gem "mppx"

require "mppx"

# Define a payment method with name, intent, and schema
method = Mppx::Method.from(
  name: "tempo",
  intent: "charge",
  schema: {
    request: ->(r) { r },
    credential: { payload: ->(p) { p } }
  }
)

# Configure the server method with a verification callback
server_method = Mppx::Method.to_server(method,
  verify: ->(credential:, request:) {
    # Verify the payment and return receipt data
    Mppx::Receipt.from(
      method: "tempo",
      reference: "tx_123",
      status: "success",
      timestamp: Time.now.utc.iso8601
    )
  }
)

# Create a handler
handler = Mppx::Server::Handler.create(
  methods: [server_method],
  secret_key: ENV["MPP_SECRET_KEY"],
  realm: "My API"
)

# In your Rack app or Rails config
use Mppx::Server::Middleware,
  handler: handler,
  method_key: "charge",
  options: { amount: "0.01", currency: "USD" }

# Parse the 402 challenge from response headers
challenge = Mppx::Challenge.from_headers(response_headers)

# Create a credential with payment proof
credential = Mppx::Credential.from(
  challenge: challenge,
  payload: { transaction_hash: "0xabc..." }
)

# Serialize for the Authorization header
auth_header = Mppx::Credential.serialize(credential)
# => "Payment eyJjaGFsbGVuZ2U..."

receipt = Mppx::Receipt.from_response(response_headers)
# => { method: "tempo", reference: "tx_123", status: "success", timestamp: "..." }