use std::iter;

use hir::AsAssocItem;
use ide_db::helpers::{
    import_assets::{ImportCandidate, LocatedImport},
    mod_path_to_ast,
};
use ide_db::RootDatabase;
use syntax::{
    ast,
    ast::{make, HasArgList},
    AstNode, NodeOrToken,
};

use crate::{
    assist_context::{AssistContext, Assists},
    handlers::auto_import::find_importable_node,
    AssistId, AssistKind, GroupLabel,
};

// Assist: qualify_path
//
// If the name is unresolved, provides all possible qualified paths for it.
//
// ```
// fn main() {
//     let map = HashMap$0::new();
// }
// # pub mod std { pub mod collections { pub struct HashMap { } } }
// ```
// ->
// ```
// fn main() {
//     let map = std::collections::HashMap::new();
// }
// # pub mod std { pub mod collections { pub struct HashMap { } } }
// ```
pub(crate) fn qualify_path(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
    let (import_assets, syntax_under_caret) = find_importable_node(ctx)?;
    let mut proposed_imports = import_assets.search_for_relative_paths(&ctx.sema);
    if proposed_imports.is_empty() {
        return None;
    }

    let range = match &syntax_under_caret {
        NodeOrToken::Node(node) => ctx.sema.original_range(node).range,
        NodeOrToken::Token(token) => token.text_range(),
    };
    let candidate = import_assets.import_candidate();
    let qualify_candidate = match syntax_under_caret {
        NodeOrToken::Node(syntax_under_caret) => match candidate {
            ImportCandidate::Path(candidate) if candidate.qualifier.is_some() => {
                cov_mark::hit!(qualify_path_qualifier_start);
                let path = ast::Path::cast(syntax_under_caret)?;
                let (prev_segment, segment) = (path.qualifier()?.segment()?, path.segment()?);
                QualifyCandidate::QualifierStart(segment, prev_segment.generic_arg_list())
            }
            ImportCandidate::Path(_) => {
                cov_mark::hit!(qualify_path_unqualified_name);
                let path = ast::Path::cast(syntax_under_caret)?;
                let generics = path.segment()?.generic_arg_list();
                QualifyCandidate::UnqualifiedName(generics)
            }
            ImportCandidate::TraitAssocItem(_) => {
                cov_mark::hit!(qualify_path_trait_assoc_item);
                let path = ast::Path::cast(syntax_under_caret)?;
                let (qualifier, segment) = (path.qualifier()?, path.segment()?);
                QualifyCandidate::TraitAssocItem(qualifier, segment)
            }
            ImportCandidate::TraitMethod(_) => {
                cov_mark::hit!(qualify_path_trait_method);
                let mcall_expr = ast::MethodCallExpr::cast(syntax_under_caret)?;
                QualifyCandidate::TraitMethod(ctx.sema.db, mcall_expr)
            }
        },
        // derive attribute path
        NodeOrToken::Token(_) => QualifyCandidate::UnqualifiedName(None),
    };

    // we aren't interested in different namespaces
    proposed_imports.dedup_by(|a, b| a.import_path == b.import_path);

    let group_label = group_label(candidate);
    for import in proposed_imports {
        acc.add_group(
            &group_label,
            AssistId("qualify_path", AssistKind::QuickFix),
            label(candidate, &import),
            range,
            |builder| {
                qualify_candidate.qualify(
                    |replace_with: String| builder.replace(range, replace_with),
                    &import.import_path,
                    import.item_to_import,
                )
            },
        );
    }
    Some(())
}
pub(crate) enum QualifyCandidate<'db> {
    QualifierStart(ast::PathSegment, Option<ast::GenericArgList>),
    UnqualifiedName(Option<ast::GenericArgList>),
    TraitAssocItem(ast::Path, ast::PathSegment),
    TraitMethod(&'db RootDatabase, ast::MethodCallExpr),
    ImplMethod(&'db RootDatabase, ast::MethodCallExpr, hir::Function),
}

