Add support for shortcode-like feature in posts

admin-app/app.go

@@ -4,6 +4,7 @@ import (
 	"github.com/gin-gonic/gin"
 	"github.com/matheusgomes28/urchin/common"
 	"github.com/matheusgomes28/urchin/database"
+	lua "github.com/yuin/gopher-lua"
 )
 
 type PostBinding struct {
@@ -27,13 +28,13 @@ type DeletePostRequest struct {
 	Id int `json:"id"`
 }
 
-func SetupRoutes(app_settings common.AppSettings, database database.Database) *gin.Engine {
+func SetupRoutes(app_settings common.AppSettings, database database.Database, shortcode_handlers map[string]*lua.LState) *gin.Engine {
 
 	r := gin.Default()
 	r.MaxMultipartMemory = 1
 
 	r.GET("/posts/:id", getPostHandler(database))
-	r.POST("/posts", postPostHandler(database))
+	r.POST("/posts", postPostHandler(database, shortcode_handlers))
 	r.PUT("/posts", putPostHandler(database))
 	r.DELETE("/posts", deletePostHandler(database))
 

admin-app/post.go

@@ -2,12 +2,16 @@ package admin_app
 
 import (
 	"encoding/json"
+	"fmt"
 	"net/http"
+	"regexp"
 	"strconv"
+	"strings"
 
 	"github.com/gin-gonic/gin"
 	"github.com/matheusgomes28/urchin/database"
 	"github.com/rs/zerolog/log"
+	lua "github.com/yuin/gopher-lua"
 )
 
 func getPostHandler(database database.Database) func(*gin.Context) {
@@ -50,7 +54,7 @@ func getPostHandler(database database.Database) func(*gin.Context) {
 	}
 }
 
-func postPostHandler(database database.Database) func(*gin.Context) {
+func postPostHandler(database database.Database, shortcode_handlers map[string]*lua.LState) func(*gin.Context) {
 	return func(c *gin.Context) {
 		var add_post_request AddPostRequest
 		decoder := json.NewDecoder(c.Request.Body)
@@ -65,10 +69,20 @@ func postPostHandler(database database.Database) func(*gin.Context) {
 			return
 		}
 
+		transformed_content, err := transformContent(add_post_request.Content, shortcode_handlers)
+		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 +167,77 @@ 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, shortcode_handlers map[string]*lua.LState) (string, error) {
+	key_value := strings.Split(shortcode, ":")
+
+	key := key_value[0]
+	values := key_value[1:]
+
+	if handler, found := shortcode_handlers[key]; found {
+
+		// Need to quote all values for a valid lua syntax
+		quoted_values := make([]string, 0)
+		for _, value := range values {
+			quoted_values = append(quoted_values, fmt.Sprintf("%q", value))
+		}
+
+		err := handler.DoString(fmt.Sprintf(`result = HandleShortcode({%s})`, strings.Join(quoted_values, ",")))
+		if err != nil {
+			return "", fmt.Errorf("error running %s shortcode: %v", key, err)
+		}
+
+		value := handler.GetGlobal("result")
+		if ret_type := value.Type().String(); ret_type != "string" {
+			return "", fmt.Errorf("error running %s shortcode: invalid return type %s", key, ret_type)
+		} else if ret_type == "" {
+			return "", fmt.Errorf("error running %s shortcode: returned empty string", key)
+		}
+
+		return value.String(), nil
+	}
+
+	return "", fmt.Errorf("unsupported shortcode: %s", key)
+}
+
+func transformContent(content string, shortcode_handlers map[string]*lua.LState) (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], shortcode_handlers)
+		if err != nil {
+			log.Error().Msgf("%v", err)
+			markdown = ""
+		}
+		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
 }
 

cmd/urchin-admin/main.go

@@ -10,8 +10,26 @@ import (
 	"github.com/matheusgomes28/urchin/common"
 	"github.com/matheusgomes28/urchin/database"
 	"github.com/rs/zerolog/log"
+	lua "github.com/yuin/gopher-lua"
 )
 
