46 files changed, 599 insertions, 850 deletions

diff --git a/Makefile b/Makefile
deleted file mode 100644
index 6c9a2b3..0000000
--- a/Makefile
+++ /dev/null
@@ -1,22 +0,0 @@
-export PATH := node_modules/.bin:$(PATH)
-
-build: public/main.js
-
-public/main.js: node_modules $(shell find src \( -type d -o \( -type f -a -regex ".*\.ml" \) \))
-	@echo "Building $@"
-	@bsb -make-world
-	@rollup --config rollup.config.js
-	@terser $@ --output $@ --compress --mangle
-
-node_modules: package.json
-	@bsb -init init
-	@mv init/node_modules .
-	@rm -rf init
-	@npm install
-	@touch -c node_modules
-
-clean:
-	@echo "Cleaning"
-	@rm -f public/main.js
-	@rm -rf node_modules lib
-	@find src -name '*.bs.js' -exec rm {} \;
diff --git a/README.md b/README.md
index f1d9c26..9f5b91f 100644
--- a/README.md
+++ b/README.md
@@ -1,29 +1,9 @@
-# Tabata timer
+# Getting started
 
-Available at [https://guyonvarch.gitlab.io/tabata-timer](https://guyonvarch.gitlab.io/tabata-timer).
+Run:
 
-## Gettings started
-
-Start the environment with:
-
-```bash
-./dev start
-```
-
-Later, stop the environment with:
-
-```bash
-./dev stop
+```sh
+nix-shell --run bin/watch.sh
 ```
 
-## Deploy
-
-```bash
-nix-shell --run ./deploy
-```
-
-## Bucklescript links
-
-- [Documentation](https://bucklescript.github.io/docs/en/interop-overview)
-- [Ocaml std API](https://caml.inria.fr/pub/docs/manual-ocaml-4.02/stdlib.html)
-- [Libraries](https://bucklescript.github.io/bucklescript/api/index.html)
+Then, open your browser at `http://localhost:8000`.
diff --git a/bin/watch.sh b/bin/watch.sh
new file mode 100755
index 0000000..86eeab7
--- /dev/null
+++ b/bin/watch.sh
@@ -0,0 +1,8 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+python -m http.server --directory public 8000 &
+
+trap "fuser -k 8000/tcp" EXIT
+
+tsc --target ES2017 --watch
diff --git a/bsconfig.json b/bsconfig.json
deleted file mode 100644
index db0c8d9..0000000
--- a/bsconfig.json
+++ /dev/null
@@ -1,22 +0,0 @@
-{
-  "name": "tabata-timer",
-  "version": "0.1.0",
-  "sources": {
-    "dir": "src",
-    "subdirs": true
-  },
-  "package-specs": {
-    "module": "es6",
-    "in-source": true
-  },
-  "suffix": ".bs.js",
-  "bs-dependencies": [],
-  "warnings": {
-    "number": "+A-42-40-4",
-    "error": "+A-40-4"
-  },
-  "bsc-flags": [
-    "-bs-super-errors"
-  ],
-  "refmt": 3
-}
diff --git a/deploy b/deploy
deleted file mode 100755
index 8ceaa8f..0000000
--- a/deploy
+++ /dev/null
@@ -1,12 +0,0 @@
-#!/usr/bin/env bash
-set -e
-
-# Build
-git branch -D pages || true
-git checkout -b pages
-make clean build
-git add --force public/main.js
-git commit -m "Deploy pages"
-git push --force origin pages
-git checkout master
-git branch -D pages
diff --git a/dev b/dev
deleted file mode 100755
index af2b51a..0000000
--- a/dev
+++ /dev/null
@@ -1,27 +0,0 @@
-#!/usr/bin/env bash
-cd "$(dirname $0)"
-CMD="$1"
-PROJECT="tabata-timer"
-
-if [ "$CMD" = "start" ]; then
-
-  nix-shell --run "make node_modules && tmuxinator local"
-
-elif [ "$CMD" = "stop" ]; then
-
-  nix-shell --run "tmux kill-session -t $PROJECT"
-
-elif [ "$CMD" = "watch-ocaml" ]; then
-
-	bsb -make-world -w
-
-elif [ "$CMD" = "watch-js" ]; then
-
-  node_modules/.bin/rollup --watch --config rollup.config.js
-
-else
-
-  echo "Usage: $0 start|stop|watch-ocaml|watch-js"
-  exit 1
-
-fi
diff --git a/package-lock.json b/package-lock.json
deleted file mode 100644
index f20e082..0000000
--- a/package-lock.json
+++ /dev/null
@@ -1,150 +0,0 @@
-{
-  "name": "tabata-timer",
-  "version": "0.1.0",
-  "lockfileVersion": 1,
-  "requires": true,
-  "dependencies": {
-    "@rollup/plugin-node-resolve": {
-      "version": "7.1.1",
-      "resolved": "https://registry.npmjs.org/@rollup/plugin-node-resolve/-/plugin-node-resolve-7.1.1.tgz",
-      "integrity": "sha512-14ddhD7TnemeHE97a4rLOhobfYvUVcaYuqTnL8Ti7Jxi9V9Jr5LY7Gko4HZ5k4h4vqQM0gBQt6tsp9xXW94WPA==",
-      "dev": true,
-      "requires": {
-        "@rollup/pluginutils": "^3.0.6",
-        "@types/resolve": "0.0.8",
-        "builtin-modules": "^3.1.0",
-        "is-module": "^1.0.0",
-        "resolve": "^1.14.2"
-      }
-    },
-    "@rollup/pluginutils": {
-      "version": "3.0.8",
-      "resolved": "https://registry.npmjs.org/@rollup/pluginutils/-/pluginutils-3.0.8.tgz",
-      "integrity": "sha512-rYGeAc4sxcZ+kPG/Tw4/fwJODC3IXHYDH4qusdN/b6aLw5LPUbzpecYbEJh4sVQGPFJxd2dBU4kc1H3oy9/bnw==",
-      "dev": true,
-      "requires": {
-        "estree-walker": "^1.0.1"
-      }
-    },
-    "@types/estree": {
-      "version": "0.0.42",
-      "resolved": "https://registry.npmjs.org/@types/estree/-/estree-0.0.42.tgz",
-      "integrity": "sha512-K1DPVvnBCPxzD+G51/cxVIoc2X8uUVl1zpJeE6iKcgHMj4+tbat5Xu4TjV7v2QSDbIeAfLi2hIk+u2+s0MlpUQ==",
-      "dev": true
-    },
-    "@types/node": {
-      "version": "13.7.1",
-      "resolved": "https://registry.npmjs.org/@types/node/-/node-13.7.1.tgz",
-      "integrity": "sha512-Zq8gcQGmn4txQEJeiXo/KiLpon8TzAl0kmKH4zdWctPj05nWwp1ClMdAVEloqrQKfaC48PNLdgN/aVaLqUrluA==",
-      "dev": true
-    },
-    "@types/resolve": {
-      "version": "0.0.8",
-      "resolved": "https://registry.npmjs.org/@types/resolve/-/resolve-0.0.8.tgz",
-      "integrity": "sha512-auApPaJf3NPfe18hSoJkp8EbZzer2ISk7o8mCC3M9he/a04+gbMF97NkpD2S8riMGvm4BMRI59/SZQSaLTKpsQ==",
-      "dev": true,
-      "requires": {
-        "@types/node": "*"
-      }
-    },
-    "acorn": {
-      "version": "7.1.0",
-      "resolved": "https://registry.npmjs.org/acorn/-/acorn-7.1.0.tgz",
