Implemented headers and paragraphs

Render.go

@@ -1,6 +1,71 @@
 package markdown
 
+import (
+	"html"
+	"strings"
+)
+
+var (
+	headerStart = []string{"<h1>", "<h2>", "<h3>", "<h4>", "<h5>", "<h6>"}
+	headerEnd   = []string{"</h1>", "</h2>", "</h3>", "</h4>", "</h5>", "</h6>"}
+)
+
 // Render creates HTML from the supplied markdown text.
 func Render(markdown string) string {
-	return ""
+	var (
+		out       = strings.Builder{}
+		paragraph = strings.Builder{}
+		i         = 0
+		lineStart = 0
+	)
+
+	flush := func() {
+		if paragraph.Len() == 0 {
+			return
+		}
+
+		out.WriteString("<p>")
+		out.WriteString(html.EscapeString(paragraph.String()))
+		out.WriteString("</p>")
+		paragraph.Reset()
+	}
+
+	for {
+		if i > len(markdown) {
+			flush()
+			return out.String()
+		}
+
+		if i != len(markdown) && markdown[i] != '\n' {
+			i++
+			continue
+		}
+
+		line := markdown[lineStart:i]
+		lineStart = i + 1
+		i++
+
+		switch {
+		case strings.HasPrefix(line, "#"):
+			flush()
+			space := strings.IndexByte(line, ' ')
+
+			if space > 0 && space <= 6 {
+				out.WriteString(headerStart[space-1])
+				out.WriteString(html.EscapeString(line[space+1:]))
+				out.WriteString(headerEnd[space-1])
+			}
+
+		default:
+			if len(line) == 0 {
+				continue
+			}
+
+			if paragraph.Len() > 0 {
+				paragraph.WriteByte(' ')
+			}
+
+			paragraph.WriteString(line)
+		}
+	}
 }