frontend

type API interface {

	// Add returns res = i1+i2+...in
	Add(i1, i2 Variable, in ...Variable) Variable

	// Sub returns res = i1 - i2 - ...in
	Sub(i1, i2 Variable, in ...Variable) Variable

	// Neg returns -i
	Neg(i1 Variable) Variable

	// Mul returns res = i1 * i2 * ... in
	Mul(i1, i2 Variable, in ...Variable) Variable

	// DivUnchecked returns i1 / i2 . if i1 == i2 == 0, returns 0
	DivUnchecked(i1, i2 Variable) Variable

	// Div returns i1 / i2
	Div(i1, i2 Variable) Variable

	// Inverse returns res = 1 / i1
	Inverse(i1 Variable) Variable

	// ToBinary unpacks a Variable in binary,
	// n is the number of bits to select (starting from lsb)
	// n default value is fr.Bits the number of bits needed to represent a field element
	//
	// The result in in little endian (first bit= lsb)
	ToBinary(i1 Variable, n ...int) []Variable

	// FromBinary packs b, seen as a fr.Element in little endian
	FromBinary(b ...Variable) Variable

	// Xor returns a ^ b
	// a and b must be 0 or 1
	Xor(a, b Variable) Variable

	// Or returns a | b
	// a and b must be 0 or 1
	Or(a, b Variable) Variable

	// Or returns a & b
	// a and b must be 0 or 1
	And(a, b Variable) Variable

	// Select if b is true, yields i1 else yields i2
	Select(b Variable, i1, i2 Variable) Variable

	// Lookup2 performs a 2-bit lookup between i1, i2, i3, i4 based on bits b0
	// and b1. Returns i0 if b0=b1=0, i1 if b0=1 and b1=0, i2 if b0=0 and b1=1
	// and i3 if b0=b1=1.
	Lookup2(b0, b1 Variable, i0, i1, i2, i3 Variable) Variable

	// IsZero returns 1 if a is zero, 0 otherwise
	IsZero(i1 Variable) Variable

	// AssertIsEqual fails if i1 != i2
	AssertIsEqual(i1, i2 Variable)

	// AssertIsDifferent fails if i1 == i2
	AssertIsDifferent(i1, i2 Variable)

	// AssertIsBoolean fails if v != 0 || v != 1
	AssertIsBoolean(i1 Variable)

	// AssertIsLessOrEqual fails if  v > bound
	AssertIsLessOrEqual(v Variable, bound Variable)

	// Println behaves like fmt.Println but accepts cd.Variable as parameter
	// whose value will be resolved at runtime when computed by the solver
	Println(a ...Variable)

	// NewHint initializes internal variables whose value will be evaluated
	// using the provided hint function at run time from the inputs. Inputs must
	// be either variables or convertible to *big.Int. The function returns an
	// error if the number of inputs is not compatible with f.
	//
	// The hint function is provided at the proof creation time and is not
	// embedded into the circuit. From the backend point of view, the variable
	// returned by the hint function is equivalent to the user-supplied witness,
	// but its actual value is assigned by the solver, not the caller.
	//
	// No new constraints are added to the newly created wire and must be added
	// manually in the circuit. Failing to do so leads to solver failure.
	NewHint(f hint.Function, inputs ...Variable) ([]Variable, error)

	// Tag creates a tag at a given place in a circuit. The state of the tag may contain informations needed to
	// measure constraints, variables and coefficients creations through AddCounter
	Tag(name string) Tag

	// AddCounter measures the number of constraints, variables and coefficients created between two tags
	// note that the PlonK statistics are contextual since there is a post-compile phase where linear expressions
	// are factorized. That is, measuring 2 times the "repeating" piece of circuit may give less constraints the second time
	AddCounter(from, to Tag)

	// IsConstant returns true if v is a constant known at compile time
	IsConstant(v Variable) bool

	// ConstantValue returns the big.Int value of v. It
	// panics if v.IsConstant() == false
	ConstantValue(v Variable) *big.Int

	// CurveID returns the ecc.ID injected by the compiler
	Curve() ecc.ID

	// Backend returns the backend.ID injected by the compiler
	Backend() backend.ID
}

type Builder interface {
	API
	CheckVariables() error
	NewPublicVariable(name string) Variable
	NewSecretVariable(name string) Variable
	Compile() (CompiledConstraintSystem, error)
}

type Circuit interface {
	// Define declares the circuit's Constraints
	Define(api API) error
}

type CompileOption struct {
	// contains filtered or unexported fields
}

type CompiledConstraintSystem interface {
	io.WriterTo
	io.ReaderFrom

	// GetNbVariables return number of internal, secret and public Variables
	GetNbVariables() (internal, secret, public int)
	GetNbConstraints() int
	GetNbCoefficients() int

	CurveID() ecc.ID
	FrSize() int

	// ToHTML generates a human readable representation of the constraint system
	ToHTML(w io.Writer) error

	// GetCounters return the collected constraint counters, if any
	GetCounters() []compiled.Counter
}

type Counter struct {
	From, To      Tag
	NbVariables   int
	NbConstraints int
}

type NewBuilder func(ecc.ID) (Builder, error)

type Tag struct {
	Name     string
	VID, CID int
}

type Variable interface{}