// Copyright 2018 Eduardo Sánchez Muñoz
//
// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
// http://opensource.org/licenses/MIT>, at your option. This file may not be
// copied, modified, or distributed except according to those terms.

/// Represents a position in a text file.
///
/// Lines and columns begin to count with zero.
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
pub struct Pos {
    pub line: u32,
    pub column: u32,
}

impl Pos {
    #[inline]
    pub fn new(line: u32, column: u32) -> Self {
        Self { line: line, column: column }
    }
}

/// Wrapper whose `Display` implementation prints
/// `self.0 + 1`, taking care of overflow.
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
pub struct ReprPosValue(pub u32);

impl std::fmt::Display for ReprPosValue {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        match self.0.checked_add(1) {
            Some(value) => std::fmt::Display::fmt(&value, f),
            None => f.write_str("4294967296"),
        }
    }
}

/// Maps nodes with their positions in the original text file.
#[derive(Clone, Debug, PartialEq, Eq, Hash)]
pub struct PosTree {
    pub pos: Pos,
    pub children: Vec<PosTree>,
}

impl PosTree {
    #[inline]
    pub fn new(pos: Pos) -> Self {
        Self {
            pos: pos,
            children: Vec::new(),
        }
    }

    /// Traverses a tree with indices from `path`. Similar to `Node::index_path`.
    pub fn index_path(&self, path: &[usize]) -> Option<&Self> {
        let mut current_node = self;
        for &index in path {
            if let Some(next_node) = self.children.get(index) {
                current_node = next_node;
            } else {
                return None;
            }
        }
        Some(current_node)
    }
}