;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;                                                                  ;;;

;;; Free Software published under an MIT-like license. See LICENSE   ;;;

;;;                                                                  ;;;

;;; Copyright (c) 2012 Google, Inc.  All rights reserved.            ;;;

;;;                                                                  ;;;
;;; Original author: Scott McKay                                     ;;;
;;;                                                                  ;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(in-package "PROTO-IMPL")


;;; Protocol buffer generation from ordinary CLOS classes

;; Controls whether or not to use ':alias-for' for the Protobuf generated
;; for an existing Lisp class
;; The default is presently true because, at least initially, we'll be using
;; the generated Protobufs code in the Lisp world that includes that classes
;; from which the code was generated
(defvar *alias-existing-classes* t)

;; Doing this can't really work perfectly, there's not enough information
;;  - How do we decide if there's an ownership hierarchy that should produce embedded messages?
;;  - How do we decide if there are volatile slots that should not be included in the message?

(defun write-schema-for-classes (classes
                                 &key (stream *standard-output*) (type :proto)
                                      name package lisp-package install
                                      slot-filter type-filter enum-filter value-filter
                                      (alias-existing-classes *alias-existing-classes*))

  "Given a set of CLOS classes, generates a Protobufs schema for the classes
   and pretty prints the schema to the stream.
   The return value is the schema."

  (let ((schema (generate-schema-for-classes classes
                  :name name
                  :package package
                  :lisp-package (or lisp-package package)
                  :install install
                  :slot-filter slot-filter
                  :type-filter type-filter
                  :enum-filter enum-filter
                  :value-filter value-filter
                  :alias-existing-classes alias-existing-classes)))

    (fresh-line stream)

    (write-schema schema :stream stream :type type)

    (terpri stream)

    schema))

(defun generate-schema-for-classes (classes
                                    &key name package lisp-package install
                                         slot-filter type-filter enum-filter value-filter
                                         (alias-existing-classes *alias-existing-classes*))

  "Given a set of CLOS classes, generates a Protobufs schema for the classes.
   The return value is the schema."

  (let* ((*alias-existing-classes* alias-existing-classes)
         (package  (and package (if (stringp package) package (string-downcase (string package)))))

         (lisp-pkg (string (or lisp-package package)))

         (schema   (make-instance 'protobuf-schema

                     :name name

                     :package package
                     :lisp-package lisp-pkg

                     :syntax "proto2"))

         (*protobuf* schema)
         (*protobuf-package* (or (find-proto-package lisp-pkg) *package*))

         (messages (mapcar #'(lambda (c)

                               (class-to-protobuf-message c schema

                                :slot-filter slot-filter
                                :type-filter type-filter
                                :enum-filter enum-filter
                                :value-filter value-filter))
                           classes)))

    (setf (proto-messages schema) messages)
    (when install
      (record-protobuf schema)
      (with-collectors ((messages collect-message))
        (labels ((collect-messages (message)
                   (collect-message message)
                   (map () #'collect-messages (proto-messages message))))
          (map () #'collect-messages (proto-messages schema)))
        (map () #'record-protobuf messages)))
    schema))

(defun class-to-protobuf-message (class schema

                                  &key slot-filter type-filter enum-filter value-filter)

  "Given a CLOS class, return a Protobufs model object for it."

  (let* ((class (let ((c (find-class class)))
                  (unless (class-finalized-p c)
                    (finalize-inheritance c))           ;so the rest of the MOP will work
                  c))

         (slots (class-slots class)))

    (with-collectors ((enums  collect-enum)

                      (msgs   collect-msg)

                      (fields collect-field))

      (loop with index = 1
            for s in slots doing
        (multiple-value-bind (field msg enum)

            (slot-to-protobuf-field class s index slots

              :slot-filter slot-filter
              :type-filter type-filter
              :enum-filter enum-filter
              :value-filter value-filter)

          (when enum
            (collect-enum enum))

          (when msg
            (collect-msg msg))

          (when field

            (incf index 1)                              ;don't worry about the 19000-19999 restriction

            (collect-field field))))

      (let* ((cname (class-name class))
             (pname (class-name->proto cname))
             (message
              ;;--- Making the message this late means its children won't
              ;;--- have the right qualified names
              (make-instance 'protobuf-message
                :class cname
                :name  pname
                :qualified-name (make-qualified-name *protobuf* pname)
                :parent schema
                :alias-for (and *alias-existing-classes* cname)
                :enums    (delete-duplicates enums :key #'proto-name :test #'string=)
                :messages (delete-duplicates msgs :key #'proto-name :test #'string=)
                :fields   fields))
             (*protobuf* message))

        ;; Give every child a proper parent
        (dolist (enum (proto-enums message))
          (setf (proto-parent enum) message))
        (dolist (msg (proto-messages message))
          (setf (proto-parent msg) message))
        (dolist (field (proto-fields message))
          (setf (proto-parent field) message))
        message))))

;; Returns a field, (optionally) an inner message, and (optionally) an inner enum

(defun slot-to-protobuf-field (class slot index slots
                               &key slot-filter type-filter enum-filter value-filter)

  "Given a CLOS slot, return a Protobufs model object for it."

