating an account.
type CreateAccountRequest struct {
	Name        string `json:"name,omitempty" validate:"omitempty,min=2"`
	AccountName string `json:"account_name,omitempty" validate:"omitempty,min=2"`
	Locale      string `json:"locale,omitempty" validate:"omitempty,len=2"`
	Domain      string `json:"domain,omitempty" validate:"omitempty,min=3"`
}

// Create creates a new account and assigns the creator as administrator.
func (s *AccountService) Create(ctx context.Context, userID uint, req CreateAccountRequest) (*model.Account, error) {
	if req.Name == "" {
		req.Name = req.AccountName
	}
	if err := pkgvalidator.ValidateStruct(req); err != nil {
		return nil, err
	}
	if req.Name == "" {
		return nil, errors.New("account_name is required")
	}

	account := &model.Account{
		Name:   req.Name,
		Locale: req.Locale,
		Domain: req.Domain,
		Status: "active",
	}

	if err := s.repo.Create(ctx, account); err != nil {
		applogger.L().Errorf("Failed to create account: %v", err)
		return nil, err
	}

	// Assign creator as administrator
	if err := s.repo.AddUserToAccount(ctx, account.ID, userID, "administrator"); err != nil {
		applogger.L().Errorf("Failed to assign creator to account: %v", err)
		return nil, err
	}

	return account, nil
}

// UpdateAccountRequest is the DTO for updating an account.
type UpdateAccountRequest struct {
	Name                     string `json:"name,omitempty" validate:"omitempty,min=2"`
	Locale                   string `json:"locale,omitempty" validate:"omitempty,len=2"`
	Domain                   string `json:"domain,omitempty" validate:"omitempty,min=3"`
	SupportEmail             string `json:"support_email,omitempty"`
	FeatureFlags             string `json:"feature_flags,omitempty"`
	Status                   string `json:"status,omitempty" validate:"omitempty,oneof=active inactive"`
	AutoResolveDuration      int    `json:"auto_resolve_duration,omitempty" validate:"omitempty,gte=0"`
	AutoResolveAfter         int    `json:"auto_resolve_after,omitempty" validate:"omitempty,gte=0"`
	AutoResolveMessage       string `json:"auto_resolve_message,omitempty"`
	AutoResolveIgnoreWaiting *bool  `json:"auto_resolve_ignore_waiting,omitempty"`
	AudioTranscriptions      *bool  `json:"audio_transcriptions,omitempty"`
	AutoResolveLabel         string `json:"auto_resolve_label,omitempty"`
}

// UpdateAccountOnboardingRequest matches Chatwoot's account onboarding payload.
// Reference: Api::V1::Accounts::OnboardingsController#update.
type UpdateAccountOnboardingRequest struct {
	Name           *string `json:"name,omitempty"`
	Locale         *string `json:"locale,omitempty"`
	Industry       *string `json:"industry,omitempty"`
	CompanySize    *string `json:"company_size,omitempty"`
	Timezone       *string `json:"timezone,omitempty"`
	ReferralSource *string `json:"referral_source,omitempty"`
	UserRole       *string `json:"user_role,omitempty"`
	Website        *string `json:"website,omitempty"`
}

// Update modifies an existing account.
func (s *AccountService) Update(ctx context.Context, id uint, req UpdateAccountRequest) (*model.Account, error) {
	if err := pkgvalidator.ValidateStruct(req); err != nil {
		return nil, err
	}

	account, err := s.repo.FindByID(ctx, id)
	if err != nil {
		return nil, err
	}

	if req.Name != "" {
		account.Name = req.Name
	}
	if req.Locale != "" {
		account.Locale = req.Locale
	}
	if req.Domain != "" {
		account.Domain = req.Domain
	}
	if req.FeatureFlags != "" {
		account.FeatureFlags = req.FeatureFlags
	}
	if req.Status != "" {
		account.Status = req.Status
	}
	if req.AutoResolveAfter > 0 {
		account.AutoResolveDuration = req.AutoResolveAfter
	} else if req.AutoResolveDuration > 0 {
		account.AutoResolveDuration = req.AutoResolveDuration
	}

	if err := s.repo.Update(ctx, account); err != nil {
		return nil, err
	}
	return account, nil
}

