use std::collections::HashMap;
use std::env;
use std::time::Instant;

use asd::gfa::{Entry, Orientation};
use asd::parser;
use crossbeam::channel::{unbounded, Receiver, Sender};
use eframe::{run_native, App, CreationContext};
use egui::{CollapsingHeader, Context, Pos2, ScrollArea, Slider, Ui};
use egui_graphs::events::Event;
use egui_graphs::{to_graph, DefaultEdgeShape, DefaultNodeShape, Graph, GraphView};
use fdg_sim::glam::Vec3;
use fdg_sim::{ForceGraph, ForceGraphHelper, Simulation, SimulationParameters};
use petgraph::stable_graph::{DefaultIx, EdgeIndex, NodeIndex, StableGraph};
use petgraph::Directed;
use rand::Rng;
use settings::{SettingsInteraction, SettingsNavigation, SettingsStyle};

mod settings;

const SIMULATION_DT: f32 = 0.035;
const EVENTS_LIMIT: usize = 100;

pub struct ConfigurableApp {
    g: Graph<(String, Orientation), (), Directed, DefaultIx>,
    sim: Simulation<(), f32>,

    // settings_graph: SettingsGraph,
    settings_interaction: SettingsInteraction,
    settings_navigation: SettingsNavigation,
    settings_style: SettingsStyle,

    last_events: Vec<String>,

    simulation_stopped: bool,

    fps: f64,
    last_update_time: Instant,
    frames_last_time_span: usize,

    event_publisher: Sender<Event>,
    event_consumer: Receiver<Event>,

    pan: Option<[f32; 2]>,
    zoom: Option<f32>,
}

impl ConfigurableApp {
    fn new(_: &CreationContext<'_>) -> Self {
        // let settings_graph = SettingsGraph::default();
        let (g, sim) = generate();
        let (event_publisher, event_consumer) = unbounded();
        Self {
            g,
            sim,

            event_consumer,
            event_publisher,

            // settings_graph,
            settings_interaction: SettingsInteraction::default(),
            settings_navigation: SettingsNavigation::default(),
            settings_style: SettingsStyle::default(),

            last_events: Vec::default(),

            simulation_stopped: false,

            fps: 0.,
            last_update_time: Instant::now(),
            frames_last_time_span: 0,

            pan: Option::default(),
            zoom: Option::default(),
        }
    }

    fn update_simulation(&mut self) {
        if self.simulation_stopped {
            return;
        }

        // the following manipulations is a hack to avoid having looped edges in the simulation
        // because they cause the simulation to blow up;
        // this is the issue of the fdg_sim engine we use for the simulation
        // https://github.com/grantshandy/fdg/issues/10
        // * remove loop edges
        // * update simulation
        // * restore loop edges

        // remove looped edges
        let looped_nodes = {
            let graph = self.sim.get_graph_mut();
            let mut looped_nodes = vec![];
            let mut looped_edges = vec![];
            graph.edge_indices().for_each(|idx| {
                let edge = graph.edge_endpoints(idx).unwrap();
                let looped = edge.0 == edge.1;
                if looped {
                    looped_nodes.push((edge.0, ()));
                    looped_edges.push(idx);
                }
            });

            for idx in looped_edges {
                graph.remove_edge(idx);
            }

            self.sim.update(SIMULATION_DT);

            looped_nodes
        };

        // restore looped edges
        let graph = self.sim.get_graph_mut();
        for (idx, _) in looped_nodes.iter() {
            graph.add_edge(*idx, *idx, 1.);
        }
    }

    /// Syncs the graph with the simulation.
    ///
    /// Changes location of nodes in `g` according to the locations in `sim`. If node from `g` is dragged its location is prioritized
    /// over the location of the corresponding node from `sim` and this location is set to the node from the `sim`.
    ///
    /// If node or edge is selected it is added to the corresponding selected field in `self`.
    fn sync_graph_with_simulation(&mut self) {
        let g_indices = self.g.g.node_indices().collect::<Vec<_>>();
        for g_n_idx in &g_indices {
            let g_n = self.g.g.node_weight_mut(*g_n_idx).unwrap();
            let sim_n = self.sim.get_graph_mut().node_weight_mut(*g_n_idx).unwrap();

            let loc = sim_n.location;
            g_n.set_location(Pos2::new(loc.x, loc.y));
        }

