#lang fontkit/racket
(require restructure)
(provide (all-defined-out))

(define LookupRecord (+Struct
                      (dictify
                       'sequenceIndex uint16be
                       'lookupListIndex uint16be)))

(define Context
  (+VersionedStruct
   uint16be
   (dictify
    ;; Simple context
    1 (dictify
       'coverage uint16be ; pointer
       'ruleSetCount uint16be
       'ruleSets (+Array uint16be 'ruleSetCount)) ; pointer

    ;; Class-based context
    2 (dictify
       'coverage uint16be ; pointer
       'classDef uint16be ; pointer
       'classSetCnt uint16be
       'classSet (+Array uint16be 'classSetCnt)) ; pointer

    3 (dictify
       'glyphCount uint16be
       'lookupCount uint16be
       'coverages (+Array uint16be 'glyphCount) ; pointer
       'lookupRecords (+Array LookupRecord 'lookupCount)))))


(define ChainingContext
  (+VersionedStruct
   uint16be
   (dictify
    ;; Simple context glyph substitution
    1 (dictify
       'coverage uint16be ; pointer
       'chainCount uint16be
       'chainRuelSets (+Array uint16be 'chainCount)) ; pointer

    ;; Class-based chaining context
    2 (dictify
       'coverage uint16be ; pointer
       'backtrackClassDef uint16be ; pointer
       'inputClassDef uint16be ; pointer
       'lookaheadClassDef uint16be ; pointer
       'chainCount uint16be
       'chainClassSet (+Array uint16be 'chainCount)) ; pointer

    ;; Coverage-based chaining context
    3 (dictify
       'backtrackGlyphCount uint16be
       'backtrackCoverage (+Array uint16be 'backtrackGlyphCount) ; pointer 
       'inputGlyphCount uint16be
       'inputCoverage (+Array uint16be 'inputGlyphCount) ; pointer
       'lookaheadGlyphCount uint16be
       'lookaheadCoverage (+Array uint16be 'lookaheadGlyphCount) ; pointer
       'lookupCount uint16be
       'lookupRecords (+Array LookupRecord 'lookupCount)))))