Full backup of MyFitnessPal food diaries as JSON

MyFitnessPal-backup.rb

#!/usr/bin/env ruby

require 'date'
require 'optparse'
require 'json'
require 'bundler/inline'

gemfile {
    source 'https://rubygems.org'
    gem 'mechanize'
    gem 'netrc'
}

def date_to_string( date )
    date.to_s.split("T").first
end

def login()
    netrc = Netrc.read

    mechanize_agent = Mechanize.new

    login_page = mechanize_agent.get( 'https://www.myfitnesspal.com/fr/account/login' )
    form = login_page.forms[0]
    form.username = netrc['myfitnesspal'].login
    form.password = netrc['myfitnesspal'].password
    form.submit

    mechanize_agent
end

def backup_day( agent, nickname, date )
    day_diary = agent.get( "https://www.myfitnesspal.com/food/diary/#{nickname}?date=#{date_to_string( date )}" )

    def extract_nutrients( tr )
        data = tr.elements.map(&:text)
        data = data[1 .. data.length - 2].map(&:strip)
                                         .map { |td| td.strip.split("\n").first.sub(",", "").to_i }

        { calories: data[0],
          carbs: data[1],
          fat: data[2],
          protein: data[3],
          sodium: data[4],
          sugar: data[5] }
    end

    def extract_meals( data )
        meals = []
        current_meal = {}

        data.at( "#diary-table tbody" ).elements
                                       .each do |element|
            if element.attributes.size > 0 && element.attributes["class"].value == "meal_header"
                current_meal = { name: element.at( "td.first" ).text,
                                 items: [] }
            elsif element.attributes.size > 0 && element.attributes["class"].value == "bottom"
                meals << current_meal
            elsif element.attributes.size > 0 && ["spacer", "total", "total alt", "total remaining"].include?( element.attributes["class"].value )
                next
            else
                item = { name: element.at("td.first").text.strip }

                current_meal[:items] << item.merge( extract_nutrients( element ) )
            end
        end

        meals
    end

    { date: date_to_string( date ),
      meals: extract_meals( day_diary ),
      consumed: extract_nutrients( day_diary.at( "tr.total" ) ),
      goals: extract_nutrients( day_diary.at( "tr.total.alt" ) )
    }
end

def backup_all( agent, nickname, from, to )
    backup = (from .. to).flat_map do |date|
        putc "."
        backup_day( agent, nickname, date )
    end
    putc "\n"

    backup
end

options = {}
OptionParser.new do |opts|
    opts.banner = "Usage: myfitnesspal-backup.rb [options]"

    opts.on("-n", "--nickname NICKNAME", "Nickname in MyFitnessPal") do |nickname|
        options[:nickname] = nickname
    end

    opts.on("-f", "--from DATE", "Starting date") do |from|
        options[:from] = DateTime.parse( from )
    end

    opts.on("-t", "--to DATE", "End date") do |to|
        options[:to] = DateTime.parse( to )
    end

    opts.on("-u", "--update", "Update existing file") do
        options[:update] = true
    end

    opts.on("-o", "--output FILENAME", "Filename") do |filename|
        options[:output] = filename
    end
end.parse!

raise OptionParser::MissingArgument unless options.key?( :nickname ) && ( options.key?( :from ) || options.key?( :update ) )

if options[:update]
    json = JSON.parse( File.read( options[:output] ) )
    options[:from] = DateTime.parse( json.map { |day| day["date"] }.sort.last ).next_day
end

options[:to] ||= DateTime.now

exit if options[:from] > options[:to]

agent = login()

data = backup_all( agent, options[:nickname], options[:from], options[:to] )

if options[:output]
    File.open( options[:output], "w" ) do |file|
        file.puts( JSON.pretty_generate( options[:update] ? json.concat( data ) : data ) )
    end
else
    puts JSON.pretty_generate( data )
end