docs(blade): Toast API decisions (#1990)

packages/blade/src/components/Toast/_decisions/decisions.md

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+# Toast 🏷️
+
+Toasts are used to provide feedback to the user after an important action has been performed. 
+Toasts can also be used to provide feedback to the user when a system event occurs, such as when a file is saved.
+
+<img width="426" alt="image" src="./toast-thumbnail.png" />
+
+## Design
+
+- [Toast - Figma Design](https://www.figma.com/file/jubmQL9Z8V7881ayUD95ps/Blade-DSL?type=design&node-id=7665-27414&mode=design&t=UNInCMmP1iFCu9je-0)
+
+## Features
+
+- Stackable
+- Auto dismissable / manual dismissable
+- `informational` or `promotional` types
+
+## Anatomy
+
+### Informational Toast
+
+<img src="./toast-anatomy.png" width="100%" alt="Toast anatomy" />
+
+### Promotional Toast
+
+<img src="./example-promotional-toast.png" width="380" alt="Promotional toast example" />
+
+## Simple Usage
+
+The blade toasts will use [react-hot-toast](https://react-hot-toast.com/) under the hood with a similar imperative API to show, dismiss and create new toasts without needing for consumer to handle positional or stacking logic. 
+
+```jsx
+import { BladeProvider, ToastContainer, useToast } from "@razorpay/blade/components"
+
+const HomePage = () => {
+  const toast = useToast();
+
+  return (
+    <Button
+      onClick={() => {
+        toast.show({
+          type: 'informational',
+          color: 'success',
+          content: 'Payment Successful',
+          leading: <DollarIcon />,
+          autoDismiss: true,
+          onDismissButtonClick: () => {
+            console.log('Toast dismissed');
+          },
+          action: {
+            text: 'View',
+            onClick: () => {
+              console.log('Toast action clicked');
+            }
+          }
+        });
+      }}
+    >
+      Show Toast
+    </Button>
+  );
+};
+
+const App = () => {
+  return (
+    <BladeProvider>
+      <ToastContainer position="bottom-left" />
+      <HomePage />
+    </BladeProvider>
+  )
+}
+```
+
+## Props
+
+```ts
+type ToastProps = {
+  /**
+   * @default `informational`
+   */
+  type?: 'informational' | 'promotional';
+
+  /**
+   * @default `neutral`
+   */
+  color?: 'neutral' | 'positive' | 'negative' | 'warning' | 'information'
+
+  /**
+   * Content of the toast
+   */
+  content: React.ReactNode;
+
+  /**
+   * Can be used to render an icon or asset
+   */
+  leading?: React.ReactElement;
+
+  /**
+   * If true, the toast will be dismissed after few seconds
+   * 
+   * @default true - for informational toast
+   * @default false - for promotional toast
+   */
+  autoDismiss?: boolean;
+
+  /**
+   * Duration after which the toast will be dismissed (in ms)
+   * 
+   * Duration for promotional toast is 8s
+   * Duration for informational toast is 4s
+   */
+  duration?: 8000 | 4000;
+
+  /**
+   * Called when the toast is dismissed or duration runs out
+   */
+  onDismissButtonClick?: () => void;
+
+  /**
+   * Primary action of toast
+   */
+  action?: {
+    text: string;
+    onClick?: (e: Event) => void;
+    isLoading? boolean;
+  }
+
+  /**
+   * Forwarded to react-hot-toast
+   * 
+   * This can be used to programatically update toasts by providing an id
+   */
+  toastId?: string; 
+}
+```
+
+### useToast
+
+The useToast hook will return few modified methods from [react-hot-toast](https://react-hot-toast.com/docs/toast): 
+
+```ts
+type useToastReturnType = {
+  /**
+   * @returns id of the toast
+   */
+  show: (toast: Toast) => string;
+
+  /**
+   * id of the toast to be dismissed
+   * 
+   * if id is not provided, all the toasts will be dismissed
+   */
+  dismiss: (toastId?: string) => void;
+}
+```
+
+## Examples
+
+#### Removing a toast
+