  (when (or (null slot-filter)
            (funcall slot-filter slot slots))

    (multiple-value-bind (expanded-type unexpanded-type)
       (find-slot-definition-type class slot)
      (multiple-value-bind (type pclass packed enums)
          (clos-type-to-protobuf-type expanded-type type-filter enum-filter)

        (multiple-value-bind (reqd vectorp)
            (clos-type-to-protobuf-required (find-slot-definition-type class slot) type-filter)
          (let* ((ename (and enums
                             (if (and unexpanded-type (symbolp unexpanded-type))
                               (symbol-name unexpanded-type)
                               (format nil "~A-~A" 'enum (slot-definition-name slot)))))
                 (etype (and enums
                             (if (and unexpanded-type (symbolp unexpanded-type))
                               unexpanded-type
                               (intern ename (symbol-package (slot-definition-name slot))))))
                 (enum  (and enums
                             (let* ((names (mapcar #'enum-name->proto enums))
                                    (prefix (and (> (length names) 1)
                                                 (subseq (first names)
                                                         0 (mismatch (first names) (car (last names)))))))
                               (when (and prefix (> (length prefix) 2)
                                          (every #'(lambda (name) (starts-with name prefix)) names))
                                 (setq names (mapcar #'(lambda (name) (subseq name (length prefix))) names)))
                               (unless (and unexpanded-type (symbolp unexpanded-type))
                                 #+ignore         ;this happens constantly, the warning is not useful
                                 (protobufs-warn "Use DEFTYPE to define a MEMBER type instead of directly using ~S"
                                                 expanded-type))

                               (let* ((pname (class-name->proto ename))
                                      (enum

                                       (make-instance 'protobuf-enum
                                         :class etype

                                         :name  pname
                                         :qualified-name (make-qualified-name *protobuf* pname)
                                         :parent *protobuf*))

                                      (values
                                       (loop for name in names
                                             for val in enums
                                             for index upfrom 0
                                             collect (make-instance 'protobuf-enum-value
                                                       :name name

                                                       :qualified-name (make-qualified-name enum name)

                                                       :index index
                                                       :value val
                                                       :parent enum))))
                                 (setf (proto-values enum) values)
                                 enum))))

                 (default (if (slot-definition-initfunction slot)
                            (clos-init-to-protobuf-default
                             (slot-definition-initform slot) expanded-type value-filter)
                            (if (eq reqd :repeated)
                              (if vectorp $empty-vector $empty-list)
                              $empty-default)))
                 (field   (make-instance 'protobuf-field
                            :name  (slot-name->proto (slot-definition-name slot))
                            :type  (if enum (class-name->proto ename) type)
                            :class (if enum etype pclass)
                            :required reqd

                            :index  index
                            :value  (slot-definition-name slot)
                            :reader (let ((reader (find-slot-definition-reader class slot)))
                                      ;; Only use the reader if it is "interesting"
                                      (unless (string= (symbol-name reader)
                                                       (format nil "~A-~A" 
                                                               (class-name class) (slot-definition-name slot)))
                                        reader))

                            :default default
                            :packed  packed)))
            (values field nil enum)))))))

(defun find-slot-definition-type (class slotd)

  "Given a class and a slot descriptor, find the \"best\" type definition for the slot."

  (let* ((slot-name    (slot-definition-name slotd))
         (direct-slotd (some #'(lambda (c)
                                 (find slot-name (class-direct-slots c) :key #'slot-definition-name))
                             (class-precedence-list class))))

    (if direct-slotd

      ;; The direct slotd will have an unexpanded definition
      ;; Prefer it for 'list-of' so we can get the base type

      (let ((type (slot-definition-type direct-slotd))
            (quux-list-of (and (find-package :quux)
                               (intern "LIST-OF" (find-package :quux)))))
        (values (if (and (listp type) (member (car type) `(list-of vector-of ,quux-list-of)))

                  type
                  (slot-definition-type slotd))
                (if (symbolp type)
                  type
                  (when (and (listp type)

                             (eq (car type) 'or)

                             (member 'null (cdr type)))
                    (find-if-not #'(lambda (s) (eq s 'null)) (cdr type))))))
      (values (slot-definition-type slotd) nil))))

(defun find-slot-definition-reader (class slotd)

  "Given a class and a slot descriptor, find the name of a reader method for the slot."

