//
// 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.
//
// CurrentObject.h --
//
// Author           : Rob Schluntz
// Created On       : Tue Jun 13 15:28:32 2017
// Last Modified By : Andrew Beach
// Last Modified On : Mon Apr 10  9:40:00 2023
// Update Count     : 18
//

#include <stddef.h>                    // for size_t
#include <cassert>                     // for assertf, assert, safe_dynamic_...
#include <deque>
#include <iostream>                    // for ostream, operator<<, basic_ost...
#include <stack>                       // for stack
#include <string>                      // for string, operator<<, allocator

#include "AST/Copy.hpp"                // for shallowCopy
#include "AST/Expr.hpp"                // for InitAlternative
#include "AST/GenericSubstitution.hpp" // for genericSubstitution
#include "AST/Init.hpp"                // for Designation
#include "AST/Node.hpp"                // for readonly
#include "AST/Print.hpp"               // for readonly
#include "AST/Type.hpp"
#include "Common/Eval.h"               // for eval
#include "Common/Indenter.h"           // for Indenter, operator<<
#include "Common/SemanticError.h"      // for SemanticError
#include "Common/utility.h"            // for toString
#include "CurrentObject.h"

#if 0
#define PRINT(x) x
#else
#define PRINT(x)
#endif

namespace ast {
	/// Iterates members of a type by initializer.
	class MemberIterator {
	public:
		virtual ~MemberIterator() {}

		/// Internal set position based on iterator ranges.
		virtual void setPosition(
			std::deque< ptr< Expr > >::const_iterator it,
			std::deque< ptr< Expr > >::const_iterator end ) = 0;

		/// Walks the current object using the given designators as a guide.
		void setPosition( const std::deque< ptr< Expr > > & designators ) {
			setPosition( designators.begin(), designators.end() );
		}

		/// Retrieve the list of possible (Type,Designation) pairs for the
		/// current position in the current object.
		virtual std::deque< InitAlternative > operator* () const = 0;

		/// True if the iterator is not currently at the end.
		virtual operator bool() const = 0;

		/// Moves the iterator by one member in the current object.
		virtual MemberIterator & bigStep() = 0;

		/// Moves the iterator by one member in the current subobject.
		virtual MemberIterator & smallStep() = 0;

		/// The type of the current object.
		virtual const Type * getType() = 0;

		/// The type of the current subobject.
		virtual const Type * getNext() = 0;

		/// Helper for operator*; aggregates must add designator to each init
		/// alternative, but adding designators in operator* creates duplicates.
		virtual std::deque< InitAlternative > first() const = 0;
	};

	/// create a new MemberIterator that traverses a type correctly
	MemberIterator * createMemberIterator( const CodeLocation & loc, const Type * type );

	/// Iterates "other" types (e.g. basic, pointer) which do not change at list initializer entry
	class SimpleIterator final : public MemberIterator {
		CodeLocation location;
		const Type * type = nullptr;
	public:
		SimpleIterator( const CodeLocation & loc, const Type * t ) : location( loc ), type( t ) {}

		void setPosition(
			std::deque< ptr< Expr > >::const_iterator begin,
			std::deque< ptr< Expr > >::const_iterator end
		) override {
			if ( begin != end ) {
				SemanticError( location, "Un-designated initializer given non-empty designator" );
			}
		}

		std::deque< InitAlternative > operator* () const override { return first(); }

		operator bool() const override { return type; }

		SimpleIterator & bigStep() override { return smallStep(); }
		SimpleIterator & smallStep() override {
			type = nullptr;  // empty on increment because no members
			return *this;
		}

		const Type * getType() override { return type; }

		const Type * getNext() override { return type; }

		std::deque< InitAlternative > first() const override {
			if ( type ) return { InitAlternative{ type, new Designation{ location } } };
			return {};
		}
	};

	/// Iterates over an indexed type:
	class IndexIterator : public MemberIterator {
	protected:
		CodeLocation location;
		size_t index = 0;
		size_t size = 0;
		std::unique_ptr<MemberIterator> memberIter;
	public:
		IndexIterator( const CodeLocation & loc, size_t size ) :
			location( loc ), size( size )
		{}

		void setPosition( const Expr * expr ) {
			// need to permit integer-constant-expressions, including: integer constants,
			// enumeration constants, character constants, sizeof expressions, alignof expressions,
			// cast expressions

			auto arg = eval( expr );
			assertf( arg.hasKnownValue, "Non-evaluable expression made it to IndexIterator" );
			index = arg.knownValue;

