import Semantics.FixedPoint
import Semantics.BraidStrand
import Semantics.BraidBracket
import Semantics.MeshRouting

/-!
# BraidVCNBridge — Map braid operations to VCN frame encoding.

Bridges the braid algebra (BraidStrand, BraidBracket) to the VCN video encode
substrate for GPU-accelerated computation.
-/

namespace Semantics.BraidVCNBridge

open Semantics
open Semantics.BraidBracket
open Semantics.BraidBracket.BraidBracket
open Semantics.BraidStrand

def encodeBraidStrand (s : BraidStrand) : Array UInt8 :=
  let px := s.phaseAcc.x.val.toNat
  let py := s.phaseAcc.y.val.toNat
  let mag := s.magnitude.val.toNat
  let gap := s.bracket.gap.val.toNat
  let packQ16 (v : Nat) : Array UInt8 :=
    #[ UInt8.ofNat (v % 256),
       UInt8.ofNat ((v / 256) % 256),
       UInt8.ofNat ((v / 65536) % 256),
       UInt8.ofNat ((v / 16777216) % 256) ]
  packQ16 px ++ packQ16 py ++ packQ16 mag ++ packQ16 gap

def encodeBraidCrossing (bij bi bj : BraidBracket) : Array UInt8 :=
  let res := crossingResidual bij bi bj
  let packQ16 (v : Q16_16) : Array UInt8 :=
    let n := v.val.toNat
    #[ UInt8.ofNat (n % 256),
       UInt8.ofNat ((n / 256) % 256),
       UInt8.ofNat ((n / 65536) % 256),
       UInt8.ofNat ((n / 16777216) % 256) ]
  packQ16 res.lower ++ packQ16 res.upper ++
  packQ16 res.gap ++ packQ16 res.kappa ++ packQ16 res.phi

-- TODO(lean-port): Mountain merge encoding (needs BraidField import)
-- TODO(lean-port): PISTField frame encoding (needs BraidField import)
-- TODO(lean-port): eigensolid_convergence — crossing loop stabilizes
-- TODO(lean-port): receipt_invertible — encode + decode is bijective

end Semantics.BraidVCNBridge
