(* This Source Code Form is subject to the terms of the Mozilla Public License,
  v. 2.0. If a copy of the MPL was not distributed with this file, You can
  obtain one at https://mozilla.org/MPL/2.0/. *)
module
import common, lexer, ast, symbol, diagnostic

proc elna_type_is_aggregate*(_type: ^ElnaType) -> Bool
var
	result: Bool := false
begin
	if _type <> nil then
		result := _type^.kind = ElnaTypeKind._record or _type^.kind = ElnaTypeKind.array
	end
return result

proc elna_type_character_literal(parser_node: ^ElnaTreeCharacterLiteral)
begin
	parser_node^.type_decoration := char_type
return

proc elna_type_integer_literal(parser_node: ^ElnaTreeIntegerLiteral)
begin
	parser_node^.type_decoration := word_type
return

proc elna_type_string_literal(parser_node: ^ElnaTreeStringLiteral)
begin
	parser_node^.type_decoration := cast(string_type: ^ElnaType)
return

proc elna_type_boolean_literal(parser_node: ^ElnaTreeBooleanLiteral)
begin
	parser_node^.type_decoration := bool_type
return

proc elna_type_nil_literal(parser_node: ^ElnaTreeNilLiteral)
begin
	parser_node^.type_decoration := pointer_type
return

proc elna_type_variable_expression(parser_node: ^ElnaTreeVariableExpression; symbol_table: ^ElnaSymbolTable)
var
	variable_info: ^ElnaSymbolInfo
	temporary_info: ^ElnaSymbolTemporaryInfo
	procedure_info: ^ElnaSymbolProcedureInfo
begin
	variable_info := elna_symbol_table_lookup(symbol_table, parser_node^.name);
	if variable_info <> nil then
		if variable_info^.kind = ElnaSymbolInfoKind.temporary_info then
			temporary_info := cast(variable_info: ^ElnaSymbolTemporaryInfo);
			parser_node^.type_decoration := temporary_info^.variable_type
		elsif variable_info^.kind = ElnaSymbolInfoKind.procedure_info then
			procedure_info := cast(variable_info: ^ElnaSymbolProcedureInfo);
			parser_node^.type_decoration := cast(procedure_info^.procedure_type: ^ElnaType)
		end
	end
return

proc elna_type_cast_expression(parser_node: ^ElnaTreeCastExpression; symbol_table: ^ElnaSymbolTable;
		error_list: ^ElnaList)
begin
	elna_type_binary_expression(parser_node^.expression, symbol_table, error_list)
return

proc elna_type_call(parser_node: ^ElnaTreeCall; symbol_table: ^ElnaSymbolTable; error_list: ^ElnaList)
var
	argument_tree: ^ElnaTreeExpressionList
	procedure_type: ^ElnaTypeProcedure
begin
	argument_tree := parser_node^.arguments;

	elna_type_variable_expression(parser_node^.callee, symbol_table);
	if parser_node^.callee^.type_decoration <> nil & parser_node^.callee^.type_decoration^.kind = ElnaTypeKind.procedure then
		procedure_type := cast(parser_node^.callee^.type_decoration: ^ElnaTypeProcedure);
		parser_node^.type_decoration := procedure_type^.return_type
	end;

	while argument_tree <> nil do
		elna_type_binary_expression(argument_tree^.expression, symbol_table, error_list);
		argument_tree := argument_tree^.next
	end
return

proc elna_type_dereference_expression(parser_node: ^ElnaTreeDereferenceExpression; symbol_table: ^ElnaSymbolTable;
		error_list: ^ElnaList)
var
	base_type: ^ElnaType := nil
	pointer_type_node: ^ElnaTypePointer
begin
	elna_type_designator(parser_node^.pointer, symbol_table, error_list);

	if parser_node^.pointer^.type_decoration <> nil then
		base_type := parser_node^.pointer^.type_decoration;
		if base_type^.kind = ElnaTypeKind.pointer then
			pointer_type_node := cast(base_type: ^ElnaTypePointer);
			base_type := pointer_type_node^.base
		end
	end;
	parser_node^.type_decoration := base_type
return

proc elna_type_field_access_expression(parser_node: ^ElnaTreeFieldAccessExpression; symbol_table: ^ElnaSymbolTable;
		error_list: ^ElnaList)
var
	variable_expression: ^ElnaTreeVariableExpression
	base_type: ^ElnaType := nil
	type_kind: ^ElnaSymbolTypeInfo
	symbol_info: ^ElnaSymbolInfo
	aggregate_type: ^ElnaTypeRecord
	field_count: Word
	current_field: ^ElnaTypeField
begin
	if parser_node^.aggregate^.kind = ElnaTreeKind.variable_expression then
		variable_expression := cast(parser_node^.aggregate: ^ElnaTreeVariableExpression);
		symbol_info := elna_symbol_table_lookup(symbol_table_global, variable_expression^.name);
		if symbol_info <> nil & symbol_info^.kind = ElnaSymbolInfoKind.type_info then
			type_kind := cast(symbol_info: ^ElnaSymbolTypeInfo);
			base_type := type_kind^._type
		end
	end;

