3 files changed, 263 insertions, 0 deletions
diff --git a/app/components/switch/switch.props.ts b/app/components/switch/switch.props.ts
new file mode 100644
index 0000000..8235457
--- /dev/null
+++ b/app/components/switch/switch.props.ts
@@ -0,0 +1,39 @@
+import { StyleProp, ViewStyle } from "react-native"
+
+export interface SwitchProps {
+  /**
+   * On or off.
+   */
+  value?: boolean
+  /**
+   * Fires when the on/off switch triggers.
+   *
+   * @param newValue The new value we're switching to.
+   */
+  onToggle?: (newValue: boolean) => void
+
+  /**
+   * A style override to apply to the container.  Useful for margins and paddings.
+   */
+  style?: StyleProp<ViewStyle>
+
+  /**
+   * Additional track styling when on.
+   */
+  trackOnStyle?: StyleProp<ViewStyle>
+
+  /**
+   * Additional track styling when off.
+   */
+  trackOffStyle?: StyleProp<ViewStyle>
+
+  /**
+   * Additional thumb styling when on.
+   */
+  thumbOnStyle?: StyleProp<ViewStyle>
+
+  /**
+   * Additional thumb styling when off.
+   */
+  thumbOffStyle?: StyleProp<ViewStyle>
+}
diff --git a/app/components/switch/switch.story.tsx b/app/components/switch/switch.story.tsx
new file mode 100644
index 0000000..998d1df
--- /dev/null
+++ b/app/components/switch/switch.story.tsx
@@ -0,0 +1,110 @@
+/* eslint-disable react-native/no-inline-styles */
+/* eslint-disable react-native/no-color-literals */
+
+import * as React from "react"
+import { View, ViewStyle } from "react-native"
+import { storiesOf } from "@storybook/react-native"
+import { StoryScreen, Story, UseCase } from "../../../storybook/views"
+import { Toggle } from "react-powerplug"
+import { Switch } from "./switch"
+
+declare let module
+
+const styleArray: ViewStyle[] = [{ borderColor: "#686868" }]
+
+const trackOffStyle: ViewStyle[] = [
+  { backgroundColor: "#686868" },
+  {
+    height: 80,
+    borderRadius: 0,
+  },
+]
+const trackOnStyle: ViewStyle[] = [
+  {
+    backgroundColor: "#b1008e",
+    borderColor: "#686868",
+  },
+  {
+    height: 80,
+    borderRadius: 0,
+  },
+]
+const thumbOffStyle: ViewStyle[] = [
+  {
+    backgroundColor: "#b1008e",
+    borderColor: "#686868",
+  },
+  {
+    height: 80,
+    borderRadius: 0,
+  },
+]
+const thumbOnStyle: ViewStyle[] = [
+  { backgroundColor: "#f0c" },
+  {
+    height: 80,
+    borderRadius: 0,
+    borderColor: "#686868",
+  },
+]
+
+storiesOf("Switch", module)
+  .addDecorator((fn) => <StoryScreen>{fn()}</StoryScreen>)
+  .add("Behaviour", () => (
+    <Story>
+      <UseCase text="The Toggle Switch" usage="Use the switch to represent on/off states.">
+        <Toggle initial={false}>
+          {({ on, toggle }) => <Switch value={on} onToggle={toggle} />}
+        </Toggle>
+      </UseCase>
+      <UseCase text="value = true" usage="This is permanently on.">
+        <Switch value={true} />
+      </UseCase>
+      <UseCase text="value = false" usage="This is permanantly off.">
+        <Switch value={false} />
+      </UseCase>
+    </Story>
+  ))
+  .add("Styling", () => (
+    <Story>
+      <UseCase text="Custom Styling" usage="Promise me this won't happen.">
+        <Toggle initial={false}>
+          {({ on, toggle }) => (
+            <View>
+              <Switch
+                trackOnStyle={{ backgroundColor: "green", borderColor: "black" }}
+                trackOffStyle={{ backgroundColor: "red", borderColor: "maroon" }}
+                thumbOnStyle={{ backgroundColor: "cyan" }}
+                thumbOffStyle={{ backgroundColor: "pink" }}
+                value={on}
+                onToggle={toggle}
+              />
+            </View>
+          )}
+        </Toggle>
+      </UseCase>
+
+      <UseCase text="Style array" usage="This either.">
+        <Toggle initial={false}>
+          {({ on, toggle }) => (
+            <View>
+              <Switch
+                style={styleArray}
