//! FIXME: write short doc here

use either::Either;
use hir::{AssocItem, FieldSource, HasSource, InFile, ModuleSource};
use ra_db::{FileId, SourceDatabase};
use ra_syntax::{
    ast::{self, DocCommentsOwner, NameOwner},
    match_ast, AstNode, SmolStr,
    SyntaxKind::{self, BIND_PAT, TYPE_PARAM},
    TextRange,
};

use crate::{db::RootDatabase, expand::original_range, FileSymbol};

use super::short_label::ShortLabel;

/// `NavigationTarget` represents and element in the editor's UI which you can
/// click on to navigate to a particular piece of code.
///
/// Typically, a `NavigationTarget` corresponds to some element in the source
/// code, like a function or a struct, but this is not strictly required.
#[derive(Debug, Clone)]
pub struct NavigationTarget {
    file_id: FileId,
    name: SmolStr,
    kind: SyntaxKind,
    full_range: TextRange,
    focus_range: Option<TextRange>,
    container_name: Option<SmolStr>,
    description: Option<String>,
    docs: Option<String>,
}

pub(crate) trait ToNav {
    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget;
}

impl NavigationTarget {
    /// When `focus_range` is specified, returns it. otherwise
    /// returns `full_range`
    pub fn range(&self) -> TextRange {
        self.focus_range.unwrap_or(self.full_range)
    }

    pub fn name(&self) -> &SmolStr {
        &self.name
    }

    pub fn container_name(&self) -> Option<&SmolStr> {
        self.container_name.as_ref()
    }

    pub fn kind(&self) -> SyntaxKind {
        self.kind
    }

    pub fn file_id(&self) -> FileId {
        self.file_id
    }

    pub fn full_range(&self) -> TextRange {
        self.full_range
    }

    pub fn docs(&self) -> Option<&str> {
        self.docs.as_ref().map(String::as_str)
    }

    pub fn description(&self) -> Option<&str> {
        self.description.as_ref().map(String::as_str)
    }

    /// A "most interesting" range withing the `full_range`.
    ///
    /// Typically, `full_range` is the whole syntax node,
    /// including doc comments, and `focus_range` is the range of the identifier.
    pub fn focus_range(&self) -> Option<TextRange> {
        self.focus_range
    }

    pub(crate) fn from_module_to_decl(db: &RootDatabase, module: hir::Module) -> NavigationTarget {
        let name = module.name(db).map(|it| it.to_string().into()).unwrap_or_default();
        if let Some(src) = module.declaration_source(db) {
            let frange = original_range(db, src.as_ref().map(|it| it.syntax()));
            return NavigationTarget::from_syntax(
                frange.file_id,
                name,
                None,
                frange.range,
                src.value.syntax().kind(),
                src.value.doc_comment_text(),
                src.value.short_label(),
            );
        }
        module.to_nav(db)
    }

    pub(crate) fn from_def(
        db: &RootDatabase,
        module_def: hir::ModuleDef,
    ) -> Option<NavigationTarget> {
        let nav = match module_def {
            hir::ModuleDef::Module(module) => module.to_nav(db),
            hir::ModuleDef::Function(it) => it.to_nav(db),
            hir::ModuleDef::Adt(it) => it.to_nav(db),
            hir::ModuleDef::Const(it) => it.to_nav(db),
            hir::ModuleDef::Static(it) => it.to_nav(db),
            hir::ModuleDef::EnumVariant(it) => it.to_nav(db),
            hir::ModuleDef::Trait(it) => it.to_nav(db),
            hir::ModuleDef::TypeAlias(it) => it.to_nav(db),
            hir::ModuleDef::BuiltinType(..) => {
                return None;
            }
        };
        Some(nav)
    }

    #[cfg(test)]
    pub(crate) fn assert_match(&self, expected: &str) {
        let actual = self.debug_render();
        test_utils::assert_eq_text!(expected.trim(), actual.trim(),);
    }

