feat: add git branch widget

src/tui/status/branch.zig

@@ -0,0 +1,68 @@
+const std = @import("std");
+const tp = @import("thespian");
+const cbor = @import("cbor");
+
+const EventHandler = @import("EventHandler");
+const Plane = @import("renderer").Plane;
+const git = @import("git");
+
+const Widget = @import("../Widget.zig");
+const MessageFilter = @import("../MessageFilter.zig");
+const tui = @import("../tui.zig");
+
+const branch_symbol = "󰘬";
+
+allocator: std.mem.Allocator,
+plane: Plane,
+branch: ?[]const u8 = null,
+
+const Self = @This();
+
+pub fn create(allocator: std.mem.Allocator, parent: Plane, _: ?EventHandler, _: ?[]const u8) @import("widget.zig").CreateError!Widget {
+    const self: *Self = try allocator.create(Self);
+    self.* = .{
+        .allocator = allocator,
+        .plane = try Plane.init(&(Widget.Box{}).opts(@typeName(Self)), parent),
+    };
+    try tui.message_filters().add(MessageFilter.bind(self, receive_git));
+    git.get_current_branch(self.allocator) catch {};
+    return Widget.to(self);
+}
+
+pub fn deinit(self: *Self, allocator: std.mem.Allocator) void {
+    if (self.branch) |p| self.allocator.free(p);
+    self.plane.deinit();
+    allocator.destroy(self);
+}
+
+fn receive_git(self: *Self, _: tp.pid_ref, m: tp.message) MessageFilter.Error!bool {
+    var branch: []const u8 = undefined;
+    if (try cbor.match(m.buf, .{ "git", "current_branch", tp.extract(&branch) })) {
+        if (self.branch) |p| self.allocator.free(p);
+        self.branch = try self.allocator.dupe(u8, branch);
+        return true;
+    }
+    return false;
+}
+
+pub fn layout(self: *Self) Widget.Layout {
+    const branch = self.branch orelse return .{ .static = 0 };
+    var buf: [256]u8 = undefined;
+    var fbs = std.io.fixedBufferStream(&buf);
+    const writer = fbs.writer();
+    writer.print("{s} {s}", .{ branch_symbol, branch }) catch {};
+    const len = self.plane.egc_chunk_width(fbs.getWritten(), 0, 1);
+    return .{ .static = len };
+}
+
+pub fn render(self: *Self, theme: *const Widget.Theme) bool {
+    const branch = self.branch orelse return false;
+    self.plane.set_base_style(theme.editor);
+    self.plane.erase();
+    self.plane.home();
+    self.plane.set_style(theme.statusbar);
+    self.plane.fill(" ");
+    self.plane.home();
+    _ = self.plane.print("{s} {s}", .{ branch_symbol, branch }) catch {};
+    return false;
+}