sw-convert and sw-fetch tools

1 files changed, 222 insertions, 0 deletions

diff --git a/tools/sw-convert/main.go b/tools/sw-convert/main.go
new file mode 100644
index 0000000..77a459c
--- /dev/null
+++ b/tools/sw-convert/main.go
@@ -0,0 +1,222 @@
+package main
+
+import (
+	htemplate "html/template"
+	"net/url"
+	"os"
+	"text/template"
+
+	"tildegit.org/tjp/sliderule/gemini/gemtext"
+	"tildegit.org/tjp/sliderule/gemini/gemtext/atomconv"
+	gem_htmlconv "tildegit.org/tjp/sliderule/gemini/gemtext/htmlconv"
+	gem_mdconv "tildegit.org/tjp/sliderule/gemini/gemtext/mdconv"
+	goph_htmlconv "tildegit.org/tjp/sliderule/gopher/gophermap/htmlconv"
+	"tildegit.org/tjp/sliderule/gopher/gophermap"
+	goph_mdconv "tildegit.org/tjp/sliderule/gopher/gophermap/mdconv"
+)
+
+const usage = `Conversions for small web formats.
+
+Usage:
+  sw-convert (-h | --help)
+  sw-convert --list-formats
+  sw-convert (-i INPUT | --input INPUT) (-o OUTPUT | --output OUTPUT) [-t PATH | --template PATH]
+
+Options:
+  -h --help           Show this screen.
+  --list-formats      List supported input and output formats.
+  -i --input INPUT    Format with which to parse standard input.
+  -o --output OUTPUT  Which format to write to standard output.
+  -t --template PATH  Path to a template file. May be specified more than once.
+  -l --location URL   URL the source came from. Required only for gemtext to atom conversion.
+
+Templates:
+  Template files provided by the -t/--template option should be in the golang template formats.
+  When converting to markdown they will be parsed by text/template (https://pkg.go.dev/text/template),
+  and for html conversions they will be parsed by html/template (https://pkg.go.dev/html/template).
+
+  The template names available for override depend on the type of the source document.
+
+  Gemtext:
+    "header" is rendered at the beginning of the document and is passed the full Document.
+    "footer" is rendered at the end of the document and is passed the full Document.
+    "textline" is rendered once for each plain text line, and is passed the Line.
+    "linkline" is rendered for each link line and is passed the Line.
+    "preformattedtextlines" is rendered for each block of pre-formatted text, and is passed a slice of Lines.
+    "heading1line", "heading2line", and "heading3line" are rendered for heading lines and are passed the Line.
+    "listitemlines" is rendered for any contiguous group of list item lines, and is passed a slice of the Lines.
+    "quoteline" is rendered for each block-quote line and is passed the Line.
+
+    The default gemtext->html templates define an HTML5 document with all HTML nodes given a class of "gemtext".
+
+    Document:
+      The header and footer templates are given the full document, which can be iterated over to produce all the lines.
+    Line:
+      Line-specific or line-group-specific templates are passed Line objects. These all have Type, Raw, and String methods, and some have type-specific additional methods.
+        - link lines also have URL() and Label() methods.
+        - heading, list item, and quote lines have a Body() method which omit the leading prefixes.
+
+  Gophermap:
+    "header" is rendered at the beginning of the document and is passed the full Document.
+    "footer" is rendered at the end of the document and is passed the full Document.
+    "message" is rendered for any contiguous group of info-message lines, and is passed a string of the newline-separated lines.
+    "image" is rendered for any gif file, bitmap file, png file, or image line types, and is passed the Map Item.
+    "link" is rendered for all other line types and is passed the Map Item.
+
+    The default gophermap->html templates define an HTML5 document with all HTML nodes given a class of "gophermap".
+
+    Document:
+      The full gophermap document object is a list of map items, additionally with a String() method which serializes the full document back into the gophermap format.
+    Map Item:
+      An individual gophermap item has attributes Type, Display, Selector, Hostname, and Port, and can re-serialize itself into a gophermap CRLF-terminated line with the String() method.
