first commit! 🎉

port "ari is learning!" assets to live go backend.
some prep work for further developments for ari melody LIVE

learning/learning.go

@@ -0,0 +1,167 @@
+package learning
+
+import (
+	"context"
+	"embed"
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+	"os"
+	"strings"
+	"sync"
+	"time"
+
+	"codeberg.org/arimelody/ari-is-learning/broadcast"
+	"github.com/gin-gonic/gin"
+)
+
+//go:embed public
+var publicFS embed.FS
+//go:embed pages
+var pagesFS embed.FS
+
+type (
+	ServiceConfig struct {
+		TitleFilePath string
+	}
+
+	Service struct {
+		cfg ServiceConfig
+
+		ctx context.Context
+		titleFileMutex sync.Mutex
+		titleLastModTime time.Time
+		titleText string
+		titleUpdated chan string
+		titleUpdatedBroadcast broadcast.BroadcastChannel[string]
+	}
+)
+
+func New(ctx context.Context, cfg ServiceConfig) *Service {
+	titleUpdated := make(chan string)
+
+	if _, err := os.Stat(cfg.TitleFilePath); os.IsNotExist(err) {
+		log.Printf("Learning title file [%s] does not exist, creating one...", cfg.TitleFilePath)
+		os.WriteFile(cfg.TitleFilePath, []byte("Untitled"), 0644)
+	} else if err != nil {
+		log.Fatalf("Failed to stat title file: %v", err)
+	}
+
+	srv := &Service{
+		cfg: cfg,
+		ctx: ctx,
+		titleFileMutex: sync.Mutex{},
+		titleLastModTime: time.Unix(0, 0),
+		titleText: "",
+		titleUpdated: titleUpdated,
+		titleUpdatedBroadcast: broadcast.NewBroadcastChannel(ctx, titleUpdated),
+	}
+
+	return srv
+}
+
+func (srv *Service) BindRoutes(group *gin.RouterGroup) {
+	group.GET("/public/*path", func(ctx *gin.Context) {
+		path := strings.TrimPrefix(ctx.Request.URL.Path, "/learning/")
+		http.ServeFileFS(ctx.Writer, ctx.Request, publicFS, path)
+	})
+
+	group.GET("/sse", func(ctx *gin.Context) {
+		ctx.Header("connection", "keep-alive")
+
+		ctx.SSEvent("title-update", srv.titleText)
+
+		titleUpdated := srv.titleUpdatedBroadcast.Subscribe()
+
+		ticker := time.NewTicker(10 * time.Millisecond)
+		ctx.Stream(func(w io.Writer) bool {
+			select {
+			case titleText := <-titleUpdated:
+				ctx.SSEvent("title-update", titleText)
+			case <-ticker.C:
+			}
+			return true
+		})
+
+		srv.titleUpdatedBroadcast.Cancel(titleUpdated)
+	})
+
+	group.POST("/title", func(ctx *gin.Context) {
+		data, err := io.ReadAll(ctx.Request.Body)
+		if err != nil {
+			log.Printf("Failed to read request body: %v", err)
+			ctx.String(http.StatusInternalServerError, http.StatusText(http.StatusInternalServerError))
+			return
+		}
+		log.Printf("Waiting on title file lock...")
+		srv.titleFileMutex.Lock()
+		defer srv.titleFileMutex.Unlock()
+		log.Printf("Got it!")
+		file, err := os.OpenFile(srv.cfg.TitleFilePath, os.O_RDWR | os.O_CREATE | os.O_TRUNC, 0)
+		if err != nil {
+			log.Printf("Failed to open title file: %v", err)
+			ctx.String(http.StatusInternalServerError, http.StatusText(http.StatusInternalServerError))
+			return
+		}
+		if _, err := file.Write(data); err != nil {
+			log.Printf("Failed to write to title file: %v", err)
+			ctx.String(http.StatusInternalServerError, http.StatusText(http.StatusInternalServerError))
+			return
+		}
+
+		ctx.String(http.StatusOK, http.StatusText(http.StatusOK))
+	})
+
+	group.GET("/hello", func(ctx *gin.Context) {
+		http.ServeFileFS(ctx.Writer, ctx.Request, pagesFS, "pages/index.html")
+	})
+	group.GET("/brb", func(ctx *gin.Context) {
+		http.ServeFileFS(ctx.Writer, ctx.Request, pagesFS, "pages/brb.html")
+	})
+	group.GET("/bye", func(ctx *gin.Context) {
+		http.ServeFileFS(ctx.Writer, ctx.Request, pagesFS, "pages/bye.html")
+	})
+}
+
+func (srv *Service) Run(ctx context.Context) {
+	failed := make(chan error)
+
+	go func() {
+		for {
+			srv.titleFileMutex.Lock()
+			stat, err := os.Stat(srv.cfg.TitleFilePath)
+			if err != nil {
+				failed<-fmt.Errorf("Failed to stat title file: %v", err)
+				return
+			}
+
+			if srv.titleLastModTime.Before(stat.ModTime()) {
+				data, err := os.ReadFile(srv.cfg.TitleFilePath)
+				if err != nil {
+					failed<-fmt.Errorf("Failed to read title file: %v", err)
+					return
+				}
+
+				log.Printf(
+					"title updated: \"%s\" -> \"%s\"",
+					srv.titleText,
+					strings.TrimSpace(string(data)),
+				)
+
+				srv.titleText = strings.TrimSpace(string(data))
+				if !srv.titleLastModTime.IsZero() { srv.titleUpdated<-srv.titleText }
+				srv.titleLastModTime = stat.ModTime()
+			}
+			srv.titleFileMutex.Unlock()
+
+			time.Sleep(100 * time.Millisecond)
+		}
+	}()
+
+	select {
+	case err := <-failed:
+		log.Fatalf("Learning service error: %v", err)
+	case <-ctx.Done():
+	}
+}