# Code

require 'stripe'

Stripe::api_key = ENV['STRIPE_SECRET_KEY']

product1 = Stripe::Product.create(name: "Gold plan #{rand(9999999999)}")
plan1 = Stripe::Plan.create(interval: 'month', currency: 'jpy', amount: 5000, product: product1.id, usage_type: 'licensed')

product2 = Stripe::Product.create(name: "Silver plan #{rand(9999999999)}")
plan2 = Stripe::Plan.create(interval: 'month', currency: 'jpy', amount: 3000, product: product2.id, usage_type: 'licensed')

product3 = Stripe::Product.create(name: "Bronse plan #{rand(9999999999)}")
plan3 = Stripe::Plan.create(interval: 'month', currency: 'jpy', amount: 1000, product: product3.id, usage_type: 'licensed')

tax_rate = Stripe::TaxRate.create(display_name: 'Tax Rate', percentage: 10.0, inclusive: false)
customer = Stripe::Customer.create
payment_method = Stripe::PaymentMethod.create(type: 'card', card: { number: '4242424242424242', exp_year: 2030, exp_month: 01})
customer_payment_method = Stripe::PaymentMethod.attach(payment_method.id, customer: customer.id)

# https://stripe.com/docs/api/subscription_schedules/create
subscription_schedule = Stripe::SubscriptionSchedule.create(
  {
    customer: customer.id,
    start_date: Time.now.to_i + 60*60,
    phases: [
      {
        plans:
          [
            { plan: plan1.id, quantity: 1 },
          ],
          default_payment_method: customer_payment_method.id,
          default_tax_rates: [tax_rate],
          iterations: 1,
      },
      {
        plans:
          [
            { plan: plan2.id, quantity: 1 },
          ],
          default_payment_method: customer_payment_method.id,
          default_tax_rates: [tax_rate],
          iterations: 2,
      }
    ],
  }
)

puts '-' * 100
puts "Subscription Schedule created"
puts "https://dashboard.stripe.com/test/subscription_schedules/#{subscription_schedule.id}"
puts '-' * 100
puts subscription_schedule

# https://stripe.com/docs/api/subscription_schedules/update
# no customer id because already knows customer
# no start_date because already set start_date when created
#
# If no phases has start_date
# Stripe::InvalidRequestError: The subscription schedule update is missing at least one phase with a `start_date` to anchor end dates to.

# REMOVE plan1
# ADD again plan 2
# ADD new plan3
updated_subscription_schedule = Stripe::SubscriptionSchedule.update(
  subscription_schedule.id,
  {
    phases: [
      {
        plans:
          [
            { plan: plan2.id, quantity: 1 },
          ],
          default_payment_method: customer_payment_method.id,
          default_tax_rates: [tax_rate],
          iterations: 3,
          start_date: Time.now.to_i + 60*60,
      },
      {
        plans:
          [
            { plan: plan3.id, quantity: 1 },
          ],
          default_payment_method: customer_payment_method.id,
          default_tax_rates: [tax_rate],
          iterations: 4,
      }
    ]
  }
)

puts '-' * 100
puts "Subscription Schedule updated"
puts "https://dashboard.stripe.com/test/subscription_schedules/#{updated_subscription_schedule.id}"
puts '-' * 100
puts updated_subscription_schedule

----------------------------------------------------------------------------------------------------
Subscription Schedule created
https://dashboard.stripe.com/test/subscription_schedules/sub_sched_1Fuc1DCmti5jpytUKi62lAzm
----------------------------------------------------------------------------------------------------
{
  "id": "sub_sched_1Fuc1DCmti5jpytUKi62lAzm",
  "object": "subscription_schedule",
  "canceled_at": null,
  "completed_at": null,
  "created": 1577526935,
  "current_phase": null,
  "customer": "cus_GRV15kbeph5URv",
  "default_settings": {
    "billing_thresholds": null,
    "collection_method": "charge_automatically",
    "default_payment_method": null,
    "default_source": null,
    "invoice_settings": null
  },
  "end_behavior": "release",
  "livemode": false,
  "metadata": {
  },
  "phases": [
    {
      "application_fee_percent": null,
      "billing_thresholds": null,
      "collection_method": null,
      "coupon": null,
      "default_payment_method": "pm_1Fuc1CCmti5jpytUVOXozqqT",
      "default_tax_rates": [
        {
          "id": "txr_1Fuc1BCmti5jpytUJhjPKOkr",
          "object": "tax_rate",
          "active": true,
          "created": 1577526933,
          "description": null,
          "display_name": "Tax Rate",
          "inclusive": false,
          "jurisdiction": null,
          "livemode": false,
          "metadata": {
          },
          "percentage": 10.0
        }
      ],
      "end_date": 1580208934,
      "invoice_settings": null,
      "plans": [
        {
          "billing_thresholds": null,
          "plan": "plan_GRV1VgD9k7xx7K",
          "quantity": 1,
          "tax_rates": [

