package mail

import (
	"context"
	"log"
	"strings"
	"time"

	"plumber/internal/events"
	"plumber/internal/store"
)

// Subscribe sends reply emails from PostCreated events. Nop or nil is a no-op.
func Subscribe(bus *events.Bus, st store.Store, n Notifier) {
	if bus == nil || st == nil || n == nil {
		return
	}
	if _, disabled := n.(Nop); disabled {
		return
	}
	s := subscriber{store: st, mail: n}
	bus.Subscribe(s.handle)
}

type subscriber struct {
	store store.Store
	mail  Notifier
}

func (s subscriber) handle(_ context.Context, ev any) {
	created, ok := ev.(events.PostCreated)
	if !ok {
		return
	}
	if strings.TrimSpace(created.ParentID) == "" {
		return
	}
	go s.notifyReply(created.PostEvent)
}

func (s subscriber) notifyReply(ev events.PostEvent) {
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	parent, err := s.store.GetPost(ctx, ev.ParentID)
	if err != nil {
		log.Printf("notify reply %s: load parent: %v", ev.PostID, err)
		return
	}
	root, err := s.store.GetPost(ctx, ev.RootID)
	if err != nil {
		log.Printf("notify reply %s: load root: %v", ev.PostID, err)
		return
	}
	author, err := s.store.UserByID(ctx, ev.AuthorID)
	if err != nil {
		log.Printf("notify reply %s: load author: %v", ev.PostID, err)
		return
	}
	recipientID := parent.AuthorID
	if author.Admin() {
		recipientID = root.AuthorID
	}
	if recipientID == author.ID {
		return
	}
	msg := PostReply{
		RootID:          root.ID,
		RootTitle:       root.Title,
		ReplyID:         ev.PostID,
		ReplyBody:       ev.Body,
		ReplyAuthorName: author.Name,
	}
	recipient, err := s.store.UserByID(ctx, recipientID)
	if err != nil {
		log.Printf("notify reply %s: load recipient: %v", msg.ReplyID, err)
		return
	}
	if recipient == nil || strings.TrimSpace(recipient.Email) == "" {
		return
	}
	msg.ToEmail = recipient.Email
	msg.ToName = recipient.Name
	if err := s.mail.NotifyPostReply(ctx, msg); err != nil {
		log.Printf("notify reply %s: %v", msg.ReplyID, err)
		return
	}
	log.Printf("notify reply %s: accepted", msg.ReplyID)
}