use smol_str::SmolStr;

use super::ast::{
    self, FunctionDeclaration, FunctionDeclarationGreen, FunctionWithBody, FunctionWithBodyPtr,
    ImplItem, Item, ItemConstant, ItemEnum, ItemExternFunction, ItemExternFunctionPtr,
    ItemExternType, ItemImpl, ItemImplAlias, ItemInlineMacro, ItemModule, ItemStruct, ItemTrait,
    ItemTypeAlias, ItemUse, Member, Modifier, OptionArgListParenthesized, TerminalIdentifierGreen,
    TokenIdentifierGreen, TraitItem, TraitItemFunction, TraitItemFunctionPtr, Variant,
};
use super::db::SyntaxGroup;
use super::{Terminal, TypedSyntaxNode};
use crate::node::ast::{Attribute, AttributeList};
use crate::node::green::GreenNodeDetails;

#[cfg(test)]
#[path = "helpers_test.rs"]
mod test;

pub trait GetIdentifier {
    fn identifier(&self, db: &dyn SyntaxGroup) -> SmolStr;
}
impl ast::UsePathLeafPtr {
    pub fn name_green(&self, _syntax_db: &dyn SyntaxGroup) -> Self {
        *self
    }
}
impl GetIdentifier for ast::UsePathLeafPtr {
    fn identifier(&self, db: &dyn SyntaxGroup) -> SmolStr {
        let alias_clause_green = self.alias_clause_green(db).0;
        let children = match db.lookup_intern_green(alias_clause_green).details {
            GreenNodeDetails::Node { children, width: _ } => children,
            _ => panic!("Unexpected token"),
        };
        if !children.is_empty() {
            return ast::TerminalIdentifierGreen(children[ast::AliasClause::INDEX_ALIAS])
                .identifier(db);
        }
        let ident_green = self.ident_green(db);
        ident_green.identifier(db)
    }
}
impl GetIdentifier for ast::PathSegmentGreen {
    /// Retrieves the text of the last identifier in the path.
    fn identifier(&self, db: &dyn SyntaxGroup) -> SmolStr {
        let children = match db.lookup_intern_green(self.0).details {
            GreenNodeDetails::Node { children, width: _ } => children,
            _ => panic!("Unexpected token"),
        };
        let identifier = ast::TerminalIdentifierGreen(children[0]);
        identifier.identifier(db)
    }
}
impl GetIdentifier for ast::ExprPathGreen {
    /// Retrieves the text of the last identifier in the path.
    fn identifier(&self, db: &dyn SyntaxGroup) -> SmolStr {
        let children = match db.lookup_intern_green(self.0).details {
            GreenNodeDetails::Node { children, width: _ } => children,
            _ => panic!("Unexpected token"),
        };
        assert_eq!(children.len() & 1, 1, "Expected an odd number of elements in the path.");
        let segment_green = ast::PathSegmentGreen(*children.last().unwrap());
        segment_green.identifier(db)
    }
}
impl GetIdentifier for ast::TerminalIdentifierGreen {
    fn identifier(&self, db: &dyn SyntaxGroup) -> SmolStr {
        match db.lookup_intern_green(self.0).details {
            GreenNodeDetails::Token(_) => "Unexpected token".into(),
            GreenNodeDetails::Node { children, width: _ } => {
                TokenIdentifierGreen(children[1]).text(db)
            }
        }
    }
}
impl GetIdentifier for ast::ExprPath {
    /// Retrieves the identifier of the last segment of the path.
    fn identifier(&self, db: &dyn SyntaxGroup) -> SmolStr {
        self.elements(db).last().cloned().unwrap().identifier(db)
    }
}

/// Helper trait for ast::PathSegment.
pub trait PathSegmentEx {
    fn identifier_ast(&self, db: &dyn SyntaxGroup) -> ast::TerminalIdentifier;
    fn generic_args(&self, db: &dyn SyntaxGroup) -> Option<Vec<ast::GenericArg>>;
}
impl PathSegmentEx for ast::PathSegment {
    /// Retrieves the identifier ast of a path segment.
    fn identifier_ast(&self, db: &dyn SyntaxGroup) -> ast::TerminalIdentifier {
        match self {
            ast::PathSegment::Simple(segment) => segment.ident(db),
            ast::PathSegment::WithGenericArgs(segment) => segment.ident(db),
        }
    }
    fn generic_args(&self, db: &dyn SyntaxGroup) -> Option<Vec<ast::GenericArg>> {
        match self {
            ast::PathSegment::Simple(_) => None,
            ast::PathSegment::WithGenericArgs(segment) => {
                Some(segment.generic_args(db).generic_args(db).elements(db))
            }
        }
    }
}
impl GetIdentifier for ast::PathSegment {
    /// Retrieves the text of the segment (without the generic args).
    fn identifier(&self, db: &dyn SyntaxGroup) -> SmolStr {
        self.identifier_ast(db).text(db)
    }
}
impl GetIdentifier for ast::Modifier {
    fn identifier(&self, db: &dyn SyntaxGroup) -> SmolStr {
        match self {
            Modifier::Ref(r) => r.text(db),
            Modifier::Mut(m) => m.text(db),
        }
    }
}

