make case-insensitivity of regexes optional

HighlightBot/CommandSession.cs

@@ -111,21 +111,42 @@ public async Task ClearHighlights(HighlightCommandContext hcc) {
 	}
 
 	public async Task AddHighlight(HighlightCommandContext hcc, ICollection<string> terms) {
+		static bool IsRegex(string term, out string regex, out string suffix) {
+			if (term.StartsWith("/")) {
+				if (term.EndsWith("/")) {
+					suffix = "";
+					regex = term[1..^1];
+					return true;
+				} else if (term.EndsWith("/c")) {
+					suffix = "c";
+					regex = term[1..^2];
+					return true;
+				}
+			}
+
+			suffix = "";
+			regex = term;
+			return false;
+		}
+
 		HighlightUser user = await GetOrCreateUserAsync(hcc);
 
 		int added = 0;
 		foreach (string term in terms) {
-			string pattern;
 			string display;
-			if (term.StartsWith('/') && term.EndsWith('/')) {
-				pattern = term[1..^1];
-
+			RegexOptions regexOptions = RegexOptions.IgnoreCase;
+
+			if (IsRegex(term, out string pattern, out string suffix)) {
 				if (!Util.IsValidRegex(pattern)) {
 					await hcc.RespondAsync("Invalid regex 🙁");
 					return;
 				}
 
 				display = $"`{term}`";
+
+				if (suffix == "c") {
+					regexOptions = RegexOptions.None;
+				}
 			} else {
 				pattern = $@"\b{Regex.Escape(term.ToLower())}\b";
 
@@ -139,7 +160,8 @@ public async Task AddHighlight(HighlightCommandContext hcc, ICollection<string>
 				added++;
 				user.Terms.Add(new HighlightTerm() {
 					Display = display,
-					Regex = pattern
+					Regex = pattern,
+					RegexOptions = regexOptions,
 				});
 			}
 		}

HighlightBot/Data/HighlightDbContext.cs

@@ -1,3 +1,4 @@
+using System.Text.RegularExpressions;
 using Microsoft.EntityFrameworkCore;
 
 namespace HighlightBot;
@@ -33,5 +34,9 @@ protected override void OnModelCreating(ModelBuilder modelBuilder) {
 		modelBuilder
 			.Entity<HighlightUser>()
 			.HasKey(nameof(HighlightUser.DiscordGuildId), nameof(HighlightUser.DiscordUserId));
+
+		modelBuilder.Entity<HighlightTerm>()
+			.Property(term => term.RegexOptions)
+			.HasDefaultValue(RegexOptions.IgnoreCase);
 	}
 }

HighlightBot/Data/HighlightTerm.cs

@@ -8,4 +8,5 @@ public class HighlightTerm {
 
 	public string Regex { get; set; }
 	public string Display { get; set; }
+	public RegexOptions RegexOptions { get; set; }
 }

HighlightBot/Migrations/20240623171436_RegexOptions.cs

@@ -0,0 +1,26 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace HighlightBot.Migrations
+{
+    public partial class RegexOptions : Migration
+    {
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<int>(
+                name: "RegexOptions",
+                table: "Terms",
+                type: "integer",
+                nullable: false,
+                defaultValue: 1);
+        }
+
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "RegexOptions",
+                table: "Terms");
+        }
+    }
+}

HighlightBot/Migrations/HighlightDbContextModelSnapshot.cs

@@ -36,6 +36,11 @@ protected override void BuildModel(ModelBuilder modelBuilder)
                         .IsRequired()
                         .HasColumnType("text");
 
+                    b.Property<int>("RegexOptions")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("integer")
+                        .HasDefaultValue(1);
+
                     b.Property<decimal>("user_serverid")
                         .HasColumnType("numeric(20,0)");
 

HighlightBot/Program.cs

@@ -176,12 +176,11 @@ private static Task OnMessageCreatedAsync(DiscordClient discord, MessageCreateEv
 								term.User.DiscordUserId,
 								term.User.DiscordGuildId,
 								term.Regex,
-								term.Display
+								term.Display,
+								term.RegexOptions,
 							})
 							.AsEnumerable()
-							// TODO TEMPORARY HACK! this does not scale.
-							// Find a way to get PCRE regexes going in the database (postgres seems to use POSIX regexes)
-							.Where(term => Regex.IsMatch(content, term.Regex, RegexOptions.IgnoreCase))
+							.Where(term => Regex.IsMatch(content, term.Regex, term.RegexOptions))
 							.Select(term => new UserIdAndTerm() {
 								DiscordUserId = term.DiscordUserId,
 								Value = term.Display