//! Top-level error handling for the Dust language.
use annotate_snippets::{Level, Renderer, Snippet};
use std::fmt::Display;

use crate::{ast::Span, AnalysisError, LexError, ParseError, RuntimeError};

/// An error that occurred during the execution of the Dust language and its
/// corresponding source code.
#[derive(Debug, Clone, PartialEq)]
pub enum DustError<'src> {
    Runtime {
        runtime_error: RuntimeError,
        source: &'src str,
    },
    Analysis {
        analysis_error: AnalysisError,
        source: &'src str,
    },
    Parse {
        parse_error: ParseError,
        source: &'src str,
    },
    Lex {
        lex_error: LexError,
        source: &'src str,
    },
}

impl<'src> DustError<'src> {
    pub fn runtime(runtime_error: RuntimeError, source: &'src str) -> Self {
        DustError::Runtime {
            runtime_error,
            source,
        }
    }

    pub fn analysis(analysis_error: AnalysisError, source: &'src str) -> Self {
        DustError::Analysis {
            analysis_error,
            source,
        }
    }

    pub fn parse(parse_error: ParseError, source: &'src str) -> Self {
        DustError::Parse {
            parse_error,
            source,
        }
    }

    pub fn lex(lex_error: LexError, source: &'src str) -> Self {
        DustError::Lex { lex_error, source }
    }

    pub fn title(&self) -> &'static str {
        match self {
            DustError::Runtime { .. } => "Runtime error",
            DustError::Analysis { .. } => "Analysis error",
            DustError::Parse { .. } => "Parse error",
            DustError::Lex { .. } => "Lex error",
        }
    }

    pub fn position(&self) -> Span {
        match self {
            DustError::Runtime { runtime_error, .. } => runtime_error.position(),
            DustError::Analysis { analysis_error, .. } => analysis_error.position(),
            DustError::Parse { parse_error, .. } => parse_error.position(),
            DustError::Lex { lex_error, .. } => lex_error.position(),
        }
    }

    pub fn source(&self) -> &'src str {
        match self {
            DustError::Runtime { source, .. } => source,
            DustError::Analysis { source, .. } => source,
            DustError::Parse { source, .. } => source,
            DustError::Lex { source, .. } => source,
        }
    }

    pub fn primary_error_data(&self) -> (&'static str, Span, String) {
        (self.title(), self.position(), self.to_string())
    }

    pub fn secondary_error_data(&self) -> Option<(&'static str, Span, String)> {
        if let DustError::Runtime { runtime_error, .. } = self {
            match runtime_error {
                RuntimeError::Expression { error, .. } => {
                    Some(("Expression error", error.position(), error.to_string()))
                }
                RuntimeError::Statement { error, .. } => {
                    Some(("Statement error", error.position(), error.to_string()))
                }
                _ => None,
            }
        } else {
            None
        }
    }

    pub fn report(&self) -> String {
        let mut report = String::new();
        let renderer = Renderer::styled();

        let (title, span, label) = self.primary_error_data();

        let message = Level::Error.title(title).snippet(
            Snippet::source(self.source())
                .annotation(Level::Info.span(span.0..span.1).label(&label)),
        );

        report.push_str(&format!("{}", renderer.render(message)));

        if let Some((title, span, label)) = self.secondary_error_data() {
            let message = Level::Error.title(title).snippet(
                Snippet::source(self.source())
                    .annotation(Level::Info.span(span.0..span.1).label(&label)),
            );

            report.push_str(&format!("{}", renderer.render(message)));
        }

        report
    }
}

impl Display for DustError<'_> {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            DustError::Runtime { runtime_error, .. } => write!(f, "{runtime_error}"),
            DustError::Analysis { analysis_error, .. } => write!(f, "{analysis_error}"),
            DustError::Parse { parse_error, .. } => write!(f, "{parse_error}"),
            DustError::Lex { lex_error, .. } => write!(f, "{lex_error}"),
        }
    }
}