//! Input stream wrappers for use in abortable_parser.
use std::convert::From;
use std::iter::Iterator;

use abortable_parser::iter::{SliceIter, StrIter};
use abortable_parser::{InputIter, Offsetable, Peekable, Positioned, Seekable, Span, SpanRange};

use crate::ast::{Position, Token};

#[derive(Debug)]
pub struct OffsetStrIter<'a> {
    contained: StrIter<'a>,
    line_offset: usize,
    col_offset: usize,
}

impl<'a> OffsetStrIter<'a> {
    pub fn new(input: &'a str) -> Self {
        Self::new_with_offsets(input, 0, 0)
    }

    pub fn new_with_offsets(input: &'a str, line_offset: usize, col_offset: usize) -> Self {
        OffsetStrIter {
            contained: StrIter::new(input),
            line_offset: line_offset,
            col_offset: col_offset,
        }
    }
}

impl<'a> Iterator for OffsetStrIter<'a> {
    type Item = &'a u8;

    fn next(&mut self) -> Option<Self::Item> {
        self.contained.next()
    }
}

impl<'a> Offsetable for OffsetStrIter<'a> {
    fn get_offset(&self) -> usize {
        self.contained.get_offset()
    }
}

impl<'a> Clone for OffsetStrIter<'a> {
    fn clone(&self) -> Self {
        OffsetStrIter {
            contained: self.contained.clone(),
            line_offset: self.line_offset,
            col_offset: self.col_offset,
        }
    }
}

impl<'a> From<&'a str> for OffsetStrIter<'a> {
    fn from(source: &'a str) -> Self {
        OffsetStrIter {
            contained: StrIter::new(source),
            line_offset: 0,
            col_offset: 0,
        }
    }
}

impl<'a> Seekable for OffsetStrIter<'a> {
    fn seek(&mut self, to: usize) -> usize {
        self.contained.seek(to)
    }
}

impl<'a> Span<&'a str> for OffsetStrIter<'a> {
    fn span(&self, idx: SpanRange) -> &'a str {
        self.contained.span(idx)
    }
}

impl<'a> Peekable<&'a u8> for OffsetStrIter<'a> {
    fn peek_next(&self) -> Option<&'a u8> {
        self.contained.peek_next()
    }
}

impl<'a> Positioned for OffsetStrIter<'a> {
    fn line(&self) -> usize {
        self.contained.line() + self.line_offset
    }

    fn column(&self) -> usize {
        self.contained.column() + self.col_offset
    }
}

impl<'a> InputIter for OffsetStrIter<'a> {}

impl<'a> From<&'a SliceIter<'a, Token>> for Position {
    fn from(source: &'a SliceIter<'a, Token>) -> Self {
        match source.peek_next() {
            Some(t) => t.pos.clone(),
            None => Position::new(0, 0, 0),
        }
    }
}

impl<'a> From<&'a OffsetStrIter<'a>> for Position {
    fn from(s: &'a OffsetStrIter<'a>) -> Position {
        Position::new(s.line(), s.column(), s.get_offset())
    }
}