/- 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

GemmaIntegration.lean — Gemma 4 Integration Prompt Routing

Replaces infra/gemma_4_integration.py prompt routing logic with a formal Lean module.
Defines Gemma 4 model variants, task types, and prompt routing logic.

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.GemmaIntegration

-- ═══════════════════════════════════════════════════════════════════════════
-- §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  Gemma Variant Enumeration
-- ═══════════════════════════════════════════════════════════════════════════

inductive GemmaVariant where
  | e2B : GemmaVariant  -- 2B effective parameters, audio support
  | e4B : GemmaVariant  -- 4B effective parameters, audio support - RECOMMENDED
  | e31B : GemmaVariant  -- 31B dense model
  | e26B_A4B : GemmaVariant  -- 26B total, 4B active MoE
  deriving Repr, DecidableEq, Inhabited

/-- Get model size in billions of parameters -/
def gemmaVariantSize (variant : GemmaVariant) : Nat :=
  match variant with
  | GemmaVariant.e2B => 2
  | GemmaVariant.e4B => 4
  | GemmaVariant.e31B => 31
  | GemmaVariant.e26B_A4B => 26

/-- Check if variant supports audio -/
def supportsAudio (variant : GemmaVariant) : Bool :=
  match variant with
  | GemmaVariant.e2B => true
  | GemmaVariant.e4B => true
  | GemmaVariant.e31B => false
  | GemmaVariant.e26B_A4B => false

/-- Check if variant is MoE (Mixture of Experts) -/
def isMoEModel (variant : GemmaVariant) : Bool :=
  match variant with
  | GemmaVariant.e26B_A4B => true
  | _ => false

-- ═══════════════════════════════════════════════════════════════════════════
-- §2  Gemma Task Enumeration
-- ═══════════════════════════════════════════════════════════════════════════

inductive GemmaTask where
  | textGeneration : GemmaTask
  | multimodalProcessing : GemmaTask
  | audioTranscription : GemmaTask
  | imageUnderstanding : GemmaTask
  | reasoning : GemmaTask
  | codeGeneration : GemmaTask
  | functionCalling : GemmaTask
  deriving Repr, DecidableEq, Inhabited

/-- Check if task requires audio support -/
def requiresAudio (task : GemmaTask) : Bool :=
  match task with
  | GemmaTask.audioTranscription => true
  | _ => false

/-- Check if task requires multimodal support -/
def requiresMultimodal (task : GemmaTask) : Bool :=
  match task with
  | GemmaTask.multimodalProcessing => true
  | GemmaTask.imageUnderstanding => true
  | _ => false

-- ═══════════════════════════════════════════════════════════════════════════
-- §3  Task Request Structure
-- ═══════════════════════════════════════════════════════════════════════════

inductive TaskStatus where
  | pending : TaskStatus
  | inProgress : TaskStatus
  | completed : TaskStatus
  | failed : TaskStatus
  deriving Repr, DecidableEq, Inhabited

structure GemmaTaskRequest where
  taskId : String
  taskType : GemmaTask
  variant : GemmaVariant
  enableThinking : Bool
  maxTokens : Nat
  priority : Nat
  status : TaskStatus
  createdAt : Nat
  deriving Repr, Inhabited

-- ═══════════════════════════════════════════════════════════════════════════
-- §4  Variant-Task Compatibility
-- ═══════════════════════════════════════════════════════════════════════════

/-- Check if variant is compatible with task -/
def isVariantCompatible (variant : GemmaVariant) (task : GemmaTask) : Bool :=
  let needsAudio := requiresAudio task
  let hasAudio := supportsAudio variant
  let needsMultimodal := requiresMultimodal task
  let isMoE := isMoEModel variant
  
  -- Audio tasks require audio support
  if needsAudio ∧ ¬hasAudio then
    false
  -- Multimodal tasks prefer non-MoE for consistency
  else if needsMultimodal ∧ isMoE then
    false
  else
    true

/-- Get recommended variant for task -/
def getRecommendedVariant (task : GemmaTask) : GemmaVariant :=
  if requiresAudio task then
    GemmaVariant.e4B  -- E4B has audio support
  else if requiresMultimodal task then
    GemmaVariant.e4B  -- E4B is recommended default
  else
    GemmaVariant.e4B  -- E4B is default for all tasks

