/* valadatatype.vala
 *
 * Copyright (C) 2006-2010  Jürg Billeter
 * Copyright (C) 2006-2008  Raffaele Sandrini
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.

 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.

 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
 *
 * Author:
 * 	Jürg Billeter <j@bitron.ch>
 *	Raffaele Sandrini <raffaele@sandrini.ch>
 */

using GLib;

/**
 * A reference to a data type. This is used to specify static types of
 * expressions.
 */
public abstract class Vala.DataType : CodeNode {
	/**
	 * Specifies that the expression or variable owns the value.
	 */
	public bool value_owned { get; set; }

	/**
	 * Specifies that the expression may be null.
	 */
	public bool nullable { get; set; }

	/**
	 * The referred symbol.
	 */
	public weak Symbol? symbol { get; private set; }

	/**
	 * The referred symbol in the current context.
	 */
	public weak Symbol? context_symbol { get; set; }

	/**
	 * The referred type symbol.
	 */
	public weak TypeSymbol? type_symbol {
		get {
			return symbol as TypeSymbol;
		}
	}

	/**
	 * Specifies that the expression transfers a floating reference.
	 */
	public bool floating_reference { get; set; }

	/**
	 * Specifies that the type supports dynamic lookup.
	 */
	public bool is_dynamic { get; set; }

	private List<DataType> type_argument_list;
	private static List<DataType> _empty_type_list;

	protected DataType.with_symbol (Symbol? symbol, SourceReference? source_reference = null) {
		this.symbol = symbol;
		this.source_reference = source_reference;
	}

	/**
	 * Appends the specified type as generic type argument.
	 *
	 * @param arg a type reference
	 */
	public void add_type_argument (DataType arg) {
		if (type_argument_list == null) {
			type_argument_list = new ArrayList<DataType> ();
		}
		type_argument_list.add (arg);
		arg.parent_node = this;
	}

	/**
	 * Returns the list of generic type arguments.
	 *
	 * @return type argument list
	 */
	public unowned List<DataType> get_type_arguments () {
		if (type_argument_list != null) {
			return type_argument_list;
		}
		if (_empty_type_list == null) {
			_empty_type_list = new ArrayList<DataType> ();
		}
		return _empty_type_list;
	}

	public bool has_type_arguments () {
		if (type_argument_list == null) {
			return false;
		}

		return type_argument_list.size > 0;
	}

	/**
	 * Removes all generic type arguments.
	 */
	public void remove_all_type_arguments () {
		type_argument_list = null;
	}

	public override void accept (CodeVisitor visitor) {
		visitor.visit_data_type (this);
	}

	public override void accept_children (CodeVisitor visitor) {
		if (type_argument_list != null && type_argument_list.size > 0) {
			foreach (DataType type_arg in type_argument_list) {
				type_arg.accept (visitor);
			}
		}
	}

	public override string to_string () {
		return to_qualified_string (null);
	}

	public virtual string to_qualified_string (Scope? scope = null) {
		string s;

		if (type_symbol != null) {
			Symbol global_symbol = type_symbol;
			while (global_symbol.parent_symbol != null && global_symbol.parent_symbol.name != null) {
				global_symbol = global_symbol.parent_symbol;
			}

			Symbol sym = null;
			Scope parent_scope = scope;
			while (sym == null && parent_scope != null) {
				sym = parent_scope.lookup (global_symbol.name);
				parent_scope = parent_scope.parent_scope;
			}

			if (sym != null && global_symbol != sym) {
				s = "global::" + type_symbol.get_full_name ();;
			} else {
				s = type_symbol.get_full_name ();
			}
		} else {
			s = "null";
		}

		var type_args = get_type_arguments ();
		if (type_args.size > 0) {
			s += "<";
			bool first = true;
			foreach (DataType type_arg in type_args) {
				if (!first) {
					s += ",";
				} else {
					first = false;
				}
				if (type_arg.is_weak ()) {
					s += "weak ";
				}
				s += type_arg.to_qualified_string (scope);
			}
			s += ">";
		}
		if (nullable) {
			s += "?";
		}

		return s;
	}

	/**
	 * Creates a shallow copy of this type reference.
	 *
	 * @return copy of this type reference
	 */
	public abstract DataType copy ();

