use crate::{
    dispatch_selection_function,
    selection::Selection,
    selection_function,
    selection_functions::types::{SFArguments, SFError, SFResult, get_buffer},
    state::EditorState,
};

selection_function! {
    name: character,
    param_type: usize,
    niladic: |(param, es): (usize, &EditorState)| {
        let buf = get_buffer(es, es.current_buffer_id)?;
        Ok(Selection::Position {
            buffer_id: es.current_buffer_id,
            pos: usize::min(param, buf.max_pos())

        }) },
    monadic_rank0: |_, buffer_id, pos| Ok(Selection::Position {buffer_id, pos}),
    monadic_rank1: |(param, _), buffer_id, int| Ok(
        Selection::Position {buffer_id, pos: usize::min(int.end, *param)}
    )
}

selection_function!(
    name: sequential_character,
    param_type: usize,
    niladic: |_| Err(SFError::NoNiladicForm(";n").into()),
    monadic_rank0: |(param, es), buffer_id, pos| {
        let buf = get_buffer(es, buffer_id)?;
        Ok(Selection::Position {buffer_id, pos: usize::min(pos+*param, buf.max_pos())})
    },
    monadic_rank1: |(param, es), buffer_id, int| {
        let buf = get_buffer(es, buffer_id)?;
        Ok(Selection::Position {buffer_id, pos: usize::min(int.end+*param, buf.max_pos())})
    }
);

selection_function!(
    name: reverse_character,
    param_type: usize,
    niladic: |(param, es): (usize, &EditorState)| {
        let buf = get_buffer(es, es.current_buffer_id)?;
        Ok(Selection::Position {
            buffer_id: es.current_buffer_id,
            pos: if buf.max_pos() < param {
                0
            } else {
                buf.max_pos() - param
            },
        })
    },
    monadic_rank0: |_, buffer_id, pos| Ok(Selection::Position {buffer_id, pos}),
    monadic_rank1: |(param, _), buffer_id, int| Ok(
        Selection::Position {buffer_id, pos: usize::min(int.end, *param)}
    )
);

selection_function!(
    name: sequential_reverse_character,
    param_type: usize,
    niladic: |_| Err(SFError::NoNiladicForm(";'n").into()),
    monadic_rank0: |(param, _), buffer_id, pos| {
        Ok(Selection::Position {buffer_id, pos: if *param<pos {pos - *param} else {0}})
    },
    monadic_rank1: |(param, _), buffer_id, int| {
        Ok(Selection::Position {buffer_id, pos: if *param<int.end {int.end - *param} else {0}})
    }
);

selection_function!(
    name: reverse_sequential_character,
    param_type: usize,
    niladic: |_| Err(SFError::NoNiladicForm("';n").into()),
    monadic_rank0: |(param, _), buffer_id, pos| {
        Ok(Selection::Position {buffer_id, pos: if *param<pos {pos - *param} else {0}})
    },
    monadic_rank1: |(param, _), buffer_id, int| {
        Ok(Selection::Position {buffer_id, pos: if *param<int.start {int.start - *param} else {0}})
    }
);

dispatch_selection_function!(
    name: selection_function_character,
    param_type: usize,
    base: character,
    sequential: sequential_character,
    reverse: reverse_character,
    sequential_reverse: sequential_reverse_character,
    reverse_sequential: reverse_sequential_character,
);