package webhook

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

	"github.com/google/uuid"
	"gorm.io/datatypes"
	"gorm.io/gorm"

	"github.com/gochat/gochat/internal/channel"
	"github.com/gochat/gochat/internal/model"
)

// IncomingPersister is the durable boundary after provider-specific webhook parsing.
// Reference: Chatwoot IncomingMessageService creates ContactInbox, Conversation, and Message.
type IncomingPersister struct {
	db *gorm.DB
}

type IncomingPersistResult struct {
	Contact      *model.Contact
	ContactInbox *model.ContactInbox
	Conversation *model.Conversation
	Message      *model.Message
	Duplicate    bool
}

func NewIncomingPersister(db *gorm.DB) *IncomingPersister {
	if db == nil {
		return nil
	}
	return &IncomingPersister{db: db}
}

func (p *IncomingPersister) PersistIncoming(ctx context.Context, inbox *model.Inbox, msg *channel.IncomingMessage) (*IncomingPersistResult, error) {
	if p == nil || p.db == nil || inbox == nil || msg == nil {
		return nil, nil
	}
	if msg.SourceID == "" {
		return nil, fmt.Errorf("incoming message missing source_id")
	}
	senderID := msg.SenderID
	if senderID == "" {
		senderID = msg.ConversationID
	}
	if senderID == "" {
		return nil, fmt.Errorf("incoming message missing sender_id")
	}
	if msg.Content == "" && len(msg.Attachments) == 0 {
		return nil, fmt.Errorf("incoming message has no content or attachments")
	}

	var result IncomingPersistResult
	err := p.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		var existingMessage model.Message
		if err := tx.Where("inbox_id = ? AND source_id = ?", inbox.ID, msg.SourceID).First(&existingMessage).Error; err == nil {
			result.Message = &existingMessage
			result.Duplicate = true
			return nil
		} else if err != gorm.ErrRecordNotFound {
			return err
		}

		contact, contactInbox, err := p.resolveOrCreateContactInbox(ctx, tx, inbox, msg, senderID)
		if err != nil {
			return err
		}
		result.Contact = contact
		result.ContactInbox = contactInbox

		conversation, err := p.resolveOrCreateConversation(ctx, tx, inbox, contact, contactInbox, msg)
		if err != nil {
			return err
		}
		result.Conversation = conversation

		message, err := p.createMessage(ctx, tx, inbox, conversation, contact, msg)
		if err != nil {
			return err
		}
		result.Message = message
		return nil
	})
	if err != nil {
		return nil, err
	}
	return &result, nil
}

func (p *IncomingPersister) resolveOrCreateContactInbox(ctx context.Context, tx *gorm.DB, inbox *model.Inbox, msg *channel.IncomingMessage, senderID string) (*model.Contact, *model.ContactInbox, error) {
	var contactInbox model.ContactInbox
	if err := tx.WithContext(ctx).Preload("Contact").Where("inbox_id = ? AND source_id = ?", inbox.ID, senderID).First(&contactInbox).Error; err == nil {
		contact := contactInbox.Contact
		updates := map[string]interface{}{}
		if msg.SenderName != "" && contact.Name != msg.SenderName {
			updates["name"] = msg.SenderName
		}
		if len(updates) > 0 {
			if err := tx.WithContext(ctx).Model(&contact).Updates(updates).Error; err != nil {
				return nil, nil, err
			}
			if err := tx.WithContext(ctx).First(&contact, contact.ID).Error; err != nil {
				return nil, nil, err
			}
		}
		return &contact, &contactInbox, nil
	} else if err != gorm.ErrRecordNotFound {
		return nil, nil, err
	}

	name := msg.SenderName
	if name == "" {
		name = senderID
	}
	attrs := mergeChannelConfig(msg.SenderExtra, map[string]interface{}{
		"source_id":    senderID,
		"channel_type": string(msg.ChannelType),
	})
	contact := model.Contact{
		AccountID:            inbox.AccountID,
		Name:                 name,
		Identifier:           senderID,
		SourceID:             string(msg.ChannelType),
		AdditionalAttributes: mustJSON(attrs),
		CustomAttributes:     datatypes.JSON("{}"),
	}
	if err := tx.WithContext(ctx).Create(&contact).Error; err != nil {
		return nil, nil, err
	}

