package renderer import ( "errors" "io/ioutil" "mime" "strings" "github.com/makeworld-the-better-one/amfora/structs" "github.com/makeworld-the-better-one/go-gemini" "golang.org/x/text/encoding/ianaindex" ) // isUTF8 returns true for charsets that are compatible with UTF-8 and don't need to be decoded. func isUTF8(charset string) bool { utfCharsets := []string{"", "utf-8", "us-ascii"} for i := range utfCharsets { if strings.ToLower(charset) == utfCharsets[i] { return true } } return false } // CanDisplay returns true if the response is supported by Amfora // for displaying on the screen. // It also doubles as a function to detect whether something can be stored in a Page struct. func CanDisplay(res *gemini.Response) bool { if gemini.SimplifyStatus(res.Status) != 20 { // No content return false } mediatype, params, err := mime.ParseMediaType(res.Meta) if err != nil { return false } if mediatype != "text/gemini" && mediatype != "text/plain" { // Amfora doesn't support other filetypes return false } if isUTF8(params["charset"]) { return true } enc, err := ianaindex.MIME.Encoding(params["charset"]) // Lowercasing is done inside // Encoding sometimes returns nil, see #3 on this repo and golang/go#19421 return err == nil && enc != nil } func MakePage(url string, res *gemini.Response) (*structs.Page, error) { if !CanDisplay(res) { return nil, errors.New("not valid content for a Page") } rawText, err := ioutil.ReadAll(res.Body) // TODO: Don't use all memory on large pages if err != nil { return nil, err } res.Body.Close() mediatype, params, _ := mime.ParseMediaType(res.Meta) // Convert content first var utfText string if isUTF8(params["charset"]) { utfText = string(rawText) } else { encoding, err := ianaindex.MIME.Encoding(params["charset"]) if encoding == nil || err != nil { // Some encoding doesn't exist and wasn't caught in CanDisplay() return nil, errors.New("unsupported encoding") } utfText, err = encoding.NewDecoder().String(string(rawText)) if err != nil { return nil, err } } if mediatype == "text/plain" { return &structs.Page{ Url: url, Content: utfText, Links: []string{}, // Plaintext has no links }, nil } if mediatype == "text/gemini" { rendered, links := RenderGemini(utfText) return &structs.Page{ Url: url, Content: rendered, Links: links, }, nil } return nil, errors.New("displayable mediatype is not handled in the code, implementation error") }