+react-hot-toast provides this functionality, for more info see [react-hot-toast docs](https://react-hot-toast.com/docs/toast#dismiss-toast-programmatically)
+
+```jsx
+import { BladeProvider, ToastContainer, useToast } from "@razorpay/blade/components"
+
+const Example = () => {
+  const toastId = React.useRef(null);
+  const toast = useToast();
+
+  return (
+    <Box>
+      <Button
+        onClick={() => {
+          toastId.current = toast.show({
+            color: 'success',
+            content: 'Payment Successful',
+          });
+        }}
+      >
+        Show Toast
+      </Button>
+      <Button onClick={() => toast.dismiss(toastId.current)}>Dismiss Toast</Button>
+    </Box>
+  );
+};
+```
+
+### Promotional Toast
+
+```jsx
+import { BladeProvider, ToastContainer, useToast } from "@razorpay/blade/components"
+
+const Example = () => {
+  const toast = useToast();
+
+  return (
+    <Button
+      onClick={() => {
+        toast.show({
+          type: 'promotional',
+          content: (
+            <Box>
+              <Heading>Payment Successful</Heading>
+              <Text>Amount: ₹100</Text>
+            </Box>
+          ),
+          leading: <DollarIcon />,
+          action: {
+            text: 'Okay'
+          }
+        });
+      }}
+    >
+      Do payment
+    </Button>
+  );
+};
+```
+
+<img src="./example-promotional-toast.png" width="380" alt="Promotional toast example" />
+
+
+## Motion
+
+You can checkout the toast motion [here](https://www.figma.com/proto/jubmQL9Z8V7881ayUD95ps/Blade-DSL?type=design&node-id=75848-1063056&t=QZkki0ZrlcG4sKzw-0&scaling=min-zoom&page-id=7665%3A27414).
+
+## Accessibility
+
+- Toast components will follow the WAI-ARIA guidelines for [alert](https://www.w3.org/WAI/ARIA/apg/patterns/alert/examples/alert/). For error toast we will use the `alert` role and for informational toast we will use the `status` role.
+
+
+## References
+
+- https://react-hot-toast.com/docs
+- https://chakra-ui.com/docs/components/toast/usage
+
+## Open Questions
+
+- Q. What should be the default duration for auto dismissable toasts?
+  - A. 4s for informational toasts and 8s for promotional toasts
+
+- Q. Should we call it `onDismissButtonClick` or `onDismiss`? 
+
+- Q. Should the dismiss handler be called even when the toast is auto dismissed? Or should we have different handlers for auto dismiss and manual dismiss? (eg: `onAutoDismiss` `onDismissButtonClick`)
+  - A. We will call it `onDismissButtonClick` and it will only be called when the user clicks on the dismiss button.
+
+- Q. In the `useToast` hook should we call the returned functions `showToast`/`dismissToast` or `show`/`dismiss`?
+
+  If we call them `show` & `dismiss` consumer can do this and might look more cleaner:
+
+  ```jsx
+  const App = () => {
+    const toast = useToast();
+
+    toast.show(); // <-- they will also get auto complete when writing `toast.`
+    toast.dismiss();
+  }
+  ```
+  - A. We will call them `show` & `dismiss`
+
+- Q. In design we are restricting the Toast position to be bottom-left. In that case should we also do the same or should we allow all the positions & set the default to bottom-left? (If we allow all the positions, we will have to add some additional logic to handle stacking/animation of toasts coming from top instead of bottom)
+  - A. We will only allow bottom-left position for now.
+
+- Q. Should we keep the ToastContainer inside BladeProvider? 
+
+  The problem is if we keep it inside BladeProvider, given our new light/dark mode setup where consumers will need to nest BladeProviders it would cause ToastContainer to render [multiple times](https://github.com/razorpay/blade/pull/1990#discussion_r1470796627).
+  - A. We will expose ToastContainer, so that users can render it at the root level of their app regardless of where BladeProvider is.