use can_dbc::Dbc;
use eframe::egui;
use egui::ScrollArea;
use egui_ltreeview::{Action, TreeView};
use libsvld::DecodeResult;

pub struct SigNode {
    pub id: u64,
    pub name: String,
}

pub struct MsgNode {
    pub id: u64,
    pub label: String,
    pub signals: Vec<SigNode>,
}

const SIGNAL_FLAG: u64 = 1 << 63;

pub fn signal_node_id(msg_id: u32, sig_idx: usize) -> u64 {
    SIGNAL_FLAG | ((msg_id as u64) << 16) | (sig_idx as u64)
}

pub fn decode_signal_node_id(id: u64) -> Option<(u32, usize)> {
    if id & SIGNAL_FLAG == 0 {
        return None;
    }
    let msg_id = ((id >> 16) & 0xFFFF_FFFF) as u32;
    let sig_idx = (id & 0xFFFF) as usize;
    Some((msg_id, sig_idx))
}

pub fn build_tree(dbc: &Dbc, data: &DecodeResult) -> Vec<MsgNode> {
    let mut msgs: Vec<&libsvld::motec::MessageMetadata> = data.metadata.values().collect();
    msgs.sort_by_key(|m| m.id);
    msgs.into_iter()
        .map(|msg| {
            let name = dbc
                .messages
                .iter()
                .find(|x| x.id.raw() == msg.id)
                .map(|x| x.name.as_str())
                .unwrap_or("?");
            let label = format!("0x{:X}  {}", msg.id, name);
            let signals = msg
                .signals
                .iter()
                .enumerate()
                .map(|(sig_idx, signal)| SigNode {
                    id: signal_node_id(msg.id, sig_idx),
                    name: signal.name.clone(),
                })
                .collect();
            MsgNode {
                id: msg.id as u64,
                label,
                signals,
            }
        })
        .collect()
}

/// Render the side panel and return any signal IDs the user clicked to toggle.
pub fn show_side_panel(
    ui: &mut egui::Ui,
    filter: &mut String,
    tree: &[MsgNode],
) -> Vec<u64> {
    let mut toggles = Vec::new();
    egui::Panel::left(egui::Id::new("Signals"))
        .resizable(true)
        .show_inside(ui, |ui| {
            ui.add(
                egui::TextEdit::singleline(filter)
                    .hint_text("Filter messages/signals")
                    .desired_width(f32::INFINITY),
            );
            let needle = filter.trim().to_lowercase();
            ScrollArea::both()
                .scroll([true, true])
                .scroll_bar_visibility(
                    egui::scroll_area::ScrollBarVisibility::VisibleWhenNeeded,
                )
                .show(ui, |ui| {
                    let (_resp, actions) = TreeView::<u64>::new(
                        ui.make_persistent_id("SignalsTree"),
                    )
                    .show(ui, |builder| {
                        for msg in tree {
                            let msg_hit = needle.is_empty()
                                || msg.label.to_lowercase().contains(&needle);
                            let matching: Vec<&SigNode> = if msg_hit {
                                msg.signals.iter().collect()
                            } else {
                                msg.signals
                                    .iter()
                                    .filter(|s| s.name.to_lowercase().contains(&needle))
                                    .collect()
                            };
                            if !msg_hit && matching.is_empty() {
                                continue;
                            }
                            builder.dir(msg.id, msg.label.as_str());
                            for sig in matching {
                                builder.leaf(sig.id, sig.name.as_str());
                            }
                            builder.close_dir();
                        }
                    });
                    for action in actions {
                        if let Action::SetSelected(ids) = action {
                            for id in ids {
                                if id & SIGNAL_FLAG != 0 {
                                    toggles.push(id);
                                }
                            }
                        }
                    }
                });
        });
    toggles
}