//! This module implements a reference search.
//! First, the element at the cursor position must be either an `ast::Name`
//! or `ast::NameRef`. If it's a `ast::NameRef`, at the classification step we
//! try to resolve the direct tree parent of this element, otherwise we
//! already have a definition and just need to get its HIR together with
//! some information that is needed for futher steps of searching.
//! After that, we collect files that might contain references and look
//! for text occurrences of the identifier. If there's an `ast::NameRef`
//! at the index that the match starts at and its tree parent is
//! resolved to the search element definition, we get a reference.

mod rename;

use hir::Semantics;
use ide_db::{
    defs::{classify_name, classify_name_ref, Definition},
    search::SearchScope,
    RootDatabase,
};
use syntax::{
    algo::find_node_at_offset,
    ast::{self, NameOwner},
    AstNode, SyntaxKind, SyntaxNode, TextRange, TokenAtOffset,
};

use crate::{display::TryToNav, FilePosition, FileRange, NavigationTarget, RangeInfo};

pub(crate) use self::rename::rename;

pub use ide_db::search::{Reference, ReferenceAccess, ReferenceKind};

#[derive(Debug, Clone)]
pub struct ReferenceSearchResult {
    declaration: Declaration,
    references: Vec<Reference>,
}

#[derive(Debug, Clone)]
pub struct Declaration {
    pub nav: NavigationTarget,
    pub kind: ReferenceKind,
    pub access: Option<ReferenceAccess>,
}

impl ReferenceSearchResult {
    pub fn declaration(&self) -> &Declaration {
        &self.declaration
    }

    pub fn decl_target(&self) -> &NavigationTarget {
        &self.declaration.nav
    }

    pub fn references(&self) -> &[Reference] {
        &self.references
    }

    /// Total number of references
    /// At least 1 since all valid references should
    /// Have a declaration
    pub fn len(&self) -> usize {
        self.references.len() + 1
    }
}

// allow turning ReferenceSearchResult into an iterator
// over References
impl IntoIterator for ReferenceSearchResult {
    type Item = Reference;
    type IntoIter = std::vec::IntoIter<Reference>;

    fn into_iter(mut self) -> Self::IntoIter {
        let mut v = Vec::with_capacity(self.len());
        v.push(Reference {
            file_range: FileRange {
                file_id: self.declaration.nav.file_id,
                range: self.declaration.nav.focus_or_full_range(),
            },
            kind: self.declaration.kind,
            access: self.declaration.access,
        });
        v.append(&mut self.references);
        v.into_iter()
    }
}

pub(crate) fn find_all_refs(
    sema: &Semantics<RootDatabase>,
    position: FilePosition,
    search_scope: Option<SearchScope>,
) -> Option<RangeInfo<ReferenceSearchResult>> {
    let _p = profile::span("find_all_refs");
    let syntax = sema.parse(position.file_id).syntax().clone();

    let (opt_name, search_kind) = if let Some(name) =
        get_struct_def_name_for_struct_literal_search(&sema, &syntax, position)
    {
        (Some(name), ReferenceKind::StructLiteral)
    } else {
        (
            sema.find_node_at_offset_with_descend::<ast::Name>(&syntax, position.offset),
            ReferenceKind::Other,
        )
    };

    let RangeInfo { range, info: def } = find_name(&sema, &syntax, position, opt_name)?;

    let references = def
        .find_usages(sema, search_scope)
        .into_iter()
        .filter(|r| search_kind == ReferenceKind::Other || search_kind == r.kind)
        .collect();

    let decl_range = def.try_to_nav(sema.db)?.focus_or_full_range();

    let declaration = Declaration {
        nav: def.try_to_nav(sema.db)?,
        kind: ReferenceKind::Other,
        access: decl_access(&def, &syntax, decl_range),
    };

    Some(RangeInfo::new(range, ReferenceSearchResult { declaration, references }))
}

fn find_name(
    sema: &Semantics<RootDatabase>,
    syntax: &SyntaxNode,
    position: FilePosition,
    opt_name: Option<ast::Name>,
) -> Option<RangeInfo<Definition>> {
    if let Some(name) = opt_name {
        let def = classify_name(sema, &name)?.definition(sema.db);
        let range = name.syntax().text_range();
        return Some(RangeInfo::new(range, def));
    }
    let name_ref =
        sema.find_node_at_offset_with_descend::<ast::NameRef>(&syntax, position.offset)?;
    let def = classify_name_ref(sema, &name_ref)?.definition(sema.db);
    let range = name_ref.syntax().text_range();
    Some(RangeInfo::new(range, def))
}

fn decl_access(def: &Definition, syntax: &SyntaxNode, range: TextRange) -> Option<ReferenceAccess> {
    match def {
        Definition::Local(_) | Definition::Field(_) => {}
        _ => return None,
    };

    let stmt = find_node_at_offset::<ast::LetStmt>(syntax, range.start())?;
    if stmt.initializer().is_some() {
        let pat = stmt.pat()?;
        if let ast::Pat::IdentPat(it) = pat {
            if it.mut_token().is_some() {
                return Some(ReferenceAccess::Write);
            }
        }
    }

