import { Unpackr, mult10, C1Type, typedArrays, addExtension as unpackAddExtension } from './unpack.js';
let textEncoder;
try {
	textEncoder = new TextEncoder();
} catch (error) {}
let extensions, extensionClasses;
const hasNodeBuffer = typeof Buffer !== 'undefined';
const ByteArrayAllocate = hasNodeBuffer ?
	function(length) { return Buffer.allocUnsafeSlow(length); } : Uint8Array;
const ByteArray = hasNodeBuffer ? Buffer : Uint8Array;
const MAX_BUFFER_SIZE = hasNodeBuffer ? 0x100000000 : 0x7fd00000;
let target, keysTarget;
let targetView;
let position = 0;
let safeEnd;
let bundledStrings = null;
const MAX_BUNDLE_SIZE = 0x5500; // maximum characters such that the encoded bytes fits in 16 bits.
const hasNonLatin = /[\u0080-\uFFFF]/;
export const RECORD_SYMBOL = Symbol('record-id');
export class Packr extends Unpackr {
	constructor(options) {
		super(options);
		this.offset = 0;
		let typeBuffer;
		let start;
		let hasSharedUpdate;
		let structures;
		let referenceMap;
		let encodeUtf8 = ByteArray.prototype.utf8Write ? function(string, position) {
			return target.utf8Write(string, position, target.byteLength - position);
		} : (textEncoder && textEncoder.encodeInto) ?
			function(string, position) {
				return textEncoder.encodeInto(string, target.subarray(position)).written;
			} : false;

		let packr = this;
		if (!options)
			options = {};
		let isSequential = options && options.sequential;
		let hasSharedStructures = options.structures || options.saveStructures;
		let maxSharedStructures = options.maxSharedStructures;
		if (maxSharedStructures == null)
			maxSharedStructures = hasSharedStructures ? 32 : 0;
		if (maxSharedStructures > 8160)
			throw new Error('Maximum maxSharedStructure is 8160');
		if (options.structuredClone && options.moreTypes == undefined) {
			this.moreTypes = true;
		}
		let maxOwnStructures = options.maxOwnStructures;
		if (maxOwnStructures == null)
			maxOwnStructures = hasSharedStructures ? 32 : 64;
		if (!this.structures && options.useRecords != false)
			this.structures = [];
		// two byte record ids for shared structures
		let useTwoByteRecords = maxSharedStructures > 32 || (maxOwnStructures + maxSharedStructures > 64);
		let sharedLimitId = maxSharedStructures + 0x40;
		let maxStructureId = maxSharedStructures + maxOwnStructures + 0x40;
		if (maxStructureId > 8256) {
			throw new Error('Maximum maxSharedStructure + maxOwnStructure is 8192');
		}
		let recordIdsToRemove = [];
		let transitionsCount = 0;
		let serializationsSinceTransitionRebuild = 0;