  (let* ((slot-name    (slot-definition-name slotd))
         (direct-slotd (some #'(lambda (c)
                                 (find slot-name (class-direct-slots c) :key #'slot-definition-name))
                             (class-precedence-list class))))
    (and direct-slotd (first (slot-definition-readers direct-slotd)))))

(defun clos-type-to-protobuf-type (type &optional type-filter enum-filter)

  "Given a Lisp type, returns a Protobuf type, a class or primitive type,
   whether or not to pack the field, and (optionally) a set of enum values."

  (let ((type (if type-filter (funcall type-filter type) type))
        ;; Hideous, but useful, kludge for those of us at ITA-by-Google
        (quux-list-of (and (find-package :quux)
                           (intern "LIST-OF" (find-package :quux)))))

    (flet ()

      (if (listp type)
        (destructuring-bind (head &rest tail) type
          (case head
            ((or)
             (when (or (> (length tail) 2)
                       (not (member 'null tail)))

               (protobufs-warn "The OR type ~S is too complicated, proceeding anyway" type))

             (if (eq (first tail) 'null)
               (clos-type-to-protobuf-type (second tail))
               (clos-type-to-protobuf-type (first tail))))
            ((and)

             (cond ((and quux-list-of
                         (ignore-errors
                          (subtypep type `(,quux-list-of t))))
                    ;; Special knowledge of 'quux:list-of', which uses (and list (satisfies <t>))

                    (let* ((satisfies (find 'satisfies tail :key #'car))
                           (pred (second satisfies))
                           (type (if (starts-with (string pred) "LIST-OF-")
                                   (intern (subseq (string pred) #.(length "LIST-OF-")) (symbol-package pred))
                                   pred)))
                      (multiple-value-bind (type class)

                          (lisp-type-to-protobuf-type type)

                        (values type class (packed-type-p class)))))
                   (t
                    (let ((new-tail (remove-if #'(lambda (x) (and (listp x) (eq (car x) 'satisfies))) tail)))

                      (when (> (length new-tail) 1)

                        (protobufs-warn "The AND type ~S is too complicated, proceeding anyway" type))

                      (lisp-type-to-protobuf-type (first tail))))))

            ((member)                           ;maybe generate an enum type
             (if (or (equal type '(member t nil))
                     (equal type '(member nil t)))
               (values "bool" :bool)
               (let ((values (if enum-filter (funcall enum-filter tail) tail)))
                 (cond ((every #'(lambda (x)
                                   (or (null x) (characterp x) (stringp x))) values)
                        (values "string" :string))
                       ((every #'(lambda (x)
                                   (or (null x) (and (integerp x) (>= x 0)))) values)
                        (values "uint32" :uint32))
                       ((every #'(lambda (x)
                                   (or (null x) (integerp x))) values)
                        (values "int32" :int32))

                       ((every #'(lambda (x) (symbolp x)) values)

                        (let ((values (remove-if #'null values)))

                          (values (class-name->proto (format nil "~A" type))

                                  type
                                  nil           ;don't pack enums

                                  (if enum-filter (funcall enum-filter values) values))))
                       (t
                        (error "The MEMBER type ~S is too complicated" type))))))

            ((list-of vector-of)

             (multiple-value-bind (type class)

                 (lisp-type-to-protobuf-type (first tail))

               (values type class (packed-type-p class))))
            ((integer)
             (let ((lo (or (first tail) '*))
                   (hi (or (second tail) '*)))
               (if (or (eq lo '*) (< lo 0))
                 (if (eq hi '*)
                   (values "int64" :int64)
                   (if (<= (integer-length hi) 32)
                     (values "int32" :int32)
                     (values "int64" :int64)))
                 (if (eq hi '*)
                   (values "uint64" :uint64)
                   (if (<= (integer-length hi) 32)
                     (values "uint32" :uint32)
                     (values "uint64" :uint64))))))
            ((signed-byte)
             (let ((len (first tail)))
               (if (<= len 32)
                 (values "int32" :int32)
                 (values "int64" :int64))))
            ((unsigned-byte)
             (let ((len (first tail)))
               (if (<= len 32)
                 (values "uint32" :uint32)
                 (values "uint64" :uint64))))

            ((float single-float double-float)