			// if ( auto constExpr = dynamic_cast< const ConstantExpr * >( expr ) ) {
			// 	try {
			// 		index = constExpr->intValue();
			// 	} catch ( SemanticErrorException & ) {
			// 		SemanticError( expr, "Constant expression of non-integral type in array designator: " );
			// 	}
			// } else if ( auto castExpr = dynamic_cast< const CastExpr * >( expr ) ) {
			// 	setPosition( castExpr->arg );
			// } else if ( dynamic_cast< const SizeofExpr * >( expr ) || dynamic_cast< const AlignofExpr * >( expr ) ) {
			// 	index = 0;
			// } else {
			// 	assertf( false,	"2 bad designator given to ArrayIterator: %s", toString( expr ).c_str() );
			// }
		}

		void setPosition(
			std::deque<ast::ptr<ast::Expr>>::const_iterator begin,
			std::deque<ast::ptr<ast::Expr>>::const_iterator end
		) override {
			if ( begin == end ) return;

			setPosition( *begin );
			memberIter->setPosition( ++begin, end );
		}

		std::deque< InitAlternative > operator* () const override { return first(); }

		operator bool() const override { return index < size; }
	};

	/// Iterates over the members of array types:
	class ArrayIterator final : public IndexIterator {
		const ArrayType * array = nullptr;
		const Type * base = nullptr;

		size_t getSize( const Expr * expr ) {
			auto res = eval( expr );
			if ( !res.hasKnownValue ) {
				SemanticError( location, toString( "Array designator must be a constant expression: ", expr ) );
			}
			return res.knownValue;
		}

	public:
		ArrayIterator( const CodeLocation & loc, const ArrayType * at ) :
				IndexIterator( loc, getSize( at->dimension) ),
				array( at ), base( at->base ) {
			PRINT( std::cerr << "Creating array iterator: " << at << std::endl; )
			memberIter.reset( createMemberIterator( loc, base ) );
			if ( at->isVarLen ) {
				SemanticError( location, at, "VLA initialization does not support @=: " );
			}
		}

		ArrayIterator & bigStep() override {
			PRINT( std::cerr << "bigStep in ArrayIterator (" << index << "/" << size << ")" << std::endl; )
			++index;
			memberIter.reset( index < size ? createMemberIterator( location, base ) : nullptr );
			return *this;
		}

		ArrayIterator & smallStep() override {
			PRINT( std::cerr << "smallStep in ArrayIterator (" << index << "/" << size << ")" << std::endl; )
			if ( memberIter ) {
				PRINT( std::cerr << "has member iter: " << *memberIter << std::endl; )
				memberIter->smallStep();
				if ( *memberIter ) {
					PRINT( std::cerr << "has valid member iter" << std::endl; )
					return *this;
				}
			}
			return bigStep();
		}

		const Type * getType() override { return array; }

		const Type * getNext() override { return base; }

		std::deque< InitAlternative > first() const override {
			PRINT( std::cerr << "first in ArrayIterator (" << index << "/" << size << ")" << std::endl; )
			if ( memberIter && *memberIter ) {
				std::deque< InitAlternative > ret = memberIter->first();
				for ( InitAlternative & alt : ret ) {
					alt.designation.get_and_mutate()->designators.emplace_front( ConstantExpr::from_ulong( location, index ) );
				}
				return ret;
			}
			return {};
		}
	};

	class AggregateIterator : public MemberIterator {
	protected:
		using MemberList = std::vector< ptr< Decl > >;

		CodeLocation location;
		std::string kind;  // for debug
		std::string name;
		const Type * inst;
		const MemberList & members;
		MemberList::const_iterator curMember;
		bool atbegin = true;  // false at first {small,big}Step
		const Type * curType = nullptr;
		std::unique_ptr< MemberIterator > memberIter = nullptr;
		TypeSubstitution sub;

		bool init() {
			PRINT( std::cerr << "--init()--" << members.size() << std::endl; )
			if ( curMember != members.end() ) {
				if ( auto field = curMember->as< ObjectDecl >() ) {
					PRINT( std::cerr << "incremented to field: " << field << std::endl; )
					curType = field->get_type();
					memberIter.reset( createMemberIterator( location, curType ) );
					return true;
				}
			}
			return false;
		}

