R/KorAPQuery.R

#' Class KorAPQuery
#'
#' This class provides methods to perform different kinds of queries on the KorAP API server.
#' `KorAPQuery` objects, which are typically created by the [corpusQuery()] method,
#' represent the current state of a query to a KorAP server.
#'
#' @include KorAPConnection.R
#' @include logging.R
#' @import httr2
#'
#' @include RKorAPClient-package.R

#' @export
KorAPQuery <- setClass("KorAPQuery", slots = c(
  "korapConnection",
  "request",
  "vc",
  "totalResults",
  "nextStartIndex",
  "fields",
  "requestUrl",
  "webUIRequestUrl",
  "apiResponse",
  "collectedMatches",
  "hasMoreMatches"
))

#' Method initialize
#'
#' @rdname KorAPQuery-class
#' @param .Object …
#' @param korapConnection KorAPConnection object
#' @param request query part of the request URL
#' @param vc definition of a virtual corpus
#' @param totalResults number of hits the query has yielded
#' @param nextStartIndex at what index to start the next fetch of query results
#' @param fields what data / metadata fields should be collected
#' @param requestUrl complete URL of the API request
#' @param webUIRequestUrl URL of a web frontend request corresponding to the API request
#' @param apiResponse data-frame representation of the JSON response of the API request
#' @param hasMoreMatches logical that signals if more query results can be fetched
#' @param collectedMatches matches already fetched from the KorAP-API-server
#'
#' @importFrom tibble tibble
#' @export
setMethod(
  "initialize", "KorAPQuery",
  function(.Object, korapConnection = NULL, request = NULL, vc = "", totalResults = 0, nextStartIndex = 0, fields = c(
             "corpusSigle", "textSigle", "pubDate", "pubPlace",
             "availability", "textClass", "snippet", "tokens"
           ),
           requestUrl = "", webUIRequestUrl = "", apiResponse = NULL, hasMoreMatches = FALSE, collectedMatches = NULL) {
    .Object <- callNextMethod()
    .Object@korapConnection <- korapConnection
    .Object@request <- request
    .Object@vc <- vc
    .Object@totalResults <- totalResults
    .Object@nextStartIndex <- nextStartIndex
    .Object@fields <- fields
    .Object@requestUrl <- requestUrl
    .Object@webUIRequestUrl <- webUIRequestUrl
    .Object@apiResponse <- apiResponse
    .Object@hasMoreMatches <- hasMoreMatches
    .Object@collectedMatches <- collectedMatches
    .Object
  }
)

setGeneric("corpusQuery", function(kco, ...) standardGeneric("corpusQuery"))
setGeneric("fetchAll", function(kqo, ...) standardGeneric("fetchAll"))
setGeneric("fetchNext", function(kqo, ...) standardGeneric("fetchNext"))
setGeneric("fetchRest", function(kqo, ...) standardGeneric("fetchRest"))
setGeneric("frequencyQuery", function(kco, ...) standardGeneric("frequencyQuery"))

