const std = @import("std");
const terminal = @import("../terminal.zig");

const isTaggedUnion = @import("../event.zig").isTaggedUnion;
const Error = @import("../event.zig").Error;

const log = std.log.scoped(.widget_spacer);

pub fn Widget(comptime Event: type, comptime Renderer: type) type {
    if (!isTaggedUnion(Event)) {
        @compileError("Provided user event `Event` for `Layout(comptime Event: type)` is not of type `union(enum)`.");
    }
    return struct {
        allocator: std.mem.Allocator,
        size: terminal.Size,
        size_changed: bool,

        pub fn init(allocator: std.mem.Allocator) *@This() {
            var this = allocator.create(@This()) catch @panic("Space.zig: Failed to create.");
            this.allocator = allocator;
            this.size_changed = true;
            return this;
        }

        pub fn deinit(this: *@This()) void {
            this.allocator.destroy(this);
        }

        pub fn handle(this: *@This(), event: Event) ?Event {
            switch (event) {
                .resize => |size| {
                    this.size = size;
                    this.size_changed = true;
                },
                else => {},
            }
            return null;
        }

        pub fn render(this: *@This(), renderer: *Renderer) !void {
            if (this.size_changed) {
                try renderer.clear(this.size);
                this.size_changed = false;
            }
        }
    };
}