package service

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

	"github.com/gochat/gochat/internal/channel"
	"github.com/gochat/gochat/internal/model"
	"github.com/gochat/gochat/internal/worker"
	"gorm.io/gorm"
)

const TaskTypeMessageSendReply = "message:send_reply"

type sendReplyJob struct {
	MessageID uint `json:"message_id"`
}

var messageDeliveryRegistrations sync.Map

// RegisterMessageDeliveryJobs wires Chatwoot's SendReplyJob equivalent into
// the durable worker. Outgoing provider calls stay behind channel providers so
// tests can fake delivery without real external APIs.
func RegisterMessageDeliveryJobs(wp *worker.WorkerPool, db *gorm.DB, dispatcher *channel.Dispatcher) {
	if wp == nil || db == nil {
		return
	}
	if _, loaded := messageDeliveryRegistrations.LoadOrStore(wp, struct{}{}); loaded {
		return
	}
	runner := &messageDeliveryRunner{db: db, dispatcher: dispatcher}
	wp.Register(TaskTypeMessageSendReply, runner.performSendReply)
}

func EnqueueSendReply(ctx context.Context, wp *worker.WorkerPool, messageID uint) (*model.BackgroundJob, error) {
	if wp == nil {
		return nil, nil
	}
	if messageID == 0 {
		return nil, fmt.Errorf("invalid send reply payload: message_id=%d", messageID)
	}
	return wp.Enqueue(ctx, TaskTypeMessageSendReply, sendReplyJob{MessageID: messageID},
		worker.WithQueue("high"),
		worker.WithMaxAttempts(3),
		worker.WithIdempotencyKey(fmt.Sprintf("message:send_reply:%d", messageID)),
	)
}

type messageDeliveryRunner struct {
	db         *gorm.DB
	dispatcher *channel.Dispatcher
}

func (r *messageDeliveryRunner) performSendReply(ctx context.Context, job *model.BackgroundJob) error {
	var payload sendReplyJob
	if err := json.Unmarshal(job.Payload, &payload); err != nil {
		return fmt.Errorf("unmarshal send reply job: %w", err)
	}
	if payload.MessageID == 0 {
		return fmt.Errorf("invalid send reply job payload: %#v", payload)
	}

	var message model.Message
	if err := r.db.WithContext(ctx).First(&message, payload.MessageID).Error; err != nil {
		return fmt.Errorf("load send reply message %d: %w", payload.MessageID, err)
	}
	if !deliverableReplyMessage(message) {
		return nil
	}

	var conversation model.Conversation
	if err := r.db.WithContext(ctx).
		Where("id = ? AND account_id = ?", message.ConversationID, message.AccountID).
		First(&conversation).Error; err != nil {
		return fmt.Errorf("load send reply conversation %d: %w", message.ConversationID, err)
	}

	var inbox model.Inbox
	if err := r.db.WithContext(ctx).
		Where("id = ? AND account_id = ?", message.InboxID, message.AccountID).
		First(&inbox).Error; err != nil {
		return fmt.Errorf("load send reply inbox %d: %w", message.InboxID, err)
	}

	var contact model.Contact
	if err := r.db.WithContext(ctx).
		Where("id = ? AND account_id = ?", conversation.ContactID, message.AccountID).
		First(&contact).Error; err != nil {
		return fmt.Errorf("load send reply contact %d: %w", conversation.ContactID, err)
	}

	result, err := channel.SendMessageToChannel(ctx, channel.ChannelType(inbox.ChannelType), &inbox, &message, &contact)
	if err != nil {
		_ = r.updateMessageDeliveryFailure(ctx, &message, err)
		return fmt.Errorf("send reply message %d: %w", message.ID, err)
	}
	if err := r.updateMessageDeliverySuccess(ctx, &message, result); err != nil {
		return err
	}
	return nil
}

func deliverableReplyMessage(message model.Message) bool {
	if message.SourceID != "" || message.Private || message.ContentType == "voice_call" {
		return false
	}
	switch message.MessageType {
	case string(model.MessageTypeOutgoing), string(model.MessageTypeTemplate):
		return true
	default:
		return false
	}
}

func (r *messageDeliveryRunner) updateMessageDeliverySuccess(ctx context.Context, message *model.Message, result *channel.SendResult) error {
	updates := map[string]any{
		"status":             string(model.MessageStatusSent),
		"content_attributes": setMessageExternalError(message.ContentAttributes, string(model.MessageStatusSent), ""),
	}
	if result != nil && result.ExternalID != "" {
		updates["source_id"] = result.ExternalID
	}
	if err := r.db.WithContext(ctx).Model(&model.Message{}).Where("id = ?", message.ID).Updates(updates).Error; err != nil {
		return fmt.Errorf("update sent message %d: %w", message.ID, err)
	}
	r.dispatchMessageStatus(ctx, message, string(model.MessageStatusSent))
	return nil
}

func (r *messageDeliveryRunner) updateMessageDeliveryFailure(ctx context.Context, message *model.Message, sendErr error) error {
	updates := map[string]any{
		"status":             string(model.MessageStatusFailed),
		"content_attributes": setMessageExternalError(message.ContentAttributes, string(model.MessageStatusFailed), sendErr.Error()),
	}
	return r.db.WithContext(ctx).Model(message).
		Where("id = ?", message.ID).
		Updates(updates).Error
}

func (r *messageDeliveryRunner) dispatchMessageStatus(ctx context.Context, message *model.Message, status string) {
	if r.dispatcher == nil {
		return
	}
	event := channel.NewChannelEvent(channel.EventMessageStatusUpdated, channel.ChannelAPI, message.AccountID, message.InboxID)
	event.ConversationID = message.ConversationID
	if message.SenderID != nil {
		event.UserID = *message.SenderID
	}
	event.Data["message_id"] = message.ID
	event.Data["status"] = status
	_ = r.dispatcher.Dispatch(ctx, event)
}