From 582e64c94b5f133d941a9b8dca0f1972dc49d392 Mon Sep 17 00:00:00 2001
From: Eugene Burmakin <iamfrey@gmail.com>
Date: Wed, 21 May 2025 18:51:39 +0200
Subject: [PATCH] Add transportation mode service

---
 app/services/transportation_mode_service.rb | 304 ++++++++++++++++++++
 1 file changed, 304 insertions(+)
 create mode 100644 app/services/transportation_mode_service.rb

diff --git a/app/services/transportation_mode_service.rb b/app/services/transportation_mode_service.rb
new file mode 100644
index 00000000..9da3a29c
--- /dev/null
+++ b/app/services/transportation_mode_service.rb
@@ -0,0 +1,304 @@
+# frozen_string_literal: true
+
+class TransportationModeService
+  MODES = {
+    walking: { min: 0, max: 7 },      # km/h
+    running: { min: 7, max: 25 },
+    bicycle: { min: 10, max: 45 },
+    motorbike: { min: 20, max: 150 },
+    car: { min: 20, max: 200 },       # car/taxi/bus
+    train: { min: 20, max: 300 },
+    boat: { min: 5, max: 80 },        # ferry/boat
+    plane: { min: 200, max: 1000 }
+  }
+
+  RESTRICTED_MODES = {
+    "highway" => [:walking, :running],
+    "railway" => [:walking, :running, :bicycle, :motorbike, :car, :boat],
+    "water" => [:walking, :running, :bicycle, :motorbike, :car, :train],
+    "aeroway" => [:walking, :running, :bicycle, :motorbike, :car, :train, :boat]
+  }
+
+  def initialize(points)
+    @points = points.sort_by(&:timestamp).reject { |p| p.velocity&.to_f&.negative? }
+    @points = calculate_missing_velocities(@points)
+  end
+
+  def analyze
+    return [] if @points.empty?
+
+    point_results = analyze_points
+    group_into_segments(point_results)
+  end
+
+  private
+
+  def analyze_points
+    results = []
+    previous_mode = nil
+    consecutive_same_mode_count = 0
+
+    @points.each_with_index do |point, index|
+      # Get initial mode based on speed
+      speed_km_h = point.velocity.to_f * 3.6 # Convert m/s to km/h
+      possible_modes = modes_by_speed(speed_km_h)
+
+      # Refine by geocoding data if available
+      favored_mode = nil
+      if point.reverse_geocoded?
+        restricted, favored_mode = restricted_modes_at_location(point)
+        possible_modes -= restricted if restricted.any?
+      end
+
+      # Consider road type priority if available
+      if favored_mode && possible_modes.include?(favored_mode)
+        chosen_mode = favored_mode
+      # Consider previous mode for consistency (avoid jumping)
+      elsif previous_mode && possible_modes.include?(previous_mode)
+        # Stick with previous mode if it's still possible
+        # Increase confidence as we get more consecutive points with same mode
+        chosen_mode = previous_mode
+        consecutive_same_mode_count += 1
+      elsif previous_mode && index > 0 && consecutive_same_mode_count < 3
+        # Try to avoid abrupt changes by preferring modes close to previous
+        # But only if we haven't established a strong pattern yet
+        prev_point = @points[index - 1]
+        prev_speed = prev_point.velocity.to_f * 3.6
+        chosen_mode = best_consistent_mode(possible_modes, previous_mode, speed_km_h, prev_speed)
+      else
+        # Pick most likely mode from possible ones
+        chosen_mode = most_likely_mode(possible_modes, speed_km_h)
+      end
+
+      # Reset counter if mode changes
+      if previous_mode != chosen_mode
+        consecutive_same_mode_count = 0
+      end
+
+      previous_mode = chosen_mode
+      results << { point: point, mode: chosen_mode }
+    end
+
+    # Post-processing: fix isolated mode changes (car-bicycle-car pattern)
+    smooth_isolated_mode_changes(results)
+  end
+
+  def group_into_segments(point_results)
+    segments = []
+    current_segment = nil
+
+    point_results.each do |result|
+      point = result[:point]
