use roc_can::constraint::Constraint::{self, *};
use roc_can::constraint::LetConstraint;
use roc_can::expected::Expected::{self, *};
use roc_collections::all::SendMap;
use roc_module::ident::TagName;
use roc_module::symbol::Symbol;
use roc_region::all::Region;
use roc_types::subs::Variable;
use roc_types::types::Category;
use roc_types::types::Reason;
use roc_types::types::Type::{self, *};

#[inline(always)]
pub fn int_literal(
    num_var: Variable,
    percision_var: Variable,
    expected: Expected<Type>,
    region: Region,
) -> Constraint {
    let num_type = Variable(num_var);
    let reason = Reason::IntLiteral;

    exists(
        vec![num_var],
        And(vec![
            Eq(
                num_type.clone(),
                ForReason(reason, num_int(Type::Variable(percision_var)), region),
                Category::Int,
                region,
            ),
            Eq(num_type, expected, Category::Int, region),
        ]),
    )
}

#[inline(always)]
pub fn float_literal(
    num_var: Variable,
    percision_var: Variable,
    expected: Expected<Type>,
    region: Region,
) -> Constraint {
    let num_type = Variable(num_var);
    let reason = Reason::FloatLiteral;

    exists(
        vec![num_var],
        And(vec![
            Eq(
                num_type.clone(),
                ForReason(reason, num_float(Type::Variable(percision_var)), region),
                Category::Float,
                region,
            ),
            Eq(num_type, expected, Category::Float, region),
        ]),
    )
}

#[inline(always)]
pub fn exists(flex_vars: Vec<Variable>, constraint: Constraint) -> Constraint {
    Let(Box::new(LetConstraint {
        rigid_vars: Vec::new(),
        flex_vars,
        def_types: SendMap::default(),
        defs_constraint: constraint,
        ret_constraint: Constraint::True,
    }))
}

#[inline(always)]
pub fn builtin_type(symbol: Symbol, args: Vec<Type>) -> Type {
    Type::Apply(symbol, args)
}

#[inline(always)]
pub fn empty_list_type(var: Variable) -> Type {
    list_type(Type::Variable(var))
}

#[inline(always)]
pub fn list_type(typ: Type) -> Type {
    builtin_type(Symbol::LIST_LIST, vec![typ])
}

#[inline(always)]
pub fn str_type() -> Type {
    builtin_type(Symbol::STR_STR, Vec::new())
}

#[inline(always)]
pub fn num_float(range: Type) -> Type {
    Type::Alias(
        Symbol::NUM_FLOAT,
        vec![("range".into(), range.clone())],
        Box::new(num_num(num_floatingpoint(range))),
    )
}

#[inline(always)]
pub fn num_floatingpoint(range: Type) -> Type {
    let alias_content = Type::TagUnion(
        vec![(
            TagName::Private(Symbol::NUM_AT_FLOATINGPOINT),
            vec![range.clone()],
        )],
        Box::new(Type::EmptyTagUnion),
    );

    Type::Alias(
        Symbol::NUM_FLOATINGPOINT,
        vec![("range".into(), range)],
        Box::new(alias_content),
    )
}

#[inline(always)]
pub fn num_binary64() -> Type {
    let alias_content = Type::TagUnion(
        vec![(TagName::Private(Symbol::NUM_AT_BINARY64), vec![])],
        Box::new(Type::EmptyTagUnion),
    );

    Type::Alias(Symbol::NUM_BINARY64, vec![], Box::new(alias_content))
}

#[inline(always)]
pub fn num_int(range: Type) -> Type {
    Type::Alias(
        Symbol::NUM_INT,
        vec![("range".into(), range.clone())],
        Box::new(num_num(num_integer(range))),
    )
}

#[inline(always)]
pub fn num_signed64() -> Type {
    let alias_content = Type::TagUnion(
        vec![(TagName::Private(Symbol::NUM_AT_SIGNED64), vec![])],
        Box::new(Type::EmptyTagUnion),
    );

    Type::Alias(Symbol::NUM_SIGNED64, vec![], Box::new(alias_content))
}

#[inline(always)]
pub fn num_integer(range: Type) -> Type {
    let alias_content = Type::TagUnion(
        vec![(
            TagName::Private(Symbol::NUM_AT_INTEGER),
            vec![range.clone()],
        )],
        Box::new(Type::EmptyTagUnion),
    );

    Type::Alias(
        Symbol::NUM_INTEGER,
        vec![("range".into(), range)],
        Box::new(alias_content),
    )
}

#[inline(always)]
pub fn num_num(typ: Type) -> Type {
    let alias_content = Type::TagUnion(
        vec![(TagName::Private(Symbol::NUM_AT_NUM), vec![typ.clone()])],
        Box::new(Type::EmptyTagUnion),
    );

    Type::Alias(
        Symbol::NUM_NUM,
        vec![("range".into(), typ)],
        Box::new(alias_content),
    )
}