    #[cfg(test)]
    pub(crate) fn debug_render(&self) -> String {
        let mut buf = format!(
            "{} {:?} {:?} {:?}",
            self.name(),
            self.kind(),
            self.file_id(),
            self.full_range()
        );
        if let Some(focus_range) = self.focus_range() {
            buf.push_str(&format!(" {:?}", focus_range))
        }
        if let Some(container_name) = self.container_name() {
            buf.push_str(&format!(" {}", container_name))
        }
        buf
    }

    /// Allows `NavigationTarget` to be created from a `NameOwner`
    pub(crate) fn from_named(
        db: &RootDatabase,
        node: InFile<&dyn ast::NameOwner>,
        docs: Option<String>,
        description: Option<String>,
    ) -> NavigationTarget {
        //FIXME: use `_` instead of empty string
        let name = node.value.name().map(|it| it.text().clone()).unwrap_or_default();
        let focus_range =
            node.value.name().map(|it| original_range(db, node.with_value(it.syntax())).range);
        let frange = original_range(db, node.map(|it| it.syntax()));

        NavigationTarget::from_syntax(
            frange.file_id,
            name,
            focus_range,
            frange.range,
            node.value.syntax().kind(),
            docs,
            description,
        )
    }

    fn from_syntax(
        file_id: FileId,
        name: SmolStr,
        focus_range: Option<TextRange>,
        full_range: TextRange,
        kind: SyntaxKind,
        docs: Option<String>,
        description: Option<String>,
    ) -> NavigationTarget {
        NavigationTarget {
            file_id,
            name,
            kind,
            full_range,
            focus_range,
            container_name: None,
            description,
            docs,
        }
    }
}

impl ToNav for FileSymbol {
    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
        NavigationTarget {
            file_id: self.file_id,
            name: self.name.clone(),
            kind: self.ptr.kind(),
            full_range: self.ptr.range(),
            focus_range: self.name_range,
            container_name: self.container_name.clone(),
            description: description_from_symbol(db, self),
            docs: docs_from_symbol(db, self),
        }
    }
}

pub(crate) trait ToNavFromAst {}
impl ToNavFromAst for hir::Function {}
impl ToNavFromAst for hir::Const {}
impl ToNavFromAst for hir::Static {}
impl ToNavFromAst for hir::Struct {}
impl ToNavFromAst for hir::Enum {}
impl ToNavFromAst for hir::EnumVariant {}
impl ToNavFromAst for hir::Union {}
impl ToNavFromAst for hir::TypeAlias {}
impl ToNavFromAst for hir::Trait {}

impl<D> ToNav for D
where
    D: HasSource + ToNavFromAst + Copy,
    D::Ast: ast::DocCommentsOwner + ast::NameOwner + ShortLabel,
{
    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
        let src = self.source(db);
        NavigationTarget::from_named(
            db,
            src.as_ref().map(|it| it as &dyn ast::NameOwner),
            src.value.doc_comment_text(),
            src.value.short_label(),
        )
    }
}

impl ToNav for hir::Module {
    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
        let src = self.definition_source(db);
        let name = self.name(db).map(|it| it.to_string().into()).unwrap_or_default();
        let syntax = match &src.value {
            ModuleSource::SourceFile(node) => node.syntax(),
            ModuleSource::Module(node) => node.syntax(),
        };
        let frange = original_range(db, src.with_value(syntax));
        NavigationTarget::from_syntax(
            frange.file_id,
            name,
            None,
            frange.range,
            syntax.kind(),
            None,
            None,
        )
    }
}

impl ToNav for hir::ImplBlock {
    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
        let src = self.source(db);
        let frange = original_range(db, src.as_ref().map(|it| it.syntax()));

        NavigationTarget::from_syntax(
            frange.file_id,
            "impl".into(),
            None,
            frange.range,
            src.value.syntax().kind(),
            None,
            None,
        )
    }
}

impl ToNav for hir::StructField {
    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
        let src = self.source(db);

        match &src.value {
            FieldSource::Named(it) => NavigationTarget::from_named(
                db,
                src.with_value(it),
                it.doc_comment_text(),
                it.short_label(),
            ),
            FieldSource::Pos(it) => {
                let frange = original_range(db, src.with_value(it.syntax()));
                NavigationTarget::from_syntax(
                    frange.file_id,
                    "".into(),
                    None,
                    frange.range,
                    it.syntax().kind(),
                    None,
                    None,
                )
            }
        }
    }
}

