use super::*;

use std::cmp::Ordering;

#[derive(PartialEq, Eq)]
pub struct DirectoryChild {
    pub byte_path: Vec<u8>,
    pub entry_type: EntryType,
}

impl PartialOrd for DirectoryChild {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

impl Ord for DirectoryChild {
    fn cmp(&self, other: &Self) -> Ordering {
        match self.entry_type.cmp(&other.entry_type) {
            Ordering::Equal =>
                compare_ascii_arrays(&self.byte_path,&other.byte_path),
            other => other,
        }
    }
}

// Compare two ASCII arrays in case-agnostic alphabetic order.
fn compare_ascii_arrays(left: &[u8], right: &[u8]) -> Ordering {
    let l = std::cmp::min(left.len(), right.len());
    let lhs = &left[..l];
    let rhs = &right[..l];

    for i in 0..l {
        let a = remap_ascii(lhs[i]);
        let b = remap_ascii(rhs[i]);
        match a.cmp(&b) {
            Ordering::Equal => (),
            non_eq => return non_eq,
        }
    }

    left.len().cmp(&right.len())
}

// Remap ASCII values so that they sort in case-agnostic alphabetic order:
//    !"#$%&'()*+,-./0123456789:;<=>?
//   @`AaBbCcDdEeFfGgHhIiJjKkLlMmNnOo
//   PpQqRrSsTtUuVvWwXxYyZz[{\|]}^~_
fn remap_ascii(c: u8) -> u8 {
    if 0x40 <= c && c <= 0x5F {
        (c - 0x40) * 2 + 0x40
    } else if 0x60 <= c && c <= 0x7F {
        (c - 0x60) * 2 + 0x41
    } else {
        c
    }
}