#lang racket/base

(require net/url
         net/uri-codec
         racket/file
         racket/list
         racket/string
         (prefix-in cookie: net/cookies/server)
         web-server/dispatch
         web-server/dispatchers/dispatch
         web-server/http
         web-server/servlet-env
         "private/auth.rkt"
         "private/config.rkt"
         "private/http-util.rkt"
         "private/setup.rkt"
         "private/storage.rkt"
         "translate.rkt")

(provide start-wiki-server)

(define (user->jsexpr user)
  (hash 'id (wiki-user-id user)
        'username (wiki-user-username user)
        'displayName (wiki-user-display-name user)
        'role (symbol->string (wiki-user-role user))
        'enabled (wiki-user-enabled? user)))

(define (session->jsexpr session)
  (if session
      (hash 'authenticated #t
            'user (user->jsexpr (wiki-session-user session))
            'csrfToken (wiki-session-csrf-token session))
      (hash 'authenticated #f)))

(define (require-role config req role proc)
  (define session (session-from-request config req))
  (cond
    ((not session) (json-error 401 "Authentication required"))
    ((not (role-at-least? (wiki-session-user session) role))
     (json-error 403 "Insufficient permissions"))
    (else (proc session))))

(define (require-write-role config req role proc)
  (require-role
   config req role
   (λ (session)
     (define csrf (request-header/string req "X-CSRF-Token"))
     (if (csrf-valid? session csrf)
         (proc session)
         (json-error 403 "Invalid CSRF token")))))

(define (session-cookie-header config session)
  (define cookie
    (cookie:make-cookie "racket-wiki-session"
                        (wiki-session-token session)
                        #:path "/"
                        #:max-age (wiki-config-session-seconds config)
                        #:http-only? #t
                        #:secure? (wiki-config-secure-cookie? config)
                        #:extension "SameSite=Strict"))
  (make-header #"Set-Cookie"
               (cookie:cookie->set-cookie-header cookie)))

(define (login-handler config req)
  (with-handlers ((exn:fail? (λ (e) (json-error 400 (exn-message e)))))
    (define body (request-json req))
    (define username (hash-ref body 'username ""))
    (define password (hash-ref body 'password ""))
    (define user (authenticate-user config username password))
    (cond
      ((not user) (json-error 401 "Invalid username or password"))
      (else
       (define session (create-session! config user))
       (json-response
        (session->jsexpr session)
        #:headers (list (session-cookie-header config session)))))))

(define login-style
  #<<CSS
html { box-sizing: border-box; font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif; color: #172033; background: #f4f6f8; }
*, *::before, *::after { box-sizing: inherit; }
body { margin: 0; min-height: 100vh; display: grid; place-items: center; padding: 32px; }
.login { width: min(440px, 100%); background: white; border: 1px solid #d7dde5; border-radius: 14px; padding: 34px; box-shadow: 0 12px 40px rgba(22, 32, 51, 0.08); }
h1 { margin: 0 0 24px; font-size: 2rem; }
label { display: block; margin: 16px 0; font-weight: 600; }
input { display: block; width: 100%; margin-top: 6px; padding: 10px 12px; font: inherit; border: 1px solid #aeb7c4; border-radius: 6px; }
button { margin-top: 2px; padding: 9px 14px; font: inherit; cursor: pointer; }
.error { margin: 0 0 18px; padding: 12px 14px; background: #fff1f1; border: 1px solid #e8b7b7; border-radius: 6px; color: #8b1f1f; }
CSS
  )

(define (request-form req)
  (define body (request-post-data/raw req))
  (if body
      (form-urlencoded->alist (bytes->string/utf-8 body))
      '()))

(define (form-value form key [default ""])
  (define found (assoc key form))
  (if (and found (cdr found))
      (cdr found)
      default))

(define (login-page config [message #f] [username ""])
  `(html
    (head
     (meta ((charset "utf-8")))
     (meta ((name "viewport") (content "width=device-width, initial-scale=1")))
     (title ,(string-append (tr config 'sign-in) " - " (wiki-config-site-title config)))
     (style ,login-style))
    (body
     (main ((class "login"))
       (h1 ,(tr config 'sign-in))
       ,@(if message
             `((div ((class "error")) ,message))
             '())
       (form ((method "post") (action "/login"))
         (label
          ,(tr config 'username)
          (input ((name "username")
                  (value ,username)
                  (autocomplete "username")
                  (required "required")
                  (autofocus "autofocus"))))
         (label
          ,(tr config 'password)
          (input ((name "password")
                  (type "password")
                  (autocomplete "current-password")
                  (required "required"))))
         (button ((type "submit")) ,(tr config 'sign-in)))))))

(define (login-page-response config [message #f] [username ""])
  (html-response
   (login-page config message username)
   #:code (if message 401 200)
   #:headers (list (make-header #"Cache-Control" #"no-store"))))