+func loadShortcodeHandlers(shortcodes []common.Shortcode) (map[string]*lua.LState, error) {
+	shortcode_handlers := make(map[string]*lua.LState, 0)
+	for _, shortcode := range shortcodes {
+		// Read the LUA state
+		state := lua.NewState()
+		err := state.DoFile(shortcode.Plugin)
+		// TODO : check that the function HandleShortcode(args)
+		//        exists and returns the correct type
+		if err != nil {
+			return map[string]*lua.LState{}, fmt.Errorf("could not load shortcode %s: %v", shortcode.Name, err)
+		}
+		shortcode_handlers[shortcode.Name] = state
+	}
+
+	return shortcode_handlers, nil
+}
+
 func main() {
 	// sets zerolog as the main logger
 	// in this APP
@@ -51,7 +69,13 @@ func main() {
 		os.Exit(-1)
 	}
 
-	r := admin_app.SetupRoutes(app_settings, database)
+	shortcode_handlers, err := loadShortcodeHandlers(app_settings.Shortcodes)
+	if err != nil {
+		log.Error().Msgf("%v", err)
+		os.Exit(-1)
+	}
+
+	r := admin_app.SetupRoutes(app_settings, database, shortcode_handlers)
 	err = r.Run(fmt.Sprintf(":%d", app_settings.WebserverPort))
 	if err != nil {
 		log.Error().Msgf("could not run app: %v", err)

common/app_settings.go

@@ -8,14 +8,22 @@ import (
 	"github.com/BurntSushi/toml"
 )
 
+type Shortcode struct {
+	// name for the shortcode {{name:...:...}}
+	Name string `toml:"name"`
+	// The lua plugin path
+	Plugin string `toml:"plugin"`
+}
+
 type AppSettings struct {
-	DatabaseAddress  string `toml:"database_address"`
-	DatabasePort     int    `toml:"database_port"`
-	DatabaseUser     string `toml:"database_user"`
-	DatabasePassword string `toml:"database_password"`
-	DatabaseName     string `toml:"database_name"`
-	WebserverPort    int    `toml:"webserver_port"`
-	ImageDirectory   string `toml:"image_dir"`
+	DatabaseAddress  string      `toml:"database_address"`
+	DatabasePort     int         `toml:"database_port"`
+	DatabaseUser     string      `toml:"database_user"`
+	DatabasePassword string      `toml:"database_password"`
+	DatabaseName     string      `toml:"database_name"`
+	WebserverPort    int         `toml:"webserver_port"`
+	ImageDirectory   string      `toml:"image_dir"`
+	Shortcodes       []Shortcode `toml:"shortcodes"`
 }
 
 func LoadSettings() (AppSettings, error) {

common/app_settings_test.go

@@ -35,6 +35,7 @@ func TestCorrectToml(t *testing.T) {
 		DatabaseName:     "test_database_name",
 		WebserverPort:    99999,
 		DatabasePort:     666,
+		Shortcodes:       []Shortcode{},
 	}
 	bytes, err := toml.Marshal(expected)
 	assert.Nil(t, err)
@@ -50,17 +51,19 @@ func TestCorrectToml(t *testing.T) {
 func TestMissingDatabaseAddress(t *testing.T) {
 
 	missing_database_address := struct {
-		DatabaseUser     string `toml:"database_user"`
-		DatabasePassword string `toml:"database_password"`
-		DatabaseName     string `toml:"database_name"`
-		WebserverPort    string `toml:"webserver_port"`
-		DatabasePort     string `toml:"database_port"`
+		DatabaseUser     string      `toml:"database_user"`
+		DatabasePassword string      `toml:"database_password"`
+		DatabaseName     string      `toml:"database_name"`
+		WebserverPort    string      `toml:"webserver_port"`
+		DatabasePort     string      `toml:"database_port"`
+		Shortcodes       []Shortcode `toml:"shortcodes"`
 	}{
 		DatabaseUser:     "test_database_user",
 		DatabasePassword: "test_database_password",
 		DatabaseName:     "test_database_name",
 		WebserverPort:    "99999",
 		DatabasePort:     "666",
+		Shortcodes:       []Shortcode{},
 	}
 
