import Sequence from "./Sequence";

export interface JoinConfig<T> {

value?: string;

separator?: string;

prefix?: string;

postfix?: string;

limit?: number;

truncated?: string;

transform?: (value: T) => string;

}

const defaults = {

value: "",

separator: ", ",

prefix: "",

postfix: "",

limit: -1,

truncated: "...",

transform: undefined

};

export class JoinToString {

/**

* Joins all elements of the sequence into a string with the given configuration.

*

* @param {JoinConfig<T>} config

* @returns {string}

*/

joinToString<T>(this: Sequence<T>, config: JoinConfig<T> = defaults): string {

const {

value = defaults.value,

separator = defaults.separator,

prefix = defaults.prefix,

postfix = defaults.postfix,

limit = defaults.limit,

truncated = defaults.truncated,

transform = defaults.transform

} = config;

let result = `${value}${prefix}`;

let count = 0;

for (let item = this.iterator.next(); !item.done; item = this.iterator.next()) {

count++;

if (count > 1) {

result += separator;

}

if (limit < 0 || count <= limit) {

result += transform != null

? transform(item.value)

: String(item.value);

} else {

break;

}

}

if (limit >= 0 && count > limit) {

result += truncated;

}

result += postfix;

return result;

}

/**

* Joins all elements of the sequence into a string with the given configuration.

*

* @param {JoinConfig<T>} config

* @returns {string}

*/

joinTo<T>(this: Sequence<T>, config: JoinConfig<T> = defaults): string {

return this.joinToString(config);

}

}