maxResultsPerPage <- 50

## quiets concerns of R CMD check re: the .'s that appear in pipelines
utils::globalVariables(c("."))

#' Corpus query
#'
#' **`corpusQuery`** performs a corpus query via a connection to a KorAP-API-server
#'
#' @rdname KorAPQuery-class
#' @aliases corpusQuery
#'
#' @importFrom urltools url_encode
#' @importFrom purrr pmap
#' @importFrom dplyr bind_rows
#'
#' @param kco [KorAPConnection()] object (obtained e.g. from `KorAPConnection()`
#' @param query string that contains the corpus query. The query language depends on the `ql` parameter. Either `query` must be provided or `KorAPUrl`.
#' @param vc string describing the virtual corpus in which the query should be performed. An empty string (default) means the whole corpus, as far as it is license-wise accessible.
#' @param KorAPUrl instead of providing the query and vc string parameters, you can also simply copy a KorAP query URL from your browser and use it here (and in `KorAPConnection`) to provide all necessary information for the query.
#' @param metadataOnly logical that determines whether queries should return only metadata without any snippets. This can also be useful to prevent access rewrites. Note that the default value is TRUE.
#'    If you want your corpus queries to return not only metadata, but also KWICS, you need to authorize
#'    your RKorAPClient application as explained in the
#'   [authorization section](https://github.com/KorAP/RKorAPClient#authorization)
#'   of the RKorAPClient Readme on GitHub and set the `metadataOnly` parameter to
#'   `FALSE`.
#' @param ql string to choose the query language (see [section on Query Parameters](https://github.com/KorAP/Kustvakt/wiki/Service:-Search-GET#user-content-parameters) in the Kustvakt-Wiki for possible values.
#' @param fields (meta)data fields that will be fetched for every match.
#' @param accessRewriteFatal abort if query or given vc had to be rewritten due to insufficient rights (not yet implemented).
#' @param verbose print some info
#' @param as.df return result as data frame instead of as S4 object?
#' @param expand logical that decides if `query` and `vc` parameters are expanded to all of their combinations. Defaults to `TRUE`, iff `query` and `vc` have different lengths
#' @param context string that specifies the size of the left and the right context returned in `snippet`
#'        (provided that `metadataOnly` is set to `false` and that the necessary access right are  met).
#'        The format of the context size specifcation (e.g. `3-token,3-token`) is described in the [Service: Search GET documentation of the Kustvakt Wiki](https://github.com/KorAP/Kustvakt/wiki/Service:-Search-GET).
#'        If the parameter is not set, the default context size secification of the KorAP server instance will be used.
#'        Note that you cannot overrule the maximum context size set in the KorAP server instance,
#'        as this is typically legally motivated.
#' @return Depending on the `as.df` parameter, a tibble or a [KorAPQuery()] object that, among other information, contains the total number of results in `@totalResults`. The resulting object can be used to fetch all query results (with [fetchAll()]) or the next page of results (with [fetchNext()]).
#' A corresponding URL to be used within a web browser is contained in `@webUIRequestUrl`
#' Please make sure to check `$collection$rewrites` to see if any unforeseen access rewrites of the query's virtual corpus had to be performed.
#'
#' @examples
#' \dontrun{
#'
#' # Fetch metadata of every query hit for "Ameisenplage" and show a summary
#' KorAPConnection() %>%
#'   corpusQuery("Ameisenplage") %>%
#'   fetchAll()
#' }
#'
#' \dontrun{
#'
#' # Use the copy of a KorAP-web-frontend URL for an API query of "Ameise" in a virtual corpus
#' # and show the number of query hits (but don't fetch them).
#'
#' KorAPConnection(verbose = TRUE) %>%
#'   corpusQuery(
#'     KorAPUrl =
#'       "https://korap.ids-mannheim.de/?q=Ameise&cq=pubDate+since+2017&ql=poliqarp"
#'   )
#' }
#'
#' \dontrun{
#'
#' # Plot the time/frequency curve of "Ameisenplage"
#' KorAPConnection(verbose = TRUE) %>%
#'   {
#'     . ->> kco
#'   } %>%
#'   corpusQuery("Ameisenplage") %>%
#'   fetchAll() %>%
#'   slot("collectedMatches") %>%
#'   mutate(year = lubridate::year(pubDate)) %>%
#'   dplyr::select(year) %>%
#'   group_by(year) %>%
#'   summarise(Count = dplyr::n()) %>%
#'   mutate(Freq = mapply(function(f, y) {
#'     f / corpusStats(kco, paste("pubDate in", y))@tokens
#'   }, Count, year)) %>%
#'   dplyr::select(-Count) %>%
#'   complete(year = min(year):max(year), fill = list(Freq = 0)) %>%
#'   plot(type = "l")
#' }
#' @seealso [KorAPConnection()], [fetchNext()], [fetchRest()], [fetchAll()], [corpusStats()]
#'
#' @references
#' <https://ids-pub.bsz-bw.de/frontdoor/index/index/docId/9026>
#'
#' @export
setMethod(
  "corpusQuery", "KorAPConnection",
  function(kco,
           query = if (missing(KorAPUrl)) {
             stop("At least one of the parameters query and KorAPUrl must be specified.", call. = FALSE)
           } else {
             httr2::url_parse(KorAPUrl)$query$q
           },
           vc = if (missing(KorAPUrl)) "" else httr2::url_parse(KorAPUrl)$query$cq,
           KorAPUrl,
           metadataOnly = TRUE,
           ql = if (missing(KorAPUrl)) "poliqarp" else httr2::url_parse(KorAPUrl)$query$ql,
           fields = c(
             "corpusSigle",
             "textSigle",
             "pubDate",
             "pubPlace",
             "availability",
             "textClass",
             "snippet",
             "tokens"
           ),
           accessRewriteFatal = TRUE,
           verbose = kco@verbose,
           expand = length(vc) != length(query),
           as.df = FALSE,
           context = NULL) {
    if (length(query) > 1 || length(vc) > 1) {
      grid <- if (expand) expand_grid(query = query, vc = vc) else tibble(query = query, vc = vc)

