module SunbusStopSearch

# File lib/sunbus/stop_search.rb, line 40
def distance_km(lat1, lon1, lat2, lon2)
  radius = 6371.0
  dlat = (lat2 - lat1) * Math::PI / 180
  dlon = (lon2 - lon1) * Math::PI / 180
  lat1_rad = lat1 * Math::PI / 180
  lat2_rad = lat2 * Math::PI / 180
  a = Math.sin(dlat / 2)**2 + Math.cos(lat1_rad) * Math.cos(lat2_rad) * Math.sin(dlon / 2)**2
  2 * radius * Math.asin(Math.sqrt(a))
end

# File lib/sunbus/stop_search.rb, line 36
def expand_tokens(tokens)
  tokens.flat_map { |token| ABBREVIATIONS[token] ? [token, ABBREVIATIONS[token]] : [token] }
end

# File lib/sunbus/stop_search.rb, line 116
def merge_unique(first, second, limit:)
  seen = Set.new
  merged = []
  (first + second).each do |stop|
    key = stop[:stop_id]
    next if seen.include?(key)

    seen.add(key)
    merged << stop
    break if merged.length >= limit
  end
  merged
end

# File lib/sunbus/stop_search.rb, line 62
def name_score(stop, query)
  name = normalize_text(stop[:name])
  needle = normalize_text(query)
  return nil if needle.empty?

  if numeric_query?(query)
    code = stop[:stop_code].to_s
    id = stop[:stop_id].to_s
    return 0 if code == needle || id == needle
    return 1 if code.end_with?(needle) || id.end_with?(needle)

    return nil
  end

  return 0 if name == needle
  return 1 if name.start_with?(needle)
  return 2 if name.include?(needle)

  tokens = expand_tokens(query_tokens(query))
  return nil if tokens.empty?

  return 3 if tokens.all? { |token| name.include?(token) }

  nil
end

# File lib/sunbus/stop_search.rb, line 24
def normalize_text(text)
  text.to_s.downcase
      .gsub(/['']/, "")
      .gsub(/[^a-z0-9\s]/, " ")
      .squeeze(" ")
      .strip
end

# File lib/sunbus/stop_search.rb, line 58
def numeric_query?(query)
  query.to_s.strip.match?(/\A\d+\z/)
end

# File lib/sunbus/stop_search.rb, line 32
def query_tokens(query)
  normalize_text(query).split.reject { |token| token.length < 2 || STOP_WORDS.include?(token) }
end

# File lib/sunbus/stop_search.rb, line 98
def rank_by_name(stops, query)
  stops.filter_map do |stop|
    score = name_score(stop, query)
    next unless score

    [score, stop]
  end.sort_by { |score, _| score }.map(&:last)
end

# File lib/sunbus/stop_search.rb, line 107
def rank_by_suburb(stops, suburb)
  stops.filter_map do |stop|
    distance = suburb_geo_score(stop, suburb)
    next unless distance

    [distance, stop]
  end.sort_by { |distance, _| distance }.map(&:last)
end

# File lib/sunbus/stop_search.rb, line 130
def search(stops, query, region: SunbusConfig::DEFAULT_REGION, limit: SunbusConfig::MAX_STOPS)
  SunbusAliases.variants(query).each do |variant|
    matches = search_variants(stops, variant, region: region, limit: limit)
    return matches unless matches.empty?
  end

  []
end

# File lib/sunbus/stop_search.rb, line 139
def search_variants(stops, query, region:, limit:)
  needle = query.to_s.strip
  return [] if needle.empty?

  name_ranked = rank_by_name(stops, needle)
  suburb = SunbusSuburbs.resolve(needle, region: region)
  if suburb
    geo_ranked = rank_by_suburb(stops, suburb)
    return merge_unique(name_ranked, geo_ranked, limit: limit)
  end

  name_ranked.first(limit)
end

# File lib/sunbus/stop_search.rb, line 50
def stop_lat_lon(stop)
  lat = stop[:lat]
  lon = stop[:lon]
  return nil unless lat && lon

  [lat.to_f, lon.to_f]
end

# File lib/sunbus/stop_search.rb, line 88
def suburb_geo_score(stop, suburb)
  coords = stop_lat_lon(stop)
  return nil unless coords

  distance = distance_km(suburb[:lat], suburb[:lon], coords[0], coords[1])
  return nil if distance > suburb[:radius_km]

  distance
end