-      "integrity": "sha512-kL5CuoXA/dgxlBbVrflsflzQ3PAas7RYZB52NOm/6839iVYJgKMJ3cQJD+t2i5+qFa8h3MDpEOJiS64E8JLnSQ==",
-      "dev": true
-    },
-    "bs-platform": {
-      "version": "7.0.1",
-      "dev": true
-    },
-    "bs-webapi": {
-      "version": "0.15.7",
-      "resolved": "https://registry.npmjs.org/bs-webapi/-/bs-webapi-0.15.7.tgz",
-      "integrity": "sha512-Mu8H+9DRIPK6VuqgzyUp5FoeBLSlhOqQcqc6G05At019kIZowQU783MoSedTbt9OctE9N1yO91DoDzMTWHspdg==",
-      "dev": true
-    },
-    "buffer-from": {
-      "version": "1.1.1",
-      "resolved": "https://registry.npmjs.org/buffer-from/-/buffer-from-1.1.1.tgz",
-      "integrity": "sha512-MQcXEUbCKtEo7bhqEs6560Hyd4XaovZlO/k9V3hjVUF/zwW7KBVdSK4gIt/bzwS9MbR5qob+F5jusZsb0YQK2A==",
-      "dev": true
-    },
-    "builtin-modules": {
-      "version": "3.1.0",
-      "resolved": "https://registry.npmjs.org/builtin-modules/-/builtin-modules-3.1.0.tgz",
-      "integrity": "sha512-k0KL0aWZuBt2lrxrcASWDfwOLMnodeQjodT/1SxEQAXsHANgo6ZC/VEaSEHCXt7aSTZ4/4H5LKa+tBXmW7Vtvw==",
-      "dev": true
-    },
-    "commander": {
-      "version": "2.20.3",
-      "resolved": "https://registry.npmjs.org/commander/-/commander-2.20.3.tgz",
-      "integrity": "sha512-GpVkmM8vF2vQUkj2LvZmD35JxeJOLCwJ9cUkugyk2nuhbv3+mJvpLYYt+0+USMxE+oj+ey/lJEnhZw75x/OMcQ==",
-      "dev": true
-    },
-    "estree-walker": {
-      "version": "1.0.1",
-      "resolved": "https://registry.npmjs.org/estree-walker/-/estree-walker-1.0.1.tgz",
-      "integrity": "sha512-1fMXF3YP4pZZVozF8j/ZLfvnR8NSIljt56UhbZ5PeeDmmGHpgpdwQt7ITlGvYaQukCvuBRMLEiKiYC+oeIg4cg==",
-      "dev": true
-    },
-    "is-module": {
-      "version": "1.0.0",
-      "resolved": "https://registry.npmjs.org/is-module/-/is-module-1.0.0.tgz",
-      "integrity": "sha1-Mlj7afeMFNW4FdZkM2tM/7ZEFZE=",
-      "dev": true
-    },
-    "path-parse": {
-      "version": "1.0.6",
-      "resolved": "https://registry.npmjs.org/path-parse/-/path-parse-1.0.6.tgz",
-      "integrity": "sha512-GSmOT2EbHrINBf9SR7CDELwlJ8AENk3Qn7OikK4nFYAu3Ote2+JYNVvkpAEQm3/TLNEJFD/xZJjzyxg3KBWOzw==",
-      "dev": true
-    },
-    "resolve": {
-      "version": "1.15.1",
-      "resolved": "https://registry.npmjs.org/resolve/-/resolve-1.15.1.tgz",
-      "integrity": "sha512-84oo6ZTtoTUpjgNEr5SJyzQhzL72gaRodsSfyxC/AXRvwu0Yse9H8eF9IpGo7b8YetZhlI6v7ZQ6bKBFV/6S7w==",
-      "dev": true,
-      "requires": {
-        "path-parse": "^1.0.6"
-      }
-    },
-    "rollup": {
-      "version": "1.31.1",
-      "resolved": "https://registry.npmjs.org/rollup/-/rollup-1.31.1.tgz",
-      "integrity": "sha512-2JREN1YdrS/kpPzEd33ZjtuNbOuBC3ePfuZBdKEybvqcEcszW1ckyVqzcEiEe0nE8sqHK+pbJg+PsAgRJ8+1dg==",
-      "dev": true,
-      "requires": {
-        "@types/estree": "*",
-        "@types/node": "*",
-        "acorn": "^7.1.0"
-      }
-    },
-    "source-map": {
-      "version": "0.6.1",
-      "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",
-      "integrity": "sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==",
-      "dev": true
-    },
-    "source-map-support": {
-      "version": "0.5.16",
-      "resolved": "https://registry.npmjs.org/source-map-support/-/source-map-support-0.5.16.tgz",
-      "integrity": "sha512-efyLRJDr68D9hBBNIPWFjhpFzURh+KJykQwvMyW5UiZzYwoF6l4YMMDIJJEyFWxWCqfyxLzz6tSfUFR+kXXsVQ==",
-      "dev": true,
-      "requires": {
-        "buffer-from": "^1.0.0",
-        "source-map": "^0.6.0"
-      }
-    },
-    "terser": {
-      "version": "4.6.3",
-      "resolved": "https://registry.npmjs.org/terser/-/terser-4.6.3.tgz",
-      "integrity": "sha512-Lw+ieAXmY69d09IIc/yqeBqXpEQIpDGZqT34ui1QWXIUpR2RjbqEkT8X7Lgex19hslSqcWM5iMN2kM11eMsESQ==",
-      "dev": true,
-      "requires": {
-        "commander": "^2.20.0",
-        "source-map": "~0.6.1",
-        "source-map-support": "~0.5.12"
-      }
-    }
-  }
-}
diff --git a/package.json b/package.json
deleted file mode 100644
index ce08644..0000000
--- a/package.json
+++ /dev/null
@@ -1,14 +0,0 @@
-{
-  "name": "tabata-timer",
-  "version": "0.1.0",
-  "keywords": [],
-  "author": "Joris Guyonvarch",
-  "license": "MIT",
-  "devDependencies": {
-    "@rollup/plugin-node-resolve": "^7.1.1",
-    "bs-platform": "^7.0.1",
-    "bs-webapi": "^0.15.7",
-    "rollup": "^1.31.0",
-    "terser": "^4.6.3"
-  }
-}
diff --git a/public/index.html b/public/index.html
index 6cf6562..a57c5c2 100644
--- a/public/index.html
+++ b/public/index.html
@@ -1,21 +1,27 @@
-<!DOCTYPE html>
+<!doctype html>
 <html lang="fr">
+<meta charset="utf-8">
+<meta name="viewport" content="width=device-width">
+<title>Tabata Timer</title>
+<link rel="stylesheet" href="/main.css">
+<link rel="icon" href="/icon.png">
 
-  <head>
-    <meta charset="utf-8">
-    <meta name="viewport" content="width=device-width, initial-scale=1">
-    <title>Tabata timer</title>
-    <link rel="stylesheet" href="main.css" />
-    <link rel="icon" href="/icon.png">
-  </head>
+<body>
+  <script>
+    // https://github.com/al6x/stupid&#45;simple&#45;typescript&#45;web&#45;starter
+    window.define = function(name, required, moduleFn) {
+      var require = function() { throw new Error("AMD require not supported!")}
+      var exports = window.define.modules[name] = {}
+      var resolved = [require, exports]
+      for (var i = 2; i < required.length; i++) {
+        var m = window.define.modules[required[i]]
+        if (!m) throw new Error("AMD module `" + required[i] + "` not found!")