      # Initialize timing variables for ETA calculation
      total_queries <- nrow(grid)
      current_query <- 0
      start_time <- Sys.time()

      results <- purrr::pmap(grid, function(query, vc, ...) {
        current_query <<- current_query + 1

        # Execute the single query directly (avoiding recursive call)
        contentFields <- c("snippet", "tokens")
        query_fields <- fields
        if (metadataOnly) {
          query_fields <- query_fields[!query_fields %in% contentFields]
        }
        if (!"textSigle" %in% query_fields) {
          query_fields <- c(query_fields, "textSigle")
        }
        request <-
          paste0(
            "?q=",
            url_encode(enc2utf8(query)),
            ifelse(!metadataOnly && !is.null(context) && context != "", paste0("&context=", url_encode(enc2utf8(context))), ""),
            ifelse(vc != "", paste0("&cq=", url_encode(enc2utf8(vc))), ""),
            ifelse(!metadataOnly, "&show-tokens=true", ""),
            "&ql=", ql
          )
        webUIRequestUrl <- paste0(kco@KorAPUrl, request)
        requestUrl <- paste0(
          kco@apiUrl,
          "search",
          request,
          "&fields=",
          paste(query_fields, collapse = ","),
          if (metadataOnly) "&access-rewrite-disabled=true" else ""
        )

        # Show individual query progress
        log_info(verbose, "\rSearching \"", query, "\" in \"", vc, "\"", sep = "")
        res <- apiCall(kco, paste0(requestUrl, "&count=0"))
        if (is.null(res)) {
          log_info(verbose, ": API call failed\n")
          totalResults <- 0
        } else {
          totalResults <- as.integer(res$meta$totalResults)
          log_info(verbose, ": ", totalResults, " hits")
          if (!is.null(res$meta$cached)) {
            log_info(verbose, " [cached]")
          } else if (!is.null(res$meta$benchmark)) {
            if (is.character(res$meta$benchmark) && grepl("s$", res$meta$benchmark)) {
              time_value <- as.numeric(sub("s$", "", res$meta$benchmark))
              formatted_time <- paste0(round(time_value, 2), "s")
              log_info(verbose, ", took ", formatted_time)
            } else {
              log_info(verbose, ", took ", res$meta$benchmark)
            }
          }
          log_info(verbose, "\n")
        }

        result <- data.frame(
          query = query,
          totalResults = totalResults,
          vc = vc,
          webUIRequestUrl = webUIRequestUrl,
          stringsAsFactors = FALSE
        )

        # Calculate and display ETA information if verbose and we have more than one query
        if (verbose && total_queries > 1) {
          eta_info <- calculate_eta(current_query, total_queries, start_time)
          if (eta_info != "") {
            elapsed_time <- as.numeric(difftime(Sys.time(), start_time, units = "secs"))
            avg_time_per_query <- elapsed_time / current_query

            # Create progress display
            progress_display <- paste0(
              "Query ",
              sprintf(paste0("%", nchar(total_queries), "d"), current_query),
              "/",
              sprintf("%d", total_queries),
              " completed. Avg: ",
              sprintf("%.1f", avg_time_per_query),
              "s/query",
              eta_info
            )

            log_info(verbose, progress_display, "\n")
          }
        }

        return(result)
      })