    None
}

fn get_struct_def_name_for_struct_literal_search(
    sema: &Semantics<RootDatabase>,
    syntax: &SyntaxNode,
    position: FilePosition,
) -> Option<ast::Name> {
    if let TokenAtOffset::Between(ref left, ref right) = syntax.token_at_offset(position.offset) {
        if right.kind() != SyntaxKind::L_CURLY && right.kind() != SyntaxKind::L_PAREN {
            return None;
        }
        if let Some(name) =
            sema.find_node_at_offset_with_descend::<ast::Name>(&syntax, left.text_range().start())
        {
            return name.syntax().ancestors().find_map(ast::Struct::cast).and_then(|l| l.name());
        }
        if sema
            .find_node_at_offset_with_descend::<ast::GenericParamList>(
                &syntax,
                left.text_range().start(),
            )
            .is_some()
        {
            return left.ancestors().find_map(ast::Struct::cast).and_then(|l| l.name());
        }
    }
    None
}

#[cfg(test)]
mod tests {
    use crate::{
        mock_analysis::{analysis_and_position, MockAnalysis},
        Declaration, Reference, ReferenceSearchResult, SearchScope,
    };

    #[test]
    fn test_struct_literal_after_space() {
        let refs = get_all_refs(
            r#"
struct Foo <|>{
    a: i32,
}
impl Foo {
    fn f() -> i32 { 42 }
}
fn main() {
    let f: Foo;
    f = Foo {a: Foo::f()};
}
"#,
        );
        check_result(
            refs,
            "Foo STRUCT FileId(1) 0..26 7..10 Other",
            &["FileId(1) 101..104 StructLiteral"],
        );
    }

    #[test]
    fn test_struct_literal_before_space() {
        let refs = get_all_refs(
            r#"
struct Foo<|> {}
    fn main() {
    let f: Foo;
    f = Foo {};
}
"#,
        );
        check_result(
            refs,
            "Foo STRUCT FileId(1) 0..13 7..10 Other",
            &["FileId(1) 41..44 Other", "FileId(1) 54..57 StructLiteral"],
        );
    }

    #[test]
    fn test_struct_literal_with_generic_type() {
        let refs = get_all_refs(
            r#"
struct Foo<T> <|>{}
    fn main() {
    let f: Foo::<i32>;
    f = Foo {};
}
"#,
        );
        check_result(
            refs,
            "Foo STRUCT FileId(1) 0..16 7..10 Other",
            &["FileId(1) 64..67 StructLiteral"],
        );
    }

    #[test]
    fn test_struct_literal_for_tuple() {
        let refs = get_all_refs(
            r#"
struct Foo<|>(i32);

fn main() {
    let f: Foo;
    f = Foo(1);
}
"#,
        );
        check_result(
            refs,
            "Foo STRUCT FileId(1) 0..16 7..10 Other",
            &["FileId(1) 54..57 StructLiteral"],
        );
    }

    #[test]
    fn test_find_all_refs_for_local() {
        let refs = get_all_refs(
            r#"
fn main() {
    let mut i = 1;
    let j = 1;
    i = i<|> + j;

    {
        i = 0;
    }

    i = 5;
}"#,
        );
        check_result(
            refs,
            "i IDENT_PAT FileId(1) 24..25 Other Write",
            &[
                "FileId(1) 50..51 Other Write",
                "FileId(1) 54..55 Other Read",
                "FileId(1) 76..77 Other Write",
                "FileId(1) 94..95 Other Write",
            ],
        );
    }

    #[test]
    fn search_filters_by_range() {
        let refs = get_all_refs(
            r#"
fn foo() {
    let spam<|> = 92;
    spam + spam
}
fn bar() {
    let spam = 92;
    spam + spam
}
"#,
        );
        check_result(
            refs,
            "spam IDENT_PAT FileId(1) 19..23 Other",
            &["FileId(1) 34..38 Other Read", "FileId(1) 41..45 Other Read"],
        );
    }

