//! 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 classify;
mod name_definition;
mod rename;
mod search_scope;

use hir::{InFile, SourceBinder};
use once_cell::unsync::Lazy;
use ra_db::{SourceDatabase, SourceDatabaseExt};
use ra_prof::profile;
use ra_syntax::{
    algo::find_node_at_offset,
    ast::{self, NameOwner},
    match_ast, AstNode, SourceFile, SyntaxKind, SyntaxNode, TextRange, TextUnit, TokenAtOffset,
};

use crate::{
    db::RootDatabase, display::ToNav, FilePosition, FileRange, NavigationTarget, RangeInfo,
};

pub(crate) use self::{
    classify::{classify_name, classify_name_ref},
    name_definition::{NameDefinition, NameKind},
    rename::rename,
};

pub use self::search_scope::SearchScope;

#[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>,
}

#[derive(Debug, Clone)]
pub struct Reference {
    pub file_range: FileRange,
    pub kind: ReferenceKind,
    pub access: Option<ReferenceAccess>,
}

#[derive(Debug, Clone, PartialEq)]
pub enum ReferenceKind {
    StructLiteral,
    Other,
}

#[derive(Debug, Copy, Clone, PartialEq)]
pub enum ReferenceAccess {
    Read,
    Write,
}

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.range(),
            },
            kind: self.declaration.kind,
            access: self.declaration.access,
        });
        v.append(&mut self.references);
        v.into_iter()
    }
}

pub(crate) fn find_all_refs(
    db: &RootDatabase,
    mut position: FilePosition,
    search_scope: Option<SearchScope>,
) -> Option<RangeInfo<ReferenceSearchResult>> {
    let parse = db.parse(position.file_id);
    let syntax = parse.tree().syntax().clone();

    let token = syntax.token_at_offset(position.offset);
    let mut search_kind = ReferenceKind::Other;

    if let TokenAtOffset::Between(ref left, ref right) = token {
        if (right.kind() == SyntaxKind::L_CURLY || right.kind() == SyntaxKind::L_PAREN)
            && left.kind() != SyntaxKind::IDENT
        {
            position = FilePosition { offset: left.text_range().start(), ..position };
            search_kind = ReferenceKind::StructLiteral;
        }
    }

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

    let declaration = match def.kind {
        NameKind::Macro(mac) => mac.to_nav(db),
        NameKind::Field(field) => field.to_nav(db),
        NameKind::AssocItem(assoc) => assoc.to_nav(db),
        NameKind::Def(def) => NavigationTarget::from_def(db, def)?,
        NameKind::SelfType(imp) => imp.to_nav(db),
        NameKind::Local(local) => local.to_nav(db),
        NameKind::TypeParam(_) => return None,
    };

    let search_scope = {
        let base = def.search_scope(db);
        match search_scope {
            None => base,
            Some(scope) => base.intersection(&scope),
        }
    };

    let decl_range = declaration.range();

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

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

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

fn find_name(
    db: &RootDatabase,
    syntax: &SyntaxNode,
    position: FilePosition,
) -> Option<RangeInfo<(String, NameDefinition)>> {
    let mut sb = SourceBinder::new(db);
    if let Some(name) = find_node_at_offset::<ast::Name>(&syntax, position.offset) {
        let def = classify_name(&mut sb, InFile::new(position.file_id.into(), &name))?;
        let range = name.syntax().text_range();
        return Some(RangeInfo::new(range, (name.text().to_string(), def)));
    }
    let name_ref = find_node_at_offset::<ast::NameRef>(&syntax, position.offset)?;
    let def = classify_name_ref(&mut sb, InFile::new(position.file_id.into(), &name_ref))?;
    let range = name_ref.syntax().text_range();
    Some(RangeInfo::new(range, (name_ref.text().to_string(), def)))
}

fn process_definition(
    db: &RootDatabase,
    def: NameDefinition,
    name: String,
    scope: SearchScope,
) -> Vec<Reference> {
    let _p = profile("process_definition");

    let pat = name.as_str();
    let mut refs = vec![];

    for (file_id, search_range) in scope {
        let text = db.file_text(file_id);
        let parse = Lazy::new(|| SourceFile::parse(&text));

        for (idx, _) in text.match_indices(pat) {
            let offset = TextUnit::from_usize(idx);

