use std::collections::HashMap;
use std::process::Command;
use std::thread;
use std::time::Duration;

use amane::{
    Animation, Blend, Center, Color, Full, Horizontal, InputArea, Layer, LayerWindow, Monitor, Padding, Parent, Pointer,
    Rectangle, Row, Service, Shadow, Stack, Start, Text, Vertical, Weight, Widget, Workspace, Workspaces, Zone,
};

use crate::edge::{self, Edge, HIDE_H, Part};
use crate::island::{CHIP_HOVER, CLEAR, COMPACT_H, HOVER_MS, SHADOW, TOP_GAP, backdrop, faded, mix};
use crate::{theme, tray};

// one round slot per workspace, inside the pill's inset; the pill sits LEFT px from the monitor's edge
const SLOT: f32 = 28.0;
const SLOT_GAP: f32 = 4.0;
const INSET: f32 = 5.0;
const LEFT: f32 = 12.0;

// between the workspaces' pill and the tray's
const TRAY_GAP: f32 = 8.0;

// each hovered workspace's highlight by workspace id, fading between 0 and 1
#[derive(Default)]
struct Hover(HashMap<i64, Animation>);

impl Service for Hover {
    fn new() -> Self {
        Self::default()
    }

    // changes only through input
    fn listen() {}
}

/*
 * a pill in the top left corner of every monitor with that monitor's hyprland workspaces,
 * in the wallpaper's colours like the island. the focused workspace takes the accent, the
 * one shown on another monitor a softer accent, empty ones dim; a click switches to it.
 * Workspaces follows hyprland's events, so nothing polls
 */
pub fn view(monitor: &Monitor) -> LayerWindow {
    theme::begin();

    let workspaces = Workspaces::read();
    let hover = Hover::read();

    // hidden on a fullscreen monitor until wanted, or for a moment on a workspace change (edge.rs)
    let (slide, switched, peeking) = {
        let edge = Edge::read();

        (edge::hidden_by(edge.part(Part::Workspaces, &monitor.name), 0.0, HIDE_H), edge.switched(&monitor.name), edge.shown(&monitor.name) == 0.0)
    };

    // special workspaces (scratchpads) aren't places to switch to
    let here: Vec<&Workspace> = workspaces
        .list()
        .iter()
        .filter(|workspace| workspace.output() == Some(monitor.name.as_str()))
        .filter(|workspace| !workspace.name().is_some_and(|name| name.starts_with("special")))
        .collect();

    let count = here.len() as f32;
    let width = 2.0 * INSET + count * SLOT + (count - 1.0).max(0.0) * SLOT_GAP;

    let window = |window_w: f32| {
        LayerWindow::new()
            .width(window_w)
            .height(TOP_GAP + COMPACT_H + SHADOW)
            .anchor_vertical(Vertical::Top)
            .anchor_horizontal(Horizontal::Left)
            // Overlay like the island: on a desktop of fullscreen windows, Top is hidden behind every one of them
            .layer(Layer::Overlay)
            .space(Zone::Ignore)
            .namespace("magic-workspaces")
    };

    // empty and click-through rather than hidden: see the island's view for why
    if here.is_empty() || slide <= -HIDE_H {
        return window(LEFT + width + SHADOW).click_through().child(Rectangle::new().width(0.0).height(0.0));
    }

    // the tray's pill right of this one (tray.rs), when an app has an icon there; a peek at a workspace change shows the workspaces alone
    let tray = if peeking { None } else { tray::pill(&monitor.name, LEFT + width + TRAY_GAP) };
    let tray_w = tray.as_ref().map_or(0.0, |(_, tray_w)| TRAY_GAP + tray_w);

    let window = window(LEFT + width + tray_w + SHADOW);

    let mut slots: Vec<Box<dyn Widget>> = Vec::new();

    /*
     * the focused workspace's accent is one disc under the row, so a change slides it from
     * the workspace before to this one (edge.rs times it); the slots themselves stay clear
     */
    let theme = theme::now();
    let slot_x = |index: usize| index as f32 * (SLOT + SLOT_GAP);

    let focused_at = here.iter().position(|workspace| workspace.focused());
    let came_from = switched.and_then(|(from, t)| here.iter().position(|workspace| workspace.id() == from).map(|at| (at, t)));

    let highlight_x = match (focused_at, came_from) {
        (Some(to), Some((from, t))) => {
            // ease in and out, with a slight stretch in the middle like a drop of ink
            let eased = t * t * (3.0 - 2.0 * t);

