# frozen_string_literal: true

namespace :reporting_events_rollup do
  desc 'Backfill rollup table from historical reporting events'
  task backfill: :environment do
    ReportingEventsRollupBackfill.new.run
  end
end

class ReportingEventsRollupBackfill # rubocop:disable Metrics/ClassLength
  def run
    print_header
    account = prompt_account
    timezone = resolve_timezone(account)
    first_event, last_event = discover_events(account)
    start_date, end_date, total_days = resolve_date_range(account, timezone, first_event, last_event)
    dry_run = prompt_dry_run?
    print_plan(account, timezone, start_date, end_date, total_days, first_event, last_event, dry_run)
    return if dry_run

    confirm_and_execute(account, start_date, end_date, total_days)
  end

  private

  def print_header
    puts ''
    puts color('=' * 70, :cyan)
    puts color('Reporting Events Rollup Backfill', :bold, :cyan)
    puts color('=' * 70, :cyan)
    puts color('Plan:', :bold, :yellow)
    puts '1. Ensure account.reporting_timezone is set before running this task.'
    puts '2. Wait for the current day to end in that account timezone.'
    puts '3. Run backfill for closed days only (today is skipped by default).'
    puts '4. Verify parity, then enable reporting_events_rollup read path.'
    puts ''
    puts color('Note:', :bold, :yellow)
    puts '- This task always uses account.reporting_timezone.'
    puts '- Default range is first event day -> yesterday (in account timezone).'
    puts ''
  end

  def prompt_account
    print 'Enter Account ID: '
    account_id = $stdin.gets.chomp
    abort color('Error: Account ID is required', :red, :bold) if account_id.blank?

    account = Account.find_by(id: account_id)
    abort color("Error: Account with ID #{account_id} not found", :red, :bold) unless account

    puts color("Found account: #{account.name}", :gray)
    puts ''
    account
  end

  def resolve_timezone(account)
    timezone = account.reporting_timezone
    abort color("Error: Account #{account.id} must have reporting_timezone set", :red, :bold) if timezone.blank?
    abort color("Error: Account #{account.id} has invalid reporting_timezone '#{timezone}'", :red, :bold) if ActiveSupport::TimeZone[timezone].blank?

    puts color("Using account reporting timezone: #{timezone}", :gray)
    puts ''
    timezone
  end

  def discover_events(account)
    first_event = account.reporting_events.order(:created_at).first
    last_event = account.reporting_events.order(:created_at).last

    if first_event.nil?
      puts ''
      puts "No reporting events found for account #{account.id}"
      puts 'Nothing to backfill.'
      exit(0)
    end

    [first_event, last_event]
  end

  def resolve_date_range(account, timezone, first_event, last_event)
    dates = discovered_dates(timezone, first_event, last_event)
    print_discovered_date_range(account, dates)
    build_date_range(dates)
  end

  def prompt_dry_run?
    print 'Dry run? (y/N): '
    input = $stdin.gets.chomp.downcase
    puts ''
    %w[y yes].include?(input)
  end

  # rubocop:disable Metrics/ParameterLists
  def print_plan(account, timezone, start_date, end_date, total_days, first_event, last_event, dry_run)
    zone = ActiveSupport::TimeZone[timezone]
    print_plan_summary(account, timezone, start_date, end_date, total_days, zone, first_event, last_event, dry_run)

    return unless dry_run

    puts color("DRY RUN MODE: Would process #{total_days} days", :yellow, :bold)
    puts "Would use account reporting_timezone '#{timezone}'"
    puts 'Run without dry run to execute backfill'
  end
  # rubocop:enable Metrics/ParameterLists

  def print_plan_summary(account, timezone, start_date, end_date, total_days, zone, first_event, last_event, dry_run) # rubocop:disable Metrics/ParameterLists
    puts color('=' * 70, :cyan)
    puts color('Backfill Plan Summary', :bold, :cyan)
    puts color('=' * 70, :cyan)
    puts "Account:     #{account.name} (ID: #{account.id})"
    puts "Timezone:    #{timezone}"
    puts "Date Range:  #{start_date} to #{end_date} (#{total_days} days)"
    puts "First Event: #{format_event_time(first_event, zone)}"
    puts "Last Event:  #{format_event_time(last_event, zone)}"
    puts "Dry Run:     #{dry_run ? 'YES (no data will be written)' : 'NO'}"
    puts color('=' * 70, :cyan)
    puts ''
  end

  def format_event_time(event, zone)
    event.created_at.in_time_zone(zone).strftime('%Y-%m-%d %H:%M:%S %Z')
  end

  def discovered_dates(timezone, first_event, last_event)
    tz = ActiveSupport::TimeZone[timezone]
    discovered_start = first_event.created_at.in_time_zone(tz).to_date
    discovered_end = last_event.created_at.in_time_zone(tz).to_date

