// Incident status workflow, shared so the web app can show the same options and reasons the API enforces.
import type { ActionStatus } from './api-types.ts'
import { hasRole, type IncidentStatus, type Role, type Severity } from './enums.ts'

export interface Transition {
  from: IncidentStatus
  to: IncidentStatus
  minRole: Role
  label: string
}

export const transitions: Transition[] = [
  { from: 'reported', to: 'triage', minRole: 'supervisor', label: 'Start triage' },
  { from: 'triage', to: 'investigation', minRole: 'supervisor', label: 'Start investigation' },
  { from: 'triage', to: 'actions', minRole: 'supervisor', label: 'Skip to corrective actions' },
  { from: 'triage', to: 'closed', minRole: 'supervisor', label: 'Close: no further action' },
  { from: 'investigation', to: 'actions', minRole: 'supervisor', label: 'Move to corrective actions' },
  { from: 'actions', to: 'investigation', minRole: 'supervisor', label: 'Back to investigation' },
  { from: 'actions', to: 'verification', minRole: 'supervisor', label: 'Send for verification' },
  { from: 'verification', to: 'actions', minRole: 'safety_manager', label: 'Return to actions' },
  { from: 'verification', to: 'closed', minRole: 'safety_manager', label: 'Verify and close' },
  { from: 'closed', to: 'investigation', minRole: 'safety_manager', label: 'Reopen' },
]

export interface WorkflowFacts {
  severity: Severity
  rootCauseCount: number
  actionStatuses: ActionStatus[]
}

/** Why a transition isn't possible yet, or undefined if it is. */
export function transitionBlocker(transition: Transition, facts: WorkflowFacts): string | undefined {
  const live = facts.actionStatuses.filter((status) => status !== 'cancelled')
  if (transition.from === 'triage' && transition.to === 'closed' && (facts.severity === 'high' || facts.severity === 'critical')) {
    return 'High and critical incidents must be investigated before closing'
  }
  if (transition.to === 'actions' && transition.from === 'investigation' && facts.rootCauseCount === 0) {
    return 'Record at least one root cause first'
  }
  if (transition.to === 'verification') {
    if (live.length === 0) return 'Add at least one corrective action first'
    if (live.some((status) => status === 'open' || status === 'in_progress')) return 'All corrective actions must be done first'
  }
  if (transition.from === 'verification' && transition.to === 'closed' && live.some((status) => status !== 'verified')) {
    return 'Verify every corrective action first'
  }
  return undefined
}

/** Transitions from `status` that `role` may perform, with blockers explained. */
export function availableTransitions(status: IncidentStatus, role: Role, facts: WorkflowFacts) {
  return transitions
    .filter((t) => t.from === status && hasRole(role, t.minRole))
    .map((t) => ({ to: t.to, label: t.label, blockedReason: transitionBlocker(t, facts) }))
}