Add central Widget struct + clean up code

In particular, move all termbox2 usage to TerminalBuffer.zig &
keyboard.zig

Signed-off-by: AnErrupTion <anerruption@disroot.org>

src/tui/components/Label.zig

@@ -0,0 +1,131 @@
+const Label = @This();
+
+const std = @import("std");
+const Allocator = std.mem.Allocator;
+
+const Cell = @import("../Cell.zig");
+const Position = @import("../Position.zig");
+const TerminalBuffer = @import("../TerminalBuffer.zig");
+const Widget = @import("../Widget.zig");
+
+allocator: ?Allocator,
+text: []const u8,
+max_width: ?usize,
+fg: u32,
+bg: u32,
+update_fn: ?*const fn (*Label, *anyopaque) anyerror!void,
+component_pos: Position,
+children_pos: Position,
+
+pub fn init(
+    text: []const u8,
+    max_width: ?usize,
+    fg: u32,
+    bg: u32,
+    update_fn: ?*const fn (*Label, *anyopaque) anyerror!void,
+) Label {
+    return .{
+        .allocator = null,
+        .text = text,
+        .max_width = max_width,
+        .fg = fg,
+        .bg = bg,
+        .update_fn = update_fn,
+        .component_pos = TerminalBuffer.START_POSITION,
+        .children_pos = TerminalBuffer.START_POSITION,
+    };
+}
+
+pub fn deinit(self: *Label) void {
+    if (self.allocator) |allocator| allocator.free(self.text);
+}
+
+pub fn widget(self: *Label) Widget {
+    return Widget.init(
+        self,
+        deinit,
+        null,
+        draw,
+        update,
+        null,
+    );
+}
+
+pub fn setTextAlloc(
+    self: *Label,
+    allocator: Allocator,
+    comptime fmt: []const u8,
+    args: anytype,
+) !void {
+    self.text = try std.fmt.allocPrint(allocator, fmt, args);
+    self.allocator = allocator;
+}
+
+pub fn setTextBuf(
+    self: *Label,
+    buffer: []u8,
+    comptime fmt: []const u8,
+    args: anytype,
+) !void {
+    self.text = try std.fmt.bufPrint(buffer, fmt, args);
+    self.allocator = null;
+}
+
+pub fn setText(self: *Label, text: []const u8) void {
+    self.text = text;
+    self.allocator = null;
+}
+
+pub fn positionX(self: *Label, original_pos: Position) void {
+    self.component_pos = original_pos;
+    self.children_pos = original_pos.addX(TerminalBuffer.strWidth(self.text));
+}
+
+pub fn positionY(self: *Label, original_pos: Position) void {
+    self.component_pos = original_pos;
+    self.children_pos = original_pos.addY(1);
+}
+
+pub fn positionXY(self: *Label, original_pos: Position) void {
+    self.component_pos = original_pos;
+    self.children_pos = Position.init(
+        TerminalBuffer.strWidth(self.text),
+        1,
+    ).add(original_pos);
+}
+
+pub fn childrenPosition(self: Label) Position {
+    return self.children_pos;
+}
+
+pub fn draw(self: *Label) void {
+    if (self.max_width) |width| {
+        TerminalBuffer.drawConfinedText(
+            self.text,
+            self.component_pos.x,
+            self.component_pos.y,
+            width,
+            self.fg,
+            self.bg,
+        );
+        return;
+    }
+
+    TerminalBuffer.drawText(
+        self.text,
+        self.component_pos.x,
+        self.component_pos.y,
+        self.fg,
+        self.bg,
+    );
+}
+
+pub fn update(self: *Label, ctx: *anyopaque) !void {
+    if (self.update_fn) |update_fn| {
+        return @call(
+            .auto,
+            update_fn,
+            .{ self, ctx },
+        );
+    }
+}