Introduce PageStore (used by ImageRepository)

app/src/main/java/org/fairscan/app/data/ImageRepository.kt

@@ -32,6 +32,12 @@ const val SOURCE_DIR_NAME = "sources"
 const val SCAN_DIR_NAME = "scanned_pages"
 const val THUMBNAIL_DIR_NAME = "thumbnails"
 
+/**
+ * Repository responsible for:
+ * - page persistence (document.json)
+ * - image files (work, source, thumbnails)
+ * - page-level operations (add, rotate, move, delete)
+ */
 class ImageRepository(
     scanRootDir: File,
     val transformations: ImageTransformations,
@@ -52,16 +58,13 @@ class ImageRepository(
 
     private val metadataFile = File(scanDir, "document.json")
 
-    private val pagesById = mutableMapOf<String, PageV2>()
-    private var pages: MutableList<PageV2> = loadPages().also {
-        pagesById.putAll(it.associateBy { p -> p.id })
-    }
-
     private val json = Json {
         prettyPrint = false
         encodeDefaults = true
     }
 
+    private var pages: PageStore = PageStore(loadPages())
+
     private fun loadPages(): MutableList<PageV2> {
         normalizeLegacyFiles()
         val filesOnDisk = scanDir.listFiles()
@@ -87,9 +90,6 @@ class ImageRepository(
         }
     }
 
-    private fun indexOfPage(id: String): Int =
-        pages.indexOfFirst { it.id == id }
-
     private fun loadMetadata(): List<PageV2> {
         val json = metadataFile.readText()
 
@@ -121,16 +121,16 @@ class ImageRepository(
     }
 
     private fun saveMetadata() {
-        val metadata = DocumentMetadataV2(pages = pages)
+        val metadata = DocumentMetadataV2(pages = pages.pages())
         metadataFile.writeText(json.encodeToString(metadata))
     }
 
     fun pages(): List<ScanPage> =
-        pages.map {
+        pages.pages().map {
             ScanPage(it.id, it.toMetadata())
         }
 
-    private fun page(id: String): PageV2? = pagesById[id]
+    private fun page(id: String): PageV2? = pages.get(id)
 
     fun add(pageBytes: ByteArray, sourceBytes: ByteArray, metadata: PageMetadata) {
         val id = "${System.currentTimeMillis()}"
@@ -139,15 +139,15 @@ class ImageRepository(
         file.writeBytes(pageBytes)
         writeThumbnail(file)
         File(sourceDir, fileName).writeBytes(sourceBytes)
-        val page = PageV2(
+        pages.addOrReplace(
+            PageV2(
                 id = id,
                 quad = metadata.normalizedQuad.toSerializable(),
                 baseRotationDegrees = metadata.baseRotation.degrees,
                 manualRotationDegrees = metadata.manualRotation.degrees,
                 isColored = metadata.isColored
             )
-        pagesById[page.id] = page
-        pages.add(page)
+        )
         saveMetadata()
     }
 
@@ -166,31 +166,27 @@ class ImageRepository(
     fun PageV2.workFileName() = workFileName(id, manualRotationDegrees)
 
     fun rotate(id: String, clockwise: Boolean) {
-        val index = indexOfPage(id)
-        if (index < 0)
-            return
-        val page = pages[index]
+        val page = pages.get(id) ?: return
 
         val delta = if (clockwise) Rotation.R90 else Rotation.R270
-        val currentManualRotation = Rotation.fromDegrees(page.manualRotationDegrees)
-        val newManualRotation = currentManualRotation.add(delta)
-        if (newManualRotation == currentManualRotation) {
-            return // no-op
-        }
+        val newRotation = Rotation.fromDegrees(page.manualRotationDegrees).add(delta)
 