impl QualifyCandidate<'_> {
    pub(crate) fn qualify(
        &self,
        mut replacer: impl FnMut(String),
        import: &hir::ModPath,
        item: hir::ItemInNs,
    ) {
        let import = mod_path_to_ast(import);
        match self {
            QualifyCandidate::QualifierStart(segment, generics) => {
                let generics = generics.as_ref().map_or_else(String::new, ToString::to_string);
                replacer(format!("{}{}::{}", import, generics, segment));
            }
            QualifyCandidate::UnqualifiedName(generics) => {
                let generics = generics.as_ref().map_or_else(String::new, ToString::to_string);
                replacer(format!("{}{}", import.to_string(), generics));
            }
            QualifyCandidate::TraitAssocItem(qualifier, segment) => {
                replacer(format!("<{} as {}>::{}", qualifier, import, segment));
            }
            QualifyCandidate::TraitMethod(db, mcall_expr) => {
                Self::qualify_trait_method(db, mcall_expr, replacer, import, item);
            }
            QualifyCandidate::ImplMethod(db, mcall_expr, hir_fn) => {
                Self::qualify_fn_call(db, mcall_expr, replacer, import, hir_fn);
            }
        }
    }

    fn qualify_fn_call(
        db: &RootDatabase,
        mcall_expr: &ast::MethodCallExpr,
        mut replacer: impl FnMut(String),
        import: ast::Path,
        hir_fn: &hir::Function,
    ) -> Option<()> {
        let receiver = mcall_expr.receiver()?;
        let method_name = mcall_expr.name_ref()?;
        let generics =
            mcall_expr.generic_arg_list().as_ref().map_or_else(String::new, ToString::to_string);
        let arg_list = mcall_expr.arg_list().map(|arg_list| arg_list.args());

        if let Some(self_access) = hir_fn.self_param(db).map(|sp| sp.access(db)) {
            let receiver = match self_access {
                hir::Access::Shared => make::expr_ref(receiver, false),
                hir::Access::Exclusive => make::expr_ref(receiver, true),
                hir::Access::Owned => receiver,
            };
            replacer(format!(
                "{}::{}{}{}",
                import,
                method_name,
                generics,
                match arg_list {
                    Some(args) => make::arg_list(iter::once(receiver).chain(args)),
                    None => make::arg_list(iter::once(receiver)),
                }
            ));
        }
        Some(())
    }

    fn qualify_trait_method(
        db: &RootDatabase,
        mcall_expr: &ast::MethodCallExpr,
        replacer: impl FnMut(String),
        import: ast::Path,
        item: hir::ItemInNs,
    ) -> Option<()> {
        let trait_method_name = mcall_expr.name_ref()?;
        let trait_ = item_as_trait(db, item)?;
        let method = find_trait_method(db, trait_, &trait_method_name)?;
        Self::qualify_fn_call(db, mcall_expr, replacer, import, &method)
    }
}

fn find_trait_method(
    db: &RootDatabase,
    trait_: hir::Trait,
    trait_method_name: &ast::NameRef,
) -> Option<hir::Function> {
    if let Some(hir::AssocItem::Function(method)) =
        trait_.items(db).into_iter().find(|item: &hir::AssocItem| {
            item.name(db)
                .map(|name| name.to_string() == trait_method_name.to_string())
                .unwrap_or(false)
        })
    {
        Some(method)
    } else {
        None
    }
}

fn item_as_trait(db: &RootDatabase, item: hir::ItemInNs) -> Option<hir::Trait> {
    let item_module_def = item.as_module_def()?;

    match item_module_def {
        hir::ModuleDef::Trait(trait_) => Some(trait_),
        _ => item_module_def.as_assoc_item(db)?.containing_trait(db),
    }
}

fn group_label(candidate: &ImportCandidate) -> GroupLabel {
    let name = match candidate {
        ImportCandidate::Path(it) => &it.name,
        ImportCandidate::TraitAssocItem(it) | ImportCandidate::TraitMethod(it) => {
            &it.assoc_item_name
        }
    }
    .text();
    GroupLabel(format!("Qualify {}", name))
}

fn label(candidate: &ImportCandidate, import: &LocatedImport) -> String {
    match candidate {
        ImportCandidate::Path(candidate) if candidate.qualifier.is_none() => {
            format!("Qualify as `{}`", import.import_path)
        }
        _ => format!("Qualify with `{}`", import.import_path),
    }
}