		this.pack = this.encode = function(value, encodeOptions) {
			if (!target) {
				target = new ByteArrayAllocate(8192);
				targetView = target.dataView || (target.dataView = new DataView(target.buffer, 0, 8192));
				position = 0;
			}
			safeEnd = target.length - 10;
			if (safeEnd - position < 0x800) {
				// don't start too close to the end,
				target = new ByteArrayAllocate(target.length);
				targetView = target.dataView || (target.dataView = new DataView(target.buffer, 0, target.length));
				safeEnd = target.length - 10;
				position = 0;
			} else
				position = (position + 7) & 0x7ffffff8; // Word align to make any future copying of this buffer faster
			start = position;
			if (encodeOptions & RESERVE_START_SPACE) position += (encodeOptions & 0xff);
			referenceMap = packr.structuredClone ? new Map() : null;
			if (packr.bundleStrings && typeof value !== 'string') {
				bundledStrings = [];
				bundledStrings.size = Infinity; // force a new bundle start on first string
			} else
				bundledStrings = null;
			structures = packr.structures;
			if (structures) {
				if (structures.uninitialized)
					structures = packr._mergeStructures(packr.getStructures());
				let sharedLength = structures.sharedLength || 0;
				if (sharedLength > maxSharedStructures) {
					//if (maxSharedStructures <= 32 && structures.sharedLength > 32) // TODO: could support this, but would need to update the limit ids
					throw new Error('Shared structures is larger than maximum shared structures, try increasing maxSharedStructures to ' + structures.sharedLength);
				}
				if (!structures.transitions) {
					// rebuild our structure transitions
					structures.transitions = Object.create(null);
					for (let i = 0; i < sharedLength; i++) {
						let keys = structures[i];
						if (!keys)
							continue;
						let nextTransition, transition = structures.transitions;
						for (let j = 0, l = keys.length; j < l; j++) {
							let key = keys[j];
							nextTransition = transition[key];
							if (!nextTransition) {
								nextTransition = transition[key] = Object.create(null);
							}
							transition = nextTransition;
						}
						transition[RECORD_SYMBOL] = i + 0x40;
					}
					this.lastNamedStructuresLength = sharedLength;
				}
				if (!isSequential) {
					structures.nextId = sharedLength + 0x40;
				}
			}
			if (hasSharedUpdate)
				hasSharedUpdate = false;
			let encodingError;
			try {
				if (packr._writeStruct && value && typeof value === 'object') {
					if (value.constructor === Object) writeStruct(value); // simple object
					else if (value.constructor !== Map && !Array.isArray(value) && !extensionClasses.some(extClass => value instanceof extClass)) {
						// allow user classes, if they don't need special handling (but do use toJSON if available)
						writeStruct(value.toJSON ? value.toJSON() : value);
					} else pack(value);
				} else
					pack(value);
				let lastBundle = bundledStrings;
				if (bundledStrings)
					writeBundles(start, pack, 0);
				if (referenceMap && referenceMap.idsToInsert) {
					let idsToInsert = referenceMap.idsToInsert.sort((a, b) => a.offset > b.offset ? 1 : -1);
					let i = idsToInsert.length;
					let incrementPosition = -1;
					while (lastBundle && i > 0) {
						let insertionPoint = idsToInsert[--i].offset + start;
						if (insertionPoint < (lastBundle.stringsPosition + start) && incrementPosition === -1)
							incrementPosition = 0;
						if (insertionPoint > (lastBundle.position + start)) {
							if (incrementPosition >= 0)
								incrementPosition += 6;
						} else {
							if (incrementPosition >= 0) {
								// update the bundle reference now
								targetView.setUint32(lastBundle.position + start,
									targetView.getUint32(lastBundle.position + start) + incrementPosition);
								incrementPosition = -1; // reset
							}
							lastBundle = lastBundle.previous;
							i++;
						}
					}
					if (incrementPosition >= 0 && lastBundle) {
						// update the bundle reference now
						targetView.setUint32(lastBundle.position + start,
							targetView.getUint32(lastBundle.position + start) + incrementPosition);
					}
					position += idsToInsert.length * 6;
					if (position > safeEnd)
						makeRoom(position);
					packr.offset = position;
					let serialized = insertIds(target.subarray(start, position), idsToInsert);
					referenceMap = null;
					return serialized;
				}
				packr.offset = position; // update the offset so next serialization doesn't write over our buffer, but can continue writing to same buffer sequentially
				if (encodeOptions & REUSE_BUFFER_MODE) {
					target.start = start;
					target.end = position;
					return target;
				}
				return target.subarray(start, position); // position can change if we call pack again in saveStructures, so we get the buffer now
			} catch(error) {
				encodingError = error;
				throw error;
			} finally {
				if (structures) {
					resetStructures();
					if (hasSharedUpdate && packr.saveStructures) {
						let sharedLength = structures.sharedLength || 0;
						// we can't rely on start/end with REUSE_BUFFER_MODE since they will (probably) change when we save
						let returnBuffer = target.subarray(start, position);
						let newSharedData = (packr._prepareStructures || prepareStructures)(structures, packr);
						if (!encodingError) { // TODO: If there is an encoding error, should make the structures as uninitialized so they get rebuilt next time
							if (packr.saveStructures(newSharedData, newSharedData.isCompatible) === false) {
								// The save was declined (a concurrent writer updated the shared structures,
								// or the store transaction did not durably commit). Our in-memory
								// structures + transition trie may now reference record ids that were
								// never persisted; re-packing as-is would re-emit the same record pointing
								// at an unpersisted structure (-> "Record id is not defined" on decode).
								// Mark structures uninitialized so the re-pack reloads durable structures
								// via getStructures, rebuilds the transition trie, and re-mints + re-saves.
								structures.uninitialized = true;
								return packr.pack(value, encodeOptions);
							}
							packr.lastNamedStructuresLength = sharedLength;
							// don't keep large buffers around
							if (target.length > 0x40000000) target = null;
							return returnBuffer;
						}
					}
				}
				// don't keep large buffers around, they take too much memory and cause problems (limit at 1GB)
				if (target.length > 0x40000000) target = null;
				if (encodeOptions & RESET_BUFFER_MODE)
					position = start;
			}
		};
		const resetStructures = () => {
			if (serializationsSinceTransitionRebuild < 10)
				serializationsSinceTransitionRebuild++;
			let sharedLength = structures.sharedLength || 0;
			if (structures.length > sharedLength && !isSequential)
				structures.length = sharedLength;
			if (transitionsCount > 10000) {
				// force a rebuild occasionally after a lot of transitions so it can get cleaned up
				structures.transitions = null;
				serializationsSinceTransitionRebuild = 0;
				transitionsCount = 0;
				if (recordIdsToRemove.length > 0)
					recordIdsToRemove = [];
			} else if (recordIdsToRemove.length > 0 && !isSequential) {
				for (let i = 0, l = recordIdsToRemove.length; i < l; i++) {
					recordIdsToRemove[i][RECORD_SYMBOL] = 0;
				}
				recordIdsToRemove = [];
			}
		};
		const packArray = (value) => {
			var length = value.length;
			if (length < 0x10) {
				target[position++] = 0x90 | length;
			} else if (length < 0x10000) {
				target[position++] = 0xdc;
				target[position++] = length >> 8;
				target[position++] = length & 0xff;
			} else {
				target[position++] = 0xdd;
				targetView.setUint32(position, length);
				position += 4;
			}
			for (let i = 0; i < length; i++) {
				pack(value[i]);
			}
		};
		const pack = (value) => {
			if (position > safeEnd)
				target = makeRoom(position);

