@startuml

actor "Buyer \n[frontend]" as User
participant "Buyer \n[daemon]" as UserApp
participant "Seller \n[daemon]" as SellerApp
actor "Seller \n[frontend]" as Seller
participant Oracle as Oracle
participant Bitcoin as Bitcoin

Seller -> SellerApp: publish sell order
SellerApp -> Oracle: Attestation for sell order
Oracle --> SellerApp: Attestation pubkey
User -> UserApp: Start daemon & UI
UserApp -> SellerApp: fetch current sell order
SellerApp -->UserApp: current sell order
UserApp -> User: Show sell order (1)
User -> UserApp: Take order
UserApp -> SellerApp: Take request (incl. protocol params?)
SellerApp -> Seller: Notfiy seller about take request
Seller -> SellerApp: Accept
SellerApp --> UserApp: Take response (incl. protocol params?)
group DLC setup
UserApp -> SellerApp: protocol setup step 1..n
SellerApp --> UserApp: protocol setup step 1..n
note over UserApp : CETs generated
note over SellerApp : CETs generated
SellerApp -> Bitcoin: Publish DLC
SellerApp -> SellerApp: Update CFD state: open
SellerApp -> Seller: Sell position open
note over SellerApp : Assumption: \nSeller publishes DLC \nBuyer CET upon closing position
UserApp -> Bitcoin: Witness DLC
UserApp -> UserApp: Update CFD state: open
UserApp -> User: Buy position open
end group
Seller -> SellerApp: Republish new sell-order
group DLC settlement
User -> UserApp: Close long position
UserApp -> Oracle: request attestation
Oracle --> UserApp: attested price
UserApp -> Bitcoin: CET according to price
SellerApp -> SellerApp: Update position state to closed
SellerApp -> Seller: Position was closed
end group

@enduml