/*
 * Copyright (C)2005-2019 Haxe Foundation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

package haxe;

import haxe.ds.List;

/**
	The Serializer class can be used to encode values and objects into a `String`,
	from which the `Unserializer` class can recreate the original representation.

	This class can be used in two ways:

	- create a `new Serializer()` instance, call its `serialize()` method with
		any argument and finally retrieve the String representation from
		`toString()`
	- call `Serializer.run()` to obtain the serialized representation of a
		single argument

	Serialization is guaranteed to work for all haxe-defined classes, but may
	or may not work for instances of external/native classes.

	The specification of the serialization format can be found here:
	<https://haxe.org/manual/std-serialization-format.html>
**/
class Serializer {
	/**
		Enables object caching during serialization to handle circular references and
		repeated objects.

		Set `USE_CACHE` to `true` if the values you are serializing may contain
		circular references or repeated objects. This prevents infinite loops and
		ensures that shared references are preserved in the serialized output.

		Enabling this option may also reduce the size of the resulting serialized
		string, but can have a minor performance impact.

		This is a global default. You can override it per instance using the
		`useCache` field on a `Serializer`.
	 */
	public static var USE_CACHE = false;

	/**
		Serializes enum values using constructor indices instead of names.

		When `USE_ENUM_INDEX` is set to `true`, enum constructors are serialized by
		their numeric index. This can reduce the size of the serialized data,
		especially for enums with long or frequently used constructor names.

		However, using indices makes serialized data more fragile for long-term
		storage. If enum definitions change (e.g., by adding or removing constructors),
		the indices may no longer match the intended constructors.

		This is a global default. You can override it per instance using the
		`useEnumIndex` field on a `Serializer`.
	 */
	public static var USE_ENUM_INDEX = false;

	static var BASE64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789%:";
	static var BASE64_CODES = null;

	var buf:StringBuf;
	var cache:Array<Dynamic>;
	var shash:haxe.ds.StringMap<Int>;
	var scount:Int;

	/**
		Determines whether this `Serializer` instance uses object caching.

		When enabled, repeated references to the same object are serialized using references
		instead of duplicating data, reducing output size and preserving object identity.

		See `USE_CACHE` for a complete description.
	 */
	public var useCache:Bool;

	/**
		Determines whether this `Serializer` instance serializes enum values using their index
		instead of their constructor name.

		Using indexes can reduce the size of the serialized data but may be less readable and
		more fragile if enum definitions change.

		See `USE_ENUM_INDEX` for a complete description.
	 */
	public var useEnumIndex:Bool;

	/**
		Creates a new Serializer instance.

		Subsequent calls to `this.serialize` will append values to the
		internal buffer of this String. Once complete, the contents can be
		retrieved through a call to `this.toString`.

		Each `Serializer` instance maintains its own cache if `this.useCache` is
		`true`.
	**/
	public function new() {
		buf = new StringBuf();
		cache = new Array();
		useCache = USE_CACHE;
		useEnumIndex = USE_ENUM_INDEX;
		shash = new haxe.ds.StringMap();
		scount = 0;
	}

	/**
		Resets the internal state of the Serializer, allowing it to be reused.

		This does not affect the `useCache` or `useEnumIndex` properties;
		their values will remain unchanged after calling this method.
	**/
	public function reset() {
		buf.clear();
		cache.resize(0);
		shash.clear();
		scount = 0;
	}

	/**
		Return the String representation of `this` Serializer.

