//! `SourceBinder` is the main entry point for getting info about source code.
//! It's main task is to map source syntax trees to hir-level IDs.

use hir_def::{
    child_by_source::ChildBySource,
    dyn_map::DynMap,
    keys::{self, Key},
    ConstId, DefWithBodyId, EnumId, EnumVariantId, FunctionId, GenericDefId, ImplId, ModuleId,
    StaticId, StructFieldId, StructId, TraitId, TypeAliasId, TypeParamId, UnionId, VariantId,
};
use hir_expand::{name::AsName, AstId, InFile, MacroDefId, MacroDefKind};
use ra_db::FileId;
use ra_prof::profile;
use ra_syntax::{
    ast::{self, NameOwner},
    match_ast, AstNode, SyntaxNode,
};
use rustc_hash::FxHashMap;

use crate::{db::HirDatabase, Module};

pub(crate) struct SourceBinder {
    child_by_source_cache: FxHashMap<ChildContainer, DynMap>,
}

impl SourceBinder {
    pub(crate) fn new() -> SourceBinder {
        SourceBinder { child_by_source_cache: FxHashMap::default() }
    }

    pub(crate) fn to_module_def(&mut self, db: &impl HirDatabase, file: FileId) -> Option<Module> {
        let _p = profile("SourceBinder::to_module_def");
        let (krate, local_id) = db.relevant_crates(file).iter().find_map(|&crate_id| {
            let crate_def_map = db.crate_def_map(crate_id);
            let local_id = crate_def_map.modules_for_file(file).next()?;
            Some((crate_id, local_id))
        })?;
        Some(Module { id: ModuleId { krate, local_id } })
    }

    pub(crate) fn to_id<T: ToId>(
        &mut self,
        db: &impl HirDatabase,
        src: InFile<T>,
    ) -> Option<T::ID> {
        T::to_id(db, self, src)
    }

    pub(crate) fn find_container(
        &mut self,
        db: &impl HirDatabase,
        src: InFile<&SyntaxNode>,
    ) -> Option<ChildContainer> {
        for container in src.cloned().ancestors_with_macros(db).skip(1) {
            let res: ChildContainer = match_ast! {
                match (container.value) {
                    ast::TraitDef(it) => {
                        let def: TraitId = self.to_id(db, container.with_value(it))?;
                        def.into()
                    },
                    ast::ImplBlock(it) => {
                        let def: ImplId = self.to_id(db, container.with_value(it))?;
                        def.into()
                    },
                    ast::FnDef(it) => {
                        let def: FunctionId = self.to_id(db, container.with_value(it))?;
                        DefWithBodyId::from(def).into()
                    },
                    ast::StaticDef(it) => {
                        let def: StaticId = self.to_id(db, container.with_value(it))?;
                        DefWithBodyId::from(def).into()
                    },
                    ast::ConstDef(it) => {
                        let def: ConstId = self.to_id(db, container.with_value(it))?;
                        DefWithBodyId::from(def).into()
                    },
                    ast::EnumDef(it) => {
                        let def: EnumId = self.to_id(db, container.with_value(it))?;
                        def.into()
                    },
                    ast::StructDef(it) => {
                        let def: StructId = self.to_id(db, container.with_value(it))?;
                        VariantId::from(def).into()
                    },
                    ast::UnionDef(it) => {
                        let def: UnionId = self.to_id(db, container.with_value(it))?;
                        VariantId::from(def).into()
                    },
                    ast::Module(it) => {
                        let def: ModuleId = self.to_id(db, container.with_value(it))?;
                        def.into()
                    },
                    _ => { continue },
                }
            };
            return Some(res);
        }

        let c = self.to_module_def(db, src.file_id.original_file(db))?;
        Some(c.id.into())
    }

    fn child_by_source(&mut self, db: &impl HirDatabase, container: ChildContainer) -> &DynMap {
        self.child_by_source_cache.entry(container).or_insert_with(|| match container {
            ChildContainer::DefWithBodyId(it) => it.child_by_source(db),
            ChildContainer::ModuleId(it) => it.child_by_source(db),
            ChildContainer::TraitId(it) => it.child_by_source(db),
            ChildContainer::ImplId(it) => it.child_by_source(db),
            ChildContainer::EnumId(it) => it.child_by_source(db),
            ChildContainer::VariantId(it) => it.child_by_source(db),
            ChildContainer::GenericDefId(it) => it.child_by_source(db),
        })
    }
}

pub(crate) trait ToId: Sized {
    type ID: Sized + Copy + 'static;
    fn to_id<DB: HirDatabase>(
        db: &DB,
        sb: &mut SourceBinder,
        src: InFile<Self>,
    ) -> Option<Self::ID>;
}

