// Package template defines the logical template entity used by the
// filesystem-backed Mail Service template catalog.
package template

import (
	"fmt"
	"strings"

	"galaxy/mail/internal/domain/common"
)

// Template stores one locale-specific template bundle.
type Template struct {
	// TemplateID identifies the template family.
	TemplateID common.TemplateID

	// Locale stores the canonical locale of the template variant.
	Locale common.Locale

	// SubjectTemplate stores the subject template source.
	SubjectTemplate string

	// TextTemplate stores the plaintext body template source.
	TextTemplate string

	// HTMLTemplate stores the optional HTML body template source.
	HTMLTemplate string

	// Version stores the template version marker projected into the domain
	// model.
	Version string
}

// Validate reports whether Template satisfies the frozen Stage 2 structural
// invariants.
func (record Template) Validate() error {
	if err := record.TemplateID.Validate(); err != nil {
		return fmt.Errorf("template id: %w", err)
	}
	if err := record.Locale.Validate(); err != nil {
		return fmt.Errorf("template locale: %w", err)
	}
	if record.SubjectTemplate == "" {
		return fmt.Errorf("template subject template must not be empty")
	}
	if record.TextTemplate == "" {
		return fmt.Errorf("template text template must not be empty")
	}
	if err := validateToken("template version", record.Version); err != nil {
		return err
	}

	return nil
}

func validateToken(name string, value string) error {
	switch {
	case strings.TrimSpace(value) == "":
		return fmt.Errorf("%s must not be empty", name)
	case strings.TrimSpace(value) != value:
		return fmt.Errorf("%s must not contain surrounding whitespace", name)
	default:
		return nil
	}
}