		The exact format specification can be found here:
		https://haxe.org/manual/serialization/format
	**/
	public function toString() {
		return buf.toString();
	}

	/* prefixes :
		a : array
		b : hash
		c : class
		d : Float
		e : reserved (float exp)
		f : false
		g : object end
		h : array/list/hash end
		i : Int
		j : enum (by index)
		k : NaN
		l : list
		m : -Inf
		n : null
		o : object
		p : +Inf
		q : haxe.ds.IntMap
		r : reference
		s : bytes (base64)
		t : true
		u : array nulls
		v : date
		w : enum
		x : exception
		y : urlencoded string
		z : zero
		A : Class<Dynamic>
		B : Enum<Dynamic>
		M : haxe.ds.ObjectMap
		C : custom
	 */
	function serializeString(s:String) {
		var x = shash.get(s);
		if (x != null) {
			buf.add("R");
			buf.add(x);
			return;
		}
		shash.set(s, scount++);
		buf.add("y");
		s = StringTools.urlEncode(s);
		buf.add(s.length);
		buf.add(":");
		buf.add(s);
	}

	function serializeRef(v:Dynamic) {
		#if js
		var vt = js.Syntax.typeof(v);
		#end
		for (i in 0...cache.length) {
			#if js
			var ci = cache[i];
			if (js.Syntax.typeof(ci) == vt && ci == v) {
			#else
			if (cache[i] == v) {
			#end
				buf.add("r");
				buf.add(i);
				return true;
			}
		}
		cache.push(v);
		return false;
	}

	#if flash
	// only the instance variables

	function serializeClassFields(v:Dynamic, c:Dynamic) {
		var xml:flash.xml.XML = untyped __global__["flash.utils.describeType"](c);
		var vars = xml.factory[0].child("variable");
		for (i in 0...vars.length()) {
			var f = vars[i].attribute("name").toString();
			if (!v.hasOwnProperty(f))
				continue;
			serializeString(f);
			serialize(Reflect.field(v, f));
		}
		buf.add("g");
	}
	#end

	function serializeFields(v:{}) {
		for (f in Reflect.fields(v)) {
			serializeString(f);
			serialize(Reflect.field(v, f));
		}
		buf.add("g");
	}

	/**
		Serializes `v`.
	
		All haxe-defined values and objects with the exception of functions can
		be serialized. Serialization of external/native objects is not
		guaranteed to work. This is also true for classes extending external/native
		classes. On some targets, this might include exceptions, too.
	
		The values of `this.useCache` and `this.useEnumIndex` may affect
		serialization output.
	**/
	public function serialize(v:Dynamic) {
		switch (Type.typeof(v)) {
			case TNull:
				buf.add("n");
			case TInt:
				var v:Int = v;
				if (v == 0) {
					buf.add("z");
					return;
				}
				buf.add("i");
				buf.add(v);
			case TFloat:
				var v:Float = v;
				if (Math.isNaN(v))
					buf.add("k");
				else if (!Math.isFinite(v))
					buf.add(if (v < 0) "m" else "p");
				else {
					buf.add("d");
					buf.add(v);
				}
			case TBool:
				buf.add(if (v) "t" else "f");
			case TClass(String):
				serializeString(v);
			case TClass(_) if (useCache && serializeRef(v)):
			case TClass(Array):
				var ucount = 0;
				buf.add("a");
				var v:Array<Dynamic> = v;
				var l = v.length;
				for (i in 0...l) {
					if (v[i] == null)
						ucount++;
					else {
						if (ucount > 0) {
							if (ucount == 1)
								buf.add("n");
							else {
								buf.add("u");
								buf.add(ucount);
							}
							ucount = 0;
						}
						serialize(v[i]);
					}
				}
				if (ucount > 0) {
					if (ucount == 1)
						buf.add("n");
					else {
						buf.add("u");
						buf.add(ucount);
					}
				}
				buf.add("h");
			case TClass(haxe.ds.List):
				buf.add("l");
				var v:List<Dynamic> = v;
				for (i in v)
					serialize(i);
				buf.add("h");
			case TClass(haxe.ds.StringMap):
				buf.add("b");
				var v:haxe.ds.StringMap<Dynamic> = v;
				for (k in v.keys()) {
					serializeString(k);
					serialize(v.get(k));
				}
				buf.add("h");
			case TClass(haxe.ds.IntMap):
				buf.add("q");
				var v:haxe.ds.IntMap<Dynamic> = v;
				for (k in v.keys()) {
					buf.add(":");
					buf.add(k);
					serialize(v.get(k));
				}
				buf.add("h");
			case TClass(haxe.ds.ObjectMap):
				buf.add("M");
				var v:haxe.ds.ObjectMap<Dynamic, Dynamic> = v;
				for (k in v.keys()) {
					#if (js || neko)
					var id = Reflect.field(k, "__id__");
					Reflect.deleteField(k, "__id__");
					serialize(k);
					Reflect.setField(k, "__id__", id);
					#else
					serialize(k);
					#end
					serialize(v.get(k));
				}
				buf.add("h");
			case TClass(Date):
				var d:Date = v;
				buf.add("v");
				buf.add(d.getTime());
			case TClass(haxe.io.Bytes):
				var v:haxe.io.Bytes = v;
				#if neko
				var chars = new String(base_encode(v.getData(), untyped BASE64.__s));
				buf.add("s");
				buf.add(chars.length);
				buf.add(":");
				buf.add(chars);
				#elseif php
				var chars = new String(php.Global.base64_encode(v.getData()));
				chars = php.Global.strtr(chars, '+/', '%:');
				buf.add("s");
				buf.add(chars.length);
				buf.add(":");
				buf.add(chars);
				#else
				buf.add("s");
				buf.add(Math.ceil((v.length * 8) / 6));
				buf.add(":");