      results %>% bind_rows()
    } else {
      contentFields <- c("snippet", "tokens")
      if (metadataOnly) {
        fields <- fields[!fields %in% contentFields]
      }
      if (!"textSigle" %in% fields) {
        fields <- c(fields, "textSigle")
      }
      request <-
        paste0(
          "?q=",
          url_encode(enc2utf8(query)),
          ifelse(!metadataOnly && !is.null(context) && context != "", paste0("&context=", url_encode(enc2utf8(context))), ""),
          ifelse(vc != "", paste0("&cq=", url_encode(enc2utf8(vc))), ""),
          ifelse(!metadataOnly, "&show-tokens=true", ""),
          "&ql=", ql
        )
      webUIRequestUrl <- paste0(kco@KorAPUrl, request)
      requestUrl <- paste0(
        kco@apiUrl,
        "search",
        request,
        "&fields=",
        paste(fields, collapse = ","),
        if (metadataOnly) "&access-rewrite-disabled=true" else ""
      )
      log_info(verbose, "\rSearching \"", query, "\" in \"", vc, "\"",
        sep =
          ""
      )
      res <- apiCall(kco, paste0(requestUrl, "&count=0"))
      if (is.null(res)) {
        message("API call failed.")
        totalResults <- 0
      } else {
        totalResults <- as.integer(res$meta$totalResults)
        log_info(verbose, ": ", totalResults, " hits")
        if (!is.null(res$meta$cached)) {
          log_info(verbose, " [cached]\n")
        } else if (!is.null(res$meta$benchmark)) {
          # Round the benchmark time to 2 decimal places for better readability
          # If it's a string ending with 's', extract the number, round it, and re-add 's'
          if (is.character(res$meta$benchmark) && grepl("s$", res$meta$benchmark)) {
            time_value <- as.numeric(sub("s$", "", res$meta$benchmark))
            formatted_time <- paste0(round(time_value, 2), "s")
            log_info(verbose, ", took ", formatted_time, "\n", sep = "")
          } else {
            # Fallback if the format is different than expected
            log_info(verbose, ", took ", res$meta$benchmark, "\n", sep = "")
          }
        } else {
          log_info(verbose, "\n")
        }
      }
      if (as.df) {
        data.frame(
          query = query,
          totalResults = totalResults,
          vc = vc,
          webUIRequestUrl = webUIRequestUrl,
          stringsAsFactors = FALSE
        )
      } else {
        KorAPQuery(
          korapConnection = kco,
          nextStartIndex = 0,
          fields = fields,
          requestUrl = requestUrl,
          request = request,
          totalResults = totalResults,
          vc = vc,
          apiResponse = res,
          webUIRequestUrl = webUIRequestUrl,
          hasMoreMatches = (totalResults > 0),
        )
      }
    }
  }
)

#' @importFrom purrr map
repair_data_strcuture <- function(x) {
  if (is.list(x)) {
    as.character(purrr::map(x, ~ if (length(.x) > 1) {
      paste(.x, collapse = " ")
    } else {
      .x
    }))
  } else {
    ifelse(is.na(x), "", x)
  }
}

#' Fetch the next bunch of results of a KorAP query.
#'
#' **`fetchNext`** fetches the next bunch of results of a KorAP query.
#'
#' @param kqo object obtained from [corpusQuery()]
#' @param offset start offset for query results to fetch
#' @param maxFetch maximum number of query results to fetch
#' @param verbose print progress information if true
#' @param randomizePageOrder fetch result pages in pseudo random order if true. Use [set.seed()] to set seed for reproducible results.
#' @return The `kqo` input object with updated slots `collectedMatches`, `apiResponse`, `nextStartIndex`, `hasMoreMatches`
#'
#' @examples
#' \dontrun{
#'
#' q <- KorAPConnection() %>%
#'   corpusQuery("Ameisenplage") %>%
#'   fetchNext()
#' q@collectedMatches
#' }
#'
#' @references
#' <https://ids-pub.bsz-bw.de/frontdoor/index/index/docId/9026>
#'
#' @aliases fetchNext
#' @rdname KorAPQuery-class
#' @importFrom dplyr rowwise mutate bind_rows select summarise n select
#' @importFrom tibble enframe add_column
#' @importFrom stringr word
#' @importFrom tidyr unnest unchop pivot_wider
#' @importFrom purrr map
#' @export
setMethod("fetchNext", "KorAPQuery", function(kqo,
                                              offset = kqo@nextStartIndex,
                                              maxFetch = maxResultsPerPage,
                                              verbose = kqo@korapConnection@verbose,
                                              randomizePageOrder = FALSE) {
  # https://stackoverflow.com/questions/8096313/no-visible-binding-for-global-variable-note-in-r-cmd-check
  results <- key <- name <- tmp_positions <- 0

  if (kqo@totalResults == 0 || offset >= kqo@totalResults) {
    return(kqo)
  }
  use_korap_api <- Sys.getenv("USE_KORAP_API", unset = NA)
  # Calculate the initial page number (not used directly - keeping for reference)
  collectedMatches <- kqo@collectedMatches

