use itertools::Itertools;
use rlox2_frontend::lexer::LexerError;
use rlox2_frontend::parser::{BinaryOp, ParserError, UnaryOp};
use thiserror::Error;

use crate::ResolverError;
use crate::Value;

#[derive(Error, Debug)]
pub enum RuntimeError {
    #[error("Unary operator {op} had invalid argument {arg}")]
    UnaryOpInvalidArgument { op: UnaryOp, arg: Value },
    #[error("Binary operator {op} had invalid arguments {left} and {right}")]
    BinaryOpInvalidArguments { left: Value, op: BinaryOp, right: Value },
    #[error("Division by zero")]
    DivisionByZero,
    #[error("Name {name} is not defined")]
    NameNotDefined { name: String },
    #[error("Global {name} is not defined")]
    GlobalNotDefined { name: String },
    #[error("{callee} is not callable")]
    NotCallable { callee: Value },
    #[error("{name}() takes {arity} args, but {given} were given.")]
    WrongArity { name: String, arity: usize, given: usize },
    #[error("Extern function call to {name} failed: {msg}")]
    ExtFunCallFailed { name: String, msg: String },
    #[error("Uncaught break statement")]
    Break,
    #[error("Uncaught return statement")]
    Return { value: Value },
    #[error("Exit with exit code {exit_code}")]
    Exit { exit_code: i32 },
}

#[derive(Error, Debug)]
#[allow(clippy::enum_variant_names)]
pub enum LoxError {
    #[error("{0}", format_multiple_errors(inner))]
    LexerError { inner: Vec<LexerError> },
    #[error("{0}", format_multiple_errors(inner))]
    ParserError { inner: Vec<ParserError> },
    #[error("{inner}")]
    ResolverError { inner: ResolverError },
    #[error("{inner}")]
    RuntimeError { inner: RuntimeError },
    #[error("Called exit() with exit code {exit_code}")]
    Exit { exit_code: i32 },
}

fn format_multiple_errors(errs: &Vec<impl std::error::Error>) -> String {
    let msg = if errs.len() == 1 {
        errs[0].to_string()
    } else {
        errs.iter().map(|err| err.to_string()).join("\n")
    };

    msg
}

impl From<Vec<LexerError>> for LoxError {
    fn from(lexer_errs: Vec<LexerError>) -> Self {
        LoxError::LexerError { inner: lexer_errs }
    }
}

impl From<Vec<ParserError>> for LoxError {
    fn from(parser_errs: Vec<ParserError>) -> Self {
        LoxError::ParserError { inner: parser_errs }
    }
}

impl From<ResolverError> for LoxError {
    fn from(resolver_err: ResolverError) -> Self {
        LoxError::ResolverError { inner: resolver_err }
    }
}

impl From<RuntimeError> for LoxError {
    fn from(runtime_err: RuntimeError) -> Self {
        match runtime_err {
            RuntimeError::Exit { exit_code } => LoxError::Exit { exit_code },
            _ => LoxError::RuntimeError { inner: runtime_err },
        }
    }
}