//! Complete fields in record literals and patterns.
use ide_db::SymbolKind;
use syntax::ast::{self, Expr};

use crate::{
    context::{DotAccess, DotAccessKind, ExprCtx, PathCompletionCtx, PatternContext, Qualified},
    CompletionContext, CompletionItem, CompletionItemKind, CompletionRelevance,
    CompletionRelevancePostfixMatch, Completions,
};

pub(crate) fn complete_record_pattern_fields(
    acc: &mut Completions,
    ctx: &CompletionContext,
    pattern_ctx: &PatternContext,
) {
    if let PatternContext { record_pat: Some(record_pat), .. } = pattern_ctx {
        complete_fields(acc, ctx, ctx.sema.record_pattern_missing_fields(record_pat));
    }
}

pub(crate) fn complete_record_expr_fields(
    acc: &mut Completions,
    ctx: &CompletionContext,
    record_expr: &ast::RecordExpr,
    &dot_prefix: &bool,
) {
    let ty = ctx.sema.type_of_expr(&Expr::RecordExpr(record_expr.clone()));

    let missing_fields = match ty.as_ref().and_then(|t| t.original.as_adt()) {
        Some(hir::Adt::Union(un)) => {
            // ctx.sema.record_literal_missing_fields will always return
            // an empty Vec on a union literal. This is normally
            // reasonable, but here we'd like to present the full list
            // of fields if the literal is empty.
            let were_fields_specified =
                record_expr.record_expr_field_list().and_then(|fl| fl.fields().next()).is_some();

            match were_fields_specified {
                false => un.fields(ctx.db).into_iter().map(|f| (f, f.ty(ctx.db))).collect(),
                true => return,
            }
        }
        _ => {
            let missing_fields = ctx.sema.record_literal_missing_fields(record_expr);
            add_default_update(acc, ctx, ty, &missing_fields);
            if dot_prefix {
                let mut item =
                    CompletionItem::new(CompletionItemKind::Snippet, ctx.source_range(), "..");
                item.insert_text(".");
                item.add_to(acc);
                return;
            }
            missing_fields
        }
    };
    complete_fields(acc, ctx, missing_fields);
}

// FIXME: This should probably be part of complete_path_expr
pub(crate) fn complete_record_expr_func_update(
    acc: &mut Completions,
    ctx: &CompletionContext,
    path_ctx: &PathCompletionCtx,
    expr_ctx: &ExprCtx,
) {
    if !matches!(path_ctx.qualified, Qualified::No) {
        return;
    }
    if let ExprCtx { is_func_update: Some(record_expr), .. } = expr_ctx {
        let ty = ctx.sema.type_of_expr(&Expr::RecordExpr(record_expr.clone()));

        match ty.as_ref().and_then(|t| t.original.as_adt()) {
            Some(hir::Adt::Union(_)) => (),
            _ => {
                let missing_fields = ctx.sema.record_literal_missing_fields(record_expr);
                add_default_update(acc, ctx, ty, &missing_fields);
            }
        };
    }
}

fn add_default_update(
    acc: &mut Completions,
    ctx: &CompletionContext,
    ty: Option<hir::TypeInfo>,
    missing_fields: &[(hir::Field, hir::Type)],
) {
    let default_trait = ctx.famous_defs().core_default_Default();
    let impl_default_trait = default_trait
        .zip(ty.as_ref())
        .map_or(false, |(default_trait, ty)| ty.original.impls_trait(ctx.db, default_trait, &[]));
    if impl_default_trait && !missing_fields.is_empty() {
        // FIXME: This should make use of scope_def like completions so we get all the other goodies
        let completion_text = "..Default::default()";
        let mut item = CompletionItem::new(SymbolKind::Field, ctx.source_range(), completion_text);
        let completion_text =
            completion_text.strip_prefix(ctx.token.text()).unwrap_or(completion_text);
        item.insert_text(completion_text).set_relevance(CompletionRelevance {
            postfix_match: Some(CompletionRelevancePostfixMatch::Exact),
            ..Default::default()
        });
        item.add_to(acc);
    }
}

fn complete_fields(
    acc: &mut Completions,
    ctx: &CompletionContext,
    missing_fields: Vec<(hir::Field, hir::Type)>,
) {
    for (field, ty) in missing_fields {
        acc.add_field(
            ctx,
            &DotAccess {
                receiver: None,
                receiver_ty: None,
                kind: DotAccessKind::Field { receiver_is_ambiguous_float_literal: false },
            },
            None,
            field,
            &ty,
        );
    }
}