#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
pub(crate) enum ChildContainer {
    DefWithBodyId(DefWithBodyId),
    ModuleId(ModuleId),
    TraitId(TraitId),
    ImplId(ImplId),
    EnumId(EnumId),
    VariantId(VariantId),
    /// XXX: this might be the same def as, for example an `EnumId`. However,
    /// here the children generic parameters, and not, eg enum variants.
    GenericDefId(GenericDefId),
}
impl_froms! {
    ChildContainer:
    DefWithBodyId,
    ModuleId,
    TraitId,
    ImplId,
    EnumId,
    VariantId,
    GenericDefId
}

pub(crate) trait ToIdByKey: Sized + AstNode + 'static {
    type ID: Sized + Copy + 'static;
    const KEY: Key<Self, Self::ID>;
}

impl<T: ToIdByKey> ToId for T {
    type ID = <T as ToIdByKey>::ID;
    fn to_id<DB: HirDatabase>(
        db: &DB,
        sb: &mut SourceBinder,
        src: InFile<Self>,
    ) -> Option<Self::ID> {
        let container = sb.find_container(db, src.as_ref().map(|it| it.syntax()))?;
        let dyn_map =
            &*sb.child_by_source_cache.entry(container).or_insert_with(|| match container {
                ChildContainer::DefWithBodyId(it) => it.child_by_source(db),
                ChildContainer::ModuleId(it) => it.child_by_source(db),
                ChildContainer::TraitId(it) => it.child_by_source(db),
                ChildContainer::ImplId(it) => it.child_by_source(db),
                ChildContainer::EnumId(it) => it.child_by_source(db),
                ChildContainer::VariantId(it) => it.child_by_source(db),
                ChildContainer::GenericDefId(it) => it.child_by_source(db),
            });
        dyn_map[T::KEY].get(&src).copied()
    }
}

macro_rules! to_id_key_impls {
    ($(($id:ident, $ast:path, $key:path)),* ,) => {$(
        impl ToIdByKey for $ast {
            type ID = $id;
            const KEY: Key<Self, Self::ID> = $key;
        }
    )*}
}

to_id_key_impls![
    (StructId, ast::StructDef, keys::STRUCT),
    (UnionId, ast::UnionDef, keys::UNION),
    (EnumId, ast::EnumDef, keys::ENUM),
    (TraitId, ast::TraitDef, keys::TRAIT),
    (FunctionId, ast::FnDef, keys::FUNCTION),
    (StaticId, ast::StaticDef, keys::STATIC),
    (ConstId, ast::ConstDef, keys::CONST),
    (TypeAliasId, ast::TypeAliasDef, keys::TYPE_ALIAS),
    (ImplId, ast::ImplBlock, keys::IMPL),
    (StructFieldId, ast::RecordFieldDef, keys::RECORD_FIELD),
    (EnumVariantId, ast::EnumVariant, keys::ENUM_VARIANT),
];

// FIXME: use DynMap as well?
impl ToId for ast::MacroCall {
    type ID = MacroDefId;
    fn to_id<DB: HirDatabase>(
        db: &DB,
        sb: &mut SourceBinder,
        src: InFile<Self>,
    ) -> Option<Self::ID> {
        let kind = MacroDefKind::Declarative;

        let krate = sb.to_module_def(db, src.file_id.original_file(db))?.id.krate;

        let ast_id = Some(AstId::new(src.file_id, db.ast_id_map(src.file_id).ast_id(&src.value)));

        Some(MacroDefId { krate: Some(krate), ast_id, kind })
    }
}

impl ToId for ast::TypeParam {
    type ID = TypeParamId;

    fn to_id<DB: HirDatabase>(
        db: &DB,
        sb: &mut SourceBinder,
        src: InFile<Self>,
    ) -> Option<Self::ID> {
        let file_id = src.file_id;
        let parent: GenericDefId = src.value.syntax().ancestors().find_map(|it| {
            let res = match_ast! {
                match it {
                    ast::FnDef(value) => { sb.to_id(db, InFile { value, file_id})?.into() },
                    ast::StructDef(value) => { sb.to_id(db, InFile { value, file_id})?.into() },
                    ast::EnumDef(value) => { sb.to_id(db, InFile { value, file_id})?.into() },
                    ast::TraitDef(value) => { sb.to_id(db, InFile { value, file_id})?.into() },
                    ast::TypeAliasDef(value) => { sb.to_id(db, InFile { value, file_id})?.into() },
                    ast::ImplBlock(value) => { sb.to_id(db, InFile { value, file_id})?.into() },
                    _ => return None,
                }
            };
            Some(res)
        })?;
        sb.child_by_source(db, parent.into())[keys::TYPE_PARAM].get(&src).copied()
    }
}

impl ToId for ast::Module {
    type ID = ModuleId;

    fn to_id<DB: HirDatabase>(
        db: &DB,
        sb: &mut SourceBinder,
        src: InFile<ast::Module>,
    ) -> Option<ModuleId> {
        {
            let _p = profile("ast::Module::to_def");
            let parent_declaration = src
                .as_ref()
                .map(|it| it.syntax())
                .cloned()
                .ancestors_with_macros(db)
                .skip(1)
                .find_map(|it| {
                    let m = ast::Module::cast(it.value.clone())?;
                    Some(it.with_value(m))
                });

            let parent_module = match parent_declaration {
                Some(parent_declaration) => sb.to_id(db, parent_declaration)?,
                None => {
                    let file_id = src.file_id.original_file(db);
                    sb.to_module_def(db, file_id)?.id
                }
            };

            let child_name = src.value.name()?.as_name();
            let def_map = db.crate_def_map(parent_module.krate);
            let child_id = *def_map[parent_module.local_id].children.get(&child_name)?;
            Some(ModuleId { krate: parent_module.krate, local_id: child_id })
        }
    }
}