chore: implement initial bot with substitute command

This commit introduces a Bot struct which is the main type of this
project. The Bot holds a backlog of messages to be able to update a
typo in a message and so on.

So far there is no IRC/TLS implementation, it is only the base logic.

src/main.zig

@@ -3,25 +3,26 @@ const zigeru = @import("zigeru");
 
 pub fn main() !void {
     // Prints to stderr, ignoring potential errors.
-    std.debug.print("All your {s} are belong to us.\n", .{"codebase"});
-    try zigeru.bufferedPrint();
-}
-
-test "simple test" {
-    const gpa = std.testing.allocator;
-    var list: std.ArrayList(i32) = .empty;
-    defer list.deinit(gpa); // Try commenting this out and see if zig detects the memory leak!
-    try list.append(gpa, 42);
-    try std.testing.expectEqual(@as(i32, 42), list.pop());
-}
-
-test "fuzz example" {
-    const Context = struct {
-        fn testOne(context: @This(), input: []const u8) anyerror!void {
-            _ = context;
-            // Try passing `--fuzz` to `zig build test` and see if it manages to fail this test case!
-            try std.testing.expect(!std.mem.eql(u8, "canyoufindme", input));
-        }
+    const message = zigeru.bot.Message{
+        .author = "Jassob",
+        .timestamp = 12345,
+        .content = "All your base are belong to us.\n",
     };
-    try std.testing.fuzz(Context{}, Context.testOne, .{});
+
+    var gpa = std.heap.DebugAllocator(.{}){};
+    var bot = zigeru.bot.Bot.new(gpa.allocator());
+    bot.hear(message);
+    const command = zigeru.bot.Command{
+        .substitute = .{
+            .author = "Jassob",
+            .needle = "base",
+            .replacement = "codebase",
+        },
+    };
+    const result = try bot.execute(&command);
+    switch (result) {
+        .post_message => |msg| {
+            std.debug.print("{s}", .{msg.content});
+        },
+    }
 }