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|
package htmlconv
import (
"bytes"
"html/template"
"io"
"strings"
"tildegit.org/tjp/sliderule/gopher"
"tildegit.org/tjp/sliderule/internal/types"
)
// Convert writes html to a writer from the provided gophermap document.
//
// Templates can be provided to override the output for different line types.
// The supported templates are:
// - "header' is called before any lines and is passed the full document.
// - "footer" is called after all lines and is passed the full document.
// - "message" is called for every group of consecutive info-message lines. It is
// passed a string of all the display components of the included lines, joined by
// newline characters.
// - "image" is called for all lines of any of the following types: GifFileType,
// ImageFileType, BitmapType, PngImageFileType. It is passed the gopher.MapItem.
// - "link" is called for all lines of any other type not yet mentioned, and is passed
// the gopher.MapItem.
//
// There are already default implementations of each of these templates, so the "overrides"
// argument can be nil or include just a subset of the supported templates.
func Convert(wr io.Writer, doc gopher.MapDocument, overrides *template.Template) error {
tmpl, err := baseTmpl.Clone()
if err != nil {
return err
}
tmpl, err = addOverrides(tmpl, overrides)
if err != nil {
return err
}
for _, item := range renderItems(doc) {
if err := tmpl.ExecuteTemplate(wr, item.template, item.object); err != nil {
return err
}
}
return nil
}
type renderItem struct {
template string
object any
}
type renderRef struct {
Type types.Status
Display string
Selector template.URL
Hostname string
Port string
}
func refItem(item gopher.MapItem) renderRef {
return renderRef{
Type: item.Type,
Display: item.Display,
Selector: template.URL(item.Selector),
Hostname: item.Hostname,
Port: item.Port,
}
}
func renderItems(doc gopher.MapDocument) []renderItem {
out := make([]renderItem, 0, len(doc))
out = append(out, renderItem{
template: "header",
object: doc,
})
inMsg := false
msg := &bytes.Buffer{}
var currentHost, currentPort string
for _, mapItem := range doc {
switch mapItem.Type {
case gopher.InfoMessageType:
if inMsg {
_, _ = msg.WriteString("\n")
} else {
msg.Reset()
}
_, _ = msg.WriteString(mapItem.Display)
inMsg = true
if currentHost == "" {
currentHost = mapItem.Hostname
}
if currentPort == "" {
currentPort = mapItem.Port
}
case gopher.GifFileType, gopher.ImageFileType, gopher.BitmapType, gopher.PngImageFileType:
if inMsg {
out = append(out, renderItem{
template: "message",
object: msg.String(),
})
inMsg = false
}
out = append(out, renderItem{
template: "image",
object: refItem(mapItem),
})
default:
if inMsg {
out = append(out, renderItem{
template: "message",
object: msg.String(),
})
inMsg = false
}
out = append(out, renderItem{
template: "link",
object: refItem(mapItem),
})
}
}
if inMsg {
out = append(out, renderItem{
template: "message",
object: msg.String(),
})
}
simplifyLinks(out, currentHost, currentPort)
return append(out, renderItem{
template: "footer",
object: doc,
})
}
func simplifyLinks(items []renderItem, currentHost, currentPort string) {
for i, item := range items {
if item.template != "link" && item.template != "image" {
continue
}
m := item.object.(renderRef)
if m.Hostname == currentHost && m.Port == currentPort {
m.Hostname = ""
m.Port = ""
m.Selector = template.URL(strings.TrimPrefix(string(m.Selector), "URL:"))
items[i].object = m
}
}
}
func addOverrides(base *template.Template, overrides *template.Template) (*template.Template, error) {
if overrides == nil {
return base, nil
}
tmpl := base
var err error
for _, override := range overrides.Templates() {
tmpl, err = tmpl.AddParseTree(override.Name(), override.Tree)
if err != nil {
return nil, err
}
}
return tmpl, nil
}
var baseTmpl = template.Must(template.New("htmlconv").Parse(`
{{ define "header" -}}
<!DOCTYPE html>
<html><body class="gophermap">
{{- end }}
{{ define "message" -}}
<pre class="gophermap">{{.}}
</pre>
{{- end }}
{{ define "link" -}}
<p class="gophermap"><a class="gophermap" {{ if .Hostname | and .Port }}href="gopher://{{.Hostname}}:{{.Port}}{{.Selector}}"{{ else }}href="{{.Selector}}"{{ end }}>{{.Display}}</a></p>
{{- end }}
{{ define "image" -}}
<p class="gophermap"><img class="gophermap" {{ if .Hostname | and .Port }}src="gopher://{{.Hostname}}:{{.Port}}{{.Selector}}"{{ else }}src="{{.Selector}}"{{ end }} alt="{{.Display}}"/></p>
{{- end }}
{{ define "footer" -}}
</body></html>
{{ end }}
`))
|