          ]
        }
      ],
      "prorate": true,
      "start_date": 1577530534,
      "tax_percent": 10.0,
      "trial_end": null
    },
    {
      "application_fee_percent": null,
      "billing_thresholds": null,
      "collection_method": null,
      "coupon": null,
      "default_payment_method": "pm_1Fuc1CCmti5jpytUVOXozqqT",
      "default_tax_rates": [
        {
          "id": "txr_1Fuc1BCmti5jpytUJhjPKOkr",
          "object": "tax_rate",
          "active": true,
          "created": 1577526933,
          "description": null,
          "display_name": "Tax Rate",
          "inclusive": false,
          "jurisdiction": null,
          "livemode": false,
          "metadata": {
          },
          "percentage": 10.0
        }
      ],
      "end_date": 1585392934,
      "invoice_settings": null,
      "plans": [
        {
          "billing_thresholds": null,
          "plan": "plan_GRV1MyHhrpvp0e",
          "quantity": 1,
          "tax_rates": [

          ]
        }
      ],
      "prorate": true,
      "start_date": 1580208934,
      "tax_percent": 10.0,
      "trial_end": null
    }
  ],
  "released_at": null,
  "released_subscription": null,
  "renewal_interval": null,
  "revision": "sub_sched_rev_1Fuc1DCmti5jpytU3JXMhiLq",
  "status": "not_started",
  "subscription": null
}
----------------------------------------------------------------------------------------------------
Subscription Schedule updated
https://dashboard.stripe.com/test/subscription_schedules/sub_sched_1Fuc1DCmti5jpytUKi62lAzm
----------------------------------------------------------------------------------------------------
{
  "id": "sub_sched_1Fuc1DCmti5jpytUKi62lAzm",
  "object": "subscription_schedule",
  "canceled_at": null,
  "completed_at": null,
  "created": 1577526935,
  "current_phase": null,
  "customer": "cus_GRV15kbeph5URv",
  "default_settings": {
    "billing_thresholds": null,
    "collection_method": "charge_automatically",
    "default_payment_method": null,
    "default_source": null,
    "invoice_settings": {
      "days_until_due": null
    }
  },
  "end_behavior": "release",
  "livemode": false,
  "metadata": {
  },
  "phases": [
    {
      "application_fee_percent": null,
      "billing_thresholds": null,
      "collection_method": null,
      "coupon": null,
      "default_payment_method": "pm_1Fuc1CCmti5jpytUVOXozqqT",
      "default_tax_rates": [
        {
          "id": "txr_1Fuc1BCmti5jpytUJhjPKOkr",
          "object": "tax_rate",
          "active": true,
          "created": 1577526933,
          "description": null,
          "display_name": "Tax Rate",
          "inclusive": false,
          "jurisdiction": null,
          "livemode": false,
          "metadata": {
          },
          "percentage": 10.0
        }
      ],
      "end_date": 1585392935,
      "invoice_settings": null,
      "plans": [
        {
          "billing_thresholds": null,
          "plan": "plan_GRV1MyHhrpvp0e",
          "quantity": 1,
          "tax_rates": [

          ]
        }
      ],
      "prorate": true,
      "start_date": 1577530535,
      "tax_percent": 10.0,
      "trial_end": null
    },
    {
      "application_fee_percent": null,
      "billing_thresholds": null,
      "collection_method": null,
      "coupon": null,
      "default_payment_method": "pm_1Fuc1CCmti5jpytUVOXozqqT",
      "default_tax_rates": [
        {
          "id": "txr_1Fuc1BCmti5jpytUJhjPKOkr",
          "object": "tax_rate",
          "active": true,
          "created": 1577526933,
          "description": null,
          "display_name": "Tax Rate",
          "inclusive": false,
          "jurisdiction": null,
          "livemode": false,
          "metadata": {
          },
          "percentage": 10.0
        }
      ],
      "end_date": 1595933735,
      "invoice_settings": null,
      "plans": [
        {
          "billing_thresholds": null,
          "plan": "plan_GRV1rFG3m02W73",
          "quantity": 1,
          "tax_rates": [

          ]
        }
      ],
      "prorate": true,
      "start_date": 1585392935,
      "tax_percent": 10.0,
      "trial_end": null
    }
  ],
  "released_at": null,
  "released_subscription": null,
  "renewal_interval": null,
  "revision": "sub_sched_rev_1Fuc1DCmti5jpytU1FOdmZZ8",
  "status": "not_started",
  "subscription": null
}

Original by Github issue