const Self = @This();

const std = @import("std");

const c = @import("c.zig");

const Box = @import("box.zig");
const Log = @import("log.zig").Log;
const Output = @import("output.zig");

output: *Output,
wlr_layer_surface: *c.wlr_layer_surface_v1,

/// True if the layer surface is currently mapped
mapped: bool,

box: Box,
layer: c.zwlr_layer_shell_v1_layer,

// Listeners active the entire lifetime of the layser surface
listen_destroy: c.wl_listener,
listen_map: c.wl_listener,
listen_unmap: c.wl_listener,

// Listeners only active while the layer surface is mapped
listen_commit: c.wl_listener,
listen_new_popup: c.wl_listener,

pub fn init(
    self: *Self,
    output: *Output,
    wlr_layer_surface: *c.wlr_layer_surface_v1,
    layer: c.zwlr_layer_shell_v1_layer,
) void {
    self.output = output;
    self.wlr_layer_surface = wlr_layer_surface;
    wlr_layer_surface.data = self;

    self.layer = layer;

    // Temporarily set mapped to true and apply the pending state to allow
    // for inital arrangement which sends the first configure.
    self.mapped = true;
    const stashed_state = wlr_layer_surface.current;
    wlr_layer_surface.current = wlr_layer_surface.client_pending;
    output.arrangeLayers();
    wlr_layer_surface.current = stashed_state;

    // Set up listeners that are active for the entire lifetime of the layer surface
    self.listen_destroy.notify = handleDestroy;
    c.wl_signal_add(&self.wlr_layer_surface.events.destroy, &self.listen_destroy);

    self.listen_map.notify = handleMap;
    c.wl_signal_add(&self.wlr_layer_surface.events.map, &self.listen_map);

    self.listen_unmap.notify = handleUnmap;
    c.wl_signal_add(&self.wlr_layer_surface.events.unmap, &self.listen_unmap);
}

fn handleDestroy(listener: ?*c.wl_listener, data: ?*c_void) callconv(.C) void {
    const self = @fieldParentPtr(Self, "listen_destroy", listener.?);
    const output = self.output;

    Log.Debug.log("Layer surface '{}' destroyed", .{self.wlr_layer_surface.namespace});

    // Remove listeners active the entire lifetime of the layer surface
    c.wl_list_remove(&self.listen_destroy.link);
    c.wl_list_remove(&self.listen_map.link);
    c.wl_list_remove(&self.listen_unmap.link);

    const node = @fieldParentPtr(std.TailQueue(Self).Node, "data", self);
    output.layers[@intCast(usize, @enumToInt(self.layer))].remove(node);
    output.root.server.allocator.destroy(node);

    self.output.arrangeLayers();
}

fn handleMap(listener: ?*c.wl_listener, data: ?*c_void) callconv(.C) void {
    const self = @fieldParentPtr(Self, "listen_map", listener.?);
    const wlr_layer_surface = self.wlr_layer_surface;

    Log.Debug.log("Layer surface '{}' mapped.", .{wlr_layer_surface.namespace});

    self.mapped = true;

    // Add listeners that are only active while mapped
    self.listen_commit.notify = handleCommit;
    c.wl_signal_add(&wlr_layer_surface.surface.*.events.commit, &self.listen_commit);

    self.listen_new_popup.notify = handleNewPopup;
    c.wl_signal_add(&wlr_layer_surface.events.new_popup, &self.listen_new_popup);

    c.wlr_surface_send_enter(
        wlr_layer_surface.surface,
        wlr_layer_surface.output,
    );
}

fn handleUnmap(listener: ?*c.wl_listener, data: ?*c_void) callconv(.C) void {
    const self = @fieldParentPtr(Self, "listen_unmap", listener.?);

    Log.Debug.log("Layer surface '{}' unmapped.", .{self.wlr_layer_surface.namespace});

    // This is a bit ugly: we need to use the wlr bool here since surfaces
    // may be closed during the inital configure since we set our mapped
    // bool to true so that we can avoid making the arrange function even
    // more complex.
    //
    // TODO(wlroots): Remove this check on updating
    // https://github.com/swaywm/wlroots/commit/11e94c406bb75c9a8990ce99489798411deb110c
    if (self.wlr_layer_surface.mapped) {
        // remove listeners only active while the layer surface is mapped
        c.wl_list_remove(&self.listen_commit.link);
        c.wl_list_remove(&self.listen_new_popup.link);
    }

    self.mapped = false;

    // If the unmapped surface is focused, clear focus
    var it = self.output.root.server.input_manager.seats.first;
    while (it) |node| : (it = node.next) {
        const seat = &node.data;
        if (seat.focused_layer) |current_focus| {
            if (current_focus == self) {
                seat.setFocusRaw(.{ .none = {} });
            }
        }
    }

    // This gives exclusive focus to a keyboard interactive top or overlay layer
    // surface if there is one.
    self.output.arrangeLayers();

    // Ensure that focus is given to the appropriate view if there is no
    // other top/overlay layer surface to grab focus.
    it = self.output.root.server.input_manager.seats.first;
    while (it) |node| : (it = node.next) {
        const seat = &node.data;
        seat.focus(null);
    }
}

fn handleCommit(listener: ?*c.wl_listener, data: ?*c_void) callconv(.C) void {
    const self = @fieldParentPtr(Self, "listen_commit", listener.?);
    const wlr_layer_surface = self.wlr_layer_surface;

    if (self.wlr_layer_surface.output == null) {
        Log.Error.log("Layer surface committed with null output", .{});
        return;
    }

    // If the layer changed, move the LayerSurface to the proper list
    if (self.layer != self.wlr_layer_surface.current.layer) {
        const node = @fieldParentPtr(std.TailQueue(Self).Node, "data", self);

        const old_layer_idx = @intCast(usize, @enumToInt(self.layer));
        self.output.layers[old_layer_idx].remove(node);

        self.layer = self.wlr_layer_surface.current.layer;

        const new_layer_idx = @intCast(usize, @enumToInt(self.layer));
        self.output.layers[new_layer_idx].append(node);
    }

    // TODO: only reconfigure if things haven't changed
    // https://github.com/swaywm/wlroots/issues/1079
    self.output.arrangeLayers();
}

fn handleNewPopup(listener: ?*c.wl_listener, data: ?*c_void) callconv(.C) void {
    const self = @fieldParentPtr(Self, "listen_new_popup", listener.?);
    Log.Debug.log("new layer surface popup.", .{});
    // TODO: handle popups
    unreachable;
}