import { type HeaderValue } from './header-value.ts'
import { quoteEtag } from './utils.ts'

/**
 * Initializer for an `If-None-Match` header value.
 */
export interface IfNoneMatchInit {
  /**
   * The entity tags to compare against the current entity.
   */
  tags: string[]
}

/**
 * The value of an `If-None-Match` HTTP header.
 *
 * [MDN `If-None-Match` Reference](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/If-None-Match)
 *
 * [HTTP/1.1 Specification](https://datatracker.ietf.org/doc/html/rfc7232#section-3.2)
 */
export class IfNoneMatch implements HeaderValue, IfNoneMatchInit {
  tags: string[] = []

  constructor(init?: string | string[] | IfNoneMatchInit) {
    if (init) return IfNoneMatch.from(init)
  }

  /**
   * Checks if the header contains the given entity tag.
   *
   * Note: This method checks only for exact matches and does not consider wildcards.
   *
   * @param tag The entity tag to check for
   * @returns `true` if the tag is present in the header, `false` otherwise
   */
  has(tag: string): boolean {
    return this.tags.includes(quoteEtag(tag))
  }

  /**
   * Checks if this header matches the given entity tag.
   *
   * @param tag The entity tag to check for
   * @returns `true` if the tag is present in the header (or the header contains a wildcard), `false` otherwise
   */
  matches(tag: string): boolean {
    return this.has(tag) || this.tags.includes('*')
  }

  /**
   * Returns the string representation of the header value.
   *
   * @returns The header value as a string
   */
  toString() {
    return this.tags.join(', ')
  }

  /**
   * Parse an If-None-Match header value.
   *
   * @param value The header value (string, string[], init object, or null)
   * @returns An IfNoneMatch instance (empty if null)
   */
  static from(value: string | string[] | IfNoneMatchInit | null): IfNoneMatch {
    let header = new IfNoneMatch()

    if (value !== null) {
      if (typeof value === 'string') {
        header.tags.push(...value.split(/\s*,\s*/).map(quoteEtag))
      } else if (Array.isArray(value)) {
        header.tags.push(...value.map(quoteEtag))
      } else {
        header.tags.push(...value.tags.map(quoteEtag))
      }
    }

    return header
  }
}