(define (browser-login-handler config req)
  (define session (session-from-request config req))
  (cond
    (session
     (redirect-response "/"))
    ((string-ci=? (bytes->string/latin-1 (request-method req)) "POST")
     (define form (request-form req))
     (define username (string-trim (form-value form 'username)))
     (define password (form-value form 'password))
     (define user (authenticate-user config username password))
     (cond
       ((not user)
        (login-page-response config "Invalid username or password" username))
       (else
        (define new-session (create-session! config user))
        (redirect-response
         "/"
         #:headers (list (session-cookie-header config new-session))))))
    (else
     (login-page-response config))))

(define (logout-handler config req)
  (require-write-role
   config req 'reader
   (λ (session)
     (delete-session! config (wiki-session-token session))
     (json-response
      (hash 'ok #t)
      #:headers
      (list (make-header #"Set-Cookie"
                         (cookie:clear-cookie-header "racket-wiki-session" #:path "/")))))))

(define (page-list-handler config req)
  (require-role
   config req 'reader
   (λ (_session)
     (json-response (hash 'pages (list-pages config))))))

(define (request-query-value req key [default ""])
  (define found (assoc key (url-query (request-uri req))))
  (if found (cdr found) default))

(define (search-handler config req)
  (require-role
   config req 'reader
   (λ (_session)
     (define query-text (request-query-value req 'q))
     (json-response (hash 'results (search-pages config query-text))))))

(define (todo-list-handler config req)
  (require-role
   config req 'reader
   (λ (_session)
     (json-response (hash 'items (list-todos config))))))

(define (translations-handler config req)
  (require-role
   config req 'reader
   (λ (_session)
     (json-response
      (hash 'language (current-language config)
            'page (translation-page-slug (current-language config))
            'translations (translations-for config))))))

(define (page-get-handler config req slug)
  (require-role
   config req 'reader
   (λ (_session)
     (define page (and (valid-slug? slug) (read-page config slug)))
     (if page
         (json-response page)
         (json-error 404 "Page not found")))))

(define (request-tags body)
  (define value (hash-ref body 'tags '()))
  (if (and (list? value)
           (for/and ((tag (in-list value)))
             (string? tag)))
      value
      (raise-argument-error 'request-tags "list of strings" value)))

(define (page-create-handler config req)
  (require-write-role
   config req 'editor
   (λ (session)
     (with-handlers ((exn:fail? (λ (e) (json-error 400 (exn-message e)))))
       (define body (request-json req))
       (define requested-slug (hash-ref body 'slug #f))
       (define title (hash-ref body 'title ""))
       (define markdown (hash-ref body 'markdown ""))
       (define tags (request-tags body))
       (define summary (hash-ref body 'summary "Created page"))
       (define slug
         (if requested-slug
             requested-slug
             (title->slug title)))
       (cond
         ((string=? (string-trim title) "")
          (json-error 400 "Title is required"))
         ((string=? slug "")
          (json-error 400 "The title cannot be converted to a page slug"))
         ((not (valid-slug? slug))
          (json-error 400 "Invalid page address"))
         ((read-page config slug)
          (json-error 409 "A page with this address already exists"))
         (else
          (json-response
           (create-page! config
                         slug
                         title
                         markdown
                         (wiki-user-username (wiki-session-user session))
                         summary
                         tags)
           #:code 201)))))))

(define (page-update-handler config req slug)
  (require-write-role
   config req 'editor
   (λ (session)
     (with-handlers ((exn:fail?
                      (λ (e)
                        (if (string=? (exn-message e) "update-page!: version-conflict")
                            (json-error 409 "Page changed since it was opened")
                            (json-error 400 (exn-message e))))))
       (define body (request-json req))
       (define title (hash-ref body 'title ""))
       (define markdown (hash-ref body 'markdown ""))
       (define tags (request-tags body))
       (define base-version (hash-ref body 'baseVersion ""))
       (define summary (hash-ref body 'summary "Edited page"))
       (json-response
        (update-page! config
                      slug
                      title
                      markdown
                      (wiki-user-username (wiki-session-user session))
                      base-version
                      summary
                      tags))))))

(define (page-delete-handler config req slug)
  (require-write-role
   config req 'editor
   (λ (session)
     (with-handlers ((exn:fail? (λ (e) (json-error 400 (exn-message e)))))
       (archive-page! config
                      slug
                      (wiki-user-username (wiki-session-user session)))
       (json-response (hash 'ok #t))))))

(define (history-handler config req slug)
  (require-role
   config req 'reader
   (λ (_session)
     (with-handlers ((exn:fail? (λ (e) (json-error 404 (exn-message e)))))
       (json-response (hash 'versions (page-history config slug)))))))