        // reset the weights of the edges
        self.sim.get_graph_mut().edge_weights_mut().for_each(|w| {
            *w = 1.;
        });
    }

    fn update_fps(&mut self) {
        self.frames_last_time_span += 1;
        let now = Instant::now();
        let elapsed = now.duration_since(self.last_update_time);
        if elapsed.as_secs() >= 1 {
            self.last_update_time = now;
            self.fps = self.frames_last_time_span as f64 / elapsed.as_secs_f64();
            self.frames_last_time_span = 0;
        }
    }

    fn reset_graph(&mut self, ui: &mut Ui) {
        // let settings_graph = SettingsGraph::default();
        let (g, sim) = generate();

        self.g = g;
        self.sim = sim;
        // self.settings_graph = settings_graph;
        self.last_events = Vec::default();

        GraphView::<(), (), Directed, DefaultIx>::reset_metadata(ui);
    }

    fn handle_events(&mut self) {
        self.event_consumer.try_iter().for_each(|e| {
            if self.last_events.len() > EVENTS_LIMIT {
                self.last_events.remove(0);
            }
            self.last_events.push(serde_json::to_string(&e).unwrap());

            match e {
                Event::Pan(payload) => match self.pan {
                    Some(pan) => {
                        self.pan = Some([pan[0] + payload.diff[0], pan[1] + payload.diff[1]]);
                    }
                    None => {
                        self.pan = Some(payload.diff);
                    }
                },
                Event::Zoom(z) => {
                    match self.zoom {
                        Some(zoom) => {
                            self.zoom = Some(zoom + z.diff);
                        }
                        None => {
                            self.zoom = Some(z.diff);
                        }
                    };
                }
                Event::NodeMove(payload) => {
                    let node_id = NodeIndex::new(payload.id);
                    let diff = Vec3::new(payload.diff[0], payload.diff[1], 0.);

                    let node = self.sim.get_graph_mut().node_weight_mut(node_id).unwrap();
                    node.location += diff;
                }
                _ => {}
            }
        });
    }

    // fn random_node_idx(&self) -> Option<NodeIndex> {
    //     let nodes_cnt = self.g.node_count();
    //     if nodes_cnt == 0 {
    //         return None;
    //     }

    //     let random_n_idx = rand::thread_rng().gen_range(0..nodes_cnt);
    //     self.g.g.node_indices().nth(random_n_idx)
    // }

    // fn random_edge_idx(&self) -> Option<EdgeIndex> {
    //     let edges_cnt = self.g.edge_count();
    //     if edges_cnt == 0 {
    //         return None;
    //     }

    //     let random_e_idx = rand::thread_rng().gen_range(0..edges_cnt);
    //     self.g.g.edge_indices().nth(random_e_idx)
    // }

    // fn remove_random_node(&mut self) {
    //     let idx = self.random_node_idx().unwrap();
    //     self.remove_node(idx);
    // }

    // fn add_random_node(&mut self) {
    //     let random_n_idx = self.random_node_idx();
    //     if random_n_idx.is_none() {
    //         return;
    //     }

    //     let random_n = self.g.node(random_n_idx.unwrap()).unwrap();

    //     // location of new node is in surrounging of random existing node
    //     let mut rng = rand::thread_rng();
    //     let location = Pos2::new(
    //         random_n.location().x + 10. + rng.gen_range(0. ..50.),
    //         random_n.location().y + 10. + rng.gen_range(0. ..50.),
    //     );

    //     let idx = self.g.add_node_with_location((), location);

    //     let mut sim_node = fdg_sim::Node::new(idx.index().to_string().as_str(), ());
    //     sim_node.location = Vec3::new(location.x, location.y, 0.);
    //     self.sim.get_graph_mut().add_node(sim_node);
    // }

    // fn remove_node(&mut self, idx: NodeIndex) {
    //     self.g.remove_node(idx);

    //     self.sim.get_graph_mut().remove_node(idx).unwrap();

    //     // update edges count
    //     self.settings_graph.count_edge = self.g.edge_count();
    // }

    // fn add_random_edge(&mut self) {
    //     let random_start = self.random_node_idx().unwrap();
    //     let random_end = self.random_node_idx().unwrap();

    //     self.add_edge(random_start, random_end);
    // }

    // fn add_edge(&mut self, start: NodeIndex, end: NodeIndex) {
    //     self.g.add_edge(start, end, ());

