package main

// The two filters: in process for the forge's pages, as programs for cgit.

import (
	"bytes"
	"fmt"
	"html/template"
	"io"
	"log"
	"os"
	"os/exec"
	"path"

	"github.com/yuin/goldmark"
)

// Raw HTML is left unrendered, goldmark's default, which is what makes user
// text safe to hand it.
var markdown = goldmark.New()

func renderMarkdown(source string) template.HTML {
	var buf bytes.Buffer
	if err := markdown.Convert([]byte(source), &buf); err != nil {
		log.Printf("markdown: %v", err)
		return template.HTML(template.HTMLEscapeString(source))
	}
	return template.HTML(buf.String())
}

// runMarkdown is the about-filter: markdown on stdin, HTML on stdout.
func runMarkdown() int {
	source, err := io.ReadAll(os.Stdin)
	if err != nil {
		fmt.Fprintln(os.Stderr, "md:", err)
		return 1
	}
	if err := markdown.Convert(source, os.Stdout); err != nil {
		// A readable page beats an empty one.
		fmt.Fprintln(os.Stderr, "md:", err)
		template.HTMLEscape(os.Stdout, source)
		return 1
	}
	return 0
}

// runHighlight is the source-filter: cgit's bundled one issues a command line
// the installed highlight refuses, silently.
func runHighlight(args []string) int {
	source, err := io.ReadAll(os.Stdin)
	if err != nil {
		fmt.Fprintln(os.Stderr, "highlight:", err)
		return 1
	}
	name := "source"
	if len(args) > 0 && args[0] != "" {
		name = path.Base(args[0])
	}
	// --force: an unknown syntax comes back as escaped text, not as nothing.
	cmd := exec.Command("highlight", "--fragment", "--force", "--out-format=html", "--syntax-by-name="+name)
	cmd.Stdin = bytes.NewReader(source)
	cmd.Stderr = os.Stderr
	out, err := cmd.Output()
	if err != nil || len(bytes.TrimSpace(out)) == 0 {
		if err != nil {
			fmt.Fprintln(os.Stderr, "highlight:", err)
		}
		template.HTMLEscape(os.Stdout, source)
		return 0
	}
	os.Stdout.Write(out)
	return 0
}