#[cfg(test)]
mod tests {
    use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};

    use super::*;

    #[test]
    fn applicable_when_found_an_import_partial() {
        cov_mark::check!(qualify_path_unqualified_name);
        check_assist(
            qualify_path,
            r#"
mod std {
    pub mod fmt {
        pub struct Formatter;
    }
}

use std::fmt;

$0Formatter
"#,
            r#"
mod std {
    pub mod fmt {
        pub struct Formatter;
    }
}

use std::fmt;

fmt::Formatter
"#,
        );
    }

    #[test]
    fn applicable_when_found_an_import() {
        check_assist(
            qualify_path,
            r#"
$0PubStruct

pub mod PubMod {
    pub struct PubStruct;
}
"#,
            r#"
PubMod::PubStruct

pub mod PubMod {
    pub struct PubStruct;
}
"#,
        );
    }

    #[test]
    fn applicable_in_macros() {
        check_assist(
            qualify_path,
            r#"
macro_rules! foo {
    ($i:ident) => { fn foo(a: $i) {} }
}
foo!(Pub$0Struct);

pub mod PubMod {
    pub struct PubStruct;
}
"#,
            r#"
macro_rules! foo {
    ($i:ident) => { fn foo(a: $i) {} }
}
foo!(PubMod::PubStruct);

pub mod PubMod {
    pub struct PubStruct;
}
"#,
        );
    }

    #[test]
    fn applicable_when_found_multiple_imports() {
        check_assist(
            qualify_path,
            r#"
PubSt$0ruct

pub mod PubMod1 {
    pub struct PubStruct;
}
pub mod PubMod2 {
    pub struct PubStruct;
}
pub mod PubMod3 {
    pub struct PubStruct;
}
"#,
            r#"
PubMod3::PubStruct

pub mod PubMod1 {
    pub struct PubStruct;
}
pub mod PubMod2 {
    pub struct PubStruct;
}
pub mod PubMod3 {
    pub struct PubStruct;
}
"#,
        );
    }

    #[test]
    fn not_applicable_for_already_imported_types() {
        check_assist_not_applicable(
            qualify_path,
            r#"
use PubMod::PubStruct;

PubStruct$0

pub mod PubMod {
    pub struct PubStruct;
}
"#,
        );
    }

    #[test]
    fn not_applicable_for_types_with_private_paths() {
        check_assist_not_applicable(
            qualify_path,
            r#"
PrivateStruct$0

pub mod PubMod {
    struct PrivateStruct;
}
"#,
        );
    }

    #[test]
    fn not_applicable_when_no_imports_found() {
        check_assist_not_applicable(qualify_path, r#"PubStruct$0"#);
    }

    #[test]
    fn not_applicable_in_import_statements() {
        check_assist_not_applicable(
            qualify_path,
            r#"
use PubStruct$0;

pub mod PubMod {
    pub struct PubStruct;
}
"#,
        );
    }

    #[test]
    fn qualify_function() {
        check_assist(
            qualify_path,
            r#"
test_function$0

pub mod PubMod {
    pub fn test_function() {};
}
"#,
            r#"
PubMod::test_function

pub mod PubMod {
    pub fn test_function() {};
}
"#,
        );
    }

    #[test]
    fn qualify_macro() {
        check_assist(
            qualify_path,
            r#"
//- /lib.rs crate:crate_with_macro
#[macro_export]
macro_rules! foo {
    () => ()
}

//- /main.rs crate:main deps:crate_with_macro
fn main() {
    foo$0
}
"#,
            r#"
fn main() {
    crate_with_macro::foo
}
"#,
        );
    }

