/// TODO:
/// * Text box w/ "reset" button
/// * Generic Minimize/Close Components
/// * Title bar w/ min/close controls
/// * Notice/Warning/Error Popups
/// * Textbox (ReadOnly)
/// * Textbox (ReadWrite)
/// * Move code to submodules
///
use bevy::{
    asset::Asset,
    input::mouse::{MouseScrollUnit, MouseWheel},
    prelude::*,
    window::PrimaryWindow,
};
use std::cmp::PartialEq;

#[derive(Debug, Component, PartialEq)]
pub struct TargetAsset<T: Asset> {
    pub handle: Handle<T>,
}

#[derive(Debug, Component, PartialEq)]
pub struct TargetEntity {
    pub entity: Entity,
}

pub struct GameUiPlugin;

impl Plugin for GameUiPlugin {
    fn build(&self, app: &mut App) {
        app.add_systems(
            Update,
            (
                init_titles,
                manage_button_interaction,
                manage_select_active,
                manage_cursor,
                manage_scroll,
                manage_collapse_active,
                manage_collapse_hiding,
                show_child_number,
                manage_sort,
            ),
        );
    }
}

pub use title::*;
mod title {
    use super::*;

    #[derive(Debug, Component, Default)]
    pub struct Title {
        pub name: String,
        pub note: Option<String>,
    }

    pub fn init_titles(
        events: Query<(Entity, &Title), Or<(Changed<Title>, Added<Title>)>>,
        mut commands: Commands,
    ) {
        events.for_each(|(entity, Title { name, note })| {
            commands
                .entity(entity)
                .despawn_descendants()
                .with_children(|parent| {
                    parent
                        .spawn((
                            NodeBundle {
                                style: Style {
                                    padding: UiRect::all(Val::Px(5.0)),
                                    margin: UiRect::all(Val::Px(5.0)),
                                    border: UiRect::all(Val::Px(1.0)),
                                    flex_direction: FlexDirection::Row,
                                    ..default()
                                },
                                ..default()
                            },
                            Sorting(0),
                        ))
                        .with_children(|parent| {
                            parent.spawn(TextBundle {
                                text: Text {
                                    sections: vec![
                                        TextSection {
                                            value: name.clone(),
                                            style: TextStyle {
                                                color: Color::BLACK,
                                                ..default()
                                            },
                                        },
                                        TextSection {
                                            value: note.clone().unwrap_or(String::new()),
                                            style: TextStyle {
                                                color: Color::BLACK,
                                                ..default()
                                            },
                                        },
                                    ],
                                    ..default()
                                },
                                style: Style {
                                    margin: UiRect::all(Val::Px(5.0)),
                                    padding: UiRect::all(Val::Px(5.0)),
                                    ..default()
                                },
                                ..default()
                            });
                        });
                });
        });
    }
}

pub use collapse::*;
mod collapse {
    use super::*;

    #[derive(Debug, Component)]
    pub struct Collapse {
        pub target: Entity,
    }

    pub fn manage_collapse_active(
        events: Query<
            (Entity, Option<&Active>, &Interaction),
            (Changed<Interaction>, With<Button>, With<Collapse>),
        >,
        mut commands: Commands,
    ) {
        events
            .iter()
            .filter(|(_, _, &interaction)| interaction == Interaction::Pressed)
            .for_each(|(entity, active, _)| {
                match active {
                    Some(_) => {
                        commands.entity(entity).remove::<Active>();
                    }
                    None => {
                        // Set this butotn to active
                        commands.entity(entity).insert(Active);
                    }
                };
            });
    }

    pub fn manage_collapse_hiding(
        added: Query<Entity, (Added<Active>, With<Collapse>)>,
        mut removed: RemovedComponents<Active>,
        collapses: Query<&Collapse, With<Button>>,
        mut styles: Query<&mut Style>,
    ) {
        // Added collapse, display the target entity
        added.iter().for_each(|e| {
            if let Ok(Collapse { target }) = collapses.get(e) {
                if let Ok(mut style) = styles.get_mut(*target) {
                    style.display = Display::Flex;
                }
            }
        });
        // Removed collapse, hide the target entity
        removed.iter().for_each(|e| {
            if let Ok(Collapse { target }) = collapses.get(e) {
                if let Ok(mut style) = styles.get_mut(*target) {
                    style.display = Display::None;
                }
            }
        });
    }

    pub fn show_child_number(
        events: Query<(Entity, &Children), (Changed<Children>, With<Node>)>,
        mut tabs: Query<(&Collapse, &mut Title)>,
    ) {
        // Any time a widget changes
        events.iter().for_each(|(entity, children)| {
            // Find any tabs which have this as a target
            tabs.iter_mut()
                .find_map(|(collapse, title)| {
                    if entity == collapse.target {
                        Some(title)
                    } else {
                        None
                    }
                })
                .iter_mut()
                .for_each(|title| {
                    title.note = Some(format!("({})", children.len().saturating_sub(1)))
                });
        });
    }
}

pub use buttons::*;
mod buttons {
    use super::*;

