use crate::expected::{Expected, PExpected};
use roc_collections::all::SendMap;
use roc_module::symbol::Symbol;
use roc_region::all::{Located, Region};
use roc_types::subs::Variable;
use roc_types::types::{Category, PatternCategory, Type};

#[derive(Debug, Clone, PartialEq)]
pub enum Constraint {
    Eq(Type, Expected<Type>, Category, Region),
    Store(Type, Variable, &'static str, u32),
    Lookup(Symbol, Expected<Type>, Region),
    Pattern(Region, PatternCategory, Type, PExpected<Type>),
    True, // Used for things that always unify, e.g. blanks and runtime errors
    SaveTheEnvironment,
    Let(Box<LetConstraint>),
    And(Vec<Constraint>),
}

#[derive(Debug, Clone, PartialEq)]
pub struct LetConstraint {
    pub rigid_vars: Vec<Variable>,
    pub flex_vars: Vec<Variable>,
    pub def_types: SendMap<Symbol, Located<Type>>,
    pub defs_constraint: Constraint,
    pub ret_constraint: Constraint,
}