			var type = typeof value;
			var length;
			if (type === 'string') {
				let strLength = value.length;
				if (bundledStrings && strLength >= 4 && strLength < 0x1000) {
					if ((bundledStrings.size += strLength) > MAX_BUNDLE_SIZE) {
						let extStart;
						let maxBytes = (bundledStrings[0] ? bundledStrings[0].length * 3 + bundledStrings[1].length : 0) + 10;
						if (position + maxBytes > safeEnd)
							target = makeRoom(position + maxBytes);
						let lastBundle;
						if (bundledStrings.position) { // here we use the 0x62 extension to write the last bundle and reserve space for the reference pointer to the next/current bundle
							lastBundle = bundledStrings;
							target[position] = 0xc8; // ext 16
							position += 3; // reserve for the writing bundle size
							target[position++] = 0x62; // 'b'
							extStart = position - start;
							position += 4; // reserve for writing bundle reference
							writeBundles(start, pack, 0); // write the last bundles
							targetView.setUint16(extStart + start - 3, position - start - extStart);
						} else { // here we use the 0x62 extension just to reserve the space for the reference pointer to the bundle (will be updated once the bundle is written)
							target[position++] = 0xd6; // fixext 4
							target[position++] = 0x62; // 'b'
							extStart = position - start;
							position += 4; // reserve for writing bundle reference
						}
						bundledStrings = ['', '']; // create new ones
						bundledStrings.previous = lastBundle;
						bundledStrings.size = 0;
						bundledStrings.position = extStart;
					}
					let twoByte = hasNonLatin.test(value);
					bundledStrings[twoByte ? 0 : 1] += value;
					target[position++] = 0xc1;
					pack(twoByte ? -strLength : strLength);
					return;
				}
				let headerSize;
				// first we estimate the header size, so we can write to the correct location
				if (strLength < 0x20) {
					headerSize = 1;
				} else if (strLength < 0x100) {
					headerSize = 2;
				} else if (strLength < 0x10000) {
					headerSize = 3;
				} else {
					headerSize = 5;
				}
				let maxBytes = strLength * 3;
				if (position + maxBytes > safeEnd)
					target = makeRoom(position + maxBytes);

				if (strLength < 0x40 || !encodeUtf8) {
					let i, c1, c2, strPosition = position + headerSize;
					for (i = 0; i < strLength; i++) {
						c1 = value.charCodeAt(i);
						if (c1 < 0x80) {
							target[strPosition++] = c1;
						} else if (c1 < 0x800) {
							target[strPosition++] = c1 >> 6 | 0xc0;
							target[strPosition++] = c1 & 0x3f | 0x80;
						} else if (
							(c1 & 0xfc00) === 0xd800 &&
							((c2 = value.charCodeAt(i + 1)) & 0xfc00) === 0xdc00
						) {
							c1 = 0x10000 + ((c1 & 0x03ff) << 10) + (c2 & 0x03ff);
							i++;
							target[strPosition++] = c1 >> 18 | 0xf0;
							target[strPosition++] = c1 >> 12 & 0x3f | 0x80;
							target[strPosition++] = c1 >> 6 & 0x3f | 0x80;
							target[strPosition++] = c1 & 0x3f | 0x80;
						} else {
							target[strPosition++] = c1 >> 12 | 0xe0;
							target[strPosition++] = c1 >> 6 & 0x3f | 0x80;
							target[strPosition++] = c1 & 0x3f | 0x80;
						}
					}
					length = strPosition - position - headerSize;
				} else {
					length = encodeUtf8(value, position + headerSize);
				}

