/- Copyright (c) 2026 Sovereign Research Stack. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Research Stack Team

SwarmENEMiddleware.lean — Swarm ENE Middleware Routing Rules

Replaces infra/swarm_ene_middleware.py routing logic with a formal Lean module.
Defines swarm API-ENE middleware routing rules and semantic similarity.

Per AGENTS.md:
  - Q16_16 for scoring (§1.4)
  - PascalCase types, camelCase functions (§2)
  - Theorems for correctness (§4)
  - No proof placeholders in committed code (§1.6)
-/

import Mathlib.Data.Nat.Basic
import Mathlib.Data.List.Basic
import Std

namespace Semantics.SwarmENEMiddleware

-- ═══════════════════════════════════════════════════════════════════════════
-- §0  Q16_16 Fixed-Point Arithmetic
-- ═══════════════════════════════════════════════════════════════════════════

structure Q16_16 where
  raw : Int
  deriving Repr, DecidableEq, Inhabited

namespace Q16_16
  def zero : Q16_16 := ⟨0⟩
  def one : Q16_16 := ⟨65536⟩
  def ofFrac (num denom : Nat) : Q16_16 :=
    if denom = 0 then zero else ⟨(num * 65536) / denom⟩
end Q16_16

-- ═══════════════════════════════════════════════════════════════════════════
-- §1  Query Cache Structure
-- ═══════════════════════════════════════════════════════════════════════════

structure SwarmQueryCache where
  queryHash : String
  subjects : List String
  keywords : Option String
  formalStatus : Option String
  count : Nat
  confidence : Q16_16
  timestamp : Nat
  semanticVector : List Q16_16
  ttl : Nat
  hitCount : Nat
  deriving Repr, Inhabited

-- ═══════════════════════════════════════════════════════════════════════════
-- §2  Semantic Vector Operations
-- ═══════════════════════════════════════════════════════════════════════════

/-- Compute cosine similarity between two Q16_16 vectors -/
def cosineSimilarity (v1 v2 : List Q16_16) : Q16_16 :=
  if v1.isEmpty ∨ v2.isEmpty then
    Q16_16.zero
  else
    let zipped := List.zip v1 v2
    let dotProduct := List.foldl (fun acc (pair : Q16_16 × Q16_16) => 
      let a := pair.1
      let b := pair.2
      let product := (a.raw.toNat * b.raw.toNat) / 65536
      { raw := acc.raw + product }
    ) Q16_16.zero zipped
    let norm1 := List.foldl (fun acc (a : Q16_16) => 
      let product := (a.raw.toNat * a.raw.toNat) / 65536
      { raw := acc.raw + product }
    ) Q16_16.zero v1
    let norm2 := List.foldl (fun acc (a : Q16_16) => 
      let product := (a.raw.toNat * a.raw.toNat) / 65536
      { raw := acc.raw + product }
    ) Q16_16.zero v2
    if norm1.raw = 0 ∨ norm2.raw = 0 then
      Q16_16.zero
    else
      let product := norm1.raw.toNat * norm2.raw.toNat
      if product = 0 then Q16_16.zero
      else Q16_16.ofFrac dotProduct.raw.toNat product

/-- Check if cache entry is still valid based on TTL -/
def isCacheValid (cacheEntry : SwarmQueryCache) (currentTime : Nat) : Bool :=
  currentTime - cacheEntry.timestamp < cacheEntry.ttl

/-- Increment hit count for cache entry -/
def incrementHitCount (cacheEntry : SwarmQueryCache) : SwarmQueryCache :=
  { cacheEntry with hitCount := cacheEntry.hitCount + 1 }

-- ═══════════════════════════════════════════════════════════════════════════
-- §3  Routing Rules
-- ═══════════════════════════════════════════════════════════════════════════

structure RoutingDecision where
  useCache : Bool
  cacheHit : Bool
  shouldInvalidate : Bool
  similarityThreshold : Q16_16
  deriving Repr, Inhabited

/-- Make routing decision for query -/
def makeRoutingDecision (hasCacheEntry : Bool) (cacheEntry : Option SwarmQueryCache) 
    (currentTime : Nat) (queryVector cachedVector : List Q16_16) : RoutingDecision :=
  let useCache :=
    match cacheEntry with
    | some entry => isCacheValid entry currentTime
    | none => false
  let cacheHit := hasCacheEntry && useCache
  let similarity := 
    if queryVector.isEmpty ∨ cachedVector.isEmpty then Q16_16.zero
    else cosineSimilarity queryVector cachedVector
  let shouldInvalidate := hasCacheEntry && (not useCache)
  
  {
    useCache := useCache,
    cacheHit := cacheHit,
    shouldInvalidate := shouldInvalidate,
    similarityThreshold := similarity
  }

-- ═══════════════════════════════════════════════════════════════════════════
-- §4  Theorems
-- ═══════════════════════════════════════════════════════════════════════════

/-- Cache hit count always increases after increment -/
theorem hitCountIncreases (cacheEntry : SwarmQueryCache) :
    (incrementHitCount cacheEntry).hitCount = cacheEntry.hitCount + 1 := by
  simp [incrementHitCount]

-- ═══════════════════════════════════════════════════════════════════════════
-- §5  Example Usage
-- ═══════════════════════════════════════════════════════════════════════════

#eval let v1 := [Q16_16.ofFrac 1 2, Q16_16.ofFrac 1 2, Q16_16.ofFrac 1 2]
      let v2 := [Q16_16.ofFrac 1 2, Q16_16.ofFrac 1 2, Q16_16.ofFrac 1 2]
      cosineSimilarity v1 v2

#eval let cacheEntry := {
        queryHash := "test",
        subjects := ["geometry"],
        keywords := none,
        formalStatus := none,
        count := 5,
        confidence := Q16_16.ofFrac 95 100,
        timestamp := 1000,
        semanticVector := [],
        ttl := 3600,
        hitCount := 0
      }
      isCacheValid cacheEntry 4000

#eval incrementHitCount {
        queryHash := "test",
        subjects := ["geometry"],
        keywords := none,
        formalStatus := none,
        count := 5,
        confidence := Q16_16.ofFrac 95 100,
        timestamp := 1000,
        semanticVector := [],
        ttl := 3600,
        hitCount := 5
      }

end Semantics.SwarmENEMiddleware