use domain::{
    AlignItems, ContainerNode, Direction, JustifyContent, Layout, LayoutChild, LayoutNode,
    LayoutValidationError, Sizing, WidgetId,
};
use std::collections::BTreeSet;

fn leaf(id: WidgetId) -> LayoutChild {
    LayoutChild {
        sizing: Sizing::Flex(1),
        node: LayoutNode::Leaf(id),
    }
}

fn row(children: Vec<LayoutChild>) -> LayoutNode {
    LayoutNode::Container(ContainerNode {
        direction: Direction::Row,
        gap: 0,
        padding: 0,
        justify_content: JustifyContent::Start,
        align_items: AlignItems::Stretch,
        children,
    })
}

#[test]
fn validate_returns_empty_when_all_widgets_exist() {
    let layout = Layout {
        root: row(vec![leaf(1), leaf(2)]),
    };
    let known = BTreeSet::from([1, 2]);
    assert!(layout.validate(&known).is_empty());
}

#[test]
fn validate_reports_unknown_widget_ids() {
    let layout = Layout {
        root: row(vec![leaf(1), leaf(99)]),
    };
    let known = BTreeSet::from([1]);
    let errors = layout.validate(&known);
    assert_eq!(errors, vec![LayoutValidationError::UnknownWidget(99)]);
}

#[test]
fn validate_reports_empty_container() {
    let layout = Layout { root: row(vec![]) };
    let known = BTreeSet::new();
    let errors = layout.validate(&known);
    assert_eq!(errors, vec![LayoutValidationError::EmptyContainer]);
}

#[test]
fn validate_checks_nested_containers() {
    let inner = LayoutChild {
        sizing: Sizing::Flex(1),
        node: row(vec![leaf(1), leaf(42)]),
    };
    let layout = Layout {
        root: row(vec![inner, leaf(2)]),
    };
    let known = BTreeSet::from([1, 2]);
    let errors = layout.validate(&known);
    assert_eq!(errors, vec![LayoutValidationError::UnknownWidget(42)]);
}

#[test]
fn widget_ids_collects_all_leaf_ids() {
    let inner = LayoutChild {
        sizing: Sizing::Flex(1),
        node: row(vec![leaf(3)]),
    };
    let layout = Layout {
        root: row(vec![leaf(1), inner, leaf(2)]),
    };
    assert_eq!(layout.widget_ids(), BTreeSet::from([1, 2, 3]));
}