use anyhow::bail;
use codespan_reporting::{
    diagnostic::{Diagnostic, Label},
    files::SimpleFiles,
    term::{
        emit,
        termcolor::{ColorChoice, StandardStream},
    },
};
use lalrpop_util::{lexer::Token, ParseError};

pub trait SpannedErr {
    // TODO: Give these a default, so that &str can be used as default.
    fn lo(&self) -> usize;
    fn hi(&self) -> usize;
    // TODO: Allow more controll
    fn message(&self) -> String;
}

pub fn report_error<T, E: SpannedErr>(
    tree: Result<T, ParseError<usize, Token, E>>,
    file_name: &str,
    file_contents: &str,
) -> anyhow::Result<T> {
    match tree {
        Ok(x) => Ok(x),
        Err(e) => {
            let mut err_files = SimpleFiles::new();
            let err_writer = StandardStream::stderr(ColorChoice::Auto);
            let err_config = codespan_reporting::term::Config::default();

            let main_file_id = err_files.add(file_name, file_contents);
            let emit_err = |d| emit(&mut err_writer.lock(), &err_config, &err_files, d);

            let err = match e {
                ParseError::InvalidToken { location } => Diagnostic::error()
                    .with_message("Invalid token")
                    .with_labels(vec![Label::primary(main_file_id, location..location + 1)]),
                ParseError::UnrecognizedEOF { location, expected } => Diagnostic::error()
                    .with_message("Unexpected end of file")
                    .with_labels(vec![Label::primary(main_file_id, location..location + 1)])
                    .with_notes(expected.iter().map(|e| format!("Expected {}", e)).collect()),
                ParseError::UnrecognizedToken { token, expected } => Diagnostic::error()
                    .with_message("Unrecognized token")
                    .with_labels(vec![Label::primary(main_file_id, token.0..token.2)])
                    .with_notes(expected.iter().map(|e| format!("Expected {}", e)).collect()),
                ParseError::ExtraToken { token } => Diagnostic::error()
                    .with_message("Extra token")
                    .with_labels(vec![Label::primary(main_file_id, token.0..token.2)]),
                ParseError::User { error } => Diagnostic::error()
                    .with_message(error.message())
                    .with_labels(vec![Label::primary(main_file_id, error.lo()..error.hi())]),
            };

            emit_err(&err)?;

            bail!("Parse error");
        }
    }
}