2020-06-20 00:09:01 -04:00
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package renderer
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import (
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"errors"
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"io/ioutil"
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"mime"
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"strings"
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"github.com/makeworld-the-better-one/amfora/structs"
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"github.com/makeworld-the-better-one/go-gemini"
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"golang.org/x/text/encoding/ianaindex"
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)
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// isUTF8 returns true for charsets that are compatible with UTF-8 and don't need to be decoded.
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func isUTF8(charset string) bool {
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utfCharsets := []string{"", "utf-8", "us-ascii"}
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for i := range utfCharsets {
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if strings.ToLower(charset) == utfCharsets[i] {
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return true
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}
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}
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return false
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}
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// CanDisplay returns true if the response is supported by Amfora
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// for displaying on the screen.
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// It also doubles as a function to detect whether something can be stored in a Page struct.
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func CanDisplay(res *gemini.Response) bool {
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if gemini.SimplifyStatus(res.Status) != 20 {
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// No content
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return false
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}
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mediatype, params, err := mime.ParseMediaType(res.Meta)
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if err != nil {
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return false
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}
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2020-06-21 23:49:43 -04:00
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if !strings.HasPrefix(mediatype, "text/") {
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2020-06-20 00:09:01 -04:00
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// Amfora doesn't support other filetypes
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return false
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}
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if isUTF8(params["charset"]) {
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return true
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}
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enc, err := ianaindex.MIME.Encoding(params["charset"]) // Lowercasing is done inside
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// Encoding sometimes returns nil, see #3 on this repo and golang/go#19421
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return err == nil && enc != nil
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}
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2020-06-21 16:53:12 -04:00
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func MakePage(url string, res *gemini.Response, width int) (*structs.Page, error) {
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2020-06-20 00:09:01 -04:00
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if !CanDisplay(res) {
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return nil, errors.New("not valid content for a Page")
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}
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rawText, err := ioutil.ReadAll(res.Body) // TODO: Don't use all memory on large pages
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if err != nil {
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return nil, err
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}
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res.Body.Close()
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mediatype, params, _ := mime.ParseMediaType(res.Meta)
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// Convert content first
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var utfText string
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if isUTF8(params["charset"]) {
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utfText = string(rawText)
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} else {
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encoding, err := ianaindex.MIME.Encoding(params["charset"])
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if encoding == nil || err != nil {
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// Some encoding doesn't exist and wasn't caught in CanDisplay()
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return nil, errors.New("unsupported encoding")
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}
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utfText, err = encoding.NewDecoder().String(string(rawText))
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if err != nil {
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return nil, err
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}
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}
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if mediatype == "text/gemini" {
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2020-06-21 16:53:12 -04:00
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rendered, links := RenderGemini(utfText, width)
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2020-06-20 00:09:01 -04:00
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return &structs.Page{
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Url: url,
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Content: rendered,
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Links: links,
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}, nil
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2020-06-21 23:49:43 -04:00
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} else if strings.HasPrefix(mediatype, "text/") {
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return &structs.Page{
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Url: url,
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Content: utfText,
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Links: []string{}, // Non-gemini links are not supported
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}, nil
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2020-06-20 00:09:01 -04:00
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}
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return nil, errors.New("displayable mediatype is not handled in the code, implementation error")
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}
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