(define (version-handler config req slug version)
  (require-role
   config req 'reader
   (λ (_session)
     (define result (read-version config slug version))
     (if result
         (json-response result)
         (json-error 404 "Version not found")))))

(define (upload-handler config req slug)
  (require-write-role
   config req 'editor
   (λ (session)
     (define name (or (request-header/string req "X-File-Name") "upload.bin"))
     (define content (or (request-post-data/raw req) #""))
     (cond
       ((> (bytes-length content) (* 50 1024 1024))
        (json-error 413 "Upload exceeds 50 MiB"))
       (else
        (with-handlers ((exn:fail? (λ (e) (json-error 400 (exn-message e)))))
          (json-response (save-upload! config
                                      slug
                                      name
                                      content
                                      (wiki-user-username (wiki-session-user session)))
                         #:code 201)))))))

(define (inline-image-mime? mime)
  (if (member mime
              '(#"image/png"
                #"image/jpeg"
                #"image/gif"
                #"image/webp"))
      #t
      #f))

(define (upload-file-response attachment)
  (define mime (string->bytes/utf-8 (hash-ref attachment 'mimeType)))
  (define stored-name (hash-ref attachment 'storedName))
  (define original-name (hash-ref attachment 'originalName))
  (define disposition
    (if (inline-image-mime? mime)
        #"inline"
        (string->bytes/utf-8
         (format "attachment; filename=\"~a\"" original-name))))
  (bytes-response
   (hash-ref attachment 'content)
   mime
   #:headers
   (list (make-header #"Content-Disposition" disposition))))

(define (upload-get-handler config req slug stored-name)
  (require-role
   config req 'reader
   (λ (_session)
     (define attachment (uploaded-file config slug stored-name))
     (if attachment
         (upload-file-response attachment)
         (json-error 404 "File not found")))))

(define (admin-users-handler config req)
  (require-role
   config req 'admin
   (λ (_session)
     (json-response (hash 'users (map user->jsexpr (list-users config)))))))

(define (admin-create-user-handler config req)
  (require-write-role
   config req 'admin
   (λ (_session)
     (with-handlers ((exn:fail? (λ (e) (json-error 400 (exn-message e)))))
       (define body (request-json req))
       (define username (hash-ref body 'username ""))
       (define display-name (hash-ref body 'displayName username))
       (define password (hash-ref body 'password ""))
       (define role (string->symbol (hash-ref body 'role "reader")))
       (define status (if (hash-ref body 'enabled #t) 'enabled 'disabled))
       (unless (member role '(reader editor admin))
         (error 'admin-create-user-handler "Invalid role"))
       (when (or (string=? username "") (string=? password ""))
         (error 'admin-create-user-handler "Username and password are required"))
       (create-user! config username display-name password role status)
       (json-response (hash 'ok #t) #:code 201)))))

(define (admin-update-user-handler config req id)
  (require-write-role
   config req 'admin
   (λ (_session)
     (with-handlers ((exn:fail? (λ (e) (json-error 400 (exn-message e)))))
       (define body (request-json req))
       (define display-name (hash-ref body 'displayName ""))
       (define role (string->symbol (hash-ref body 'role "reader")))
       (define status (if (hash-ref body 'enabled #t) 'enabled 'disabled))
       (define password (hash-ref body 'password #f))
       (unless (member role '(reader editor admin))
         (error 'admin-update-user-handler "Invalid role"))
       (update-user! config id display-name role status password)
       (json-response (hash 'ok #t))))))

(define (admin-delete-user-handler config req id)
  (require-write-role
   config req 'admin
   (λ (session)
     (if (= id (wiki-user-id (wiki-session-user session)))
         (json-error 400 "You cannot delete your own account")
         (begin
           (delete-user! config id)
           (json-response (hash 'ok #t)))))))

(define (request-path-string req)
  (define segments
    (for/list ([segment (in-list (url-path (request-uri req)))])
      (path/param-path segment)))
  (string-append "/" (string-join segments "/")))

(define (index-response)
  (bytes-response
   (file->bytes (build-path static-directory "index.html"))
   #"text/html; charset=utf-8"
   #:headers (list (make-header #"Cache-Control" #"no-cache"))))

(define (static-request-path? path)
  (or (regexp-match? #px"^/(vendor|css|js)/" path)
      (string=? path "/favicon.ico")))

(define (application-api-path? path)
  (or (regexp-match? #px"^/api(/|$)" path)
      (regexp-match? #px"^/uploads(/|$)" path)))

(define (request-page-slug path)
  (define match (regexp-match #px"^/([^/]+)/?$" path))
  (if match
      (list-ref match 1)
      #f))

(define (page-location slug)
  (string-append "/#/" (uri-path-segment-unreserved-encode slug)))

