From bb151caee7cebb2c3f2ad58156e56e5286beaf8c Mon Sep 17 00:00:00 2001
From: Dave Allie <dave@daveallie.com>
Date: Sat, 6 Dec 2025 22:04:59 +1100
Subject: [PATCH] Version section bin files

---
 lib/Epub/Epub/Section.cpp        | 38 ++++++++++++++++++++------------
 lib/Epub/Epub/Section.h          |  5 +++--
 src/CrossPointState.cpp          |  6 ++---
 src/screens/EpubReaderScreen.cpp |  2 +-
 4 files changed, 31 insertions(+), 20 deletions(-)

diff --git a/lib/Epub/Epub/Section.cpp b/lib/Epub/Epub/Section.cpp
index 902127a..aa9ad95 100644
--- a/lib/Epub/Epub/Section.cpp
+++ b/lib/Epub/Epub/Section.cpp
@@ -7,6 +7,9 @@
 
 #include "EpubHtmlParserSlim.h"
 #include "Page.h"
+#include "Serialization.h"
+
+constexpr uint8_t SECTION_FILE_VERSION = 2;
 
 void Section::onPageComplete(const Page* page) {
   Serial.printf("Page %d complete - free mem: %lu\n", pageCount, ESP.getFreeHeap());
@@ -21,7 +24,14 @@ void Section::onPageComplete(const Page* page) {
   delete page;
 }
 
-bool Section::hasCache() {
+void Section::writeCacheMetadata() const {
+  std::ofstream outputFile(("/sd" + cachePath + "/section.bin").c_str());
+  serialization::writePod(outputFile, SECTION_FILE_VERSION);
+  serialization::writePod(outputFile, pageCount);
+  outputFile.close();
+}
+
+bool Section::loadCacheMetadata() {
   if (!SD.exists(cachePath.c_str())) {
     return false;
   }
@@ -31,14 +41,18 @@ bool Section::hasCache() {
     return false;
   }
 
-  File sectionFile = SD.open(sectionFilePath.c_str(), FILE_READ);
-  uint8_t pageCountBytes[2] = {0, 0};
-  sectionFile.read(pageCountBytes, 2);
-  sectionFile.close();
-
-  pageCount = pageCountBytes[0] + (pageCountBytes[1] << 8);
+  std::ifstream inputFile(("/sd" + sectionFilePath).c_str());
+  uint8_t version;
+  serialization::readPod(inputFile, version);
+  if (version != SECTION_FILE_VERSION) {
+    inputFile.close();
+    SD.remove(sectionFilePath.c_str());
+    Serial.printf("Section state file: Unknown version %u\n", version);
+    return false;
+  }
+  serialization::readPod(inputFile, pageCount);
+  inputFile.close();
   Serial.printf("Loaded cache: %d pages\n", pageCount);
-
   return true;
 }
 
@@ -86,16 +100,12 @@ bool Section::persistPageDataToSD() {
     return false;
   }
 
-  File sectionFile = SD.open((cachePath + "/section.bin").c_str(), FILE_WRITE, true);
-  const uint8_t pageCountBytes[2] = {static_cast<uint8_t>(pageCount & 0xFF),
-                                     static_cast<uint8_t>((pageCount >> 8) & 0xFF)};
-  sectionFile.write(pageCountBytes, 2);
-  sectionFile.close();
+  writeCacheMetadata();
 
   return true;
 }
 
-void Section::renderPage() {
+void Section::renderPage() const {
   if (0 <= currentPage && currentPage < pageCount) {
     const auto filePath = "/sd" + cachePath + "/page_" + std::to_string(currentPage) + ".bin";
     std::ifstream inputFile(filePath);
diff --git a/lib/Epub/Epub/Section.h b/lib/Epub/Epub/Section.h
index 4a8d2e1..86acebe 100644
--- a/lib/Epub/Epub/Section.h
+++ b/lib/Epub/Epub/Section.h
@@ -21,9 +21,10 @@ class Section {
     cachePath = epub->getCachePath() + "/" + std::to_string(spineIndex);
   }
   ~Section() = default;
-  bool hasCache();
+  void writeCacheMetadata() const;
+  bool loadCacheMetadata();
   void setupCacheDir() const;
   void clearCache() const;
   bool persistPageDataToSD();
-  void renderPage();
+  void renderPage() const;
 };
diff --git a/src/CrossPointState.cpp b/src/CrossPointState.cpp
index 7564aac..bb76603 100644
--- a/src/CrossPointState.cpp
+++ b/src/CrossPointState.cpp
@@ -6,12 +6,12 @@
 
 #include <fstream>
 
-constexpr uint8_t STATE_VERSION = 1;
+constexpr uint8_t STATE_FILE_VERSION = 1;
 constexpr char STATE_FILE[] = "/sd/.crosspoint/state.bin";
 
 bool CrossPointState::saveToFile() const {
   std::ofstream outputFile(STATE_FILE);
-  serialization::writePod(outputFile, STATE_VERSION);
+  serialization::writePod(outputFile, STATE_FILE_VERSION);
   serialization::writeString(outputFile, openEpubPath);
   outputFile.close();
   return true;
@@ -22,7 +22,7 @@ bool CrossPointState::loadFromFile() {
 
   uint8_t version;
   serialization::readPod(inputFile, version);
-  if (version != STATE_VERSION) {
+  if (version != STATE_FILE_VERSION) {
     Serial.printf("CrossPointState: Unknown version %u\n", version);
     inputFile.close();
     return false;
diff --git a/src/screens/EpubReaderScreen.cpp b/src/screens/EpubReaderScreen.cpp
index 374b468..6452df8 100644
--- a/src/screens/EpubReaderScreen.cpp
+++ b/src/screens/EpubReaderScreen.cpp
@@ -148,7 +148,7 @@ void EpubReaderScreen::renderPage() {
     const auto filepath = epub->getSpineItem(currentSpineIndex);
     Serial.printf("Loading file: %s, index: %d\n", filepath.c_str(), currentSpineIndex);
     section = new Section(epub, currentSpineIndex, renderer);
-    if (!section->hasCache()) {
+    if (!section->loadCacheMetadata()) {
       Serial.println("Cache not found, building...");
 
       {