		AggregateIterator(
			const CodeLocation & loc, const std::string k, const std::string & n, const Type * i,
			const MemberList & ms )
		: location( loc ), kind( k ), name( n ), inst( i ), members( ms ), curMember( ms.begin() ),
		  sub( genericSubstitution( i ) ) {
			PRINT( std::cerr << "Creating " << kind << "(" << name << ")"; )
			init();
		}

	public:
		void setPosition(
			std::deque< ptr< Expr > >::const_iterator begin,
			std::deque< ptr< Expr > >::const_iterator end
		) final {
			if ( begin == end ) return;

			if ( auto varExpr = begin->as< VariableExpr >() ) {
				for ( curMember = members.begin(); curMember != members.end(); ++curMember ) {
					if ( *curMember != varExpr->var ) continue;

					++begin;

					memberIter.reset( createMemberIterator( location, varExpr->result ) );
					curType = varExpr->result;
					atbegin = curMember == members.begin() && begin == end;
					memberIter->setPosition( begin, end );
					return;
				}
				assertf( false, "could not find member in %s: %s", kind.c_str(), toString( varExpr ).c_str() );
			} else {
				assertf( false, "1 bad designator given to %s: %s", kind.c_str(), toString( *begin ).c_str() );
			}
		}

		std::deque< InitAlternative > operator* () const final {
			if ( memberIter && *memberIter ) {
				std::deque< InitAlternative > ret = memberIter->first();
				PRINT( std::cerr << "sub: " << sub << std::endl; )
				for ( InitAlternative & alt : ret ) {
					PRINT( std::cerr << "iterating and adding designators" << std::endl; )
					alt.designation.get_and_mutate()->designators.emplace_front(
						new VariableExpr{ location, curMember->strict_as< ObjectDecl >() } );
					// need to substitute for generic types so that casts are to concrete types
					alt.type = shallowCopy(alt.type.get());
					PRINT( std::cerr << "  type is: " << alt.type; )
					sub.apply( alt.type ); // also apply to designation??
					PRINT( std::cerr << " ==> " << alt.type << std::endl; )
				}
				return ret;
			}
			return {};
		}

		AggregateIterator & smallStep() final {
			PRINT( std::cerr << "smallStep in " << kind << std::endl; )
			atbegin = false;
			if ( memberIter ) {
				PRINT( std::cerr << "has member iter, incrementing..." << std::endl; )
				memberIter->smallStep();
				if ( *memberIter ) {
					PRINT( std::cerr << "success!" << std::endl; )
					return *this;
				}
			}
			return bigStep();
		}

		AggregateIterator & bigStep() override = 0;

		const Type * getType() final { return inst; }

		const Type * getNext() final {
			bool hasMember = memberIter && *memberIter;
			return hasMember ? memberIter->getType() : nullptr;
		}

		std::deque< InitAlternative > first() const final {
			std::deque< InitAlternative > ret;
			PRINT( std::cerr << "first " << kind << std::endl; )
			if ( memberIter && *memberIter ) {
				PRINT( std::cerr << "adding children" << std::endl; )
				ret = memberIter->first();
				for ( InitAlternative & alt : ret ) {
					PRINT( std::cerr << "iterating and adding designators" << std::endl; )
					alt.designation.get_and_mutate()->designators.emplace_front(
						new VariableExpr{ location, curMember->strict_as< ObjectDecl >() } );
				}
			}
			if ( atbegin ) {
				// only add self if at the very beginning of the structure
				PRINT( std::cerr << "adding self" << std::endl; )
				ret.emplace_front( inst, new Designation{ location } );
			}
			return ret;
		}
	};

	class StructIterator final : public AggregateIterator {
	public:
		StructIterator( const CodeLocation & loc, const StructInstType * inst )
		: AggregateIterator( loc, "StructIterator", inst->name, inst, inst->base->members ) {}

		operator bool() const override {
			return curMember != members.end() || (memberIter && *memberIter);
		}

		StructIterator & bigStep() override {
			PRINT( std::cerr << "bigStep in " << kind << std::endl; )
			atbegin = false;
			memberIter = nullptr;
			curType = nullptr;
			while ( curMember != members.end() ) {
				++curMember;
				if ( init() ) return *this;
			}
			return *this;
		}
	};

	class UnionIterator final : public AggregateIterator {
	public:
		UnionIterator( const CodeLocation & loc, const UnionInstType * inst )
		: AggregateIterator( loc, "UnionIterator", inst->name, inst, inst->base->members ) {}

		operator bool() const override { return memberIter && *memberIter; }

		UnionIterator & bigStep() override {
			// unions only initialize one member
			PRINT( std::cerr << "bigStep in " << kind << std::endl; )
			atbegin = false;
			memberIter = nullptr;
			curType = nullptr;
			curMember = members.end();
			return *this;
		}
	};

