dawarich/app/services/stats/hexagon_calculator.rb
2025-09-29 22:27:07 +02:00

113 lines
3.4 KiB
Ruby

# frozen_string_literal: true
class Stats::HexagonCalculator
# H3 Configuration
DEFAULT_H3_RESOLUTION = 8 # Small hexagons for good detail
MAX_HEXAGONS = 10_000 # Maximum number of hexagons to prevent memory issues
class PostGISError < StandardError; end
def initialize(user_id, year, month)
@user = User.find(user_id)
@year = year.to_i
@month = month.to_i
end
def call(h3_resolution: DEFAULT_H3_RESOLUTION)
calculate_h3_hexagon_centers(h3_resolution)
end
private
attr_reader :user, :year, :month
def calculate_h3_hexagon_centers(h3_resolution)
result = calculate_hexagons(h3_resolution)
return [] if result.nil?
# Convert to array format: [h3_index_string, point_count, earliest_timestamp, latest_timestamp]
result.map do |h3_index_string, data|
[
h3_index_string,
data[0], # count
data[1], # earliest
data[2] # latest
]
end
end
# Unified hexagon calculation method
def calculate_hexagons(h3_resolution)
return nil if points.empty?
begin
h3_hash = calculate_h3_indexes(points, h3_resolution)
if h3_hash.empty?
Rails.logger.info "No H3 hex IDs calculated for user #{user.id}, #{year}-#{month} (no data)"
return nil
end
if h3_hash.size > MAX_HEXAGONS
Rails.logger.warn "Too many hexagons (#{h3_hash.size}), using lower resolution"
# Try with lower resolution (larger hexagons)
lower_resolution = [h3_resolution - 2, 0].max
Rails.logger.info "Recalculating with lower H3 resolution: #{lower_resolution}"
# Create a new instance with lower resolution for recursion
return self.class.new(user.id, year, month).calculate_hexagons(lower_resolution)
end
Rails.logger.info "Generated #{h3_hash.size} H3 hexagons at resolution #{h3_resolution} for user #{user.id}"
h3_hash
rescue StandardError => e
message = "Failed to calculate H3 hexagon centers: #{e.message}"
ExceptionReporter.call(e, message) if defined?(ExceptionReporter)
raise PostGISError, message
end
end
def start_timestamp
DateTime.new(year, month, 1).to_i
end
def end_timestamp
DateTime.new(year, month, -1).to_i # -1 returns last day of month
end
def points
return @points if defined?(@points)
@points = user
.points
.without_raw_data
.where(timestamp: start_timestamp..end_timestamp)
.where.not(lonlat: nil)
.select(:lonlat, :timestamp)
.order(timestamp: :asc)
end
def calculate_h3_indexes(points, h3_resolution)
h3_data = {}
points.find_each do |point|
# Extract lat/lng from PostGIS point
coordinates = [point.lonlat.y, point.lonlat.x] # [lat, lng] for H3
# Get H3 index for this point
h3_index = H3.from_geo_coordinates(coordinates, h3_resolution.clamp(0, 15))
h3_index_string = h3_index.to_s(16) # Convert to hex string immediately
# Initialize or update data for this hexagon
if h3_data[h3_index_string]
data = h3_data[h3_index_string]
data[0] += 1 # increment count
data[1] = [data[1], point.timestamp].min # update earliest
data[2] = [data[2], point.timestamp].max # update latest
else
h3_data[h3_index_string] = [1, point.timestamp, point.timestamp] # [count, earliest, latest]
end
end
h3_data
end
end