    #[test]
    fn qualify_path_target() {
        check_assist_target(
            qualify_path,
            r#"
struct AssistInfo {
    group_label: Option<$0GroupLabel>,
}

mod m { pub struct GroupLabel; }
"#,
            "GroupLabel",
        )
    }

    #[test]
    fn not_applicable_when_path_start_is_imported() {
        check_assist_not_applicable(
            qualify_path,
            r#"
pub mod mod1 {
    pub mod mod2 {
        pub mod mod3 {
            pub struct TestStruct;
        }
    }
}

use mod1::mod2;
fn main() {
    mod2::mod3::TestStruct$0
}
"#,
        );
    }

    #[test]
    fn not_applicable_for_imported_function() {
        check_assist_not_applicable(
            qualify_path,
            r#"
pub mod test_mod {
    pub fn test_function() {}
}

use test_mod::test_function;
fn main() {
    test_function$0
}
"#,
        );
    }

    #[test]
    fn associated_struct_function() {
        check_assist(
            qualify_path,
            r#"
mod test_mod {
    pub struct TestStruct {}
    impl TestStruct {
        pub fn test_function() {}
    }
}

fn main() {
    TestStruct::test_function$0
}
"#,
            r#"
mod test_mod {
    pub struct TestStruct {}
    impl TestStruct {
        pub fn test_function() {}
    }
}

fn main() {
    test_mod::TestStruct::test_function
}
"#,
        );
    }

    #[test]
    fn associated_struct_const() {
        cov_mark::check!(qualify_path_qualifier_start);
        check_assist(
            qualify_path,
            r#"
mod test_mod {
    pub struct TestStruct {}
    impl TestStruct {
        const TEST_CONST: u8 = 42;
    }
}

fn main() {
    TestStruct::TEST_CONST$0
}
"#,
            r#"
mod test_mod {
    pub struct TestStruct {}
    impl TestStruct {
        const TEST_CONST: u8 = 42;
    }
}

fn main() {
    test_mod::TestStruct::TEST_CONST
}
"#,
        );
    }

    #[test]
    fn associated_struct_const_unqualified() {
        // FIXME: non-trait assoc items completion is unsupported yet, see FIXME in the import_assets.rs for more details
        check_assist_not_applicable(
            qualify_path,
            r#"
mod test_mod {
    pub struct TestStruct {}
    impl TestStruct {
        const TEST_CONST: u8 = 42;
    }
}

fn main() {
    TEST_CONST$0
}
"#,
        );
    }

    #[test]
    fn associated_trait_function() {
        check_assist(
            qualify_path,
            r#"
mod test_mod {
    pub trait TestTrait {
        fn test_function();
    }
    pub struct TestStruct {}
    impl TestTrait for TestStruct {
        fn test_function() {}
    }
}

fn main() {
    test_mod::TestStruct::test_function$0
}
"#,
            r#"
mod test_mod {
    pub trait TestTrait {
        fn test_function();
    }
    pub struct TestStruct {}
    impl TestTrait for TestStruct {
        fn test_function() {}
    }
}

fn main() {
    <test_mod::TestStruct as test_mod::TestTrait>::test_function
}
"#,
        );
    }

    #[test]
    fn not_applicable_for_imported_trait_for_function() {
        check_assist_not_applicable(
            qualify_path,
            r#"
mod test_mod {
    pub trait TestTrait {
        fn test_function();
    }
    pub trait TestTrait2 {
        fn test_function();
    }
    pub enum TestEnum {
        One,
        Two,
    }
    impl TestTrait2 for TestEnum {
        fn test_function() {}
    }
    impl TestTrait for TestEnum {
        fn test_function() {}
    }
}

use test_mod::TestTrait2;
fn main() {
    test_mod::TestEnum::test_function$0;
}
"#,
        )
    }

    #[test]
    fn associated_trait_const() {
        cov_mark::check!(qualify_path_trait_assoc_item);
        check_assist(
            qualify_path,
            r#"
mod test_mod {
    pub trait TestTrait {
        const TEST_CONST: u8;
    }
    pub struct TestStruct {}
    impl TestTrait for TestStruct {
        const TEST_CONST: u8 = 42;
    }
}

fn main() {
    test_mod::TestStruct::TEST_CONST$0
}
"#,
            r#"
mod test_mod {
    pub trait TestTrait {
        const TEST_CONST: u8;
    }
    pub struct TestStruct {}
    impl TestTrait for TestStruct {
        const TEST_CONST: u8 = 42;
    }
}

fn main() {
    <test_mod::TestStruct as test_mod::TestTrait>::TEST_CONST
}
"#,
        );
    }