	/// Iterates across the positions in a tuple:
	class TupleIterator final : public IndexIterator {
		ast::TupleType const * const tuple;

		const ast::Type * typeAtIndex() const {
			assert( index < size );
			return tuple->types[ index ].get();
		}

	public:
		TupleIterator( const CodeLocation & loc, const TupleType * type )
		: IndexIterator( loc, type->size() ), tuple( type ) {
			PRINT( std::cerr << "Creating tuple iterator: " << type << std::endl; )
			memberIter.reset( createMemberIterator( loc, typeAtIndex() ) );
		}

		TupleIterator & bigStep() override {
			++index;
			memberIter.reset( index < size ?
				createMemberIterator( location, typeAtIndex() ) : nullptr );
			return *this;
		}

		TupleIterator & smallStep() override {
			if ( memberIter ) {
				PRINT( std::cerr << "has member iter: " << *memberIter << std::endl; )
				memberIter->smallStep();
				if ( !memberIter ) {
					PRINT( std::cerr << "has valid member iter" << std::endl; )
					return *this;
				}
			}
			return bigStep();
		}

		const ast::Type * getType() override {
			return tuple;
		}

		const ast::Type * getNext() override {
			bool hasMember = memberIter && *memberIter;
			return hasMember ? memberIter->getType() : nullptr;
		}

		std::deque< InitAlternative > first() const override {
			PRINT( std::cerr << "first in TupleIterator (" << index << "/" << size << ")" << std::endl; )
			if ( memberIter && *memberIter ) {
				std::deque< InitAlternative > ret = memberIter->first();
				for ( InitAlternative & alt : ret ) {
					alt.designation.get_and_mutate()->designators.emplace_front(
						ConstantExpr::from_ulong( location, index ) );
				}
				return ret;
			}
			return {};
		}
	};

	MemberIterator * createMemberIterator( const CodeLocation & loc, const Type * type ) {
		if ( auto aggr = dynamic_cast< const BaseInstType * >( type ) ) {
			if ( auto sit = dynamic_cast< const StructInstType * >( aggr ) ) {
				assert( sit->base );
				return new StructIterator{ loc, sit };
			} else if ( auto uit = dynamic_cast< const UnionInstType * >( aggr ) ) {
				assert( uit->base );
				return new UnionIterator{ loc, uit };
			} else {
				assertf(
					dynamic_cast< const EnumInstType * >( type )
						|| dynamic_cast< const TypeInstType * >( type ),
					"Encountered unhandled BaseInstType in createMemberIterator: %s",
						toString( type ).c_str() );
				return new SimpleIterator{ loc, type };
			}
		} else if ( auto at = dynamic_cast< const ArrayType * >( type ) ) {
			return new ArrayIterator{ loc, at };
		} else if ( auto tt = dynamic_cast< const TupleType * >( type ) ) {
			return new TupleIterator{ loc, tt };
		} else {
			return new SimpleIterator{ loc, type };
		}
	}

	CurrentObject::CurrentObject( const CodeLocation & loc, const Type * type ) : objStack() {
		objStack.emplace_back( new SimpleIterator{ loc, type } );
	}

	const Designation * CurrentObject::findNext( const Designation * designation ) {
		using DesignatorChain = std::deque< ptr< Expr > >;
		PRINT( std::cerr << "___findNext" << std::endl; )