    //     self.sim.get_graph_mut().add_edge(start, end, 1.);
    // }

    // fn remove_random_edge(&mut self) {
    //     let random_e_idx = self.random_edge_idx();
    //     if random_e_idx.is_none() {
    //         return;
    //     }
    //     let endpoints = self.g.edge_endpoints(random_e_idx.unwrap()).unwrap();

    //     self.remove_edge(endpoints.0, endpoints.1);
    // }

    // fn remove_edge(&mut self, start: NodeIndex, end: NodeIndex) {
    //     let (g_idx, _) = self.g.edges_connecting(start, end).next().unwrap();
    //     self.g.remove_edge(g_idx);

    //     let sim_idx = self.sim.get_graph_mut().find_edge(start, end).unwrap();
    //     self.sim.get_graph_mut().remove_edge(sim_idx).unwrap();
    // }

    fn draw_section_app(&mut self, ui: &mut Ui) {
        CollapsingHeader::new("App Config")
            .default_open(true)
            .show(ui, |ui| {
                ui.add_space(10.);

                ui.label("Simulation");
                ui.separator();

                ui.horizontal(|ui| {
                    if ui
                        .button(match self.simulation_stopped {
                            true => "start",
                            false => "stop",
                        })
                        .clicked()
                    {
                        self.simulation_stopped = !self.simulation_stopped;
                    };
                    if ui.button("reset").clicked() {
                        self.reset_graph(ui);
                    }
                });

                ui.add_space(10.);

                self.draw_counts_sliders(ui);

                ui.add_space(10.);

                ui.separator();
            });
    }

    fn draw_section_widget(&mut self, ui: &mut Ui) {
        CollapsingHeader::new("Widget")
        .default_open(true)
        .show(ui, |ui| {
            CollapsingHeader::new("Navigation").default_open(true).show(ui, |ui|{
                if ui
                    .checkbox(&mut self.settings_navigation.fit_to_screen_enabled, "fit_to_screen")
                    .changed()
                    && self.settings_navigation.fit_to_screen_enabled
                {
                    self.settings_navigation.zoom_and_pan_enabled = false
                };
                ui.label("Enable fit to screen to fit the graph to the screen on every frame.");

                ui.add_space(5.);

                ui.add_enabled_ui(!self.settings_navigation.fit_to_screen_enabled, |ui| {
                    ui.vertical(|ui| {
                        ui.checkbox(&mut self.settings_navigation.zoom_and_pan_enabled, "zoom_and_pan");
                        ui.label("Zoom with ctrl + mouse wheel, pan with middle mouse drag.");
                    }).response.on_disabled_hover_text("disable fit_to_screen to enable zoom_and_pan");
                });
            });

            CollapsingHeader::new("Style").show(ui, |ui| {
                ui.checkbox(&mut self.settings_style.labels_always, "labels_always");
                ui.label("Wheter to show labels always or when interacted only.");
            });

            CollapsingHeader::new("Interaction").show(ui, |ui| {
                if ui.checkbox(&mut self.settings_interaction.dragging_enabled, "dragging_enabled").clicked() && self.settings_interaction.dragging_enabled {
                    self.settings_interaction.node_clicking_enabled = true;
                };
                ui.label("To drag use LMB click + drag on a node.");

                ui.add_space(5.);

                ui.add_enabled_ui(!(self.settings_interaction.dragging_enabled || self.settings_interaction.node_selection_enabled || self.settings_interaction.node_selection_multi_enabled), |ui| {
                    ui.vertical(|ui| {
                        ui.checkbox(&mut self.settings_interaction.node_clicking_enabled, "node_clicking_enabled");
                        ui.label("Check click events in last events");
                    }).response.on_disabled_hover_text("node click is enabled when any of the interaction is also enabled");
                });

                ui.add_space(5.);

                ui.add_enabled_ui(!self.settings_interaction.node_selection_multi_enabled, |ui| {
                    ui.vertical(|ui| {
                        if ui.checkbox(&mut self.settings_interaction.node_selection_enabled, "node_selection_enabled").clicked() && self.settings_interaction.node_selection_enabled {
                            self.settings_interaction.node_clicking_enabled = true;
                        };
                        ui.label("Enable select to select nodes with LMB click. If node is selected clicking on it again will deselect it.");
                    }).response.on_disabled_hover_text("node_selection_multi_enabled enables select");
                });

                if ui.checkbox(&mut self.settings_interaction.node_selection_multi_enabled, "node_selection_multi_enabled").changed() && self.settings_interaction.node_selection_multi_enabled {
                    self.settings_interaction.node_clicking_enabled = true;
                    self.settings_interaction.node_selection_enabled = true;
                }
                ui.label("Enable multiselect to select multiple nodes.");

