//
// Cforall Version 1.0.0 Copyright (C) 2015 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// Actors.cpp -- generate code needed by the actor system
//
// Author           : Colby Parsons
// Created On       : Thurs Jan  19 15:34:00 2023
// Last Modified By : Colby Parsons
// Last Modified On : Thurs Jan  19 15:34:00 2023
// Update Count     : 0
//

#include "AST/Print.hpp"
#include "AST/Decl.hpp"
#include "AST/Pass.hpp"
#include "AST/Type.hpp"
#include "AST/Stmt.hpp"
#include "AST/TranslationUnit.hpp"
#include "AST/Expr.hpp"
#include <algorithm>
using namespace ast;
using namespace std;

namespace Concurrency {

struct CollectactorStructDecls : public ast::WithGuards {
	unordered_set<const StructDecl *> & actorStructDecls;
	unordered_set<const StructDecl *>  & messageStructDecls;
	const StructDecl ** requestDecl;
	const EnumDecl ** allocationDecl;
	const StructDecl ** actorDecl;
	const StructDecl ** msgDecl;
	StructDecl * parentDecl;
	bool insideStruct = false;
	bool namedDecl = false;

	// finds and sets a ptr to the allocation enum, which is needed in the next pass
	void previsit( const EnumDecl * decl ) {
		if( decl->name == "allocation" ) *allocationDecl = decl;
	}

	// finds and sets a ptr to the actor, message, and request structs, which are needed in the next pass
	void previsit( const StructDecl * decl ) {
		if ( !decl->body ) return;
		if ( decl->name == "actor" ) {
			actorStructDecls.insert( decl ); // skip inserting fwd decl
			*actorDecl = decl;
		} else if( decl->name == "message" ) {
			messageStructDecls.insert( decl ); // skip inserting fwd decl
			*msgDecl = decl;
		} else if( decl->name == "request" ) *requestDecl = decl;
		else {
			GuardValue(insideStruct);
			insideStruct = true;
			parentDecl = mutate( decl );
		}
	}

	// this catches structs of the form:
	//     struct dummy_actor { actor a; };
	// since they should be:
	//     struct dummy_actor { inline actor; };
	void previsit ( const ObjectDecl * decl ) {
		if ( insideStruct && ! decl->name.empty() ) {
			GuardValue(namedDecl);
			namedDecl = true;
		}
	}

	// this collects the derived actor and message struct decl ptrs
	void postvisit( const StructInstType * node ) {
		if ( ! *actorDecl || ! *msgDecl ) return;
		if ( insideStruct && !namedDecl ) {
			auto actorIter = actorStructDecls.find( node->aggr() );
			if ( actorIter != actorStructDecls.end() ) {
				actorStructDecls.insert( parentDecl );
				return;
			}
			auto messageIter = messageStructDecls.find( node->aggr() );
			if ( messageIter != messageStructDecls.end() ) {
				messageStructDecls.insert( parentDecl );
			}
		}
	}

  public:
	CollectactorStructDecls( unordered_set<const StructDecl *> & actorStructDecls, unordered_set<const StructDecl *> & messageStructDecls,
		const StructDecl ** requestDecl, const EnumDecl ** allocationDecl, const StructDecl ** actorDecl, const StructDecl ** msgDecl )
		: actorStructDecls( actorStructDecls ), messageStructDecls( messageStructDecls ), requestDecl( requestDecl ),
		allocationDecl( allocationDecl ), actorDecl(actorDecl), msgDecl(msgDecl) {}
};

// keeps track of all fwdDecls of message routines so that we can hoist them to right after the appropriate decls
class FwdDeclTable {

	// tracks which decls we have seen so that we can hoist the FunctionDecl to the highest point possible
	struct FwdDeclData {
		const StructDecl * actorDecl;
		const StructDecl * msgDecl;
		FunctionDecl * fwdDecl;
		bool actorFound;
		bool msgFound;

		bool readyToInsert() { return actorFound && msgFound; }
		bool foundActor() { actorFound = true; return readyToInsert(); }
		bool foundMsg() { msgFound = true; return readyToInsert(); }

		FwdDeclData( const StructDecl * actorDecl, const StructDecl * msgDecl, FunctionDecl * fwdDecl ) :
			actorDecl(actorDecl), msgDecl(msgDecl), fwdDecl(fwdDecl), actorFound(false), msgFound(false) {}
	};

	// map indexed by actor struct ptr
	// value is map of all FwdDeclData that contains said actor struct ptr
	// inner map is indexed by the message struct ptr of FwdDeclData
	unordered_map<const StructDecl *, unordered_map<const StructDecl *, FwdDeclData *>> actorMap;

