use hir::{Ty, AdtDef, TypeCtor};

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

/// Complete dot accesses, i.e. fields or methods (currently only fields).
pub(super) fn complete_dot(acc: &mut Completions, ctx: &CompletionContext) {
    let receiver_ty = match ctx.dot_receiver.and_then(|it| ctx.analyzer.type_of(ctx.db, it)) {
        Some(it) => it,
        None => return,
    };
    if !ctx.is_call {
        complete_fields(acc, ctx, receiver_ty.clone());
    }
    complete_methods(acc, ctx, receiver_ty);
}

fn complete_fields(acc: &mut Completions, ctx: &CompletionContext, receiver: Ty) {
    for receiver in receiver.autoderef(ctx.db) {
        match receiver {
            Ty::Apply(a_ty) => match a_ty.ctor {
                TypeCtor::Adt(AdtDef::Struct(s)) => {
                    for field in s.fields(ctx.db) {
                        acc.add_field(ctx, field, &a_ty.parameters);
                    }
                }
                // FIXME unions
                TypeCtor::Tuple { .. } => {
                    for (i, ty) in a_ty.parameters.iter().enumerate() {
                        acc.add_pos_field(ctx, i, ty);
                    }
                }
                _ => {}
            },
            _ => {}
        };
    }
}

fn complete_methods(acc: &mut Completions, ctx: &CompletionContext, receiver: Ty) {
    ctx.analyzer.iterate_method_candidates(ctx.db, receiver, None, |_ty, func| {
        let sig = func.signature(ctx.db);
        if sig.has_self_param() {
            acc.add_function(ctx, func);
        }
        None::<()>
    });
}

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

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

    #[test]
    fn test_struct_field_completion() {
        assert_debug_snapshot_matches!(
        do_ref_completion(
                r"
                struct A { the_field: u32 }
                fn foo(a: A) {
                a.<|>
                }
                ",
        ),
            @r###"[
    CompletionItem {
        label: "the_field",
        source_range: [94; 94),
        delete: [94; 94),
        insert: "the_field",
        kind: Field,
        detail: "u32"
    }
]"###
        );
    }

    #[test]
    fn test_struct_field_completion_self() {
        assert_debug_snapshot_matches!(
        do_ref_completion(
            r"
            struct A {
                /// This is the_field
                the_field: (u32,)
            }
            impl A {
                fn foo(self) {
                    self.<|>
                }
            }
            ",
        ),
        @r###"[
    CompletionItem {
        label: "foo",
        source_range: [187; 187),
        delete: [187; 187),
        insert: "foo()$0",
        kind: Method,
        detail: "fn foo(self)"
    },
    CompletionItem {
        label: "the_field",
        source_range: [187; 187),
        delete: [187; 187),
        insert: "the_field",
        kind: Field,
        detail: "(u32,)",
        documentation: Documentation(
            "This is the_field"
        )
    }
]"###
        );
    }

    #[test]
    fn test_struct_field_completion_autoderef() {
        assert_debug_snapshot_matches!(
        do_ref_completion(
            r"
            struct A { the_field: (u32, i32) }
            impl A {
                fn foo(&self) {
                    self.<|>
                }
            }
            ",
        ),
        @r###"[
    CompletionItem {
        label: "foo",
        source_range: [126; 126),
        delete: [126; 126),
        insert: "foo()$0",
        kind: Method,
        detail: "fn foo(&self)"
    },
    CompletionItem {
        label: "the_field",
        source_range: [126; 126),
        delete: [126; 126),
        insert: "the_field",
        kind: Field,
        detail: "(u32, i32)"
    }
]"###
        );
    }

    #[test]
    fn test_no_struct_field_completion_for_method_call() {
        assert_debug_snapshot_matches!(
        do_ref_completion(
            r"
            struct A { the_field: u32 }
            fn foo(a: A) {
               a.<|>()
            }
            ",
        ),
        @"[]"
        );
    }

    #[test]
    fn test_method_completion() {
        assert_debug_snapshot_matches!(
        do_ref_completion(
            r"
            struct A {}
            impl A {
                fn the_method(&self) {}
            }
            fn foo(a: A) {
               a.<|>
            }
            ",
        ),
        @r###"[
    CompletionItem {
        label: "the_method",
        source_range: [144; 144),
        delete: [144; 144),
        insert: "the_method()$0",
        kind: Method,
        detail: "fn the_method(&self)"
    }
]"###
        );
    }

    #[test]
    fn test_trait_method_completion() {
        assert_debug_snapshot_matches!(
            do_ref_completion(
                r"
            struct A {}
            trait Trait { fn the_method(&self); }
            impl Trait for A {}
            fn foo(a: A) {
               a.<|>
            }
            ",
            ),
            @r###"[
    CompletionItem {
        label: "the_method",
        source_range: [151; 151),
        delete: [151; 151),
        insert: "the_method()$0",
        kind: Method,
        detail: "fn the_method(&self)"
    }
]"###
        );
    }

    #[test]
    fn test_no_non_self_method() {
        assert_debug_snapshot_matches!(
        do_ref_completion(
            r"
            struct A {}
            impl A {
                fn the_method() {}
            }
            fn foo(a: A) {
               a.<|>
            }
            ",
        ),
        @"[]"
        );
    }

    #[test]
    fn test_method_attr_filtering() {
        assert_debug_snapshot_matches!(
        do_ref_completion(
            r"
            struct A {}
            impl A {
                #[inline]
                fn the_method(&self) {
                    let x = 1;
                    let y = 2;
                }
            }
            fn foo(a: A) {
               a.<|>
            }
            ",
        ),
        @r###"[
    CompletionItem {
        label: "the_method",
        source_range: [249; 249),
        delete: [249; 249),
        insert: "the_method()$0",
        kind: Method,
        detail: "fn the_method(&self)"
    }
]"###
        );
    }

    #[test]
    fn test_tuple_field_completion() {
        assert_debug_snapshot_matches!(
        do_ref_completion(
            r"
            fn foo() {
               let b = (0, 3.14);
               b.<|>
            }
            ",
        ),
        @r###"[
    CompletionItem {
        label: "0",
        source_range: [75; 75),
        delete: [75; 75),
        insert: "0",
        kind: Field,
        detail: "i32"
    },
    CompletionItem {
        label: "1",
        source_range: [75; 75),
        delete: [75; 75),
        insert: "1",
        kind: Field,
        detail: "f64"
    }
]"###
        );
    }

    #[test]
    fn test_tuple_field_inference() {
        assert_debug_snapshot_matches!(
        do_ref_completion(
            r"
            pub struct S;
            impl S {
                pub fn blah(&self) {}
            }

            struct T(S);

            impl T {
                fn foo(&self) {
                    // FIXME: This doesn't work without the trailing `a` as `0.` is a float
                    self.0.a<|>
                }
            }
            ",
        ),
        @r###"[
    CompletionItem {
        label: "blah",
        source_range: [299; 300),
        delete: [299; 300),
        insert: "blah()$0",
        kind: Method,
        detail: "pub fn blah(&self)"
    }
]"###
        );
    }

    #[test]
    fn test_completion_works_in_consts() {
        assert_debug_snapshot_matches!(
        do_ref_completion(
            r"
            struct A { the_field: u32 }
            const X: u32 = {
                A { the_field: 92 }.<|>
            };
            ",
        ),
        @r###"[
    CompletionItem {
        label: "the_field",
        source_range: [106; 106),
        delete: [106; 106),
        insert: "the_field",
        kind: Field,
        detail: "u32"
    }
]"###
        );
    }
}