/**
 * AP-UX-1 — UX Composition Resolver (Frontend-Spiegel des Steering Kernels).
 */

import { hasSteeringElement, steeringElementUi } from '../registry/steeringElementRegistry.js'
import { getWidgetByKey } from '../registry/widgetRegistry.js'
import { filterSprintProposals } from '../utils/steeringProposals.js'
import { COMPOSITION_PROVIDERS, getProvidersForSlot } from './compositionProviders.js'
import { COMPOSITION_SURFACES, getCompositionSurface, surfaceKeyFor } from './uiSlotRegistry.js'

/** @typedef {import('./compositionProviders.js').CompositionProviderDefinition} CompositionProviderDefinition */

/**
 * @typedef {Object} CompositionInput
 * @property {string} [surfaceKey]
 * @property {string} [mode]
 * @property {string | null} [routeKey]
 * @property {'portfolio' | 'initiative'} [scope]
 * @property {string[] | null} [steeringElements]
 * @property {object | null} [operatingContext]
 * @property {object | null} [steeringSnapshot]
 * @property {Set<string> | string[]} [capabilities]
 * @property {Record<string, unknown>} [filterContext]
 * @property {object | null} [opsContext]
 */

/**
 * @typedef {CompositionProviderDefinition & { instanceKey: string, props: Record<string, unknown> }} ResolvedProvider
 */

const CONDITIONAL_PREDICATES = {
  hasRoadblockers(ctx) {
    const counts = ctx.steeringSnapshot?.counts || {}
    return (counts.actions_blocked || 0) > 0 || (counts.blockers_open || 0) > 0
  },
  hasActiveWorkCycle(ctx) {
    const cycle =
      ctx.steeringSnapshot?.active_work_cycle
      || ctx.opsContext?.activeWorkCycle
      || null
    return Boolean(cycle?.id)
  },
  isProductWithoutActiveSprint(ctx) {
    if (CONDITIONAL_PREDICATES.hasActiveWorkCycle(ctx)) return false
    const features =
      ctx.operatingContext?.ui_features
      || ctx.opsContext?.uiFeatures
      || {}
    const slices =
      ctx.operatingContext?.data_slices
      || ctx.opsContext?.dataSlices
      || []
    return Boolean(features.continuousProductWorkMode && slices.includes('work_cycles'))
  },
}

/**
 * @param {Set<string> | string[] | undefined} capabilities
 * @param {string | undefined} required
 */
function hasCapability(capabilities, required) {
  if (!required) return true
  const capSet = capabilities instanceof Set ? capabilities : new Set(capabilities || [])
  return capSet.has(required)
}

/**
 * @param {CompositionInput} input
 */
function resolveSteeringElements(input) {
  if (Array.isArray(input.steeringElements)) return input.steeringElements
  return input.operatingContext?.steering_elements || []
}

/**
 * @param {CompositionInput} input
 */
function resolveKernelProposals(input) {
  return input.steeringSnapshot?.steering_kernel?.proposals || {}
}

/**
 * @param {CompositionInput} input
 */
function resolveAgentSlots(input) {
  return (
    input.steeringSnapshot?.agent_slots
    || input.steeringSnapshot?.steering_kernel?.agent_slots
    || []
  )
}

/**
 * Next-Action-Überschriften: kritischster passender steering_element (Priorität).
 * @param {string[]} elements
 * @param {object | null | undefined} steeringSnapshot
 */
export function resolveNextActionUi(elements, steeringSnapshot) {
  const priority = [
    'critical_path',
    'recurring_rhythm',
    'work_cycle_scope',
    'maturity_stage',
    'gate_fulfillment',
    'queue_inbox',
  ]
  const hasActiveSprint = Boolean(steeringSnapshot?.active_work_cycle)
  for (const key of priority) {
    if (key === 'work_cycle_scope' && !hasActiveSprint) continue
    const ui = steeringElementUi(elements, key)
    if (ui?.nextActionTitle) return ui
  }
  return null
}

/**
 * @param {CompositionProviderDefinition} provider
 * @param {CompositionInput} input
 */
function isProviderActive(provider, input) {
  const scope = input.scope || 'portfolio'
  const scopeTypes = provider.scopeTypes || ['portfolio', 'initiative']
  if (!scopeTypes.includes(scope)) return false
  if (!hasCapability(input.capabilities, provider.requiresCapability)) return false

  const elements = resolveSteeringElements(input)
  const proposals = resolveKernelProposals(input)
  const agentSlots = resolveAgentSlots(input)

  switch (provider.kind) {
    case 'steering_element':
      return hasSteeringElement(elements, provider.steeringElement)
    case 'proposal': {
      const key = provider.proposalKey
      if (!key) return false
      let items = proposals[key] || []
      if (key === 'sprint_commit' && input.filterContext?.workCycleId) {
        items = filterSprintProposals(items, input.filterContext.workCycleId)
      }
      return items.length > 0
    }
    case 'agent_slots':
      return agentSlots.length > 0
    case 'widget': {
      const widget = getWidgetByKey(provider.widgetKey)
      if (!widget) return false
      return hasCapability(input.capabilities, widget.requiredCapability)
    }
    case 'conditional': {
      const fn = CONDITIONAL_PREDICATES[provider.predicateKey]
      return typeof fn === 'function' ? fn(input) : false
    }
    case 'core':
    default:
      return true
  }
}

