grokify/mogo

package phonenumber

import (
    "math/rand"

    "github.com/grokify/mogo/crypto/randutil"
)

const (
    fakeLineNumberMin = uint16(100)
    fakeLineNumberMax = uint16(199)
)

type FakeNumberGenerator struct {
    AreaCodes []uint16
    rand      *rand.Rand
}

func NewFakeNumberGenerator(areacodes []uint16) FakeNumberGenerator {
    return FakeNumberGenerator{
        AreaCodes: areacodes,
        rand:      rand.New(randutil.NewCryptoRandSource())} // #nosec G404 - `NewCryptoRandSource()` uses `crypto/rand`.
}

// RandomAreaCode generates a random area code.
func (fng *FakeNumberGenerator) RandomAreaCode() uint16 {
    return fng.AreaCodes[fng.rand.Intn(len(fng.AreaCodes))]
}

// RandomLineNumber generates a random line number
func (fng *FakeNumberGenerator) RandomLineNumber() uint16 {
    return fng.RandomLineNumberMinMax(fakeLineNumberMin, fakeLineNumberMax)
}

// RandomLineNumber generates a random line number
func (fng *FakeNumberGenerator) RandomLineNumberMinMax(min, max uint16) uint16 {
    return uint16(fng.rand.Intn(int(max)-int(min))) + min
}

// RandomLocalNumberUS returns a US E.164 number
// AreaCode + Prefix + Line Number
func (fng *FakeNumberGenerator) RandomLocalNumberUS() uint64 {
    return fng.LocalNumberUS(fng.RandomAreaCode(), fng.RandomLineNumber())
}

// RandomLocalNumberUS returns a US E.164 number
// AreaCode + Prefix + Line Number
func (fng *FakeNumberGenerator) RandomLocalNumberUSAreaCodes(acs []uint16) uint64 {
    ac := acs[fng.rand.Intn(len(acs))]
    return fng.LocalNumberUS(ac, fng.RandomLineNumber())
}

// LocalNumberUS returns a US E.164 number given an areacode and line number
func (fng *FakeNumberGenerator) LocalNumberUS(ac uint16, ln uint16) uint64 {
    return 10000000000 + (uint64(ac) * 10000000) + (5550000) + uint64(ln)
}

// RandomLocalNumberUSUnique returns a US E.164 number
// AreaCode + Prefix + Line Number
func (fng *FakeNumberGenerator) RandomLocalNumberUSUnique(set map[uint64]int8) (uint64, map[uint64]int8) {
    try := fng.RandomLocalNumberUS()
    _, ok := set[try]
    for ok {
        try := fng.RandomLocalNumberUS()
        _, ok = set[try]
    }
    set[try] = 1
    return try, set
}

// RandomLocalNumberUSUnique returns a US E.164 number
// AreaCode + Prefix + Line Number
func (fng *FakeNumberGenerator) RandomLocalNumberUSUniqueAreaCodeSet(set map[uint64]int8, acs []uint16) (uint64, map[uint64]int8) {
    try := fng.RandomLocalNumberUSAreaCodes(acs)
    _, ok := set[try]
    for ok {
        try := fng.RandomLocalNumberUSAreaCodes(acs)
        _, ok = set[try]
    }
    set[try] = 1
    return try, set
}

// LocalNumberUS returns a US E.164 number given an areacode and line number
func LocalNumberUS(ac uint16, ln uint16) uint64 {
    return 10000000000 + (uint64(ac) * 10000000) + (5550000) + uint64(ln)
}

type AreaCodeIncrementor struct {
    Counter map[uint16]uint16
    Base    uint16
}

func NewAreaCodeIncrementor(base uint16) AreaCodeIncrementor {
    return AreaCodeIncrementor{Counter: map[uint16]uint16{}, Base: base}
}

func (aci *AreaCodeIncrementor) GetNext(ac uint16) uint64 {
    if count, ok := aci.Counter[ac]; ok {
        count++
        aci.Counter[ac] = count
        return LocalNumberUS(ac, count)
    }
    count := aci.Base + 1
    aci.Counter[ac] = count
    return LocalNumberUS(ac, count)
}