+      mode = result[:mode]
+      time = Time.zone.at(point.timestamp)
+      speed_km_h = point.velocity.to_f * 3.6 # Convert m/s to km/h
+
+      if current_segment.nil? || current_segment[:mode] != mode
+        # Close previous segment if exists
+        if current_segment
+          end_time = Time.zone.at(point_results[point_results.index(result) - 1][:point].timestamp)
+          current_segment[:ended_at] = end_time
+          current_segment[:minutes] = ((end_time - current_segment[:started_at]) / 60).round(1)
+        end
+
+        # Start new segment
+        current_segment = {
+          started_at: time,
+          ended_at: nil,
+          mode: mode,
+          minutes: nil,
+          speed_range: {
+            min: speed_km_h,
+            max: speed_km_h,
+            avg: speed_km_h
+          }
+        }
+        segments << current_segment
+      else
+        # Update speed range for current segment
+        current_segment[:speed_range][:min] = [current_segment[:speed_range][:min], speed_km_h].min
+        current_segment[:speed_range][:max] = [current_segment[:speed_range][:max], speed_km_h].max
+
+        # Update running average (simplified approach)
+        segment_points = point_results.select { |r| r[:mode] == mode &&
+                                              r[:point].timestamp >= current_segment[:started_at].to_i &&
+                                              r[:point].timestamp <= point.timestamp }
+        speeds = segment_points.map { |r| r[:point].velocity.to_f * 3.6 }
+        current_segment[:speed_range][:avg] = (speeds.sum / speeds.size).round(1) if speeds.any?
+      end
+    end
+
+    # Close the last segment
+    if current_segment && current_segment[:ended_at].nil?
+      last_point = point_results.last[:point]
+      end_time = Time.zone.at(last_point.timestamp)
+      current_segment[:ended_at] = end_time
+      current_segment[:minutes] = ((end_time - current_segment[:started_at]) / 60).round(1)
+    end
+
+    # Filter out segments with 0 duration
+    segments.reject { |segment| segment[:minutes] == 0 }
+  end
+
+  def calculate_missing_velocities(points)
+    points.each_with_index do |point, index|
+      next if point.velocity.present? && point.velocity.to_f >= 0
+
+      if index > 0
+        previous_point = points[index - 1]
+        time_diff = point.timestamp - previous_point.timestamp
+
+        # Skip if points have identical timestamps
+        if time_diff <= 0
+          point.velocity.to_f = 0
+          next
+        end
+
+        # Calculate distance between points in meters
+        distance = previous_point.distance_to(point) * 1000
+
+        # Calculate velocity in m/s
+        point.velocity&.to_f = distance / time_diff
+      else
+        # For the first point with nil velocity, look ahead if possible
+        if index < points.length - 1
+          next_point = points[index + 1]
+          time_diff = next_point.timestamp - point.timestamp
+
+          if time_diff > 0
+            distance = point.distance_to(next_point) * 1000
+            point.velocity&.to_f = distance / time_diff
+          else
+            point.velocity&.to_f = 0
+          end
+        else
+          # If this is the only point, default to 0
+          point.velocity&.to_f = 0
+        end
+      end
+    end
+
+    points
+  end
+
+  def modes_by_speed(speed_km_h)
+    MODES.select { |_, range| speed_km_h.between?(range[:min], range[:max]) }.keys
+  end
+
+  def restricted_modes_at_location(point)
+    restricted = []
+    favored_mode = nil
+
+    # Use Geocoder to get details about location type
+    results = Geocoder.search([point.lat, point.lon]).first
+    return [restricted, favored_mode] unless results && results.data
+
+    data = results.data
+
