Add some basic explanations for A, AAAA, NS, TXT, CNAME, MX records.

src/App/Page/Zone.purs

@@ -2,12 +2,14 @@
 -- |
 -- | This interface enables to:
 -- |   - display all resource records of a zone (SOA, NS, A, AAAA, CNAME, TXT, MX, SRV)
--- |   - provide dedicated interfaces for SPF and DKIM (TODO: DMARC)
+-- |   - provide dedicated interfaces for SPF, DKIM and DMARC
 -- |   - add, modify, remove resource records
 -- |
 -- | **WIP**: Display relevant information for each record type in the (add/mod) modal.
 -- | This includes explaining use cases and displaying an appropriate interface for the task at hand.
 -- |
+-- | TODO: CAA records.
+-- |
 -- | TODO: display errors not only for a record but for the whole zone.
 -- | A DNS zone is bound by a set of rules, the whole zone must be consistent.
 -- | For example, a CNAME `target` has to point to the `name` of an existing record.
@@ -294,7 +296,7 @@ default_domain :: String
 default_domain = "netlib.re"
 
 default_rr_A :: ResourceRecord
-default_rr_A = emptyRR { rrtype = "A", name = "www", target = "192.0.2.1" }
+default_rr_A = emptyRR { rrtype = "A", name = "server1", target = "192.0.2.1" }
 
 default_empty_rr :: ResourceRecord
 default_empty_rr = default_rr_A
@@ -387,11 +389,11 @@ render state
     render_current_rr_modal :: forall w. HH.HTML w Action
     render_current_rr_modal =
       case state._currentRR.rrtype of
-      "A"     -> template modal_content_simple (foot_content A)
+      "A"     -> template (modal_content_simple A)     (foot_content A)
-      "AAAA"  -> template modal_content_simple (foot_content AAAA)
+      "AAAA"  -> template (modal_content_simple AAAA)  (foot_content AAAA)
-      "TXT"   -> template modal_content_simple (foot_content TXT)
+      "TXT"   -> template (modal_content_simple TXT)   (foot_content TXT)
-      "CNAME" -> template modal_content_simple (foot_content CNAME)
+      "CNAME" -> template (modal_content_simple CNAME) (foot_content CNAME)
-      "NS"    -> template modal_content_simple (foot_content NS)
+      "NS"    -> template (modal_content_simple NS)    (foot_content NS)
       "MX"    -> template modal_content_mx     (foot_content MX)
       "SRV"   -> template modal_content_srv    (foot_content SRV)
       "SPF"   -> template modal_content_spf    (foot_content SPF)
@@ -404,9 +406,10 @@ render state
         render_errors = if A.length state._currentRR_errors > 0
                         then HH.div_ $ [ Bulma.h3 "Errors: " ] <> map error_to_paragraph state._currentRR_errors
                         else HH.div_ [ ]
-        modal_content_simple :: Array (HH.HTML w Action)
+        modal_content_simple :: AcceptedRRTypes -> Array (HH.HTML w Action)
-        modal_content_simple =
+        modal_content_simple x =
           [ render_errors
+          , render_introduction_text x
           , Bulma.input_with_side_text ("domain" <> state._currentRR.rrtype) "Name" "www"
               (updateForm Field_Domain)
               state._currentRR.name
@@ -428,9 +431,19 @@ render state
                         ]
                    else []
                  _             -> []
+
+        render_introduction_text :: AcceptedRRTypes -> HH.HTML w Action
+        render_introduction_text = case _ of
+            A     -> Bulma.div_content [] [Bulma.explanation Explanations.a_introduction]
+            AAAA  -> Bulma.div_content [] [Bulma.explanation Explanations.aaaa_introduction]
+            TXT   -> Bulma.div_content [] [Bulma.explanation Explanations.txt_introduction]
+            CNAME -> Bulma.div_content [] [Bulma.explanation Explanations.cname_introduction]
+            NS    -> Bulma.div_content [] [Bulma.explanation Explanations.ns_introduction]
+            _     -> HH.p_ []
         modal_content_mx :: Array (HH.HTML w Action)
         modal_content_mx =
           [ render_errors
+          , Bulma.div_content [] [Bulma.explanation Explanations.mx_introduction]
           , Bulma.input_with_side_text "domainMX" "Name" "www"
               (updateForm Field_Domain)
               state._currentRR.name
@@ -665,11 +678,11 @@ handleAction = case _ of
   CreateNewRRModal t -> do
     state <- H.get
     H.modify_ _ { rr_modal = NewRRModal t }
-    let default_rr_AAAA  = emptyRR { rrtype = "AAAA", name = "www", target = "2001:db8::1" }
+    let default_rr_AAAA  = emptyRR { rrtype = "AAAA", name = "server1", target = "2001:db8::1" }
         default_rr_TXT   = emptyRR { rrtype = "TXT", name = "txt", target = "some text" }
-        default_rr_CNAME = emptyRR { rrtype = "CNAME", name = "blog", target = "www" }
+        default_rr_CNAME = emptyRR { rrtype = "CNAME", name = "www", target = "server1" }
         default_rr_NS    = emptyRR { rrtype = "NS", name = (state._domain <> "."), target = "ns0.example.com." }
-        default_rr_MX    = emptyRR { rrtype = "MX", name = "mail", target = "www", priority = Just 10 }
+        default_rr_MX    = emptyRR { rrtype = "MX", name = "mail", target = "server1", priority = Just 10 }
         default_rr_SRV   = emptyRR { rrtype = "SRV", name = "voip", target = "server1"
                                    , port = Just 5061, weight = Just 100, priority = Just 10, protocol = Just "tcp" }
         default_mechanisms = maybe [] (\x -> [x]) $ to_mechanism "pass" "mx" ""