				if (length < 0x20) {
					target[position++] = 0xa0 | length;
				} else if (length < 0x100) {
					if (headerSize < 2) {
						target.copyWithin(position + 2, position + 1, position + 1 + length);
					}
					target[position++] = 0xd9;
					target[position++] = length;
				} else if (length < 0x10000) {
					if (headerSize < 3) {
						target.copyWithin(position + 3, position + 2, position + 2 + length);
					}
					target[position++] = 0xda;
					target[position++] = length >> 8;
					target[position++] = length & 0xff;
				} else {
					if (headerSize < 5) {
						target.copyWithin(position + 5, position + 3, position + 3 + length);
					}
					target[position++] = 0xdb;
					targetView.setUint32(position, length);
					position += 4;
				}
				position += length;
			} else if (type === 'number') {
				if (value >>> 0 === value) {// positive integer, 32-bit or less
					// positive uint
					if (value < 0x20 || (value < 0x80 && this.useRecords === false) || (value < 0x40 && !this._writeStruct)) {
						target[position++] = value;
					} else if (value < 0x100) {
						target[position++] = 0xcc;
						target[position++] = value;
					} else if (value < 0x10000) {
						target[position++] = 0xcd;
						target[position++] = value >> 8;
						target[position++] = value & 0xff;
					} else {
						target[position++] = 0xce;
						targetView.setUint32(position, value);
						position += 4;
					}
				} else if (value >> 0 === value) { // negative integer
					if (value >= -0x20) {
						target[position++] = 0x100 + value;
					} else if (value >= -0x80) {
						target[position++] = 0xd0;
						target[position++] = value + 0x100;
					} else if (value >= -0x8000) {
						target[position++] = 0xd1;
						targetView.setInt16(position, value);
						position += 2;
					} else {
						target[position++] = 0xd2;
						targetView.setInt32(position, value);
						position += 4;
					}
				} else {
					let useFloat32;
					if ((useFloat32 = this.useFloat32) > 0 && value < 0x100000000 && value >= -0x80000000) {
						target[position++] = 0xca;
						targetView.setFloat32(position, value);
						let xShifted;
						if (useFloat32 < 4 ||
								// this checks for rounding of numbers that were encoded in 32-bit float to nearest significant decimal digit that could be preserved
								((xShifted = value * mult10[((target[position] & 0x7f) << 1) | (target[position + 1] >> 7)]) >> 0) === xShifted) {
							position += 4;
							return;
						} else
							position--; // move back into position for writing a double
					}
					target[position++] = 0xcb;
					targetView.setFloat64(position, value);
					position += 8;
				}
			} else if (type === 'object' || type === 'function') {
				if (!value)
					target[position++] = 0xc0;
				else {
					if (referenceMap) {
						let referee = referenceMap.get(value);
						if (referee) {
							if (!referee.id) {
								let idsToInsert = referenceMap.idsToInsert || (referenceMap.idsToInsert = []);
								referee.id = idsToInsert.push(referee);
							}
							target[position++] = 0xd6; // fixext 4
							target[position++] = 0x70; // "p" for pointer
							targetView.setUint32(position, referee.id);
							position += 4;
							return;
						} else
							referenceMap.set(value, { offset: position - start });
					}
					let constructor = value.constructor;
					if (constructor === Object) {
						writeObject(value);
					} else if (constructor === Array) {
						packArray(value);
					} else if (constructor === Map) {
						if (this.mapAsEmptyObject) target[position++] = 0x80;
						else {
							length = value.size;
							if (length < 0x10) {
								target[position++] = 0x80 | length;
							} else if (length < 0x10000) {
								target[position++] = 0xde;
								target[position++] = length >> 8;
								target[position++] = length & 0xff;
							} else {
								target[position++] = 0xdf;
								targetView.setUint32(position, length);
								position += 4;
							}
							for (let [key, entryValue] of value) {
								pack(key);
								pack(entryValue);
							}
						}
					} else {
						for (let i = 0, l = extensions.length; i < l; i++) {
							let extensionClass = extensionClasses[i];
							if (value instanceof extensionClass) {
								let extension = extensions[i];
								if (extension.write) {
									if (extension.type) {
										target[position++] = 0xd4; // one byte "tag" extension
										target[position++] = extension.type;
										target[position++] = 0;
									}
									let writeResult = extension.write.call(this, value);
									if (writeResult === value) { // avoid infinite recursion
										if (Array.isArray(value)) {
											packArray(value);
										} else {
											writeObject(value);
										}
									} else {
										pack(writeResult);
									}
									return;
								}
								let currentTarget = target;
								let currentTargetView = targetView;
								let currentPosition = position;
								target = null;
								let result;
								try {
									result = extension.pack.call(this, value, (size) => {
										// restore target and use it
										target = currentTarget;
										currentTarget = null;
										position += size;
										if (position > safeEnd)
											makeRoom(position);
										return {
											target, targetView, position: position - size
										};
									}, pack);
								} finally {
									// restore current target information (unless already restored)
									if (currentTarget) {
										target = currentTarget;
										targetView = currentTargetView;
										position = currentPosition;
										safeEnd = target.length - 10;
									}
								}
								if (result) {
									if (result.length + position > safeEnd)
										makeRoom(result.length + position);
									position = writeExtensionData(result, target, position, extension.type);
								}
								return;
							}
						}
						// check isArray after extensions, because extensions can extend Array
						if (Array.isArray(value)) {
							packArray(value);
						} else {
							// use this as an alternate mechanism for expressing how to serialize
							if (value.toJSON) {
								const json = value.toJSON();
								// if for some reason value.toJSON returns itself it'll loop forever
								if (json !== value)
									return pack(json);
							}

							// if there is a writeFunction, use it, otherwise just encode as undefined
							if (type === 'function')
								return pack(this.writeFunction && this.writeFunction(value));

							// no extension found, write as plain object
							writeObject(value);
						}
					}
				}
			} else if (type === 'boolean') {
				target[position++] = value ? 0xc3 : 0xc2;
			} else if (type === 'bigint') {
				if (value < 0x8000000000000000 && value >= -0x8000000000000000) {
					// use a signed int as long as it fits
					target[position++] = 0xd3;
					targetView.setBigInt64(position, value);
				} else if (value < 0x10000000000000000 && value > 0) {
					// if we can fit an unsigned int, use that
					target[position++] = 0xcf;
					targetView.setBigUint64(position, value);
				} else {
					// overflow
					if (this.largeBigIntToFloat) {
						target[position++] = 0xcb;
						targetView.setFloat64(position, Number(value));
					} else if (this.largeBigIntToString) {
						return pack(value.toString());
					} else if (this.useBigIntExtension || this.moreTypes) {
						let empty = value < 0 ? BigInt(-1) : BigInt(0);

						let array;
						if (value >> BigInt(0x10000) === empty) {
							let mask = BigInt(0x10000000000000000) - BigInt(1); // literal would overflow
							let chunks = [];
							while (true) {
								chunks.push(value & mask);
								if ((value >> BigInt(63)) === empty) break;
								value >>= BigInt(64);
							}

