Add HTML generation

1 files changed, 105 insertions, 0 deletions

diff --git a/transformations.go b/transformations.go
new file mode 100644
index 0000000..7053a94
--- /dev/null
+++ b/transformations.go
@@ -0,0 +1,105 @@
+// Copyright (c) 2023 Nicolas Paul All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"log"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/gomarkdown/markdown"
+	"github.com/gomarkdown/markdown/html"
+	"github.com/gomarkdown/markdown/parser"
+)
+
+// TransformMarkdownFile simply copy a non-markdown file to the output
+// directory.
+func TransformNonMarkdownFile(inputDir, inputFile, outputDir string) error {
+	inputPath := filepath.Join(inputDir, inputFile)
+
+	input, err := os.ReadFile(inputPath)
+	if err != nil {
+		return err
+	}
+
+	outputPath := filepath.Join(outputDir, inputFile)
+	if err := os.WriteFile(outputPath, input, 0666); err != nil {
+		return err
+	}
+
+	log.Printf("copied file %q to %q", inputPath, outputPath)
+
+	return nil
+}
+
+// TransformDirectory creates a directory in the output directory.
+func TransformDirectory(inputDir, inputFile, outputDir string) error {
+	outputPath := filepath.Join(outputDir, inputFile)
+
+	if err := os.MkdirAll(outputPath, 0777); err != nil {
+		return err
+	}
+
+	log.Printf("created directory %q", outputPath)
+
+	return nil
+}
+
+// TransformMarkdownFile generates the corresponding HTML document from a
+// Markdown file.
+func TransformMarkdownFile(inputDir, inputFile, outputDir string) error {
+	inputPath := filepath.Join(inputDir, inputFile)
+
+	// The output file is the same as the input file, but with a different
+	// extension.
+	fn := strings.TrimSuffix(inputFile, filepath.Ext(inputFile)) + ".html"
+	outputPath := filepath.Join(outputDir, fn)
+
+	contentRaw, err := os.ReadFile(inputPath)
+	if err != nil {
+		return err
+	}
+
+	// Parse front matter
+	fm, contentMD, err := ParseFrontMatter(contentRaw)
+	if err != nil {
+		return err
+	}
+
+	// Skip hidden files unless -hidden is specified
+	if fm.Hide && !*generateHidden {
+		log.Printf("skipped hidden file %q", inputPath)
+		return nil
+	}
+
+	// Render Markdown to HTML
+	pExtensions := parser.Tables | parser.FencedCode |
+		parser.Autolink | parser.Strikethrough | parser.SpaceHeadings |
+		parser.HeadingIDs | parser.BackslashLineBreak |
+		parser.AutoHeadingIDs | parser.Footnotes | parser.SuperSubscript |
+		parser.NoIntraEmphasis
+	p := parser.NewWithExtensions(pExtensions)
+	doc := p.Parse(contentMD)
+
+	htmlFlags := html.Smartypants | html.SmartypantsFractions |
+		html.SmartypantsDashes | html.SmartypantsLatexDashes |
+		html.HrefTargetBlank | html.LazyLoadImages
+	renderer := html.NewRenderer(html.RendererOptions{Flags: htmlFlags})
+	contentHTML := markdown.Render(doc, renderer)
+
+	outputFile, err := os.Create(outputPath)
+	if err != nil {
+		return err
+	}
+	defer outputFile.Close()
+
+	if err := GenerateHTML(outputFile, fm, string(contentHTML)); err != nil {
+		return err
+	}
+
+	log.Printf("generated file %q", outputPath)
+	return nil
+}