             (lisp-type-to-protobuf-type head))

            (otherwise

             (if (eq head quux-list-of)
               (multiple-value-bind (type class)

                   (lisp-type-to-protobuf-type (first tail))

                 (values type class (packed-type-p class)))

               (lisp-type-to-protobuf-type type)))))
        (lisp-type-to-protobuf-type type)))))

(defun lisp-type-to-protobuf-type (type)
  (case type
    ((int32)    (values "int32" :int32))
    ((int64)    (values "int64" :int64))
    ((uint32)   (values "uint32" :uint32))
    ((uint64)   (values "uint64" :uint64))
    ((sint32)   (values "sint32" :sint32))
    ((sint64)   (values "sint64" :sint64))
    ((fixed32)  (values "fixed32" :fixed32))
    ((fixed64)  (values "fixed64" :fixed64))
    ((sfixed32) (values "sfixed32" :sfixed32))
    ((sfixed64) (values "sfixed64" :sfixed64))
    ((integer)  (values "int64" :int64))
    ((single-float float)
     (values "float" :float))
    ((double-float)
     (values "double" :double))
    ((boolean)
     (values "bool" :bool))
    ((symbol keyword)
     (values "string" :symbol))
    (otherwise
     (cond ((ignore-errors
             (or (eql type 'symbol)
                 (subtypep type '(or string character))))
            (values "string" :string))
           ((ignore-errors
             (subtypep type 'byte-vector))
            (values "bytes" :bytes))
           (t
            (values (class-name->proto type) type))))))

(defun packed-type-p (type)
  "Returns true if the given Protobufs type can use a packed field."
  (not (null (member type '(:int32 :int64 :uint32 :uint64 :sint32 :sint64
                            :fixed32 :fixed64 :sfixed32 :sfixed64

                            :bool :float :double)))))

(defun clos-type-to-protobuf-required (type &optional type-filter)

  "Given a Lisp type, returns a \"cardinality\": :required, :optional or :repeated.
   If the sceond returned value is true, it's a repeated field that should use a vector."

  (let ((type (if type-filter (funcall type-filter type) type))
        (quux-list-of (and (find-package :quux)
                           (intern "LIST-OF" (find-package :quux)))))

    (if (listp type)
      (destructuring-bind (head &rest tail) type
        (case head
          ((or)

           (let ((optional (member 'null tail))
                 (repeated (find-if #'(lambda (r)
                                        (eq (clos-type-to-protobuf-required r) :repeated)) tail)))
             (if repeated
               (clos-type-to-protobuf-required repeated)
               (values (if optional :optional :required) nil))))

          ((and)

           (cond ((or (subtypep type '(list-of t))

                      (and quux-list-of (subtypep type `(,quux-list-of t))))

                  (values :repeated nil))
                 ((subtypep type '(vector-of t))
                  (values :repeated t))
                 (t
                  (values :required nil))))

          ((member)
           (if (or (equal type '(member t nil))
                   (equal type '(member nil t)))

             (values :required nil)
             (values (if (member nil tail) :optional :required) nil)))

          ((list-of)

           (values :repeated nil))
          ((vector-of)
           (values :repeated t))

          (otherwise

           (if (eq head quux-list-of)
             (values :repeated nil)
             (values :required nil)))))

      (values :required nil))))

(defun clos-init-to-protobuf-default (value type &optional value-filter)

  "Given an initform and a Lisp type, returns a plausible default value.
   Don't call this if the default is empty, because that will confuse 'nil' with 'unbound'."

  (let ((value (if value-filter (funcall value-filter value) value)))

    (and (constantp value)
         (ignore-errors (typep value type))

         (values value t))))

(defun protobuf-default-to-clos-init (default type)

  "Given a Protobufs type and default, return a CLOS initform value.
   Don't call this if the default is empty, because that will confuse 'nil' with 'unbound'."

  (cond ((ignore-errors (typep default type))
         default)
        ((symbolp default)
         (cond ((eq type :bool)

                (boolean-true-p default))
               ;; If we've got a symbol, it must be to initialize an enum type
               ;; whose values are represented by keywords in Lisp
               (t (kintern (symbol-name default)))))

        ((stringp default)
         (cond ((eq type :bool)
                (boolean-true-p default))
               ((member type '(:int32 :uint32 :int64 :uint64 :sint32 :sint64
                               :fixed32 :sfixed32 :fixed64 :sfixed64))
                (let ((default (read-from-string default)))
                  (and (integerp default) default)))
               ((member type '(:float :double))
                (let ((default (read-from-string default)))
                  (and (floatp default) default)))
               (t default)))))