/*
 * Copyright (c) 2016-2023 Martin Donath <martin.donath@squidfunk.com>
 *
 * 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 NON-INFRINGEMENT. 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.
 */

import { split } from "../../internal"
import { transform } from "../transform"

/* ----------------------------------------------------------------------------
 * Types
 * ------------------------------------------------------------------------- */

/**
 * Search query clause
 */
export interface SearchQueryClause {
  presence: lunr.Query.presence        /* Clause presence */
  term: string                         /* Clause term */
}

/* ------------------------------------------------------------------------- */

/**
 * Search query terms
 */
export type SearchQueryTerms = Record<string, boolean>

/* ----------------------------------------------------------------------------
 * Functions
 * ------------------------------------------------------------------------- */

/**
 * Transform search query
 *
 * This function lexes the given search query and applies the transformation
 * function to each term, preserving markup like `+` and `-` modifiers.
 *
 * @param query - Search query
 *
 * @returns Search query
 */
export function transformSearchQuery(
  query: string
): string {

  /* Split query terms with tokenizer */
  return transform(query, part => {
    const terms: string[] = []

    /* Initialize lexer and analyze part */
    const lexer = new lunr.QueryLexer(part)
    lexer.run()

    /* Extract and tokenize term from lexeme */
    for (const { type, str: term, start, end } of lexer.lexemes)
      switch (type) {

        /* Hack: remove colon - see https://bit.ly/3wD3T3I */
        case "FIELD":
          if (!["title", "text", "tags"].includes(term))
            part = [
              part.slice(0, end),
              " ",
              part.slice(end + 1)
            ].join("")
          break

        /* Tokenize term */
        case "TERM":
          split(term, lunr.tokenizer.separator, (...range) => {
            terms.push([
              part.slice(0, start),
              term.slice(...range),
              part.slice(end)
            ].join(""))
          })
      }

    /* Return terms */
    return terms
  })
}

/* ------------------------------------------------------------------------- */

/**
 * Parse a search query for analysis
 *
 * Lunr.js itself has a bug where it doesn't detect or remove wildcards for
 * query clauses, so we must do this here.
 *
 * @see https://bit.ly/3DpTGtz - GitHub issue
 *
 * @param value - Query value
 *
 * @returns Search query clauses
 */
export function parseSearchQuery(
  value: string
): SearchQueryClause[] {
  const query  = new lunr.Query(["title", "text", "tags"])
  const parser = new lunr.QueryParser(value, query)

  /* Parse Search query */
  parser.parse()
  for (const clause of query.clauses) {
    clause.usePipeline = true

    /* Handle leading wildcard */
    if (clause.term.startsWith("*")) {
      clause.wildcard = lunr.Query.wildcard.LEADING
      clause.term = clause.term.slice(1)
    }

    /* Handle trailing wildcard */
    if (clause.term.endsWith("*")) {
      clause.wildcard = lunr.Query.wildcard.TRAILING
      clause.term = clause.term.slice(0, -1)
    }
  }

  /* Return query clauses */
  return query.clauses
}

/**
 * Analyze the search query clauses in regard to the search terms found
 *
 * @param query - Search query clauses
 * @param terms - Search terms
 *
 * @returns Search query terms
 */
export function getSearchQueryTerms(
  query: SearchQueryClause[], terms: string[]
): SearchQueryTerms {
  const clauses = new Set<SearchQueryClause>(query)

  /* Match query clauses against terms */
  const result: SearchQueryTerms = {}
  for (let t = 0; t < terms.length; t++)
    for (const clause of clauses)
      if (terms[t].startsWith(clause.term)) {
        result[clause.term] = true
        clauses.delete(clause)
      }

  /* Annotate unmatched non-stopword query clauses */
  for (const clause of clauses)
    if (lunr.stopWordFilter?.(clause.term))
      result[clause.term] = false

  /* Return query terms */
  return result
}