package main

import (
	"fmt"
	"strings"
)

// UpsertChannel — create or update a channel. Channels are lightweight tags.
type UpsertChannel struct {
	Slug        string
	Name        string
	Description string
}

func (m *UpsertChannel) Kind() string { return "upsert_channel" }

func (m *UpsertChannel) AffectedAuthors() []string {
	return nil // channels don't attribute to an author
}

func (m *UpsertChannel) Validate(s *Store) error {
	if strings.TrimSpace(m.Slug) == "" {
		return &ValidationError{Field: "slug", Message: "required"}
	}
	for _, r := range m.Slug {
		if r == ' ' || r == '\t' || r == '\n' || r == '/' {
			return &ValidationError{Field: "slug", Message: "must not contain whitespace or slashes"}
		}
	}
	if strings.TrimSpace(m.Name) == "" {
		return &ValidationError{Field: "name", Message: "required"}
	}
	return nil
}

func (m *UpsertChannel) Apply(s *Store, lock LockRegion) error {
	now := s.Now()
	c := &Channel{
		Slug:        m.Slug,
		Name:        m.Name,
		Description: m.Description,
		CreatedAt:   now,
	}
	s.mu.Lock()
	defer s.mu.Unlock()
	if existing, ok := s.channels[m.Slug]; ok {
		c.CreatedAt = existing.CreatedAt
	}
	s.channels[m.Slug] = c
	return nil
}

var _ = fmt.Sprintf // keep fmt for future error formatting