/**
 * Zentrale Routen & Rückkehr-Kontext Trainingsplanung ↔ Einheiten-Editor.
 * Alle Navigations-URLs für Kalender-Einheiten hier pflegen (Drift-Schutz).
 */

export const PLANNING_HUB_PATH = '/planning'

export function buildPlanUnitEditPath(unitId) {
  const id = Number(unitId)
  if (!Number.isFinite(id) || id < 1) return PLANNING_HUB_PATH
  return `/planning/units/${id}/edit`
}

/**
 * @param {{ groupId?: string|number, plannedDate?: string, templateId?: string|number, mode?: string }} opts
 */
export function buildPlanUnitNewPath(opts = {}) {
  const params = new URLSearchParams()
  if (opts.groupId != null && opts.groupId !== '') params.set('group', String(opts.groupId))
  if (opts.plannedDate) params.set('date', String(opts.plannedDate).slice(0, 10))
  if (opts.templateId != null && opts.templateId !== '') params.set('template', String(opts.templateId))
  if (opts.mode === 'debrief') params.set('mode', 'debrief')
  const q = params.toString()
  return q ? `/planning/units/new?${q}` : '/planning/units/new'
}

/** @param {import('react-router-dom').URLSearchParams|string|null|undefined} raw */
export function legacyPlanningUnitDeepLinkTarget(raw) {
  const params =
    raw instanceof URLSearchParams ? raw : new URLSearchParams(typeof raw === 'string' ? raw : '')
  const uid = params.get('unit')
  if (!uid) return null
  const idNum = parseInt(uid, 10)
  if (!Number.isFinite(idNum) || idNum < 1) return null
  const debrief = params.get('debrief')
  const base = buildPlanUnitEditPath(idNum)
  if (debrief === '1' || debrief === 'true') {
    return `${base}?mode=debrief`
  }
  return base
}

/**
 * @param {{
 *   selectedGroupId?: string,
 *   planView?: string,
 *   calendarMonthStr?: string,
 *   startDate?: string,
 *   endDate?: string,
 *   planScope?: string,
 *   assignedToMeOnly?: boolean,
 * }} hubState
 */
export function buildPlanningHubReturnState(hubState = {}) {
  return {
    v: 1,
    selectedGroupId: hubState.selectedGroupId != null ? String(hubState.selectedGroupId) : '',
    planView: hubState.planView || 'list',
    calendarMonthStr: hubState.calendarMonthStr || '',
    startDate: hubState.startDate || '',
    endDate: hubState.endDate || '',
    planScope: hubState.planScope || 'group',
    assignedToMeOnly: Boolean(hubState.assignedToMeOnly),
  }
}

/** @param {string} pathname */
export function isPlanningUnitEditorPath(pathname) {
  if (!pathname) return false
  if (pathname === '/planning/units/new') return true
  return /^\/planning\/units\/\d+\/edit$/.test(pathname)
}

/** @param {ReturnType<typeof buildPlanningHubReturnState>|null|undefined} state */
export function planningHubPathFromReturnState(state) {
  if (!state || state.v !== 1) return PLANNING_HUB_PATH
  const params = new URLSearchParams()
  if (state.selectedGroupId) params.set('group', state.selectedGroupId)
  if (state.planView && state.planView !== 'list') params.set('view', state.planView)
  if (state.planView === 'calendar' && state.calendarMonthStr) {
    params.set('month', state.calendarMonthStr)
  }
  if (state.startDate) params.set('start', state.startDate)
  if (state.endDate) params.set('end', state.endDate)
  if (state.planScope && state.planScope !== 'group') params.set('scope', state.planScope)
  if (state.assignedToMeOnly) params.set('mine', '1')
  const q = params.toString()
  return q ? `${PLANNING_HUB_PATH}?${q}` : PLANNING_HUB_PATH
}

/** Hub-Query beim Mount auf State-Felder mappen. */
export function parsePlanningHubQuery(searchParams) {
  const p = searchParams instanceof URLSearchParams ? searchParams : new URLSearchParams(searchParams || '')
  return {
    selectedGroupId: p.get('group') || '',
    planView: p.get('view') === 'calendar' ? 'calendar' : 'list',
    calendarMonthStr: p.get('month') || '',
    startDate: p.get('start') || '',
    endDate: p.get('end') || '',
    planScope: p.get('scope') === 'club' ? 'club' : 'group',
    assignedToMeOnly: p.get('mine') === '1',
  }
}