            Some(mix(slot_x(from), slot_x(to), eased))
        }
        (Some(to), None) => Some(slot_x(to)),
        _ => None,
    };

    let stretch = came_from.map_or(0.0, |(_, t)| (t * std::f32::consts::PI).sin() * 10.0);

    if switched.is_some() {
        amane::request_frame();
    }

    for workspace in &here {
        let id = workspace.id();
        let lit = hover.0.get(&id).map_or(0.0, Animation::value);

        // hyprland numbers its workspaces; a name-only one shows its first letter
        let label = match workspace.name() {
            Some(name) if workspace.index() == 0 => name.chars().next().map_or(String::new(), |letter| letter.to_uppercase().collect()),
            _ => workspace.index().to_string(),
        };

        let (fill, color, weight) = if workspace.focused() {
            // the label turns as the disc arrives
            let arrived = switched.map_or(1.0, |(_, t)| t);

            (CLEAR, Color::blend(theme.text, theme.on_accent, arrived), Weight::Bold)
        } else if workspace.active() {
            (faded(theme.accent, 70), theme.accent, Weight::Bold)
        } else {
            let resting = if workspace.windows() > 0 { theme.text } else { theme.dim };

            (Color::blend(CLEAR, CHIP_HOVER, lit), Color::blend(resting, theme.text, lit), Weight::Regular)
        };

        slots.push(Box::new(
            Rectangle::new()
                .width(SLOT)
                .height(SLOT)
                .radius(Full)
                .fill(fill)
                .align_child(Center, Center)
                .scale(1.0 + 0.08 * lit)
                .cursor(Pointer)
                .on_hover(move |inside| hovering(id, inside))
                .on_click(move |_| focus(id))
                .child(Text::new(label).size(12.0).weight(weight).color(color)),
        ));
    }

    let row_w = width - 2.0 * INSET;

    // the disc under the focused slot, a little wider while it's on its way
    let mut layers: Vec<Box<dyn Widget>> = Vec::new();

    if let Some(x) = highlight_x {
        layers.push(Box::new(Rectangle::new().width(SLOT + stretch).height(SLOT).radius(Full).fill(theme.accent).translate(x - stretch / 2.0, 0.0)));
    }

    layers.push(Box::new(Row::new(slots).gap(SLOT_GAP).align(Center)));

    let pill = Rectangle::new()
        .width(width)
        .height(COMPACT_H)
        .radius(Full)
        .fill(backdrop(&theme.surfaces(), 255))
        .border(1.0, theme.outline)
        .shadow(Shadow::drop(theme.accent).opacity(0.3).blur(22.0))
        .padding(INSET)
        .align_child(Start, Center)
        .on_hover(edge::over_bar)
        .child(Stack::new(layers).width(row_w).height(SLOT));

    // clicks next to the pills reach the windows underneath
    let mut regions = vec![InputArea { x: LEFT as i32, y: TOP_GAP as i32, width: width.ceil() as i32, height: COMPACT_H as i32 }];

    let mut pills: Vec<Box<dyn Widget>> = vec![Box::new(pill)];

    if let Some((tray, tray_pill_w)) = tray {
        regions.push(InputArea { x: (LEFT + width + TRAY_GAP) as i32, y: TOP_GAP as i32, width: tray_pill_w.ceil() as i32, height: COMPACT_H as i32 });
        pills.push(Box::new(tray));
    }

    window.input_region(regions).child(
        Rectangle::new()
            .width(Parent)
            .height(Parent)
            .padding(Padding { top: TOP_GAP, right: 0.0, bottom: 0.0, left: LEFT })
            .align_child(Start, Start)
            .translate(0.0, slide)
            .child(Row::new(pills).gap(TRAY_GAP).align(Start)),
    )
}

/*
 * switches to a workspace. amane's Workspaces::focus sends `dispatch workspace N`,
 * which hyprland 0.56 with a lua config turns into hl.dispatch(workspace N) and
 * rejects; this is the lua form the user's own keybinds use. on its own thread,
 * so hyprctl never holds up drawing. named workspaces (negative ids) aren't
 * switched: their lua form is unverified
 */
fn focus(id: i64) {
    if id < 0 {
        return;
    }

    thread::spawn(move || {
        let _ = Command::new("hyprctl").arg("dispatch").arg(format!("hl.dsp.focus({{ workspace = {id} }})")).output();
    });
}

/*
 * one workspace lit at a time: amane matches hover targets by their place in the frame,
 * so a workspace that closes under the pointer never hears it leave
 */
fn hovering(id: i64, inside: bool) {
    let mut hover = Hover::write();

    if inside {
        for (other, highlight) in &mut hover.0 {
            if *other != id {
                highlight.to(0.0);
            }
        }
    }

    hover
        .0
        .entry(id)
        .or_insert_with(|| Animation::new(0.0).duration(Duration::from_millis(HOVER_MS)))
        .to(if inside { 1.0 } else { 0.0 });
}