scripts/export_seo_metadata.R

# scripts/export_seo_metadata.R
#
# Exports enriched DWD station metadata from all 5 resolution caches
# into a single JSON file for use by the Netlify Edge Function.
#
# Output: dwd-seo-metadata.json
#
# Usage:
#   Rscript scripts/export_seo_metadata.R
#   (run from the DWD app root directory)

# Ensure UTF-8 output
invisible(Sys.setlocale("LC_CTYPE", "en_US.UTF-8"))

library(jsonlite)

# ── Slugification ────────────────────────────────────────────────────────

slugify <- function(text) {
    s <- as.character(text)

    # German umlaut / special char replacements (before NFD decomposition)
    s <- gsub("\u00fc", "ue", s) # ü
    s <- gsub("\u00f6", "oe", s) # ö
    s <- gsub("\u00e4", "ae", s) # ä
    s <- gsub("\u00dc", "Ue", s) # Ü
    s <- gsub("\u00d6", "Oe", s) # Ö
    s <- gsub("\u00c4", "Ae", s) # Ä
    s <- gsub("\u00df", "ss", s) # ß

    # Lowercase
    s <- tolower(s)

    # Remove accents via iconv transliteration
    s <- iconv(s, from = "UTF-8", to = "ASCII//TRANSLIT", sub = "")

    # Replace non-alphanumeric with hyphens
    s <- gsub("[^a-z0-9]+", "-", s)

    # Trim leading/trailing hyphens
    s <- gsub("^-+|-+$", "", s)

    s
}

# ── Resolution config ────────────────────────────────────────────────────

resolution_config <- list(
    list(
        key       = "daily",
        label     = "Daily",
        slug      = "daily",
        file      = "www/tabs/dwd_stations_enriched_daily.rds"
    ),
    list(
        key       = "hourly",
        label     = "Hourly",
        slug      = "hourly",
        file      = "www/tabs/dwd_stations_enriched.rds"
    ),
    list(
        key       = "monthly",
        label     = "Monthly",
        slug      = "monthly",
        file      = "www/tabs/dwd_stations_enriched_monthly.rds"
    ),
    list(
        key       = "annual",
        label     = "Annual",
        slug      = "annual",
        file      = "www/tabs/dwd_stations_enriched_annual.rds"
    ),
    list(
        key       = "10_minutes",
        label     = "10 Minutes",
        slug      = "10-minutes",
        file      = "www/tabs/dwd_stations_enriched_10min.rds"
    )
)

# ── Main export ──────────────────────────────────────────────────────────

stations_out   <- list()
states_out     <- list()
resolutions_out <- list()
slug_map       <- list()

for (rc in resolution_config) {
    if (!file.exists(rc$file)) {
        message("Skipping ", rc$key, ": file not found (", rc$file, ")")
        next
    }

    df <- readRDS(rc$file)
    message(rc$label, ": ", nrow(df), " stations loaded")

    res_slug <- rc$slug

    # ── Per-state aggregation ────────────────────────────────────────────
    state_counts <- list()

    for (i in seq_len(nrow(df))) {
        row <- df[i, ]

        station_name   <- enc2utf8(as.character(row$name))
        station_id     <- as.character(row$id)
        state_name     <- enc2utf8(as.character(row$state))
        station_slug   <- slugify(station_name)
        state_slug     <- slugify(state_name)

        # Build path key: "daily/bayern/muenchen-flughafen"
        path_key <- paste0(res_slug, "/", state_slug, "/", station_slug)

        # Station entry
        entry <- list(
            id              = station_id,
            name            = station_name,
            state           = state_name,
            stateSlug       = state_slug,
            elevation       = as.numeric(row$elevation),
            lat             = as.numeric(row$latitude),
            lon             = as.numeric(row$longitude),
            resolution      = rc$key,
            resolutionLabel = rc$label,
            resolutionSlug  = res_slug,
            overallStart    = as.character(row$station_overall_start),
            overallEnd      = as.character(row$station_overall_end)
        )

        # Add detailed_summary if available
        if ("detailed_summary" %in% names(row)) {
            entry$availableParams <- as.character(row$detailed_summary)
        }

        stations_out[[path_key]] <- entry

        # Track state counts
        state_key <- paste0(res_slug, "/", state_slug)
        if (is.null(state_counts[[state_key]])) {
            state_counts[[state_key]] <- list(
                state           = state_name,
                stateSlug       = state_slug,
                resolution      = rc$key,
                resolutionLabel = rc$label,
                resolutionSlug  = res_slug,
                stationCount    = 0L,
                activeStationCount = 0L
            )
        }
        state_counts[[state_key]]$stationCount <-
            state_counts[[state_key]]$stationCount + 1L
            
        # Determine the UI's default date range start for this resolution
        # Must match server.R URL param handler for initial load
        default_start_date <- switch(rc$key,
            "10_minutes" = Sys.Date() - 30,
            "hourly"     = Sys.Date() - 366,
            "monthly"    = Sys.Date() - (365 * 6),
            "daily"      = Sys.Date() - (365 * 6),
            "annual"     = as.Date("1991-01-01"),
            Sys.Date() - (365 * 6)
        )
        default_start_num <- as.numeric(format(default_start_date, "%Y%m%d"))
        default_end_num <- as.numeric(format(Sys.Date(), "%Y%m%d"))
        
        overall_start_str <- as.character(row$station_overall_start)
        overall_end_str <- as.character(row$station_overall_end)
        is_active <- FALSE
        
        # Must match server.R filtered_stations():
        # as.numeric(station_overall_start) <= range_end &
        # as.numeric(station_overall_end) >= range_start
        start_num <- suppressWarnings(as.numeric(overall_start_str))
        end_num <- if (overall_end_str == "99999999") Inf else suppressWarnings(as.numeric(overall_end_str))
        
        if (!is.na(start_num) && !is.na(end_num) &&
            start_num <= default_end_num && end_num >= default_start_num) {
            is_active <- TRUE
        }

        if (is_active) {
            state_counts[[state_key]]$activeStationCount <-
                state_counts[[state_key]]$activeStationCount + 1L
        }

        # Slug map (only need unique entries)
        if (is.null(slug_map[[station_name]])) {
            slug_map[[station_name]] <- station_slug
        }
        if (is.null(slug_map[[state_name]])) {
            slug_map[[state_name]] <- state_slug
        }
    }

    # Merge state entries
    for (sk in names(state_counts)) {
        states_out[[sk]] <- state_counts[[sk]]
    }

    # Resolution summary (including active count summed from states)
    total_active <- sum(sapply(state_counts, function(sc) sc$activeStationCount))
    resolutions_out[[res_slug]] <- list(
        key          = rc$key,
        label        = rc$label,
        slug         = res_slug,
        stationCount = nrow(df),
        activeStationCount = total_active
    )
}

# ── Assemble and write JSON ──────────────────────────────────────────────

output <- list(
    stations    = stations_out,
    states      = states_out,
    resolutions = resolutions_out,
    slugMap     = slug_map
)

output_path <- "dwd-seo-metadata.json"
json_str <- toJSON(output, pretty = TRUE, auto_unbox = TRUE)
writeLines(json_str, output_path)

message("\nExported ", length(stations_out), " station entries, ",
        length(states_out), " state entries, ",
        length(resolutions_out), " resolutions")
message("Output: ", normalizePath(output_path))