HStr.ts

/*
 * Copyright (c) 2020, J2 Innovations. All Rights Reserved
 */

import { Kind } from './Kind'
import {
	HVal,
	CANNOT_CHANGE_READONLY_VALUE,
	valueInspect,
	valueIsKind,
	valueMatches,
} from './HVal'
import { Node } from '../filter/Node'
import { HGrid } from './HGrid'
import { HList } from './HList'
import { HDict } from './HDict'
import { EvalContext } from '../filter/EvalContext'

let emptyStr: HStr

/**
 * Haystack string.
 */
export class HStr implements HVal {
	/**
	 * The string value.
	 */
	readonly #value: string

	/**
	 * Constructs a new haystack string.
	 *
	 * @param value The value.
	 */
	private constructor(value: string) {
		this.#value = value
	}

	/**
	 * Makes a haystack string.
	 *
	 * @param value The value string.
	 * @returns A haystack string.
	 */
	public static make(value: string | HStr): HStr {
		if (typeof value === 'string') {
			return value
				? new HStr(value)
				: emptyStr ?? Object.freeze((emptyStr = new HStr(value)))
		} else {
			return value
		}
	}

	/**
	 * @returns The string value.
	 */
	public get value(): string {
		return this.#value
	}

	public set value(value: string) {
		throw new Error(CANNOT_CHANGE_READONLY_VALUE)
	}

	/**
	 * @returns The value's kind.
	 */
	public getKind(): Kind {
		return Kind.Str
	}

	/**
	 * Compares the value's kind.
	 *
	 * @param kind The kind to compare against.
	 * @returns True if the kind matches.
	 */
	public isKind(kind: Kind): boolean {
		return valueIsKind<HStr>(this, kind)
	}

	/**
	 * Returns true if the haystack filter matches the value.
	 *
	 * @param filter The filter to test.
	 * @param cx Optional haystack filter evaluation context.
	 * @returns True if the filter matches ok.
	 */
	public matches(filter: string | Node, cx?: Partial<EvalContext>): boolean {
		return valueMatches(this, filter, cx)
	}

	/**
	 * Dump the value to the local console output.
	 *
	 * @param message An optional message to display before the value.
	 * @returns The value instance.
	 */
	public inspect(message?: string): this {
		return valueInspect(this, message)
	}

	/**
	 * Encodes to an encoded zinc value that can be used
	 * in a haystack filter string.
	 *
	 * The encoding for a haystack filter is mostly zinc but contains
	 * some exceptions.
	 *
	 * @returns The encoded value that can be used in a haystack filter.
	 */
	public toFilter(): string {
		return this.toZinc()
	}

	/**
	 * Value equality check.
	 *
	 * @param value The value to test.
	 * @returns True if the value is the same.
	 */
	public equals(value: HStr): boolean {
		return valueIsKind<HStr>(value, Kind.Str) && this.value === value.value
	}

	/**
	 * Compares two values.
	 *
	 * @param value The value to compare against.
	 * @returns The sort order as negative, 0, or positive
	 */
	public compareTo(value: unknown): number {
		if (!valueIsKind<HStr>(value, Kind.Str)) {
			return -1
		}

		if (this.value < value.value) {
			return -1
		}
		if (this.value === value.value) {
			return 0
		}
		return 1
	}

	/**
	 * @returns The object's value as a string.
	 */
	public valueOf(): string {
		return this.value
	}

	/**
	 * @returns A string representation of the value.
	 */
	public toString(): string {
		return this.value
	}

	/**
	 * Encode to zinc encoding.
	 *
	 * @returns The encoded zinc string.
	 */
	public toZinc(): string {
		let buf = '"'

		for (const c of this.value) {
			const code = c.charCodeAt(0)
			if (
				c < ' ' ||
				c === '"' ||
				c === '\\' ||
				c === '$' ||
				code >= 128
			) {
				buf += '\\'
				switch (c) {
					case '\b':
						buf += 'b'
						break
					case '\f':
						buf += 'f'
						break
					case '\n':
						buf += 'n'
						break
					case '\r':
						buf += 'r'
						break
					case '\t':
						buf += 't'
						break
					case '"':
						buf += '"'
						break
					case '\\':
						buf += '\\'
						break
					case '$':
						buf += '$'
						break
					default:
						let seq = code.toString(16)

						// Make sure we have four characters for the unicode sequence.
						while (seq.length < 4) {
							seq = `0${seq}`
						}

						buf += `u${seq}`
				}
			} else {
				buf += c
			}
		}

		buf += '"'

		return buf
	}

	/**
	 * @returns A JSON reprentation of the object.
	 */
	public toJSON(): string {
		return this.value
	}

	/**
	 * @returns A JSON v3 representation of the object.
	 */
	public toJSONv3(): string {
		return this.value.includes(':') ? `s:${this.value}` : this.value
	}

	/**
	 * @returns An Axon encoded string of the value.
	 */
	public toAxon(): string {
		return this.toZinc()
	}

	/**
	 * @returns Returns the value instance.
	 */
	public newCopy(): HStr {
		return this
	}

	/**
	 * @returns The value as a grid.
	 */
	public toGrid(): HGrid {
		return HGrid.make(this)
	}

	/**
	 * @returns The value as a list.
	 */
	public toList(): HList<HStr> {
		return HList.make(this)
	}

	/**
	 * @returns The value as a dict.
	 */
	public toDict(): HDict {
		return HDict.make(this)
	}
}