+        resolved.push(m)
+      }
+      moduleFn.apply(null, resolved)
+    }
+    window.define.modules = {}
+  </script>
 
-  <body>
-
-    <main id="g-Layout__Main">
-    </main>
-
-    <script src="main.js"></script>
-
-  </body>
-
-</html>
+  <script src="main.js"></script>
+</body>
diff --git a/public/main.css b/public/main.css
index f1efc26..5df74af 100644
--- a/public/main.css
+++ b/public/main.css
@@ -10,15 +10,17 @@ html {
 /* Constants */
 
 :root {
+  --color-active: #F3E87F;
   --color-header: #333333;
-  --color-action: #993333;
-  --color-action-darker: #773333;
-  --color-timer-arc-total: #EEEEEE;
-  --color-timer-arc-progress: #71b571;
+  --color-action: #333333;
+  --color-action-darker: #222222;
+  --color-prepare: #3B6EDC;
+  --color-pause: #888888;
+  --color-work: #71b571;
+  --color-rest: #B15B5B;
+  --color-timer-arc-total: #222222;
   --color-timer-hover: #DDEEDD;
 
-  --dial-width: 20rem;
-
   --base-font-size: 18px;
 }
 
@@ -38,6 +40,11 @@ body {
   margin: 0;
 }
 
+.g-Layout__Page {
+  height: 100vh;
+  overflow-y: auto;
+}
+
 .g-Layout__Header {
   background-color: var(--color-header);
   color: white;
@@ -113,26 +120,42 @@ body {
 /* Timer */
 
 .g-Timer {
-  min-height: 100vh;
-  display: flex;
-  flex-direction: column;
-  align-items: center;
-  background-color: var(--color-header);
+  display: grid;
+  grid-template-columns: 10% auto 10%;
+  grid-template-rows: 10% auto 10% 10% 10%;
   color: white;
 }
 
+.g-Timer--Work {
+  background-color: var(--color-work);
+}
+
+.g-Timer--Rest {
+  background-color: var(--color-rest);
+}
+
+.g-Timer--Prepare {
+  background-color: var(--color-prepare);
+}
+
+.g-Timer__Pause {
+  background-color: var(--color-pause);
+}
+
 .g-Timer__Dial {
   display: flex;
   align-items: center;
   justify-content: center;
   flex-direction: column;
-  width: var(--dial-width);
-  height: var(--dial-width);
-  cursor: pointer;
+
+  width: 100%;
+  height: 100%;
+  grid-row: 2;
+  grid-column: 2;
+
   background-color: transparent;
   color: inherit;
   font-size: 3rem;
-  margin: 2rem 0;
   position: relative;
   border: none;
 }
@@ -148,45 +171,66 @@ body {
 .g-Timer__ArcTotal {
   stroke: var(--color-timer-arc-total);
   fill: none;
-  stroke-width: 10;
+  stroke-width: 20;
 }
 
-.g-Timer__ArcProgress {
-  stroke: var(--color-timer-arc-progress);
+.g-Timer__ArcPrepare {
+  stroke: var(--color-prepare);
   fill: none;
-  stroke-width: 10;
+  stroke-width: 18;
 }
 
-.g-Timer__Step {
-  margin-bottom: 0.5rem;
+.g-Timer__ArcWork {
+  stroke: var(--color-work);
+  fill: none;
+  stroke-width: 18;
 }
 
-.g-Timer__Duration:hover {
-  background-color: var(--color-timer-hover);
-  color: initial;
+.g-Timer__ArcRest {
+  stroke: var(--color-rest);
+  fill: none;
+  stroke-width: 18;
 }
 
-.g-Timer__TabataAndCycle {
-  display: flex;
-  justify-content: space-around;
-  font-size: 1.5rem;
-  width: var(--dial-width);
+.g-Timer__ArcProgress {
+  stroke: var(--color-active);
+  fill: none;
+  stroke-width: 18;
 }
 
-.g-Timer__Tabata,
-.g-Timer__Cycle {
-  text-align: center;
-  margin-bottom: 1rem;
+.g-Timer__Step {
+  margin-bottom: 2rem;
 }
 
-.g-Timer__Stop {
+.g-Timer__Buttons {
+  display: flex;
+  justify-content: space-around;
+  grid-row: 4;
+  grid-column: 2;
+  width: 100%;
+  height: 100%;
+}
+
+.g-Timer__Button {
+  display: flex;
+  justify-content: center;
+  align-items: center;
   font-size: 1.5rem;
   background-color: var(--color-action);
   border: 3px solid var(--color-action-darker);
   color: white;
   padding: 0.5rem 0.8rem;
   width: 10rem;
-  margin-top: 2rem;
   cursor: pointer;
   text-align: center;
+  text-decoration: none;
+}
+
+.g-Timer__Button:not(:last-child) {
+  margin-right: 2rem;
+}
+
+.g-Timer__Button--Active {
+  background-color: var(--color-active);
+  color: black;
 }
diff --git a/public/sound/end-tabata.mp3 b/public/sound/end-tabata.mp3
new file mode 100644
index 0000000..860c703
--- /dev/null
+++ b/public/sound/end-tabata.mp3
diff --git a/public/sound/end-training.mp3 b/public/sound/end-training.mp3
new file mode 100644
index 0000000..8af4c27
--- /dev/null
+++ b/public/sound/end-training.mp3
diff --git a/public/sound/start.mp3 b/public/sound/start.mp3
new file mode 100644
index 0000000..05aee23
--- /dev/null
+++ b/public/sound/start.mp3
diff --git a/public/sound/stop.mp3 b/public/sound/stop.mp3
new file mode 100644
index 0000000..c618f28
--- /dev/null
+++ b/public/sound/stop.mp3
diff --git a/public/sounds/c3.mp3 b/public/sounds/c3.mp3
deleted file mode 100644
index 13e661a..0000000
--- a/public/sounds/c3.mp3
+++ /dev/null
diff --git a/public/sounds/c4.mp3 b/public/sounds/c4.mp3
deleted file mode 100644
index 0266119..0000000
--- a/public/sounds/c4.mp3
+++ /dev/null
diff --git a/public/sounds/c5.mp3 b/public/sounds/c5.mp3
deleted file mode 100644
index 8ff926e..0000000
--- a/public/sounds/c5.mp3
+++ /dev/null
diff --git a/rollup.config.js b/rollup.config.js
deleted file mode 100644
index c59bd7b..0000000
--- a/rollup.config.js
+++ /dev/null
@@ -1,13 +0,0 @@
-import resolve from '@rollup/plugin-node-resolve';
-
-export default {
-  input: 'src/main.bs.js',
-  output: {
-    name: 'tabata_timer',
-    file: 'public/main.js',
-    format: 'iife'
-  },
-  plugins: [
-    resolve()
-  ]
-};
diff --git a/shell.nix b/shell.nix
index a2d442a..ad4a34d 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,17 +1,16 @@
-with import (builtins.fetchTarball {
-  # https://github.com/NixOS/nixpkgs/commit/77752c6c086512a7c1eb066edcef731696fa2a8e
-  name = "nixpkgs-20-12-2019";
-  url = https://github.com/nixos/nixpkgs/archive/77752c6c086512a7c1eb066edcef731696fa2a8e.tar.gz;
-  sha256 = "1sb6c9pzq4rjc8sj41qw01b38119xk91pmlxwl80fqhg8mj1ai8r";
-}) {};
+with (import (builtins.fetchGit {
+  name = "nixpkgs-20.09";
+  url = "git@github.com:nixos/nixpkgs.git";
+  rev = "cd63096d6d887d689543a0b97743d28995bc9bc3";
+  ref = "refs/tags/20.09";
+}){});
 
 mkShell {
+
   buildInputs = [
-    bs-platform
-    nodejs
-    tmux
-    tmuxinator
-    ocamlformat
+    nodePackages.typescript
     python3
+    psmisc # fuser
   ];
+
 }
diff --git a/src/Dom/CreateElement.ml b/src/Dom/CreateElement.ml
deleted file mode 100644
index 8183a02..0000000
--- a/src/Dom/CreateElement.ml
+++ /dev/null
@@ -1,72 +0,0 @@
-(* Element creation *)
-
-let h tag ?(attributes = [||]) ?(eventListeners = [||]) ?(children = [||]) () :
-    Dom.element =
-  let element =
-    if tag == "svg" || tag == "path" then
