(in-package :passepartout)

(defvar *embedding-provider* :trigram
  "Active embedding provider: :trigram, :sha256, :local, :openai, :native.")

(defvar *embedding-queue* nil
  "Queue of text objects awaiting embedding.")

(defvar *embedding-batch-size* 10
  "Maximum texts per embedding API call.")

(defun embedding-backend-local (text)
  "Generate embeddings via a local OpenAI-compatible endpoint."
  (let* ((url (or (uiop:getenv "LOCAL_BASE_URL") (format nil "http://~a" (or (uiop:getenv "OLLAMA_HOST") "localhost:11434"))))
         (model (or (uiop:getenv "EMBEDDING_MODEL") "nomic-embed-text"))
         (body (cl-json:encode-json-to-string
                `((model . ,model) (input . ,text)))))
    (handler-case
        (let* ((response (dex:post (format nil "~a/api/embeddings" url)
                                   :headers '(("Content-Type" . "application/json"))
                                   :content body :connect-timeout 5 :read-timeout 30))
               (json (cl-json:decode-json-from-string response))
               (data (car (cdr (assoc :data json)))))
          (or (cdr (assoc :embedding data))
              (list :error "No embedding in response")))
      (error (c)
        (list :error (format nil "Embedding failed: ~a" c))))))

(defun embedding-backend-openai (text)
  "Generate embeddings via OpenAI compatible /v1/embeddings endpoint."
  (let* ((api-key (uiop:getenv "OPENAI_API_KEY"))
         (base-url (or (uiop:getenv "EMBEDDING_BASE_URL") "https://api.openai.com/v1"))
         (model (or (uiop:getenv "EMBEDDING_MODEL") "text-embedding-3-small"))
         (body (cl-json:encode-json-to-string
                `((model . ,model) (input . ,text)))))
    (handler-case
        (let* ((response (dex:post (format nil "~a/embeddings" base-url)
                                    :headers `(("Content-Type" . "application/json")
                                               ("Authorization" . ,(format nil "Bearer ~a" api-key)))
                                    :content body :connect-timeout 5 :read-timeout 30))
               (json (cl-json:decode-json-from-string response))
               (data (car (cdr (assoc :data json)))))
          (or (cdr (assoc :embedding data))
              (list :error "No embedding in response")))
      (error (c)
        (list :error (format nil "OpenAI Embedding failed: ~a" c))))))

(defun embedding-backend-sha256 (text)
  "SHA-256 based vector — integrity only, no semantic retrieval capability.
For environments where even trivial computation is undesirable."
  (let* ((digest (ironclad:digest-sequence :sha256 (babel:string-to-octets text)))
         (vec (make-array 8 :element-type 'single-float :initial-element 0.0)))
    (dotimes (i (min (length digest) 8))
      (setf (aref vec i) (float (/ (aref digest i) 255.0) 0.0)))
    vec))

(defun embedding-backend-hashing (text)
  "Backward-compatibility alias for SHA-256 hashing."
  (embedding-backend-sha256 text))

(defun embedding-backend-trigram (text)
  "Trigram bloom filter — captures lexical overlap for semantic retrieval.
Returns a 128-dim float vector where each position corresponds to a trigram hash.
Pure Lisp, zero external dependencies, works fully offline."
  (let* ((s (string-trim '(#\Space #\Newline #\Tab) (string-downcase text)))
         (trigrams (make-hash-table :test 'equal))
         (result (make-array 128 :element-type 'single-float :initial-element 0.0)))
    (when (>= (length s) 3)
      (loop for i from 0 to (- (length s) 3)
            for tri = (subseq s i (+ i 3))
            do (setf (gethash tri trigrams) t)))
    (maphash (lambda (tri _) (declare (ignore _))
               (setf (aref result (mod (sxhash tri) 128)) 1.0))
             trigrams)
    result))

(defvar *embedding-backend* nil
  "Explicit backend override (nil = use *embedding-provider*).")

(defun embeddings-compute (text)
  "Compute an embedding vector for text using the active backend."
  (embed-object text))

(defun embed-object (text)
  "Embed a single text string using the active backend."
  (let* ((selected (or *embedding-backend* *embedding-provider* :trigram))
         (backend (case selected
                    (:local #'embedding-backend-local)
                    (:openai #'embedding-backend-openai)
                    (:native
                     (unless (fboundp 'embedding-backend-native)
                       (embedding-native-ensure-loaded))
                     #'embedding-backend-native)
                    (:sha256 #'embedding-backend-sha256)
                    (t #'embedding-backend-trigram))))
    (if backend
        (progn
          (log-message "EMBEDDING: Provider ~a, backend=~a" selected backend)
          (funcall backend text))
        (progn
          (log-message "EMBEDDING: No backend for provider ~a, using hashing" selected)
          (embedding-backend-hashing text)))))

(defun embed-queue-object (object)
  "Queue a text object for async embedding."
  (push object *embedding-queue*)
  (log-message "EMBEDDING: Queued object"))

(defun embed-all-pending ()
  "Drain the embedding queue, store vectors in the store-keyed objects."
  (let ((batch (nreverse *embedding-queue*)))
    (setf *embedding-queue* nil)
    (dolist (item batch)
      (handler-case
          (let ((id (getf item :id))
                (text (getf item :text)))
            (when (and id text)
              (let ((vec (embeddings-compute text))
                    (obj (gethash id *memory-store*)))
                (when (and obj vec (not (listp vec)))
                  (setf (memory-object-vector obj) vec))
                (log-message "EMBEDDING: Computed vector for ~a (~d dims)" id (length vec)))))
        (error (c)
          (log-message "EMBEDDING: Failed to embed object: ~a" c))))))

