use std::sync::Arc;

use relative_path::RelativePathBuf;
use ra_db::{CrateId, Cancelable, FileId};
use ra_syntax::{ast, TreePtr, SyntaxNode};

use crate::{Name, db::HirDatabase, DefId, Path, PerNs, nameres::ModuleScope, adt::VariantData};

/// hir::Crate describes a single crate. It's the main inteface with which
/// crate's dependencies interact. Mostly, it should be just a proxy for the
/// root module.
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub struct Crate {
    pub(crate) crate_id: CrateId,
}

#[derive(Debug)]
pub struct CrateDependency {
    pub krate: Crate,
    pub name: Name,
}

impl Crate {
    pub fn crate_id(&self) -> CrateId {
        self.crate_id
    }
    pub fn dependencies(&self, db: &impl HirDatabase) -> Cancelable<Vec<CrateDependency>> {
        Ok(self.dependencies_impl(db))
    }
    pub fn root_module(&self, db: &impl HirDatabase) -> Cancelable<Option<Module>> {
        self.root_module_impl(db)
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub struct Module {
    pub(crate) def_id: DefId,
}

pub enum ModuleSource {
    SourceFile(TreePtr<ast::SourceFile>),
    Module(TreePtr<ast::Module>),
}

#[derive(Clone, Debug, Hash, PartialEq, Eq)]
pub enum Problem {
    UnresolvedModule {
        candidate: RelativePathBuf,
    },
    NotDirOwner {
        move_to: RelativePathBuf,
        candidate: RelativePathBuf,
    },
}

impl Module {
    /// Name of this module.
    pub fn name(&self, db: &impl HirDatabase) -> Cancelable<Option<Name>> {
        self.name_impl(db)
    }

    /// Returns a node which defines this module. That is, a file or a `mod foo {}` with items.
    pub fn defenition_source(&self, db: &impl HirDatabase) -> Cancelable<(FileId, ModuleSource)> {
        self.defenition_source_impl(db)
    }
    /// Returns a node which declares this module, either a `mod foo;` or a `mod foo {}`.
    /// `None` for the crate root.
    pub fn declaration_source(
        &self,
        db: &impl HirDatabase,
    ) -> Cancelable<Option<(FileId, TreePtr<ast::Module>)>> {
        self.declaration_source_impl(db)
    }

    /// Returns the crate this module is part of.
    pub fn krate(&self, db: &impl HirDatabase) -> Cancelable<Option<Crate>> {
        self.krate_impl(db)
    }
    /// Topmost parent of this module. Every module has a `crate_root`, but some
    /// might miss `krate`. This can happen if a module's file is not included
    /// into any module tree of any target from Cargo.toml.
    pub fn crate_root(&self, db: &impl HirDatabase) -> Cancelable<Module> {
        self.crate_root_impl(db)
    }
    /// Finds a child module with the specified name.
    pub fn child(&self, db: &impl HirDatabase, name: &Name) -> Cancelable<Option<Module>> {
        self.child_impl(db, name)
    }
    /// Finds a parent module.
    pub fn parent(&self, db: &impl HirDatabase) -> Cancelable<Option<Module>> {
        self.parent_impl(db)
    }
    pub fn path_to_root(&self, db: &impl HirDatabase) -> Cancelable<Vec<Module>> {
        let mut res = vec![self.clone()];
        let mut curr = self.clone();
        while let Some(next) = curr.parent(db)? {
            res.push(next.clone());
            curr = next
        }
        Ok(res)
    }
    /// Returns a `ModuleScope`: a set of items, visible in this module.
    pub fn scope(&self, db: &impl HirDatabase) -> Cancelable<ModuleScope> {
        self.scope_impl(db)
    }
    pub fn resolve_path(&self, db: &impl HirDatabase, path: &Path) -> Cancelable<PerNs<DefId>> {
        self.resolve_path_impl(db, path)
    }
    pub fn problems(
        &self,
        db: &impl HirDatabase,
    ) -> Cancelable<Vec<(TreePtr<SyntaxNode>, Problem)>> {
        self.problems_impl(db)
    }
}

pub struct Struct {
    pub(crate) def_id: DefId,
}

impl Struct {
    pub fn def_id(&self) -> DefId {
        self.def_id
    }

    pub fn variant_data(&self, db: &impl HirDatabase) -> Cancelable<Arc<VariantData>> {
        Ok(self.struct_data(db)?.variant_data.clone())
    }

    pub fn name(&self, db: &impl HirDatabase) -> Cancelable<Option<Name>> {
        Ok(self.struct_data(db)?.name.clone())
    }
}