//! The type system. We currently use this to infer types for completion, hover
//! information and various assists.
#[allow(unused)]
macro_rules! eprintln {
    ($($tt:tt)*) => { stdx::eprintln!($($tt)*) };
}

mod autoderef;
pub mod primitive;
pub mod traits;
pub mod method_resolution;
mod op;
mod lower;
pub(crate) mod infer;
pub(crate) mod utils;
mod chalk_cast;
mod chalk_ext;
mod builder;
mod walk;
mod types;

pub mod display;
pub mod db;
pub mod diagnostics;

#[cfg(test)]
mod tests;
#[cfg(test)]
mod test_db;

use std::sync::Arc;

use base_db::salsa;
use chalk_ir::UintTy;
use hir_def::{
    expr::ExprId, type_ref::Rawness, ConstParamId, LifetimeParamId, TraitId, TypeAliasId,
    TypeParamId,
};

use crate::{db::HirDatabase, display::HirDisplay, utils::generics};

pub use autoderef::autoderef;
pub use builder::TyBuilder;
pub use chalk_ext::{ProjectionTyExt, TyExt};
pub use infer::{could_unify, InferenceResult};
pub use lower::{
    associated_type_shorthand_candidates, callable_item_sig, CallableDefId, ImplTraitLoweringMode,
    TyDefId, TyLoweringContext, ValueTyDefId,
};
pub use traits::{chalk::Interner, TraitEnvironment};
pub use types::*;
pub use walk::TypeWalk;

pub use chalk_ir::{
    cast::Cast, AdtId, BoundVar, DebruijnIndex, Mutability, Safety, Scalar, TyVariableKind,
};

pub type ForeignDefId = chalk_ir::ForeignDefId<Interner>;
pub type AssocTypeId = chalk_ir::AssocTypeId<Interner>;
pub type FnDefId = chalk_ir::FnDefId<Interner>;
pub type ClosureId = chalk_ir::ClosureId<Interner>;
pub type OpaqueTyId = chalk_ir::OpaqueTyId<Interner>;
pub type PlaceholderIndex = chalk_ir::PlaceholderIndex;

pub type VariableKind = chalk_ir::VariableKind<Interner>;
pub type VariableKinds = chalk_ir::VariableKinds<Interner>;
pub type CanonicalVarKinds = chalk_ir::CanonicalVarKinds<Interner>;

pub type Lifetime = chalk_ir::Lifetime<Interner>;
pub type LifetimeData = chalk_ir::LifetimeData<Interner>;
pub type LifetimeOutlives = chalk_ir::LifetimeOutlives<Interner>;

pub type Const = chalk_ir::Const<Interner>;
pub type ConstData = chalk_ir::ConstData<Interner>;
pub type ConstValue = chalk_ir::ConstValue<Interner>;
pub type ConcreteConst = chalk_ir::ConcreteConst<Interner>;

pub type ChalkTraitId = chalk_ir::TraitId<Interner>;

pub type FnSig = chalk_ir::FnSig<Interner>;

// FIXME: get rid of this
pub fn subst_prefix(s: &Substitution, n: usize) -> Substitution {
    Substitution::intern(s.interned()[..std::cmp::min(s.len(&Interner), n)].into())
}

/// Return an index of a parameter in the generic type parameter list by it's id.
pub fn param_idx(db: &dyn HirDatabase, id: TypeParamId) -> Option<usize> {
    generics(db.upcast(), id.parent).param_idx(id)
}

pub fn wrap_empty_binders<T>(value: T) -> Binders<T>
where
    T: TypeWalk,
{
    Binders::empty(&Interner, value.shifted_in_from(DebruijnIndex::ONE))
}

pub fn make_only_type_binders<T>(num_vars: usize, value: T) -> Binders<T> {
    Binders::new(
        VariableKinds::from_iter(
            &Interner,
            std::iter::repeat(chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General))
                .take(num_vars),
        ),
        value,
    )
}

impl TraitRef {
    pub fn hir_trait_id(&self) -> TraitId {
        from_chalk_trait_id(self.trait_id)
    }
}

impl<T> Canonical<T> {
    pub fn new(value: T, kinds: impl IntoIterator<Item = TyVariableKind>) -> Self {
        let kinds = kinds.into_iter().map(|tk| {
            chalk_ir::CanonicalVarKind::new(
                chalk_ir::VariableKind::Ty(tk),
                chalk_ir::UniverseIndex::ROOT,
            )
        });
        Self { value, binders: chalk_ir::CanonicalVarKinds::from_iter(&Interner, kinds) }
    }
}

/// A function signature as seen by type inference: Several parameter types and
/// one return type.
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct CallableSig {
    params_and_return: Arc<[Ty]>,
    is_varargs: bool,
}

/// A polymorphic function signature.
pub type PolyFnSig = Binders<CallableSig>;

impl CallableSig {
    pub fn from_params_and_return(mut params: Vec<Ty>, ret: Ty, is_varargs: bool) -> CallableSig {
        params.push(ret);
        CallableSig { params_and_return: params.into(), is_varargs }
    }

    pub fn from_fn_ptr(fn_ptr: &FnPointer) -> CallableSig {
        CallableSig {
            // FIXME: what to do about lifetime params? -> return PolyFnSig
            params_and_return: fn_ptr
                .substitution
                .clone()
                .shifted_out_to(DebruijnIndex::ONE)
                .expect("unexpected lifetime vars in fn ptr")
                .0
                .interned()
                .iter()
                .map(|arg| arg.assert_ty_ref(&Interner).clone())
                .collect(),
            is_varargs: fn_ptr.sig.variadic,
        }
    }

    pub fn params(&self) -> &[Ty] {
        &self.params_and_return[0..self.params_and_return.len() - 1]
    }