	// this map is the same except the outer map is indexed by message ptr and the inner is indexed by actor ptr
	unordered_map<const StructDecl *, unordered_map<const StructDecl *, FwdDeclData *>> msgMap;

	void insert( const StructDecl * decl, const StructDecl * otherDecl, unordered_map<const StructDecl *, unordered_map<const StructDecl *, FwdDeclData *>> & map, FwdDeclData * data ) {
		auto iter = map.find( decl );
		if ( iter != map.end() ) { // if decl exists in map append data to existing inner map
			iter->second.emplace( make_pair( otherDecl, data ) );
		} else { // else create inner map for key
			map.emplace( make_pair( decl, unordered_map<const StructDecl *, FwdDeclData *>( { make_pair( otherDecl, data ) } ) ) );
		}
	}

  public:
	// insert decl into table so that we can fwd declare it later (average cost: O(1))
	void insertDecl( const StructDecl * actorDecl, const StructDecl * msgDecl, FunctionDecl * fwdDecl ) {
		FwdDeclData * declToInsert = new FwdDeclData( actorDecl, msgDecl, fwdDecl );
		insert( actorDecl, msgDecl, actorMap, declToInsert );
		insert( msgDecl, actorDecl, msgMap, declToInsert );
	}

	// returns list of decls to insert after current struct decl
	// Over the entire pass the runtime of this routine is O(r) where r is the # of receive routines
	list<FunctionDecl *> updateDecl( const StructDecl * decl, bool isMsg ) {
		unordered_map<const StructDecl *, unordered_map<const StructDecl *, FwdDeclData *>> & map = isMsg ? msgMap : actorMap;
		unordered_map<const StructDecl *, unordered_map<const StructDecl *, FwdDeclData *>> & otherMap =  isMsg ? actorMap : msgMap;
		auto iter = map.find( decl );
		list<FunctionDecl *> toInsertAfter; // this is populated with decls that are ready to insert
		if ( iter == map.end() ) return toInsertAfter;

		// iterate over inner map
		unordered_map<const StructDecl *, FwdDeclData *> & currInnerMap = iter->second;
		for ( auto innerIter = currInnerMap.begin(); innerIter != currInnerMap.end(); ) {
			FwdDeclData * currentDatum = innerIter->second;
			bool readyToInsert = isMsg ? currentDatum->foundMsg() : currentDatum->foundActor();
			if ( ! readyToInsert ) { ++innerIter; continue; }

			// readyToInsert is true so we are good to insert the forward decl of the message fn
			toInsertAfter.push_back( currentDatum->fwdDecl );

			// need to remove from other map before deleting
			// find inner map in other map ( other map is actor map if original is msg map and vice versa )
			const StructDecl * otherDecl = isMsg ? currentDatum->actorDecl : currentDatum->msgDecl;
			auto otherMapIter = otherMap.find( otherDecl );

			unordered_map<const StructDecl *, FwdDeclData *> & otherInnerMap = otherMapIter->second;

			// find the FwdDeclData we need to remove in the other inner map
			auto otherInnerIter = otherInnerMap.find( decl );

			// remove references to deleted FwdDeclData from current inner map
			innerIter = currInnerMap.erase( innerIter ); // this does the increment so no explicit inc needed

			// remove references to deleted FwdDeclData from other inner map
			otherInnerMap.erase( otherInnerIter );

			// if other inner map is now empty, remove key from other outer map
			if ( otherInnerMap.empty() )
				otherMap.erase( otherDecl );

			// now we are safe to delete the FwdDeclData since we are done with it
			// and we have removed all references to it from our data structures
			delete currentDatum;
		}

		// if current inner map is now empty, remove key from outer map.
		// Have to do this after iterating for safety
		if ( currInnerMap.empty() )
			map.erase( decl );

		return toInsertAfter;
	}
};

// generates the definitions of send operators for actors
// collects data needed for next pass that does the circular defn resolution
//     for message send operators (via table above)
struct GenFuncsCreateTables : public ast::WithDeclsToAdd {
	unordered_set<const StructDecl *> & actorStructDecls;
	unordered_set<const StructDecl *>  & messageStructDecls;
	const StructDecl ** requestDecl;
	const EnumDecl ** allocationDecl;
	const StructDecl ** actorDecl;
	const StructDecl ** msgDecl;
	FwdDeclTable & forwardDecls;

