use crate::completion::{CompletionContext, Completions};

/// Completes constats and paths in patterns.
pub(super) fn complete_pattern(acc: &mut Completions, ctx: &CompletionContext) {
    if !ctx.is_pat_binding {
        return;
    }
    // FIXME: ideally, we should look at the type we are matching against and
    // suggest variants + auto-imports
    let names = ctx.analyzer.all_names(ctx.db);
    for (name, res) in names.into_iter() {
        let r = res.as_ref();
        let def = match r.take_types().or_else(|| r.take_values()) {
            Some(hir::Resolution::Def(def)) => def,
            _ => continue,
        };
        match def {
            hir::ModuleDef::Adt(hir::Adt::Enum(..))
            | hir::ModuleDef::EnumVariant(..)
            | hir::ModuleDef::Const(..)
            | hir::ModuleDef::Module(..) => (),
            _ => continue,
        }
        acc.add_resolution(ctx, name.to_string(), &res)
    }
}

#[cfg(test)]
mod tests {
    use crate::completion::{do_completion, CompletionItem, CompletionKind};
    use insta::assert_debug_snapshot;

    fn complete(code: &str) -> Vec<CompletionItem> {
        do_completion(code, CompletionKind::Reference)
    }

    #[test]
    fn completes_enum_variants_and_modules() {
        let completions = complete(
            r"
            enum E { X }
            use self::E::X;
            const Z: E = E::X;
            mod m {}

            static FOO: E = E::X;
            struct Bar { f: u32 }

            fn foo() {
               match E::X {
                   <|>
               }
            }
            ",
        );
        assert_debug_snapshot!(completions, @r###"
       ⋮[
       ⋮    CompletionItem {
       ⋮        label: "E",
       ⋮        source_range: [246; 246),
       ⋮        delete: [246; 246),
       ⋮        insert: "E",
       ⋮        kind: Enum,
       ⋮    },
       ⋮    CompletionItem {
       ⋮        label: "X",
       ⋮        source_range: [246; 246),
       ⋮        delete: [246; 246),
       ⋮        insert: "X",
       ⋮        kind: EnumVariant,
       ⋮    },
       ⋮    CompletionItem {
       ⋮        label: "Z",
       ⋮        source_range: [246; 246),
       ⋮        delete: [246; 246),
       ⋮        insert: "Z",
       ⋮        kind: Const,
       ⋮    },
       ⋮    CompletionItem {
       ⋮        label: "m",
       ⋮        source_range: [246; 246),
       ⋮        delete: [246; 246),
       ⋮        insert: "m",
       ⋮        kind: Module,
       ⋮    },
       ⋮]
        "###);
    }
}