# TODOs and "Do Later" Items in Refactor Plan

Found **2 technical debt items** that need refinement after initial implementation, plus **5 future enhancements** listed at the end.

---

## Technical Debt (Must Fix Later)

### 1. Page Content Extraction (CRITICAL)

**File:** `web/src/reader/formats/reflowable/page-calculator.ts`
**Function:** `getPageContent()` (lines 373-383)
**Issue:** Currently returns entire spine content instead of extracting the actual page slice

```typescript
// Line 373-383 (CURRENT IMPLEMENTATION)
export function getPageContent(pagination: PaginationData, pageIndex: number): string {
  const page = pagination.pageMap.get(pageIndex);
  if (!page) return "";

  const spine = pagination.spineMap.get(page.charStart);
  if (!spine) return "";

  // Extract content between charStart and charEnd
  // For now, return full spine content (we'll refine this)
  return spine.content;  // ⚠️ TECHNICAL DEBT
}
```

**What needs to happen:**
```typescript
// TODO: Implement actual HTML slicing
export function getPageContent(pagination: PaginationData, pageIndex: number): string {
  const page = pagination.pageMap.get(pageIndex);
  if (!page) return "";

  const spine = pagination.spineMap.get(page.charStart);
  if (!spine) return "";

  // Extract HTML content between page.charStart and page.charEnd
  // Need to handle:
  // 1. Finding the HTML tag boundaries (don't cut in middle of <tag>)
  // 2. Balancing HTML tags
  // 3. Preserving inline styles/attributes
  // 4. Handling nested elements properly

  // Options:
  // a) Use DOMParser to parse, extract slice, re-serialize
  // b) Use HTML tag balancing algorithm
  // c) Pre-split spine into page-sized chunks during calculation

  return extractHTMLSlice(spine.content, page.charStart, page.charEnd);
}
```

**Why this is deferred:**
- HTML slicing is complex and error-prone
- Requires careful tag balancing to avoid broken HTML
- Initial implementation can work with full spine content (pages just show more content)
- Better to test pagination logic first before adding HTML slicing complexity

**Impact if not fixed:**
- Each "page" will actually show the entire spine item (could be multiple pages worth)
- Page navigation will jump by spine items, not by actual pages
- Progress tracking will be inaccurate
- User won't get true "Kindle-like" discrete pages

---

### 2. Page Content Rendering (CRITICAL)

**File:** `web/src/reader/formats/reflowable/content-renderer.ts`
**Function:** `renderPage()` (lines 637-676)
**Issue:** Currently renders full spine content instead of page slice

```typescript
// Line 653-676 (CURRENT IMPLEMENTATION)
export function renderPage(
  container: HTMLElement,
  content: string,
  pageData: PageBoundary | null
): void {
  container.innerHTML = "";

  const wrapper = document.createElement("div");
  wrapper.className = "reflowable-page";
  wrapper.style.height = "calc(100vh - 120px)";
  wrapper.style.overflow = "hidden";
  wrapper.style.position = "relative";

  // If we have page boundary data, extract that slice
  // For now, render full content (we'll refine this)
  const contentDiv = document.createElement("div");
  contentDiv.className = "page-content";
  contentDiv.innerHTML = content;  // ⚠️ TECHNICAL DEBT - should slice content
  contentDiv.style.height = "100%";
  contentDiv.style.overflow = "hidden";

  wrapper.appendChild(contentDiv);
  container.appendChild(wrapper);
}
```

**What needs to happen:**
```typescript
export function renderPage(
  container: HTMLElement,
  content: string,
  pageData: PageBoundary | null
): void {
  container.innerHTML = "";

  const wrapper = document.createElement("div");
  wrapper.className = "reflowable-page";
  wrapper.style.height = "calc(100vh - 120px)";
  wrapper.style.overflow = "hidden";
  wrapper.style.position = "relative";

  const contentDiv = document.createElement("div");
  contentDiv.className = "page-content";

  // TODO: Extract page slice using pageData.charStart and pageData.charEnd
  if (pageData) {
    const pageSlice = extractHTMLRange(content, pageData.charStart, pageData.charEnd);
    contentDiv.innerHTML = pageSlice;
  } else {
    contentDiv.innerHTML = content;
  }

  contentDiv.style.height = "100%";
  contentDiv.style.overflow = "hidden";

  wrapper.appendChild(contentDiv);
  container.appendChild(wrapper);
}
```

**Why this is deferred:**
- Depends on fixing issue #1 (page content extraction)
- Can't render page slices until we can extract them
- Initial implementation will work but show entire spines

