From cbe86f548ad78d281f59bc505aa43fcbd30c3c77 Mon Sep 17 00:00:00 2001
From: Jon Drews <jon@jondrews.com>
Date: Mon, 13 Feb 2023 23:50:51 -0500
Subject: [PATCH] implement pausing of log tailing when use scrolls up

---
 web/src/LogStationLogViewer.jsx | 71 ++++++++++++++++++++++++++++-----
 web/src/MainLayout.jsx          |  9 +----
 2 files changed, 63 insertions(+), 17 deletions(-)

diff --git a/web/src/LogStationLogViewer.jsx b/web/src/LogStationLogViewer.jsx
index b3d6fe7..84bcacb 100644
--- a/web/src/LogStationLogViewer.jsx
+++ b/web/src/LogStationLogViewer.jsx
@@ -1,10 +1,55 @@
 import React from 'react';
 import {LogViewer, LogViewerSearch} from '@patternfly/react-log-viewer';
-import { Toolbar, ToolbarContent, ToolbarItem } from '@patternfly/react-core';
+import {Button, Toolbar, ToolbarContent, ToolbarItem} from '@patternfly/react-core';
 import "@patternfly/react-core/dist/styles/base.css";
+import OutlinedPlayCircleIcon from "@patternfly/react-icons/dist/esm/icons/outlined-play-circle-icon";
 
 const LogStationLogViewer = (props) => {
 
+    // isPaused: control for whether a user has scrolled up (paused)
+    // this isPaused effectively stops the webapp from pinning to the bottom of the log
+    const [isPaused, setIsPaused] = React.useState(false);
+
+    // selectedScrollToRow: the row in the log that the LogViewer should scroll to (via prop scrollToRow)
+    // when set to undefined, the scrollToRow prop will do nothing
+    const [selectedScrollToRow, setSelectedScrollToRow] = React.useState(undefined)
+
+    // reference for the LogViewer component
+    const logViewerRef = React.useRef();
+
+    React.useEffect(() => {
+        if (!isPaused) {
+            if (logViewerRef && logViewerRef.current) {
+                setSelectedScrollToRow(props.data.length) // scroll down to the end of the log file
+            }
+        }
+    }, [isPaused, props.data.length]);
+
+    const onScroll = ({ scrollOffsetToBottom, _scrollDirection, scrollUpdateWasRequested }) => {
+        if (!scrollUpdateWasRequested) {
+            if (scrollOffsetToBottom > 0) { // if we're not at the bottom
+                setIsPaused(true); // pause log
+                setSelectedScrollToRow(undefined) // stop the pinning/tailing to the bottom via prop scrollToRow
+            } else {
+                setIsPaused(false); // tail the log (pin to the bottom of log)
+            }
+        }
+    };
+
+    // shows a button on the bottom that lets you resume tailing the log if you scrolled up / paused
+    const FooterButton = () => {
+        const handleClick = _e => {
+            setIsPaused(false);
+        };
+        return (
+            <Button onClick={handleClick} isBlock>
+                <OutlinedPlayCircleIcon />
+                resume
+                {/*resume {linesBehind === 0 ? null : `and show ${linesBehind} lines`}*/}
+            </Button>
+        );
+    };
+
     return (
         <LogViewer hasLineNumbers={false}
                    height={'100%'}
@@ -12,15 +57,21 @@ const LogStationLogViewer = (props) => {
                    data={props.data}
                    theme={'dark'}
                    isTextWrapped={true}
-                   toolbar={
-                       <Toolbar>
-                           <ToolbarContent>
-                               <ToolbarItem>
-                                   <LogViewerSearch minSearchChars={2} placeholder={"         search"}/>
-                               </ToolbarItem>
-                           </ToolbarContent>
-                       </Toolbar>
-                   }/>
+                   innerRef={logViewerRef}
+                   scrollToRow={selectedScrollToRow}
+                   onScroll={onScroll}
+                   footer={isPaused && <FooterButton />}
+                   //TODO: disabled search for now. Will come back to it.
+                   // toolbar={
+                   //     <Toolbar>
+                   //         <ToolbarContent>
+                   //             <ToolbarItem>
+                   //                 <LogViewerSearch minSearchChars={2} placeholder={"         search"}/>
+                   //             </ToolbarItem>
+                   //         </ToolbarContent>
+                   //     </Toolbar>
+                   // }
+        />
     );
 };
 
diff --git a/web/src/MainLayout.jsx b/web/src/MainLayout.jsx
index 1191bb3..90cd2ab 100644
--- a/web/src/MainLayout.jsx
+++ b/web/src/MainLayout.jsx
@@ -21,14 +21,10 @@ const MainLayout = (props) => {
         setSelectedLogFile(newLogFile);
     };
 
-    //TODO: Figure out how to wrap this in a tabular header that shows the file and lets you swap between files
-        // Might be able to have this react class be instantiated within a larger react class that handles the file tabs and switching
     return (
         <Container disableGutters maxWidth="false" sx={{width: '100%', height: '100vh'}}>
                 <Box sx={{borderBottom: 1, borderColor: 'divider', height: '8vh', m: 0, p: 0}}>
                     <Tabs value={selectedLogFile} aria-label="log selector bar" textColor="secondary" indicatorColor="secondary" onChange={handleLogSelection}>
-                        {/*<Tabs value={value} onChange={handleChange} aria-label="basic tabs example">*/
-                            /*TODO: use value and onChange to populate tabs dynamically and make them do stuff*/}
                         <Tab key="0" value="0" label="logstation" disabled={true} disableRipple={true} {...a11yProps("0")}
                              sx={{
                                  color: '#ffffff !important',
@@ -40,11 +36,10 @@ const MainLayout = (props) => {
                         {[...props.logFiles.keys()].map(logFile =>
                             (<Tab key={logFile} value={logFile} label={logFile} {...a11yProps(logFile)} sx={{color: '#ffffff', background: '#222', textTransform: 'unset'}}/>)
                         )}
-
                     </Tabs>
                 </Box>
-                <Box sx={{width: '100%', height: '92vh'}} className="LogViewer">
-                       <LogStationLogViewer data={props.logFiles.get(selectedLogFile)}/>
+                <Box sx={{width: '100%', height: '92vh'}} className="LogViewerBox">
+                       <LogStationLogViewer data={props.logFiles.get(selectedLogFile) ?? []}/>
                 </Box>
         </Container>
     );