							array = new Uint8Array(new BigUint64Array(chunks).buffer);
							array.reverse();
						} else {
							let invert = value < 0;
							let string = (invert ? ~value : value).toString(16);
							if (string.length % 2) {
								string = '0' + string;
							} else if (parseInt(string.charAt(0), 16) >= 8) {
								string = '00' + string;
							}

							if (hasNodeBuffer) {
								array = Buffer.from(string, 'hex');
							} else {
								array = new Uint8Array(string.length / 2);
								for (let i = 0; i < array.length; i++) {
									array[i] = parseInt(string.slice(i * 2, i * 2 + 2), 16);
								}
							}

							if (invert) {
								for (let i = 0; i < array.length; i++) array[i] = ~array[i];
							}
						}

						if (array.length + position > safeEnd)
							makeRoom(array.length + position);
						position = writeExtensionData(array, target, position, 0x42);
						return;
					} else {
						throw new RangeError(value + ' was too large to fit in MessagePack 64-bit integer format, use' +
							' useBigIntExtension, or set largeBigIntToFloat to convert to float-64, or set' +
							' largeBigIntToString to convert to string');
					}
				}
				position += 8;
			} else if (type === 'undefined') {
				if (this.encodeUndefinedAsNil)
					target[position++] = 0xc0;
				else {
					target[position++] = 0xd4; // a number of implementations use fixext1 with type 0, data 0 to denote undefined, so we follow suite
					target[position++] = 0;
					target[position++] = 0;
				}
			} else {
				throw new Error('Unknown type: ' + type);
			}
		};

		const writePlainObject = (this.variableMapSize || this.coercibleKeyAsNumber || this.skipValues) ? (object) => {
			// this method is slightly slower, but generates "preferred serialization" (optimally small for smaller objects)
			let keys;
			if (this.skipValues) {
				keys = [];
				for (let key in object) {
					if ((typeof object.hasOwnProperty !== 'function' || object.hasOwnProperty(key)) &&
						!this.skipValues.includes(object[key]))
						keys.push(key);
				}
			} else {
				keys = Object.keys(object);
			}
			let length = keys.length;
			if (length < 0x10) {
				target[position++] = 0x80 | length;
			} else if (length < 0x10000) {
				target[position++] = 0xde;
				target[position++] = length >> 8;
				target[position++] = length & 0xff;
			} else {
				target[position++] = 0xdf;
				targetView.setUint32(position, length);
				position += 4;
			}
			let key;
			if (this.coercibleKeyAsNumber) {
				for (let i = 0; i < length; i++) {
					key = keys[i];
					let num = Number(key);
					pack(isNaN(num) ? key : num);
					pack(object[key]);
				}

			} else {
				for (let i = 0; i < length; i++) {
					pack(key = keys[i]);
					pack(object[key]);
				}
			}
		} :
		(object) => {
			target[position++] = 0xde; // always using map 16, so we can preallocate and set the length afterwards
			let objectOffset = position - start;
			position += 2;
			let size = 0;
			for (let key in object) {
				if (typeof object.hasOwnProperty !== 'function' || object.hasOwnProperty(key)) {
					pack(key);
					pack(object[key]);
					size++;
				}
			}
			if (size > 0xffff) {
				throw new Error('Object is too large to serialize with fast 16-bit map size,' +
				' use the "variableMapSize" option to serialize this object');
			}
			target[objectOffset++ + start] = size >> 8;
			target[objectOffset + start] = size & 0xff;
		};

		const writeRecord = this.useRecords === false ? writePlainObject :
		(options.progressiveRecords && !useTwoByteRecords) ?  // this is about 2% faster for highly stable structures, since it only requires one for-in loop (but much more expensive when new structure needs to be written)
		(object) => {
			let nextTransition, transition = structures.transitions || (structures.transitions = Object.create(null));
			let objectOffset = position++ - start;
			let wroteKeys;
			for (let key in object) {
				if (typeof object.hasOwnProperty !== 'function' || object.hasOwnProperty(key)) {
					nextTransition = transition[key];
					if (nextTransition)
						transition = nextTransition;
					else {
						// record doesn't exist, create full new record and insert it
						let keys = Object.keys(object);
						let lastTransition = transition;
						transition = structures.transitions;
						let newTransitions = 0;
						for (let i = 0, l = keys.length; i < l; i++) {
							let key = keys[i];
							nextTransition = transition[key];
							if (!nextTransition) {
								nextTransition = transition[key] = Object.create(null);
								newTransitions++;
							}
							transition = nextTransition;
						}
						if (objectOffset + start + 1 == position) {
							// first key, so we don't need to insert, we can just write record directly
							position--;
							newRecord(transition, keys, newTransitions);
						} else // otherwise we need to insert the record, moving existing data after the record
							insertNewRecord(transition, keys, objectOffset, newTransitions);
						wroteKeys = true;
						transition = lastTransition[key];
					}
					pack(object[key]);
				}
			}
			if (!wroteKeys) {
				let recordId = transition[RECORD_SYMBOL];
				if (recordId)
					target[objectOffset + start] = recordId;
				else
					insertNewRecord(transition, Object.keys(object), objectOffset, 0);
			}
		} :
		(object) => {
			let nextTransition, transition = structures.transitions || (structures.transitions = Object.create(null));
			let newTransitions = 0;
			for (let key in object) if (typeof object.hasOwnProperty !== 'function' || object.hasOwnProperty(key)) {
				nextTransition = transition[key];
				if (!nextTransition) {
					nextTransition = transition[key] = Object.create(null);
					newTransitions++;
				}
				transition = nextTransition;
			}
			let recordId = transition[RECORD_SYMBOL];
			if (recordId) {
				if (recordId >= 0x60 && useTwoByteRecords) {
					target[position++] = ((recordId -= 0x60) & 0x1f) + 0x60;
					target[position++] = recordId >> 5;
				} else
					target[position++] = recordId;
			} else {
				newRecord(transition, transition.__keys__ || Object.keys(object), newTransitions);
			}
			// now write the values
			for (let key in object)
				if (typeof object.hasOwnProperty !== 'function' || object.hasOwnProperty(key)) {
					pack(object[key]);
				}
		};

