mumu-string 0.1.0

use mumu::parser::types::Value;
use crate::common::{is_placeholder, make_three_arg_partial};

pub fn string_slice_bridge(_interp: &mut mumu::parser::interpreter::Interpreter, args: Vec<Value>) -> Result<Value, String> {
    match args.len() {
        0 => Ok(make_three_arg_partial(string_slice_finalize, None, None, None)),
        1 => Ok(make_three_arg_partial(string_slice_finalize, Some(args[0].clone()), None, None)),
        2 => Ok(make_three_arg_partial(string_slice_finalize, Some(args[0].clone()), Some(args[1].clone()), None)),
        3 => {
            let s = &args[0];
            let start = &args[1];
            let end = &args[2];
            let s_pl = is_placeholder(s);
            let start_pl = is_placeholder(start);
            let end_pl = is_placeholder(end);
            if !s_pl && !start_pl && !end_pl {
                string_slice_finalize(vec![s.clone(), start.clone(), end.clone()])
            } else {
                Ok(make_three_arg_partial(
                    string_slice_finalize,
                    if s_pl { None } else { Some(s.clone()) },
                    if start_pl { None } else { Some(start.clone()) },
                    if end_pl { None } else { Some(end.clone()) },
                ))
            }
        }
        n => Err(format!("string:slice => expected up to 3 arguments, got {}", n)),
    }
}

fn string_slice_finalize(mut args: Vec<Value>) -> Result<Value, String> {
    if args.len() != 3 {
        return Err(format!("string:slice => finalize => expected 3 real args, got {}", args.len()));
    }
    let s_val = args.remove(0);
    let start_val = args.remove(0);
    let end_val = args.remove(0);
    let s = match s_val {
        Value::SingleString(s) => s,
        Value::StrArray(ss) if ss.len() == 1 => ss[0].clone(),
        other => return Err(format!("string:slice => first arg must be a string, got {:?}", other)),
    };
    let start = match start_val {
        Value::Int(i) => i,
        other => return Err(format!("string:slice => start must be int, got {:?}", other)),
    };
    let end = match end_val {
        Value::Int(i) => i,
        other => return Err(format!("string:slice => end must be int, got {:?}", other)),
    };
    let len = s.chars().count() as i32;
    let start = if start < 0 { len + start } else { start };
    let end = if end < 0 { len + end } else { end };
    let start = start.max(0).min(len);
    let end = end.max(0).min(len);
    let res: String = s.chars().skip(start as usize).take((end - start).max(0) as usize).collect();
    Ok(Value::SingleString(res))
}