Move to smart pointers and split out ParsedText class (#6)

* Move to smart pointers and split out ParsedText class

* Cleanup ParsedText

* Fix clearCache functions and clear section cache if page load fails

* Bump Page and Section file versions

* Combine removeDir implementations in Epub

* Adjust screen margins

lib/Epub/Epub/ParsedText.cpp

@@ -0,0 +1,167 @@
+#include "ParsedText.h"
+
+#include <GfxRenderer.h>
+
+#include <algorithm>
+#include <cmath>
+#include <limits>
+#include <vector>
+
+constexpr int MAX_COST = std::numeric_limits<int>::max();
+
+void ParsedText::addWord(std::string word, const EpdFontStyle fontStyle) {
+  if (word.empty()) return;
+
+  words.push_back(std::move(word));
+  wordStyles.push_back(fontStyle);
+}
+
+// Consumes data to minimize memory usage
+std::list<std::shared_ptr<TextBlock>> ParsedText::layoutAndExtractLines(const GfxRenderer& renderer, const int fontId,
+                                                                        const int horizontalMargin) {
+  if (words.empty()) {
+    return {};
+  }
+
+  const size_t totalWordCount = words.size();
+  const int pageWidth = renderer.getScreenWidth() - horizontalMargin;
+  const int spaceWidth = renderer.getSpaceWidth(fontId);
+
+  std::vector<uint16_t> wordWidths;
+  wordWidths.reserve(totalWordCount);
+
+  auto wordsIt = words.begin();
+  auto wordStylesIt = wordStyles.begin();
+
+  while (wordsIt != words.end()) {
+    wordWidths.push_back(renderer.getTextWidth(fontId, wordsIt->c_str(), *wordStylesIt));
+
+    std::advance(wordsIt, 1);
+    std::advance(wordStylesIt, 1);
+  }
+
+  // DP table to store the minimum badness (cost) of lines starting at index i
+  std::vector<int> dp(totalWordCount);
+  // 'ans[i]' stores the index 'j' of the *last word* in the optimal line starting at 'i'
+  std::vector<size_t> ans(totalWordCount);
+
+  // Base Case
+  dp[totalWordCount - 1] = 0;
+  ans[totalWordCount - 1] = totalWordCount - 1;
+
+  for (int i = totalWordCount - 2; i >= 0; --i) {
+    int currlen = -spaceWidth;
+    dp[i] = MAX_COST;
+
+    for (size_t j = i; j < totalWordCount; ++j) {
+      // Current line length: previous width + space + current word width
+      currlen += wordWidths[j] + spaceWidth;
+
+      if (currlen > pageWidth) {
+        break;
+      }
+
+      int cost;
+      if (j == totalWordCount - 1) {
+        cost = 0;  // Last line
+      } else {
+        const int remainingSpace = pageWidth - currlen;
+        // Use long long for the square to prevent overflow
+        const long long cost_ll = static_cast<long long>(remainingSpace) * remainingSpace + dp[j + 1];
+
+        if (cost_ll > MAX_COST) {
+          cost = MAX_COST;
+        } else {
+          cost = static_cast<int>(cost_ll);
+        }
+      }
+
+      if (cost < dp[i]) {
+        dp[i] = cost;
+        ans[i] = j;  // j is the index of the last word in this optimal line
+      }
+    }
+  }
+
+  // Stores the index of the word that starts the next line (last_word_index + 1)
+  std::vector<size_t> lineBreakIndices;
+  size_t currentWordIndex = 0;
+  constexpr size_t MAX_LINES = 1000;
+
+  while (currentWordIndex < totalWordCount) {
+    if (lineBreakIndices.size() >= MAX_LINES) {
+      break;
+    }
+
+    size_t nextBreakIndex = ans[currentWordIndex] + 1;
+    lineBreakIndices.push_back(nextBreakIndex);
+
+    currentWordIndex = nextBreakIndex;
+  }
+
+  std::list<std::shared_ptr<TextBlock>> lines;
+
+  // Initialize iterators for consumption
+  auto wordStartIt = words.begin();
+  auto wordStyleStartIt = wordStyles.begin();
+  size_t wordWidthIndex = 0;
+
+  size_t lastBreakAt = 0;
+  for (const size_t lineBreak : lineBreakIndices) {
+    const size_t lineWordCount = lineBreak - lastBreakAt;
+
+    // Calculate end iterators for the range to splice
+    auto wordEndIt = wordStartIt;
+    auto wordStyleEndIt = wordStyleStartIt;
+    std::advance(wordEndIt, lineWordCount);
+    std::advance(wordStyleEndIt, lineWordCount);
+
+    // Calculate total word width for this line
+    int lineWordWidthSum = 0;
+    for (size_t i = 0; i < lineWordCount; ++i) {
+      lineWordWidthSum += wordWidths[wordWidthIndex + i];
+    }
+
+    // Calculate spacing
+    const int spareSpace = pageWidth - lineWordWidthSum;
+    int spacing = spaceWidth;
+    const bool isLastLine = lineBreak == totalWordCount;
+
+    if (style == TextBlock::JUSTIFIED && !isLastLine && lineWordCount >= 2) {
+      spacing = spareSpace / (lineWordCount - 1);
+    }
+
+    // Calculate initial x position
+    uint16_t xpos = 0;
+    if (style == TextBlock::RIGHT_ALIGN) {
+      xpos = spareSpace - (lineWordCount - 1) * spaceWidth;
+    } else if (style == TextBlock::CENTER_ALIGN) {
+      xpos = (spareSpace - (lineWordCount - 1) * spaceWidth) / 2;
+    }
+
+    // Pre-calculate X positions for words
+    std::list<uint16_t> lineXPos;
+    for (size_t i = 0; i < lineWordCount; ++i) {
+      const uint16_t currentWordWidth = wordWidths[wordWidthIndex + i];
+      lineXPos.push_back(xpos);
+      xpos += currentWordWidth + spacing;
+    }
+
+    // *** CRITICAL STEP: CONSUME DATA USING SPLICE ***
+    std::list<std::string> lineWords;
+    lineWords.splice(lineWords.begin(), words, wordStartIt, wordEndIt);
+    std::list<EpdFontStyle> lineWordStyles;
+    lineWordStyles.splice(lineWordStyles.begin(), wordStyles, wordStyleStartIt, wordStyleEndIt);
+
+    lines.push_back(
+        std::make_shared<TextBlock>(std::move(lineWords), std::move(lineXPos), std::move(lineWordStyles), style));
+
+    // Update pointers/indices for the next line
+    wordStartIt = wordEndIt;
+    wordStyleStartIt = wordStyleEndIt;
+    wordWidthIndex += lineWordCount;
+    lastBreakAt = lineBreak;
+  }
+
+  return lines;
+}