  # For randomized page order, generate a list of randomized page indices
  if (randomizePageOrder) {
    # Calculate how many pages we need to fetch based on maxFetch
    total_pages_to_fetch <- if (!is.na(maxFetch)) {
      # Either limited by maxFetch or total results, whichever is smaller
      min(ceiling(maxFetch / maxResultsPerPage), ceiling(kqo@totalResults / maxResultsPerPage))
    } else {
      # All pages
      ceiling(kqo@totalResults / maxResultsPerPage)
    }

    # Generate randomized page indices (0-based for API)
    pages <- sample.int(ceiling(kqo@totalResults / maxResultsPerPage), total_pages_to_fetch) - 1
    page_index <- 1 # Index to track which page in the randomized list we're on
  }

  if (is.null(collectedMatches)) {
    collectedMatches <- data.frame()
  }

  # Initialize the page counter properly based on nextStartIndex and any previously fetched results
  # We add 1 to make it 1-based for display purposes since users expect page numbers to start from 1
  # For first call, this will be 1, for subsequent calls, it will reflect our actual position
  current_page_number <- ceiling(offset / maxResultsPerPage) + 1

  # For sequential fetches, keep track of which global page we're on
  # This is important for correctly showing page numbers in subsequent fetchNext calls
  page_count_start <- current_page_number

  repeat {
    # Determine which page to fetch next
    if (randomizePageOrder) {
      # In randomized mode, get the page from our randomized list using the page_index
      # Make sure we don't exceed the array bounds
      if (page_index > length(pages)) {
        break # No more pages to fetch in randomized mode
      }
      current_offset_page <- pages[page_index]
      # For display purposes in randomized mode, show which page out of the total we're fetching
      display_page_number <- page_index
    } else {
      # In sequential mode, use the current_page_number to calculate the offset
      current_offset_page <- (current_page_number - 1)
      display_page_number <- current_page_number
    }

    # Calculate the actual offset in tokens
    currentOffset <- current_offset_page * maxResultsPerPage

    # Build the query with the appropriate count and offset using httr2
    count_param <- min(if (!is.na(maxFetch)) maxFetch - results else maxResultsPerPage, maxResultsPerPage)
    
    # Parse existing URL to preserve all query parameters
    parsed_url <- httr2::url_parse(kqo@requestUrl)
    existing_query <- parsed_url$query
    
    # Add/update count and offset parameters
    existing_query$count <- count_param
    existing_query$offset <- currentOffset
    
    # Rebuild the URL with all parameters
    query <- httr2::url_modify(kqo@requestUrl, query = existing_query)
    res <- apiCall(kqo@korapConnection, query)
    if (length(res$matches) == 0) {
      break
    }

    if ("fields" %in% colnames(res$matches) && (is.na(use_korap_api) || as.numeric(use_korap_api) >= 1.0)) {
      log_info(verbose, "Using fields API: ")
      currentMatches <- res$matches$fields %>%
        purrr::map(~ mutate(.x, value = repair_data_strcuture(value))) %>%
        tibble::enframe() %>%
        tidyr::unnest(cols = value) %>%
        tidyr::pivot_wider(names_from = key, id_cols = name, names_repair = "unique") %>%
        dplyr::select(-name)
      if ("snippet" %in% colnames(res$matches)) {
        currentMatches$snippet <- res$matches$snippet
      }
      if ("tokens" %in% colnames(res$matches)) {
        currentMatches$tokens <- res$matches$tokens
      }
    } else {
      currentMatches <- res$matches
    }

    for (field in kqo@fields) {
      if (!field %in% colnames(currentMatches)) {
        currentMatches[, field] <- NA
      }
    }
    currentMatches <- currentMatches %>%
      select(kqo@fields) %>%
      mutate(
        tmp_positions = gsub(".*-p(\\d+)-(\\d+).*", "\\1 \\2", res$matches$matchID),
        matchStart = as.integer(stringr::word(tmp_positions, 1)),
        matchEnd = as.integer(stringr::word(tmp_positions, 2)) - 1
      ) %>%
      select(-tmp_positions)

    if (!is.list(collectedMatches)) {
      collectedMatches <- currentMatches
    } else {
      collectedMatches <- bind_rows(collectedMatches, currentMatches)
    }

