#[cfg(feature = "std")]
use proptest::prelude::*;

use crate::error::ErrMode::Backtrack;
use crate::error::{ErrorKind, InputError};
use crate::token::tag;
use crate::{
    combinator::{separated, separated_pair},
    PResult, Parser,
};

use super::*;

#[cfg(feature = "std")]
#[test]
fn test_fxhashmap_compiles() {
    let input = "a=b";
    fn pair(i: &mut &str) -> PResult<(char, char)> {
        let out = separated_pair('a', '=', 'b').parse_next(i)?;
        Ok(out)
    }

    let _: rustc_hash::FxHashMap<char, char> = separated(0.., pair, ',').parse(input).unwrap();
}

#[test]
fn test_offset_u8() {
    let s = b"abcd123";
    let a = &s[..];
    let b = &a[2..];
    let c = &a[..4];
    let d = &a[3..5];
    assert_eq!(b.offset_from(&a), 2);
    assert_eq!(c.offset_from(&a), 0);
    assert_eq!(d.offset_from(&a), 3);
}

#[test]
fn test_offset_str() {
    let a = "abcřèÂßÇd123";
    let b = &a[7..];
    let c = &a[..5];
    let d = &a[5..9];
    assert_eq!(b.offset_from(&a), 7);
    assert_eq!(c.offset_from(&a), 0);
    assert_eq!(d.offset_from(&a), 5);
}

#[test]
#[cfg(feature = "alloc")]
fn test_bit_stream_empty() {
    let i = (&b""[..], 0);

    let actual = i.iter_offsets().collect::<crate::lib::std::vec::Vec<_>>();
    assert_eq!(actual, vec![]);

    let actual = i.eof_offset();
    assert_eq!(actual, 0);

    let actual = i.peek_token();
    assert_eq!(actual, None);

    let actual = i.offset_for(|b| b);
    assert_eq!(actual, None);

    let actual = i.offset_at(1);
    assert_eq!(actual, Err(Needed::new(1)));

    let (actual_input, actual_slice) = i.peek_slice(0);
    assert_eq!(actual_input, (&b""[..], 0));
    assert_eq!(actual_slice, (&b""[..], 0, 0));
}

#[test]
#[cfg(feature = "alloc")]
fn test_bit_offset_empty() {
    let i = (&b""[..], 0);

    let actual = i.offset_from(&i);
    assert_eq!(actual, 0);
}

#[cfg(feature = "std")]
proptest! {
  #[test]
  #[cfg_attr(miri, ignore)]  // See https://github.com/AltSysrq/proptest/issues/253
  fn bit_stream(byte_len in 0..20usize, start in 0..160usize) {
        bit_stream_inner(byte_len, start);
  }
}

#[cfg(feature = "std")]
fn bit_stream_inner(byte_len: usize, start: usize) {
    let start = start.min(byte_len * 8);
    let start_byte = start / 8;
    let start_bit = start % 8;

    let bytes = vec![0b1010_1010; byte_len];
    let i = (&bytes[start_byte..], start_bit);

    let mut curr_i = i;
    let mut curr_offset = 0;
    while let Some((next_i, _token)) = curr_i.peek_token() {
        let to_offset = curr_i.offset_from(&i);
        assert_eq!(curr_offset, to_offset);

        let (slice_i, _) = i.peek_slice(curr_offset);
        assert_eq!(curr_i, slice_i);

        let at_offset = i.offset_at(curr_offset).unwrap();
        assert_eq!(curr_offset, at_offset);

        let eof_offset = curr_i.eof_offset();
        let (next_eof_i, eof_slice) = curr_i.peek_slice(eof_offset);
        assert_eq!(next_eof_i, (&b""[..], 0));
        let eof_slice_i = (eof_slice.0, eof_slice.1);
        assert_eq!(eof_slice_i, curr_i);

        curr_offset += 1;
        curr_i = next_i;
    }
    assert_eq!(i.eof_offset(), curr_offset);
}