    pub fn ret(&self) -> &Ty {
        &self.params_and_return[self.params_and_return.len() - 1]
    }
}

impl Ty {
    pub fn equals_ctor(&self, other: &Ty) -> bool {
        match (self.kind(&Interner), other.kind(&Interner)) {
            (TyKind::Adt(adt, ..), TyKind::Adt(adt2, ..)) => adt == adt2,
            (TyKind::Slice(_), TyKind::Slice(_)) | (TyKind::Array(_, _), TyKind::Array(_, _)) => {
                true
            }
            (TyKind::FnDef(def_id, ..), TyKind::FnDef(def_id2, ..)) => def_id == def_id2,
            (TyKind::OpaqueType(ty_id, ..), TyKind::OpaqueType(ty_id2, ..)) => ty_id == ty_id2,
            (TyKind::AssociatedType(ty_id, ..), TyKind::AssociatedType(ty_id2, ..)) => {
                ty_id == ty_id2
            }
            (TyKind::Foreign(ty_id, ..), TyKind::Foreign(ty_id2, ..)) => ty_id == ty_id2,
            (TyKind::Closure(id1, _), TyKind::Closure(id2, _)) => id1 == id2,
            (TyKind::Ref(mutability, ..), TyKind::Ref(mutability2, ..))
            | (TyKind::Raw(mutability, ..), TyKind::Raw(mutability2, ..)) => {
                mutability == mutability2
            }
            (
                TyKind::Function(FnPointer { num_binders, sig, .. }),
                TyKind::Function(FnPointer { num_binders: num_binders2, sig: sig2, .. }),
            ) => num_binders == num_binders2 && sig == sig2,
            (TyKind::Tuple(cardinality, _), TyKind::Tuple(cardinality2, _)) => {
                cardinality == cardinality2
            }
            (TyKind::Str, TyKind::Str) | (TyKind::Never, TyKind::Never) => true,
            (TyKind::Scalar(scalar), TyKind::Scalar(scalar2)) => scalar == scalar2,
            _ => false,
        }
    }
}

#[derive(Copy, Clone, PartialEq, Eq, Debug, Hash)]
pub enum ImplTraitId {
    ReturnTypeImplTrait(hir_def::FunctionId, u16),
    AsyncBlockTypeImplTrait(hir_def::DefWithBodyId, ExprId),
}

#[derive(Clone, PartialEq, Eq, Debug, Hash)]
pub struct ReturnTypeImplTraits {
    pub(crate) impl_traits: Vec<ReturnTypeImplTrait>,
}

#[derive(Clone, PartialEq, Eq, Debug, Hash)]
pub(crate) struct ReturnTypeImplTrait {
    pub(crate) bounds: Binders<Vec<QuantifiedWhereClause>>,
}

pub fn to_foreign_def_id(id: TypeAliasId) -> ForeignDefId {
    chalk_ir::ForeignDefId(salsa::InternKey::as_intern_id(&id))
}

pub fn from_foreign_def_id(id: ForeignDefId) -> TypeAliasId {
    salsa::InternKey::from_intern_id(id.0)
}

pub fn to_assoc_type_id(id: TypeAliasId) -> AssocTypeId {
    chalk_ir::AssocTypeId(salsa::InternKey::as_intern_id(&id))
}

pub fn from_assoc_type_id(id: AssocTypeId) -> TypeAliasId {
    salsa::InternKey::from_intern_id(id.0)
}

pub fn from_placeholder_idx(db: &dyn HirDatabase, idx: PlaceholderIndex) -> TypeParamId {
    assert_eq!(idx.ui, chalk_ir::UniverseIndex::ROOT);
    let interned_id = salsa::InternKey::from_intern_id(salsa::InternId::from(idx.idx));
    db.lookup_intern_type_param_id(interned_id)
}

pub fn to_placeholder_idx(db: &dyn HirDatabase, id: TypeParamId) -> PlaceholderIndex {
    let interned_id = db.intern_type_param_id(id);
    PlaceholderIndex {
        ui: chalk_ir::UniverseIndex::ROOT,
        idx: salsa::InternKey::as_intern_id(&interned_id).as_usize(),
    }
}

pub fn lt_from_placeholder_idx(db: &dyn HirDatabase, idx: PlaceholderIndex) -> LifetimeParamId {
    assert_eq!(idx.ui, chalk_ir::UniverseIndex::ROOT);
    let interned_id = salsa::InternKey::from_intern_id(salsa::InternId::from(idx.idx));
    db.lookup_intern_lifetime_param_id(interned_id)
}

pub fn const_from_placeholder_idx(db: &dyn HirDatabase, idx: PlaceholderIndex) -> ConstParamId {
    assert_eq!(idx.ui, chalk_ir::UniverseIndex::ROOT);
    let interned_id = salsa::InternKey::from_intern_id(salsa::InternId::from(idx.idx));
    db.lookup_intern_const_param_id(interned_id)
}

pub fn to_chalk_trait_id(id: TraitId) -> ChalkTraitId {
    chalk_ir::TraitId(salsa::InternKey::as_intern_id(&id))
}

pub fn from_chalk_trait_id(id: ChalkTraitId) -> TraitId {
    salsa::InternKey::from_intern_id(id.0)
}

pub fn static_lifetime() -> Lifetime {
    LifetimeData::Static.intern(&Interner)
}

pub fn dummy_usize_const() -> Const {
    let usize_ty = chalk_ir::TyKind::Scalar(Scalar::Uint(UintTy::Usize)).intern(&Interner);
    chalk_ir::ConstData {
        ty: usize_ty,
        value: chalk_ir::ConstValue::Concrete(chalk_ir::ConcreteConst { interned: () }),
    }
    .intern(&Interner)
}