;; SKC-LISP: JIT Compiler Integration (Phase 3D-2)
;; ClojureScript wrapper for Cranelift backend

(ns snapkitty.lisp.jit
  (:require
    [snapkitty.lisp.emojiscript :as emoji]
    [snapkitty.lisp.crypto :as crypto]
    [snapkitty.lisp.worm :as worm]))

;; ============================================================================
;; JIT Compilation Pipeline
;; ============================================================================

(defn compile-with-proof
  "Compile EmojiScript to native code using proof certificate.

   Args:
     source: EmojiScript source code string
     proof-certificate: ProofCertificate (Blake3 + Ed25519 signed)
     target: 'x86_64' or 'aarch64'

   Returns:
     {:native-code <bytes>
      :proof-id <u32>
      :performance-estimate <ns>}"
  [source proof-certificate target]
  (let [;; Step 1: Compile EmojiScript to bytecode
        bytecode (emoji/compile-emojiscript source)

        ;; Step 2: Validate proof certificate against bytecode
        validity (validate-proof-cert proof-certificate (:bytecode bytecode))

        ;; Step 3: Check if proof covers bytecode operations
        _ (if-not (:valid? validity)
            (throw (ex-info "Proof does not cover bytecode" validity)))

        ;; Step 4: Extract theorem coverage
        theorems-covered (:theorems-covered proof-certificate)

        ;; Step 5: Compile bytecode → native code (Cranelift backend)
        native-code (jit-compile-cranelift (:bytecode bytecode) target)

        ;; Step 6: Sign machine code with certificate
        signature (crypto/ed25519-sign native-code (:public-key proof-certificate))

        ;; Step 7: Estimate performance
        perf-estimate (estimate-execution-time bytecode target)]

    {:native-code native-code
     :proof-id (:theorem-id proof-certificate)
     :theorems-covered theorems-covered
     :signature signature
     :performance-estimate perf-estimate
     :target target}))

;; ============================================================================
;; Proof Certificate Validation
;; ============================================================================

(defn validate-proof-cert
  "Validate proof certificate against bytecode.

   Returns:
     {:valid? <bool>
      :missing-theorems <list>
      :errors <list>}"
  [cert bytecode]
  (let [errors (atom [])

        ;; Check 1: Certificate structure
        _ (if-not (= (count (:proof-hash cert)) 32)
            (swap! errors conj "Invalid proof_hash size (expected 32 bytes)"))

        ;; Check 2: Signature validation
        sig-valid? (crypto/ed25519-verify
                     bytecode
                     (:signature cert)
                     (:public-key cert))
        _ (if-not sig-valid?
            (swap! errors conj "Ed25519 signature invalid"))

        ;; Check 3: Theorem coverage
        required-ops (extract-required-ops bytecode)
        covered-ops (if (= (:theorems-covered cert) 0)
                     []
                     (get-covered-operations (:theorems-covered cert)))
        missing (clojure.set/difference required-ops covered-ops)
        _ (if-not (empty? missing)
            (swap! errors conj (str "Missing theorem coverage for: " missing)))

        ;; Check 4: Machine state invariants
        invariants-ok? (check-machine-state-invariants
                         (:machine-state-invariants cert))
        _ (if-not invariants-ok?
            (swap! errors conj "Machine state invariants not satisfied"))

        ;; Check 5: Target platform support
        platform-ok? (contains? #{"x86_64" "aarch64"} (:cranelift-backend cert))
        _ (if-not platform-ok?
            (swap! errors conj (str "Unsupported target: " (:cranelift-backend cert))))]

    {:valid? (and sig-valid? invariants-ok? platform-ok? (empty? @errors))
     :missing-theorems missing
     :errors @errors}))

;; ============================================================================
;; Bytecode Operation Extraction
;; ============================================================================

(defn extract-required-ops
  "Extract which theorems are needed to prove bytecode correct."
  [bytecode]
  (let [ops (atom #{})]
    (doseq [byte bytecode]
      (case byte
        ;; Stack/arithmetic: needs T01 (determinism)
        (0x01 0x02 0x03 0x04 0x10 0x11 0x12 0x13)
        (swap! ops conj :T01)

        ;; Comparison/control: needs T01 + T04 (state preservation)
        (0x20 0x21 0x30 0x31)
        (do (swap! ops conj :T01) (swap! ops conj :T04))

        ;; Semantic passes: need T08-T11 (mutation/rollback)
        (0x40 0x41 0x42 0x43)
        (do (swap! ops conj :T08) (swap! ops conj :T10))

        nil))
    @ops))

(defn get-covered-operations
  "Decode theorem bitmask to list of covered theorems."
  [bitmask]
  (let [theorems [:T01 :T02 :T03 :T04 :T05 :T06 :T08 :T09 :T10 :T11]]
    (filterv (fn [[idx thm]]
               (bit-test bitmask idx))
            (map-indexed vector theorems))))

(defn check-machine-state-invariants
  "Verify machine state requirements."
  [invariants]
  (and (bit-test invariants 0)  ;; Stack bounds checked
       (bit-test invariants 1)  ;; Heap bounds checked
       (bit-test invariants 2)  ;; Generation counter valid
       ))

;; ============================================================================
;; Cranelift JIT Backend Integration
;; ============================================================================

(defn jit-compile-cranelift
  "Call Cranelift backend to compile bytecode → native code.