	contactInbox = model.ContactInbox{
		ContactID:   contact.ID,
		InboxID:     inbox.ID,
		SourceID:    senderID,
		PubsubToken: uuid.NewString(),
	}
	if err := tx.WithContext(ctx).Create(&contactInbox).Error; err != nil {
		return nil, nil, err
	}
	return &contact, &contactInbox, nil
}

func (p *IncomingPersister) resolveOrCreateConversation(ctx context.Context, tx *gorm.DB, inbox *model.Inbox, contact *model.Contact, contactInbox *model.ContactInbox, msg *channel.IncomingMessage) (*model.Conversation, error) {
	var conversation model.Conversation
	if err := tx.WithContext(ctx).
		Where("account_id = ? AND inbox_id = ? AND contact_id = ? AND status = ?", inbox.AccountID, inbox.ID, contact.ID, model.ConversationStatusOpen).
		Order("id DESC").First(&conversation).Error; err == nil {
		now := time.Now().Unix()
		_ = tx.WithContext(ctx).Model(&conversation).Updates(map[string]interface{}{
			"last_activity_at": now,
			"last_message_at":  now,
		}).Error
		return &conversation, nil
	} else if err != gorm.ErrRecordNotFound {
		return nil, err
	}

	now := time.Now().Unix()
	channelType := inbox.ChannelType
	if msg.ChannelType != "" {
		channelType = string(msg.ChannelType)
	}
	conversation = model.Conversation{
		AccountID:            inbox.AccountID,
		InboxID:              inbox.ID,
		ContactID:            contact.ID,
		ContactInboxID:       &contactInbox.ID,
		Status:               string(model.ConversationStatusOpen),
		Priority:             "none",
		ChannelType:          channelType,
		Channel:              inbox.ChannelType,
		LastActivityAt:       &now,
		LastMessageAt:        &now,
		LastNonSysMsgAt:      &now,
		AdditionalAttributes: mustJSON(mergeChannelConfig(msg.ConversationExtra, map[string]interface{}{"external_conversation_id": msg.ConversationID})),
		CustomAttributes:     datatypes.JSON("{}"),
	}
	if err := tx.WithContext(ctx).Create(&conversation).Error; err != nil {
		return nil, err
	}
	return &conversation, nil
}

func (p *IncomingPersister) createMessage(ctx context.Context, tx *gorm.DB, inbox *model.Inbox, conversation *model.Conversation, contact *model.Contact, msg *channel.IncomingMessage) (*model.Message, error) {
	contentAttrs := map[string]interface{}{}
	if len(msg.Attachments) > 0 {
		contentAttrs["attachments"] = msg.Attachments
	}
	if msg.ReplyToID != "" {
		contentAttrs["in_reply_to"] = msg.ReplyToID
	}
	message := model.Message{
		ConversationID:       conversation.ID,
		AccountID:            inbox.AccountID,
		InboxID:              inbox.ID,
		SenderID:             &contact.ID,
		SenderType:           string(model.SenderTypeContact),
		Content:              msg.Content,
		ContentType:          mapIncomingContentType(msg.ContentType),
		Status:               string(model.MessageStatusSent),
		MessageType:          string(model.MessageTypeIncoming),
		SourceID:             msg.SourceID,
		ContentAttributes:    mustJSON(contentAttrs),
		AdditionalAttributes: mustJSON(msg.Extra),
	}
	if err := tx.WithContext(ctx).Create(&message).Error; err != nil {
		return nil, err
	}
	return &message, nil
}

func mapIncomingContentType(contentType channel.ContentType) string {
	switch contentType {
	case channel.ContentImage:
		return string(model.MessageContentTypeImage)
	case channel.ContentAudio:
		return string(model.MessageContentTypeAudio)
	case channel.ContentVideo:
		return string(model.MessageContentTypeVideo)
	case channel.ContentFile:
		return string(model.MessageContentTypeFile)
	case channel.ContentLocation:
		return string(model.MessageContentTypeLocation)
	default:
		return string(model.MessageContentTypeText)
	}
}

func mergeChannelConfig(base channel.ChannelConfig, extra map[string]interface{}) map[string]interface{} {
	merged := map[string]interface{}{}
	for k, v := range base {
		merged[k] = v
	}
	for k, v := range extra {
		if v != "" && v != nil {
			merged[k] = v
		}
	}
	return merged
}

func mustJSON(value interface{}) datatypes.JSON {
	if value == nil {
		return datatypes.JSON("{}")
	}
	data, err := json.Marshal(value)
	if err != nil || len(data) == 0 {
		return datatypes.JSON("{}")
	}
	return datatypes.JSON(data)
}