From c0bc0da02a1d683fdd0918bbd26cd4ee9be0b523 Mon Sep 17 00:00:00 2001
From: Sridhar Ratnakumar <srid@srid.ca>
Date: Tue, 27 Apr 2021 12:59:19 -0400
Subject: [PATCH] Add basic example

---
 .ghcid                                        |  2 +-
 CHANGELOG.md                                  |  3 +-
 ema.cabal                                     |  3 +-
 src/Ema/Example/Ex02_Basic.hs                 | 60 +++++++++++++++++++
 .../Example/{Ex02_Clock.hs => Ex03_Clock.hs}  |  2 +-
 src/Ema/Server.hs                             |  4 +-
 6 files changed, 68 insertions(+), 6 deletions(-)
 create mode 100644 src/Ema/Example/Ex02_Basic.hs
 rename src/Ema/Example/{Ex02_Clock.hs => Ex03_Clock.hs} (98%)

diff --git a/.ghcid b/.ghcid
index 848c681..028d12a 100644
--- a/.ghcid
+++ b/.ghcid
@@ -1 +1 @@
---warnings -T Ema.Example.Ex02_Clock.main 
+--warnings -T Ema.Example.Ex03_Clock.main 
diff --git a/CHANGELOG.md b/CHANGELOG.md
index ab773f2..2e77e27 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,9 +2,10 @@
 
 ## Unreleased
 
-- Helpers.Tailwind: add overflow-y-scroll to body
 - Remove Ex03_Documentation.hs (moved to separate repo, `ema-docs`)
 - Add `Ord` instance to `Slug`
+- Helpers.Tailwind: add overflow-y-scroll to body
+- Add Ex03_Basic.hs example
 
 ## 0.1.0.0 -- 2021-04-26
 
diff --git a/ema.cabal b/ema.cabal
index dd981f6..2c5cd0f 100644
--- a/ema.cabal
+++ b/ema.cabal
@@ -111,7 +111,8 @@ library
   if flag(with-examples)
     exposed-modules:
       Ema.Example.Ex01_HelloWorld
-      Ema.Example.Ex02_Clock
+      Ema.Example.Ex02_Basic
+      Ema.Example.Ex03_Clock
 
   hs-source-dirs:     src
   default-language:   Haskell2010
diff --git a/src/Ema/Example/Ex02_Basic.hs b/src/Ema/Example/Ex02_Basic.hs
new file mode 100644
index 0000000..85c7fad
--- /dev/null
+++ b/src/Ema/Example/Ex02_Basic.hs
@@ -0,0 +1,60 @@
+{-# LANGUAGE TypeApplications #-}
+{-# OPTIONS_GHC -fno-warn-orphans #-}
+
+-- | A very simple site with routes, but based on dynamically changing values
+--
+-- The current time is computed in the server every second, and the resultant
+-- generated HTML is automatically updated on the browser. This is only a demo;
+-- usually we render HTML based on files on disk or something accessible outside
+-- of the browser. More advanced examples will demonstrate that.
+module Ema.Example.Ex02_Basic where
+
+import Control.Concurrent (threadDelay)
+import qualified Data.LVar as LVar
+import Ema (Ema (..), routeUrl, runEma)
+import qualified Ema.CLI
+import qualified Ema.Helper.Tailwind as Tailwind
+import Text.Blaze.Html5 ((!))
+import qualified Text.Blaze.Html5 as H
+import qualified Text.Blaze.Html5.Attributes as A
+
+data Route
+  = Index
+  | About
+  deriving (Show, Enum, Bounded)
+
+instance Ema () Route where
+  encodeRoute = \case
+    Index -> mempty
+    About -> one "about"
+  decodeRoute = \case
+    [] -> Just Index
+    ["about"] -> Just About
+    _ -> Nothing
+  staticRoutes _ =
+    [minBound .. maxBound]
+
+main :: IO ()
+main = do
+  runEma render $ \model ->
+    forever $ do
+      LVar.set model ()
+      liftIO $ threadDelay maxBound
+
+render :: Ema.CLI.Action -> () -> Route -> LByteString
+render emaAction () r =
+  Tailwind.layout emaAction (H.title "Basic site") $
+    H.div ! A.class_ "container mx-auto" $ do
+      H.div ! A.class_ "mt-8 p-2 text-center" $ do
+        case r of
+          Index -> do
+            "You are on the index page. "
+            routeElem About "Go to About"
+          About -> do
+            "You are on the about page. "
+            routeElem Index "Go to Index"
+  where
+    routeElem r' w =
+      H.a ! A.class_ "text-red-500 hover:underline" ! routeHref r' $ w
+    routeHref r' =
+      A.href (fromString . toString $ routeUrl r')
diff --git a/src/Ema/Example/Ex02_Clock.hs b/src/Ema/Example/Ex03_Clock.hs
similarity index 98%
rename from src/Ema/Example/Ex02_Clock.hs
rename to src/Ema/Example/Ex03_Clock.hs
index aa21864..bbba9b5 100644
--- a/src/Ema/Example/Ex02_Clock.hs
+++ b/src/Ema/Example/Ex03_Clock.hs
@@ -7,7 +7,7 @@
 -- generated HTML is automatically updated on the browser. This is only a demo;
 -- usually we render HTML based on files on disk or something accessible outside
 -- of the browser. More advanced examples will demonstrate that.
-module Ema.Example.Ex02_Clock where
+module Ema.Example.Ex03_Clock where
 
 import Control.Concurrent (threadDelay)
 import qualified Data.LVar as LVar
diff --git a/src/Ema/Server.hs b/src/Ema/Server.hs
index 02d6094..8dd81eb 100644
--- a/src/Ema/Server.hs
+++ b/src/Ema/Server.hs
@@ -76,10 +76,10 @@ runServerWithWebSocketHotReload port model render = do
                   -- to switch to a new route.
                   liftIO $ do
                     race (LVar.listenNext model subId) (runLoggingT askClientForRoute logger) >>= \res -> flip runLoggingT logger $ case res of
-                      Left newHtml -> do
+                      Left newModel -> do
                         -- The page the user is currently viewing has changed. Send
                         -- the new HTML to them.
-                        sendRouteHtmlToClient watchingRoute newHtml
+                        sendRouteHtmlToClient watchingRoute newModel
                         lift loop
                       Right nextRoute -> do
                         -- The user clicked on a route link; send them the HTML for