    {
      discovered_start: discovered_start,
      discovered_end: discovered_end,
      discovered_days: (discovered_end - discovered_start).to_i + 1,
      default_end: [discovered_end, Time.current.in_time_zone(tz).to_date - 1.day].min
    }
  end

  def print_discovered_date_range(account, dates)
    message = "Discovered date range: #{dates[:discovered_start]} to #{dates[:discovered_end]} " \
              "(#{dates[:discovered_days]} days) [Account: #{account.name}]"
    puts color(message, :gray)
    puts color("Default end date (excluding today): #{dates[:default_end]}", :gray)
    puts ''
  end

  def build_date_range(dates)
    start_date = dates[:discovered_start]
    end_date = dates[:default_end]
    total_days = (end_date - start_date).to_i + 1

    abort_no_closed_days if total_days <= 0

    [start_date, end_date, total_days]
  end

  def abort_no_closed_days
    puts 'No closed days available to backfill in the default range.'
    exit(0)
  end

  def confirm_and_execute(account, start_date, end_date, total_days)
    if total_days > 730
      puts color("WARNING: Large backfill detected (#{total_days} days / #{(total_days / 365.0).round(1)} years)", :yellow, :bold)
      puts ''
    end

    print 'Proceed with backfill? (y/N): '
    confirm = $stdin.gets.chomp.downcase
    abort 'Backfill cancelled' unless %w[y yes].include?(confirm)

    puts ''
    execute_backfill(account, start_date, end_date, total_days)
  end

  def execute_backfill(account, start_date, end_date, total_days)
    puts 'Processing dates...'
    puts ''

    start_time = Time.current
    days_processed = 0

    (start_date..end_date).each do |date|
      ReportingEvents::BackfillService.backfill_date(account, date)
      days_processed += 1
      percentage = (days_processed.to_f / total_days * 100).round(1)
      print "\r#{date} | #{days_processed}/#{total_days} days | #{percentage}%    "
      $stdout.flush
    end

    print_success(account, days_processed, total_days, Time.current - start_time)
  rescue StandardError => e
    print_failure(e, days_processed, total_days)
  else
    prompt_enable_rollup_read_path(account)
  end

  def print_success(account, days_processed, _total_days, elapsed_time)
    puts "\n\n"
    puts color('=' * 70, :green)
    puts color('BACKFILL COMPLETE', :bold, :green)
    puts color('=' * 70, :green)
    puts "Total Days Processed: #{days_processed}"
    puts "Total Time:           #{elapsed_time.round(2)} seconds"
    puts "Average per Day:      #{(elapsed_time / days_processed).round(3)} seconds"
    puts ''
    puts 'Next steps:'
    puts '1. Verify parity before enabling the reporting_events_rollup read path.'
    puts '2. Verify rollups in database:'
    puts "   ReportingEventsRollup.where(account_id: #{account.id}).count"
    puts '3. Test reports to compare rollup vs raw performance'
    puts color('=' * 70, :green)
  end

  def prompt_enable_rollup_read_path(account)
    if account.feature_enabled?(:report_rollup)
      puts color('report_rollup is already enabled for this account.', :yellow, :bold)
      return
    end

    print 'Enable report_rollup read path now? Only do this after parity verification. (y/N): '
    confirm = $stdin.gets.to_s.chomp.downcase
    puts ''
    return unless %w[y yes].include?(confirm)

    account.enable_features!('report_rollup')
    puts color("Enabled report_rollup for account #{account.id}", :green, :bold)
  end

  def print_failure(error, days_processed, total_days)
    puts "\n\n"
    puts color('=' * 70, :red)
    puts color('BACKFILL FAILED', :bold, :red)
    puts color('=' * 70, :red)
    print_error_details(error)
    print_progress(days_processed, total_days)
    exit(1)
  end

  def print_error_details(error)
    puts color("Error: #{error.class.name} - #{error.message}", :red, :bold)
    puts ''
    puts 'Stack trace:'
    puts error.backtrace.first(10).map { |line| "  #{line}" }.join("\n")
    puts ''
  end

  def print_progress(days_processed, total_days)
    percentage = (days_processed.to_f / total_days * 100).round(1)
    puts "Processed: #{days_processed}/#{total_days} days (#{percentage}%)"
    puts color('=' * 70, :red)
  end

  ANSI_COLORS = {
    reset: "\e[0m",
    bold: "\e[1m",
    red: "\e[31m",
    green: "\e[32m",
    yellow: "\e[33m",
    cyan: "\e[36m",
    gray: "\e[90m"
  }.freeze

  def color(text, *styles)
    return text unless $stdout.tty?

    codes = styles.filter_map { |style| ANSI_COLORS[style] }.join
    "#{codes}#{text}#{ANSI_COLORS[:reset]}"
  end
end