	if base_type = nil then
		elna_type_designator(parser_node^.aggregate, symbol_table, error_list);
		if parser_node^.aggregate^.type_decoration <> nil & parser_node^.aggregate^.type_decoration^.kind = ElnaTypeKind._record then
			aggregate_type := cast(parser_node^.aggregate^.type_decoration: ^ElnaTypeRecord);
			field_count := aggregate_type^.length;
			current_field := aggregate_type^.members;

			while field_count > 0u & base_type = nil do
				if current_field^.name = parser_node^.field then
					base_type := current_field^.field_type
				else
					field_count := field_count - 1u;
					current_field := current_field + 1u
				end
			end
		end
	end;

	parser_node^.type_decoration := base_type
return

proc elna_type_array_access_expression(parser_node: ^ElnaTreeArrayAccessExpression; symbol_table: ^ElnaSymbolTable;
		error_list: ^ElnaList)
var
	aggregate_type: ^ElnaTypeArray
begin
	elna_type_designator(parser_node^.array, symbol_table, error_list);
	elna_type_binary_expression(parser_node^.index, symbol_table, error_list);

	if parser_node^.array^.type_decoration <> nil & parser_node^.array^.type_decoration^.kind = ElnaTypeKind.array then
		aggregate_type := cast(parser_node^.array^.type_decoration: ^ElnaTypeArray);
		parser_node^.type_decoration := aggregate_type^.base
	end
return

proc elna_type_simple_expression(parser_node: ^ElnaTreeExpression; symbol_table: ^ElnaSymbolTable; error_list: ^ElnaList)
begin
	case parser_node^.kind of
		ElnaTreeKind.integer_literal:
			elna_type_integer_literal(cast(parser_node: ^ElnaTreeIntegerLiteral))
		| ElnaTreeKind.character_literal:
			elna_type_character_literal(cast(parser_node: ^ElnaTreeCharacterLiteral))
		| ElnaTreeKind.string_literal:
			elna_type_string_literal(cast(parser_node: ^ElnaTreeStringLiteral))
		| ElnaTreeKind.boolean_literal:
			elna_type_boolean_literal(cast(parser_node: ^ElnaTreeBooleanLiteral))
		| ElnaTreeKind.null:
			elna_type_nil_literal(cast(parser_node: ^ElnaTreeNilLiteral))
		| ElnaTreeKind._cast:
			elna_type_cast_expression(cast(parser_node: ^ElnaTreeCastExpression), symbol_table, error_list)
		| ElnaTreeKind.variable_expression:
			elna_type_variable_expression(cast(parser_node: ^ElnaTreeVariableExpression), symbol_table)
		else
	end
return

proc elna_type_designator(parser_node: ^ElnaTreeExpression; symbol_table: ^ElnaSymbolTable; error_list: ^ElnaList)
begin
	case parser_node^.kind of
		ElnaTreeKind.dereference_expression:
			elna_type_dereference_expression(cast(parser_node: ^ElnaTreeDereferenceExpression), symbol_table, error_list)
		| ElnaTreeKind.field_access_expression:
			elna_type_field_access_expression(cast(parser_node: ^ElnaTreeFieldAccessExpression), symbol_table, error_list)
		| ElnaTreeKind.array_access_expression:
			elna_type_array_access_expression(cast(parser_node: ^ElnaTreeArrayAccessExpression), symbol_table, error_list)
		| ElnaTreeKind.call:
			elna_type_call(cast(parser_node: ^ElnaTreeCall), symbol_table, error_list)
		else
			elna_type_simple_expression(parser_node, symbol_table, error_list)
	end
return

proc elna_type_unary_expression(parser_node: ^ElnaTreeExpression; symbol_table: ^ElnaSymbolTable;
		error_list: ^ElnaList)
var
	unary_node: ^ElnaTreeUnaryExpression
begin
	if parser_node^.kind = ElnaTreeKind.unary_expression then
		unary_node := cast(parser_node: ^ElnaTreeUnaryExpression);
		elna_type_designator(unary_node^.operand, symbol_table, error_list);
		parser_node^.type_decoration := unary_node^.operand^.type_decoration
	else
		elna_type_designator(parser_node, symbol_table, error_list)
	end
return