    # Get the actual items per page from the API response
    # We now consistently use maxResultsPerPage instead

    # Calculate total pages consistently using fixed maxResultsPerPage
    # This ensures consistent page counting across the function
    total_pages <- ceiling(kqo@totalResults / maxResultsPerPage)

    # Calculate the total pages based on what we've already fetched plus what we'll fetch
    # This ensures the correct denominator is displayed for subsequent fetchNext calls

    # Calculate the total number of pages for the entire result set
    # This calculation is kept for reference and for showing in parentheses

    # Estimate remaining time
    time_per_page <- NA
    eta_str <- "N/A"
    completion_time_str <- "N/A"

    if (!is.null(res$meta$benchmark) && is.character(res$meta$benchmark)) {
      # benchmark looks like "0.123s"
      time_per_page <- suppressWarnings(as.numeric(sub("s", "", res$meta$benchmark)))
      if (!is.na(time_per_page)) {
        # Calculate remaining pages based on what we still need to fetch
        if (!is.na(maxFetch)) {
          # Use the same logic as page display calculation - account for offset
          remaining_results_after_offset <- max(0, kqo@totalResults - offset)
          total_pages_this_batch <- min(ceiling(maxFetch / maxResultsPerPage), ceiling(remaining_results_after_offset / maxResultsPerPage))
          current_page_in_batch <- ceiling(nrow(collectedMatches) / maxResultsPerPage) + 1
          remaining_pages <- max(0, total_pages_this_batch - current_page_in_batch)
        } else {
          # We need to fetch all results - calculate based on actual position
          if (randomizePageOrder) {
            if (exists("pages") && length(pages) > 0) {
              remaining_pages <- max(0, length(pages) - page_index)
            } else {
              # Fallback to a reasonable default
              remaining_pages <- 1
            }
          } else {
            # For sequential order, calculate remaining pages from current offset
            current_absolute_page <- ceiling((currentOffset + maxResultsPerPage) / maxResultsPerPage)
            remaining_pages <- max(0, total_pages - current_absolute_page)
          }
        }

        estimated_remaining_seconds <- remaining_pages * time_per_page
        estimated_completion_time <- Sys.time() + estimated_remaining_seconds

        # Format time nicely using centralized function from logging.R

        eta_str <- format_duration(estimated_remaining_seconds)
        completion_time_str <- format(estimated_completion_time, "%Y-%m-%d %H:%M:%S")
      }
    }

    # Create the page display string with proper formatting

    # For global page tracking, calculate the absolute page number
    actual_display_number <- if (randomizePageOrder) {
      current_offset_page + 1 # In randomized mode, this is the actual page (0-based + 1)
    } else {
      # In sequential mode, the absolute page number is the actual offset page + 1 (to make it 1-based)
      current_offset_page + 1
    }

    # For subsequent calls to fetchNext, we need to calculate the correct page numbers
    # based on the current batch being fetched

    # For each call to fetchNext, we want to show 1/2, 2/2 (not 3/4, 4/4)
    # Simply count from 1 within the current batch

    # The relative page number is simply the current position in this batch
    if (randomizePageOrder) {
      relative_page_number <- page_index # In randomized mode, we start from 1 in each batch
    } else {
      relative_page_number <- display_page_number - (page_count_start - 1)
    }

    # How many pages will we fetch in this batch?
    # If maxFetch is specified, calculate the total pages for this fetch operation
    pages_in_this_batch <- if (!is.na(maxFetch)) {
      # Account for offset - we can only fetch from the remaining results after offset
      remaining_results_after_offset <- max(0, kqo@totalResults - offset)
      min(ceiling(maxFetch / maxResultsPerPage), ceiling(remaining_results_after_offset / maxResultsPerPage))
    } else {
      # Otherwise fetch all remaining pages
      total_pages - page_count_start + 1
    }

    # The total pages to be shown in this batch
    batch_total_pages <- pages_in_this_batch

    page_display <- paste0(
      "Retrieved page ",
      sprintf(paste0("%", nchar(batch_total_pages), "d"), relative_page_number),
      "/",
      sprintf("%d", batch_total_pages)
    )

