package rings

import (
	"net/netip"

	"darvaza.org/core"
)

// DecodeAddress ... TODO
//
// revive:disable:function-result-limit
func DecodeAddress(addr netip.Addr) (RingID, RegionID, ZoneID, uint) {
	// revive:enable:function-result-limit
	if addr.IsValid() {
		if addr.Is4In6() {
			addr = addr.Unmap()
		}

		if addr.Is4() {
			a4 := addr.As4()
			return unsafeDecodeAddress(a4[0], a4[1], a4[2], a4[3])
		}
	}

	return InvalidRing, 0, 0, 0
}

// revive:disable:function-result-limit
func unsafeDecodeAddress(a, b, c, d byte) (RingID, RegionID, ZoneID, uint) {
	// revive:enable:function-result-limit
	switch {
	case a != 10:
		return InvalidRing, 0, 0, 0
	case b&0xf0 != 0:
		k := RingThree
		r := RegionID(b >> 4)

		n2 := uint(b & 0x0f)
		n1 := uint(c)
		n0 := uint(d)
		n := n0 + n1<<8 + n2<<16

		return k, r, 0, n
	case b&0x0f != 0:
		r := RegionID(b)
		z := ZoneID(c >> 4)
		k := core.IIf(z == 0, RingTwo, RingOne)

		n1 := uint(c & 0x0f)
		n0 := uint(d)
		n := n0 + n1<<8

		return k, r, z, n
	default: // b == 0
		k := RingZero
		r := RegionID(c >> 4)
		z := ZoneID(c & 0xf)
		n := uint(d)

		return k, r, z, n
	}
}