-- ═══════════════════════════════════════════════════════════════════════════
-- ═══════════════════════════════════════════════════════════════════════════
-- §5  Performance Metrics
-- ═══════════════════════════════════════════════════════════════════════════

structure PerformanceMetrics where
  variant : GemmaVariant
  totalTasks : Nat
  avgLatency : Q16_16  -- in seconds
  avgTokensPerSecond : Q16_16
  lastUpdated : Nat
  deriving Repr, Inhabited

structure MetricsRegistry where
  metrics : List PerformanceMetrics
  deriving Repr, Inhabited

/-- Initialize empty metrics registry -/
def initMetricsRegistry : MetricsRegistry :=
  { metrics := [] }

/-- Update performance metrics for variant -/
def updateMetrics (registry : MetricsRegistry) (variant : GemmaVariant) (latency tokensPerSec : Q16_16) (currentTime : Nat) : MetricsRegistry :=
  match registry.metrics.find? (·.variant = variant) with
  | some existing =>
    let newTotal := existing.totalTasks + 1
    let newLatency := Q16_16.ofFrac (existing.avgLatency.raw.toNat + latency.raw.toNat) (existing.totalTasks + 1)
    let newTps := Q16_16.ofFrac (existing.avgTokensPerSecond.raw.toNat + tokensPerSec.raw.toNat) (existing.totalTasks + 1)
    let newMetric := { variant := variant, totalTasks := newTotal, avgLatency := newLatency, avgTokensPerSecond := newTps, lastUpdated := currentTime }
    let newMetrics := registry.metrics.map (fun m => if m.variant = variant then newMetric else m)
    { registry with metrics := newMetrics }
  | none =>
    let newMetric := { variant := variant, totalTasks := 1, avgLatency := latency, avgTokensPerSecond := tokensPerSec, lastUpdated := currentTime }
    { registry with metrics := newMetric :: registry.metrics }

/-- Get metrics for specific variant -/
def getVariantMetrics (registry : MetricsRegistry) (variant : GemmaVariant) : Option PerformanceMetrics :=
  registry.metrics.find? (·.variant = variant)

-- ═══════════════════════════════════════════════════════════════════════════
-- §6  Theorems
-- ═══════════════════════════════════════════════════════════════════════════

/-- E4B variant supports audio -/
theorem e4BSupportsAudio : supportsAudio GemmaVariant.e4B = true := by
  rfl

/-- E4B variant is not MoE -/
theorem e4BIsNotMoE : isMoEModel GemmaVariant.e4B = false := by
  rfl

/-- Audio transcription task requires audio -/
theorem audioTranscriptionRequiresAudio : requiresAudio GemmaTask.audioTranscription = true := by
  rfl

/-- E4B is compatible with text generation -/
theorem e4BCompatibleWithTextGen : isVariantCompatible GemmaVariant.e4B GemmaTask.textGeneration = true := by
  rfl

/-- Empty metrics registry has no metrics -/
theorem emptyRegistryHasNoMetrics : (initMetricsRegistry).metrics.length = 0 := by
  rfl

-- ═══════════════════════════════════════════════════════════════════════════
-- ═══════════════════════════════════════════════════════════════════════════
-- §7  Example Usage
-- ═══════════════════════════════════════════════════════════════════════════

#eval gemmaVariantSize GemmaVariant.e4B
#eval supportsAudio GemmaVariant.e2B
#eval isMoEModel GemmaVariant.e26B_A4B
#eval requiresAudio GemmaTask.audioTranscription
#eval requiresMultimodal GemmaTask.multimodalProcessing
#eval isVariantCompatible GemmaVariant.e4B GemmaTask.textGeneration
#eval getRecommendedVariant GemmaTask.audioTranscription

#eval let registry := initMetricsRegistry
      let registry2 := updateMetrics registry GemmaVariant.e4B (Q16_16.ofFrac 150 100) (Q16_16.ofFrac 50 1) 1000
      getVariantMetrics registry2 GemmaVariant.e4B

end Semantics.GemmaIntegration