;; Apply env var override at load time
(let ((provider-env (uiop:getenv "EMBEDDING_PROVIDER")))
  (when provider-env
    (let ((kw (intern (string-upcase provider-env) :keyword)))
      (setf *embedding-provider* kw)
      (log-message "EMBEDDING: Set provider to ~a from EMBEDDING_PROVIDER env" kw))))

(defun embedding-native-ensure-loaded ()
  "Lazy-load the native CFFI backend. First call blocks ~30s for model init."
  (when (fboundp 'embedding-backend-native)
    (return-from embedding-native-ensure-loaded t))
  (let* ((data-dir (uiop:ensure-directory-pathname
                    (or (uiop:getenv "PASSEPARTOUT_DATA_DIR")
                        (namestring (merge-pathnames ".local/share/passepartout/"
                                                    (user-homedir-pathname))))))
         (native-file (merge-pathnames "lisp/embedding-native.lisp" data-dir)))
    (handler-case
        (progn
          (load native-file :verbose nil :print nil)
          (log-message "EMBEDDING: Native backend loaded from ~a" native-file))
      (error (c)
        (error "Failed to load native embedding backend (~a): ~a" native-file c)))))

;; Preload native model if configured at startup
(when (eq *embedding-provider* :native)
  (log-message "EMBEDDING: Native provider configured, preloading model...")
  (embedding-native-ensure-loaded)
  (handler-case
      (progn
        (embedding-native-load-model)
        (log-message "EMBEDDING: Native model preloaded (~d dims)"
                     (embedding-native-get-dim)))
    (error (c)
      (log-message "EMBEDDING: Preload deferred: ~a (will retry on first call)" c))))

(log-message "EMBEDDING: Gateway loaded with provider ~a" *embedding-provider*)

(defun mark-vector-stale (id &optional content)
  "Mark a memory object's vector as :pending and queue it for re-embedding.
When content is not supplied, reads from the object in *memory-store*."
  (let* ((obj (gethash id *memory-store*))
         (text (or content (and obj (memory-object-content obj)))))
    (when obj
      (setf (memory-object-vector obj) :pending))
    (when text
      (push (list :id id :text text) *embedding-queue*)
      (log-message "EMBEDDING: Marked ~a vector stale, queued for re-embed" id))
    (or obj text)))

(defskill :passepartout-embedding-backends
  :priority 70
  :trigger (lambda (ctx) (declare (ignore ctx)) nil))

;; Register periodic batch embedding via cron (when orchestrator available)
(when (fboundp 'orchestrator-register-cron)
  (handler-case
      (orchestrator-register-cron :embed-batch
                                  "<2026-05-05 Tue +10m>"
                                  'embed-all-pending
                                  :reflex)
    (error (c)
      (log-message "EMBEDDING: Cron registration failed: ~a" c))))

(eval-when (:compile-toplevel :load-toplevel :execute)
  (ql:quickload :fiveam :silent t))

(defpackage :passepartout-embedding-tests
  (:use :cl :passepartout)
  (:export #:embedding-suite))

(in-package :passepartout-embedding-tests)

(fiveam:def-suite embedding-suite :description "Embedding gateway verification")
(fiveam:in-suite embedding-suite)

(fiveam:test test-embedding-backend-hashing
  "Contract 2: hashing backend produces 8-element float vector."
  (let ((vec (embedding-backend-hashing "hello world")))
    (fiveam:is (arrayp vec))
    (fiveam:is (= 8 (length vec)))
    (fiveam:is (every #'numberp (coerce vec 'list)))))

(fiveam:test test-embedding-backend-hashing-deterministic
  "Contract 2: same input produces same vector."
  (let ((v1 (embedding-backend-hashing "test"))
        (v2 (embedding-backend-hashing "test")))
    (fiveam:is (equalp v1 v2))))

(fiveam:test test-embeddings-compute
  "Contract 1: embeddings-compute returns a float vector."
  (let ((vec (embeddings-compute "some text")))
    (fiveam:is (arrayp vec))
    (fiveam:is (> (length vec) 0))))

(fiveam:test test-embed-queue-and-drain
  "Contract 3: embed-all-pending drains queue and stores vectors."
  (let ((*embedding-queue* nil))
    (embed-queue-object '(:id "test-obj" :text "sample text"))
    (fiveam:is (= 1 (length *embedding-queue*)))
    (embed-all-pending)
    (fiveam:is (null *embedding-queue*))))

(fiveam:test test-mark-vector-stale
  "Contract 4: mark-vector-stale sets vector to :pending and queues for re-embed."
  (let ((*embedding-queue* nil))
    ;; Create an object in memory with a vector
    (let ((obj (make-memory-object :id "stale-test" :content "stale content"
                                   :vector #(1.0 2.0 3.0))))
      (setf (gethash "stale-test" *memory-store*) obj)
      (mark-vector-stale "stale-test")
      (fiveam:is (eq :pending (memory-object-vector obj)))
      (fiveam:is (= 1 (length *embedding-queue*)))
      (let ((item (first *embedding-queue*)))
        (fiveam:is (string= "stale-test" (getf item :id)))
        (fiveam:is (string= "stale content" (getf item :text))))
      ;; Clean up
      (remhash "stale-test" *memory-store*))))