+`
+
+const formats = `Inputs:
+  gemtext
+  gophermap
+
+Outputs:
+  markdown
+  html
+  atom (with gemtext input only)
+`
+
+func main() {
+	conf := configure()
+
+	tover, hover, err := overrides(conf)
+	if err != nil {
+		fail("template loading failed")
+	}
+
+	switch conf.input + "-" + conf.output {
+	case "gemtext-markdown":
+		doc, err := gemtext.Parse(os.Stdin)
+		if err != nil {
+			fail("gemtext reading failed")
+		}
+		if err := gem_mdconv.Convert(os.Stdout, doc, tover); err != nil {
+			fail("markdown writing failed")
+		}
+	case "gemtext-html":
+		doc, err := gemtext.Parse(os.Stdin)
+		if err != nil {
+			fail("gemtext reading failed")
+		}
+		if err := gem_htmlconv.Convert(os.Stdout, doc, hover); err != nil {
+			fail("html writing failed")
+		}
+	case "gemtext-atom":
+		u, err := url.Parse(conf.location)
+		if conf.location == "" || err != nil {
+			fail("-l|--location must be provided and valid for gemtext to atom conversion")
+		}
+		doc, err := gemtext.Parse(os.Stdin)
+		if err != nil {
+			fail("gemtext reading failed")
+		}
+		if err := atomconv.Convert(os.Stdout, doc, u); err != nil {
+			fail("atom writing failed")
+		}
+	case "gophermap-markdown":
+		doc, err := gophermap.Parse(os.Stdin)
+		if err != nil {
+			fail("gophermap reading failed")
+		}
+		if err := goph_mdconv.Convert(os.Stdout, doc, tover); err != nil {
+			fail("markdown wriiting failed")
+		}
+	case "gophermap-html":
+		doc, err := gophermap.Parse(os.Stdin)
+		if err != nil {
+			fail("gophermap reading failed")
+		}
+		if err := goph_htmlconv.Convert(os.Stdout, doc, hover); err != nil {
+			fail("html writing failed")
+		}
+	default:
+		os.Stderr.WriteString("unsupported input/output combination\n")
+		fail(formats)
+	}
+}
+
+type config struct {
+	input    string
+	output   string
+	location string
+	template []string
+}
+
+func configure() config {
+	conf := config{}
+
+	for i := 1; i < len(os.Args); i += 1 {
+		switch os.Args[i] {
+		case "-h", "--help":
+			os.Stdout.WriteString(usage)
+			os.Exit(0)
+		case "--list-formats":
+			os.Stdout.WriteString(formats)
+			os.Exit(0)
+		case "-i", "--input":
+			if i == len(os.Args) {
+				fail(usage)
+			}
+			i += 1
+			conf.input = os.Args[i]
+		case "-o", "--output":
+			if i == len(os.Args) {
+				fail(usage)
+			}
+			i += 1
+			conf.output = os.Args[i]
+		case "-l", "--location":
+			if i == len(os.Args) {
+				fail(usage)
+			}
+			i += 1
+			conf.location = os.Args[i]
+		case "-t", "--template":
+			if i == len(os.Args) {
+				fail(usage)
+			}
+			i += 1
+			conf.template = append(conf.template, os.Args[i])
+		}
+	}
+
+	if conf.input == "" || conf.output == "" {
+		fail("both -i|--input and -o|--output are required\n")
+	}
+
+	return conf
+}
+
+func overrides(conf config) (*template.Template, *htemplate.Template, error) {
+	if len(conf.template) == 0 {
+		return nil, nil, nil
+	}
+
+	switch conf.output {
+	case "markdown":
+		tmpl, err := template.New("mdconv").ParseFiles(conf.template...)
+		if err != nil {
+			return nil, nil, err
+		}
+		return tmpl, nil, nil
+
+	case "html":
+		tmpl, err := htemplate.New("htmlconv").ParseFiles(conf.template...)
+		if err != nil {
+			return nil, nil, err
+		}
+		return nil, tmpl, err
+	}
+
+	return nil, nil, nil
+}
+
+func fail(msg string) {
+	os.Stderr.WriteString(msg)
+	os.Exit(1)
+}