	// generates the operator for actor message sends
	void postvisit( const FunctionDecl * decl ) {
		// return if not of the form receive( param1, param2 ) or if it is a forward decl
		if ( decl->name != "receive" || decl->params.size() != 2 || !decl->stmts ) return;

		// the params should be references
		const ReferenceType * derivedActorRef = dynamic_cast<const ReferenceType *>(decl->params.at(0)->get_type());
		const ReferenceType * derivedMsgRef = dynamic_cast<const ReferenceType *>(decl->params.at(1)->get_type());
		if ( !derivedActorRef || !derivedMsgRef ) return;

		// the references should be to struct instances
		const StructInstType * arg1InstType = dynamic_cast<const StructInstType *>(derivedActorRef->base.get());
		const StructInstType * arg2InstType = dynamic_cast<const StructInstType *>(derivedMsgRef->base.get());
		if ( !arg1InstType || !arg2InstType ) return;

		// If the struct instances are derived actor and message types then generate the message send routine
		auto actorIter = actorStructDecls.find( arg1InstType->aggr() );
		auto messageIter = messageStructDecls.find( arg2InstType->aggr() );
		if ( actorIter != actorStructDecls.end() && messageIter != messageStructDecls.end() ) {
			//////////////////////////////////////////////////////////////////////
			// The following generates this wrapper for all receive(derived_actor &, derived_msg &) functions
			/* base_actor and base_msg are output params
			static inline allocation __CFA_receive_wrap( derived_actor & receiver, derived_msg & msg, actor ** base_actor, message ** base_msg ) {
				base_actor = &receiver;
				base_msg = &msg;
				return receive( receiver, msg );
			}
			*/
			CompoundStmt * wrapBody = new CompoundStmt( decl->location );

			// generates: base_actor = &receiver;
			wrapBody->push_back( new ExprStmt( decl->location,
				UntypedExpr::createAssign( decl->location,
					UntypedExpr::createDeref( decl->location, new NameExpr( decl->location, "base_actor" ) ),
					new AddressExpr( decl->location, new NameExpr( decl->location, "receiver" ) )
				)
			));

			// generates: base_msg = &msg;
			wrapBody->push_back( new ExprStmt( decl->location,
				UntypedExpr::createAssign( decl->location,
					UntypedExpr::createDeref( decl->location, new NameExpr( decl->location, "base_msg" ) ),
					new AddressExpr( decl->location, new NameExpr( decl->location, "msg" ) )
				)
			));

			// generates: return receive( receiver, msg );
			wrapBody->push_back( new ReturnStmt( decl->location,
				new UntypedExpr ( decl->location,
					new NameExpr( decl->location, "receive" ),
					{
						new NameExpr( decl->location, "receiver" ),
						new NameExpr( decl->location, "msg" )
					}
				)
			));

			// create receive wrapper to extract base message and actor pointer
			// put it all together into the complete function decl from above
			FunctionDecl * receiveWrapper = new FunctionDecl(
				decl->location,
				"__CFA_receive_wrap",
				{
					new ObjectDecl(
						decl->location,
						"receiver",
						ast::deepCopy( derivedActorRef )
					),
					new ObjectDecl(
						decl->location,
						"msg",
						ast::deepCopy( derivedMsgRef )
					),
					new ObjectDecl(
						decl->location,
						"base_actor",
						new PointerType( new PointerType( new StructInstType( *actorDecl ) ) )
					),
					new ObjectDecl(
						decl->location,
						"base_msg",
						new PointerType( new PointerType( new StructInstType( *msgDecl ) ) )
					)
				},                      // params
				{
					new ObjectDecl(
						decl->location,
						"__CFA_receive_wrap_ret",
						new EnumInstType( *allocationDecl )
					)
				},
				wrapBody,               // body
				{ Storage::Static },    // storage
				Linkage::Cforall,       // linkage
				{},                     // attributes
				{ Function::Inline }
			);

			declsToAddAfter.push_back( receiveWrapper );

			//////////////////////////////////////////////////////////////////////
			// The following generates this send message operator routine for all receive(derived_actor &, derived_msg &) functions
			/*
				static inline derived_actor & ?|?( derived_actor & receiver, derived_msg & msg ) {
					request new_req;
					allocation (*my_work_fn)( derived_actor &, derived_msg & ) = receive;
					__receive_fn fn = (__receive_fn)my_work_fn;
					new_req{ &receiver, &msg, fn };
					send( receiver, new_req );
					return receiver;
				}
			*/
			CompoundStmt * sendBody = new CompoundStmt( decl->location );

