/*
 * 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.
 */
@:coreApi
class String {
	var bytes:hl.Bytes;

	public var length(default, null):Int;

	public function new(string:String):Void {
		bytes = string.bytes;
		length = string.length;
	}

	public function toUpperCase():String {
		return __alloc__(@:privateAccess bytes.ucs2Upper(0, length), length);
	}

	public function toLowerCase():String {
		return __alloc__(@:privateAccess bytes.ucs2Lower(0, length), length);
	}

	public function charAt(index:Int):String {
		if ((index : UInt) >= (length : UInt))
			return "";
		return __char__(bytes.getUI16(index << 1));
	}

	public function charCodeAt(index:Int):Null<Int> {
		var idx:UInt = index;
		if (idx >= (length : UInt))
			return null;
		return bytes.getUI16(index << 1);
	}

	inline function findChar(start:Int, len:Int, src:hl.Bytes, srcLen:Int):Int {
		var p = 0;
		while (true) {
			p = bytes.find(start, len - start, src, 0, srcLen);
			if (p < 0 || p & 1 == 0)
				break;
			start = p + 1;
		}
		return p;
	}

	public function indexOf(str:String, ?startIndex:Int):Int {
		var startByte = 0;
		if (startIndex != null && startIndex > 0) {
			if (startIndex >= length)
				return str == '' ? length : -1;
			startByte = startIndex << 1;
		}
		var p = findChar(startByte, length << 1, str.bytes, str.length << 1);
		if (p > 0)
			p >>= 1;
		return p;
	}

	public function lastIndexOf(str:String, ?startIndex:Int):Int {
		var max = this.length;
		if (startIndex != null) {
			max = startIndex + str.length;
			if (max < 0)
				max = 0;
			if (max > this.length)
				max = this.length;
		}
		var pos = max - str.length;
		var slen = str.length << 1;
		while (pos >= 0) {
			if (bytes.compare(pos << 1, str.bytes, 0, slen) == 0)
				return pos;
			pos--;
		}
		return -1;
	}

	public function split(delimiter:String):Array<String> {
		var out = [];
		if (length == 0) {
			out.push("");
			return out;
		}
		if (delimiter.length == 0) {
			for (i in 0...length)
				out.push(substr(i, 1));
			return out;
		}
		var pos = 0;
		var dlen = delimiter.length;
		while (true) {
			var p = findChar(pos << 1, length << 1, delimiter.bytes, dlen << 1);
			if (p < 0) {
				out.push(substr(pos, length - pos));
				break;
			}
			p >>= 1;
			out.push(substr(pos, p - pos));
			pos = p + dlen;
		}
		return out;
	}

	public function substr(pos:Int, ?len:Int):String@:privateAccess {
		var sl = length;
		var len:Int = if (len == null) sl else len;
		if (len == 0)
			return "";
		if (pos != 0 && len < 0)
			return "";
		if (pos < 0) {
			pos = sl + pos;
			if (pos < 0)
				pos = 0;
		} else if (len < 0) {
			len = sl + len - pos;
			if (len < 0)
				return "";
		}
		if (((pos + len) : UInt) > (sl : UInt))
			len = sl - pos;
		if (pos < 0 || len <= 0)
			return "";
		if( len == 1 )
			return __char__(bytes.getUI16(pos << 1));
		var b = new hl.Bytes((len + 1) << 1);
		b.blit(0, bytes, pos << 1, len << 1);
		b.setUI16(len << 1, 0);
		return __alloc__(b, len);
	}

	public function substring(startIndex:Int, ?endIndex:Int):String {
		var end:Int;
		if (endIndex == null)
			end = length;
		else {
			end = endIndex;
			if (end < 0)
				end = 0;
			else if (end > length)
				end = length;
		}
		if (startIndex < 0)
			startIndex = 0;
		else if (startIndex > length)
			startIndex = length;
		if (startIndex > end) {
			var tmp = startIndex;
			startIndex = end;
			end = tmp;
		}
		return substr(startIndex, end - startIndex);
	}

	public function toString():String {
		return this;
	}

	public static function fromCharCode(code:Int):String {
		if (code >= 0 && code < 0x10000) {
			if (code >= 0xD800 && code <= 0xDFFF)
				throw "Invalid unicode char " + code;
			return __char__(code);
		} else if (code < 0x110000) {
			var b = new hl.Bytes(6);
			code -= 0x10000;
			b.setUI16(0, (code >> 10) + 0xD800);
			b.setUI16(2, (code & 1023) + 0xDC00);
			b.setUI16(4, 0);
			return __alloc__(b, 2); // UTF16 encoding but UCS2 API (same as JS)
		} else
			throw "Invalid unicode char " + code;
	}

	function toUtf8():hl.Bytes {
		return bytes.utf16ToUtf8(0, null);
	}

	@:keep function __string():hl.Bytes {
		return bytes;
	}

	@:keep function __compare(v:Dynamic):Int {
		var s = Std.downcast(v, String);
		if (s == null)
			return hl.Api.comparePointer(this, v);
		#if (hl_ver >= version("1.10.0"))
		var v = bytes.compare16(s.bytes, length < s.length ? length : s.length);
		#else
		var v = bytes.compare(0, s.bytes, 0, (length < s.length ? length : s.length) << 1);
		#end
		return v == 0 ? length - s.length : v;
	}

	@:keep static inline function __alloc__(b:hl.Bytes, length:Int):String {
		var s:String = untyped $new(String);
		s.bytes = b;
		s.length = length;
		return s;
	}

	@:keep static function call_toString(v:Dynamic):hl.Bytes {
		var s:String = v.toString();
		return s.bytes;
	}

	inline static function fromUCS2(b:hl.Bytes):String {
		var s:String = untyped $new(String);
		s.bytes = b;
		s.length = @:privateAccess b.ucs2Length(0);
		return s;
	}

	@:keep static function fromUTF8(b:hl.Bytes):String {
		var outLen = 0;
		var b2 = @:privateAccess b.utf8ToUtf16(0, outLen);
		if( outLen == 2 ) {
			var c = b2.getUI16(0);
			if( c < 256 ) return __char__(c);
		}
		return __alloc__(b2, outLen >> 1);
	}

	static var CHARS = new hl.NativeArray<String>(256);
	@:keep static function __char__(code:Int):String {
		if( code < 256 ) {
			var s = CHARS[code];
			if( s == null ) {
				var b = new hl.Bytes(4);
				b.setUI16(0, code);
				b.setUI16(2, 0);
				s = __alloc__(b, 1);
				CHARS[code] = s;
			}
			return s;
		}
		var b = new hl.Bytes(4);
		b.setUI16(0, code);
		b.setUI16(2, 0);
		return __alloc__(b, 1);
	}
	
	@:keep static function __add__(a:String, b:String):String {
		if (a == null)
			a = "null";
		if (b == null)
			b = "null";
		if( a.length == 0 )
			return b;
		if( b.length == 0 )
			return a;
		var asize = a.length << 1, bsize = b.length << 1, tot = asize + bsize;
		var bytes = new hl.Bytes(tot + 2);
		bytes.blit(0, a.bytes, 0, asize);
		bytes.blit(asize, b.bytes, 0, bsize);
		bytes.setUI16(tot, 0);
		return __alloc__(bytes, tot >> 1);
	}
}