// UpdateOnboarding updates account details and onboarding custom attributes.
func (s *AccountService) UpdateOnboarding(ctx context.Context, id uint, req UpdateAccountOnboardingRequest) (*model.Account, error) {
	account, err := s.repo.FindByID(ctx, id)
	if err != nil {
		return nil, err
	}

	attrs := account.CustomAttributesMap()
	finalize := attrs["onboarding_step"] == "account_details" || account.OnboardingStep == "account_details"

	if req.Name != nil {
		account.Name = *req.Name
	}
	if req.Locale != nil {
		account.Locale = *req.Locale
	}
	mergeStringAttribute(attrs, "industry", req.Industry)
	mergeStringAttribute(attrs, "company_size", req.CompanySize)
	mergeStringAttribute(attrs, "timezone", req.Timezone)
	mergeStringAttribute(attrs, "referral_source", req.ReferralSource)
	mergeStringAttribute(attrs, "user_role", req.UserRole)
	mergeStringAttribute(attrs, "website", req.Website)
	if req.Timezone != nil {
		account.Timezone = *req.Timezone
	}
	if finalize {
		delete(attrs, "onboarding_step")
		account.OnboardingStep = ""
	}
	if err := account.SetCustomAttributesMap(attrs); err != nil {
		return nil, err
	}

	if err := s.repo.Update(ctx, account); err != nil {
		return nil, err
	}
	return account, nil
}

func mergeStringAttribute(attrs map[string]any, key string, value *string) {
	if value != nil {
		attrs[key] = *value
	}
}

// Delete soft-deletes an account.
func (s *AccountService) Delete(ctx context.Context, id uint) error {
	if s.repo == nil {
		return errors.New("account repository is not initialized")
	}
	return s.repo.Delete(ctx, id)
}

// ListUsers retrieves all users belonging to an account.
func (s *AccountService) ListUsers(ctx context.Context, accountID uint, offset, limit int) ([]model.User, int64, error) {
	return s.repo.FindUsersByAccount(ctx, accountID, offset, limit)
}

// AddUserRequest is the DTO for adding a user to an account.
type AddUserRequest struct {
	UserID uint   `json:"user_id" validate:"required"`
	Role   string `json:"role" validate:"required,oneof=agent administrator"`
}

// AddUser adds a user to an account with a specified role.
func (s *AccountService) AddUser(ctx context.Context, accountID uint, req AddUserRequest) error {
	if err := pkgvalidator.ValidateStruct(req); err != nil {
		return err
	}
	return s.repo.AddUserToAccount(ctx, accountID, req.UserID, req.Role)
}

// RemoveUser removes a user from an account.
func (s *AccountService) RemoveUser(ctx context.Context, accountID, userID uint) error {
	if accountID == 0 || userID == 0 {
		return errors.New("account_id and user_id are required")
	}
	return s.repo.RemoveUserFromAccount(ctx, accountID, userID)
}

// UpdateAccountSettingsRequest is the DTO for updating account settings.
type UpdateAccountSettingsRequest struct {
	AutoResolveDuration int    `json:"auto_resolve_duration" validate:"gte=0"`
	Locale              string `json:"locale" validate:"omitempty,len=2"`
	ReportingTimezone   string `json:"reporting_timezone" validate:"omitempty"`
}

// UpdateSettings updates account-level settings.
func (s *AccountService) UpdateSettings(ctx context.Context, id uint, req UpdateAccountSettingsRequest) (*model.Account, error) {
	if err := pkgvalidator.ValidateStruct(req); err != nil {
		return nil, err
	}

	account, err := s.repo.FindByID(ctx, id)
	if err != nil {
		return nil, err
	}

	account.AutoResolveDuration = req.AutoResolveDuration
	if req.Locale != "" {
		account.Locale = req.Locale
	}
	if req.ReportingTimezone != "" {
		if _, err := time.LoadLocation(req.ReportingTimezone); err != nil {
			return nil, fmt.Errorf("invalid reporting_timezone")
		}
		account.ReportingTimezone = req.ReportingTimezone
	}

	if err := s.repo.Update(ctx, account); err != nil {
		return nil, err
	}
	return account, nil
}