(define (not-found-response config)
  (html-response
   `(html
     (head
      (meta ((charset "utf-8")))
      (meta ((name "viewport") (content "width=device-width, initial-scale=1")))
      (title ,(string-append "Not found - " (wiki-config-site-title config))))
     (body
      (h1 "Page not found")))
   #:code 404
   #:headers (list (make-header #"Cache-Control" #"no-store"))))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; goal   : Start the HTTP server for the wiki.
; pre    : config is initialized and its static and data paths are available.
; post   : The server is listening until the servlet environment stops. When
;          initial setup is incomplete, normal application requests redirect
;          to /setup.
; result : The result returned by serve/servlet.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(define (start-wiki-server config)
  (define-values (application-dispatch _url)
    (dispatch-rules
     [("api" "session") #:method "get"
      (λ (req)
        (json-response
         (session->jsexpr (session-from-request config req))))]
     [("api" "login") #:method "post"
      (λ (req) (login-handler config req))]
     [("api" "logout") #:method "post"
      (λ (req) (logout-handler config req))]
     [("api" "ping") #:method "get"
      (λ (_req) (json-response (hash 'ok #t 'time (current-seconds))))]
     [("api" "translations") #:method "get"
      (λ (req) (translations-handler config req))]
     [("api" "todos") #:method "get"
      (λ (req) (todo-list-handler config req))]
     [("api" "search") #:method "get"
      (λ (req) (search-handler config req))]
     [("api" "pages") #:method "get"
      (λ (req) (page-list-handler config req))]
     [("api" "pages") #:method "post"
      (λ (req) (page-create-handler config req))]
     [("api" "pages" (string-arg)) #:method "get"
      (λ (req slug) (page-get-handler config req slug))]
     [("api" "pages" (string-arg)) #:method "put"
      (λ (req slug) (page-update-handler config req slug))]
     [("api" "pages" (string-arg)) #:method "delete"
      (λ (req slug) (page-delete-handler config req slug))]
     [("api" "pages" (string-arg) "history") #:method "get"
      (λ (req slug) (history-handler config req slug))]
     [("api" "pages" (string-arg) "versions" (string-arg)) #:method "get"
      (λ (req slug version) (version-handler config req slug version))]
     [("api" "pages" (string-arg) "upload") #:method "post"
      (λ (req slug) (upload-handler config req slug))]
     [("uploads" (string-arg) (string-arg)) #:method "get"
      (λ (req slug stored-name) (upload-get-handler config req slug stored-name))]
     [("api" "admin" "users") #:method "get"
      (λ (req) (admin-users-handler config req))]
     [("api" "admin" "users") #:method "post"
      (λ (req) (admin-create-user-handler config req))]
     [("api" "admin" "users" (integer-arg)) #:method "put"
      (λ (req id) (admin-update-user-handler config req id))]
     [("api" "admin" "users" (integer-arg)) #:method "delete"
      (λ (req id) (admin-delete-user-handler config req id))]
     [else (λ (_req) (json-error 404 "API endpoint not found"))]))

  (define setup-ready? (box (setup-complete? config)))

  (define (dispatch req)
    (define path (request-path-string req))
    (cond
      ((regexp-match? #px"^/setup/?$" path)
       (define response (setup-handler config req))
       (when (setup-complete? config)
         (set-box! setup-ready? #t))
       response)
      ((not (unbox setup-ready?))
       (redirect-response "/setup"))
      ((regexp-match? #px"^/login/?$" path)
       (browser-login-handler config req))
      ((static-request-path? path)
       (next-dispatcher))
      ((application-api-path? path)
       (application-dispatch req))
      ((or (string=? path "/")
           (string=? path "/index.html"))
       (if (session-from-request config req)
           (index-response)
           (redirect-response "/login")))
      (else
       (define session (session-from-request config req))
       (define slug (request-page-slug path))
       (cond
         ((not session)
          (redirect-response "/login"))
         ((and slug (valid-slug? slug))
          (let ((page (read-page config slug)))
            (cond
              (page
               (redirect-response (page-location slug)))
              ((role-at-least? (wiki-session-user session) 'editor)
               (redirect-response (page-location slug)))
              (else
               (not-found-response config)))))
         (else
          (not-found-response config))))))

  (displayln
   (format "~a listening on http://~a:~a/"
           (wiki-config-site-title config)
           (or (wiki-config-listen-ip config) "0.0.0.0")
           (wiki-config-port config)))

  (when (not (unbox setup-ready?))
    (displayln "Initial setup is required. Open /setup in a browser."))

  (serve/servlet dispatch
                 #:launch-browser? #f
                 #:quit? #f
                 #:banner? #f
                 #:listen-ip (wiki-config-listen-ip config)
                 #:port (wiki-config-port config)
                 #:servlet-regexp #rx""
                 #:extra-files-paths (list (data-static-directory config)
                                           static-directory)))