// SPDX-License-Identifier: Unlicense OR BSD-3-Clause

package cff

import (
	
	

	ps 
	ot 
	
)

// LoadGlyph parses the glyph charstring to compute segments and path bounds.
// It returns an error if the glyph is invalid or if decoding the charstring fails.
func ( *CFF) ( tables.GlyphID) ([]ot.Segment, ps.PathBounds, error) {
	if int() >= len(.Charstrings) {
		return nil, ps.PathBounds{}, errGlyph
	}

	var (
		    ps.Machine
		 type2CharstringHandler
		  byte = 0
		    error
	)
	if .fdSelect != nil {
		,  = .fdSelect.fontDictIndex()
		if  != nil {
			return nil, ps.PathBounds{}, 
		}
	}

	 := .localSubrs[]
	 = .Run(.Charstrings[], , .globalSubrs, &)
	return .cs.Segments, .cs.Bounds, 
}

// type2CharstringHandler implements operators needed to fetch Type2 charstring metrics
type type2CharstringHandler struct {
	cs ps.CharstringReader

	// found in private DICT, needed since we can't differenciate
	// no width set from 0 width
	// `width` must be initialized to default width
	nominalWidthX float64
	width         float64
}

func (type2CharstringHandler) () ps.Context { return ps.Type2Charstring }

func ( *type2CharstringHandler) ( *ps.Machine,  ps.Operator) error {
	var  error
	if !.IsEscaped {
		switch .Operator {
		case 11: // return
			return .Return() // do not clear the arg stack
		case 14: // endchar
			if .ArgStack.Top > 0 { // width is optional
				.width = .nominalWidthX + .ArgStack.Vals[0]
			}
			.cs.ClosePath()
			return ps.ErrInterrupt
		case 10: // callsubr
			return ps.LocalSubr() // do not clear the arg stack
		case 29: // callgsubr
			return ps.GlobalSubr() // do not clear the arg stack
		case 21: // rmoveto
			if .ArgStack.Top > 2 { // width is optional
				.width = .nominalWidthX + .ArgStack.Vals[0]
			}
			 = .cs.Rmoveto()
		case 22: // hmoveto
			if .ArgStack.Top > 1 { // width is optional
				.width = .nominalWidthX + .ArgStack.Vals[0]
			}
			 = .cs.Hmoveto()
		case 4: // vmoveto
			if .ArgStack.Top > 1 { // width is optional
				.width = .nominalWidthX + .ArgStack.Vals[0]
			}
			 = .cs.Vmoveto()
		case 1, 18: // hstem, hstemhm
			.cs.Hstem()
		case 3, 23: // vstem, vstemhm
			.cs.Vstem()
		case 19, 20: // hintmask, cntrmask
			// variable number of arguments, but always even
			// for xxxmask, if there are arguments on the stack, then this is an impliied stem
			if .ArgStack.Top&1 != 0 {
				.width = .nominalWidthX + .ArgStack.Vals[0]
			}
			.cs.Hintmask()
			// the stack is managed by the previous call
			return nil

		case 5: // rlineto
			.cs.Rlineto()
		case 6: // hlineto
			.cs.Hlineto()
		case 7: // vlineto
			.cs.Vlineto()
		case 8: // rrcurveto
			.cs.Rrcurveto()
		case 24: // rcurveline
			 = .cs.Rcurveline()
		case 25: // rlinecurve
			 = .cs.Rlinecurve()
		case 26: // vvcurveto
			.cs.Vvcurveto()
		case 27: // hhcurveto
			.cs.Hhcurveto()
		case 30: // vhcurveto
			.cs.Vhcurveto()
		case 31: // hvcurveto
			.cs.Hvcurveto()
		default:
			// no other operands are allowed before the ones handled above
			 = fmt.Errorf("invalid operator %s in charstring", )
		}
	} else {
		switch .Operator {
		case 34: // hflex
			 = .cs.Hflex()
		case 35: // flex
			 = .cs.Flex()
		case 36: // hflex1
			 = .cs.Hflex1()
		case 37: // flex1
			 = .cs.Flex1()
		default:
			// no other operands are allowed before the ones handled above
			 = fmt.Errorf("invalid operator %s in charstring", )
		}
	}
	.ArgStack.Clear()
	return 
}

// ---------------------------- CFF2 format ----------------------------

// LoadGlyph parses the glyph charstring to compute segments and path bounds.
// It returns an error if the glyph is invalid or if decoding the charstring fails.
//
// [coords] must either have the same length as the variations axis, or be empty,
// and be normalized
func ( *CFF2) ( tables.GlyphID,  []tables.Coord) ([]ot.Segment, ps.PathBounds, error) {
	if int() >= len(.Charstrings) {
		return nil, ps.PathBounds{}, errGlyph
	}

	var (
		    ps.Machine
		 cff2CharstringHandler
		  byte = 0
		    error
	)
	if .fdSelect != nil {
		,  = .fdSelect.fontDictIndex()
		if  != nil {
			return nil, ps.PathBounds{}, 
		}
	}