    # If randomized, also show which actual page we fetched
    if (randomizePageOrder) {
      # Determine the maximum width needed for page numbers (based on total pages)
      # This ensures consistent alignment
      max_page_width <- nchar(as.character(total_pages))
      # Add the actual page number that was fetched (0-based + 1 for display) with proper padding
      page_display <- paste0(
        page_display,
        sprintf(" (actual page %*d)", max_page_width, current_offset_page + 1)
      )
    }
    # Always show the absolute page number and total pages (for clarity)
    else {
      # Show the absolute page number (out of total possible pages)
      page_display <- paste0(page_display, sprintf(
        " (page %d of %d total)",
        actual_display_number, total_pages
      ))
    }

    # Add caching or timing information
    if (!is.null(res$meta$cached)) {
      page_display <- paste0(page_display, " [cached]")
    } else {
      page_display <- paste0(
        page_display,
        " in ",
        if (!is.na(time_per_page)) sprintf("%4.1f", time_per_page) else "?",
        "s. ETA: ",
        # Display ETA for both randomized and sequential modes
        eta_str,
        # Show completion time for both modes
        paste0(" (", completion_time_str, ")")
      )
    }

    log_info(verbose, paste0(page_display, "\n"))

    # Increment the appropriate counter based on mode
    if (randomizePageOrder) {
      page_index <- page_index + 1
    } else {
      current_page_number <- current_page_number + 1
    }
    results <- results + res$meta$itemsPerPage
    if (nrow(collectedMatches) >= kqo@totalResults || (!is.na(maxFetch) && results >= maxFetch)) {
      break
    }
  }
  nextStartIndex <- min(res$meta$startIndex + res$meta$itemsPerPage, kqo@totalResults)
  KorAPQuery(
    nextStartIndex = nextStartIndex,
    korapConnection = kqo@korapConnection,
    fields = kqo@fields,
    requestUrl = kqo@requestUrl,
    request = kqo@request,
    totalResults = kqo@totalResults,
    vc = kqo@vc,
    webUIRequestUrl = kqo@webUIRequestUrl,
    hasMoreMatches = (kqo@totalResults > nextStartIndex),
    apiResponse = res,
    collectedMatches = collectedMatches
  )
})

#' Fetch all results of a KorAP query.
#'
#' **`fetchAll`** fetches all results of a KorAP query.
#'
#' @examples
#' \dontrun{
#'
#' q <- KorAPConnection() %>%
#'   corpusQuery("Ameisenplage") %>%
#'   fetchAll()
#' q@collectedMatches
#' }
#'
#' @aliases fetchAll
#' @rdname KorAPQuery-class
#' @export
setMethod("fetchAll", "KorAPQuery", function(kqo, verbose = kqo@korapConnection@verbose, ...) {
  return(fetchNext(kqo, offset = 0, maxFetch = NA, verbose = verbose, ...))
})

#' Fetches the remaining results of a KorAP query.
#'
#' @examples
#' \dontrun{
#'
#' q <- KorAPConnection() %>%
#'   corpusQuery("Ameisenplage") %>%
#'   fetchRest()
#' q@collectedMatches
#' }
#'
#' @aliases fetchRest
#' @rdname KorAPQuery-class
#' @export
setMethod("fetchRest", "KorAPQuery", function(kqo, verbose = kqo@korapConnection@verbose, ...) {
  return(fetchNext(kqo, maxFetch = NA, verbose = verbose, ...))
})

#' Query frequencies of search expressions in virtual corpora
#'
#' **`frequencyQuery`** combines [corpusQuery()], [corpusStats()] and
#' [ci()] to compute a tibble with the absolute and relative frequencies and
#' confidence intervals of one ore multiple search terms across one or multiple
#' virtual corpora.
#'
#' @aliases frequencyQuery
#' @examples
#' \dontrun{
#'
#' KorAPConnection(verbose = TRUE) |>
#'   frequencyQuery(c("Mücke", "Schnake"), paste0("pubDate in ", 2000:2003))
#' }
#'
# @inheritParams corpusQuery
#' @param kco [KorAPConnection()] object (obtained e.g. from `KorAPConnection()`
#' @param query corpus query string(s.) (can be a vector). The query language depends on the `ql` parameter. Either `query` must be provided or `KorAPUrl`.
#' @param vc virtual corpus definition(s) (can be a vector)
#' @param conf.level confidence level of the returned confidence interval (passed through [ci()]  to [prop.test()]).
#' @param as.alternatives LOGICAL that specifies if the query terms should be treated as alternatives. If `as.alternatives` is TRUE, the sum over all query hits, instead of the respective vc token sizes is used as total for the calculation of relative frequencies.
#' @param ... further arguments passed to or from other methods (see [corpusQuery()]), most notably `expand`, a logical that decides if `query` and `vc` parameters are expanded to all of their combinations. It defaults to `TRUE`, if `query` and `vc` have different lengths, and to `FALSE` otherwise.
#' @export
#'
#' @return A tibble, with each row containing the following result columns for query and vc combinations:
#'   - **query**: the query string used for the frequency analysis.
#'   - **totalResults**: absolute frequency of query matches in the vc.
#'   - **vc**:  virtual corpus used for the query.
#'   - **webUIRequestUrl**: URL of the corresponding web UI request with respect to query and vc.
#'   - **total**: total number of words in vc.
#'   - **f**:  relative frequency of query matches in the vc.
#'   - **conf.low**:  lower bound of the confidence interval for the relative frequency, given `conf.level`.
#'   - **conf.high**:  upper bound of the confidence interval for the relative frequency, given `conf.level`.