		// create reference to useRecords if useRecords is a function
		const checkUseRecords = typeof this.useRecords == 'function' && this.useRecords;

		const writeObject = checkUseRecords ? (object) => {
			checkUseRecords(object) ? writeRecord(object) : writePlainObject(object);
		} : writeRecord;

		const writeStruct = (object) => {
			let newPosition = packr._writeStruct(object, target, start, position, structures, makeRoom, (value, newPosition, notifySharedUpdate) => {
				if (notifySharedUpdate)
					return hasSharedUpdate = true;
				position = newPosition;
				let startTarget = target;
				pack(value);
				resetStructures();
				if (startTarget !== target) {
					return { position, targetView, target }; // indicate the buffer was re-allocated
				}
				return position;
			});
			if (newPosition === 0) // bail and go to a msgpack object
				return writeObject(object);
			position = newPosition;
		};

		const makeRoom = (end) => {
			let newSize;
			if (end > 0x1000000) {
				// special handling for really large buffers
				if ((end - start) > MAX_BUFFER_SIZE)
					throw new Error('Packed buffer would be larger than maximum buffer size');
				newSize = Math.min(MAX_BUFFER_SIZE,
					Math.round(Math.max((end - start) * (end > 0x4000000 ? 1.25 : 2), 0x400000) / 0x1000) * 0x1000);
			} else // faster handling for smaller buffers
				newSize = ((Math.max((end - start) << 2, target.length - 1) >> 12) + 1) << 12;
			let newBuffer = new ByteArrayAllocate(newSize);
			targetView = newBuffer.dataView || (newBuffer.dataView = new DataView(newBuffer.buffer, 0, newSize));
			end = Math.min(end, target.length);
			if (target.copy)
				target.copy(newBuffer, 0, start, end);
			else
				newBuffer.set(target.slice(start, end));
			position -= start;
			start = 0;
			safeEnd = newBuffer.length - 10;
			return target = newBuffer;
		};
		const newRecord = (transition, keys, newTransitions) => {
			let recordId = structures.nextId;
			if (!recordId)
				recordId = 0x40;
			if (recordId < sharedLimitId && this.shouldShareStructure && !this.shouldShareStructure(keys)) {
				recordId = structures.nextOwnId;
				if (!(recordId < maxStructureId))
					recordId = sharedLimitId;
				structures.nextOwnId = recordId + 1;
			} else {
				if (recordId >= maxStructureId)// cycle back around
					recordId = sharedLimitId;
				structures.nextId = recordId + 1;
			}
			let highByte = keys.highByte = recordId >= 0x60 && useTwoByteRecords ? (recordId - 0x60) >> 5 : -1;
			transition[RECORD_SYMBOL] = recordId;
			transition.__keys__ = keys;
			structures[recordId - 0x40] = keys;

			if (recordId < sharedLimitId) {
				keys.isShared = true;
				structures.sharedLength = recordId - 0x3f;
				hasSharedUpdate = true;
				if (highByte >= 0) {
					target[position++] = (recordId & 0x1f) + 0x60;
					target[position++] = highByte;
				} else {
					target[position++] = recordId;
				}
			} else {
				if (highByte >= 0) {
					target[position++] = 0xd5; // fixext 2
					target[position++] = 0x72; // "r" record defintion extension type
					target[position++] = (recordId & 0x1f) + 0x60;
					target[position++] = highByte;
				} else {
					target[position++] = 0xd4; // fixext 1
					target[position++] = 0x72; // "r" record defintion extension type
					target[position++] = recordId;
				}