-      Document.createElementNS "http://www.w3.org/2000/svg" tag
-    else Document.createElement tag
-  in
-  let () =
-    Js.Array.forEach
-      (fun (name, value) -> Element.setAttribute element name value)
-      attributes
-  in
-  let () =
-    Js.Array.forEach
-      (fun (name, eventListener) ->
-        Element.addEventListener element name eventListener)
-      eventListeners
-  in
-  let () =
-    Js.Array.forEach (fun child -> Element.appendChild element child) children
-  in
-  element
-
-(* Node creation *)
-
-let text = Document.createTextNode
-
-let div = h "div"
-
-let span = h "span"
-
-let header = h "header"
-
-let button = h "button"
-
-let section = h "section"
-
-let svg = h "svg"
-
-let path = h "path"
-
-let form = h "form"
-
-let label = h "label"
-
-let input_ = h "input"
-
-(* Attribute creation *)
-
-let id v = ("id", v)
-
-let className v = ("class", v)
-
-let viewBox v = ("viewBox", v)
-
-let d v = ("d", v)
-
-let type_ v = ("type", v)
-
-let min_ v = ("min", v)
-
-let value v = ("value", v)
-
-(* Event listeners *)
-
-let onClick f = ("click", f)
-
-let onInput f = ("input", f)
-
-let onSubmit f = ("submit", f)
diff --git a/src/Dom/Document.ml b/src/Dom/Document.ml
deleted file mode 100644
index 867e28c..0000000
--- a/src/Dom/Document.ml
+++ /dev/null
@@ -1,14 +0,0 @@
-external createElement : string -> Dom.element = "createElement"
-  [@@bs.val] [@@bs.scope "document"]
-
-external createElementNS : string -> string -> Dom.element = "createElementNS"
-  [@@bs.val] [@@bs.scope "document"]
-
-external querySelector : string -> Dom.element Js.Nullable.t = "querySelector"
-  [@@bs.val] [@@bs.scope "document"]
-
-let querySelectorUnsafe id =
-  querySelector id |> Js.Nullable.toOption |> Js.Option.getExn
-
-external createTextNode : string -> Dom.element = "createTextNode"
-  [@@bs.val] [@@bs.scope "document"]
diff --git a/src/Dom/Element.ml b/src/Dom/Element.ml
deleted file mode 100644
index 0b6c0bd..0000000
--- a/src/Dom/Element.ml
+++ /dev/null
@@ -1,44 +0,0 @@
-external setValue : Dom.element -> string -> unit = "value" [@@bs.set]
-
-external setTextContent : Dom.element -> string -> unit = "textContent"
-  [@@bs.set]
-
-external setStyle : Dom.element -> string -> unit = "style" [@@bs.set]
-
-external setClassName : Dom.element -> string -> unit = "className" [@@bs.set]
-
-external setScrollTop : Dom.element -> int -> unit = "scrollTop" [@@bs.set]
-
-external setAttribute : Dom.element -> string -> string -> unit = "setAttribute"
-  [@@bs.send]
-
-external setAttributeNS : Dom.element -> string -> string -> string -> unit
-  = "setAttributeNS"
-  [@@bs.send]
-
-external addEventListener : Dom.element -> string -> (Dom.event -> unit) -> unit
-  = "addEventListener"
-  [@@bs.send]
-
-external appendChild : Dom.element -> Dom.element -> unit = "appendChild"
-  [@@bs.send]
-
-external firstChild : Dom.element -> Dom.element Js.Nullable.t = "firstChild"
-  [@@bs.get]
-
-external removeChild : Dom.element -> Dom.element -> unit = "removeChild"
-  [@@bs.send]
-
-let removeFirstChild element =
-  match Js.toOption (firstChild element) with
-  | Some child ->
-      let () = removeChild element child in
-      true
-  | _ -> false
-
-let rec removeChildren element =
-  if removeFirstChild element then removeChildren element else ()
-
-let mountOn base element =
-  let () = removeChildren base in
-  appendChild base element
diff --git a/src/Dom/Event.ml b/src/Dom/Event.ml
deleted file mode 100644
index bffd242..0000000
--- a/src/Dom/Event.ml
+++ /dev/null
@@ -1,3 +0,0 @@
-external preventDefault : Dom.event -> unit = "preventDefault" [@@bs.send]
-
-external target : Dom.event -> Dom.eventTarget = "target" [@@bs.get]
diff --git a/src/Dom/EventTarget.ml b/src/Dom/EventTarget.ml
deleted file mode 100644
index d1b0c02..0000000
--- a/src/Dom/EventTarget.ml
+++ /dev/null
@@ -1,4 +0,0 @@
-external nullableValue : Dom.eventTarget -> string Js.Nullable.t = "value"
-  [@@bs.get]
-
-let value eventTarget = nullableValue eventTarget |> Js.Nullable.toOption
diff --git a/src/Model/config.ml b/src/Model/config.ml
deleted file mode 100644
index 99e42d1..0000000
--- a/src/Model/config.ml
+++ /dev/null
@@ -1,12 +0,0 @@
-type config = {
-  prepare : int;
-  tabatas : int;
-  cycles : int;
-  work : int;
-  rest : int;
-}
-
-let init = { prepare = 10; tabatas = 4; cycles = 8; work = 20; rest = 10 }
-
-let getDuration { prepare; tabatas; cycles; work; rest } =
-  tabatas * (prepare + (cycles * (work + rest)))
diff --git a/src/Model/step.ml b/src/Model/step.ml
deleted file mode 100644
index 02a110e..0000000
--- a/src/Model/step.ml
+++ /dev/null
@@ -1,40 +0,0 @@
-type step = Prepare | Work | Rest | End
-
-let prettyPrint step =
-  match step with
-  | Prepare -> "Prepare"
-  | Work -> "Work"
-  | Rest -> "Rest"
-  | End -> "End"
-
-type state = { step : step; remaining : int; tabata : int; cycle : int }
-
-let getAt (config : Config.config) elapsed =
-  let cycleDuration = config.work + config.rest in
-  let tabataDuration = config.prepare + (config.cycles * cycleDuration) in
-  if elapsed >= tabataDuration * config.tabatas then
-    {
-      step = End;
-      remaining = 0;
-      tabata = config.tabatas;
-      cycle = config.cycles;
-    }
-  else
-    let currentTabataElapsed = elapsed mod tabataDuration in
-    let step, remaining =
-      if currentTabataElapsed < config.prepare then
-        (Prepare, config.prepare - currentTabataElapsed)
-      else
-        let currentCycleElapsed =
-          (currentTabataElapsed - config.prepare) mod cycleDuration
-        in
-        if currentCycleElapsed < config.work then
-          (Work, config.work - currentCycleElapsed)
-        else (Rest, config.work + config.rest - currentCycleElapsed)
-    in
-    let tabata = (elapsed / tabataDuration) + 1 in
-    let cycle =
-      if currentTabataElapsed < config.prepare then 1
-      else ((currentTabataElapsed - config.prepare) / cycleDuration) + 1
-    in
-    { step; remaining; tabata; cycle }
diff --git a/src/View/configView.ml b/src/View/configView.ml
deleted file mode 100644
index 5db6ea5..0000000
--- a/src/View/configView.ml
+++ /dev/null
@@ -1,83 +0,0 @@
-open CreateElement
-open Config
-
-let labelledInput labelValue minValue inputValue update writeDuration =
-  label
-    ~attributes:[| className "g-Form__Label" |]
-    ~eventListeners:
-      [|
-        onInput (fun e ->
-            match
-              EventTarget.value (Event.target e)
-              |> Option.flatMap Belt.Int.fromString
-            with