	/**
	 * Checks two type references for equality. May only be used with
	 * resolved type references.
	 *
	 * @param type2 a type reference
	 * @return      true if this type reference is equal to type2, false
	 *              otherwise
	 */
	public virtual bool equals (DataType type2) {
		if (type2.is_disposable () != is_disposable ()) {
			return false;
		}
		if (type2.nullable != nullable) {
			//TODO Allow equality between nullable and non-nullable generic-types
			// This mitigation allows fixing affected source code without breaking it.
			// It has to be removed at some point
			var context = CodeContext.get ();
			return !context.experimental_non_null && this is GenericType == type2 is GenericType;
		}
		if (type2.type_symbol != type_symbol) {
			return false;
		}
		if (type2 is GenericType || this is GenericType) {
			if (!(type2 is GenericType) || !(this is GenericType)) {
				return false;
			}
			if (!((GenericType) type2).type_parameter.equals (((GenericType) this).type_parameter)) {
				return false;
			}
		}
		if (type2.floating_reference != floating_reference) {
			return false;
		}

		var type_args = get_type_arguments ();
		var type2_args = type2.get_type_arguments ();
		if (type2_args.size != type_args.size) {
			return false;
		}

		for (int i = 0; i < type_args.size; i++) {
			if (!type2_args[i].equals (type_args[i]))
				return false;
		}

		return true;
	}

	/**
	 * Checks whether this type reference is at least as strict as the
	 * specified type reference type2.
	 *
	 * @param type2 a type reference
	 * @return      true if this type reference is stricter or equal
	 */
	public virtual bool stricter (DataType type2) {
		if (type2.is_disposable () != is_disposable ()) {
			return false;
		}

		if (!type2.nullable && nullable) {
			return false;
		}

		/* temporarily ignore type parameters */
		if (this is GenericType || type2 is GenericType) {
			return true;
		}

		if (type2.type_symbol != type_symbol) {
			// FIXME: allow this type reference to refer to a
			//        subtype of the type type2 is referring to
			return false;
		}

		if (type2.floating_reference != floating_reference) {
			return false;
		}

		return true;
	}

	public override void replace_type (DataType old_type, DataType new_type) {
		if (type_argument_list != null) {
			for (int i = 0; i < type_argument_list.size; i++) {
				if (type_argument_list[i] == old_type) {
					type_argument_list[i] = new_type;
					return;
				}
			}
		}
	}

	public virtual bool compatible (DataType target_type) {
		var context = CodeContext.get ();

		if (context.experimental_non_null && nullable && !target_type.nullable) {
			return false;
		}

		if (context.profile == Profile.GOBJECT && target_type.type_symbol != null) {
			unowned DataType? gvalue_type = context.analyzer.gvalue_type;
			if (gvalue_type != null && target_type.type_symbol.is_subtype_of (gvalue_type.type_symbol)) {
				// allow implicit conversion to GValue
				return true;
			}

			unowned DataType? gvariant_type = context.analyzer.gvariant_type;
			if (gvariant_type != null && target_type.type_symbol.is_subtype_of (gvariant_type.type_symbol)) {
				// allow implicit conversion to GVariant
				return true;
			}
		}

		if (target_type is PointerType) {
			/* any reference or array type or pointer type can be cast to a generic pointer */
			if (this is GenericType ||
				(type_symbol != null && (
					type_symbol.is_reference_type () ||
					this is DelegateType))) {
				return true;
			}

			return false;
		}

		/* temporarily ignore type parameters */
		if (target_type is GenericType) {
			return true;
		}

		if (this is ArrayType != target_type is ArrayType) {
			return false;
		}

		if (type_symbol is Enum && target_type.type_symbol is Struct && ((Struct) target_type.type_symbol).is_integer_type ()) {
			return true;
		} else if (target_type.type_symbol is Enum && type_symbol is Struct && ((Struct) type_symbol).is_integer_type ()) {
			//FIXME Drop this unsafe direction in the future?
			return true;
		}

		// check for matching ownership of type-arguments
		var type_args = get_type_arguments ();
		var target_type_args = target_type.get_type_arguments ();
		if (type_args.size == target_type_args.size) {
			for (int i = 0; i < type_args.size; i++) {
				var type_arg = type_args[i];
				var target_type_arg = target_type_args[i];
				// Ignore non-boxed simple-type structs
				if (!type_arg.is_non_null_simple_type ()
				    && type_arg.is_weak () != target_type_arg.is_weak ()) {
					return false;
				}
			}
		}

		if (type_symbol != null && target_type.type_symbol != null && type_symbol.is_subtype_of (target_type.type_symbol)) {
			var base_type = SemanticAnalyzer.get_instance_base_type_for_member(this, target_type.type_symbol, this);
			// check compatibility of generic type arguments
			var base_type_args = base_type.get_type_arguments();
			if (base_type_args.size == target_type_args.size) {
				for (int i = 0; i < base_type_args.size; i++) {
					// mutable generic types require type argument equality,
					// not just one way compatibility
					// as we do not currently have immutable generic container types,
					// the additional check would be very inconvenient, so we
					// skip the additional check for now
					if (!base_type_args[i].compatible (target_type_args[i])) {
						return false;
					}
				}
			}
			return true;
		}

		if (type_symbol is Struct && target_type.type_symbol is Struct) {
			unowned Struct expr_struct = (Struct) type_symbol;
			unowned Struct expect_struct = (Struct) target_type.type_symbol;

