feat: make invite link base URL configurable via APP_URL

Load environment variables from .env file using godotenv.
Defaults to https://demo.adriatica.io if APP_URL is not set.

.env.example

@@ -0,0 +1,5 @@
+# Application URL for invite links (defaults to https://demo.adriatica.io)
+# APP_URL=http://localhost:7331
+
+# Server port (defaults to 7331)
+# PORT=7331

.gitignore

@@ -1,6 +1,7 @@
 c4
 c4.db
 data/
+.env
 
 # Deploy artifacts
 c4-deploy-*.tar.gz

go.mod

@@ -4,10 +4,10 @@ go 1.25.4
 
 require (
 	github.com/google/uuid v1.6.0
+	github.com/joho/godotenv v1.5.1
 	github.com/pressly/goose/v3 v3.26.0
 	github.com/ryanhamamura/via v0.4.0
 	golang.org/x/crypto v0.47.0
-	maragu.dev/gomponents v1.2.0
 	modernc.org/sqlite v1.44.0
 )
 
@@ -43,6 +43,7 @@ require (
 	golang.org/x/sync v0.18.0 // indirect
 	golang.org/x/sys v0.40.0 // indirect
 	golang.org/x/time v0.14.0 // indirect
+	maragu.dev/gomponents v1.2.0 // indirect
 	modernc.org/libc v1.67.4 // indirect
 	modernc.org/mathutil v1.7.1 // indirect
 	modernc.org/memory v1.11.0 // indirect

go.sum

@@ -33,6 +33,8 @@ github.com/hashicorp/golang-lru/v2 v2.0.7 h1:a+bsQ5rvGLjzHuww6tVxozPZFVghXaHOwFs
 github.com/hashicorp/golang-lru/v2 v2.0.7/go.mod h1:QeFd9opnmA6QUJc5vARoKUSoFhyfM2/ZepoAG6RGpeM=
 github.com/hookenz/gotailwind/v4 v4.1.18 h1:1h3XwTVx1dEBm6A0bcosAplNCde+DCmVJG0arLy5fBE=
 github.com/hookenz/gotailwind/v4 v4.1.18/go.mod h1:IfiJtdp8ExV9HV2XUiVjRBvB3QewVXVKWoAGEcpjfNE=
+github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
+github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
 github.com/klauspost/compress v1.16.7/go.mod h1:ntbaceVETuRiXiv4DpjP66DpAtAGkEQskQzEyD//IeE=
 github.com/klauspost/compress v1.18.2 h1:iiPHWW0YrcFgpBYhsA6D1+fqHssJscY/Tm/y2Uqnapk=
 github.com/klauspost/compress v1.18.2/go.mod h1:R0h/fSBs8DE4ENlcrlib3PsXS61voFxhIs2DeRhCvJ4=

main.go

@@ -9,6 +9,7 @@ import (
 	"os"
 
 	"github.com/google/uuid"
+	"github.com/joho/godotenv"
 
 	"github.com/ryanhamamura/c4/auth"
 	"github.com/ryanhamamura/c4/db"
@@ -46,6 +47,8 @@ func port() string {
 }
 
 func main() {
+	_ = godotenv.Load()
+
 	if err := db.Init("c4.db"); err != nil {
 		log.Fatal(err)
 	}

ui/snakestatus.go

@@ -130,7 +130,7 @@ func SnakePlayerList(sg *snake.SnakeGame, mySlot int) h.H {
 }
 
 func SnakeInviteLink(gameID string) h.H {
-	fullURL := baseURL + "/snake/" + gameID
+	fullURL := getBaseURL() + "/snake/" + gameID
 	return h.Div(h.Class("mt-4 text-center"),
 		h.P(h.Text("Share this link to invite players:")),
 		h.Div(h.Class("bg-base-200 p-4 rounded-lg font-mono break-all my-2"),

ui/status.go

@@ -1,6 +1,8 @@
 package ui
 
 import (
+	"os"
+
 	"github.com/ryanhamamura/c4/game"
 	"github.com/ryanhamamura/via/h"
 )
@@ -115,10 +117,15 @@ func PlayerInfo(g *game.Game, myColor int) h.H {
 	)
 }
 
-const baseURL = "https://demo.adriatica.io"
+func getBaseURL() string {
+	if url := os.Getenv("APP_URL"); url != "" {
+		return url
+	}
+	return "https://demo.adriatica.io"
+}
 
 func InviteLink(gameID string) h.H {
-	fullURL := baseURL + "/game/" + gameID
+	fullURL := getBaseURL() + "/game/" + gameID
 	return h.Div(h.Class("mt-4 text-center"),
 		h.P(h.Text("Share this link with your opponent:")),
 		h.Div(h.Class("bg-base-200 p-4 rounded-lg font-mono break-all my-2"),