use crate::{errors::ParseError, stack::{Instruction, Stack}};

pub fn parse(stack: &mut Stack, file_content: &str) {
    for (i, line) in file_content.lines().enumerate() {
        if line.trim().starts_with(';') || line.is_empty() {
            continue;
        }

        let inst_line: String;
        if let Some(comment_index) = line.trim().find(';') {
            inst_line = line.trim().chars().take(comment_index).collect();
        } else {
            inst_line = line.trim().chars().collect();
        }

        let command: [String; 2] = inst_line.split_once(char::is_whitespace)
        .map_or_else(|| [inst_line.trim().to_string(), "".to_string()],
        |(first, second)| [first.trim().to_string(), second.trim().to_string()]);

        let name: String;
        let mut arg: String = String::new();
        let mut data: u16 = 0;

        name = command[0].clone();

        if !command[1].is_empty() {
            if name.chars().nth(0) == Some('#') || name.chars().nth(1) == Some('#') {    
                let splited_data: Vec<String> = command[1].split_whitespace().map(String::from).collect();
                arg = splited_data.get(0).unwrap().clone();
            } else if name.chars().nth(0) == Some('$') || name.chars().nth(1) == Some('$') {
                arg = command[1].clone();
            } else if command[1] == "-1" { // required for
                data = 65535;              // _unix_random
            } else if let Ok(number) = command[1].parse() {
                data = number;
            } else {
                eprintln!("{}", ParseError::ArgumentNotRequired(command[0].to_string(), i + 1, line.to_string()));
                std::process::exit(2);
            }
        }

        let inst = Instruction { name, arg, data };
        stack.program.push(inst);
    }
}