			/* integer types may be implicitly cast to floating point types */
			if (expr_struct.is_integer_type () && expect_struct.is_floating_type ()) {
				return true;
			}

			if ((expr_struct.is_integer_type () && expect_struct.is_integer_type ()) ||
			    (expr_struct.is_floating_type () && expect_struct.is_floating_type ())) {
				if (expr_struct.rank <= expect_struct.rank) {
					return true;
				}
			}

			if (expr_struct.is_boolean_type () && expect_struct.is_boolean_type ()) {
				return true;
			}

			// Allow compatibility of struct subtypes in both ways
			if (expect_struct.is_subtype_of (expr_struct)) {
				return true;
			}
		}

		return false;
	}

	/**
	 * Returns whether instances of this type are invokable.
	 *
	 * @return true if invokable, false otherwise
	 */
	public virtual bool is_invokable () {
		return false;
	}

	/**
	 * Returns the return type of this invokable.
	 *
	 * @return return type
	 */
	public virtual unowned DataType? get_return_type () {
		return null;
	}

	/**
	 * Returns the list of invocation parameters.
	 *
	 * @return parameter list
	 */
	public virtual unowned List<Parameter>? get_parameters () {
		return null;
	}

	public virtual bool is_reference_type_or_type_parameter () {
		return (type_symbol != null &&
		        type_symbol.is_reference_type ()) ||
		       this is GenericType;
	}

	// check whether this type is at least as accessible as the specified symbol
	public virtual bool is_accessible (Symbol sym) {
		foreach (var type_arg in get_type_arguments ()) {
			if (!type_arg.is_accessible (sym)) {
				return false;
			}
		}
		if (type_symbol != null) {
			return type_symbol.is_accessible (sym);
		}
		return true;
	}

	public virtual Symbol? get_member (string member_name) {
		Symbol? member = null;
		if (context_symbol != null) {
			member = SemanticAnalyzer.symbol_lookup_inherited (context_symbol, member_name);
		}
		if (member == null && type_symbol != null) {
			member = SemanticAnalyzer.symbol_lookup_inherited (type_symbol, member_name);
		}
		return member;
	}

	public virtual Symbol? get_pointer_member (string member_name) {
		return null;
	}

	/**
	 * Checks whether this data type references a real struct. A real struct
	 * is a struct which is not a simple (fundamental) type.
	 */
	public virtual bool is_real_struct_type () {
		unowned Struct? s = type_symbol as Struct;
		if (s != null && !s.is_simple_type ()) {
			return true;
		}
		return false;
	}

	public bool is_real_non_null_struct_type () {
		return is_real_struct_type () && !nullable;
	}

	public bool is_non_null_simple_type () {
		unowned Struct? s = type_symbol as Struct;
		if (s != null && s.is_simple_type ()) {
			return !nullable;
		}
		if (type_symbol is Enum) {
			return !nullable;
		}
		return false;
	}

	/**
	 * Returns whether the value needs to be disposed, i.e. whether
	 * allocated memory or other resources need to be released when
	 * the value is no longer needed.
	 */
	public virtual bool is_disposable () {
		if (!value_owned) {
			return false;
		}

		if (is_reference_type_or_type_parameter ()) {
			return true;
		}
		return false;
	}

	public virtual DataType get_actual_type (DataType? derived_instance_type, List<DataType>? method_type_arguments, CodeNode? node_reference) {
		DataType result = this.copy ();

		if (derived_instance_type == null && method_type_arguments == null) {
			return result;
		}

		if (result.type_argument_list != null) {
			// recursely get actual types for type arguments
			for (int i = 0; i < result.type_argument_list.size; i++) {
				result.type_argument_list[i] = result.type_argument_list[i].get_actual_type (derived_instance_type, method_type_arguments, node_reference);
			}
		}

		return result;
	}

	public bool is_generic () {
		if (this is GenericType) {
			return true;
		}

		if (!has_type_arguments ()) {
			return false;
		}
		foreach (var type_arg in type_argument_list) {
			if (type_arg.is_generic ()) {
				return true;
			}
		}
		return false;
	}

	public void replace_type_parameter (TypeParameter old_type_param, TypeParameter new_type_param) {
		if (this is GenericType) {
			if (symbol == old_type_param) {
				symbol = new_type_param;
			}
			return;
		}
		if (!has_type_arguments ()) {
			return;
		}
		foreach (var type_arg in type_argument_list) {
			type_arg.replace_type_parameter (old_type_param, new_type_param);
		}
	}

