use super::funejson::Value;
use super::todo_item::Todo;
use super::todo_item_validate_todo::{todos_from_value, todos_to_value};
use super::todo_list_update_todo::index_of_todo;

/// Move a todo to `to_index` in manual order (order ascending, ties by array
/// position, which need not already be sorted) and renumber every order 0 to
/// n-1. The result is in that manual order.
///
/// # Panics
/// On an unknown id or a `to_index` outside 0..n-1.
pub fn move_todo(todos: &[Todo], id: &str, to_index: i64) -> Vec<Todo> {
    let from = index_of_todo(todos, id);
    let last = todos.len() as i64 - 1;
    if to_index < 0 || to_index > last {
        panic!("toIndex must be between 0 and {}, received {}", last, to_index);
    }
    let mut positions: Vec<usize> = (0..todos.len()).collect();
    positions.sort_by_key(|&i| (todos[i].order, i));
    positions.retain(|&i| i != from);
    positions.insert(to_index as usize, from);
    positions
        .iter()
        .enumerate()
        .map(|(n, &i)| {
            let mut t = todos[i].clone();
            t.order = n as i64;
            t
        })
        .collect()
}

pub fn fune_vector(args: &[Value]) -> Value {
    let todos = todos_from_value(&args[0]);
    if let Value::Float(f) = &args[2] {
        panic!("toIndex must be between 0 and {}, received {}", todos.len() as i64 - 1, f);
    }
    todos_to_value(&move_todo(&todos, args[1].as_str(), args[2].as_i64()))
}