/**
 * @param {CompositionProviderDefinition} provider
 * @param {CompositionInput} input
 */
export function buildProviderProps(provider, input) {
  const ops = input.opsContext || {}
  const proposals = resolveKernelProposals(input)
  const agentSlots = resolveAgentSlots(input)
  const elements = resolveSteeringElements(input)
  const capabilities = input.capabilities instanceof Set
    ? input.capabilities
    : new Set(input.capabilities || [])

  switch (provider.componentKey) {
    case 'SteeringSnapshotPanel':
      return {
        snapshot: input.steeringSnapshot,
        loading: ops.steeringSnapshotLoading,
        error: ops.steeringSnapshotError,
        methods: ops.steeringMethods,
        canManageMethod: capabilities.has('kairo.initiative.manage'),
        onMethodChange: ops.handleMethodChange,
        methodBusy: ops.methodBusy,
        showGateHorizon: hasSteeringElement(elements, 'gate_fulfillment'),
      }
    case 'CriticalPathPanel': {
      const kernel = input.steeringSnapshot?.steering_kernel
      return {
        initiativeId: ops.initiativeId,
        actions: ops.actions || [],
        graphState: kernel?.read_models?.execution_graph ?? null,
        graphLoading: ops.steeringSnapshotLoading,
        scopeRoadmapItemId: kernel?.horizon?.gate_roadmap_item_id ?? null,
      }
    }
    case 'MaturityStagePanel':
      return {
        initiativeId: ops.initiativeId,
        roadmapItems: ops.roadmapItems || [],
      }
    case 'RecurringRhythmPanel':
      return {
        initiativeId: ops.initiativeId,
        recurringItems: ops.recurringItems || [],
      }
    case 'WorkTodayPracticePanel':
      return {
        initiativeId: ops.initiativeId,
        recurringItems: ops.recurringItems || [],
        canManage: capabilities.has('kairo.recurring.manage'),
        busy: ops.formBusy,
        onCompleted: async () => {
          if (typeof ops.refreshOm === 'function') {
            await ops.refreshOm(['recurring', 'steering_snapshot'])
          }
        },
      }
    case 'NextActionWidget': {
      const nextActionUi = resolveNextActionUi(elements, input.steeringSnapshot)
      return {
        scope: 'initiative',
        initiativeId: ops.initiativeId,
        items: input.steeringSnapshot?.next_actions,
        loading: ops.steeringSnapshotLoading,
        embedded: true,
        title: nextActionUi?.nextActionTitle,
        subtitle: nextActionUi?.nextActionSubtitle,
      }
    }
    case 'AgentSlotsPanel':
      return {
        slots: agentSlots,
        loading: ops.steeringSnapshotLoading,
      }
    case 'RoadblockersStrip': {
      const counts = input.steeringSnapshot?.counts || {}
      return {
        initiativeId: ops.initiativeId,
        actionsBlocked: counts.actions_blocked || 0,
        blockersOpen: counts.blockers_open || 0,
      }
    }
    case 'SteeringProposalsPanel':
      return {
        proposalsByKey: proposals,
        proposalKeys: provider.proposalKey ? [provider.proposalKey] : undefined,
        filterContext: input.filterContext || {},
        backlogVocabulary: input.operatingContext?.backlog_vocabulary,
        canManage: capabilities.has('kairo.backlog.manage'),
        onAcceptBacklogProposal: ops.onAcceptBacklogProposal,
        busy: ops.formBusy,
      }
    case 'WidgetHost': {
      const widget = getWidgetByKey(provider.widgetKey)
      return { widget }
    }
    case 'WorkActionsPanel':
      return {
        variant: provider.workActionsVariant || 'today',
        defaultCollapsed: true,
      }
    default:
      return {}
  }
}

/**
 * @param {CompositionProviderDefinition} provider
 * @param {CompositionInput} input
 * @returns {ResolvedProvider | null}
 */
export function resolveProviderInstance(provider, input) {
  if (!isProviderActive(provider, input)) return null
  return {
    ...provider,
    instanceKey: `${provider.key}:${provider.slotKeys[0]}`,
    props: buildProviderProps(provider, input),
  }
}

/**
 * @param {string} slotKey
 * @param {CompositionInput} input
 * @returns {ResolvedProvider[]}
 */
export function resolveSlotComposition(slotKey, input) {
  return getProvidersForSlot(slotKey)
    .map((provider) => resolveProviderInstance(provider, input))
    .filter(Boolean)
}

/**
 * @param {CompositionInput} input
 */
export function resolveSteeringComposition(input) {
  const surfaceKey = input.surfaceKey
    || surfaceKeyFor(/** @type {import('./uiSlotRegistry.js').CompositionMode} */ (input.mode), input.routeKey ?? null)
  const surface = getCompositionSurface(surfaceKey)
  if (!surface) {
    return { surfaceKey, slots: {} }
  }

  /** @type {Record<string, ResolvedProvider[]>} */
  const slots = {}
  for (const slotKey of surface.slotKeys) {
    slots[slotKey] = resolveSlotComposition(slotKey, input)
  }
  return { surfaceKey, slots }
}

/** Exported for tests */
export { COMPOSITION_PROVIDERS, isProviderActive, CONDITIONAL_PREDICATES }