From eb3a072bcf3ec3f9de126e5b644bf5a0e78b32c1 Mon Sep 17 00:00:00 2001
From: Peter Stuifzand <peter@stuifzand.eu>
Date: Sun, 25 Aug 2019 15:40:56 +0200
Subject: [PATCH] Refactor renderer

---
 render.go | 266 ++++++++++++++++++++++++++++++++----------------------
 1 file changed, 160 insertions(+), 106 deletions(-)

diff --git a/render.go b/render.go
index 2f9f185..0c4e5b6 100644
--- a/render.go
+++ b/render.go
@@ -4,11 +4,18 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
+	"io"
 )
 
+type Renderer interface {
+	Render(w io.Writer) error
+}
+
 type Block struct {
 	Type string
 	Data json.RawMessage
+
+	renderer Renderer
 }
 
 type Paragraph struct {
@@ -54,118 +61,165 @@ type Document struct {
 	Blocks  []Block
 }
 
+func (block Block) getType() (Renderer, error) {
+	switch block.Type {
+	case "table":
+		return &Table{}, nil
+	case "link":
+		return &Link{}, nil
+	case "list":
+		return &List{}, nil
+	case "header":
+		return &Header{}, nil
+	case "paragraph":
+		return &Paragraph{}, nil
+	case "code":
+		return &Code{}, nil
+	case "checklist":
+		return &Checklist{}, nil
+	default:
+		return nil, fmt.Errorf("unknown type: %s", block.Type)
+	}
+}
+
+func (block Block) load() (Renderer, error) {
+	if block.renderer != nil {
+		return block.renderer, nil
+	}
+	renderer, err := block.getType()
+
+	if err != nil {
+		return nil, err
+	}
+
+	err = json.Unmarshal(block.Data, renderer)
+	if err != nil {
+		return nil, err
+	}
+
+	block.renderer = renderer
+
+	return renderer, nil
+}
+
+func (document *Document) Render(w io.Writer) error {
+	var buf bytes.Buffer
+	for _, block := range document.Blocks {
+		renderer, err := block.load()
+		if err != nil {
+			return err
+		}
+		if err = renderer.Render(&buf); err != nil {
+			return err
+		}
+	}
+	_, err := buf.WriteTo(w)
+	return err
+}
+
 func renderJSON(text string) (string, error) {
-	var data Document
-	err := json.Unmarshal([]byte(text), &data)
+	var document Document
+	err := json.Unmarshal([]byte(text), &document)
 	if err != nil {
 		return "", err
 	}
 
