From 296274ac60f89352d3e7e1e40e1f88a74a128a61 Mon Sep 17 00:00:00 2001
From: Runxi Yu <me@runxiyu.org>
Date: Tue, 1 Oct 2024 19:32:50 +0800
Subject: wsm.go, main.js: Display the user's selected courses on first run

It's done in the WebSocket routines rather than in the template maker
because it's relatively easier to write the logic this way.
---
 static/main.js |  4 ++++
 wsm.go         | 20 ++++++++++++++++++--
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/static/main.js b/static/main.js
index c5c4cbb..3fc1cb0 100644
--- a/static/main.js
+++ b/static/main.js
@@ -50,6 +50,10 @@ socket.addEventListener("open", function() {
 			document.querySelectorAll(".before-connection").forEach(c => {
 				c.style.display = "none"
 			})
+			let courseIDs = mar[1].split(",")
+			for (let i = 0; i < courseIDs.length; i++) {
+				document.getElementById(`tick${ courseIDs[i] }`).checked = true
+			}
 			break
 		case "U": /* unauthenticated */
 			/* TODO: replace this with a box on screen */
diff --git a/wsm.go b/wsm.go
index c00ff32..a0525b3 100644
--- a/wsm.go
+++ b/wsm.go
@@ -25,6 +25,7 @@ import (
 	"errors"
 	"fmt"
 	"strconv"
+	"strings"
 	"time"
 
 	"github.com/coder/websocket"
@@ -33,11 +34,26 @@ import (
 )
 
 func messageHello(ctx context.Context, c *websocket.Conn, mar []string, userID string, session string) error {
-	_, _, _ = mar, userID, session
-	err := writeText(ctx, c, "HI")
+	_, _ = mar, session
+
+	rows, err := db.Query(
+		ctx,
+		"SELECT courseid FROM choices WHERE userid = $1",
+		userID,
+	)
+	if err != nil {
+		return protocolError(ctx, c, "error fetching choices")
+	}
+	courseIDs, err := pgx.CollectRows(rows, pgx.RowTo[string])
+	if err != nil {
+		return protocolError(ctx, c, "error collecting choices")
+	}
+
+	err = writeText(ctx, c, "HI :"+strings.Join(courseIDs, ","))
 	if err != nil {
 		return fmt.Errorf("error replying to HELLO: %w", err)
 	}
+
 	return nil
 }
 
-- 
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