+                trackOffStyle={trackOffStyle}
+                trackOnStyle={trackOnStyle}
+                thumbOffStyle={thumbOffStyle}
+                thumbOnStyle={thumbOnStyle}
+                // trackOnStyle={{ backgroundColor: "green", borderColor: "black" }}
+                // trackOffStyle={{ backgroundColor: "red", borderColor: "maroon" }}
+                // thumbOnStyle={{ backgroundColor: "cyan" }}
+                // thumbOffStyle={{ backgroundColor: "pink" }}
+
+                value={on}
+                onToggle={toggle}
+              />
+            </View>
+          )}
+        </Toggle>
+      </UseCase>
+    </Story>
+  ))
diff --git a/app/components/switch/switch.tsx b/app/components/switch/switch.tsx
new file mode 100644
index 0000000..0813747
--- /dev/null
+++ b/app/components/switch/switch.tsx
@@ -0,0 +1,114 @@
+import React from "react"
+import { ViewStyle, Animated, Easing, TouchableWithoutFeedback } from "react-native"
+import { color } from "../../theme"
+import { SwitchProps } from "./switch.props"
+
+// dimensions
+const THUMB_SIZE = 30
+const WIDTH = 56
+const MARGIN = 2
+const OFF_POSITION = -0.5
+const ON_POSITION = WIDTH - THUMB_SIZE - MARGIN
+const BORDER_RADIUS = (THUMB_SIZE * 3) / 4
+
+// colors
+const ON_COLOR = color.primary
+const OFF_COLOR = color.palette.offWhite
+const BORDER_ON_COLOR = ON_COLOR
+const BORDER_OFF_COLOR = "rgba(0, 0, 0, 0.1)"
+
+// animation
+const DURATION = 250
+
+// the track always has these props
+const TRACK = {
+  height: THUMB_SIZE + MARGIN,
+  width: WIDTH,
+  borderRadius: BORDER_RADIUS,
+  borderWidth: MARGIN / 2,
+  backgroundColor: color.background,
+}
+
+// the thumb always has these props
+const THUMB: ViewStyle = {
+  position: "absolute",
+  width: THUMB_SIZE,
+  height: THUMB_SIZE,
+  borderColor: BORDER_OFF_COLOR,
+  borderRadius: THUMB_SIZE / 2,
+  borderWidth: MARGIN / 2,
+  backgroundColor: color.background,
+  shadowColor: BORDER_OFF_COLOR,
+  shadowOffset: { width: 1, height: 2 },
+  shadowOpacity: 1,
+  shadowRadius: 2,
+  elevation: 2,
+}
+
+const makeAnimatedValue = (switchOn) => new Animated.Value(switchOn ? 1 : 0)
+
+export function Switch(props: SwitchProps) {
+  const [timer] = React.useState<Animated.Value>(makeAnimatedValue(props.value))
+  const startAnimation = React.useMemo(
+    () => (newValue: boolean) => {
+      const toValue = newValue ? 1 : 0
+      const easing = Easing.out(Easing.circle)
+      Animated.timing(timer, {
+        toValue,
+        duration: DURATION,
+        easing,
+        useNativeDriver: true,
+      }).start()
+    },
+    [timer],
+  )
+
+  const [previousValue, setPreviousValue] = React.useState<boolean>(props.value)
+  React.useEffect(() => {
+    if (props.value !== previousValue) {
+      startAnimation(props.value)
+      setPreviousValue(props.value)
+    }
+  }, [props.value])
+
+  const handlePress = React.useMemo(() => () => props.onToggle && props.onToggle(!props.value), [
+    props.onToggle,
+    props.value,
+  ])
+
+  if (!timer) {
+    return null
+  }
+
+  const translateX = timer.interpolate({
+    inputRange: [0, 1],
+    outputRange: [OFF_POSITION, ON_POSITION],
+  })
+
+  const style = props.style
+
+  const trackStyle = [
+    TRACK,
+    {
+      backgroundColor: props.value ? ON_COLOR : OFF_COLOR,
+      borderColor: props.value ? BORDER_ON_COLOR : BORDER_OFF_COLOR,
+    },
+    props.value ? props.trackOnStyle : props.trackOffStyle,
+  ]
+
+  const thumbStyle = [
+    THUMB,
+    {
+      transform: [{ translateX }],
+    },
+    props.value ? props.thumbOnStyle : props.thumbOffStyle,
+  ]
+
+  return (
+    <TouchableWithoutFeedback onPress={handlePress} style={style}>
+      <Animated.View style={trackStyle}>
+        <Animated.View style={thumbStyle} />
+      </Animated.View>
+    </TouchableWithoutFeedback>
+  )
+}