    #[test]
    fn not_applicable_for_imported_trait_for_const() {
        check_assist_not_applicable(
            qualify_path,
            r#"
mod test_mod {
    pub trait TestTrait {
        const TEST_CONST: u8;
    }
    pub trait TestTrait2 {
        const TEST_CONST: f64;
    }
    pub enum TestEnum {
        One,
        Two,
    }
    impl TestTrait2 for TestEnum {
        const TEST_CONST: f64 = 42.0;
    }
    impl TestTrait for TestEnum {
        const TEST_CONST: u8 = 42;
    }
}

use test_mod::TestTrait2;
fn main() {
    test_mod::TestEnum::TEST_CONST$0;
}
"#,
        )
    }

    #[test]
    fn trait_method() {
        cov_mark::check!(qualify_path_trait_method);
        check_assist(
            qualify_path,
            r#"
mod test_mod {
    pub trait TestTrait {
        fn test_method(&self);
    }
    pub struct TestStruct {}
    impl TestTrait for TestStruct {
        fn test_method(&self) {}
    }
}

fn main() {
    let test_struct = test_mod::TestStruct {};
    test_struct.test_meth$0od()
}
"#,
            r#"
mod test_mod {
    pub trait TestTrait {
        fn test_method(&self);
    }
    pub struct TestStruct {}
    impl TestTrait for TestStruct {
        fn test_method(&self) {}
    }
}

fn main() {
    let test_struct = test_mod::TestStruct {};
    test_mod::TestTrait::test_method(&test_struct)
}
"#,
        );
    }

    #[test]
    fn trait_method_multi_params() {
        check_assist(
            qualify_path,
            r#"
mod test_mod {
    pub trait TestTrait {
        fn test_method(&self, test: i32);
    }
    pub struct TestStruct {}
    impl TestTrait for TestStruct {
        fn test_method(&self, test: i32) {}
    }
}

fn main() {
    let test_struct = test_mod::TestStruct {};
    test_struct.test_meth$0od(42)
}
"#,
            r#"
mod test_mod {
    pub trait TestTrait {
        fn test_method(&self, test: i32);
    }
    pub struct TestStruct {}
    impl TestTrait for TestStruct {
        fn test_method(&self, test: i32) {}
    }
}

fn main() {
    let test_struct = test_mod::TestStruct {};
    test_mod::TestTrait::test_method(&test_struct, 42)
}
"#,
        );
    }

    #[test]
    fn trait_method_consume() {
        check_assist(
            qualify_path,
            r#"
mod test_mod {
    pub trait TestTrait {
        fn test_method(self);
    }
    pub struct TestStruct {}
    impl TestTrait for TestStruct {
        fn test_method(self) {}
    }
}

fn main() {
    let test_struct = test_mod::TestStruct {};
    test_struct.test_meth$0od()
}
"#,
            r#"
mod test_mod {
    pub trait TestTrait {
        fn test_method(self);
    }
    pub struct TestStruct {}
    impl TestTrait for TestStruct {
        fn test_method(self) {}
    }
}

fn main() {
    let test_struct = test_mod::TestStruct {};
    test_mod::TestTrait::test_method(test_struct)
}
"#,
        );
    }

    #[test]
    fn trait_method_cross_crate() {
        check_assist(
            qualify_path,
            r#"
//- /main.rs crate:main deps:dep
fn main() {
    let test_struct = dep::test_mod::TestStruct {};
    test_struct.test_meth$0od()
}
//- /dep.rs crate:dep
pub mod test_mod {
    pub trait TestTrait {
        fn test_method(&self);
    }
    pub struct TestStruct {}
    impl TestTrait for TestStruct {
        fn test_method(&self) {}
    }
}
"#,
            r#"
fn main() {
    let test_struct = dep::test_mod::TestStruct {};
    dep::test_mod::TestTrait::test_method(&test_struct)
}
"#,
        );
    }