	/**
	 * Search for the type parameter in this formal type and match it in
	 * value_type.
	 */
	public virtual DataType? infer_type_argument (TypeParameter type_param, DataType value_type) {
		var value_type_arg_it = value_type.get_type_arguments ().iterator ();
		foreach (var formal_type_arg in this.get_type_arguments ()) {
			if (value_type_arg_it.next ()) {
				var inferred_type = formal_type_arg.infer_type_argument (type_param, value_type_arg_it.get ());
				if (inferred_type != null) {
					return inferred_type;
				}
			}
		}

		return null;
	}

	/**
	 * Returns a stringified representation used for detailed error output
	 *
	 * @param override_name used as name if given
	 * @return stringified representation
	 */
	public virtual string to_prototype_string (string? override_name = null) {
		return "%s%s".printf (is_weak () ? "unowned " : "", to_qualified_string ());
	}

	public bool is_weak () {
		if (this.value_owned) {
			return false;
		} else if (this is VoidType || this is PointerType) {
			return false;
		} else if (this is ValueType) {
			if (this.nullable) {
				// nullable structs are heap allocated
				return true;
			}

			// TODO return true for structs with destroy
			return false;
		}

		return true;
	}

	public string? get_type_signature (Symbol? symbol = null) {
		if (symbol != null) {
			string sig = symbol.get_attribute_string ("DBus", "signature");
			if (sig != null) {
				// allow overriding signature in attribute, used for raw GVariants
				return sig;
			}
		}

		unowned ArrayType? array_type = this as ArrayType;

		if (array_type != null) {
			string element_type_signature = array_type.element_type.get_type_signature ();

			if (element_type_signature == null) {
				return null;
			}

			return string.nfill (array_type.rank, 'a') + element_type_signature;
		} else if (type_symbol is Enum && type_symbol.get_attribute_bool ("DBus", "use_string_marshalling")) {
			return "s";
		} else if (type_symbol != null) {
			string sig = type_symbol.get_attribute_string ("CCode", "type_signature");

			unowned Struct? st = type_symbol as Struct;
			unowned Enum? en = type_symbol as Enum;
			if (sig == null && st != null) {
				var str = new StringBuilder ();
				str.append_c ('(');
				foreach (Field f in st.get_fields ()) {
					if (f.binding == MemberBinding.INSTANCE) {
						var s = f.variable_type.get_type_signature (f);
						if (s != null) {
							str.append (s);
						} else {
							return null;
						}
					}
				}
				str.append_c (')');
				sig = str.str;
			} else if (sig == null && en != null) {
				if (en.is_flags) {
					return "u";
				} else {
					return "i";
				}
			}

			var type_args = get_type_arguments ();
			if (sig != null && "%s" in sig && type_args.size > 0) {
				string element_sig = "";
				foreach (DataType type_arg in type_args) {
					var s = type_arg.get_type_signature ();
					if (s != null) {
						element_sig += s;
					}
				}

				sig = sig.replace ("%s", element_sig);
			}

			if (sig == null &&
			    (type_symbol.get_full_name () == "GLib.UnixInputStream" ||
			     type_symbol.get_full_name () == "GLib.UnixOutputStream" ||
			     type_symbol.get_full_name () == "GLib.Socket")) {
				return "h";
			}

			return sig;
		} else {
			return null;
		}
	}

	/**
	 * Returns whether the given amount of type-argument matches the symbol's count of type-parameters
	 *
	 * @param context a CodeContext
	 * @param allow_none whether no type-argments are allowed
	 * @return true if successful
	 */
	public bool check_type_arguments (CodeContext context, bool allow_none = false) {
		int n_type_args = get_type_arguments ().size;
		int expected_n_type_args = 0;

		if (type_symbol is GenericSymbol) {
			expected_n_type_args = ((GenericSymbol) type_symbol).get_type_parameters ().size;
		} else if (n_type_args > 0) {
			Report.error (source_reference, "`%s' does not support type arguments", type_symbol.get_full_name ());
			error = true;
			return false;
		} else {
			// nothing to do here
			return true;
		}

		if ((!allow_none || n_type_args > 0) && n_type_args < expected_n_type_args) {
			error = true;
			Report.error (source_reference, "too few type arguments for `%s'", type_symbol.to_string ());
			return false;
		} else if ((!allow_none || n_type_args > 0) && n_type_args > expected_n_type_args) {
			error = true;
			Report.error (source_reference, "too many type arguments for `%s'", type_symbol.to_string ());
			return false;
		}

		foreach (DataType type in get_type_arguments ()) {
			if (!type.check (context)) {
				return false;
			}
		}

		return true;
	}
}