fix: restore lines background with configurable color

src/main/kotlin/org/gitanimals/render/app/AnimationFacade.kt

@@ -47,19 +47,25 @@ class AnimationFacade(
         }
     }
 
-    fun getLineAnimation(username: String, personaId: Long, mode: Mode): String {
+    fun getLineAnimation(
+        username: String,
+        personaId: Long,
+        mode: Mode,
+        backgroundColor: String = "transparent",
+    ): String {
         return when (userService.existsByName(username)) {
             true -> {
                 setUserAuthInfoIfNotSet(username)
 
-                val svgAnimation = userService.getLineAnimationByUsername(username, personaId, mode)
+                val svgAnimation =
+                    userService.getLineAnimationByUsername(username, personaId, mode, backgroundColor)
                 eventPublisher.publishEvent(Visited(username, MDC.get(TRACE_ID)))
                 svgAnimation
             }
 
             false -> {
                 val user = createOrUpdateUser(username)
-                userService.getLineAnimationByUsername(user.getName(), personaId, mode)
+                userService.getLineAnimationByUsername(user.getName(), personaId, mode, backgroundColor)
             }
         }
     }

src/main/kotlin/org/gitanimals/render/controller/AnimationController.kt

@@ -32,6 +32,7 @@ class AnimationController(
         @PathVariable("username") username: String,
         @RequestParam(name = "pet-id", defaultValue = "0") personaId: String,
         @RequestParam(name = "contribution-view", defaultValue = "true") contributionView: Boolean,
+        @RequestParam(name = "background-color", defaultValue = "transparent") backgroundColor: String,
         response: HttpServletResponse,
     ): String {
         response.cacheControl(3600)
@@ -45,6 +46,7 @@ class AnimationController(
             username = username.deleteBrackets(),
             personaId = personaId.trimNotDigitCharacters().toLong(),
             mode = mode,
+            backgroundColor = backgroundColor,
         )
     }
 

src/main/kotlin/org/gitanimals/render/domain/User.kt

@@ -273,8 +273,12 @@ class User(
         visit += 1
     }
 
-    fun createLineAnimation(personaId: Long, mode: Mode): String {
-        val builder = StringBuilder().openLine()
+    fun createLineAnimation(
+        personaId: Long,
+        mode: Mode,
+        backgroundColor: String = "transparent",
+    ): String {
+        val builder = StringBuilder().openLine(backgroundColor.normalizeLineBackgroundColor())
 
         val persona = personas.find { it.id >= personaId }
             ?: throw IllegalArgumentException("Cannot find persona by id \"$personaId\"")
@@ -283,8 +287,33 @@ class User(
         return builder.closeSvg()
     }
 
-    private fun StringBuilder.openLine(): StringBuilder {
-        return this.append("<svg fill=\"none\" overflow=\"visible\" xmlns=\"http://www.w3.org/2000/svg\">")
+    private fun StringBuilder.openLine(backgroundColor: String): StringBuilder {
+        this.append("<svg fill=\"none\" overflow=\"visible\" xmlns=\"http://www.w3.org/2000/svg\">")
+
+        if (backgroundColor != "transparent") {
+            this.append("<rect width=\"100%\" height=\"100%\" fill=\"$backgroundColor\"/>")
+        }
+
+        return this
+    }
+
+    private fun String.normalizeLineBackgroundColor(): String {
+        val backgroundColor = trim()
+
+        if (backgroundColor.equals("transparent", ignoreCase = true)) {
+            return "transparent"
+        }
+
+        if (backgroundColor.equals("white", ignoreCase = true)) {
+            return "white"
+        }
+
+        val hexColor = backgroundColor.removePrefix("#")
+        require(hexColor.length in setOf(3, 4, 6, 8) && hexColor.all { it.isDigit() || it.lowercaseChar() in 'a'..'f' }) {
+            "background-color must be 'white', 'transparent', or a 3/4/6/8 digit hex color"
+        }
+
+        return "#$hexColor"
     }
 
 

src/main/kotlin/org/gitanimals/render/domain/UserService.kt

@@ -25,8 +25,13 @@ class UserService(
         return getUserByName(username).createFarmAnimation()
     }
 
-    fun getLineAnimationByUsername(username: String, personaId: Long, mode: Mode): String {
-        return getUserByName(username).createLineAnimation(personaId, mode)
+    fun getLineAnimationByUsername(
+        username: String,
+        personaId: Long,
+        mode: Mode,
+        backgroundColor: String = "transparent",
+    ): String {
+        return getUserByName(username).createLineAnimation(personaId, mode, backgroundColor)
     }
 
     @Retryable(retryFor = [ObjectOptimisticLockingFailureException::class], maxAttempts = 10)

src/test/kotlin/org/gitanimals/render/domain/UserTest.kt

@@ -129,6 +129,50 @@ internal class UserTest(
         }
     }
 
+    describe("createLineAnimation 메소드는") {
+        context("personaId와 line mode를 받으면") {
+            val personaId = 1L
+            val user = user().apply {
+                personas.add(persona(id = personaId, user = this))
+            }
+
+            it("배경색을 지정하지 않으면 기존처럼 투명 배경의 line SVG를 생성한다") {
+                val animation = user.createLineAnimation(personaId, Mode.LINE)
+
+                animation.contains("<rect width=\"100%\" height=\"100%\"") shouldBe false
+                animation.contains("<g id=\"cat-$personaId\"") shouldBe true
+            }
+
+            it("white 배경을 지정하면 흰색 배경을 포함한다") {
+                val animation = user.createLineAnimation(personaId, Mode.LINE, "white")
+
+                animation.startsWith(
+                    "<svg fill=\"none\" overflow=\"visible\" xmlns=\"http://www.w3.org/2000/svg\"><rect width=\"100%\" height=\"100%\" fill=\"white\"/>"
+                ) shouldBe true
+            }
+
+            it("hex 배경색을 지정하면 해당 색상을 포함한다") {
+                val animation = user.createLineAnimation(personaId, Mode.LINE, "0d1117")
+
+                animation.startsWith(
+                    "<svg fill=\"none\" overflow=\"visible\" xmlns=\"http://www.w3.org/2000/svg\"><rect width=\"100%\" height=\"100%\" fill=\"#0d1117\"/>"
+                ) shouldBe true
+            }
+
+            it("transparent 배경을 지정하면 배경 rect를 추가하지 않는다") {
+                val animation = user.createLineAnimation(personaId, Mode.LINE, "transparent")
+
+                animation.contains("<rect width=\"100%\" height=\"100%\"") shouldBe false
+            }
+
+            it("지원하지 않는 배경색을 지정하면 예외를 던진다") {
+                shouldThrowExactly<IllegalArgumentException> {
+                    user.createLineAnimation(personaId, Mode.LINE, "url(#malicious)")
+                }
+            }
+        }
+    }
+
     describe("mergePersona 메소드는") {
         context("increasePersonaId와 deletePersonaId를 받아서,") {
             val user = User.newUser("devxb", mapOf())