    #[test]
    fn assoc_fn_cross_crate() {
        check_assist(
            qualify_path,
            r#"
//- /main.rs crate:main deps:dep
fn main() {
    dep::test_mod::TestStruct::test_func$0tion
}
//- /dep.rs crate:dep
pub mod test_mod {
    pub trait TestTrait {
        fn test_function();
    }
    pub struct TestStruct {}
    impl TestTrait for TestStruct {
        fn test_function() {}
    }
}
"#,
            r#"
fn main() {
    <dep::test_mod::TestStruct as dep::test_mod::TestTrait>::test_function
}
"#,
        );
    }

    #[test]
    fn assoc_const_cross_crate() {
        check_assist(
            qualify_path,
            r#"
//- /main.rs crate:main deps:dep
fn main() {
    dep::test_mod::TestStruct::CONST$0
}
//- /dep.rs crate:dep
pub mod test_mod {
    pub trait TestTrait {
        const CONST: bool;
    }
    pub struct TestStruct {}
    impl TestTrait for TestStruct {
        const CONST: bool = true;
    }
}
"#,
            r#"
fn main() {
    <dep::test_mod::TestStruct as dep::test_mod::TestTrait>::CONST
}
"#,
        );
    }

    #[test]
    fn assoc_fn_as_method_cross_crate() {
        check_assist_not_applicable(
            qualify_path,
            r#"
//- /main.rs crate:main deps:dep
fn main() {
    let test_struct = dep::test_mod::TestStruct {};
    test_struct.test_func$0tion()
}
//- /dep.rs crate:dep
pub mod test_mod {
    pub trait TestTrait {
        fn test_function();
    }
    pub struct TestStruct {}
    impl TestTrait for TestStruct {
        fn test_function() {}
    }
}
"#,
        );
    }

    #[test]
    fn private_trait_cross_crate() {
        check_assist_not_applicable(
            qualify_path,
            r#"
//- /main.rs crate:main deps:dep
fn main() {
    let test_struct = dep::test_mod::TestStruct {};
    test_struct.test_meth$0od()
}
//- /dep.rs crate:dep
pub mod test_mod {
    trait TestTrait {
        fn test_method(&self);
    }
    pub struct TestStruct {}
    impl TestTrait for TestStruct {
        fn test_method(&self) {}
    }
}
"#,
        );
    }

    #[test]
    fn not_applicable_for_imported_trait_for_method() {
        check_assist_not_applicable(
            qualify_path,
            r#"
mod test_mod {
    pub trait TestTrait {
        fn test_method(&self);
    }
    pub trait TestTrait2 {
        fn test_method(&self);
    }
    pub enum TestEnum {
        One,
        Two,
    }
    impl TestTrait2 for TestEnum {
        fn test_method(&self) {}
    }
    impl TestTrait for TestEnum {
        fn test_method(&self) {}
    }
}

use test_mod::TestTrait2;
fn main() {
    let one = test_mod::TestEnum::One;
    one.test$0_method();
}
"#,
        )
    }

    #[test]
    fn dep_import() {
        check_assist(
            qualify_path,
            r"
//- /lib.rs crate:dep
pub struct Struct;

//- /main.rs crate:main deps:dep
fn main() {
    Struct$0
}
",
            r"
fn main() {
    dep::Struct
}
",
        );
    }

    #[test]
    fn whole_segment() {
        // Tests that only imports whose last segment matches the identifier get suggested.
        check_assist(
            qualify_path,
            r"
//- /lib.rs crate:dep
pub mod fmt {
    pub trait Display {}
}

pub fn panic_fmt() {}

//- /main.rs crate:main deps:dep
struct S;

impl f$0mt::Display for S {}
",
            r"
struct S;

impl dep::fmt::Display for S {}
",
        );
    }

    #[test]
    fn macro_generated() {
        // Tests that macro-generated items are suggested from external crates.
        check_assist(
            qualify_path,
            r"
//- /lib.rs crate:dep
macro_rules! mac {
    () => {
        pub struct Cheese;
    };
}

mac!();

//- /main.rs crate:main deps:dep
fn main() {
    Cheese$0;
}
",
            r"
fn main() {
    dep::Cheese;
}
",
        );
    }

