//go:build linux || freebsd

package contactform

import (
	"net/mail"
	"strings"
	"unicode/utf8"
)

// validServices is the allow-list for contact-type forms.
var validServices = map[string]bool{
	"":               true,
	"architecture":   true,
	"ai":             true,
	"infrastructure": true,
	"software":       true,
	"unix":           true,
	"other":          true,
}

// MinNameRunes is the minimum allowed length of a name.
const MinNameRunes = 2

// MaxNameRunes is the maximum allowed length of a name.
const MaxNameRunes = 100

// MinMessageRunes is the minimum allowed length of a message body.
const MinMessageRunes = 10

// MaxMessageRunes is the maximum allowed length of a message body.
const MaxMessageRunes = 5000

// Validate dispatches to the correct type-specific validator.
// Supported types: contact, feedback, newsletter, generic. Default is "contact".
func Validate(r *Request, formType string) []FieldError {
	switch formType {
	case "newsletter":
		return validateNewsletter(r)
	case "feedback", "generic":
		return validateGeneric(r)
	default:
		return validateContact(r)
	}
}

func validateContact(r *Request) []FieldError {
	r.Name = strings.TrimSpace(r.Name)
	r.Email = strings.TrimSpace(r.Email)
	r.Service = strings.TrimSpace(r.Service)
	r.Message = strings.TrimSpace(r.Message)

	var errs []FieldError

	if n := utf8.RuneCountInString(r.Name); n < MinNameRunes {
		errs = append(errs, FieldError{Field: "name", Message: "name must be at least 2 characters"})
	} else if n > MaxNameRunes {
		errs = append(errs, FieldError{Field: "name", Message: "name must be at most 100 characters"})
	}

	if _, err := mail.ParseAddress(r.Email); err != nil {
		errs = append(errs, FieldError{Field: "email", Message: "email is invalid"})
	}

	if !validServices[r.Service] {
		errs = append(errs, FieldError{Field: "service", Message: "service is not a recognised value"})
	}

	if n := utf8.RuneCountInString(r.Message); n < MinMessageRunes {
		errs = append(errs, FieldError{Field: "message", Message: "message must be at least 10 characters"})
	} else if n > MaxMessageRunes {
		errs = append(errs, FieldError{Field: "message", Message: "message must be at most 5000 characters"})
	}

	return errs
}

func validateNewsletter(r *Request) []FieldError {
	r.Email = strings.TrimSpace(r.Email)

	if _, err := mail.ParseAddress(r.Email); err != nil {
		return []FieldError{{Field: "email", Message: "email is invalid"}}
	}
	return nil
}

func validateGeneric(r *Request) []FieldError {
	r.Name = strings.TrimSpace(r.Name)
	r.Email = strings.TrimSpace(r.Email)
	r.Message = strings.TrimSpace(r.Message)

	var errs []FieldError

	if n := utf8.RuneCountInString(r.Name); n < MinNameRunes {
		errs = append(errs, FieldError{Field: "name", Message: "name must be at least 2 characters"})
	} else if n > MaxNameRunes {
		errs = append(errs, FieldError{Field: "name", Message: "name must be at most 100 characters"})
	}

	if _, err := mail.ParseAddress(r.Email); err != nil {
		errs = append(errs, FieldError{Field: "email", Message: "email is invalid"})
	}

	if n := utf8.RuneCountInString(r.Message); n < MinMessageRunes {
		errs = append(errs, FieldError{Field: "message", Message: "message must be at least 10 characters"})
	} else if n > MaxMessageRunes {
		errs = append(errs, FieldError{Field: "message", Message: "message must be at most 5000 characters"})
	}

	return errs
}