use std::error::Error;
use std::fs;
use std::path::PathBuf;

pub fn normalize(file: PathBuf) -> Result<String, Box<dyn Error>> {
    let file_str = fs::read_to_string(file)?;

    let mut normalized = "; This file has only been normalized. It has not been processed or optimized.\n; This code cannot yet directly be passed into the assembler.\n".to_string();
    normalized += "; t+normalizer:tmCPU t+preprocessor:none t+optimizer:none @generated\n";

    for (line_num, line) in file_str.lines().enumerate() {
        let line_split: Vec<&str> = line.split(' ').collect();

        match line_split[0] {
            "lsh" => {
                if line_split.len() != 3 {
                    return Err(format!("line {}: expected exactly 2 arguments to 'lsh', instead got {}", line_num, line_split.len() - 1).into());
                }
                let dest = line_split[1];
                if !dest.ends_with(',') {
                    return Err(format!("line {}: arg 1 to 'lsh' must end in ','", line_num).into());
                }
                let dest = &dest[..dest.len()-1];
                let rg = line_split[2];

                normalized += &format!("add {}, {} {} ; normalizer: originally '{}'\n", dest, rg, rg, line);

            },
            "cmp" => {
                if line_split.len() != 3 {
                    return Err(format!("line {}: expected exactly 2 arguments to 'cmp', instead got {}", line_num, line_split.len() - 1).into());
                }
                let a = line_split[1];
                let b = line_split[2];

                normalized += &format!("sub r0, {} {} ; normalizer: originally '{}'\n", a, b, line);
            },
            "cpy" => {
                if line_split.len() != 3 {
                    return Err(format!("line {}: expected exactly 2 arguments to 'cpy', instead got {}", line_num, line_split.len() - 1).into());
                }
                let dest = line_split[1];
                let a = line_split[2];

                if !dest.ends_with(',') {
                    return Err(format!("line {}: arg 1 to 'lsh' must end in ','", line_num).into());
                }

                normalized += "ldi r0, 0 ; normalizer: originally below\n";
                normalized += &format!("add {}, {} r0 ; normalizer: originally '{}'\n", &dest[..dest.len()-1], a, line);
            },
            "not" => {
                if line_split.len() != 3 {
                    return Err(format!("line {}: expected exactly 2 arguments to 'not', instead got {}", line_num, line_split.len() - 1).into());
                }
                let dest = line_split[1];
                let a = line_split[2];

                if !dest.ends_with(',') {
                    return Err(format!("line {}: arg 1 to 'not' must end in ','", line_num).into());
                }

                normalized += "ldi r0, 0 ; normalizer: originally below\n";
                normalized += &format!("nor {}, {} r0 ; normalizer: originally '{}'\n", &dest[..dest.len()-1], a, line);
            }
            _ => {
                normalized += line;
                normalized += "\n";
            }
        }
    }

    Ok(normalized)
}