use sexp::Sexp;

use crate::error::Error;
use crate::instr::{Cond, Instr};
use crate::parse::parse_instr::parse_instructions;
use crate::parse::sexp_expect::{expect_list, expect_string_atom};
use crate::patches::TryRemove;

pub fn parse_cond_branch(tok: Sexp) -> Result<(Cond, Vec<Instr>), Error> {
    let mut list = expect_list(Some(tok), false)?;
    let kw = expect_string_atom(list.try_remove(0))?;

    if !kw.ends_with('?') {
        return Err(Error::Parse(format!("Condition must end with '?': {}", kw).into()));
    }

    Ok((parse_cond(&kw)?, parse_instructions(list)?))
}

pub fn parse_cond(text: &str) -> Result<Cond, Error> {
    Ok(match text.trim_end_matches('?') {
        "eq" | "=" | "==" => Cond::Equal,
        "ne" | "<>" | "!=" | "≠" => Cond::NotEqual,
        "z" | "0" => Cond::Zero,
        "nz" | "<>0" | "!0" => Cond::NotZero,
        "lt" | "<" => Cond::Lower,
        "le" | "<=" | "≤" => Cond::LowerOrEqual,
        "gt" | ">" => Cond::Greater,
        "ge" | ">=" | "≥" => Cond::GreaterOrEqual,
        "pos" | "+" | ">0" => Cond::Positive,
        "neg" | "-" | "<0" => Cond::Negative,
        "npos" | "!+" | "0-" | "<=0" | "≥0" => Cond::NonPositive,
        "nneg" | "!-" | "0+" | ">=0" | "≤0" => Cond::NonNegative,
        "ov" | "^" => Cond::Overflow,
        "c" => Cond::Carry,
        "nc" | "!c" => Cond::NotCarry,
        "nov" | "!ov" | "!^" => Cond::NotOverflow,
        _ => {
            return Err(Error::Parse(format!("Unknown cond: {}", text).into()));
        }
    })
}