				if (newTransitions)
					transitionsCount += serializationsSinceTransitionRebuild * newTransitions;
				// record the removal of the id, we can maintain our shared structure
				if (recordIdsToRemove.length >= maxOwnStructures)
					recordIdsToRemove.shift()[RECORD_SYMBOL] = 0; // we are cycling back through, and have to remove old ones
				recordIdsToRemove.push(transition);
				pack(keys);
			}
		};
		const insertNewRecord = (transition, keys, insertionOffset, newTransitions) => {
			let mainTarget = target;
			let mainPosition = position;
			let mainSafeEnd = safeEnd;
			let mainStart = start;
			target = keysTarget;
			position = 0;
			start = 0;
			if (!target)
				keysTarget = target = new ByteArrayAllocate(8192);
			safeEnd = target.length - 10;
			newRecord(transition, keys, newTransitions);
			keysTarget = target;
			let keysPosition = position;
			target = mainTarget;
			position = mainPosition;
			safeEnd = mainSafeEnd;
			start = mainStart;
			if (keysPosition > 1) {
				let newEnd = position + keysPosition - 1;
				if (newEnd > safeEnd)
					makeRoom(newEnd);
				let insertionPosition = insertionOffset + start;
				target.copyWithin(insertionPosition + keysPosition, insertionPosition + 1, position);
				target.set(keysTarget.slice(0, keysPosition), insertionPosition);
				position = newEnd;
			} else {
				target[insertionOffset + start] = keysTarget[0];
			}
		};
	}
	useBuffer(buffer) {
		// this means we are finished using our own buffer and we can write over it safely
		target = buffer;
		target.dataView || (target.dataView = new DataView(target.buffer, target.byteOffset, target.byteLength));
		targetView = target.dataView;
		position = 0;
	}
	set position (value) {
		position = value;
	}
	get position() {
		return position;
	}
	clearSharedData() {
		if (this.structures)
			this.structures = [];
		if (this.typedStructs)
			this.typedStructs = [];
	}
}

extensionClasses = [ Date, Set, Error, RegExp, ArrayBuffer, Object.getPrototypeOf(Uint8Array.prototype).constructor /*TypedArray*/, DataView, C1Type ];
extensions = [{
	pack(date, allocateForWrite, pack) {
		let seconds = date.getTime() / 1000;
		if ((this.useTimestamp32 || date.getMilliseconds() === 0) && seconds >= 0 && seconds < 0x100000000) {
			// Timestamp 32
			let { target, targetView, position} = allocateForWrite(6);
			target[position++] = 0xd6;
			target[position++] = 0xff;
			targetView.setUint32(position, seconds);
		} else if (seconds > 0 && seconds < 0x100000000) {
			// Timestamp 64
			let { target, targetView, position} = allocateForWrite(10);
			target[position++] = 0xd7;
			target[position++] = 0xff;
			targetView.setUint32(position, date.getMilliseconds() * 4000000 + ((seconds / 1000 / 0x100000000) >> 0));
			targetView.setUint32(position + 4, seconds);
		} else if (isNaN(seconds)) {
			if (this.onInvalidDate) {
				allocateForWrite(0);
				return pack(this.onInvalidDate());
			}
			// Intentionally invalid timestamp
			let { target, targetView, position} = allocateForWrite(3);
			target[position++] = 0xd4;
			target[position++] = 0xff;
			target[position++] = 0xff;
		} else {
			// Timestamp 96
			let { target, targetView, position} = allocateForWrite(15);
			target[position++] = 0xc7;
			target[position++] = 12;
			target[position++] = 0xff;
			targetView.setUint32(position, date.getMilliseconds() * 1000000);
			targetView.setBigInt64(position + 4, BigInt(Math.floor(seconds)));
		}
	}
}, {
	pack(set, allocateForWrite, pack) {
		if (this.setAsEmptyObject) {
			allocateForWrite(0);
			return pack({});
		}
		let array = Array.from(set);
		let { target, position} = allocateForWrite(this.moreTypes ? 3 : 0);
		if (this.moreTypes) {
			target[position++] = 0xd4;
			target[position++] = 0x73; // 's' for Set
			target[position++] = 0;
		}
		pack(array);
	}
}, {
	pack(error, allocateForWrite, pack) {
		let { target, position} = allocateForWrite(this.moreTypes ? 3 : 0);
		if (this.moreTypes) {
			target[position++] = 0xd4;
			target[position++] = 0x65; // 'e' for error
			target[position++] = 0;
		}
		pack([ error.name, error.message, error.cause ]);
	}
}, {
	pack(regex, allocateForWrite, pack) {
		let { target, position} = allocateForWrite(this.moreTypes ? 3 : 0);
		if (this.moreTypes) {
			target[position++] = 0xd4;
			target[position++] = 0x78; // 'x' for regeXp
			target[position++] = 0;
		}
		pack([ regex.source, regex.flags ]);
	}
}, {
	pack(arrayBuffer, allocateForWrite) {
		if (this.moreTypes)
			writeExtBuffer(arrayBuffer, 0x10, allocateForWrite);
		else
			writeBuffer(hasNodeBuffer ? Buffer.from(arrayBuffer) : new Uint8Array(arrayBuffer), allocateForWrite);
	}
}, {
	pack(typedArray, allocateForWrite) {
		let constructor = typedArray.constructor;
		if (constructor !== ByteArray && this.moreTypes)
			writeExtBuffer(typedArray, typedArrays.indexOf(constructor.name), allocateForWrite);
		else
			writeBuffer(typedArray, allocateForWrite);
	}
}, {
	pack(arrayBuffer, allocateForWrite) {
		if (this.moreTypes)
			writeExtBuffer(arrayBuffer, 0x11, allocateForWrite);
		else
			writeBuffer(hasNodeBuffer ? Buffer.from(arrayBuffer) : new Uint8Array(arrayBuffer), allocateForWrite);
	}
}, {
	pack(c1, allocateForWrite) { // specific 0xC1 object
		let { target, position} = allocateForWrite(1);
		target[position] = 0xc1;
	}
}];

