Add support for shortcode-like feature in posts

admin-app/post.go

@@ -2,8 +2,11 @@ package admin_app
 
 import (
 	"encoding/json"
+	"fmt"
 	"net/http"
+	"regexp"
 	"strconv"
+	"strings"
 
 	"github.com/gin-gonic/gin"
 	"github.com/matheusgomes28/urchin/database"
@@ -65,10 +68,20 @@ func postPostHandler(database database.Database) func(*gin.Context) {
 			return
 		}
 
+		transformed_content, err := transformContent(add_post_request.Content)
+		if err != nil {
+			log.Warn().Msgf("could not transform post: %v", err)
+			c.JSON(http.StatusBadRequest, gin.H{
+				"error": "invalid request body",
+				"msg":   err.Error(),
+			})
+			return
+		}
+
 		id, err := database.AddPost(
 			add_post_request.Title,
 			add_post_request.Excerpt,
-			add_post_request.Content,
+			transformed_content,
 		)
 		if err != nil {
 			log.Error().Msgf("failed to add post: %v", err)
@@ -153,3 +166,66 @@ func deletePostHandler(database database.Database) func(*gin.Context) {
 		})
 	}
 }
+
+// partitionString will partition the strings by
+// removing the given ranges
+func partitionString(text string, indexes [][]int) []string {	
+
+	partitions := make([]string, 0)
+	start := 0
+	for _, window := range indexes {
+		partitions = append(partitions, text[start:window[0]])
+		start = window[1]
+	}
+
+	partitions = append(partitions, text[start:len(text)-1])
+	return partitions
+}
+
+func shortcodeToMarkdown(shortcode string) (string, error) {
+	key_value := strings.Split(shortcode, ":")
+
+	key := key_value[0]
+	values := key_value[1:]
+
+	if key == "img" {
+		if len(values) == 1 {
+			image_src := fmt.Sprintf("/media/%s", values[0])
+			return fmt.Sprintf("![image](%s)", image_src), nil
+		} else if len(values) == 2 {
+			image_src := fmt.Sprintf("/media/%s", values[0])
+			alt_text :=  values[1]
+			return fmt.Sprintf("![%s](%s)", alt_text, image_src), nil
+		} else {
+			return "", fmt.Errorf("invalid shortcode: %s", shortcode)
+		}
+	}
+
+	return "", fmt.Errorf("unsupported shortcode: %s", key)
+}
+
+func transformContent(content string) (string, error) {
+	// Find all the occurences of {{ and }}
+	regex, _ := regexp.Compile(`{{[\w.-]+(:[\w.-]+)+}}`)
+
+	shortcodes := regex.FindAllStringIndex(content, -1)
+	partitions := partitionString(content, shortcodes)
+
+	builder := strings.Builder{}
+	i := 0
+	for i, shortcode := range(shortcodes) {
+		builder.WriteString(partitions[i])
+
+		markdown, err := shortcodeToMarkdown(content[shortcode[0]+2:shortcode[1]-2])
+		if err != nil {
+			return "", err
+		}
+		builder.WriteString(markdown)
+	}
+
+	// Guaranteed to have +1 than the number of
+	// shortcodes by algorithm
+	builder.WriteString(partitions[i+1])
+
+	return builder.String(), nil
+}

app/app.go

@@ -30,6 +30,7 @@ func SetupRoutes(app_settings common.AppSettings, database database.Database) *g
 	r.POST("/contact-send", makeContactFormHandler())
 
 	r.Static("/static", "./static")
+	r.Static("/media", "./media")
 	return r
 }