    #[test]
    fn casing() {
        // Tests that differently cased names don't interfere and we only suggest the matching one.
        check_assist(
            qualify_path,
            r"
//- /lib.rs crate:dep
pub struct FMT;
pub struct fmt;

//- /main.rs crate:main deps:dep
fn main() {
    FMT$0;
}
",
            r"
fn main() {
    dep::FMT;
}
",
        );
    }

    #[test]
    fn keep_generic_annotations() {
        check_assist(
            qualify_path,
            r"
//- /lib.rs crate:dep
pub mod generic { pub struct Thing<'a, T>(&'a T); }

//- /main.rs crate:main deps:dep
fn foo() -> Thin$0g<'static, ()> {}

fn main() {}
",
            r"
fn foo() -> dep::generic::Thing<'static, ()> {}

fn main() {}
",
        );
    }

    #[test]
    fn keep_generic_annotations_leading_colon() {
        check_assist(
            qualify_path,
            r#"
//- /lib.rs crate:dep
pub mod generic { pub struct Thing<'a, T>(&'a T); }

//- /main.rs crate:main deps:dep
fn foo() -> Thin$0g::<'static, ()> {}

fn main() {}
"#,
            r"
fn foo() -> dep::generic::Thing::<'static, ()> {}

fn main() {}
",
        );
    }

    #[test]
    fn associated_struct_const_generic() {
        check_assist(
            qualify_path,
            r#"
mod test_mod {
    pub struct TestStruct<T> {}
    impl<T> TestStruct<T> {
        const TEST_CONST: u8 = 42;
    }
}

fn main() {
    TestStruct::<()>::TEST_CONST$0
}
"#,
            r#"
mod test_mod {
    pub struct TestStruct<T> {}
    impl<T> TestStruct<T> {
        const TEST_CONST: u8 = 42;
    }
}

fn main() {
    test_mod::TestStruct::<()>::TEST_CONST
}
"#,
        );
    }

    #[test]
    fn associated_trait_const_generic() {
        check_assist(
            qualify_path,
            r#"
mod test_mod {
    pub trait TestTrait {
        const TEST_CONST: u8;
    }
    pub struct TestStruct<T> {}
    impl<T> TestTrait for TestStruct<T> {
        const TEST_CONST: u8 = 42;
    }
}

fn main() {
    test_mod::TestStruct::<()>::TEST_CONST$0
}
"#,
            r#"
mod test_mod {
    pub trait TestTrait {
        const TEST_CONST: u8;
    }
    pub struct TestStruct<T> {}
    impl<T> TestTrait for TestStruct<T> {
        const TEST_CONST: u8 = 42;
    }
}

fn main() {
    <test_mod::TestStruct::<()> as test_mod::TestTrait>::TEST_CONST
}
"#,
        );
    }

    #[test]
    fn trait_method_generic() {
        check_assist(
            qualify_path,
            r#"
mod test_mod {
    pub trait TestTrait {
        fn test_method<T>(&self);
    }
    pub struct TestStruct {}
    impl TestTrait for TestStruct {
        fn test_method<T>(&self) {}
    }
}

fn main() {
    let test_struct = test_mod::TestStruct {};
    test_struct.test_meth$0od::<()>()
}
"#,
            r#"
mod test_mod {
    pub trait TestTrait {
        fn test_method<T>(&self);
    }
    pub struct TestStruct {}
    impl TestTrait for TestStruct {
        fn test_method<T>(&self) {}
    }
}

fn main() {
    let test_struct = test_mod::TestStruct {};
    test_mod::TestTrait::test_method::<()>(&test_struct)
}
"#,
        );
    }

    #[test]
    fn works_in_derives() {
        check_assist(
            qualify_path,
            r#"
//- minicore:derive
mod foo {
    #[rustc_builtin_macro]
    pub macro Copy {}
}
#[derive(Copy$0)]
struct Foo;
"#,
            r#"
mod foo {
    #[rustc_builtin_macro]
    pub macro Copy {}
}
#[derive(foo::Copy)]
struct Foo;
"#,
        );
    }
}