#[cfg(test)]
mod tests {
    use crate::tests::check_edit;

    #[test]
    fn literal_struct_completion_edit() {
        check_edit(
            "FooDesc {…}",
            r#"
struct FooDesc { pub bar: bool }

fn create_foo(foo_desc: &FooDesc) -> () { () }

fn baz() {
    let foo = create_foo(&$0);
}
            "#,
            r#"
struct FooDesc { pub bar: bool }

fn create_foo(foo_desc: &FooDesc) -> () { () }

fn baz() {
    let foo = create_foo(&FooDesc { bar: ${1:()} }$0);
}
            "#,
        )
    }

    #[test]
    fn literal_struct_impl_self_completion() {
        check_edit(
            "Self {…}",
            r#"
struct Foo {
    bar: u64,
}

impl Foo {
    fn new() -> Foo {
        Self$0
    }
}
            "#,
            r#"
struct Foo {
    bar: u64,
}

impl Foo {
    fn new() -> Foo {
        Self { bar: ${1:()} }$0
    }
}
            "#,
        );

        check_edit(
            "Self(…)",
            r#"
mod submod {
    pub struct Foo(pub u64);
}

impl submod::Foo {
    fn new() -> submod::Foo {
        Self$0
    }
}
            "#,
            r#"
mod submod {
    pub struct Foo(pub u64);
}

impl submod::Foo {
    fn new() -> submod::Foo {
        Self(${1:()})$0
    }
}
            "#,
        )
    }

    #[test]
    fn literal_struct_completion_from_sub_modules() {
        check_edit(
            "submod::Struct {…}",
            r#"
mod submod {
    pub struct Struct {
        pub a: u64,
    }
}

fn f() -> submod::Struct {
    Stru$0
}
            "#,
            r#"
mod submod {
    pub struct Struct {
        pub a: u64,
    }
}

fn f() -> submod::Struct {
    submod::Struct { a: ${1:()} }$0
}
            "#,
        )
    }

    #[test]
    fn literal_struct_complexion_module() {
        check_edit(
            "FooDesc {…}",
            r#"
mod _69latrick {
    pub struct FooDesc { pub six: bool, pub neuf: Vec<String>, pub bar: bool }
    pub fn create_foo(foo_desc: &FooDesc) -> () { () }
}

fn baz() {
    use _69latrick::*;

    let foo = create_foo(&$0);
}
            "#,
            r#"
mod _69latrick {
    pub struct FooDesc { pub six: bool, pub neuf: Vec<String>, pub bar: bool }
    pub fn create_foo(foo_desc: &FooDesc) -> () { () }
}

fn baz() {
    use _69latrick::*;

    let foo = create_foo(&FooDesc { six: ${1:()}, neuf: ${2:()}, bar: ${3:()} }$0);
}
            "#,
        );
    }

    #[test]
    fn default_completion_edit() {
        check_edit(
            "..Default::default()",
            r#"
//- minicore: default
struct Struct { foo: u32, bar: usize }

impl Default for Struct {
    fn default() -> Self {}
}

fn foo() {
    let other = Struct {
        foo: 5,
        .$0
    };
}
"#,
            r#"
struct Struct { foo: u32, bar: usize }

impl Default for Struct {
    fn default() -> Self {}
}

fn foo() {
    let other = Struct {
        foo: 5,
        ..Default::default()
    };
}
"#,
        );
        check_edit(
            "..Default::default()",
            r#"
//- minicore: default
struct Struct { foo: u32, bar: usize }

impl Default for Struct {
    fn default() -> Self {}
}

fn foo() {
    let other = Struct {
        foo: 5,
        $0
    };
}
"#,
            r#"
struct Struct { foo: u32, bar: usize }

impl Default for Struct {
    fn default() -> Self {}
}

fn foo() {
    let other = Struct {
        foo: 5,
        ..Default::default()
    };
}
"#,
        );
        check_edit(
            "..Default::default()",
            r#"
//- minicore: default
struct Struct { foo: u32, bar: usize }

impl Default for Struct {
    fn default() -> Self {}
}

fn foo() {
    let other = Struct {
        foo: 5,
        ..$0
    };
}
"#,
            r#"
struct Struct { foo: u32, bar: usize }

impl Default for Struct {
    fn default() -> Self {}
}

fn foo() {
    let other = Struct {
        foo: 5,
        ..Default::default()
    };
}
"#,
        );
    }
}