	 := .fonts[]

	.coords = 
	.vars = .VarStore
	.setVSIndex(int(.defaultVSIndex))

	 = .Run(.Charstrings[], .localSubrs, .globalSubrs, &)

	return .cs.Segments, .cs.Bounds, 
}

// cff2CharstringHandler implements operators needed to fetch CFF2 charstring metrics
type cff2CharstringHandler struct {
	cs ps.CharstringReader

	coords []tables.Coord // normalized variation coordinates
	vars   tables.ItemVarStore

	// the currently active ItemVariationData subtable (default to 0)
	scalars []float32 // computed from the currently active ItemVariationData subtable
}

func (cff2CharstringHandler) () ps.Context { return ps.Type2Charstring }

func ( *cff2CharstringHandler) ( int) error {
	// if the font has variations, always build the scalar
	// slice, even if no variations are activated by the user:
	// the blend operator needs to know how many args to skip.
	if len(.vars.ItemVariationDatas) == 0 {
		return nil
	}

	if  >= len(.vars.ItemVariationDatas) {
		return fmt.Errorf("invalid 'vsindex' %d", )
	}

	 := .vars.ItemVariationDatas[]
	 := int32(len(.RegionIndexes)) // number of regions
	.scalars = append(.scalars[:0], make([]float32, )...)
	for ,  := range .RegionIndexes {
		 := .vars.VariationRegionList.VariationRegions[]
		.scalars[] = .Evaluate(.coords)
	}
	return nil
}

func ( *cff2CharstringHandler) ( *ps.Machine) error {
	// blend requires n*(k+1) + 1 arguments
	if .ArgStack.Top < 1 {
		return errors.New("missing n argument for blend operator")
	}
	 := int32(.ArgStack.Pop())
	 := int32(len(.scalars))
	if .ArgStack.Top < *(+1) {
		return errors.New("missing arguments for blend operator")
	}

	// actually apply the deltas only if the user has activated variations
	if len(.coords) != 0 {
		 := .ArgStack.Vals[.ArgStack.Top-*(+1) : .ArgStack.Top]
		// the first n values are the 'default' arguments
		for  := int32(0);  < ; ++ {
			 := []
			 := [+* : +(+1)*] // all the regions, for one operand
			 := 0.
			for ,  := range  {
				 += float64(.scalars[]) * 
			}
			[] =  +  // update the stack with the blended value
		}
	}

	// clear the stack, keeping only n arguments
	.ArgStack.Top -=  * 

	return nil
}

func ( *cff2CharstringHandler) ( *ps.Machine,  ps.Operator) error {
	var  error
	if !.IsEscaped {
		switch .Operator {
		case 1, 18: // hstem, hstemhm
			.cs.Hstem()
		case 3, 23: // vstem, vstemhm
			.cs.Vstem()
		case 4: // vmoveto
			 = .cs.Vmoveto()
		case 5: // rlineto
			.cs.Rlineto()
		case 6: // hlineto
			.cs.Hlineto()
		case 7: // vlineto
			.cs.Vlineto()
		case 8: // rrcurveto
			.cs.Rrcurveto()
		case 10: // callsubr
			return ps.LocalSubr() // do not clear the arg stack
		case 15: // vsindex
			if .ArgStack.Top < 1 {
				return errors.New("missing argument for vsindex operator")
			}
			 = .setVSIndex(int(.ArgStack.Pop()))
		case 16: // blend
			return .blend() // do not clear the arg stack
		case 19, 20: // hintmask, cntrmask
			// variable number of arguments, but always even
			// for xxxmask, if there are arguments on the stack, then this is an impliied stem
			.cs.Hintmask()
			// the stack is managed by the previous call
			return nil
		case 21: // rmoveto
			 = .cs.Rmoveto()
		case 22: // hmoveto
			 = .cs.Hmoveto()
		case 24: // rcurveline
			 = .cs.Rcurveline()
		case 25: // rlinecurve
			 = .cs.Rlinecurve()
		case 26: // vvcurveto
			.cs.Vvcurveto()
		case 27: // hhcurveto
			.cs.Hhcurveto()
		case 29: // callgsubr
			return ps.GlobalSubr() // do not clear the arg stack
		case 30: // vhcurveto
			.cs.Vhcurveto()
		case 31: // hvcurveto
			.cs.Hvcurveto()
		default:
			// no other operands are allowed before the ones handled above
			 = fmt.Errorf("invalid operator %s in charstring", )
		}
	} else {
		switch .Operator {
		case 34: // hflex
			 = .cs.Hflex()
		case 35: // flex
			 = .cs.Flex()
		case 36: // hflex1
			 = .cs.Hflex1()
		case 37: // flex1
			 = .cs.Flex1()
		default:
			// no other operands are allowed before the ones handled above
			 = fmt.Errorf("invalid operator %s in charstring", )
		}
	}
	.ArgStack.Clear()
	return 
}