Abstract Vehicle State Machine

GO implementaion of State transition for a abstract vehicle.
State transitions are performed based on the permission of user roles.

Technical requirements

• If the state transition is not valid, avsm return a descriptive error.
• If the state transition is valid, avsm return a nil error
• The library needs to have a reasonable performance to be used in a soft real­time API solution.
• The solution should include the git history.
• The solution must be stateless. Assume that any required state will be provided to the library.

User roles

• End­users ­ Regular app­users / riders.
• Hunters ­ End users who have signed up to be chargers of vehicles and are responsible for
• picking up low battery vehicles.
• 3. Admins ­ Super users who can do everything

Valid states

Operational statutes

• 1. Ready ­ The vehicle is operational and can be claimed by an end­user
• 2. Battery_low ­ The vehicle is low on battery but otherwise operational. The vehicle cannot be
• claimed by an end­user but can be claimed by a hunter.
• 3. Bounty ­ Only available for “Hunters” to be picked up for charging.
• 4. Riding ­ An end user is currently using this vehicle; it can not be claimed by another user or hunter.
• 5. Collected ­ A hunter has picked up a vehicle for charging.
• 6. Dropped ­ A hunter has returned a vehicle after being charged.

Not commissioned for service , not claimable by either end­users nor hunters.

• 7. Service_mode
• 8. Terminated
• 9. Unknown

Note

 This is a drafted and working version.
 This can be improved by implementing commandline functionalities.
 avsm pacakge can be divided into multiple modules.
 Hardcoded transition map can be modified via logic.

Installation

go get github.com/bhakiyakalimuthu/avsm

Usage

package main 

import (
	"github.com/bhakiyakalimuthu/avsm"
	"fmt"
	)

type T struct {
	V *avsm.Vehicle
}

func main() {
	fmt.Println("testing")
	t := &T{V: &avsm.Vehicle{}}

	// add initial rule 
	t.V.SetStateTransitionRules() // Ready state initiated by default
	// if err != nil {
	// 	// handle
	// }

	// Happy Journey 
	// All Happy state transition returns nill
	t.V.StateTransition("Riding","Hunter") // State is transited from Ready to Riding

	t.V.StateTransition("Ready","EndUser") // State is transited from Riding to Ready

	t.V.StateTransition("Bounty","Automatic") // State is transited from Ready to Bounty

	t.V.StateTransition("Collected","Hunter") // State is transited from Bounty to Collected

	t.V.StateTransition("Dropped","Hunter") // State is transited from Collected to Dropped

	t.V.StateTransition("Ready","Hunter") // State is transited from Dropped to Ready


	// Panic scenario 
	t.V.StateTransition("Riding","EndUser")
	errTransitionNotPermitted := t.V.StateTransition("Collected","Hunter") // transition from state Ready to collected  is not permitted.ErrorTransitionNotPermitted  
	fmt.Println(errTransitionNotPermitted)
	
	errRolePermissionDenied := t.V.StateTransition("BatteryLow","EndUser") // Invalid permission transition from state Riding to BatteryLow for a role EndUser.ErrorRolePermissionDenied
	fmt.Println(errRolePermissionDenied)

	// get the current state
	state := t.V.CurrentState() // "BatteryLow"
	fmt.Println(state)
}