package statemachine

import (
	"fmt"

	"provisioning/internal/model"
)

type Trigger string

const (
	TriggerRebuildRequested  Trigger = "RebuildRequested"
	TriggerPXEScriptServed   Trigger = "PXEScriptServed"
	TriggerAnswerServed      Trigger = "AnswerServed"
	TriggerInstallWebhook    Trigger = "InstallWebhook"
	TriggerPhoneHome         Trigger = "PhoneHome"
	TriggerClusterJoinStart  Trigger = "ClusterJoinStarted"
	TriggerJoinComplete      Trigger = "JoinComplete"
	TriggerFailed            Trigger = "Failed"
)

type transition struct {
	from []model.HostState
	to   model.HostState
}

var allActiveStates = []model.HostState{
	model.StatePXEReady,
	model.StatePXEBooted,
	model.StateInstalling,
	model.StateInstalled,
	model.StateFirstBoot,
	model.StateJoining,
}

var table = map[Trigger]transition{
	TriggerRebuildRequested: {
		from: []model.HostState{model.StateRegistered, model.StateReady, model.StateFailed},
		to:   model.StatePXEReady,
	},
	TriggerPXEScriptServed: {
		from: []model.HostState{model.StatePXEReady},
		to:   model.StatePXEBooted,
	},
	TriggerAnswerServed: {
		from: []model.HostState{model.StatePXEBooted},
		to:   model.StateInstalling,
	},
	TriggerInstallWebhook: {
		from: []model.HostState{model.StateInstalling},
		to:   model.StateInstalled,
	},
	TriggerPhoneHome: {
		from: []model.HostState{model.StateInstalled},
		to:   model.StateFirstBoot,
	},
	TriggerClusterJoinStart: {
		from: []model.HostState{model.StateFirstBoot},
		to:   model.StateJoining,
	},
	TriggerJoinComplete: {
		from: []model.HostState{model.StateJoining},
		to:   model.StateReady,
	},
	TriggerFailed: {
		from: allActiveStates,
		to:   model.StateFailed,
	},
}

func Next(current model.HostState, t Trigger) (model.HostState, error) {
	tr, ok := table[t]
	if !ok {
		return "", fmt.Errorf("unknown trigger %q", t)
	}
	for _, s := range tr.from {
		if s == current {
			return tr.to, nil
		}
	}
	return "", fmt.Errorf("trigger %q not allowed from state %q", t, current)
}