-            | Some n ->
-                let () = update n in
-                writeDuration ()
-            | None -> ());
-      |]
-    ~children:
-      [|
-        text labelValue;
-        input_
-          ~attributes:
-            [|
-              className "g-Form__Input";
-              type_ "number";
-              min_ (Js.Int.toString minValue);
-              value (Js.Int.toString inputValue);
-            |]
-          ();
-      |]
-    ()
-
-let render initialConfig onStart =
-  let config = ref initialConfig in
-  let duration = text (Duration.prettyPrint (getDuration !config)) in
-  let wd () =
-    Element.setTextContent duration (Duration.prettyPrint (getDuration !config))
-  in
-  div
-    ~children:
-      [|
-        header
-          ~attributes:[| className "g-Layout__Header" |]
-          ~children:[| text "Tabata timer" |]
-          ();
-        form
-          ~attributes:[| className "g-Form" |]
-          ~eventListeners:
-            [|
-              onSubmit (fun e ->
-                  let () = Event.preventDefault e in
-                  onStart !config);
-            |]
-          ~children:
-            [|
-              labelledInput "prepare" 0 !config.prepare
-                (fun n -> config := { !config with prepare = n })
-                wd;
-              labelledInput "tabatas" 1 !config.tabatas
-                (fun n -> config := { !config with tabatas = n })
-                wd;
-              labelledInput "cycles" 1 !config.cycles
-                (fun n -> config := { !config with cycles = n })
-                wd;
-              labelledInput "work" 5 !config.work
-                (fun n -> config := { !config with work = n })
-                wd;
-              labelledInput "rest" 5 !config.rest
-                (fun n -> config := { !config with rest = n })
-                wd;
-              div
-                ~attributes:[| className "g-Form__Duration" |]
-                ~children:[| text "duration"; div ~children:[| duration |] () |]
-                ();
-              button
-                ~attributes:[| className "g-Form__Start" |]
-                ~children:[| text "start" |]
-                ();
-            |]
-          ();
-      |]
-    ()
diff --git a/src/View/timerView.ml b/src/View/timerView.ml
deleted file mode 100644
index 2384f85..0000000
--- a/src/View/timerView.ml
+++ /dev/null
@@ -1,123 +0,0 @@
-open CreateElement
-
-let render (config : Config.config) onStop =
-  let duration = Config.getDuration config in
-  (* State *)
-  let interval = ref None in
-  let elapsed = ref 0 in
-  let step = ref (Step.getAt config !elapsed) in
-  let isPlaying = ref true in
-  (* Elements *)
-  let stepElt = text (Step.prettyPrint !step.step) in
-  let durationElt = text (Duration.prettyPrint !step.remaining) in
-  let arcPathElt = path ~attributes:[| className "g-Timer__ArcProgress" |] () in
-  let tabataCurrentElt = text (Js.Int.toString !step.tabata) in
-  let cycleCurrentElt = text (Js.Int.toString !step.cycle) in
-  (* Update *)
-  let stop () =
-    let () = Belt.Option.forEach !interval Js.Global.clearInterval in
-    onStop config
-  in
-  let updateDom () =
-    let angle = Js.Int.toFloat !elapsed /. Js.Int.toFloat duration *. 360.0 in
-    let () =
-      Element.setAttribute arcPathElt "d" (Arc.describe 0.0 0.0 95.0 0.0 angle)
-    in
-    let step = Step.getAt config !elapsed in
-    let () = Element.setTextContent stepElt (Step.prettyPrint step.step) in
-    let () =
-      Element.setTextContent durationElt (Duration.prettyPrint step.remaining)
-    in
-    let () =
-      Element.setTextContent tabataCurrentElt (Js.Int.toString step.tabata)
-    in
-    let () =
-      Element.setTextContent cycleCurrentElt (Js.Int.toString step.cycle)
-    in
-    Audio.playFromStep config step
-  in
-  let update () =
-    if !isPlaying then
-      let () = elapsed := !elapsed + 1 in
-      let () = step := Step.getAt config !elapsed in
-      if !elapsed > duration then stop () else updateDom ()
-    else ()
-  in
-  (* Start timer *)
-  let () = interval := Some (Js.Global.setInterval update 1000) in
-  (* View *)
-  section
-    ~attributes:[| className "g-Timer" |]
-    ~children:
-      [|
-        button
-          ~attributes:[| className "g-Timer__Dial" |]
-          ~eventListeners:[| onClick (fun _ -> isPlaying := not !isPlaying) |]
-          ~children:
-            [|
-              svg
-                ~attributes:
-                  [| className "g-Timer__Arc"; viewBox "-100 -100 200 200" |]
-                ~children:
-                  [|
-                    path
-                      ~attributes:
-                        [|
-                          className "g-Timer__ArcTotal";
-                          d (Arc.describe 0.0 0.0 95.0 0.0 359.999);
-                        |]
-                      ();
-                    arcPathElt;
-                  |]
-                ();
-              div
-                ~attributes:[| className "g-Timer__Step" |]
-                ~children:[| stepElt |] ();
-              div
-                ~attributes:[| className "g-Timer__Duration" |]
-                ~children:[| durationElt |] ();
-            |]
-          ();
-        div
-          ~attributes:[| className "g-Timer__TabataAndCycle" |]
-          ~children:
-            [|
-              div
-                ~attributes:[| className "g-Timer__Tabata" |]
-                ~children:
-                  [|
-                    div ~children:[| text "Tabata" |] ();
-                    span
-                      ~attributes:[| className "g-Timer__TabataCurrent" |]
-                      ~children:[| tabataCurrentElt |] ();
-                    text "/";
-                    span
-                      ~attributes:[| className "g-Timer__TabataTotal" |]
-                      ~children:[| text (Js.Int.toString config.tabatas) |]
-                      ();
-                  |]
-                ();
-              div
-                ~attributes:[| className "g-Timer__Cycle" |]
-                ~children:
-                  [|
-                    div ~children:[| text "Cycle" |] ();
-                    span
-                      ~attributes:[| className "g-Timer__CycleCurrent" |]
-                      ~children:[| cycleCurrentElt |] ();
-                    text "/";
-                    span
-                      ~attributes:[| className "g-Timer__CycleTotal" |]