/// Trait for ast object with a name terminal.
pub trait NameGreen {
    /// Returns the TerminalIdentifierGreen of the `name` node.
    fn name_green(self, db: &dyn SyntaxGroup) -> TerminalIdentifierGreen;
}

impl NameGreen for FunctionDeclarationGreen {
    fn name_green(self, db: &dyn SyntaxGroup) -> TerminalIdentifierGreen {
        TerminalIdentifierGreen(
            db.lookup_intern_green(self.0).children()[FunctionDeclaration::INDEX_NAME],
        )
    }
}

impl NameGreen for FunctionWithBodyPtr {
    fn name_green(self, db: &dyn SyntaxGroup) -> TerminalIdentifierGreen {
        self.declaration_green(db).name_green(db)
    }
}

impl NameGreen for ItemExternFunctionPtr {
    fn name_green(self, db: &dyn SyntaxGroup) -> TerminalIdentifierGreen {
        self.declaration_green(db).name_green(db)
    }
}

impl NameGreen for TraitItemFunctionPtr {
    fn name_green(self, db: &dyn SyntaxGroup) -> TerminalIdentifierGreen {
        self.declaration_green(db).name_green(db)
    }
}

pub trait GenericParamEx {
    /// Returns the name of a generic param if one exists.
    fn name(&self, db: &dyn SyntaxGroup) -> Option<ast::TerminalIdentifier>;
}
impl GenericParamEx for ast::GenericParam {
    fn name(&self, db: &dyn SyntaxGroup) -> Option<ast::TerminalIdentifier> {
        match self {
            ast::GenericParam::Type(t) => Some(t.name(db)),
            ast::GenericParam::Const(c) => Some(c.name(db)),
            ast::GenericParam::ImplNamed(i) => Some(i.name(db)),
            ast::GenericParam::ImplAnonymous(_) => None,
        }
    }
}

/// Checks if the given attribute has a single argument with the given name.
pub fn is_single_arg_attr(db: &dyn SyntaxGroup, attr: &Attribute, arg_name: &str) -> bool {
    match attr.arguments(db) {
        OptionArgListParenthesized::ArgListParenthesized(args) => {
            matches!(&args.args(db).elements(db)[..],
                    [arg] if arg.as_syntax_node().get_text_without_trivia(db) == arg_name)
        }
        OptionArgListParenthesized::Empty(_) => false,
    }
}

/// Trait for querying attributes of AST items.
pub trait QueryAttrs {
    /// Generic call `self.attributes(db).elements(db)`.
    ///
    /// Implementation detail, should not be used by this trait users.
    #[doc(hidden)]
    fn attributes_elements(&self, db: &dyn SyntaxGroup) -> Vec<Attribute>;

    /// Collect all attributes named exactly `attr` attached to this node.
    fn query_attr(&self, db: &dyn SyntaxGroup, attr: &str) -> Vec<Attribute> {
        self.attributes_elements(db)
            .into_iter()
            .filter(|a| a.attr(db).as_syntax_node().get_text_without_trivia(db) == attr)
            .collect()
    }

    /// Find first attribute named exactly `attr` attached do this node.
    fn find_attr(&self, db: &dyn SyntaxGroup, attr: &str) -> Option<Attribute> {
        self.query_attr(db, attr).into_iter().next()
    }

    /// Check if this node has an attribute named exactly `attr`.
    fn has_attr(&self, db: &dyn SyntaxGroup, attr: &str) -> bool {
        self.find_attr(db, attr).is_some()
    }

    /// Checks if the given object has an attribute with the given name and argument.
    fn has_attr_with_arg(&self, db: &dyn SyntaxGroup, attr_name: &str, arg_name: &str) -> bool {
        self.query_attr(db, attr_name).iter().any(|attr| is_single_arg_attr(db, attr, arg_name))
    }
}

