package runtime

import (
	"context"
	"regexp"
	"slices"
	"strings"

	"code.tczkiot.com/wlw/ai-agent/identity"
	"code.tczkiot.com/wlw/ai-agent/internal/models"
	"code.tczkiot.com/wlw/ai-agent/internal/pkg/enums"
	"code.tczkiot.com/wlw/ai-agent/internal/pkg/utils"
	svc "code.tczkiot.com/wlw/ai-agent/internal/services"
)

const (
	missingBusinessIdentityReply = "暂未识别到您要咨询的业务对象。\n\n" +
		"卡板用户：请发送“卡号 + 您的卡号”\n" +
		"设备用户：请发送“设备号 + 您的设备号”\n" +
		"商城用户：请先登录商城，再从商城的客服入口进入。\n\n" +
		"识别成功后即可继续查询；需要人工协助可回复“人工客服”。"
	invalidBusinessIdentityReply = "没有查询到您发送的卡号或设备号，请核对后重新发送。\n\n" +
		"卡板用户：发送“卡号 + 您的卡号”\n" +
		"设备用户：发送“设备号 + 您的设备号”\n" +
		"商城用户：请登录商城后从客服入口进入。"
	identityLookupFailedReply = "业务身份识别暂时不可用，请稍后重试，或回复“人工客服”。"
)

var businessIdentifierPattern = regexp.MustCompile(`[A-Za-z0-9][A-Za-z0-9:_-]{5,63}`)

type guestBusinessIdentityResolution struct {
	Conversation      models.Conversation
	NeedsPrompt       bool
	CandidateProvided bool
}

func resolveGuestBusinessIdentity(ctx context.Context, conversation models.Conversation, message models.Message) (guestBusinessIdentityResolution, error) {
	resolution := guestBusinessIdentityResolution{Conversation: conversation}
	messageContent := businessIdentityMessageContent(message)
	if isBoundBusinessCustomerType(conversation.CustomerType) || isHumanHandoffMessage(messageContent) {
		return resolution, nil
	}

	currentCandidates, currentCandidateProvided := businessIdentityCandidates(messageContent)
	resolution.CandidateProvided = currentCandidateProvided
	if subject, ok, err := resolveBusinessSubject(ctx, messageContent, currentCandidates); err != nil {
		return resolution, err
	} else if ok {
		resolution.Conversation = conversationWithBusinessSubject(conversation, subject)
		return resolution, nil
	}

	history, _, _ := svc.MessageService.FindByConversationIDCursor(
		conversation.ID,
		0,
		20,
		string(enums.IMSenderTypeCustomer),
		"",
	)
	for index := len(history) - 1; index >= 0; index-- {
		item := history[index]
		if item.ID == message.ID {
			continue
		}
		if item.MessageType != enums.IMMessageTypeText && item.MessageType != enums.IMMessageTypeHTML {
			continue
		}
		content := businessIdentityMessageContent(item)
		candidates, _ := businessIdentityCandidates(content)
		if subject, ok, err := resolveBusinessSubject(ctx, content, candidates); err != nil {
			return resolution, err
		} else if ok {
			resolution.Conversation = conversationWithBusinessSubject(conversation, subject)
			return resolution, nil
		}
	}

	resolution.NeedsPrompt = true
	return resolution, nil
}

func businessIdentityMessageContent(message models.Message) string {
	return utils.BuildRuntimeMessageText(message.MessageType, message.Content)
}

func isBoundBusinessCustomerType(customerType string) bool {
	switch identity.SubjectType(strings.TrimSpace(customerType)) {
	case identity.SubjectCard, identity.SubjectDevice, identity.SubjectMallUser:
		return true
	default:
		return false
	}
}

func isHumanHandoffMessage(content string) bool {
	content = strings.ToLower(strings.TrimSpace(content))
	return strings.Contains(content, "人工") ||
		strings.Contains(content, "转接客服") ||
		strings.Contains(content, "human agent")
}

func businessIdentityCandidates(content string) ([]string, bool) {
	content = strings.TrimSpace(content)
	if content == "" {
		return nil, false
	}
	candidates := businessIdentifierPattern.FindAllString(content, -1)
	candidates = slices.Compact(candidates)
	lower := strings.ToLower(content)
	explicit := strings.Contains(content, "卡号") ||
		strings.Contains(content, "卡板") ||
		strings.Contains(content, "设备号") ||
		strings.Contains(lower, "iccid") ||
		strings.Contains(lower, "imei")
	if len(candidates) == 1 && candidates[0] == content {
		explicit = true
	}
	return candidates, explicit
}

func resolveBusinessSubject(ctx context.Context, content string, candidates []string) (identity.Subject, bool, error) {
	if len(candidates) == 0 {
		return identity.Subject{}, false, nil
	}
	types := []identity.SubjectType{identity.SubjectCard, identity.SubjectDevice}
	lower := strings.ToLower(content)
	switch {
	case strings.Contains(content, "设备") || strings.Contains(lower, "imei"):
		types = []identity.SubjectType{identity.SubjectDevice}
	case strings.Contains(content, "卡号") || strings.Contains(lower, "iccid"):
		types = []identity.SubjectType{identity.SubjectCard}
	}

	for _, candidate := range candidates {
		for _, subjectType := range types {
			subjects, err := svc.SubjectService.Query(ctx, identity.Query{
				Types:       []identity.SubjectType{subjectType},
				Keyword:     candidate,
				EnabledOnly: true,
			})
			if err != nil {
				return identity.Subject{}, false, err
			}
			for _, subject := range subjects {
				if businessSubjectMatchesIdentifier(subject, candidate) {
					return subject, true, nil
				}
			}
		}
	}
	return identity.Subject{}, false, nil
}

func businessSubjectMatchesIdentifier(subject identity.Subject, candidate string) bool {
	candidate = strings.TrimSpace(candidate)
	return strings.EqualFold(strings.TrimSpace(subject.Identifier), candidate) ||
		strings.EqualFold(strings.TrimSpace(subject.Username), candidate)
}

func conversationWithBusinessSubject(conversation models.Conversation, subject identity.Subject) models.Conversation {
	conversation.CustomerType = string(subject.Type)
	conversation.CustomerID = subject.ID
	externalID := strings.TrimSpace(subject.Identifier)
	if subject.Type == identity.SubjectCard && strings.TrimSpace(subject.Username) != "" {
		externalID = strings.TrimSpace(subject.Username)
	}
	conversation.CustomerExternalID = externalID
	conversation.CustomerName = strings.TrimSpace(subject.Name)
	return conversation
}

func guestBusinessIdentityPrompt(resolution guestBusinessIdentityResolution, err error) string {
	if err != nil {
		return identityLookupFailedReply
	}
	if resolution.CandidateProvided {
		return invalidBusinessIdentityReply
	}
	return missingBusinessIdentityReply
}