package types

import (
	"errors"
	"fmt"
	"math/big"
)

// Uint wraps integer with 256 bit range bound
// Checks overflow, underflow and division by zero
// Exists in range from 0 to 2^256-1
type Uint struct {
	i *big.Int
}

// NewUintFromBigUint constructs Uint from big.Uint
func NewUintFromBigInt(i *big.Int) Uint {
	u, err := checkNewUint(i)
	if err != nil {
		panic(fmt.Errorf("overflow: %s", err))
	}
	return u
}

// NewUint constructs Uint from int64
func NewUint(n uint64) Uint {
	i := new(big.Int)
	i.SetUint64(n)
	return NewUintFromBigInt(i)
}

// NewUintFromString constructs Uint from string
func NewUintFromString(s string) Uint {
	u, err := ParseUint(s)
	if err != nil {
		panic(err)
	}
	return u
}

// ZeroUint returns unsigned zero.
func ZeroUint() Uint { return Uint{big.NewInt(0)} }

// OneUint returns Uint value with one.
func OneUint() Uint { return Uint{big.NewInt(1)} }

// Uint64 converts Uint to uint64
// Panics if the value is out of range
func (u Uint) Uint64() uint64 {
	if !u.i.IsUint64() {
		panic("Uint64() out of bound")
	}
	return u.i.Uint64()
}

// IsZero returns 1 if the uint equals to 0.
func (u Uint) IsZero() bool { return u.Equal(ZeroUint()) }

// Equal compares two Uints
func (u Uint) Equal(u2 Uint) bool { return equal(u.i, u2.i) }

// GT returns true if first Uint is greater than second
func (u Uint) GT(u2 Uint) bool { return gt(u.i, u2.i) }

// GTE returns true if first Uint is greater than second
func (u Uint) GTE(u2 Uint) bool { return u.GT(u2) || u.Equal(u2) }

// LT returns true if first Uint is lesser than second
func (u Uint) LT(u2 Uint) bool { return lt(u.i, u2.i) }

// LTE returns true if first Uint is lesser than or equal to the second
func (u Uint) LTE(u2 Uint) bool { return !u.GTE(u2) }

// Add adds Uint from another
func (u Uint) Add(u2 Uint) Uint { return NewUintFromBigInt(new(big.Int).Add(u.i, u2.i)) }

// Add convert uint64 and add it to Uint
func (u Uint) AddUint64(u2 uint64) Uint { return u.Add(NewUint(u2)) }

// Sub adds Uint from another
func (u Uint) Sub(u2 Uint) Uint { return NewUintFromBigInt(new(big.Int).Sub(u.i, u2.i)) }

// SubUint64 adds Uint from another
func (u Uint) SubUint64(u2 uint64) Uint { return u.Sub(NewUint(u2)) }

// Mul multiplies two Uints
func (u Uint) Mul(u2 Uint) (res Uint) {
	return NewUintFromBigInt(new(big.Int).Mul(u.i, u2.i))
}

// Mul multiplies two Uints
func (u Uint) MulUint64(u2 uint64) (res Uint) { return u.Mul(NewUint(u2)) }

// Div divides Uint with Uint
func (u Uint) Div(u2 Uint) (res Uint) { return NewUintFromBigInt(div(u.i, u2.i)) }

// Div divides Uint with uint64
func (u Uint) DivUint64(u2 uint64) Uint { return u.Div(NewUint(u2)) }

// Return the minimum of the Uints
func MinUint(u1, u2 Uint) Uint { return NewUintFromBigInt(min(u1.i, u2.i)) }

// Return the maximum of the Uints
func MaxUint(u1, u2 Uint) Uint { return NewUintFromBigInt(max(u1.i, u2.i)) }

// Human readable string
func (u Uint) String() string { return u.i.String() }

// Testing purpose random Uint generator
func randomUint(u Uint) Uint { return NewUintFromBigInt(random(u.i)) }

// MarshalAmino defines custom encoding scheme
func (u Uint) MarshalAmino() (string, error) {
	if u.i == nil { // Necessary since default Uint initialization has i.i as nil
		u.i = new(big.Int)
	}
	return marshalAmino(u.i)
}

// UnmarshalAmino defines custom decoding scheme
func (u *Uint) UnmarshalAmino(text string) error {
	if u.i == nil { // Necessary since default Uint initialization has i.i as nil
		u.i = new(big.Int)
	}
	return unmarshalAmino(u.i, text)
}

// MarshalJSON defines custom encoding scheme
func (u Uint) MarshalJSON() ([]byte, error) {
	if u.i == nil { // Necessary since default Uint initialization has i.i as nil
		u.i = new(big.Int)
	}
	return marshalJSON(u.i)
}

// UnmarshalJSON defines custom decoding scheme
func (u *Uint) UnmarshalJSON(bz []byte) error {
	if u.i == nil { // Necessary since default Uint initialization has i.i as nil
		u.i = new(big.Int)
	}
	return unmarshalJSON(u.i, bz)
}

//__________________________________________________________________________

// UintOverflow returns true if a given unsigned integer overflows and false
// otherwise.
func UintOverflow(i *big.Int) error {
	if i.Sign() < 0 {
		return errors.New("non-positive integer")
	}
	if i.BitLen() > 256 {
		return fmt.Errorf("bit length %d greater than 256", i.BitLen())
	}
	return nil
}

// ParseUint reads a string-encoded Uint value and return a Uint.
func ParseUint(s string) (Uint, error) {
	i, ok := new(big.Int).SetString(s, 0)
	if !ok {
		return Uint{}, fmt.Errorf("cannot convert %q to big.Int", s)
	}
	return checkNewUint(i)
}

func checkNewUint(i *big.Int) (Uint, error) {
	if err := UintOverflow(i); err != nil {
		return Uint{}, err
	}
	return Uint{i}, nil
}