import type { PlatformContext } from '../types'

export type ExperimentAwarePlatformContext = PlatformContext & {
  currentExperiment?: unknown
  currentExperimentId?: unknown
  experiment?: unknown
  experimentId?: unknown
}

export function getInjectedPlatformContext(): PlatformContext | undefined {
  if (typeof window === 'undefined') return undefined
  return (window as unknown as { __MINT_PLATFORM__?: PlatformContext }).__MINT_PLATFORM__
}

/** Return the platform's canonical plugin identity for the mounted frontend. */
export function resolveCurrentPluginId(): string | undefined {
  const pluginId = getInjectedPlatformContext()?.plugin?.id
  return typeof pluginId === 'string' && pluginId ? pluginId : undefined
}

export function getInjectedExperimentContext(): ExperimentAwarePlatformContext | undefined {
  return getInjectedPlatformContext() as ExperimentAwarePlatformContext | undefined
}

export function currentExperimentFromContext<TExperiment>(
  context: ExperimentAwarePlatformContext | undefined = getInjectedExperimentContext(),
): TExperiment | undefined {
  const candidate = context?.currentExperiment ?? context?.experiment
  return candidate && typeof candidate === 'object'
    ? candidate as TExperiment
    : undefined
}

export function currentExperimentIdFromContext(
  context: ExperimentAwarePlatformContext | undefined = getInjectedExperimentContext(),
): number | undefined {
  return parseExperimentId(
    context?.currentExperimentId ??
    context?.experimentId ??
    context?.currentExperiment ??
    context?.experiment,
  )
}

export function currentExperimentIdFromUrl(): number | undefined {
  if (typeof window === 'undefined') return undefined
  const location = window.location
  const params = new URLSearchParams(location?.search ?? '')
  return parseExperimentId(params.get('experimentId') ?? params.get('experiment_id'))
    ?? experimentIdFromPath(location?.pathname ?? '')
    ?? experimentIdFromPath((location?.hash ?? '').replace(/^#\/?/, '/'))
}

export function resolveCurrentExperimentId(
  context: ExperimentAwarePlatformContext | undefined = getInjectedExperimentContext(),
): number | undefined {
  return currentExperimentIdFromContext(context) ?? currentExperimentIdFromUrl()
}

export function parseExperimentId(value: unknown): number | undefined {
  if (typeof value === 'number' && Number.isFinite(value)) return value
  if (typeof value === 'string' && value.trim()) {
    const parsed = Number(value)
    return Number.isFinite(parsed) ? parsed : undefined
  }
  if (value && typeof value === 'object' && 'id' in value) {
    return parseExperimentId((value as { id?: unknown }).id)
  }
  return undefined
}

function experimentIdFromPath(path: string): number | undefined {
  const segments = path.split('/').filter(Boolean)
  for (let index = 0; index < segments.length - 1; index += 1) {
    const segment = segments[index]?.toLowerCase()
    if (segment === 'experiment' || segment === 'experiments') {
      return parseExperimentId(decodeURIComponent(segments[index + 1] ?? ''))
    }
  }
  return undefined
}