			// Generates: request new_req;
			sendBody->push_back( new DeclStmt(
				decl->location,
				new ObjectDecl(
					decl->location,
					"new_req",
					new StructInstType( *requestDecl )
				)
			));

			// Function type is: allocation (*)( derived_actor &, derived_msg &, actor **, message ** )
			FunctionType * derivedReceive = new FunctionType();
			derivedReceive->params.push_back( ast::deepCopy( derivedActorRef ) );
			derivedReceive->params.push_back( ast::deepCopy( derivedMsgRef ) );
			derivedReceive->params.push_back( new PointerType( new PointerType( new StructInstType( *actorDecl ) ) ) );
			derivedReceive->params.push_back( new PointerType( new PointerType( new StructInstType( *msgDecl ) ) ) );
			derivedReceive->returns.push_back( new EnumInstType( *allocationDecl ) );

			// Generates: allocation (*my_work_fn)( derived_actor &, derived_msg &, actor **, message ** ) = receive;
			sendBody->push_back( new DeclStmt(
				decl->location,
				new ObjectDecl(
					decl->location,
					"my_work_fn",
					new PointerType( derivedReceive ),
					new SingleInit( decl->location, new NameExpr( decl->location, "__CFA_receive_wrap" ) )
				)
			));

			// Function type is: allocation (*)( actor &, message & )
			FunctionType * genericReceive = new FunctionType();
			genericReceive->params.push_back( new ReferenceType( new StructInstType( *actorDecl ) ) );
			genericReceive->params.push_back( new ReferenceType( new StructInstType( *msgDecl ) ) );
			genericReceive->params.push_back( new PointerType( new PointerType( new StructInstType( *actorDecl ) ) ) );
			genericReceive->params.push_back( new PointerType( new PointerType( new StructInstType( *msgDecl ) ) ) );
			genericReceive->returns.push_back( new EnumInstType( *allocationDecl ) );

			// Generates: allocation (*fn)( actor &, message & ) = (allocation (*)( actor &, message & ))my_work_fn;
			// More readable synonymous code:
			//     typedef allocation (*__receive_fn)(actor &, message &);
			//     __receive_fn fn = (__receive_fn)my_work_fn;
			sendBody->push_back( new DeclStmt(
				decl->location,
				new ObjectDecl(
					decl->location,
					"fn",
					new PointerType( genericReceive ),
					new SingleInit( decl->location,
						new CastExpr( decl->location, new NameExpr( decl->location, "my_work_fn" ), new PointerType( genericReceive ), ExplicitCast )
					)
				)
			));

			// Generates: new_req{ (actor *)&receiver, (message *)&msg, fn };
			sendBody->push_back( new ExprStmt(
				decl->location,
				new UntypedExpr (
					decl->location,
					new NameExpr( decl->location, "?{}" ),
					{
						new NameExpr( decl->location, "new_req" ),
						new CastExpr( decl->location, new AddressExpr( new NameExpr( decl->location, "receiver" ) ), new PointerType( new StructInstType( *actorDecl ) ), ExplicitCast ),
						new CastExpr( decl->location, new AddressExpr( new NameExpr( decl->location, "msg" ) ), new PointerType( new StructInstType( *msgDecl ) ), ExplicitCast ),
						new NameExpr( decl->location, "fn" )
					}
				)
			));

			// Generates: send( receiver, new_req );
			sendBody->push_back( new ExprStmt(
				decl->location,
				new UntypedExpr (
					decl->location,
					new NameExpr( decl->location, "send" ),
					{
						{
							new NameExpr( decl->location, "receiver" ),
							new NameExpr( decl->location, "new_req" )
						}
					}
				)
			));

			// Generates: return receiver;
			sendBody->push_back( new ReturnStmt( decl->location, new NameExpr( decl->location, "receiver" ) ) );

			// put it all together into the complete function decl from above
			FunctionDecl * sendOperatorFunction = new FunctionDecl(
				decl->location,
				"?|?",
				{
					new ObjectDecl(
						decl->location,
						"receiver",
						ast::deepCopy( derivedActorRef )
					),
					new ObjectDecl(
						decl->location,
						"msg",
						ast::deepCopy( derivedMsgRef )
					)
				},                      // params
				{
					new ObjectDecl(
						decl->location,
						"receiver_ret",
						ast::deepCopy( derivedActorRef )
					)
				},
				nullptr,               // body
				{ Storage::Static },    // storage
				Linkage::Cforall,       // linkage
				{},                     // attributes
				{ Function::Inline }
			);

