mod backend;
mod frontend;
mod logging;
mod prompt;
mod result;

use crate::{
    backend::{
        environment::Environment,
        interpreter::{EvaluateInterpreter, Interpreter},
    },
    frontend::{
        lexer::Lexer,
        parser::Parser,
        source_registry::{SourceFile, SourceId, SourcePosition, SourceRegistry, SourceSlice},
    },
    prompt::prompt_lines,
    result::{LoxError, LoxResult},
};
use std::fs;
use std::{env, error::Error};

fn main() -> LoxResult<()> {
    let args: Vec<String> = env::args().collect();
    let mut lox = LoxInterpreter::new();

    if args.len() > 2 {
        eprintln!("Usage: {} [script]", args[0]);
        std::process::exit(64);
    } else if args.len() == 2 {
        // Esegui file
        lox.run_file(&args[1])?;
    } else {
        // Modalità interattiva
        lox.run_prompt()?;
    }

    Ok(())
}

struct LoxInterpreter {
    source_registry: SourceRegistry,
}

impl LoxInterpreter {
    pub fn new() -> Self {
        LoxInterpreter {
            source_registry: SourceRegistry::new(),
        }
    }

    // ✅ Pipeline funzionale per file
    fn run_file(&mut self, path: &str) -> LoxResult<()> {
        fs::read_to_string(path)
            .map_err(|e| LoxError::IoError {
                message: e.to_string(),
            })
            .and_then(|source| self.source_registry.add_source_string(source))
            .and_then(|source_id| self.process_source(source_id))
            .map(|result| println!("file {}", result))
    }

    // ✅ Pipeline funzionale per prompt
    fn run_prompt(&mut self) -> LoxResult<()> {
        println!("Lox REPL - Type 'exit' to quit");

        prompt_lines(|source| self.source_registry.add_source_string(source))
            .for_each(|line| println!("hi: {}", line));

        Ok(())
    }

    fn process_source(&self, source_id: SourceId) -> LoxResult<String> {
        let mut lexer = Lexer::new(
            self.source_registry.get_by_id(source_id).content.clone(),
            source_id,
        );
        let res = lexer
            .scans_tokens()
            .and_then(|tokens| Parser::new(tokens).parse())
            .and_then(|asts| {
                // println!("asts: {:?}", asts);
                Ok(asts)
            })
            .and_then(|stmts| {
                let mut env = Environment::new();
                let mut interpreter = Interpreter::new(&mut env);
                let mut result = None;
                for stmt in stmts {
                    result = Some(interpreter.interpret(stmt)?);
                }
                match result {
                    Some(res) => Ok(res),
                    _ => Err(LoxError::RuntimeError {
                        source_slice: SourceSlice::default(),
                        message: "what?????".to_string(),
                    }),
                }
            })
            .and_then(|result| Ok(format!("{}", result)))
            .or_else(|err| {
                err.print_with_context(&self.source_registry);
                Err(err)
            });
        // println!("result {}", res);

        res
    }
}