//! HIR (previsouly known as descriptors) provides a high-level OO acess to Rust
//! code.
//!
//! The principal difference between HIR and syntax trees is that HIR is bound
//! to a particular crate instance. That is, it has cfg flags and features
//! applied. So, there relation between syntax and HIR is many-to-one.

macro_rules! ctry {
    ($expr:expr) => {
        match $expr {
            None => return Ok(None),
            Some(it) => it,
        }
    };
}

pub mod db;
#[cfg(test)]
mod mock;
mod query_definitions;
mod path;
mod arena;
pub mod source_binder;

mod macros;
mod name;
mod krate;
mod module;
mod function;
mod adt;
mod type_ref;
mod ty;

use std::ops::Index;

use ra_syntax::{SyntaxNodeRef, SyntaxNode, SyntaxKind, SourceFile, AstNode, ast};
use ra_db::{LocationIntener, SourceRootId, FileId, Cancelable};

use crate::{
    db::HirDatabase,
    arena::{Arena, Id},
    name::{AsName, KnownName},
};

pub use self::{
    path::{Path, PathKind},
    name::Name,
    krate::Crate,
    macros::{MacroDef, MacroInput, MacroExpansion, MacroCallId, MacroCallLoc},
    module::{Module, ModuleId, Problem, nameres::{ItemMap, PerNs, Namespace}, ModuleScope, Resolution},
    function::{Function, FnScopes},
    adt::{Struct, Enum},
    ty::Ty,
};

pub use self::function::FnSignatureInfo;

/// An `MFileId` is like a `FileId`, but it can also refer to code generated by
/// macros.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub enum MFileId {
    File(FileId),
    Macro(MacroCallId),
}

impl From<FileId> for MFileId {
    fn from(file_id: FileId) -> MFileId {
        MFileId::File(file_id)
    }
}

/// Def's are a core concept of hir. A `Def` is an Item (function, module, etc)
/// in a specific module.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub struct DefId(u32);
ra_db::impl_numeric_id!(DefId);

#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
pub(crate) enum DefKind {
    Module,
    Function,
    Struct,
    Enum,
    Item,

    StructCtor,
}

#[derive(Clone, Debug, PartialEq, Eq, Hash)]
pub struct DefLoc {
    pub(crate) kind: DefKind,
    source_root_id: SourceRootId,
    module_id: ModuleId,
    source_item_id: SourceItemId,
}

impl DefKind {
    pub(crate) fn for_syntax_kind(kind: SyntaxKind) -> PerNs<DefKind> {
        match kind {
            SyntaxKind::FN_DEF => PerNs::values(DefKind::Function),
            SyntaxKind::MODULE => PerNs::types(DefKind::Module),
            SyntaxKind::STRUCT_DEF => PerNs::both(DefKind::Struct, DefKind::StructCtor),
            SyntaxKind::ENUM_DEF => PerNs::types(DefKind::Enum),
            // These define items, but don't have their own DefKinds yet:
            SyntaxKind::TRAIT_DEF => PerNs::types(DefKind::Item),
            SyntaxKind::TYPE_DEF => PerNs::types(DefKind::Item),
            SyntaxKind::CONST_DEF => PerNs::values(DefKind::Item),
            SyntaxKind::STATIC_DEF => PerNs::values(DefKind::Item),
            _ => PerNs::none(),
        }
    }
}

impl DefId {
    pub(crate) fn loc(self, db: &impl AsRef<LocationIntener<DefLoc, DefId>>) -> DefLoc {
        db.as_ref().id2loc(self)
    }
}

impl DefLoc {
    pub(crate) fn id(&self, db: &impl AsRef<LocationIntener<DefLoc, DefId>>) -> DefId {
        db.as_ref().loc2id(&self)
    }
}

pub enum Def {
    Module(Module),
    Function(Function),
    Struct(Struct),
    Enum(Enum),
    Item,
}

impl DefId {
    pub fn resolve(self, db: &impl HirDatabase) -> Cancelable<Def> {
        let loc = self.loc(db);
        let res = match loc.kind {
            DefKind::Module => {
                let module = Module::new(db, loc.source_root_id, loc.module_id)?;
                Def::Module(module)
            }
            DefKind::Function => {
                let function = Function::new(self);
                Def::Function(function)
            }
            DefKind::Struct => {
                let struct_def = Struct::new(self);
                Def::Struct(struct_def)
            }
            DefKind::Enum => {
                let enum_def = Enum::new(self);
                Def::Enum(enum_def)
            }
            DefKind::StructCtor => Def::Item,
            DefKind::Item => Def::Item,
        };
        Ok(res)
    }

    /// For a module, returns that module; for any other def, returns the containing module.
    pub fn module(self, db: &impl HirDatabase) -> Cancelable<Module> {
        let loc = self.loc(db);
        Module::new(db, loc.source_root_id, loc.module_id)
    }
}

/// Identifier of item within a specific file. This is stable over reparses, so
/// it's OK to use it as a salsa key/value.
pub(crate) type SourceFileItemId = Id<SyntaxNode>;

#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub struct SourceItemId {
    mfile_id: MFileId,
    /// None for the whole file.
    item_id: Option<SourceFileItemId>,
}

/// Maps item's `SyntaxNode`s to `SourceFileItemId` and back.
#[derive(Debug, PartialEq, Eq)]
pub struct SourceFileItems {
    mfile_id: MFileId,
    arena: Arena<SyntaxNode>,
}

impl SourceFileItems {
    fn new(mfile_id: MFileId, source_file: SourceFile) -> SourceFileItems {
        let mut res = SourceFileItems {
            mfile_id,
            arena: Arena::default(),
        };
        res.init(source_file);
        res
    }

    fn init(&mut self, source_file: SourceFile) {
        source_file.syntax().descendants().for_each(|it| {
            if let Some(module_item) = ast::ModuleItem::cast(it) {
                self.alloc(module_item.syntax().owned());
            } else if let Some(macro_call) = ast::MacroCall::cast(it) {
                self.alloc(macro_call.syntax().owned());
            }
        });
    }

    fn alloc(&mut self, item: SyntaxNode) -> SourceFileItemId {
        self.arena.alloc(item)
    }
    pub fn id_of(&self, mfile_id: MFileId, item: SyntaxNodeRef) -> SourceFileItemId {
        assert_eq!(
            self.mfile_id, mfile_id,
            "SourceFileItems: wrong file, expected {:?}, got {:?}",
            self.mfile_id, mfile_id
        );
        self.id_of_unchecked(item)
    }
    fn id_of_unchecked(&self, item: SyntaxNodeRef) -> SourceFileItemId {
        if let Some((id, _)) = self.arena.iter().find(|(_id, i)| i.borrowed() == item) {
            return id;
        }
        // This should not happen. Let's try to give a sensible diagnostics.
        if let Some((id, i)) = self.arena.iter().find(|(_id, i)| i.range() == item.range()) {
            // FIXME(#288): whyyy are we getting here?
            log::error!(
                "unequal syntax nodes with the same range:\n{:?}\n{:?}",
                item,
                i
            );
            return id;
        }
        panic!(
            "Can't find {:?} in SourceFileItems:\n{:?}",
            item,
            self.arena.iter().map(|(_id, i)| i).collect::<Vec<_>>(),
        );
    }
    pub fn id_of_source_file(&self) -> SourceFileItemId {
        let (id, _syntax) = self.arena.iter().next().unwrap();
        id
    }
}

impl Index<SourceFileItemId> for SourceFileItems {
    type Output = SyntaxNode;
    fn index(&self, idx: SourceFileItemId) -> &SyntaxNode {
        &self.arena[idx]
    }
}