   This is a native binding to cranelift-backend.rs:
   compile_emojiscript_to_native(bytecode, target) → Vec<u8>"
  [bytecode target]
  (let [native-module (js/require "./build/Release/binding.node")]
    ;; In production, this calls the compiled Rust backend
    ;; Placeholder: returns mock native code
    (.compileToNative native-module bytecode target)))

;; ============================================================================
;; Performance Estimation
;; ============================================================================

(defn estimate-execution-time
  "Estimate native code execution time (in nanoseconds).

   Based on bytecode length and operation cost model."
  [bytecode target]
  (let [baseline-ns 50                    ;; Base JIT compilation overhead
        op-cost-ns 10                     ;; Per-operation native cost
        ops-count (count bytecode)
        platform-factor (case target
                         "x86_64" 1.0
                         "aarch64" 1.1
                         1.0)]

    (long (* platform-factor (+ baseline-ns (* ops-count op-cost-ns))))))

;; ============================================================================
;; MCP Tool: compile_with_proof
;; ============================================================================

(defn mcp-compile-with-proof
  "MCP tool interface for compile_with_proof.

   Args:
     source: EmojiScript source code (string)
     proof-certificate: Base64-encoded certificate
     target: 'x86_64' or 'aarch64'

   Returns:
     {:native_code <base64>
      :proof_id <u32>
      :theorems_covered <u32>
      :performance_estimate <ns>}"
  [source proof-cert-b64 target]
  (try
    (let [;; Decode certificate from base64
          cert-bytes (js/Buffer.from proof-cert-b64 "base64")
          cert (deserialize-proof-certificate cert-bytes)

          ;; Compile
          result (compile-with-proof source cert target)

          ;; Encode native code to base64 for transport
          native-b64 (.toString (:native-code result) "base64")]

      {:status "success"
       :native_code native-b64
       :proof_id (:proof-id result)
       :theorems_covered (:theorems-covered result)
       :performance_estimate (:performance-estimate result)})

    (catch js/Error e
      {:status "error"
       :message (.toString e)})))

;; ============================================================================
;; Serialization Helpers
;; ============================================================================

(defn deserialize-proof-certificate
  "Deserialize 157-byte binary proof certificate."
  [buf]
  ;; Binary layout (157 bytes total):
  ;; [0:4]    theorem_id (u32, LE)
  ;; [4:36]   proof_hash (32 bytes)
  ;; [36:40]  theorems_covered (u32, LE)
  ;; [40:44]  machine_state_invariants (u32, LE)
  ;; [44:60]  cranelift_backend (16 bytes, null-padded string)
  ;; [60:61]  optimization_level (u8)
  ;; [61:125] signature (64 bytes)
  ;; [125:157] public_key (32 bytes)

  {:theorem-id (.readUInt32LE buf 0)
   :proof-hash (. buf slice 4 36)
   :theorems-covered (.readUInt32LE buf 36)
   :machine-state-invariants (.readUInt32LE buf 40)
   :cranelift-backend (.toString (.slice buf 44 60) "utf8")
   :optimization-level (.readUInt8 buf 60)
   :signature (. buf slice 61 125)
   :public-key (. buf slice 125 157)})

;; ============================================================================
;; Tests
;; ============================================================================

(defn run-jit-tests []
  (println "Testing JIT compilation...")

  ;; Test 1: Bytecode operation extraction
  (assert (= (extract-required-ops [0x01 0x02 0x03]) #{:T01}))
  (assert (= (extract-required-ops [0x20 0x21]) #{:T01 :T04}))
  (println "✓ Operation extraction")

  ;; Test 2: Proof certificate validation
  (let [cert {:proof-hash (make-array 32)
              :signature (make-array 64)
              :public-key (make-array 32)
              :theorems-covered 0x000F
              :machine-state-invariants 0x7
              :cranelift-backend "x86_64"}
        bytecode [0x01 0x02 0x03 0xFF]
        result (validate-proof-cert cert bytecode)]
    (assert (contains? result :valid?))
    (println "✓ Certificate validation"))

  ;; Test 3: Performance estimation
  (let [perf (estimate-execution-time [0x01 0x02 0x03 0x04 0x05] "x86_64")]
    (assert (> perf 0))
    (println "✓ Performance estimation"))

  (println "All JIT tests passed!"))