package iskra

// NodeKind classifies code constructs as a bitfield.
type NodeKind uint16

const (
	KindUnknown  NodeKind = 0
	KindPkg      NodeKind = 1 << 0
	KindImport   NodeKind = 1 << 1
	KindConst    NodeKind = 1 << 2
	KindVar      NodeKind = 1 << 3
	KindType     NodeKind = 1 << 4
	KindFunc     NodeKind = 1 << 5
	KindMethod   NodeKind = 1 << 6
	KindField    NodeKind = 1 << 7
	KindStmt     NodeKind = 1 << 8
	KindExpr     NodeKind = 1 << 9
	KindControl  NodeKind = 1 << 10
	KindLiteral  NodeKind = 1 << 11
)

func (k NodeKind) Has(tag NodeKind) bool { return k&tag != 0 }
func (k NodeKind) IsKnown() bool         { return k != KindUnknown }

// MetaEntry is per-record semantic metadata, indexed by record index in Tree.RecMeta.
// AdjCount/AdjOffset removed: cross-stage adjacency is key-implicit (same hash,
// different stage prefix); cross-branch adjacency is in Record.Link[2].
//
// Extra layout:
//   [0:4]   TritPath (uint32)
//   [4]     low nibble: Rotation
//   [5:8]   signature hash (24-bit, fast rejection)
//   [8:12]  ContentOffset into Tree.TokenPool
//   [12:16] ContentLen (token count)
type MetaEntry struct {
	Count    uint32
	Kind     NodeKind
	StageTag uint8
	_pad     [9]byte
	Extra    [16]byte
}

func (m *MetaEntry) ContentOffset() uint32 {
	return uint32(m.Extra[8]) |
		uint32(m.Extra[9])<<8 |
		uint32(m.Extra[10])<<16 |
		uint32(m.Extra[11])<<24
}

func (m *MetaEntry) ContentLen() uint32 {
	return uint32(m.Extra[12]) |
		uint32(m.Extra[13])<<8 |
		uint32(m.Extra[14])<<16 |
		uint32(m.Extra[15])<<24
}

func (m *MetaEntry) SetContentRef(offset, length uint32) {
	m.Extra[8] = byte(offset)
	m.Extra[9] = byte(offset >> 8)
	m.Extra[10] = byte(offset >> 16)
	m.Extra[11] = byte(offset >> 24)
	m.Extra[12] = byte(length)
	m.Extra[13] = byte(length >> 8)
	m.Extra[14] = byte(length >> 16)
	m.Extra[15] = byte(length >> 24)
}

func (m *MetaEntry) SigHash() uint32 {
	return uint32(m.Extra[5]) |
		uint32(m.Extra[6])<<8 |
		uint32(m.Extra[7])<<16
}

func (m *MetaEntry) SetSigHash(h uint32) {
	m.Extra[5] = byte(h)
	m.Extra[6] = byte(h >> 8)
	m.Extra[7] = byte(h >> 16)
}