setMethod(
  "frequencyQuery", "KorAPConnection",
  function(kco, query, vc = "", conf.level = 0.95, as.alternatives = FALSE, ...) {
    (if (as.alternatives) {
      corpusQuery(kco, query, vc, metadataOnly = TRUE, as.df = TRUE, ...) |>
        group_by(vc) %>%
        mutate(total = sum(totalResults))
    } else {
      corpusQuery(kco, query, vc, metadataOnly = TRUE, as.df = TRUE, ...) |>
        mutate(total = corpusStats(kco, vc = vc, as.df = TRUE)$tokens)
    }) %>%
      ci(conf.level = conf.level)
  }
)

#' buildWebUIRequestUrlFromString
#'
#' @rdname KorAPQuery-class
#' @importFrom urltools url_encode
#' @export
buildWebUIRequestUrlFromString <- function(KorAPUrl,
                                           query,
                                           vc = "",
                                           ql = "poliqarp") {
  if ("KorAPConnection" %in% class(KorAPUrl)) {
    KorAPUrl <- KorAPUrl@KorAPUrl
  }

  request <-
    paste0(
      "?q=",
      urltools::url_encode(enc2utf8(as.character(query))),
      ifelse(vc != "",
        paste0("&cq=", urltools::url_encode(enc2utf8(vc))),
        ""
      ),
      "&ql=",
      ql
    )
  paste0(KorAPUrl, request)
}

#' buildWebUIRequestUrl
#'
#' @rdname KorAPQuery-class
#' @importFrom httr2 url_parse
#' @export
buildWebUIRequestUrl <- function(kco,
                                 query = if (missing(KorAPUrl)) {
                                   stop("At least one of the parameters query and KorAPUrl must be specified.", call. = FALSE)
                                 } else {
                                   httr2::url_parse(KorAPUrl)$query$q
                                 },
                                 vc = if (missing(KorAPUrl)) "" else httr2::url_parse(KorAPUrl)$query$cq,
                                 KorAPUrl,
                                 ql = if (missing(KorAPUrl)) "poliqarp" else httr2::url_parse(KorAPUrl)$query$ql) {
  buildWebUIRequestUrlFromString(kco@KorAPUrl, query, vc, ql)
}

#' format()
#' @rdname KorAPQuery-class
#' @param x KorAPQuery object
#' @param ... further arguments passed to or from other methods
#' @importFrom urltools param_get url_decode
#' @export
format.KorAPQuery <- function(x, ...) {
  cat("<KorAPQuery>\n")
  q <- x
  param <- urltools::param_get(q@request) |> lapply(urltools::url_decode)
  cat("           Query: ", param$q, "\n")
  if (!is.null(param$cq) && param$cq != "") {
    cat("  Virtual corpus: ", param$cq, "\n")
  }
  if (!is.null(q@collectedMatches)) {
    cat("==============================================================================================================", "\n")
    print(summary(q@collectedMatches))
    cat("==============================================================================================================", "\n")
  }
  cat("   Total results: ", q@totalResults, "\n")
  cat(" Fetched results: ", q@nextStartIndex, "\n")
}

#' show()
#'
#' @rdname KorAPQuery-class
#' @param object KorAPQuery object
#' @export
setMethod("show", "KorAPQuery", function(object) {
  format(object)
})