 	bytes, err := toml.Marshal(missing_database_address)

go.mod

@@ -35,6 +35,7 @@ require (
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/twitchyliquid64/golang-asm v0.15.1 // indirect
 	github.com/ugorji/go/codec v1.2.11 // indirect
+	github.com/yuin/gopher-lua v1.1.1 // indirect
 	golang.org/x/arch v0.3.0 // indirect
 	golang.org/x/crypto v0.14.0 // indirect
 	golang.org/x/net v0.17.0 // indirect

go.sum

@@ -83,6 +83,8 @@ github.com/twitchyliquid64/golang-asm v0.15.1 h1:SU5vSMR7hnwNxj24w34ZyCi/FmDZTkS
 github.com/twitchyliquid64/golang-asm v0.15.1/go.mod h1:a1lVb/DtPvCB8fslRZhAngC2+aY1QWCk3Cedj/Gdt08=
 github.com/ugorji/go/codec v1.2.11 h1:BMaWp1Bb6fHwEtbplGBGJ498wD+LKlNSl25MjdZY4dU=
 github.com/ugorji/go/codec v1.2.11/go.mod h1:UNopzCgEMSXjBc6AOMqYvWC1ktqTAfzJZUZgYf6w6lg=
+github.com/yuin/gopher-lua v1.1.1 h1:kYKnWBjvbNP4XLT3+bPEwAXJx262OhaHDWDVOPjL46M=
+github.com/yuin/gopher-lua v1.1.1/go.mod h1:GBR0iDaNXjAgGg9zfCvksxSRnQx76gclCIb7kdAd1Pw=
 github.com/zutto/shardedmap v0.0.0-20180201164343-415202d0910e h1:zqDzvgPMqbfHrSXOo2igl2H9q2RoY5l7z1YpaPGMuog=
 github.com/zutto/shardedmap v0.0.0-20180201164343-415202d0910e/go.mod h1:NKD0ezOo5cN3cWU7CGigl5LQhm3gNi+jaOplrVspLjc=
 golang.org/x/arch v0.0.0-20210923205945-b76863e36670/go.mod h1:5om86z9Hs0C8fWVUuoMHwpExlXzs5Tkyp9hOrfG7pp8=

plugins/image_shortcode.lua

@@ -0,0 +1,11 @@
+function HandleShortcode(arguments)
+    if #arguments == 1 then
+        local image_src = string.format("/media/%s", arguments[1])
+        return string.format("![image](%s)", image_src)
+    elseif #arguments == 2 then
+        local image_src = string.format("/media/%s", arguments[1])
+        return string.format("![%s](%s)", arguments[2], image_src)
+    else
+        return ""
+    end
+end

plugins/table_shortcode.lua

@@ -0,0 +1,7 @@
+function HandleShortcode(arguments)
+    if #arguments ~= 2 then
+        return ""
+    end
+
+    return "\n| Tables   |      Are      |  Cool |\n|----------|:-------------:|------:|\n| col 1 is |  left-aligned | $1600 |\n| col 2 is |    centered   |   $12 |\n| col 3 is | right-aligned |    $1 |\n"
+end

urchin_config.toml

@@ -1,5 +1,5 @@
 # Address to the MariaDB database
-database_address = "mariadb"
+database_address = "localhost"
 
 # User to access datbaase
 database_user = "root"
@@ -12,7 +12,17 @@ database_port = 3306
 
 # name of database where urchin's
 # migrations was installed
-database_name = "urchin"
+database_name = "gocms"
 
 # port to run the webserver on
 webserver_port = 8080
+
+[[shortcodes]]
+name = "img"
+# must have function "HandleShortcode(arguments []string) -> string"
+plugin = "plugins/image_shortcode.lua"
+
+[[shortcodes]]
+name = "table"
+# must have function "HandleShortcode(arguments []string) -> string"
+plugin = "plugins/table_shortcode.lua"