#[test]
fn test_partial_complete() {
    let mut i = Partial::new(&b""[..]);
    assert!(Partial::<&[u8]>::is_partial_supported());

    assert!(i.is_partial(), "incomplete by default");
    let incomplete_state = i.complete();
    assert!(!i.is_partial(), "the stream should be marked as complete");

    i.restore_partial(incomplete_state);
    assert!(i.is_partial(), "incomplete stream state should be restored");
}

#[test]
fn test_custom_slice() {
    type Token = usize;
    type TokenSlice<'i> = &'i [Token];

    let mut tokens: TokenSlice<'_> = &[1, 2, 3, 4];

    let input = &mut tokens;
    let start = input.checkpoint();
    let _ = input.next_token();
    let _ = input.next_token();
    let offset = input.offset_from(&start);
    assert_eq!(offset, 2);
}

#[test]
fn test_tag_support_char() {
    assert_eq!(
        tag::<_, _, InputError<_>>('π').parse_peek("π"),
        Ok(("", "π"))
    );
    assert_eq!(
        tag::<_, _, InputError<_>>('π').parse_peek("π3.14"),
        Ok(("3.14", "π"))
    );

    assert_eq!(
        tag::<_, _, InputError<_>>("π").parse_peek("π3.14"),
        Ok(("3.14", "π"))
    );

    assert_eq!(
        tag::<_, _, InputError<_>>('-').parse_peek("π"),
        Err(Backtrack(InputError::new("π", ErrorKind::Tag)))
    );

    assert_eq!(
        tag::<_, Partial<&[u8]>, InputError<_>>('π').parse_peek(Partial::new(b"\xCF\x80")),
        Ok((Partial::new(Default::default()), "π".as_bytes()))
    );
    assert_eq!(
        tag::<_, &[u8], InputError<_>>('π').parse_peek(b"\xCF\x80"),
        Ok((Default::default(), "π".as_bytes()))
    );

    assert_eq!(
        tag::<_, Partial<&[u8]>, InputError<_>>('π').parse_peek(Partial::new(b"\xCF\x803.14")),
        Ok((Partial::new(&b"3.14"[..]), "π".as_bytes()))
    );
    assert_eq!(
        tag::<_, &[u8], InputError<_>>('π').parse_peek(b"\xCF\x80"),
        Ok((Default::default(), "π".as_bytes()))
    );

    assert_eq!(
        tag::<_, &[u8], InputError<_>>('π').parse_peek(b"\xCF\x803.14"),
        Ok((&b"3.14"[..], "π".as_bytes()))
    );

    assert_eq!(
        tag::<_, &[u8], InputError<_>>(AsciiCaseless('a')).parse_peek(b"ABCxyz"),
        Ok((&b"BCxyz"[..], &b"A"[..]))
    );

    assert_eq!(
        tag::<_, &[u8], InputError<_>>('a').parse_peek(b"ABCxyz"),
        Err(Backtrack(InputError::new(&b"ABCxyz"[..], ErrorKind::Tag)))
    );

    assert_eq!(
        tag::<_, &[u8], InputError<_>>(AsciiCaseless('π')).parse_peek(b"\xCF\x803.14"),
        Ok((&b"3.14"[..], "π".as_bytes()))
    );

    assert_eq!(
        tag::<_, _, InputError<_>>(AsciiCaseless('🧑')).parse_peek("🧑你好"),
        Ok(("你好", "🧑"))
    );

    let mut buffer = [0; 4];
    let input = '\u{241b}'.encode_utf8(&mut buffer);
    assert_eq!(
        tag::<_, &[u8], InputError<_>>(AsciiCaseless('␛')).parse_peek(input.as_bytes()),
        Ok((&b""[..], [226, 144, 155].as_slice()))
    );

    assert_eq!(
        tag::<_, &[u8], InputError<_>>('-').parse_peek(b"\xCF\x80"),
        Err(Backtrack(InputError::new(&b"\xCF\x80"[..], ErrorKind::Tag)))
    );
}