#lang web-server/insta

  (require web-server/formlets
           "model-3.rkt")

  ; start: request -> html-response
  ; Consumes a request and produces a page that displays
  ; all of the web content.
  (define (start request)
    (render-blog-page
     (initialize-blog!
      (build-path (current-directory)
                  "the-blog-data.sqlite"))
     request))

  ; new-post-formlet : formlet (values string? string?)
  ; A formlet for requesting a title and body of a post
  (define new-post-formlet
    (formlet
     (#%# ,{input-string . => . title}
          ,{input-string . => . body})
     (values title body)))

  ; render-blog-page: blog request -> html-response
  ; Produces an html-response page of the content of the
  ; blog.
  (define (render-blog-page a-blog request)
    (local [(define (response-generator make-url)
              `(html (head (title "My Blog"))
                     (body
                      (h1 "My Blog")
                      ,(render-posts a-blog make-url)
                      (form ([action
                              ,(make-url insert-post-handler)])
                            ,@(formlet-display new-post-formlet)
                            (input ([type "submit"]))))))

            (define (insert-post-handler request)
              (define-values (title body)
                (formlet-process new-post-formlet request))
              (blog-insert-post! a-blog title body)
              (render-blog-page a-blog (redirect/get)))]

      (send/suspend/dispatch response-generator)))

  ; new-comment-formlet : formlet string
  ; A formlet for requesting a comment
  (define new-comment-formlet
    input-string)

  ; render-post-detail-page: post request -> html-response
  ; Consumes a post and produces a detail page of the post.
  ; The user will be able to either insert new comments
  ; or go back to render-blog-page.
  (define (render-post-detail-page a-blog a-post request)
    (local [(define (response-generator make-url)
              `(html (head (title "Post Details"))
                     (body
                      (h1 "Post Details")
                      (h2 ,(post-title a-post))
                      (p ,(post-body a-post))
                      ,(render-as-itemized-list
                        (post-comments a-post))
                      (form ([action
                              ,(make-url insert-comment-handler)])
                            ,@(formlet-display new-comment-formlet)
                            (input ([type "submit"])))
                      (a ([href ,(make-url back-handler)])
                         "Back to the blog"))))

            (define (insert-comment-handler request)
              (render-confirm-add-comment-page
               a-blog
               (formlet-process new-comment-formlet request)
               a-post
               request))

            (define (back-handler request)
              (render-blog-page a-blog request))]

      (send/suspend/dispatch response-generator)))

  ; render-confirm-add-comment-page :
  ; blog comment post request -> html-response
  ; Consumes a comment that we intend to add to a post, as well
  ; as the request. If the user follows through, adds a comment
  ; and goes back to the display page. Otherwise, goes back to
  ; the detail page of the post.
  (define (render-confirm-add-comment-page a-blog a-comment
                                           a-post request)
    (local [(define (response-generator make-url)
              `(html (head (title "Add a Comment"))
                     (body
                      (h1 "Add a Comment")
                      "The comment: " (div (p ,a-comment))
                      "will be added to "
                      (div ,(post-title a-post))

                      (p (a ([href ,(make-url yes-handler)])
                            "Yes, add the comment."))
                      (p (a ([href ,(make-url cancel-handler)])
                            "No, I changed my mind!")))))

            (define (yes-handler request)
              (post-insert-comment! a-blog a-post a-comment)
              (render-post-detail-page a-blog a-post (redirect/get)))

            (define (cancel-handler request)
              (render-post-detail-page a-blog a-post request))]

      (send/suspend/dispatch response-generator)))

  ; render-post: post (handler -> string) -> html-response
  ; Consumes a post, produces an html-response fragment of the post.
  ; The fragment contains a link to show a detailed view of the post.
  (define (render-post a-blog a-post make-url)
    (local [(define (view-post-handler request)
              (render-post-detail-page a-blog a-post request))]
      `(div ([class "post"])
            (a ([href ,(make-url view-post-handler)])
               ,(post-title a-post))
            (p ,(post-body a-post))
            (div ,(number->string (length (post-comments a-post)))
                 " comment(s)"))))

  ; render-posts: blog (handler -> string) -> html-response
  ; Consumes a make-url, produces an html-response fragment
  ; of all its posts.
  (define (render-posts a-blog make-url)
    (local [(define (render-post/make-url a-post)
              (render-post a-blog a-post make-url))]
      `(div ([class "posts"])
            ,@(map render-post/make-url (blog-posts a-blog)))))

  ; render-as-itemized-list: (listof html-response) -> html-response
  ; Consumes a list of items, and produces a rendering as
  ; an unorderered list.
  (define (render-as-itemized-list fragments)
    `(ul ,@(map render-as-item fragments)))

  ; render-as-item: html-response -> html-response
  ; Consumes an html-response, and produces a rendering
  ; as a list item.
  (define (render-as-item a-fragment)
    `(li ,a-fragment))