feat(feed): 피드 크기 계산 계약을 추가한다

app/src/main/java/kr/co/vividnext/sodalive/v2/widget/feed/FeedContentImageSize.kt

@@ -0,0 +1,14 @@
+package kr.co.vividnext.sodalive.v2.widget.feed
+
+data class FeedContentImageSize(
+    val widthDp: Int,
+    val heightDp: Int
+) {
+    companion object {
+        fun from(widthDp: Int, category: FeedContentCategory): FeedContentImageSize {
+            require(widthDp > 0) { "widthDp must be greater than 0." }
+            val height = (widthDp * category.ratioHeight.toFloat() / category.ratioWidth).toInt()
+            return FeedContentImageSize(widthDp = widthDp, heightDp = height)
+        }
+    }
+}

app/src/main/java/kr/co/vividnext/sodalive/v2/widget/feed/FeedSize.kt

@@ -0,0 +1,27 @@
+package kr.co.vividnext.sodalive.v2.widget.feed
+
+data class FeedSize(
+    val rootWidthDp: Int
+) {
+    companion object {
+        private const val FIGMA_ROOT_WIDTH_DP = 374
+
+        fun from(
+            variant: FeedVariant,
+            widthMode: FeedWidthMode,
+            parentAvailableWidthDp: Int,
+            horizontalItemDecorationDp: Int = 0
+        ): FeedSize {
+            val width = when (widthMode) {
+                FeedWidthMode.FigmaFixed -> FIGMA_ROOT_WIDTH_DP
+                FeedWidthMode.ParentAvailable -> {
+                    require(parentAvailableWidthDp > 0) { "parentAvailableWidthDp must be greater than 0." }
+                    require(horizontalItemDecorationDp >= 0) { "horizontalItemDecorationDp must be 0 or greater." }
+                    parentAvailableWidthDp - horizontalItemDecorationDp
+                }
+            }
+            require(width > 0) { "rootWidthDp must be greater than 0." }
+            return FeedSize(rootWidthDp = width)
+        }
+    }
+}

app/src/main/java/kr/co/vividnext/sodalive/v2/widget/feed/FeedWidthMode.kt

@@ -0,0 +1,6 @@
+package kr.co.vividnext.sodalive.v2.widget.feed
+
+enum class FeedWidthMode {
+    FigmaFixed,
+    ParentAvailable
+}

app/src/test/java/kr/co/vividnext/sodalive/v2/widget/feed/FeedContentImageSizeTest.kt

@@ -0,0 +1,40 @@
+package kr.co.vividnext.sodalive.v2.widget.feed
+
+import org.junit.Assert.assertEquals
+import kr.co.vividnext.sodalive.R
+import org.junit.Test
+
+class FeedContentImageSizeTest {
+
+    @Test
+    fun `content category keeps one to one ratio`() {
+        val size = FeedContentImageSize.from(widthDp = 163, category = FeedContentCategory.Content)
+
+        assertEquals(163, size.widthDp)
+        assertEquals(163, size.heightDp)
+        assertEquals(R.string.feed_content_category_content, FeedContentCategory.Content.labelResId)
+    }
+
+    @Test
+    fun `series category keeps configured width and uses 163 by 230 ratio`() {
+        val size = FeedContentImageSize.from(widthDp = 163, category = FeedContentCategory.Series)
+
+        assertEquals(163, size.widthDp)
+        assertEquals(230, size.heightDp)
+        assertEquals(R.string.feed_content_category_series, FeedContentCategory.Series.labelResId)
+    }
+
+    @Test
+    fun `magazine category keeps configured width and uses 163 by 218 ratio`() {
+        val size = FeedContentImageSize.from(widthDp = 163, category = FeedContentCategory.Magazine)
+
+        assertEquals(163, size.widthDp)
+        assertEquals(218, size.heightDp)
+        assertEquals(R.string.feed_content_category_magazine, FeedContentCategory.Magazine.labelResId)
+    }
+
+    @Test(expected = IllegalArgumentException::class)
+    fun `image width must be positive`() {
+        FeedContentImageSize.from(widthDp = 0, category = FeedContentCategory.Content)
+    }
+}

app/src/test/java/kr/co/vividnext/sodalive/v2/widget/feed/FeedSizeTest.kt

@@ -0,0 +1,61 @@
+package kr.co.vividnext.sodalive.v2.widget.feed
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class FeedSizeTest {
+
+    @Test
+    fun `horizontal scroll uses figma width`() {
+        val size = FeedSize.from(
+            variant = FeedVariant.Rank,
+            widthMode = FeedWidthMode.FigmaFixed,
+            parentAvailableWidthDp = 320
+        )
+
+        assertEquals(374, size.rootWidthDp)
+    }
+
+    @Test
+    fun `multi item row uses figma width`() {
+        val size = FeedSize.from(
+            variant = FeedVariant.Content,
+            widthMode = FeedWidthMode.FigmaFixed,
+            parentAvailableWidthDp = 720
+        )
+
+        assertEquals(374, size.rootWidthDp)
+    }
+
+    @Test
+    fun `single item row uses parent available width`() {
+        val size = FeedSize.from(
+            variant = FeedVariant.Live,
+            widthMode = FeedWidthMode.ParentAvailable,
+            parentAvailableWidthDp = 328
+        )
+
+        assertEquals(328, size.rootWidthDp)
+    }
+
+    @Test
+    fun `single item row subtracts horizontal item decoration from parent available width`() {
+        val size = FeedSize.from(
+            variant = FeedVariant.Live,
+            widthMode = FeedWidthMode.ParentAvailable,
+            parentAvailableWidthDp = 328,
+            horizontalItemDecorationDp = 24
+        )
+
+        assertEquals(304, size.rootWidthDp)
+    }
+
+    @Test(expected = IllegalArgumentException::class)
+    fun `parent available width must be positive for parent available mode`() {
+        FeedSize.from(
+            variant = FeedVariant.Community,
+            widthMode = FeedWidthMode.ParentAvailable,
+            parentAvailableWidthDp = 0
+        )
+    }
+}