-                      ~children:[| text (Js.Int.toString config.cycles) |]
-                      ();
-                  |]
-                ();
-            |]
-          ();
-        div
-          ~attributes:[| className "g-Timer__Stop" |]
-          ~children:[| text "stop" |]
-          ~eventListeners:[| onClick (fun _ -> stop ()) |]
-          ();
-      |]
-    ()
diff --git a/src/animation.ml b/src/animation.ml
deleted file mode 100644
index 35294dc..0000000
--- a/src/animation.ml
+++ /dev/null
@@ -1,27 +0,0 @@
-let isRunning = ref false
-
-let start base ~onStart ~onEnd =
-  if not !isRunning then
-    let () = isRunning := true in
-    let () = onStart () in
-    let () = Element.setClassName base "g-Animation" in
-    let delay = 400 in
-    let _ =
-      Js.Global.setTimeout
-        (fun () ->
-          let () = Element.setClassName base "" in
-          let () = onEnd () in
-          isRunning := false)
-        delay
-    in
-    ()
-  else ()
-
-let replaceChild scrollBase base mkChild =
-  start base
-    ~onStart:(fun _ ->
-      let () = Element.setScrollTop scrollBase 0 in
-      Element.appendChild base (mkChild ()))
-    ~onEnd:(fun _ ->
-      let _ = Element.removeFirstChild base in
-      ())
diff --git a/src/arc.ml b/src/arc.ml
deleted file mode 100644
index 7a3195d..0000000
--- a/src/arc.ml
+++ /dev/null
@@ -1,23 +0,0 @@
-let polarToCartesian centerX centerY radius angleInDegrees =
-  let angleInRadians = (angleInDegrees -. 90.0) *. Js.Math._PI /. 180.0 in
-  ( centerX +. (radius *. Js.Math.cos angleInRadians),
-    centerY +. (radius *. Js.Math.sin angleInRadians) )
-
-let describe x y radius startAngle endAngle =
-  let startX, startY = polarToCartesian x y radius endAngle in
-  let endX, endY = polarToCartesian x y radius startAngle in
-  let largeArcFlag = if endAngle -. startAngle <= 180.0 then "0" else "1" in
-  [|
-    "M";
-    Js.Float.toString startX;
-    Js.Float.toString startY;
-    "A";
-    Js.Float.toString radius;
-    Js.Float.toString radius;
-    "0";
-    largeArcFlag;
-    "0";
-    Js.Float.toString endX;
-    Js.Float.toString endY;
-  |]
-  |> Js.Array.joinWith " "
diff --git a/src/arc.ts b/src/arc.ts
new file mode 100644
index 0000000..d8e1e7d
--- /dev/null
+++ b/src/arc.ts
@@ -0,0 +1,37 @@
+function polarToCartesian(
+  centerX: number,
+  centerY: number,
+  radius: number,
+  degreesAngle: number
+): number[] {
+  const radianAngle = (degreesAngle - 90) * Math.PI / 180
+  return [
+    centerX + radius * Math.cos(radianAngle),
+    centerY + radius * Math.sin(radianAngle)
+  ]
+}
+
+export function describe(
+  x: number,
+  y: number,
+  radius: number,
+  startAngle: number,
+  endAngle: number
+): string {
+  const [startX, startY] = polarToCartesian(x, y, radius, endAngle)
+  const [endX, endY] = polarToCartesian(x, y, radius, startAngle)
+  const largeArcFlag = endAngle - startAngle <= 180 ? "0" : "1"
+  return [
+    "M",
+    startX.toString(),
+    startY,
+    "A",
+    radius.toString(),
+    radius.toString(),
+    "0",
+    largeArcFlag,
+    "0",
+    endX.toString(),
+    endY.toString(),
+  ].join(" ")
+}
diff --git a/src/audio.ml b/src/audio.ml
deleted file mode 100644
index 1446440..0000000
--- a/src/audio.ml
+++ /dev/null
@@ -1,34 +0,0 @@
-type audio
-
-external create : string -> audio = "Audio" [@@bs.new]
-
-external play : audio -> unit = "play" [@@bs.send]
-
-external currentTime : audio -> int = "currentTime" [@@bs.get]
-
-external setCurrentTime : audio -> int -> unit = "currentTime" [@@bs.set]
-
-let playOrReplay audio =
-  let () = if currentTime audio > 0 then setCurrentTime audio 0 else () in
-  play audio
-
-(* Sounds *)
-
-let c3 = create "sounds/c3.mp3"
-
-let c4 = create "sounds/c4.mp3"
-
-let c5 = create "sounds/c5.mp3"
-
-(* Play from step *)
-
-let playFromStep (config: Config.config) (step : Step.state) =
-  match step.step with
-  | Step.Prepare when step.remaining == config.prepare ->
-      playOrReplay c3
-  | Step.Work when step.remaining == config.work ->
-      playOrReplay c5
-  | Step.Rest when step.remaining == config.rest ->
-      playOrReplay c3
-  | Step.End -> playOrReplay c3
-  | _ -> if step.remaining <= 3 then playOrReplay c4 else ()
diff --git a/src/audio.ts b/src/audio.ts
new file mode 100644
index 0000000..bdf64eb
--- /dev/null
+++ b/src/audio.ts
@@ -0,0 +1,19 @@
+import * as Config from 'config'
+import * as State from 'state'
+
+const start = new Audio('sound/start.mp3')
+const stop = new Audio('sound/stop.mp3')
+const endTabata = new Audio('sound/end-tabata.mp3')
+const endTraining = new Audio('sound/end-training.mp3')
+
+export function playFromStep(config: Config.Config, state: State.State) {
+  if (state.step === State.Step.Work && state.remaining === config.work) {
+    start.play()
+  } else if (state.step === State.Step.Rest && state.remaining === config.rest) {
+    stop.play()
+  } else if (state.step === State.Step.Prepare && state.remaining === config.prepare) {
+    endTabata.play()
+  } else if (state.step === State.Step.End) {
+    endTraining.play()
+  }
+}
diff --git a/src/config.ts b/src/config.ts
new file mode 100644
index 0000000..c20bff2
--- /dev/null
+++ b/src/config.ts
@@ -0,0 +1,21 @@
+export interface Config {
+  prepare : number;
+  tabatas : number;
+  cycles : number;
+  work : number;
+  rest : number;
+}
+
+export function init(): Config {
+  return {
+    prepare: 10,
+    tabatas: 4,
+    cycles: 8,
+    work: 20,
+    rest: 10
+  }
+}
+
+export function getDuration(c: Config): number {
+  return c.tabatas * (c.prepare + (c.cycles * (c.work + c.rest)))
+}
diff --git a/src/duration.ml b/src/duration.ml
deleted file mode 100644
index b0b119b..0000000
--- a/src/duration.ml
+++ /dev/null
@@ -1,6 +0,0 @@
-let prettyPrintNumber number = String.padStart (Js.Int.toString number) 2 "0"
-
-let prettyPrint duration =
-  let minutes = duration / 60 in
-  let seconds = duration mod 60 in
-  prettyPrintNumber minutes ^ ":" ^ prettyPrintNumber seconds
diff --git a/src/duration.ts b/src/duration.ts
new file mode 100644
index 0000000..92952a7
--- /dev/null
+++ b/src/duration.ts
@@ -0,0 +1,9 @@
+function prettyPrintNumber(n: number): string {
+  return n.toString().padStart(2, "0")
+}
+
+export function prettyPrint(duration: number): string {
+  const minutes = Math.floor(duration / 60)
+  const seconds = duration % 60
+  return prettyPrintNumber(minutes) + ":" + prettyPrintNumber(seconds)
+}
diff --git a/src/h.ts b/src/h.ts
new file mode 100644
index 0000000..bb21efd
