use luaur_ast::records::position::Position;

pub(crate) fn get_document_offsets(
    src: &str,
    start_pos: &Position,
    end_pos: &Position,
) -> (usize, usize) {
    let mut line_count: u32 = 0;
    let mut col_count: u32 = 0;

    let mut doc_offset: usize = 0;
    let mut start_offset: usize = 0;
    let mut end_offset: usize = 0;
    let mut found_start = false;
    let mut found_end = false;

    for c in src.chars() {
        if found_start && found_end {
            break;
        }

        if start_pos.line == line_count && start_pos.column == col_count {
            found_start = true;
            start_offset = doc_offset;
        }

        if end_pos.line == line_count && end_pos.column == col_count {
            end_offset = doc_offset;
            found_end = true;
        }

        // We put a cursor position that extends beyond the extents of the current line
        if found_start && !found_end && (line_count > end_pos.line) {
            found_end = true;
            end_offset = doc_offset.saturating_sub(1);
        }

        if c == '\n' {
            line_count += 1;
            col_count = 0;
        } else {
            col_count += 1;
        }
        doc_offset += c.len_utf8();
    }

    if found_start && !found_end {
        end_offset = src.len();
    }

    let min = core::cmp::min(start_offset, end_offset);
    let max = core::cmp::max(start_offset, end_offset);
    let len = max - min;

    (min, len)
}
