CommentCreate: handle minimum tips

To avoid calling `setting.Get` excessively, we'll do the following:

(a) Call `setting.Get` once per encountered channel, and stash it.

(b) Before sending **each** comment **with a tip**, call `setting.Get` again to get the latest `min_tip`. Report any over- or under-paid values in the confirmation widget before user hits Send.

(c) For regular comments (no tips), just send as normal based on stashed data from `a`.
    - If `min_tip` was `0` but creator later changed to non-zero, Commentron would trigger an error anyway, and the app can get the latest `min_tip` amount to inform the user.
    - If `min_tip` was not `0` but creator later changed to `0`, the app would be incorrectly forcing the user to pay based on the old amount from `a`.  But when he hits `b`, he now knows he has overpaid, and can still cancel.

ui/component/commentCreate/view.jsx

@@ -15,6 +15,7 @@ import WalletTipAmountSelector from 'component/walletTipAmountSelector';
 import CreditAmount from 'component/common/credit-amount';
 import ChannelThumbnail from 'component/channelThumbnail';
 import UriIndicator from 'component/uriIndicator';
+import I18nMessage from 'component/i18nMessage';
 import Empty from 'component/common/empty';
 import { Lbryio } from 'lbryinc';
 import { getChannelIdFromClaim } from 'util/claim';
@@ -97,6 +98,17 @@ export function CommentCreate(props: Props) {
   const [shouldDisableReviewButton, setShouldDisableReviewButton] = React.useState();
   const channelId = getChannelIdFromClaim(claim);
   const channelSettings = channelId ? settingsByChannelId[channelId] : undefined;
+  const minTip = (channelSettings && channelSettings.min_tip_amount_comment) || 0;
+  const minTipMet = minTip === 0 || tipAmount >= minTip;
+
+  const MinTipNotice =
+    minTip !== 0 ? (
+      <div className="help--notice">
+        <I18nMessage tokens={{ lbc: <CreditAmount noFormat amount={minTip} /> }}>
+          This channel requires a minimum tip of %lbc% to post a comment.
+        </I18nMessage>
+      </div>
+    ) : null;
 
   function handleCommentChange(event) {
     let commentValue;
@@ -125,6 +137,14 @@ export function CommentCreate(props: Props) {
     window.removeEventListener('keydown', altEnterListener);
   }
 
+  function handleReview() {
+    if (channelId) {
+      // Get the latest minTip value for final review.
+      doFetchCreatorSettings(channelId);
+    }
+    setIsReviewingSupportComment(true);
+  }
+
   function handleSubmit() {
     if (activeChannelClaim && commentValue.length) {
       handleCreateComment();
@@ -238,7 +258,7 @@ export function CommentCreate(props: Props) {
   }
 
   /**
-   *
+   * handleCreateComment
    * @param {string} [txid] Optional transaction id generated by
    * @param {string} [payment_intent_id] Optional payment_intent_id from Stripe payment
    * @param {string} [environment] Optional environment for Stripe (test|live)
@@ -271,6 +291,7 @@ export function CommentCreate(props: Props) {
     setAdvancedEditor(!advancedEditor);
   }
 
+  // Fetch channel constraints if not already.
   React.useEffect(() => {
     if (!channelSettings && channelId) {
       doFetchCreatorSettings(channelId);
@@ -333,7 +354,7 @@ export function CommentCreate(props: Props) {
           <Button
             autoFocus
             button="primary"
-            disabled={disabled}
+            disabled={disabled || !minTipMet}
             label={
               isSubmitting
                 ? __('Sending...')
@@ -344,6 +365,7 @@ export function CommentCreate(props: Props) {
             onClick={handleSupportComment}
           />
           <Button button="link" label={__('Cancel')} onClick={() => setIsReviewingSupportComment(false)} />
+          {MinTipNotice}
         </div>
       </div>
     );
@@ -397,34 +419,36 @@ export function CommentCreate(props: Props) {
         {isSupportComment ? (
           <>
             <Button
-              disabled={disabled || tipError || shouldDisableReviewButton}
+              disabled={disabled || tipError || shouldDisableReviewButton || !minTipMet}
               type="button"
               button="primary"
               icon={activeTab === TAB_LBC ? ICONS.LBC : ICONS.FINANCE}
               label={__('Review')}
-              onClick={() => setIsReviewingSupportComment(true)}
+              onClick={handleReview}
             />
 
             <Button disabled={disabled} button="link" label={__('Cancel')} onClick={() => setIsSupportComment(false)} />
           </>
         ) : (
           <>
-            <Button
-              ref={buttonRef}
-              button="primary"
-              disabled={disabled}
-              type="submit"
-              label={
-                isReply
-                  ? isSubmitting
-                    ? __('Replying...')
-                    : __('Reply')
-                  : isSubmitting
-                  ? __('Commenting...')
-                  : __('Comment --[button to submit something]--')
-              }
-              requiresAuth={IS_WEB}
-            />
+            {minTip === 0 && (
+              <Button
+                ref={buttonRef}
+                button="primary"
+                disabled={disabled}
+                type="submit"
+                label={
+                  isReply
+                    ? isSubmitting
+                      ? __('Replying...')
+                      : __('Reply')
+                    : isSubmitting
+                    ? __('Commenting...')
+                    : __('Comment --[button to submit something]--')
+                }
+                requiresAuth={IS_WEB}
+              />
+            )}
             {!claimIsMine && (
               <Button
                 disabled={disabled}
@@ -449,7 +473,7 @@ export function CommentCreate(props: Props) {
                 }}
               />
             )}
-            {isReply && (
+            {isReply && minTip === 0 && (
               <Button
                 button="link"
                 label={__('Cancel')}
@@ -462,6 +486,7 @@ export function CommentCreate(props: Props) {
             )}
           </>
         )}
+        {MinTipNotice}
       </div>
     </Form>
   );