			// forward decls to resolve use before decl problem for '|' routines
			forwardDecls.insertDecl( *actorIter, *messageIter , ast::deepCopy( sendOperatorFunction ) );

			sendOperatorFunction->stmts = sendBody;
			declsToAddAfter.push_back( sendOperatorFunction );
		}
	}

  public:
	GenFuncsCreateTables( unordered_set<const StructDecl *> & actorStructDecls, unordered_set<const StructDecl *> & messageStructDecls,
		const StructDecl ** requestDecl, const EnumDecl ** allocationDecl, const StructDecl ** actorDecl, const StructDecl ** msgDecl,
		FwdDeclTable & forwardDecls ) : actorStructDecls(actorStructDecls), messageStructDecls(messageStructDecls),
		requestDecl(requestDecl), allocationDecl(allocationDecl), actorDecl(actorDecl), msgDecl(msgDecl), forwardDecls(forwardDecls) {}
};


// separate pass is needed since this pass resolves circular defn issues
// generates the forward declarations of the send operator for actor routines
struct FwdDeclOperator : public ast::WithDeclsToAdd {
	unordered_set<const StructDecl *> & actorStructDecls;
	unordered_set<const StructDecl *>  & messageStructDecls;
	FwdDeclTable & forwardDecls;

	// handles forward declaring the message operator
	void postvisit( const StructDecl * decl ) {
		list<FunctionDecl *> toAddAfter;
		auto actorIter = actorStructDecls.find( decl );
		if ( actorIter != actorStructDecls.end() ) { // this is a derived actor decl
			// get list of fwd decls that we can now insert
			toAddAfter = forwardDecls.updateDecl( decl, false );

			// get rid of decl from actorStructDecls since we no longer need it
			actorStructDecls.erase( actorIter );
		} else {
			auto messageIter = messageStructDecls.find( decl );
			if ( messageIter == messageStructDecls.end() ) return;

			toAddAfter = forwardDecls.updateDecl( decl, true );

			// get rid of decl from messageStructDecls since we no longer need it
			messageStructDecls.erase( messageIter );
		}

		// add the fwd decls to declsToAddAfter
		for ( FunctionDecl * func : toAddAfter ) {
			declsToAddAfter.push_back( func );
		}
	}

  public:
	FwdDeclOperator( unordered_set<const StructDecl *> & actorStructDecls, unordered_set<const StructDecl *> & messageStructDecls,
		FwdDeclTable & forwardDecls ) : actorStructDecls(actorStructDecls), messageStructDecls(messageStructDecls), forwardDecls(forwardDecls) {}
};

void implementActors( TranslationUnit & translationUnit ) {
	// unordered_maps to collect all derived actor and message types
	unordered_set<const StructDecl *> actorStructDecls;
	unordered_set<const StructDecl *> messageStructDecls;
	FwdDeclTable forwardDecls;

	// for storing through the passes
	// these are populated with various important struct decls
	const StructDecl * requestDeclPtr = nullptr;
	const EnumDecl * allocationDeclPtr = nullptr;
	const StructDecl * actorDeclPtr = nullptr;
	const StructDecl * msgDeclPtr = nullptr;

	// double pointer to modify local ptrs above
	const StructDecl ** requestDecl = &requestDeclPtr;
	const EnumDecl ** allocationDecl = &allocationDeclPtr;
	const StructDecl ** actorDecl = &actorDeclPtr;
	const StructDecl ** msgDecl = &msgDeclPtr;

	// first pass collects ptrs to allocation enum, request type, and generic receive fn typedef
	// also populates maps of all derived actors and messages
	Pass<CollectactorStructDecls>::run( translationUnit, actorStructDecls, messageStructDecls, requestDecl,
		allocationDecl, actorDecl, msgDecl );

	// check that we have found all the decls we need from <actor.hfa>, if not no need to run the rest of this pass
	if ( !allocationDeclPtr || !requestDeclPtr || !actorDeclPtr || !msgDeclPtr )
		return;

	// second pass locates all receive() routines that overload the generic receive fn
	// it then generates the appropriate operator '|' send routines for the receive routines
	Pass<GenFuncsCreateTables>::run( translationUnit, actorStructDecls, messageStructDecls, requestDecl,
		allocationDecl, actorDecl, msgDecl, forwardDecls );

	// The third pass forward declares operator '|' send routines
	Pass<FwdDeclOperator>::run( translationUnit, actorStructDecls, messageStructDecls, forwardDecls );
}

} // namespace Concurrency

// Local Variables: //
// tab-width: 4 //
// mode: c++ //
// compile-command: "make install" //
// End: //