src/App/Text/Explanations.purs

@@ -155,6 +155,110 @@ basics = HH.div_
   , Bulma.p "Check out the \"Tokens? 🤨\" tab."
   ]
 
+a_introduction :: forall w i. Array (HH.HTML w i)
+a_introduction =
+  [ Bulma.p """
+    The A record enables to bind an IPv4 address to a domain.
+    """
+  , HH.p []
+    [ HH.text "🚨 "
+    , HH.u_ [HH.text "Advice for beginners"]
+    , HH.text ":"
+    , HH.text """
+      the "Name" field is for the name of the record, which should be the name of the server owning this IP address, such as "server1".
+      The "Target" field is for the IP address.
+      The default TTL should be fine.
+      """
+    ]
+  ]
+
+aaaa_introduction :: forall w i. Array (HH.HTML w i)
+aaaa_introduction =
+  [ Bulma.p """
+    The AAAA record enables to bind an IPv6 address to a domain.
+    """
+  , HH.p []
+    [ HH.text "🚨 "
+    , HH.u_ [HH.text "Advice for beginners"]
+    , HH.text ":"
+    , HH.text """
+      the "Name" field is for the name of the record, which should be the name of the server owning this IP address, such as "server1".
+      The "Target" field is for the IP address.
+      The default TTL should be fine.
+      """
+    ]
+  ]
+
+cname_introduction :: forall w i. Array (HH.HTML w i)
+cname_introduction =
+  [ Bulma.p """
+    The CNAME record enables to provide alternative names to records.
+    """
+  , HH.p []
+    [ HH.text "🚨 "
+    , HH.u_ [HH.text "Advice for beginners"]
+    , HH.text ":"
+    , HH.text """
+      this resource record helps keeping your zone clean.
+      Let's say you have a server named "server1", you can register an A record for that server (since the server actually has an IP address).
+      Then, your hosted services will be registered in your zone as CNAMEs: "www", "blog" and "voip" will point to "server1", the actual server hosting these services.
+      """
+    ]
+  ]
+
+mx_introduction :: forall w i. Array (HH.HTML w i)
+mx_introduction =
+  [ Bulma.p """
+    The MX record enables to add a mail server to your zone.
+    """
+  , HH.p []
+    [ HH.text "🚨 "
+    , HH.u_ [HH.text "Advice for beginners"]
+    , HH.text ": handling a mail server is both complex and difficult."
+    , HH.text """
+        The tab "The basics 🧠" explains some parts of hosting a mail server, but keep in mind that this is time consuming to get it together.
+        This page talks about the DNS aspect of it, but doesn't cover all you need to know to actually host a mail server, by a long shot.
+      """
+    ]
+  , Bulma.p """
+    Anyway, the MX record itself is simple to understand.
+    Let's say you have a server named "server1" with your mail service.
+    The MX record can be named "mail" and it will target "server1".
+    Of course, "server1" needs a record for its IP address (A or AAAA).
+    """
+  , Bulma.p """
+    The priority field is important only in case you have multiple mail servers; keep the default value.
+    """
+  ]
+
+txt_introduction :: forall w i. Array (HH.HTML w i)
+txt_introduction =
+  [ Bulma.p """
+    The TXT record enables to declare a small text.
+    """
+  , HH.p []
+    [ HH.text "🚨 "
+    , HH.u_ [HH.text "Advice for beginners"]
+    , HH.text ":"
+    , HH.text """
+        do not use this record directly.
+        TXT records are used in several places, for example for mail security through SPF, DKIM and DMARC records.
+      """
+    ]
+  , Bulma.notification_danger' """
+      All of these specific records have a dedicated user interface on this website;
+      use them instead of writing these records by yourself.
+    """
+  ]
+
+ns_introduction :: forall w i. Array (HH.HTML w i)
+ns_introduction =
+  [ Bulma.p """
+    The NS record enables to declare a new Name Server, meaning a new server that would serve this zone.
+    """
+  , Bulma.notification_danger' "🚨 Advice for beginners: do not use this resource record."
+  ]
+
 dkim_introduction :: forall w i. Array (HH.HTML w i)
 dkim_introduction =
   [ Bulma.p """