				var i = 0;
				var max = v.length - 2;
				var b64 = BASE64_CODES;
				if (b64 == null) {
					b64 = new haxe.ds.Vector(BASE64.length);
					for (i in 0...BASE64.length)
						b64[i] = BASE64.charCodeAt(i);
					BASE64_CODES = b64;
				}
				while (i < max) {
					var b1 = v.get(i++);
					var b2 = v.get(i++);
					var b3 = v.get(i++);

					buf.addChar(b64[b1 >> 2]);
					buf.addChar(b64[((b1 << 4) | (b2 >> 4)) & 63]);
					buf.addChar(b64[((b2 << 2) | (b3 >> 6)) & 63]);
					buf.addChar(b64[b3 & 63]);
				}
				if (i == max) {
					var b1 = v.get(i++);
					var b2 = v.get(i++);
					buf.addChar(b64[b1 >> 2]);
					buf.addChar(b64[((b1 << 4) | (b2 >> 4)) & 63]);
					buf.addChar(b64[(b2 << 2) & 63]);
				} else if (i == max + 1) {
					var b1 = v.get(i++);
					buf.addChar(b64[b1 >> 2]);
					buf.addChar(b64[(b1 << 4) & 63]);
				}
				#end
			case TClass(c):
				if (
					#if flash
					try
						v.hxSerialize != null
					catch (e:Dynamic)
						false
					#elseif (java || python)
					Reflect.hasField(v, "hxSerialize")
					#elseif php
					php.Global.method_exists(v, 'hxSerialize')
					#else
					v.hxSerialize != null
					#end) {
					buf.add("C");
					serializeString(Type.getClassName(c));
					v.hxSerialize(this);
					buf.add("g");
				} else {
					buf.add("c");
					serializeString(Type.getClassName(c));
					#if flash
					serializeClassFields(v, c);
					#else
					serializeFields(v);
					#end
				}
			case TObject:
				if (Std.isOfType(v, Class)) {
					var className = Type.getClassName(v);
					#if (flash || cpp)
					// Currently, Enum and Class are the same for flash and cpp.
					//  use resolveEnum to test if it is actually an enum
					if (Type.resolveEnum(className) != null)
						buf.add("B")
					else
					#end
					buf.add("A");
					serializeString(className);
				} else if (Std.isOfType(v, Enum)) {
					buf.add("B");
					serializeString(Type.getEnumName(v));
				} else {
					if (useCache && serializeRef(v))
						return;
					buf.add("o");
					serializeFields(v);
				}
			case TEnum(e):
				if (useCache) {
					if (serializeRef(v))
						return;
					cache.pop();
				}
				buf.add(useEnumIndex ? "j" : "w");
				serializeString(Type.getEnumName(e));
				#if neko
				if (useEnumIndex) {
					buf.add(":");
					buf.add(v.index);
				} else
					serializeString(new String(v.tag));
				buf.add(":");
				if (v.args == null)
					buf.add(0);
				else {
					var l:Int = untyped __dollar__asize(v.args);
					buf.add(l);
					for (i in 0...l)
						serialize(v.args[i]);
				}
				#elseif flash
				if (useEnumIndex) {
					buf.add(":");
					var i:Int = v.index;
					buf.add(i);
				} else
					serializeString(v.tag);
				buf.add(":");
				var pl:Array<Dynamic> = v.params;
				if (pl == null)
					buf.add(0);
				else {