proc elna_type_binary_expression(parser_node: ^ElnaTreeExpression; symbol_table: ^ElnaSymbolTable;
		error_list: ^ElnaList)
var
	binary_node: ^ElnaTreeBinaryExpression
begin
	if parser_node <> nil then
		if parser_node^.kind = ElnaTreeKind.binary_expression then
			binary_node := cast(parser_node: ^ElnaTreeBinaryExpression);
			elna_type_unary_expression(binary_node^.rhs, symbol_table, error_list);
			elna_type_unary_expression(binary_node^.lhs, symbol_table, error_list);
			parser_node^.type_decoration := binary_node^.lhs^.type_decoration
		else
			elna_type_unary_expression(parser_node, symbol_table, error_list)
		end
	end
return

proc elna_type_assign_statement(parser_node: ^ElnaTreeAssignStatement; symbol_table: ^ElnaSymbolTable;
		error_list: ^ElnaList)
begin
	elna_type_designator(parser_node^.assignee, symbol_table, error_list);
	elna_type_binary_expression(parser_node^.assignment, symbol_table, error_list)
return

proc elna_type_conditional_statements(parser_node: ^ElnaTreeConditionalStatements; symbol_table: ^ElnaSymbolTable;
		error_list: ^ElnaList)
var
	current: ^ElnaTreeConditionalStatements
begin
	current := parser_node;
	while current <> nil do
		elna_type_binary_expression(current^.condition, symbol_table, error_list);
		elna_type_statements(current^.statements, symbol_table, error_list);
		current := current^.next
	end
return

proc elna_type_if_statement(parser_node: ^ElnaTreeIfStatement; symbol_table: ^ElnaSymbolTable; error_list: ^ElnaList)
begin
	elna_type_conditional_statements(parser_node^.conditionals, symbol_table, error_list);
	if parser_node^._else <> nil then
		elna_type_statements(parser_node^._else, symbol_table, error_list)
	end
return

proc elna_type_return_statement(parser_node: ^ElnaTreeReturnStatement; symbol_table: ^ElnaSymbolTable; error_list: ^ElnaList)
begin
	if parser_node^.returned <> nil then
		elna_type_binary_expression(parser_node^.returned, symbol_table, error_list)
	end
return

proc elna_type_statement(parser_node: ^ElnaTreeStatement; symbol_table: ^ElnaSymbolTable; error_list: ^ElnaList)
var
	call_statement: ^ElnaTreeCallStatement
begin
	case parser_node^.kind of
		ElnaTreeKind.if_statement:
			elna_type_if_statement(cast(parser_node: ^ElnaTreeIfStatement), symbol_table, error_list)
		| ElnaTreeKind.return_statement:
			elna_type_return_statement(cast(parser_node: ^ElnaTreeReturnStatement), symbol_table, error_list)
		| ElnaTreeKind.call_statement:
			call_statement := cast(parser_node: ^ElnaTreeCallStatement);
			elna_type_call(call_statement^.call, symbol_table, error_list)
		| ElnaTreeKind.assign_statement:
			elna_type_assign_statement(cast(parser_node: ^ElnaTreeAssignStatement), symbol_table, error_list)
		else
	end
return

proc elna_type_statements(parser_node: ^ElnaTreeStatement; symbol_table: ^ElnaSymbolTable; error_list: ^ElnaList)
var
	current: ^ElnaTreeStatement
begin
	current := parser_node;
	while current <> nil do
		elna_type_statement(current, symbol_table, error_list);
		current := current^.next
	end
return

proc elna_type_procedure_declaration(parser_node: ^ElnaTreeProcedureDeclaration; error_list: ^ElnaList)
var
	procedure_info: ^ElnaSymbolProcedureInfo
	symbol_info: ^ElnaSymbolInfo
begin
	symbol_info := elna_symbol_table_lookup(symbol_table_global, parser_node^.name);
	if symbol_info <> nil & symbol_info^.kind = ElnaSymbolInfoKind.procedure_info then
		procedure_info := cast(symbol_info: ^ElnaSymbolProcedureInfo);
		elna_type_statements(parser_node^.body, procedure_info^.symbol_table, error_list)
	end
return

proc elna_type_module_declaration*(parser_node: ^ElnaTreeModuleDeclaration; error_list: ^ElnaList)
var
	current_proc: ^ElnaTreeProcedureDeclaration
begin
	current_proc := parser_node^.procedures;
	while current_proc <> nil do
		elna_type_procedure_declaration(current_proc, error_list);
		current_proc := cast(current_proc^.next: ^ElnaTreeProcedureDeclaration)
	end;
	if parser_node^.body <> nil then
		elna_type_statements(parser_node^.body, symbol_table_global, error_list)
	end
return

end.