+    # Check for highways/roads and favor car on them
+    if data["highway"]
+      if ["motorway", "trunk", "primary", "secondary", "tertiary", "residential", "unclassified"].include?(data["highway"])
+        favored_mode = :car
+      end
+
+      # Restrict walking/running on major highways
+      if ["motorway", "trunk", "primary"].include?(data["highway"])
+        restricted += RESTRICTED_MODES["highway"]
+      end
+    end
+
+    # Favor walking on pedestrian ways
+    if data["highway"] && ["pedestrian", "footway", "steps", "path"].include?(data["highway"])
+      favored_mode = :walking
+    end
+
+    # Check for railways and favor train
+    if data["railway"] || (data["infrastructure"] && data["infrastructure"].include?("railway"))
+      restricted += RESTRICTED_MODES["railway"]
+      favored_mode = :train if data["railway"] == "rail"
+    end
+
+    # Check for water bodies and favor boat
+    if data["natural"] == "water" || data["water"] || data["waterway"]
+      restricted += RESTRICTED_MODES["water"]
+      favored_mode = :boat
+    end
+
+    # Check for airports/airfields and favor plane
+    if data["aeroway"]
+      restricted += RESTRICTED_MODES["aeroway"]
+      favored_mode = :plane if data["aeroway"] == "runway" || data["aeroway"] == "taxiway"
+    end
+
+    [restricted.uniq, favored_mode]
+  end
+
+  def best_consistent_mode(possible_modes, previous_mode, current_speed, previous_speed)
+    return possible_modes.first if possible_modes.size == 1
+
+    # If speed delta is small, prefer the previous mode's "family"
+    speed_delta = (current_speed - previous_speed).abs
+
+    if speed_delta < 10
+      # Group similar modes
+      land_vehicles = [:car, :motorbike]
+      human_powered = [:walking, :running, :bicycle]
+
+      if land_vehicles.include?(previous_mode) && (possible_modes & land_vehicles).any?
+        return (possible_modes & land_vehicles).first
+      elsif human_powered.include?(previous_mode) && (possible_modes & human_powered).any?
+        return (possible_modes & human_powered).first
+      end
+    end
+
+    # Otherwise pick the mode closest to current speed's midpoint in its range
+    most_likely_mode(possible_modes, current_speed)
+  end
+
+  def most_likely_mode(possible_modes, speed_km_h)
+    return possible_modes.first if possible_modes.size == 1
+
+    # Find the mode whose speed range midpoint is closest to the current speed
+    possible_modes.min_by do |mode|
+      range = MODES[mode]
+      midpoint = (range[:min] + range[:max]) / 2.0
+      (speed_km_h - midpoint).abs
+    end
+  end
+
+  def smooth_isolated_mode_changes(results)
+    # Minimum segment length (in points) to keep
+    min_segment_length = 3
+
+    # Identify segments
+    segments = []
+    current_segment = { mode: results.first[:mode], start_idx: 0, end_idx: 0 }
+
+    results.each_with_index do |result, idx|
+      if result[:mode] == current_segment[:mode]
+        current_segment[:end_idx] = idx
+      else
+        segments << current_segment
+        current_segment = { mode: result[:mode], start_idx: idx, end_idx: idx }
+      end
+    end
+    segments << current_segment
+
+    # Fix short segments sandwiched between the same mode
+    segments.each_with_index do |segment, idx|
+      next if idx == 0 || idx == segments.size - 1
+      prev_segment = segments[idx - 1]
+      next_segment = segments[idx + 1]
+
+      # If short segment is between two segments of the same mode, convert it
+      if segment[:end_idx] - segment[:start_idx] + 1 < min_segment_length &&
+         prev_segment[:mode] == next_segment[:mode]
+        (segment[:start_idx]..segment[:end_idx]).each do |i|
+          results[i][:mode] = prev_segment[:mode]
+        end
+      end
+    end
+
+    results
+  end
+end