					buf.add(pl.length);
					for (p in pl)
						serialize(p);
				}
				#elseif cpp
				var enumBase:cpp.EnumBase = v;
				if (useEnumIndex) {
					buf.add(":");
					buf.add(enumBase.getIndex());
				} else
					serializeString(enumBase.getTag());
				buf.add(":");
				var len = enumBase.getParamCount();
				buf.add(len);
				for (p in 0...len)
					serialize(enumBase.getParamI(p));
				#elseif php
				if (useEnumIndex) {
					buf.add(":");
					buf.add(v.index);
				} else
					serializeString(v.tag);
				buf.add(":");
				var l:Int = php.Syntax.code("count({0})", v.params);
				if (l == 0 || v.params == null)
					buf.add(0);
				else {
					buf.add(l);
					for (i in 0...l) {
						#if php
						serialize(v.params[i]);
						#end
					}
				}
				#elseif (java || python || hl || eval)
				if (useEnumIndex) {
					buf.add(":");
					buf.add(Type.enumIndex(v));
				} else
					serializeString(Type.enumConstructor(v));
				buf.add(":");
				var arr:Array<Dynamic> = Type.enumParameters(v);
				if (arr != null) {
					buf.add(arr.length);
					for (v in arr)
						serialize(v);
				} else {
					buf.add("0");
				}
				#elseif (js && !js_enums_as_arrays)
				if (useEnumIndex) {
					buf.add(":");
					buf.add(v._hx_index);
				} else
					serializeString(Type.enumConstructor(v));
				buf.add(":");
				var params = Type.enumParameters(v);
				buf.add(params.length);
				for (p in params)
					serialize(p);
				#else
				if (useEnumIndex) {
					buf.add(":");
					buf.add(v[1]);
				} else
					serializeString(v[0]);
				buf.add(":");
				var l = __getField(v, "length");
				buf.add(l - 2);
				for (i in 2...l)
					serialize(v[i]);
				#end
				if (useCache)
					cache.push(v);
			case TFunction:
				throw "Cannot serialize function";
			default:
				#if neko
				if (untyped (__i32__kind != null && __dollar__iskind(v, __i32__kind))) {
					buf.add("i");
					buf.add(v);
					return;
				}
				#end
				throw "Cannot serialize " + Std.string(v);
		}
	}

	extern inline function __getField(o:Dynamic, f:String):Dynamic
		return o[cast f];

	public function serializeException(e:Dynamic) {
		buf.add("x");
		#if flash
		if (untyped __is__(e, __global__["Error"])) {
			var e:flash.errors.Error = e;
			var s = e.getStackTrace();
			if (s == null)
				serialize(e.message);
			else
				serialize(s);
			return;
		}
		#end
		serialize(e);
	}

	/**
		Serializes `v` and returns the String representation.
	
		This is a convenience function for creating a new instance of
		Serializer, serialize `v` into it and obtain the result through a call
		to `toString()`.
	**/
	public static function run(v:Dynamic) {
		var s = new Serializer();
		s.serialize(v);
		return s.toString();
	}

	#if neko
	static var base_encode = neko.Lib.load("std", "base_encode", 2);
	#end
}