---

### 3. Simplified CFI Generation (MEDIUM PRIORITY)

**File:** `web/src/reader/formats/reflowable/page-calculator.ts`
**Function:** `generateCFI()` (lines 241-248)

```typescript
// Line 241-248 (CURRENT IMPLEMENTATION)
// Generate CFI for a character position (simplified)
function generateCFI(spineIndex: number, charOffset: number, totalChars: number): string {
  // Simplified CFI: epubcfi(/6/4[chap1]!/4/2/1:0)
  // For now, use a simple format we can store and restore
  return `epubcfi(/6/${spineIndex}!/4/2/1:${charOffset})`;
}
```

**What needs to happen:**
- Implement proper EPUB CFI syntax
- Support ID references in spine items
- Support child element paths (not just character offsets)
- Follow [EPUB CFI specification](https://www.w3.org/TR/epub-cfi/)

**Why simplified version works for now:**
- Custom CFI format can still store/restore positions
- Database stores as string anyway
- Can migrate to proper CFI later without breaking existing data
- Most users won't notice the difference

**Impact if not fixed:**
- Progress sync with other EPUB readers won't work
- Can't jump to positions from other apps
- Not standards-compliant

---

## Future Enhancements (Optional)

These are listed in the "Next Steps After Implementation" section:

### 1. Refine getPageContent ✅ (Already listed above as #1)

### 2. Add Chapter Boundary Detection

**Description:** Ensure new chapters always start on a new page (like a physical book)

**Implementation:**
```typescript
function adjustPageBoundariesForChapters(
  pagination: PaginationData,
  toc: TOCItem[]
): PaginationData {
  // For each TOC entry, ensure it starts at page boundary
  // May need to shift pages or add blank pages
}
```

**Why optional:**
- Nice-to-have feature
- Doesn't break functionality if absent
- Requires TOC parsing integration

---

### 3. Add Reading Time Estimates

**Description:** Show "5 min read" based on word count and reading speed

**From Kavita's implementation:**
```typescript
const WORDS_PER_MINUTE_SLOW = 5000;   // 83 words per minute
const WORDS_PER_MINUTE_AVG = 15000;   // 250 words per minute
const WORDS_PER_MINUTE_FAST = 30000;  // 500 words per minute

function estimateReadingTime(wordCount: number): {
  minutes: number;
  range: string;
} {
  // Return "5-10 min" format
}
```

**Why optional:**
- UX enhancement only
- Simple addition, doesn't affect core functionality

---

### 4. Implement Search Within Book

**Description:** Full-text search across all pages

**Implementation:**
- Build search index during pagination
- Map search results to page numbers
- Highlight search terms in content

**Why optional:**
- Complex feature
- Requires additional UI components
- Can be added incrementally

---

### 5. Add Highlight/Annotation Support

**Description:** Allow users to highlight text and add notes

**Implementation:**
- Store annotations in database with CFI positions
- Render highlights in content
- CRUD operations for annotations

**Why optional:**
- Separate feature from pagination
- Requires backend API work
- Can be implemented independently

---

## Summary

### Critical (Must Fix Before Production)
1. ✅ **Page content extraction** - Core functionality broken without this
2. ✅ **Page rendering** - Depends on #1
3. ⚠️ **CFI generation** - Works for now, but should be standards-compliant

### Optional (Can Ship Without)
1. Chapter boundary detection
2. Reading time estimates
3. Search within book
4. Highlights/annotations

---

## Recommended Implementation Order

**Phase 1 (Current):** Get basic pagination working
- Use full spine content for now
- Test navigation, progress tracking, page calculation

**Phase 2 (Next Sprint):** Fix page content extraction
- Implement HTML slicing algorithm
- Fix `getPageContent()` and `renderPage()`
- Test with actual multi-page spines

**Phase 3 (Later):** Standards compliance
- Implement proper EPUB CFI
- Add chapter boundary detection
- Improve CFI parsing/validation

**Phase 4 (Future):** UX enhancements
- Reading time estimates
- Search
- Highlights/annotations

---

## Workarounds for Phase 1

While page content extraction is not implemented:

1. **Accept showing full spine content** - Users can still navigate between spines
2. **Smaller spines** - Some EPUBs split content into small files anyway
3. **Pre-split during parsing** - Could split spines into smaller chunks during initial parse (temporary workaround)
4. **CSS overflow: hidden** - At least hides overflow visually, even if content is there

The critical items should be prioritized immediately after basic pagination is tested and working.