chatikbot/scraping.lisp

(in-package :cl-user)
(defpackage chatikbot.scraping
  (:use :cl :chatikbot.common)
  (:export :*cookie-jar*
           :*current-dom*
           :*current-status*
           :*current-headers*
           :*current-uri*
           :do-request
           :do-form
           :have-cookies
           :with-request
           :with-chat-cookies
           :scrape-list))
(in-package :chatikbot.scraping)

(defvar *cookie-jar* (cl-cookie:make-cookie-jar) "Currently active cookies")
(defvar *current-dom* nil "Currently active request dom")
(defvar *current-status* nil "Currently active request status")
(defvar *current-headers* nil "Currently active request headers")
(defvar *current-uri* nil "Currently active request uri")

(defun apply-context (template context)
  (sublis context template))

(defun do-request (template &optional context)
  (let ((args (apply-context template context)))
    (apply 'xml-request `(,@args :cookie-jar ,*cookie-jar*))))

(defmacro with-request ((template &optional context) &body body)
  `(multiple-value-bind (*current-dom* *current-status* *current-headers* *current-uri*)
       (do-request ,template ,context)
     (declare (ignorable *current-dom* *current-status* *current-headers* *current-uri*))
     ,@body))

(defmacro with-chat-cookies ((chat-id chat-cookies) &body body)
  (alexandria:with-gensyms (g-chat g-cookies)
    `(let* ((,g-chat ,chat-id)
            (,g-cookies ,chat-cookies)
            (*cookie-jar* (or (gethash ,g-chat ,g-cookies)
                              (setf (gethash ,g-chat ,g-cookies)
                                    (cl-cookie:make-cookie-jar)))))
       ,@body)))

(defun node-full-url (node attr &optional (uri *current-uri*))
  (quri:render-uri (quri:merge-uris (quri:uri (plump:attribute node attr)) uri)))

(defun do-validate (info &optional (dom *current-dom*))
  (cond
    ((null info) t)
    (t (not (zerop (length (clss:select info dom)))))))

(defun do-form (form-info &optional context validate)
  (when form-info
    (destructuring-bind (request selector template) form-info
      (with-request (request context)
        (let ((form (clss:select selector *current-dom*)))
          (unless (zerop (length form))
            (let* ((form (elt form 0))
                   (action (node-full-url form "action"))
                   (method (or (keyify (plump:attribute form "method")) :get))
                   (content (append (apply-context template context)
                                    (loop for input across (clss:select "input,select" form)
                                       for name = (plump:attribute input "name")
                                       for value = (plump:attribute input "value")
                                       when name
                                       unless (agets template name)
                                       collect (cons name value))))
                   (action-request `(,action :method ,method :content ,content)))
              (with-request (action-request)
                (unless (do-validate validate)
                  (error "validate error"))
                (values *current-dom* *current-status* *current-headers* *current-uri*)))))))))

(defun have-cookies (request)
  (let ((uri (quri:uri (car request))))
    (cl-cookie:cookie-jar-host-cookies
     *cookie-jar* (quri:uri-host uri) (or (quri:uri-path uri) "/")
     :securep (string= (quri:uri-scheme uri) "https"))))

(defun extract-from-node (node template &optional (uri *current-uri*))
  (destructuring-bind (selector &optional post) template
    (let* ((nodes (clss:select selector node))
           (node (and (not (zerop (length nodes)))
                      (elt nodes 0))))
      (when node
        (cond
          ((eq :href post) (node-full-url node "href" uri))
          ((stringp post) (plump:attribute node post))
          (t (unspacify (text-with-cdata node))))))))

(defun extract-info (items-selector info-templates &key limit (dom *current-dom*) (uri *current-uri*))
  (let ((nodes (clss:select items-selector dom)))
    (when limit
      (setf nodes (subseq nodes 0 (min limit (length nodes)))))
    (loop for node across nodes
       collect (loop for (key . template) in info-templates
                  collect (cons key (extract-from-node node template uri))))))

(defun scrape-list (info &optional context)
  (let* ((scrape (agets info :scrape))
         (request (agets scrape :request))
         (init (agets info :init))
         (validate (agets info :validate)))
    (labels ((return-info ()
               (extract-info (agets scrape :items)
                             (agets scrape :info))))
      (unless (have-cookies request)
        (do-form init context validate))
      (with-request (request context)
        (if (do-validate validate)
            (return-info)
            (progn
              (do-form init context validate)
              (with-request (request context)
                (return-info))))))))