 	var buf bytes.Buffer
-
-	for _, block := range data.Blocks {
-		switch block.Type {
-		case "table":
-			var table Table
-			err = json.Unmarshal(block.Data, &table)
-			if err != nil {
-				return "", fmt.Errorf("error while parsing %s: %s", block.Type, err.Error())
-			}
-
-			buf.WriteString("<table class='table'>")
-			for _, row := range table.Content {
-				buf.WriteString("<tr>")
-				for _, col := range row {
-					buf.WriteString("<td>")
-					buf.WriteString(col)
-					buf.WriteString("</td>")
-				}
-				buf.WriteString("</tr>")
-			}
-			buf.WriteString("</table>")
-			break
-		case "link":
-			// TODO(peter): improve link rendering
-			var link Link
-			err = json.Unmarshal(block.Data, &link)
-			if err != nil {
-				return "", fmt.Errorf("error while parsing %s: %s", block.Type, err.Error())
-			}
-			fmt.Fprintf(&buf, `<a href=%q>%s</a>`, link.Link, link.Meta.Title)
-		case "list":
-			var list List
-			err = json.Unmarshal(block.Data, &list)
-			if err != nil {
-				return "", fmt.Errorf("error while parsing %s: %s", block.Type, err.Error())
-			}
-			var tag string
-			if list.Style == "ordered" {
-				tag = "ol"
-			} else {
-				tag = "ul"
-			}
-			buf.WriteString("<")
-			buf.WriteString(tag)
-			buf.WriteString(">")
-			for _, item := range list.Items {
-				buf.WriteString("<li>")
-				buf.WriteString(item)
-				buf.WriteString("</li>")
-			}
-			buf.WriteString("</")
-			buf.WriteString(tag)
-			buf.WriteString(">")
-		case "header":
-			var header Header
-			err = json.Unmarshal(block.Data, &header)
-			if err != nil {
-				return "", fmt.Errorf("error while parsing %s: %s", block.Type, err.Error())
-			}
-			fmt.Fprintf(&buf, "<h%d>%s</h%d>", header.Level, header.Text, header.Level)
-		case "paragraph":
-			var para Paragraph
-			err = json.Unmarshal(block.Data, &para)
-			if err != nil {
-				return "", fmt.Errorf("error while parsing %s: %s", block.Type, err.Error())
-			}
-			buf.WriteString("<p>")
-			buf.WriteString(para.Text)
-			buf.WriteString("</p>")
-		case "code":
-			var code Code
-			err = json.Unmarshal(block.Data, &code)
-			if err != nil {
-				return "", fmt.Errorf("error while parsing %s: %s", block.Type, err.Error())
-			}
-			buf.WriteString("<pre>")
-			buf.WriteString(code.Code)
-			buf.WriteString("</pre>")
-		case "checklist":
-			var checklist Checklist
-			err = json.Unmarshal(block.Data, &checklist)
-			if err != nil {
-				return "", fmt.Errorf("error while parsing %s: %s", block.Type, err.Error())
-			}
-			for _, item := range checklist.Items {
-				buf.WriteString("<p>")
-
-				buf.WriteString(`<span class="icon is-medium">`)
-				if item.Checked {
-					buf.WriteString(`  <span class="fa-stack">`)
-					buf.WriteString(`	<i class="fa fa-circle fa-stack-2x has-text-success"></i>`)
-					buf.WriteString(`	<i class="fa fa-check fa-stack-1x fa-inverse"></i>`)
-					buf.WriteString(`  </span>`)
-				}
-				buf.WriteString(`</span>`)
-				buf.WriteString(item.Text)
-				buf.WriteString("</p>")
-			}
-		default:
-			return "", fmt.Errorf("unknown type: %s", block.Type)
-		}
-
-		fmt.Fprintln(&buf)
+	err = document.Render(&buf)
+	if err != nil {
+		return "", err
 	}
-
 	return buf.String(), nil
 }
+
+func (checklist *Checklist) Render(w io.Writer) error {
+	var buf bytes.Buffer
+
+	buf.WriteString(`<div class="checklist">`)
+	for _, item := range checklist.Items {
+		buf.WriteString(`<div class="checklist--item">`)
+
+		buf.WriteString(`<span class="icon is-medium">`)
+		if item.Checked {
+			buf.WriteString(`<i class="fa fa-check-circle has-text-success"></i>`)
+		}
+		buf.WriteString(`</span>`)
+		buf.WriteString(`<div class="checklist--item-text">`)
+		buf.WriteString(item.Text)
+		buf.WriteString("</div>")
+		buf.WriteString("</div>")
+	}
+	buf.WriteString("</div>")
+	_, err := buf.WriteTo(w)
+	return err
+}
+
+func (code *Code) Render(w io.Writer) error {
+	var buf bytes.Buffer
+	buf.WriteString("<pre>")
+	buf.WriteString(code.Code)
+	buf.WriteString("</pre>")
+	_, err := buf.WriteTo(w)
+	return err
+}
+
+func (link *Link) Render(w io.Writer) error {
+	// TODO(peter): improve link rendering
+	_, err := fmt.Fprintf(w, `<a href=%q>%s</a>`, link.Link, link.Meta.Title)
+	return err
+}
+
+func (table *Table) Render(w io.Writer) error {
+	var buf bytes.Buffer
+	buf.WriteString("<table class='table'>")
+	for _, row := range table.Content {
+		buf.WriteString("<tr>")
+		for _, col := range row {
+			buf.WriteString("<td>")
+			buf.WriteString(col)
+			buf.WriteString("</td>")
+		}
+		buf.WriteString("</tr>")
+	}
+	buf.WriteString("</table>")
+	_, err := buf.WriteTo(w)
+	return err
+}
+func (list *List) Render(w io.Writer) error {
+	var buf bytes.Buffer
+
+	var tag string
+	if list.Style == "ordered" {
+		tag = "ol"
+	} else {
+		tag = "ul"
+	}
+	buf.WriteString("<")
+	buf.WriteString(tag)
+	buf.WriteString(">")
+	for _, item := range list.Items {
+		buf.WriteString("<li>")
+		buf.WriteString(item)
+		buf.WriteString("</li>")
+	}
+	buf.WriteString("</")
+	buf.WriteString(tag)
+	buf.WriteString(">")
+
+	_, err := buf.WriteTo(w)
+	return err
+}
+
+func (header *Header) Render(w io.Writer) error {
+	_, err := fmt.Fprintf(w, "<h%d>%s</h%d>", header.Level, header.Text, header.Level)
+	return err
+}
+
+func (para Paragraph) Render(w io.Writer) error {
+	var buf bytes.Buffer
+	buf.WriteString("<p>")
+	buf.WriteString(para.Text)
+	buf.WriteString("</p>")
+	_, err := buf.WriteTo(w)
+	return err
+}