		// find all the d's
		std::vector< DesignatorChain > desigAlts{ {} }, newDesigAlts;
		std::deque< const Type * > curTypes{ objStack.back()->getType() }, newTypes;
		for ( const Expr * expr : designation->designators ) {
			PRINT( std::cerr << "____untyped: " << expr << std::endl; )
			auto dit = desigAlts.begin();

			for ( const Type * t : curTypes ) {
				assert( dit != desigAlts.end() );
				DesignatorChain & d = *dit;
				if ( auto nexpr = dynamic_cast< const NameExpr *>( expr ) ) {
					PRINT( std::cerr << "____actual: " << t << std::endl; )
					if ( auto refType = dynamic_cast< const BaseInstType * >( t ) ) {
						// concatenate identical field names
						for ( const Decl * mem : refType->lookup( nexpr->name ) ) {
							if ( auto field = dynamic_cast< const ObjectDecl * >( mem ) ) {
								PRINT( std::cerr << "____alt: " << field->type << std::endl; )
								DesignatorChain d2 = d;
								d2.emplace_back( new VariableExpr{ expr->location, field } );
								newDesigAlts.emplace_back( std::move( d2 ) );
								newTypes.emplace_back( field->type );
							}
						}
					} else if ( auto at = dynamic_cast< const ArrayType * >( t ) ) {
						auto nexpr = dynamic_cast< const NameExpr *>( expr );
						for ( const Decl * mem : refType->lookup( nexpr->name ) ) {
							if ( auto field = dynamic_cast< const ObjectDecl * >( mem ) ) {
								DesignatorChain d2 = d;
								d2.emplace_back( new VariableExpr{ expr->location, field } );
								newDesigAlts.emplace_back( std::move( d2 ) );
								newTypes.emplace_back( at->base );
							}
						}
					}

					++dit;
				} else {
					if ( auto at = dynamic_cast< const ArrayType * >( t ) ) {
						PRINT( std::cerr << "____alt: " << at->get_base() << std::endl; )
						d.emplace_back( expr );
						newDesigAlts.emplace_back( d );
						newTypes.emplace_back( at->base );
					}
				}
			}

			// reset queue
			desigAlts = std::move( newDesigAlts );
			newDesigAlts.clear();
			curTypes = std::move( newTypes );
			newTypes.clear();
			assertf( desigAlts.size() == curTypes.size(), "Designator alternatives (%zu) and current types (%zu) out of sync", desigAlts.size(), curTypes.size() );
		}

		if ( desigAlts.size() > 1 ) {
			SemanticError( designation, toString("Too many alternatives (", desigAlts.size(), ") for designation: ") );
		} else if ( desigAlts.empty() ) {
			SemanticError( designation, "No reasonable alternatives for designation: " );
		}

		DesignatorChain & d = desigAlts.back();
		PRINT( for ( Expression * expr : d ) {
			std::cerr << "____desig: " << expr << std::endl;
		} ) // for
		assertf( ! curTypes.empty(), "empty designator chosen");

		// set new designators
		assertf( ! objStack.empty(), "empty object stack when setting designation" );
		Designation * actualDesignation =
			new Designation{ designation->location, DesignatorChain{d} };
		objStack.back()->setPosition( d ); // destroys d
		return actualDesignation;
	}

	void CurrentObject::setNext( const Designation * designation ) {
		PRINT( std::cerr << "____setNext" << designation << std::endl; )
		assertf( ! objStack.empty(), "obj stack empty in setNext" );
		objStack.back()->setPosition( designation->designators );
	}

	void CurrentObject::increment() {
		PRINT( std::cerr << "____increment" << std::endl; )
		if ( objStack.empty() ) return;
		PRINT( std::cerr << *objStack.back() << std::endl; )
		objStack.back()->smallStep();
	}

	void CurrentObject::enterListInit( const CodeLocation & loc ) {
		PRINT( std::cerr << "____entering list init" << std::endl; )
		assertf( ! objStack.empty(), "empty obj stack entering list init" );
		const ast::Type * type = objStack.back()->getNext();
		assert( type );
		objStack.emplace_back( createMemberIterator( loc, type ) );
	}

	void CurrentObject::exitListInit() {
		PRINT( std::cerr << "____exiting list init" << std::endl; )
		assertf( ! objStack.empty(), "objstack empty" );
		objStack.pop_back();
		if ( ! objStack.empty() ) {
			PRINT( std::cerr << *objStack.back() << std::endl; )
			objStack.back()->bigStep();
		}
	}

	std::deque< InitAlternative > CurrentObject::getOptions() {
		PRINT( std::cerr << "____getting current options" << std::endl; )
		assertf( ! objStack.empty(), "objstack empty in getOptions" );
		return **objStack.back();
	}

	const Type * CurrentObject::getCurrentType() {
		PRINT( std::cerr << "____getting current type" << std::endl; )
		assertf( ! objStack.empty(), "objstack empty in getCurrentType" );
		return objStack.back()->getNext();
	}
}

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