From e4a7df3fd9e2d88457103c1d7688004aabed662b Mon Sep 17 00:00:00 2001
From: Raymond Hill <rhill@raymondhill.net>
Date: Sun, 19 Dec 2021 08:17:06 -0500
Subject: [PATCH] Improve auto-completion in _"My filters"_ editor

---
 src/js/codemirror/ubo-static-filtering.js | 98 +++++++++++++++++++----
 1 file changed, 82 insertions(+), 16 deletions(-)

diff --git a/src/js/codemirror/ubo-static-filtering.js b/src/js/codemirror/ubo-static-filtering.js
index 06bb01e6b..3552d6f80 100644
--- a/src/js/codemirror/ubo-static-filtering.js
+++ b/src/js/codemirror/ubo-static-filtering.js
@@ -443,23 +443,89 @@ const initHints = function() {
             if ( text.startsWith(seed) === false ) { continue; }
             out.push(hint);
         }
-        // If no match, try again with a different heuristic
-        if ( out.length === 0 ) {
-            for ( const hint of hints ) {
-                const text = hint instanceof Object
-                    ? hint.displayText || hint.text
-                    : hint;
-                if ( seedLeft.length === 1 ) {
-                    if ( text.startsWith(seedLeft) === false ) { continue; }
-                } else if ( text.includes(seed) === false ) { continue; }
-                out.push(hint);
-            }
+        if ( out.length !== 0 ) {
+            return {
+                from: { line: cursor.line, ch: cursor.ch - seedLeft.length },
+                to: { line: cursor.line, ch: cursor.ch + seedRight.length },
+                list: out,
+            };
+        }
+        // If no match, try again with a different heuristic: valid hints are
+        // those matching left seed, not matching right seed but right seed is
+        // found to be a valid hint. This is to take care of cases like:
+        //
+        //     *$script,redomain=example.org
+        //                ^
+        //                + cursor position
+        //
+        // In such case, [ redirect=, redirect-rule= ] should be returned
+        // as valid hints.
+        for ( const hint of hints ) {
+            const text = hint instanceof Object
+                ? hint.displayText || hint.text
+                : hint;
+            if ( seedLeft.length === 0 ) { continue; }
+            if ( text.startsWith(seedLeft) === false ) { continue; }
+            if ( hints.includes(seedRight) === false ) { continue; }
+            out.push(hint);
+        }
+        if ( out.length !== 0 ) {
+            return {
+                from: { line: cursor.line, ch: cursor.ch - seedLeft.length },
+                to: { line: cursor.line, ch: cursor.ch },
+                list: out,
+            };
+        }
+        // If no match, try again with a different heuristic: valid hints are
+        // those containing seed as a substring. This is to take care of cases
+        // like:
+        //
+        //     *$script,redirect=gif
+        //                       ^
+        //                       + cursor position
+        //
+        // In such case, [ 1x1.gif, 1x1-transparent.gif ] should be returned
+        // as valid hints.
+        for ( const hint of hints ) {
+            const text = hint instanceof Object
+                ? hint.displayText || hint.text
+                : hint;
+            if ( seedLeft.length === 1 ) {
+                if ( text.startsWith(seedLeft) === false ) { continue; }
+            } else if ( text.includes(seed) === false ) { continue; }
+            out.push(hint);
+        }
+        if ( out.length !== 0 ) {
+            return {
+                from: { line: cursor.line, ch: cursor.ch - seedLeft.length },
+                to: { line: cursor.line, ch: cursor.ch + seedRight.length },
+                list: out,
+            };
+        }
+        // If still no match, try again with a different heuristic: valid hints
+        // are those containing left seed as a substring. This is to take care
+        // of cases like:
+        //
+        //     *$script,redirect=gifdomain=example.org
+        //                          ^
+        //                          + cursor position
+        //
+        // In such case, [ 1x1.gif, 1x1-transparent.gif ] should be returned
+        // as valid hints.
+        for ( const hint of hints ) {
+            const text = hint instanceof Object
+                ? hint.displayText || hint.text
+                : hint;
+            if ( text.includes(seedLeft) === false ) { continue; }
+            out.push(hint);
+        }
+        if ( out.length !== 0 ) {
+            return {
+                from: { line: cursor.line, ch: cursor.ch - seedLeft.length },
+                to: { line: cursor.line, ch: cursor.ch },
+                list: out,
+            };
         }
-        return {
-            from: { line: cursor.line, ch: cursor.ch - seedLeft.length },
-            to: { line: cursor.line, ch: cursor.ch + seedRight.length },
-            list: out,
-        };
     };
 
     const getOriginHints = function(cursor, line, suffix = '') {