    #[derive(Debug, Component)]
    pub struct Active;

    pub fn manage_button_interaction(
        events: Query<
            (Entity, &Interaction, Option<&Active>),
            (Changed<Interaction>, With<Button>),
        >,
        added_active: Query<Entity, Added<Active>>,
        mut removed_active: RemovedComponents<Active>,
        mut bg_colors: Query<&mut BackgroundColor>,
    ) {
        added_active.for_each(|e| {
            if let Ok(mut bg_color) = bg_colors.get_mut(e) {
                *bg_color = Color::ORANGE.into();
            }
        });
        removed_active.iter().for_each(|e| {
            if let Ok(mut bg_color) = bg_colors.get_mut(e) {
                *bg_color = Color::WHITE.into();
            }
        });
        events.for_each(|(entity, interaction, active)| {
            if let Ok(mut bg_color) = bg_colors.get_mut(entity) {
                match active {
                    Some(_) => match interaction {
                        Interaction::None => *bg_color = Color::ORANGE.into(),
                        Interaction::Pressed => *bg_color = Color::YELLOW.into(),
                        Interaction::Hovered => *bg_color = Color::RED.into(),
                    },
                    None => match interaction {
                        Interaction::None => *bg_color = Color::WHITE.into(),
                        Interaction::Pressed => *bg_color = Color::WHITE.into(),
                        Interaction::Hovered => *bg_color = Color::GRAY.into(),
                    },
                }
            }
        })
    }

    /// Marks a container node as having single- or multi-active components
    #[derive(Debug, Component)]
    pub enum Select {
        Multi,
        Single,
    }

    pub fn manage_select_active(
        events: Query<(Entity, &Parent), Added<Active>>,
        children: Query<(&Select, &Children)>,
        mut commands: Commands,
    ) {
        events.iter().for_each(|(entity, parent)| {
            if let Ok((select, childs)) = children.get(parent.get()) {
                match select {
                    Select::Single => {
                        childs
                            .iter()
                            .filter(|&child| *child != entity)
                            .for_each(|&child| {
                                commands.entity(child).remove::<Active>();
                            })
                    }
                    Select::Multi => (),
                }
            }
        });
    }
}

pub use scroll::*;
mod scroll {
    use super::*;

    #[derive(Debug, Component)]
    pub struct Scroll;

    pub fn manage_scroll(
        mut events: EventReader<MouseWheel>,
        mut query: Query<(&Interaction, &Parent, &Children, &mut Style), With<Scroll>>,
        interactions: Query<&Interaction>,
    ) {
        events.iter().for_each(|MouseWheel { unit, y, .. }| {
            query
                .iter_mut()
                .filter(|(&interaction, parent, children, _)| {
                    let self_hover = interaction == Interaction::Hovered;
                    let child_hover = children.iter().any(|&child| {
                        if let Ok(&interaction) = interactions.get(child) {
                            interaction == Interaction::Hovered
                        } else {
                            false
                        }
                    });
                    let parent_hover = interactions
                        .get(parent.get())
                        .map_or(false, |&interaction| interaction == Interaction::Hovered);
                    self_hover || child_hover || parent_hover
                })
                .for_each(|(_, _, _, mut style)| {
                    let factor = 2.0;
                    let val = match unit {
                        MouseScrollUnit::Line => match style.top {
                            Val::Px(v) => v + (y * factor),
                            _ => (*y) * factor,
                        },
                        MouseScrollUnit::Pixel => match style.top {
                            Val::Px(v) => v + (y * factor),
                            _ => (*y) * factor,
                        },
                    };
                    style.top = Val::Px(val.min(0.0));
                });
        });
    }
}

use cursor::*;
mod cursor {
    use super::*;

    pub fn manage_cursor(
        events: Query<&Interaction, Changed<Interaction>>,
        mut window: Query<&mut Window, With<PrimaryWindow>>,
    ) {
        events.for_each(|interaction| {
            let mut win = window.single_mut();

            win.cursor.icon = match interaction {
                Interaction::None => CursorIcon::Default,
                Interaction::Hovered => CursorIcon::Hand,
                Interaction::Pressed => CursorIcon::Grabbing,
            }
        })
    }
}

pub use sort::*;
mod sort {
    use std::cmp::Ordering;

    use super::*;

    #[derive(Debug, Component)]
    pub struct Sorting(pub u8);

    pub fn manage_sort(
        mut events: Query<&mut Children, Changed<Children>>,
        sorting: Query<Option<&Sorting>>,
    ) {
        events.iter_mut().for_each(|mut children| {
            children.sort_by(|&a, &b| match (sorting.get(a), sorting.get(b)) {
                (Ok(Some(Sorting(ord_a))), Ok(Some(Sorting(ord_b)))) => {
                    if ord_a > ord_b {
                        Ordering::Greater
                    } else if ord_a < ord_b {
                        Ordering::Less
                    } else {
                        Ordering::Equal
                    }
                }
                (Ok(Some(_)), Err(_)) | (Ok(Some(_)), Ok(None)) => Ordering::Less,
                (Err(_), Ok(Some(_))) | (Ok(None), Ok(Some(_))) => Ordering::Greater,
                _ => Ordering::Equal,
            });
        })
    }
}