            if let Some(name_ref) =
                find_node_at_offset::<ast::NameRef>(parse.tree().syntax(), offset)
            {
                let range = name_ref.syntax().text_range();
                if let Some(search_range) = search_range {
                    if !range.is_subrange(&search_range) {
                        continue;
                    }
                }
                // FIXME: reuse sb
                // See https://github.com/rust-lang/rust/pull/68198#issuecomment-574269098
                let mut sb = SourceBinder::new(db);
                if let Some(d) = classify_name_ref(&mut sb, InFile::new(file_id.into(), &name_ref))
                {
                    if d == def {
                        let kind = if name_ref
                            .syntax()
                            .ancestors()
                            .find_map(ast::RecordLit::cast)
                            .and_then(|l| l.path())
                            .and_then(|p| p.segment())
                            .and_then(|p| p.name_ref())
                            .map(|n| n == name_ref)
                            .unwrap_or(false)
                        {
                            ReferenceKind::StructLiteral
                        } else {
                            ReferenceKind::Other
                        };

                        refs.push(Reference {
                            file_range: FileRange { file_id, range },
                            kind,
                            access: reference_access(&d.kind, &name_ref),
                        });
                    }
                }
            }
        }
    }
    refs
}

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

    let stmt = find_node_at_offset::<ast::LetStmt>(syntax, range.start())?;
    if let Some(_) = stmt.initializer() {
        let pat = stmt.pat()?;
        if let ast::Pat::BindPat(it) = pat {
            if it.name()?.text().as_str() == name {
                return Some(ReferenceAccess::Write);
            }
        }
    }

    None
}

fn reference_access(kind: &NameKind, name_ref: &ast::NameRef) -> Option<ReferenceAccess> {
    // Only Locals and Fields have accesses for now.
    match kind {
        NameKind::Local(_) | NameKind::Field(_) => {}
        _ => return None,
    };

    let mode = name_ref.syntax().ancestors().find_map(|node| {
        match_ast! {
            match (node) {
                ast::BinExpr(expr) => {
                    if expr.op_kind()?.is_assignment() {
                        // If the variable or field ends on the LHS's end then it's a Write (covers fields and locals).
                        // FIXME: This is not terribly accurate.
                        if let Some(lhs) = expr.lhs() {
                            if lhs.syntax().text_range().end() == name_ref.syntax().text_range().end() {
                                return Some(ReferenceAccess::Write);
                            }
                        }
                    }
                    Some(ReferenceAccess::Read)
                },
                _ => {None}
            }
        }
    });

    // Default Locals and Fields to read
    mode.or(Some(ReferenceAccess::Read))
}

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

    #[test]
    fn test_struct_literal() {
        let code = r#"
    struct Foo <|>{
        a: i32,
    }
    impl Foo {
        fn f() -> i32 { 42 }
    }
    fn main() {
        let f: Foo;
        f = Foo {a: Foo::f()};
    }"#;

        let refs = get_all_refs(code);
        check_result(
            refs,
            "Foo STRUCT_DEF FileId(1) [5; 39) [12; 15) Other",
            &["FileId(1) [138; 141) StructLiteral"],
        );
    }

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

        {
            i = 0;
        }

        i = 5;
    }"#;

        let refs = get_all_refs(code);
        check_result(
            refs,
            "i BIND_PAT FileId(1) [33; 34) Other Write",
            &[
                "FileId(1) [67; 68) Other Write",
                "FileId(1) [71; 72) Other Read",
                "FileId(1) [101; 102) Other Write",
                "FileId(1) [127; 128) Other Write",
            ],
        );
    }

    #[test]
    fn test_find_all_refs_for_param_inside() {
        let code = r#"
    fn foo(i : u32) -> u32 {
        i<|>
    }"#;

        let refs = get_all_refs(code);
        check_result(
            refs,
            "i BIND_PAT FileId(1) [12; 13) Other",
            &["FileId(1) [38; 39) Other Read"],
        );
    }

    #[test]
    fn test_find_all_refs_for_fn_param() {
        let code = r#"
    fn foo(i<|> : u32) -> u32 {
        i
    }"#;

        let refs = get_all_refs(code);
        check_result(
            refs,
            "i BIND_PAT FileId(1) [12; 13) Other",
            &["FileId(1) [38; 39) Other Read"],
        );
    }

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

            fn main(s: Foo) {
                let f = s.spam;
            }
        "#;

        let refs = get_all_refs(code);
        check_result(
            refs,
            "spam RECORD_FIELD_DEF FileId(1) [66; 79) [70; 74) Other",
            &["FileId(1) [152; 156) Other Read"],
        );
    }