impl ToNav for hir::MacroDef {
    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
        let src = self.source(db);
        log::debug!("nav target {:#?}", src.value.syntax());
        NavigationTarget::from_named(
            db,
            src.as_ref().map(|it| it as &dyn ast::NameOwner),
            src.value.doc_comment_text(),
            None,
        )
    }
}

impl ToNav for hir::Adt {
    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
        match self {
            hir::Adt::Struct(it) => it.to_nav(db),
            hir::Adt::Union(it) => it.to_nav(db),
            hir::Adt::Enum(it) => it.to_nav(db),
        }
    }
}

impl ToNav for hir::AssocItem {
    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
        match self {
            AssocItem::Function(it) => it.to_nav(db),
            AssocItem::Const(it) => it.to_nav(db),
            AssocItem::TypeAlias(it) => it.to_nav(db),
        }
    }
}

impl ToNav for hir::Local {
    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
        let src = self.source(db);
        let node = match &src.value {
            Either::Left(bind_pat) => {
                bind_pat.name().map_or_else(|| bind_pat.syntax().clone(), |it| it.syntax().clone())
            }
            Either::Right(it) => it.syntax().clone(),
        };
        let full_range = original_range(db, src.with_value(&node));
        let name = match self.name(db) {
            Some(it) => it.to_string().into(),
            None => "".into(),
        };
        NavigationTarget {
            file_id: full_range.file_id,
            name,
            kind: BIND_PAT,
            full_range: full_range.range,
            focus_range: None,
            container_name: None,
            description: None,
            docs: None,
        }
    }
}

impl ToNav for hir::TypeParam {
    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
        let src = self.source(db);
        let range = match src.value {
            Either::Left(it) => it.syntax().text_range(),
            Either::Right(it) => it.syntax().text_range(),
        };
        NavigationTarget {
            file_id: src.file_id.original_file(db),
            name: self.name(db).to_string().into(),
            kind: TYPE_PARAM,
            full_range: range,
            focus_range: None,
            container_name: None,
            description: None,
            docs: None,
        }
    }
}

pub(crate) fn docs_from_symbol(db: &RootDatabase, symbol: &FileSymbol) -> Option<String> {
    let parse = db.parse(symbol.file_id);
    let node = symbol.ptr.to_node(parse.tree().syntax());

    match_ast! {
        match node {
            ast::FnDef(it) => { it.doc_comment_text() },
            ast::StructDef(it) => { it.doc_comment_text() },
            ast::EnumDef(it) => { it.doc_comment_text() },
            ast::TraitDef(it) => { it.doc_comment_text() },
            ast::Module(it) => { it.doc_comment_text() },
            ast::TypeAliasDef(it) => { it.doc_comment_text() },
            ast::ConstDef(it) => { it.doc_comment_text() },
            ast::StaticDef(it) => { it.doc_comment_text() },
            ast::RecordFieldDef(it) => { it.doc_comment_text() },
            ast::EnumVariant(it) => { it.doc_comment_text() },
            ast::MacroCall(it) => { it.doc_comment_text() },
            _ => None,
        }
    }
}

/// Get a description of a symbol.
///
/// e.g. `struct Name`, `enum Name`, `fn Name`
pub(crate) fn description_from_symbol(db: &RootDatabase, symbol: &FileSymbol) -> Option<String> {
    let parse = db.parse(symbol.file_id);
    let node = symbol.ptr.to_node(parse.tree().syntax());

    match_ast! {
        match node {
            ast::FnDef(it) => { it.short_label() },
            ast::StructDef(it) => { it.short_label() },
            ast::EnumDef(it) => { it.short_label() },
            ast::TraitDef(it) => { it.short_label() },
            ast::Module(it) => { it.short_label() },
            ast::TypeAliasDef(it) => { it.short_label() },
            ast::ConstDef(it) => { it.short_label() },
            ast::StaticDef(it) => { it.short_label() },
            ast::RecordFieldDef(it) => { it.short_label() },
            ast::EnumVariant(it) => { it.short_label() },
            _ => None,
        }
    }
}
