//! A command to rotate through scratch windows.

extern crate "rustc-serialize" as serialize;
extern crate i3;

use serialize::json::Json;

/// IPC includes.
use i3::ipc::{I3Proto, get_socket_path, open_socket};

/// Includes for operations on the layout tree.
use i3::tree::{iter_nodes, is_focused, is_scratch};

/// Finds a focused window inside a scratch container.
fn focused_scratch(node: &Json) -> Option<&Json> {
    iter_nodes(node)
        // Filter focused nodes. `d` is the depth in the tree
        // so `d > 0` excludes the root node.
        .filter(|&(n, d)| d > 0 && is_focused(n))
        // only return the node
        .map(|(n, _)| n)
        // return the first match
        .next()
}

/// Returns the focused scratch window. Or `None` if
/// a different window is focused.
fn get_focused_scratch(tree: &Json) -> Option<&Json> {
    // Iterate all the nodes in the tree.
    iter_nodes(tree)
        // Filter only scratch containers.
        .filter(|&(n, _)| is_scratch(n))
        // Find a focused window inside the scratch container.
        .filter_map(|(n, _)| focused_scratch(n))
        // return the first match
        .next()
}

fn main() {
    // Get the path to the i3 IPC socket and open it.
    let path = get_socket_path().unwrap();
    let mut sock = open_socket(&path).unwrap();

    let showit;

    // Get the tree as json objects.
    let tree = sock.request_tree().unwrap();
    // If a scratch window is focused, move id back to scratchpad.
    if get_focused_scratch(&tree).is_some() {
        sock.request_command("move scratchpad").unwrap();

        // Only show a window if there is not already another
        // scratch window below the moved one.
        let tree = sock.request_tree().unwrap();
        showit = !get_focused_scratch(&tree).is_some()
    } else {
        showit = true;
    }

    if showit {
        // Show the next scratchpad window.
        sock.request_command("scratchpad show").unwrap();
    }
}