package mailx

import (
    "net/textproto"
    "sort"
)

func Fields2Mimeheader(fields []Field) textproto.MIMEHeader {
    h := make(textproto.MIMEHeader)
    for _, field := range fields {
        h.Add(field.Name, field.Body)
    }
    return h
}

func Mimeheader2Fields(h textproto.MIMEHeader) []Field {
    seen := make(map[string]bool)
    var names []string
    for name := range h {
        name = textproto.CanonicalMIMEHeaderKey(name)
        if !seen[name] {
            names = append(names, name)
        }
        seen[name] = true
    }
    sort.Strings(names)

    var fields []Field
    for _, name := range names {
        for _, v := range h.Values(name) {
            fields = append(fields, Field{Name: name, Body: v,})
        }
    }
    return fields
}