#pragma once

#include <Arduino.h>
#include <vector>

struct Token {
  uint32_t offset;
  uint16_t length;
  uint8_t trailingLineBreaks;
};
static_assert(sizeof(Token) == 8, "Token storage must remain memory-budgeted");

struct StyleToken {
  uint32_t index;
  uint8_t styleFlags;
  uint8_t timingModifier;
};

class Reader {
 public:
  bool load(const String& book, const std::vector<uint8_t>& sidecar);
  void restoreAtParagraphStart(uint32_t savedWord);
  const String currentWord() const;
  bool advance();
  bool previousParagraph();
  bool nextParagraph();
  bool lastParagraph();
  uint32_t currentIndex() const;
  uint32_t wordCount() const;
  uint8_t progressPercent() const;
  uint32_t delayMs(uint16_t wpm) const;
  uint8_t currentStyleFlags() const;
  bool sidecarValid() const;

 private:
  String book_;
  std::vector<Token> tokens_;
  std::vector<StyleToken> styleTokens_;
  std::vector<uint32_t> paragraphStarts_;
  uint32_t index_ = 0;
  size_t nextStyleToken_ = 0;
  bool sidecarValid_ = false;
  uint64_t sourceFingerprint_ = 0;

  bool loadSidecar(const std::vector<uint8_t>& sidecar);
  uint32_t paragraphStartFor(uint32_t wordIndex) const;
  void seekStyleToken();
  const StyleToken* currentStyleToken() const;
};