    #[test]
    fn test_find_all_refs_for_param_inside() {
        let refs = get_all_refs(
            r#"
fn foo(i : u32) -> u32 {
    i<|>
}
"#,
        );
        check_result(refs, "i IDENT_PAT FileId(1) 7..8 Other", &["FileId(1) 29..30 Other Read"]);
    }

    #[test]
    fn test_find_all_refs_for_fn_param() {
        let refs = get_all_refs(
            r#"
fn foo(i<|> : u32) -> u32 {
    i
}
"#,
        );
        check_result(refs, "i IDENT_PAT FileId(1) 7..8 Other", &["FileId(1) 29..30 Other Read"]);
    }

    #[test]
    fn test_find_all_refs_field_name() {
        let refs = get_all_refs(
            r#"
//- /lib.rs
struct Foo {
    pub spam<|>: u32,
}

fn main(s: Foo) {
    let f = s.spam;
}
"#,
        );
        check_result(
            refs,
            "spam RECORD_FIELD FileId(1) 17..30 21..25 Other",
            &["FileId(1) 67..71 Other Read"],
        );
    }

    #[test]
    fn test_find_all_refs_impl_item_name() {
        let refs = get_all_refs(
            r#"
struct Foo;
impl Foo {
    fn f<|>(&self) {  }
}
"#,
        );
        check_result(refs, "f FN FileId(1) 27..43 30..31 Other", &[]);
    }

    #[test]
    fn test_find_all_refs_enum_var_name() {
        let refs = get_all_refs(
            r#"
enum Foo {
    A,
    B<|>,
    C,
}
"#,
        );
        check_result(refs, "B VARIANT FileId(1) 22..23 22..23 Other", &[]);
    }

    #[test]
    fn test_find_all_refs_two_modules() {
        let (analysis, pos) = analysis_and_position(
            r#"
//- /lib.rs
pub mod foo;
pub mod bar;

fn f() {
    let i = foo::Foo { n: 5 };
}

//- /foo.rs
use crate::bar;

pub struct Foo {
    pub n: u32,
}

fn f() {
    let i = bar::Bar { n: 5 };
}

//- /bar.rs
use crate::foo;

pub struct Bar {
    pub n: u32,
}

fn f() {
    let i = foo::Foo<|> { n: 5 };
}
"#,
        );
        let refs = analysis.find_all_refs(pos, None).unwrap().unwrap();
        check_result(
            refs,
            "Foo STRUCT FileId(2) 17..51 28..31 Other",
            &["FileId(1) 53..56 StructLiteral", "FileId(3) 79..82 StructLiteral"],
        );
    }

    // `mod foo;` is not in the results because `foo` is an `ast::Name`.
    // So, there are two references: the first one is a definition of the `foo` module,
    // which is the whole `foo.rs`, and the second one is in `use foo::Foo`.
    #[test]
    fn test_find_all_refs_decl_module() {
        let (analysis, pos) = analysis_and_position(
            r#"
//- /lib.rs
mod foo<|>;

use foo::Foo;

fn f() {
    let i = Foo { n: 5 };
}

//- /foo.rs
pub struct Foo {
    pub n: u32,
}
"#,
        );
        let refs = analysis.find_all_refs(pos, None).unwrap().unwrap();
        check_result(refs, "foo SOURCE_FILE FileId(2) 0..35 Other", &["FileId(1) 14..17 Other"]);
    }

    #[test]
    fn test_find_all_refs_super_mod_vis() {
        let (analysis, pos) = analysis_and_position(
            r#"
//- /lib.rs
mod foo;

//- /foo.rs
mod some;
use some::Foo;

fn f() {
    let i = Foo { n: 5 };
}

//- /foo/some.rs
pub(super) struct Foo<|> {
    pub n: u32,
}
"#,
        );
        let refs = analysis.find_all_refs(pos, None).unwrap().unwrap();
        check_result(
            refs,
            "Foo STRUCT FileId(3) 0..41 18..21 Other",
            &["FileId(2) 20..23 Other", "FileId(2) 47..50 StructLiteral"],
        );
    }

    #[test]
    fn test_find_all_refs_with_scope() {
        let code = r#"
            //- /lib.rs
            mod foo;
            mod bar;

            pub fn quux<|>() {}

            //- /foo.rs
            fn f() { super::quux(); }

            //- /bar.rs
            fn f() { super::quux(); }
        "#;

        let (mock, pos) = MockAnalysis::with_files_and_position(code);
        let bar = mock.id_of("/bar.rs");
        let analysis = mock.analysis();

        let refs = analysis.find_all_refs(pos, None).unwrap().unwrap();
        check_result(
            refs,
            "quux FN FileId(1) 19..35 26..30 Other",
            &["FileId(2) 16..20 StructLiteral", "FileId(3) 16..20 StructLiteral"],
        );

        let refs =
            analysis.find_all_refs(pos, Some(SearchScope::single_file(bar))).unwrap().unwrap();
        check_result(
            refs,
            "quux FN FileId(1) 19..35 26..30 Other",
            &["FileId(3) 16..20 StructLiteral"],
        );
    }