--- /dev/null
+++ b/src/h.ts
@@ -0,0 +1,30 @@
+type Child = Element | Text | string | number
+
+export default function h(
+  tagName: string,
+  attrs: object,
+  ...children: Child[]
+): Element {
+  const isSvg = tagName === 'svg' || tagName === 'path'
+
+  let elem = isSvg
+    ? document.createElementNS('http://www.w3.org/2000/svg', tagName)
+    : document.createElement(tagName)
+
+  if (isSvg) {
+    Object.entries(attrs).forEach(([key, value]) => {
+      elem.setAttribute(key, value)
+    })
+  } else {
+    elem = Object.assign(elem, attrs)
+  }
+
+  for (const child of children) {
+    if (typeof child === 'number')
+      elem.append(child.toString())
+    else
+      elem.append(child)
+  }
+
+  return elem
+}
diff --git a/src/main.ml b/src/main.ml
deleted file mode 100644
index 003880b..0000000
--- a/src/main.ml
+++ /dev/null
@@ -1,14 +0,0 @@
-type view = Config of Config.config | Timer of Config.config
-
-let () =
-  let html = Document.querySelectorUnsafe "html" in
-  let main = Document.querySelectorUnsafe "main" in
-  let rec showView v =
-    Animation.replaceChild html main (fun _ ->
-        match v with
-        | Config config ->
-            ConfigView.render config (fun config -> showView (Timer config))
-        | Timer config ->
-            TimerView.render config (fun config -> showView (Config config)))
-  in
-  showView (Config Config.init)
diff --git a/src/main.ts b/src/main.ts
new file mode 100644
index 0000000..436a217
--- /dev/null
+++ b/src/main.ts
@@ -0,0 +1,21 @@
+import * as Config from 'config'
+import * as Form from 'view/form'
+import * as Timer from 'view/timer'
+import * as Router from 'router'
+
+export function showPage(route: Router.Route) {
+  if (route.kind === Router.Kind.Form) {
+    document.body.innerHTML = ''
+    document.body.appendChild(Form.view(route.config, showPage))
+  } else if (route.kind === Router.Kind.Timer) {
+    document.body.innerHTML = ''
+    document.body.appendChild(Timer.view(route.config, showPage))
+  }
+}
+
+showPage(Router.from(document.location))
+
+window.onpopstate = (event: Event) => {
+  Timer.clearInterval()
+  showPage(Router.from(document.location))
+}
diff --git a/src/option.ml b/src/option.ml
deleted file mode 100644
index 16047fd..0000000
--- a/src/option.ml
+++ /dev/null
@@ -1 +0,0 @@
-let flatMap f opt = Belt.Option.flatMapU opt (fun [@bs] x -> f x)
diff --git a/src/router.ts b/src/router.ts
new file mode 100644
index 0000000..abbdc65
--- /dev/null
+++ b/src/router.ts
@@ -0,0 +1,55 @@
+import * as Config from 'config'
+
+export enum Kind {
+  Form,
+  Timer,
+}
+
+export interface Route {
+  kind: Kind,
+  config: Config.Config
+}
+
+export function from(location: Location): Route {
+  const hash = location.hash.slice(1)
+  const parts = hash.split('?')
+  const path = parts[0]
+  const search = parts.length > 1 ? parts[1] : ''
+
+  const kind = path.startsWith('/timer') ? Kind.Timer : Kind.Form
+  let config = Config.init()
+  if (search.length > 0) {
+    search.split('&').forEach(entry => {
+      const xs = entry.split('=')
+      if (xs.length === 2) {
+        const key = xs[0]
+        const value = parseInt(xs[1])
+        if (key == 'prepare') config.prepare = value
+        else if (key == 'tabatas') config.tabatas = value
+        else if (key == 'cycles') config.cycles = value
+        else if (key == 'work') config.work = value
+        else if (key == 'rest') config.rest = value
+      }
+    })
+    const params = search.split('&')
+  }
+
+  return { kind, config }
+}
+
+export function toString(route: Route): string {
+  const path = route.kind === Kind.Form ? '/' : '/timer'
+  let query = ''
+  if (route.config !== undefined) {
+    const { prepare, tabatas, cycles, work, rest } = route.config
+    const params = [
+      `prepare=${prepare}`,
+      `tabatas=${tabatas}`,
+      `cycles=${cycles}`,
+      `work=${work}`,
+      `rest=${rest}`,
+    ].join('&')
+    query = `?${params}`
+  }
+  return `#${path}${query}`
+}
diff --git a/src/state.ts b/src/state.ts
new file mode 100644
index 0000000..3b390c5
--- /dev/null
+++ b/src/state.ts
@@ -0,0 +1,63 @@
+import * as Config from 'config'
+
+export enum Step {
+  Prepare,
+  Work,
+  Rest,
+  End,
+}
+
+export function prettyPrintStep(step: Step): string {
+  if (step === Step.Prepare)
+    return "Prepare"
+  else if (step === Step.Work)
+    return "Work"
+  else if (step === Step.Rest)
+    return "Rest"
+  else
+    return "End"
+}
+
+export interface State {
+  step: Step,
+  remaining: number,
+  tabata: number,
+  cycle: number,
+}
+
+export function getAt(config: Config.Config, elapsed: number): State {
+  const cycleDuration = config.work + config.rest
+  const tabataDuration = config.prepare + (config.cycles * cycleDuration)
+  if (elapsed >= tabataDuration * config.tabatas) {
+    return {
+      step: Step.End,
+      remaining: 0,
+      tabata: config.tabatas,
+      cycle: config.cycles,
+    }
+  } else {
+    const currentTabataElapsed = elapsed % tabataDuration
+    let step, remaining
+    if (currentTabataElapsed < config.prepare) {
+      step = Step.Prepare
+      remaining = config.prepare - currentTabataElapsed
+    } else {
+      const currentCycleElapsed = (currentTabataElapsed - config.prepare) % cycleDuration
+      if (currentCycleElapsed < config.work) {
+        step = Step.Work
+        remaining = config.work - currentCycleElapsed
+      } else {
+        step = Step.Rest
+        remaining = config.work + config.rest - currentCycleElapsed
+      }
+    }
+
+    const tabata = Math.floor(elapsed / tabataDuration) + 1
+    const cycle =
+      currentTabataElapsed < config.prepare
+        ? 1
+        : Math.floor((currentTabataElapsed - config.prepare) / cycleDuration) + 1
+
+    return { step, remaining, tabata, cycle }
+  }
+}
diff --git a/src/string.ml b/src/string.ml
deleted file mode 100644
index 335fdec..0000000
--- a/src/string.ml
+++ /dev/null
@@ -1 +0,0 @@
-external padStart : string -> int -> string -> string = "padStart" [@@bs.send]
diff --git a/src/view/form.ts b/src/view/form.ts
new file mode 100644
index 0000000..60e5f08
--- /dev/null
+++ b/src/view/form.ts
@@ -0,0 +1,47 @@
+import * as Config from 'config'
+import h from 'h'
+import * as Router from 'router'
+import * as Duration from 'duration'
+
+function labelledInput(
+  labelValue: string,
+  min: number,
+  value: number,
+  update: (n: number) => void
+): Element {
+  return h('label',
+    { className: 'g-Form__Label',