// GetAll retrieves all accounts with pagination.
// Reference: Chatwoot platform admin listing all accounts.
func (s *AccountService) GetAll(ctx context.Context, offset, limit int) ([]model.Account, int64, error) {
	return s.repo.FindAll(ctx, offset, limit)
}

// GetAgents retrieves all agents (AccountUser records) for an account with pagination.
// Reference: Chatwoot app/controllers/api/v1/accounts/agents_controller.rb#index
func (s *AccountService) GetAgents(ctx context.Context, accountID uint, offset, limit int) ([]model.AccountUser, int64, error) {
	return s.repo.FindAgentsByAccount(ctx, accountID, offset, limit)
}

// --- Account extension operations (G8) ---
// Reference: Chatwoot accounts_controller.rb#update_active_at, #cache_keys

// UpdateActiveAt updates the active_at timestamp for a user in an account.
func (s *AccountService) UpdateActiveAt(ctx context.Context, accountID, userID uint) error {
	return s.repo.UpdateActiveAt(ctx, accountID, userID, time.Now())
}

// CacheKeys returns cache key identifiers for frontend cache invalidation.
// The keys are derived from the account's updatedAt timestamp and user membership.
// Reference: Chatwoot accounts_controller.rb#cache_keys
func (s *AccountService) CacheKeys(ctx context.Context, accountID, userID uint) (map[string]string, error) {
	if _, err := s.repo.FindByID(ctx, accountID); err != nil {
		return nil, err
	}
	if _, err := s.repo.FindAccountUserByUserAndAccount(ctx, accountID, userID); err != nil {
		return nil, err
	}
	keys := map[string]string{
		"label": "0000000000",
		"inbox": "0000000000",
		"team":  "0000000000",
	}
	return keys, nil
}

// EnterpriseLimits returns the Chatwoot enterprise account limit payload consumed
// by EnterpriseAccountAPI.getLimits in the reused dashboard frontend.
func (s *AccountService) EnterpriseLimits(ctx context.Context, accountID, userID uint) (map[string]any, error) {
	account, err := s.repo.FindByUserAndID(ctx, userID, accountID)
	if err != nil {
		return nil, err
	}

	agentsConsumed, err := s.repo.CountUsersByAccount(ctx, account.ID)
	if err != nil {
		return nil, err
	}
	documentsConsumed, err := s.repo.CountCaptainDocumentsByAccount(ctx, account.ID)
	if err != nil {
		return nil, err
	}

	limits := map[string]any{
		"conversation":    map[string]any{},
		"non_web_inboxes": map[string]any{},
		"agents": map[string]any{
			"allowed":  accountUsageLimit(account.AgentLimit),
			"consumed": agentsConsumed,
		},
		"captain": captainUsageLimits(account, documentsConsumed),
	}

	if accountDefaultCloudPlan(account) {
		conversationConsumed, err := s.repo.CountConversationsSince(ctx, account.ID, time.Now().AddDate(0, 0, -30))
		if err != nil {
			return nil, err
		}
		nonWebConsumed, err := s.repo.CountNonWebInboxes(ctx, account.ID)
		if err != nil {
			return nil, err
		}
		limits = map[string]any{
			"conversation": map[string]any{
				"allowed":  500,
				"consumed": conversationConsumed,
			},
			"non_web_inboxes": map[string]any{
				"allowed":  0,
				"consumed": nonWebConsumed,
			},
			"agents": map[string]any{
				"allowed":  2,
				"consumed": agentsConsumed,
			},
		}
	}

	return map[string]any{"id": account.ID, "limits": limits}, nil
}

// MarkForDeletion mirrors Enterprise::Account#mark_for_deletion by storing the
// scheduled deletion timestamp and reason in account custom_attributes.
func (s *AccountService) MarkForDeletion(ctx context.Context, accountID, userID uint, reason string) (*model.Account, error) {
	account, err := s.repo.FindByUserAndID(ctx, userID, accountID)
	if err != nil {
		return nil, err
	}
	attrs := account.CustomAttributesMap()
	if reason != "manual_deletion" {
		reason = "inactivity"
	}
	attrs["marked_for_deletion_at"] = time.Now().AddDate(0, 0, 7).Format(time.RFC3339)
	attrs["marked_for_deletion_reason"] = reason
	if err := account.SetCustomAttributesMap(attrs); err != nil {
		return nil, err
	}
	if err := s.repo.Update(ctx, account); err != nil {
		return nil, err
	}
	return account, nil
}