    #[test]
    fn test_find_all_refs_macro_def() {
        let refs = get_all_refs(
            r#"
#[macro_export]
macro_rules! m1<|> { () => (()) }

fn foo() {
    m1();
    m1();
}
"#,
        );
        check_result(
            refs,
            "m1 MACRO_CALL FileId(1) 0..46 29..31 Other",
            &["FileId(1) 63..65 StructLiteral", "FileId(1) 73..75 StructLiteral"],
        );
    }

    #[test]
    fn test_basic_highlight_read_write() {
        let refs = get_all_refs(
            r#"
fn foo() {
    let mut i<|> = 0;
    i = i + 1;
}
"#,
        );
        check_result(
            refs,
            "i IDENT_PAT FileId(1) 23..24 Other Write",
            &["FileId(1) 34..35 Other Write", "FileId(1) 38..39 Other Read"],
        );
    }

    #[test]
    fn test_basic_highlight_field_read_write() {
        let refs = get_all_refs(
            r#"
struct S {
    f: u32,
}

fn foo() {
    let mut s = S{f: 0};
    s.f<|> = 0;
}
"#,
        );
        check_result(
            refs,
            "f RECORD_FIELD FileId(1) 15..21 15..16 Other",
            &["FileId(1) 55..56 Other Read", "FileId(1) 68..69 Other Write"],
        );
    }

    #[test]
    fn test_basic_highlight_decl_no_write() {
        let refs = get_all_refs(
            r#"
fn foo() {
    let i<|>;
    i = 1;
}
"#,
        );
        check_result(refs, "i IDENT_PAT FileId(1) 19..20 Other", &["FileId(1) 26..27 Other Write"]);
    }

    #[test]
    fn test_find_struct_function_refs_outside_module() {
        let refs = get_all_refs(
            r#"
mod foo {
    pub struct Foo;

    impl Foo {
        pub fn new<|>() -> Foo {
            Foo
        }
    }
}

fn main() {
    let _f = foo::Foo::new();
}
"#,
        );
        check_result(
            refs,
            "new FN FileId(1) 54..101 61..64 Other",
            &["FileId(1) 146..149 StructLiteral"],
        );
    }

    #[test]
    fn test_find_all_refs_nested_module() {
        let code = r#"
            //- /lib.rs
            mod foo {
                mod bar;
            }

            fn f<|>() {}

            //- /foo/bar.rs
            use crate::f;

            fn g() {
                f();
            }
        "#;

        let (analysis, pos) = analysis_and_position(code);
        let refs = analysis.find_all_refs(pos, None).unwrap().unwrap();
        check_result(
            refs,
            "f FN FileId(1) 26..35 29..30 Other",
            &["FileId(2) 11..12 Other", "FileId(2) 28..29 StructLiteral"],
        );
    }

    fn get_all_refs(ra_fixture: &str) -> ReferenceSearchResult {
        let (analysis, position) = analysis_and_position(ra_fixture);
        analysis.find_all_refs(position, None).unwrap().unwrap()
    }

    fn check_result(res: ReferenceSearchResult, expected_decl: &str, expected_refs: &[&str]) {
        res.declaration().assert_match(expected_decl);
        assert_eq!(res.references.len(), expected_refs.len());
        res.references()
            .iter()
            .enumerate()
            .for_each(|(i, r)| ref_assert_match(r, expected_refs[i]));
    }

    impl Declaration {
        fn debug_render(&self) -> String {
            let mut s = format!("{} {:?}", self.nav.debug_render(), self.kind);
            if let Some(access) = self.access {
                s.push_str(&format!(" {:?}", access));
            }
            s
        }

        fn assert_match(&self, expected: &str) {
            let actual = self.debug_render();
            test_utils::assert_eq_text!(expected.trim(), actual.trim(),);
        }
    }

    fn ref_debug_render(r: &Reference) -> String {
        let mut s = format!("{:?} {:?} {:?}", r.file_range.file_id, r.file_range.range, r.kind);
        if let Some(access) = r.access {
            s.push_str(&format!(" {:?}", access));
        }
        s
    }

    fn ref_assert_match(r: &Reference, expected: &str) {
        let actual = ref_debug_render(r);
        test_utils::assert_eq_text!(expected.trim(), actual.trim(),);
    }
}