                ui.add_space(5.);

                ui.add_enabled_ui(!(self.settings_interaction.edge_selection_enabled || self.settings_interaction.edge_selection_multi_enabled), |ui| {
                    ui.vertical(|ui| {
                        ui.checkbox(&mut self.settings_interaction.edge_clicking_enabled, "edge_clicking_enabled");
                        ui.label("Check click events in last events");
                    }).response.on_disabled_hover_text("edge click is enabled when any of the interaction is also enabled");
                });

                ui.add_space(5.);

                ui.add_enabled_ui(!self.settings_interaction.edge_selection_multi_enabled, |ui| {
                    ui.vertical(|ui| {
                        if ui.checkbox(&mut self.settings_interaction.edge_selection_enabled, "edge_selection_enabled").clicked() && self.settings_interaction.edge_selection_enabled {
                            self.settings_interaction.edge_clicking_enabled = true;
                        };
                        ui.label("Enable select to select edges with LMB click. If edge is selected clicking on it again will deselect it.");
                    }).response.on_disabled_hover_text("edge_selection_multi_enabled enables select");
                });

                if ui.checkbox(&mut self.settings_interaction.edge_selection_multi_enabled, "edge_selection_multi_enabled").changed() && self.settings_interaction.edge_selection_multi_enabled {
                    self.settings_interaction.edge_clicking_enabled = true;
                    self.settings_interaction.edge_selection_enabled = true;
                }
                ui.label("Enable multiselect to select multiple edges.");
            });

            CollapsingHeader::new("Selected").default_open(true).show(ui, |ui| {
                ScrollArea::vertical().auto_shrink([false, true]).max_height(200.).show(ui, |ui| {
                    self.g.selected_nodes().iter().for_each(|node| {
                        ui.label(format!("{node:?}"));
                    });
                    self.g.selected_edges().iter().for_each(|edge| {
                        ui.label(format!("{edge:?}"));
                    });
                });
            });

            CollapsingHeader::new("Last Events").default_open(true).show(ui, |ui| {
                ScrollArea::vertical().auto_shrink([false, true]).max_height(200.).show(ui, |ui| {
                    self.last_events.iter().rev().for_each(|event| {
                        ui.label(event);
                    });
                });
            });
        });
    }

    fn draw_section_debug(&mut self, ui: &mut Ui) {
        CollapsingHeader::new("Debug")
            .default_open(true)
            .show(ui, |ui| {
                if let Some(zoom) = self.zoom {
                    ui.label(format!("zoom: {:.5}", zoom));
                };
                if let Some(pan) = self.pan {
                    ui.label(format!("pan: [{:.5}, {:.5}]", pan[0], pan[1]));
                };

                ui.label(format!("FPS: {:.1}", self.fps));
            });
    }

    fn draw_counts_sliders(&mut self, ui: &mut Ui) {
        // ui.horizontal(|ui| {
        //     let before = self.settings_graph.count_node as i32;

        //     ui.add(Slider::new(&mut self.settings_graph.count_node, 1..=2500).text("nodes"));

        //     let delta = self.settings_graph.count_node as i32 - before;
        //     (0..delta.abs()).for_each(|_| {
        //         if delta > 0 {
        //             self.add_random_node();
        //             return;
        //         };
        //         self.remove_random_node();
        //     });
        // });

        // ui.horizontal(|ui| {
        //     let before = self.settings_graph.count_edge as i32;

        //     ui.add(Slider::new(&mut self.settings_graph.count_edge, 0..=5000).text("edges"));

        //     let delta = self.settings_graph.count_edge as i32 - before;
        //     (0..delta.abs()).for_each(|_| {
        //         if delta > 0 {
        //             self.add_random_edge();
        //             return;
        //         };
        //         self.remove_random_edge();
        //     });
        // });
    }
}

impl App for ConfigurableApp {
    fn update(&mut self, ctx: &Context, _: &mut eframe::Frame) {
        egui::SidePanel::right("right_panel")
            .min_width(250.)
            .show(ctx, |ui| {
                ScrollArea::vertical().show(ui, |ui| {
                    self.draw_section_app(ui);
                    ui.add_space(10.);
                    self.draw_section_debug(ui);
                    ui.add_space(10.);
                    self.draw_section_widget(ui);
                });
            });