// UnmarkForDeletion removes Chatwoot's scheduled deletion custom attributes.
func (s *AccountService) UnmarkForDeletion(ctx context.Context, accountID, userID uint) (*model.Account, error) {
	account, err := s.repo.FindByUserAndID(ctx, userID, accountID)
	if err != nil {
		return nil, err
	}
	attrs := account.CustomAttributesMap()
	delete(attrs, "marked_for_deletion_at")
	delete(attrs, "marked_for_deletion_reason")
	if err := account.SetCustomAttributesMap(attrs); err != nil {
		return nil, err
	}
	if err := s.repo.Update(ctx, account); err != nil {
		return nil, err
	}
	return account, nil
}

// EnsureEnterpriseAccountCustomerCreationFlag tracks the Cloud subscription side
// effect that prevents duplicate Stripe customer creation jobs in Chatwoot.
func (s *AccountService) EnsureEnterpriseAccountCustomerCreationFlag(ctx context.Context, accountID, userID uint) error {
	account, err := s.repo.FindByUserAndID(ctx, userID, accountID)
	if err != nil {
		return err
	}
	attrs := account.CustomAttributesMap()
	if attrs["stripe_customer_id"] != nil || attrs["is_creating_customer"] != nil {
		return nil
	}
	attrs["is_creating_customer"] = true
	if err := account.SetCustomAttributesMap(attrs); err != nil {
		return err
	}
	return s.repo.Update(ctx, account)
}

func accountUsageLimit(limit int) int {
	if limit > 0 {
		return limit
	}
	return chatwootMaxLimit
}

func accountJSONMap(raw []byte) map[string]any {
	out := map[string]any{}
	if len(raw) > 0 {
		_ = json.Unmarshal(raw, &out)
	}
	return out
}

func accountDefaultCloudPlan(account *model.Account) bool {
	attrs := account.CustomAttributesMap()
	if value, ok := attrs["default_plan"]; ok {
		if enabled, ok := value.(bool); ok {
			return enabled
		}
	}
	return false
}

func captainUsageLimits(account *model.Account, documentsConsumed int64) map[string]any {
	limits := accountJSONMap(account.Limits)
	attrs := account.CustomAttributesMap()
	documentsAllowed := intFromAccountMap(limits, "captain_documents", chatwootMaxLimit)
	responsesAllowed := intFromAccountMap(limits, "captain_responses", chatwootMaxLimit)
	responsesConsumed := intFromAccountMap(attrs, "captain_responses_usage", 0)
	if docsAttr, ok := optionalIntFromAccountMap(attrs, "captain_documents_usage"); ok {
		documentsConsumed = int64(docsAttr)
	}

	return map[string]any{
		"documents": captainLimitBlock(documentsAllowed, int(documentsConsumed)),
		"responses": captainLimitBlock(responsesAllowed, responsesConsumed),
	}
}

func captainLimitBlock(total, consumed int) map[string]any {
	if consumed < 0 {
		consumed = 0
	}
	available := total - consumed
	if available < 0 {
		available = 0
	}
	if available > total {
		available = total
	}
	return map[string]any{"total_count": total, "current_available": available, "consumed": consumed}
}

func intFromAccountMap(values map[string]any, key string, fallback int) int {
	if value, ok := optionalIntFromAccountMap(values, key); ok {
		return value
	}
	return fallback
}

func optionalIntFromAccountMap(values map[string]any, key string) (int, bool) {
	value, ok := values[key]
	if !ok || value == nil {
		return 0, false
	}
	switch v := value.(type) {
	case int:
		return v, true
	case int64:
		return int(v), true
	case float64:
		return int(v), true
	case json.Number:
		n, err := v.Int64()
		return int(n), err == nil
	case string:
		var n int
		if _, err := fmt.Sscanf(v, "%d", &n); err == nil {
			return n, true
		}
	}
	return 0, false
}