    #[test]
    fn test_find_all_refs_impl_item_name() {
        let code = r#"
            //- /lib.rs
            struct Foo;
            impl Foo {
                fn f<|>(&self) {  }
            }
        "#;

        let refs = get_all_refs(code);
        check_result(refs, "f FN_DEF FileId(1) [88; 104) [91; 92) Other", &[]);
    }

    #[test]
    fn test_find_all_refs_enum_var_name() {
        let code = r#"
            //- /lib.rs
            enum Foo {
                A,
                B<|>,
                C,
            }
        "#;

        let refs = get_all_refs(code);
        check_result(refs, "B ENUM_VARIANT FileId(1) [83; 84) [83; 84) Other", &[]);
    }

    #[test]
    fn test_find_all_refs_two_modules() {
        let code = 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 (analysis, pos) = analysis_and_position(code);
        let refs = analysis.find_all_refs(pos, None).unwrap().unwrap();
        check_result(
            refs,
            "Foo STRUCT_DEF FileId(2) [16; 50) [27; 30) Other",
            &["FileId(1) [52; 55) StructLiteral", "FileId(3) [77; 80) 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 code = r#"
            //- /lib.rs
            mod foo<|>;

            use foo::Foo;

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

            //- /foo.rs
            pub struct Foo {
                pub n: u32,
            }
        "#;

        let (analysis, pos) = analysis_and_position(code);
        let refs = analysis.find_all_refs(pos, None).unwrap().unwrap();
        check_result(
            refs,
            "foo SOURCE_FILE FileId(2) [0; 35) Other",
            &["FileId(1) [13; 16) Other"],
        );
    }

    #[test]
    fn test_find_all_refs_super_mod_vis() {
        let code = 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 (analysis, pos) = analysis_and_position(code);
        let refs = analysis.find_all_refs(pos, None).unwrap().unwrap();
        check_result(
            refs,
            "Foo STRUCT_DEF FileId(3) [0; 41) [18; 21) Other",
            &["FileId(2) [20; 23) Other", "FileId(2) [46; 49) 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_DEF FileId(1) [18; 34) [25; 29) Other",
            &["FileId(2) [16; 20) Other", "FileId(3) [16; 20) Other"],
        );

        let refs =
            analysis.find_all_refs(pos, Some(SearchScope::single_file(bar))).unwrap().unwrap();
        check_result(
            refs,
            "quux FN_DEF FileId(1) [18; 34) [25; 29) Other",
            &["FileId(3) [16; 20) Other"],
        );
    }

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

        fn foo() {
            m1();
            m1();
        }"#;

        let refs = get_all_refs(code);
        check_result(
            refs,
            "m1 MACRO_CALL FileId(1) [9; 63) [46; 48) Other",
            &["FileId(1) [96; 98) Other", "FileId(1) [114; 116) Other"],
        );
    }

    #[test]
    fn test_basic_highlight_read_write() {
        let code = r#"
        fn foo() {
            let i<|> = 0;
            i = i + 1;
        }"#;

        let refs = get_all_refs(code);
        check_result(
            refs,
            "i BIND_PAT FileId(1) [36; 37) Other Write",
            &["FileId(1) [55; 56) Other Write", "FileId(1) [59; 60) Other Read"],
        );
    }

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

        fn foo() {
            let mut s = S{f: 0};
            s.f<|> = 0;
        }"#;

        let refs = get_all_refs(code);
        check_result(
            refs,
            "f RECORD_FIELD_DEF FileId(1) [32; 38) [32; 33) Other",
            &["FileId(1) [96; 97) Other Read", "FileId(1) [117; 118) Other Write"],
        );
    }

    #[test]
    fn test_basic_highlight_decl_no_write() {
        let code = r#"
        fn foo() {
            let i<|>;
            i = 1;
        }"#;

        let refs = get_all_refs(code);
        check_result(
            refs,
            "i BIND_PAT FileId(1) [36; 37) Other",
            &["FileId(1) [51; 52) Other Write"],
        );
    }

    fn get_all_refs(text: &str) -> ReferenceSearchResult {
        let (analysis, position) = single_file_with_position(text);
        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)| r.assert_match(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(),);
        }
    }

    impl Reference {
        fn debug_render(&self) -> String {
            let mut s = format!(
                "{:?} {:?} {:?}",
                self.file_range.file_id, self.file_range.range, 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(),);
        }
    }
}