use std::fs;
use std::io;

use crate::interpreter::InterpreterState;
use crate::lexer::{LexerInfo, lexical_analysis};
use crate::string::SlsStr;
use crate::errors::{LexerResult, LexerTokenResult};

/// Execute the contents of a script file.
pub fn exec_file(interpreter: &mut InterpreterState, filename: SlsStr) -> bool {
    // Read the whole file
    let source = match fs::read_to_string(&filename.str) {
        Ok(s) => s,
        Err(e) => {
            eprintln!("Cannot read file: {} ({})", filename.str, e);
            return false;
        }
    };

    // Wrap source in SlsStr
    let code = SlsStr::from_string(source);
    let mut lexer_info = LexerInfo::new(filename.clone(), code);

    let result = lexical_analysis(&mut lexer_info);

    match result {
        LexerResult::Error(err) => {
            eprintln!("{}", err.message);
            false
        }

        LexerResult::Ok(mut head) => {
            let mut node = Some(head.as_mut());
            while let Some(tok) = node {
                match tok {
                    LexerTokenResult::Error(err) => {
                        eprintln!("{}", err.message);
                        return false;
                    }
                    LexerTokenResult::Token(token) => {
                        if !interpreter.execute(token) {
                            eprintln!("A runtime error occurred!");
                            return false;
                        }
                        node = None; // No linked list, next handled below
                    }
                    LexerTokenResult::Next(_, next) => {
                        node = next.as_deref_mut();
                    }
                }
            }
            true
        }
    }
}

/// Stand-alone file execution entry point.
pub fn run_file(filename: SlsStr) -> i32 {
    println!("Executing file: {}", filename.str);

    let mut interpreter = match InterpreterState::new() {
        Some(i) => i,
        None => return 1,
    };

    if exec_file(&mut interpreter, filename) {
        0
    } else {
        1
    }
}