        egui::CentralPanel::default().show(ctx, |ui| {
            let settings_interaction = &egui_graphs::SettingsInteraction::new()
                .with_node_selection_enabled(self.settings_interaction.node_selection_enabled)
                .with_node_selection_multi_enabled(
                    self.settings_interaction.node_selection_multi_enabled,
                )
                .with_dragging_enabled(self.settings_interaction.dragging_enabled)
                .with_node_clicking_enabled(self.settings_interaction.node_clicking_enabled)
                .with_edge_clicking_enabled(self.settings_interaction.edge_clicking_enabled)
                .with_edge_selection_enabled(self.settings_interaction.edge_selection_enabled)
                .with_edge_selection_multi_enabled(
                    self.settings_interaction.edge_selection_multi_enabled,
                );
            let settings_navigation = &egui_graphs::SettingsNavigation::new()
                .with_zoom_and_pan_enabled(self.settings_navigation.zoom_and_pan_enabled)
                .with_fit_to_screen_enabled(self.settings_navigation.fit_to_screen_enabled)
                .with_zoom_speed(self.settings_navigation.zoom_speed);
            let settings_style = &egui_graphs::SettingsStyle::new()
                .with_labels_always(self.settings_style.labels_always);
            ui.add(
                &mut GraphView::<_, _, _, _, DefaultNodeShape, DefaultEdgeShape>::new(&mut self.g)
                    .with_interactions(settings_interaction)
                    .with_navigations(settings_navigation)
                    .with_styles(settings_style)
                    .with_events(&self.event_publisher),
            );
        });

        self.handle_events();
        self.sync_graph_with_simulation();

        self.update_simulation();
        self.update_fps();
    }
}

fn generate() -> (
    Graph<(String, Orientation), (), Directed, DefaultIx>,
    Simulation<(), f32>,
) {
    let mut g: StableGraph<(String, Orientation), ()> = StableGraph::new();

    let file = std::fs::File::open(env::args().nth(1).expect("missing gfa file argument")).unwrap();
    let entries = parser::parse_source(file).unwrap();

    let mut index_map = HashMap::new();

    for entry in entries {
        // println!("{:?}", entry);

        if let Entry::Link {
            from,
            from_orient,
            to,
            to_orient,
        } = entry
        {
            // add first node if not present
            let a = index_map
                .entry(from.clone())
                .or_insert_with(|| g.add_node((from.clone(), from_orient)))
                .to_owned();

            // add second node if not present
            let b = index_map
                .entry(to.clone())
                .or_insert_with(|| g.add_node((to.clone(), to_orient)))
                .to_owned();

            g.add_edge(a, b, ());
        }
    }

    let g = Graph::from(&g);

    let sim = construct_simulation(&g);

    (g, sim)
}

fn construct_simulation(
    g: &Graph<(String, Orientation), (), Directed, DefaultIx>,
) -> Simulation<(), f32> {
    // create force graph
    let mut force_graph = ForceGraph::with_capacity(g.g.node_count(), g.g.edge_count());
    g.g.node_indices().for_each(|idx| {
        let idx = idx.index();
        force_graph.add_force_node(format!("{idx}").as_str(), ());
    });
    g.g.edge_indices().for_each(|idx| {
        let (source, target) = g.g.edge_endpoints(idx).unwrap();
        force_graph.add_edge(source, target, 1.);
    });

    // initialize simulation
    let mut params = SimulationParameters::default();
    let force = fdg_sim::force::fruchterman_reingold_weighted(100., 0.75);
    params.set_force(force);

    Simulation::from_graph(force_graph, params)
}

// fn generate_random_graph(node_count: usize, edge_count: usize) -> Graph<(), ()> {
//     let mut rng = rand::thread_rng();
//     let mut graph = StableGraph::new();

//     // add nodes
//     for _ in 0..node_count {
//         graph.add_node(());
//     }

//     // add random edges
//     for _ in 0..edge_count {
//         let source = rng.gen_range(0..node_count);
//         let target = rng.gen_range(0..node_count);

//         graph.add_edge(NodeIndex::new(source), NodeIndex::new(target), ());
//     }

//     to_graph(&graph)
// }

fn main() {
    let native_options = eframe::NativeOptions::default();
    run_native(
        "egui_graphs_configurable_demo",
        native_options,
        Box::new(|cc| Box::new(ConfigurableApp::new(cc))),
    )
    .unwrap();
}