         val inputFile = File(scanDir, "$id.jpg")
-        if (!inputFile.exists()) {
-            return
-        }
-        val outputFile = File(scanDir, workFileName(id, newManualRotation.degrees))
-        if (!outputFile.exists()) {
-            val jpegQuality = ExportQuality.BALANCED.jpegQuality
-            transformations.rotate(inputFile, outputFile, newManualRotation.degrees, jpegQuality)
+        val outputFile = File(scanDir, workFileName(id, newRotation.degrees))
+
+        if (inputFile.exists() && !outputFile.exists()) {
+            transformations.rotate(
+                inputFile,
+                outputFile,
+                newRotation.degrees,
+                ExportQuality.BALANCED.jpegQuality
+            )
+        }
+
+        pages.update(id) {
+            it.copy(manualRotationDegrees = newRotation.degrees)
         }
 
-        val updated = page.copy(manualRotationDegrees = newManualRotation.degrees)
-        pagesById[id] = updated
-        pages[index] = updated
         saveMetadata()
     }
 
@@ -238,22 +234,13 @@ class ImageRepository(
     }
 
     fun movePage(id: String, newIndex: Int) {
-        val index = indexOfPage(id)
-        if (index < 0) return
-
-        val page = pages.removeAt(index)
-        val safeIndex = newIndex.coerceIn(0, pages.size)
-        pages.add(safeIndex, page)
+        pages.move(id, newIndex)
         saveMetadata()
     }
 
     fun delete(id: String) {
-        val index = indexOfPage(id)
-        if (index < 0)
-            return
-        pages.removeAt(index)
+        pages.delete(id)
         saveMetadata()
-        pagesById.remove(id)
 
         getSourceFile(id).delete()
         scanDir.listFiles()
@@ -267,7 +254,6 @@ class ImageRepository(
     fun clear() {
         pages.clear()
         saveMetadata() // "empty" json file
-        pagesById.clear()
 
         thumbnailDir.listFiles()?.forEach {
             file -> file.delete()

app/src/main/java/org/fairscan/app/data/PageStore.kt

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2025 Pierre-Yves Nicolas
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option)
+ * any later version.
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+package org.fairscan.app.data
+
+class PageStore(pages: List<PageV2>) {
+
+    private val pages = LinkedHashMap<String, PageV2>()
+        .also { map -> pages.forEach { map.put(it.id, it) } }
+
+    fun pages(): List<PageV2> =
+        pages.values.toList()
+
+    fun get(id: String): PageV2? =
+        pages[id]
+
+    fun addOrReplace(page: PageV2) =
+        pages.put(page.id, page)
+
+    fun update(id: String, transform: (PageV2) -> PageV2) {
+        val page = pages[id] ?: return
+        pages[id] = transform(page)
+    }
+
+    fun delete(id: String) = pages.remove(id)
+
+    fun clear() = pages.clear()
+
+    fun move(id: String, newIndex: Int) {
+        val page = pages[id] ?: return
+
+        val entries = pages.entries.toList()
+            .filterNot { it.key == id }
+
+        pages.clear()
+
+        val safeIndex = newIndex.coerceIn(0, entries.size)
+        entries.take(safeIndex).forEach { pages[it.key] = it.value }
+        pages.put(id, page)
+        entries.drop(safeIndex).forEach { pages[it.key] = it.value }
+    }
+}

app/src/test/java/org/fairscan/app/data/ImageRepositoryTest.kt

@@ -111,6 +111,15 @@ class ImageRepositoryTest {
         assertThat(repo().imageIds()).containsExactly("1")
     }
 
+    @Test
+    fun `no json and two files with same id`() {
+        scanDir().mkdirs()
+        File(scanDir(), "1768153479486.jpg").writeBytes(byteArrayOf(101, 102, 103))
+        File(scanDir(), "1768153479486-270.jpg").writeBytes(byteArrayOf(105, 106, 107))
+        val repo = repo()
+        assertThat(repo.imageIds()).containsExactly("1768153479486")
+    }
+
     @Test
     fun `should find existing files at initialization with no json and with rotation`() {
         scanDir().mkdirs()