function writeExtBuffer(typedArray, type, allocateForWrite, encode) {
	let length = typedArray.byteLength;
	if (length + 1 < 0x100) {
		var { target, position } = allocateForWrite(4 + length);
		target[position++] = 0xc7;
		target[position++] = length + 1;
	} else if (length + 1 < 0x10000) {
		var { target, position } = allocateForWrite(5 + length);
		target[position++] = 0xc8;
		target[position++] = (length + 1) >> 8;
		target[position++] = (length + 1) & 0xff;
	} else {
		var { target, position, targetView } = allocateForWrite(7 + length);
		target[position++] = 0xc9;
		targetView.setUint32(position, length + 1); // plus one for the type byte
		position += 4;
	}
	target[position++] = 0x74; // "t" for typed array
	target[position++] = type;
	if (!typedArray.buffer) typedArray = new Uint8Array(typedArray);
	target.set(new Uint8Array(typedArray.buffer, typedArray.byteOffset, typedArray.byteLength), position);
}
function writeBuffer(buffer, allocateForWrite) {
	let length = buffer.byteLength;
	var target, position;
	if (length < 0x100) {
		var { target, position } = allocateForWrite(length + 2);
		target[position++] = 0xc4;
		target[position++] = length;
	} else if (length < 0x10000) {
		var { target, position } = allocateForWrite(length + 3);
		target[position++] = 0xc5;
		target[position++] = length >> 8;
		target[position++] = length & 0xff;
	} else {
		var { target, position, targetView } = allocateForWrite(length + 5);
		target[position++] = 0xc6;
		targetView.setUint32(position, length);
		position += 4;
	}
	target.set(buffer, position);
}

function writeExtensionData(result, target, position, type) {
	let length = result.length;
	switch (length) {
		case 1:
			target[position++] = 0xd4;
			break;
		case 2:
			target[position++] = 0xd5;
			break;
		case 4:
			target[position++] = 0xd6;
			break;
		case 8:
			target[position++] = 0xd7;
			break;
		case 16:
			target[position++] = 0xd8;
			break;
		default:
			if (length < 0x100) {
				target[position++] = 0xc7;
				target[position++] = length;
			} else if (length < 0x10000) {
				target[position++] = 0xc8;
				target[position++] = length >> 8;
				target[position++] = length & 0xff;
			} else {
				target[position++] = 0xc9;
				target[position++] = length >> 24;
				target[position++] = (length >> 16) & 0xff;
				target[position++] = (length >> 8) & 0xff;
				target[position++] = length & 0xff;
			}
	}
	target[position++] = type;
	target.set(result, position);
	position += length;
	return position;
}

function insertIds(serialized, idsToInsert) {
	// insert the ids that need to be referenced for structured clones
	let nextId;
	let distanceToMove = idsToInsert.length * 6;
	let lastEnd = serialized.length - distanceToMove;
	while (nextId = idsToInsert.pop()) {
		let offset = nextId.offset;
		let id = nextId.id;
		serialized.copyWithin(offset + distanceToMove, offset, lastEnd);
		distanceToMove -= 6;
		let position = offset + distanceToMove;
		serialized[position++] = 0xd6;
		serialized[position++] = 0x69; // 'i'
		serialized[position++] = id >> 24;
		serialized[position++] = (id >> 16) & 0xff;
		serialized[position++] = (id >> 8) & 0xff;
		serialized[position++] = id & 0xff;
		lastEnd = offset;
	}
	return serialized;
}

function writeBundles(start, pack, incrementPosition) {
	if (bundledStrings.length > 0) {
		targetView.setUint32(bundledStrings.position + start, position + incrementPosition - bundledStrings.position - start);
		bundledStrings.stringsPosition = position - start;
		let writeStrings = bundledStrings;
		bundledStrings = null;
		pack(writeStrings[0]);
		pack(writeStrings[1]);
	}
}

export function addExtension(extension) {
	if (extension.Class) {
		if (!extension.pack && !extension.write)
			throw new Error('Extension has no pack or write function');
		if (extension.pack && !extension.type)
			throw new Error('Extension has no type (numeric code to identify the extension)');
		extensionClasses.unshift(extension.Class);
		extensions.unshift(extension);
	}
	unpackAddExtension(extension);
}
function prepareStructures(structures, packr) {
	structures.isCompatible = (existingStructures) => {
		let compatible = !existingStructures || ((packr.lastNamedStructuresLength || 0) === existingStructures.length);
		if (!compatible) // we want to merge these existing structures immediately since we already have it and we are in the right transaction
			packr._mergeStructures(existingStructures);
		return compatible;
	};
	return structures;
}

// Marker for downstream libraries (e.g. structon) to detect that this Packr
// supports per-instance struct-encoding hooks (this._writeStruct,
// this._prepareStructures).  See `pack` for the dispatch.
Packr.SUPPORTS_STRUCT_HOOKS = true;

let defaultPackr = new Packr({ useRecords: false });
export const pack = defaultPackr.pack;
export const encode = defaultPackr.pack;
export const Encoder = Packr;
export { FLOAT32_OPTIONS } from './unpack.js';
import { FLOAT32_OPTIONS } from './unpack.js';
export const { NEVER, ALWAYS, DECIMAL_ROUND, DECIMAL_FIT } = FLOAT32_OPTIONS;
export const REUSE_BUFFER_MODE = 512;
export const RESET_BUFFER_MODE = 1024;
export const RESERVE_START_SPACE = 2048;