impl QueryAttrs for ItemConstant {
    fn attributes_elements(&self, db: &dyn SyntaxGroup) -> Vec<Attribute> {
        self.attributes(db).elements(db)
    }
}
impl QueryAttrs for ItemModule {
    fn attributes_elements(&self, db: &dyn SyntaxGroup) -> Vec<Attribute> {
        self.attributes(db).elements(db)
    }
}
impl QueryAttrs for FunctionWithBody {
    fn attributes_elements(&self, db: &dyn SyntaxGroup) -> Vec<Attribute> {
        self.attributes(db).elements(db)
    }
}
impl QueryAttrs for ItemUse {
    fn attributes_elements(&self, db: &dyn SyntaxGroup) -> Vec<Attribute> {
        self.attributes(db).elements(db)
    }
}
impl QueryAttrs for ItemExternFunction {
    fn attributes_elements(&self, db: &dyn SyntaxGroup) -> Vec<Attribute> {
        self.attributes(db).elements(db)
    }
}
impl QueryAttrs for ItemExternType {
    fn attributes_elements(&self, db: &dyn SyntaxGroup) -> Vec<Attribute> {
        self.attributes(db).elements(db)
    }
}
impl QueryAttrs for ItemTrait {
    fn attributes_elements(&self, db: &dyn SyntaxGroup) -> Vec<Attribute> {
        self.attributes(db).elements(db)
    }
}
impl QueryAttrs for ItemImpl {
    fn attributes_elements(&self, db: &dyn SyntaxGroup) -> Vec<Attribute> {
        self.attributes(db).elements(db)
    }
}
impl QueryAttrs for ItemImplAlias {
    fn attributes_elements(&self, db: &dyn SyntaxGroup) -> Vec<Attribute> {
        self.attributes(db).elements(db)
    }
}
impl QueryAttrs for ItemStruct {
    fn attributes_elements(&self, db: &dyn SyntaxGroup) -> Vec<Attribute> {
        self.attributes(db).elements(db)
    }
}
impl QueryAttrs for ItemEnum {
    fn attributes_elements(&self, db: &dyn SyntaxGroup) -> Vec<Attribute> {
        self.attributes(db).elements(db)
    }
}
impl QueryAttrs for ItemTypeAlias {
    fn attributes_elements(&self, db: &dyn SyntaxGroup) -> Vec<Attribute> {
        self.attributes(db).elements(db)
    }
}
impl QueryAttrs for TraitItemFunction {
    fn attributes_elements(&self, db: &dyn SyntaxGroup) -> Vec<Attribute> {
        self.attributes(db).elements(db)
    }
}
impl QueryAttrs for TraitItem {
    fn attributes_elements(&self, db: &dyn SyntaxGroup) -> Vec<Attribute> {
        match self {
            TraitItem::Function(item) => item.attributes_elements(db),
            TraitItem::Missing(_) => vec![],
        }
    }
}

impl QueryAttrs for ItemInlineMacro {
    fn attributes_elements(&self, db: &dyn SyntaxGroup) -> Vec<Attribute> {
        self.attributes(db).elements(db)
    }
}

impl QueryAttrs for Item {
    fn attributes_elements(&self, db: &dyn SyntaxGroup) -> Vec<Attribute> {
        match self {
            Item::Constant(item) => item.attributes_elements(db),
            Item::Module(item) => item.attributes_elements(db),
            Item::FreeFunction(item) => item.attributes_elements(db),
            Item::Use(item) => item.attributes_elements(db),
            Item::ExternFunction(item) => item.attributes_elements(db),
            Item::ExternType(item) => item.attributes_elements(db),
            Item::Trait(item) => item.attributes_elements(db),
            Item::Impl(item) => item.attributes_elements(db),
            Item::ImplAlias(item) => item.attributes_elements(db),
            Item::Struct(item) => item.attributes_elements(db),
            Item::Enum(item) => item.attributes_elements(db),
            Item::TypeAlias(item) => item.attributes_elements(db),
            Item::InlineMacro(item) => item.attributes_elements(db),
            Item::Missing(_) => vec![],
        }
    }
}

impl QueryAttrs for ImplItem {
    fn attributes_elements(&self, db: &dyn SyntaxGroup) -> Vec<Attribute> {
        match self {
            ImplItem::Function(item) => item.attributes_elements(db),
            ImplItem::Constant(item) => item.attributes_elements(db),
            ImplItem::Module(item) => item.attributes_elements(db),
            ImplItem::Use(item) => item.attributes_elements(db),
            ImplItem::ExternFunction(item) => item.attributes_elements(db),
            ImplItem::ExternType(item) => item.attributes_elements(db),
            ImplItem::Trait(item) => item.attributes_elements(db),
            ImplItem::Impl(item) => item.attributes_elements(db),
            ImplItem::ImplAlias(item) => item.attributes_elements(db),
            ImplItem::Struct(item) => item.attributes_elements(db),
            ImplItem::Enum(item) => item.attributes_elements(db),
            ImplItem::TypeAlias(item) => item.attributes_elements(db),
            ImplItem::Missing(_) => vec![],
        }
    }
}

impl QueryAttrs for AttributeList {
    fn attributes_elements(&self, db: &dyn SyntaxGroup) -> Vec<Attribute> {
        self.elements(db)
    }
}
impl QueryAttrs for Member {
    fn attributes_elements(&self, db: &dyn SyntaxGroup) -> Vec<Attribute> {
        self.attributes(db).elements(db)
    }
}

impl QueryAttrs for Variant {
    fn attributes_elements(&self, db: &dyn SyntaxGroup) -> Vec<Attribute> {
        self.attributes(db).elements(db)
    }
}