use crate::source::CustomDecoder;

/// Configuration of the parser
pub struct ParserOptions {
    /// Name of the buffer. Used in all diagnostic messages
    pub buffer_name: String,

    /// Controls whether the parser should run in debug mode
    ///
    /// Debug mode forces parser/lexer to print additional information
    /// while running (like bison actions)
    pub debug: bool,

    /// Custom decoder that can be used if the source is encoded
    /// in unknown encoding. Only UTF-8 and ASCII-8BIT/BINARY are
    /// supported out of the box.
    ///
    /// # Example
    /// ```rust
    /// use lib_ruby_parser::source::{InputError, RecognizedEncoding, CustomDecoder};
    /// use lib_ruby_parser::{Parser, ParserOptions, ParserResult};
    ///
    /// fn decode(encoding: RecognizedEncoding, input: &[u8]) -> Result<Vec<u8>, InputError> {
    ///     if let RecognizedEncoding::US_ASCII = encoding {
    ///         // reencode and return Ok(result)
    ///         println!("{:?}", input);
    ///         println!("{:?}", b"# encoding: us-ascii\ndecoded".to_vec());
    ///         return Ok(b"# encoding: us-ascii\ndecoded".to_vec());
    ///     }
    ///     Err(InputError::DecodingError(
    ///         "only us-ascii is supported".to_owned(),
    ///     ))
    /// }
    ///
    /// let decoder = CustomDecoder { f: Some(Box::new(decode)) };
    /// let options = ParserOptions { decoder, debug: true, ..Default::default() };
    /// let mut parser = Parser::new(b"# encoding: us-ascii\n3 + 3", options);
    /// let ParserResult { ast, input, .. } = parser.do_parse();
    ///
    /// assert_eq!(ast.unwrap().expression().source(&input).unwrap(), "decoded".to_owned())
    /// ```
    pub decoder: CustomDecoder,
}

const DEFAULT_BUFFER_NAME: &str = "(eval)";

impl Default for ParserOptions {
    fn default() -> Self {
        Self {
            buffer_name: DEFAULT_BUFFER_NAME.to_owned(),
            debug: false,
            decoder: CustomDecoder { f: None },
        }
    }
}