+      oninput: (e: Event) => {
+        if (e.target !== null) {
+          const target = e.target as HTMLInputElement
+          update(parseInt(target.value) || 0)
+        }
+      }
+    },
+    labelValue,
+    h('input', { className: 'g-Form__Input', type: 'number', min, value }))
+}
+
+export function view(config: Config.Config, showPage: (route: Router.Route) => void) {
+  const duration = document.createTextNode(Duration.prettyPrint(Config.getDuration(config)))
+  const wd = () => duration.textContent = Duration.prettyPrint(Config.getDuration(config))
+  return h('div',
+    { className: 'g-Layout__Page' },
+      h('header', { className: 'g-Layout__Header' }, 'Tabata timer'),
+      h('form',
+        { className: 'g-Form'
+        , onsubmit: (e: Event) => {
+            e.preventDefault()
+            const timerRoute = { kind: Router.Kind.Timer, config }
+            history.pushState({}, '', Router.toString(timerRoute))
+            showPage(timerRoute)
+        }},
+        labelledInput('prepare', 0, config.prepare, n => { config.prepare = n; wd()}),
+        labelledInput('tabatas', 1, config.tabatas, n => { config.tabatas = n; wd()}),
+        labelledInput('cycles', 1, config.cycles, n => { config.cycles = n; wd()}),
+        labelledInput('work', 5, config.work, n => { config.work = n; wd()}),
+        labelledInput('rest', 5, config.rest, n => { config.rest = n; wd()}),
+        h('div', { className: 'g-Form__Duration' }, 'duration', h('div', {}, duration)),
+        h('button', { className: 'g-Form__Start' }, 'start'))
+  )
+}
diff --git a/src/view/timer.ts b/src/view/timer.ts
new file mode 100644
index 0000000..ddcea71
--- /dev/null
+++ b/src/view/timer.ts
@@ -0,0 +1,158 @@
+import * as Config from 'config'
+import * as State from 'state'
+import * as Arc from 'arc'
+import * as Router from 'router'
+import * as Audio from 'audio'
+import h from 'h'
+
+let interval: number | undefined = undefined
+
+export function clearInterval() {
+  if (interval !== undefined) {
+    window.clearInterval(interval)
+    interval = undefined
+  }
+}
+
+export function view(config: Config.Config, showPage: (route: Router.Route) => void) {
+
+  const formUrl = `${Router.toString({ kind: Router.Kind.Form, config })}`
+  const duration = Config.getDuration(config)
+
+  // State
+  let isPlaying = true
+  let elapsed = 0
+  let state = State.getAt(config, elapsed)
+
+  // Elements
+  const section = h('section', { className: timerClass(state.step) })
+  const stepElt = document.createTextNode(State.prettyPrintStep(state.step))
+  const stepCountElt = document.createTextNode(stepCount(state))
+  const arcPathElt = h('path', { class: 'g-Timer__ArcProgress' })
+
+  const updateDom = () => {
+    const angle = elapsed / duration * 360
+    arcPathElt.setAttribute("d", Arc.describe(0, 0, 90, 0, angle))
+    section.className = timerClass(state.step)
+    stepElt.textContent = State.prettyPrintStep(state.step)
+    stepCountElt.textContent = stepCount(state)
+    Audio.playFromStep(config, state)
+  }
+
+  const quit = () => {
+    const formRoute = { kind: Router.Kind.Form, config }
+    history.pushState({}, '', Router.toString(formRoute))
+    showPage(formRoute)
+  }
+
+  const update = () => {
+    if (isPlaying) {
+      elapsed = elapsed + 1
+      state = State.getAt(config, elapsed)
+      elapsed > duration
+        ? quit()
+        : updateDom()
+    }
+  }
+
+  // Start timer
+  if (interval !== undefined) {
+    window.clearInterval(interval)
+    interval = undefined
+  }
+  interval = window.setInterval(update, 1000)
+
+  section.append(
+    h('div',
+      { className: 'g-Timer__Dial' },
+      h('svg',
+        { class: 'g-Timer__Arc',
+          viewBox: '-100 -100 200 200'
+        },
+        h('path',
+          { class: 'g-Timer__ArcTotal',
+            d: Arc.describe(0, 0, 90.0, 0, 359.999)
+          }
+        ),
+        ...arcPaths(config),
+        arcPathElt
+      ),
+      h('div', { className: 'g-Timer__Step' }, stepElt),
+      h('div', {}, stepCountElt)
+    ),
+    h('div',
+      { className: 'g-Timer__Buttons' },
+      h('button',
+        { className: 'g-Timer__Button',
+          onclick: (e: MouseEvent) => {
+            isPlaying = !isPlaying
+            const elt = e.target as HTMLElement
+            elt.textContent = isPlaying
+              ? 'pause'
+              : 'resume'
+            elt.className = isPlaying
+              ? 'g-Timer__Button'
+              : 'g-Timer__Button g-Timer__Button--Active'
+          }
+        },
+        'pause'
+      ),
+      h('a',
+        { className: 'g-Timer__Button',
+          href: formUrl
+        },
+        'quit'
+      )
+    )
+  )
+
+  return section
+}
+
+function arcPaths(config: Config.Config): Element[] {
+  const paths = []
+
+  let t = 0
+  const totalDuration = Config.getDuration(config)
+
+  let arc = (kind: string, duration: number): Element => {
+    const startAngle = 360 * t / totalDuration
+    const endAngle = 360 * (t + duration) / totalDuration
+
+    t += duration
+
+    return h('path',
+      { class: `g-Timer__Arc${kind}`,
+        d: Arc.describe(0, 0, 90.0, startAngle, endAngle)
+      }
+    )
+  }
+
+  for (let tabata = 0; tabata < config.tabatas; tabata++) {
+    paths.push(arc('Prepare', config.prepare))
+    for (let cycle = 0; cycle < config.cycles; cycle++) {
+      paths.push(arc('Work', config.work))
+      paths.push(arc('Rest', config.rest))
+    }
+  }
+
+  return paths
+}
+
+function timerClass(step: State.Step): string {
+  if (step === State.Step.Work) {
+    return 'g-Layout__Page g-Timer g-Timer--Work'
+  } else if (step === State.Step.Rest) {
+    return 'g-Layout__Page g-Timer g-Timer--Rest'
+  } else {
+    return 'g-Layout__Page g-Timer g-Timer--Prepare'
+  }
+}
+
+function stepCount(state: State.State): string {
+  if (state.step === State.Step.Work || state.step === State.Step.Rest) {
+    return `#${state.tabata.toString()}.${state.cycle.toString()}`
+  } else {
+    return `#${state.tabata.toString()}`
+  }
+}
diff --git a/tsconfig.json b/tsconfig.json
new file mode 100644
index 0000000..3e7f32b
--- /dev/null
+++ b/tsconfig.json
@@ -0,0 +1,13 @@
+{
+  "compilerOptions": {
+    "module": "amd",
+    "target": "es5",
+    "baseUrl": "src",
+    "outFile": "public/main.js",
+    "noImplicitAny": true,
+    "strictNullChecks": true,
+    "removeComments": true,
+    "preserveConstEnums": true
+  },
+  "include": ["src/**/*"]
+}