import type { CloudProvider, Region } from 'shared-data'
import { AWS_REGIONS } from 'shared-data'
import { SMART_REGION_TO_EXACT_REGION_MAP } from 'shared-data/regions'

import type { OrganizationAvailableRegionsData } from '@/data/organizations/organization-available-regions-query'
import { DesiredInstanceSize, instanceSizeSpecs } from '@/data/projects/new-project.constants'

export function smartRegionToExactRegion(smartOrExactRegion: string) {
  return SMART_REGION_TO_EXACT_REGION_MAP.get(smartOrExactRegion) ?? smartOrExactRegion
}

export function getAvailableRegions(
  cloudProvider: CloudProvider,
  environment = process.env.NEXT_PUBLIC_ENVIRONMENT
): Region {
  switch (cloudProvider) {
    case 'AWS':
    case 'AWS_K8S':
      return AWS_REGIONS
    case 'AWS_NIMBUS':
      if (environment !== 'prod') {
        // Only allow Southeast Asia for Nimbus (local/staging)
        return {
          SOUTHEAST_ASIA: AWS_REGIONS.SOUTHEAST_ASIA,
        }
      }

      // Only allow US East for Nimbus (prod)
      return {
        EAST_US: AWS_REGIONS.EAST_US,
      }
    default:
      throw new Error('Invalid cloud provider')
  }
}

type ResolveDefaultDbRegionArgs = {
  cloudProvider: CloudProvider
  isHighAvailabilityRestricted: boolean
  highAvailabilityRegionName: string | undefined
  isSmartRegionEnabled: boolean
  recommendedSmartRegion: string | undefined
  autoDefaultRegion: string | undefined
  fixedDefaultRegion: string
  environment?: string
}

export function resolveDefaultDbRegion({
  cloudProvider,
  isHighAvailabilityRestricted,
  highAvailabilityRegionName,
  isSmartRegionEnabled,
  recommendedSmartRegion,
  autoDefaultRegion,
  fixedDefaultRegion,
  environment = process.env.NEXT_PUBLIC_ENVIRONMENT,
}: ResolveDefaultDbRegionArgs): string | undefined {
  if (isHighAvailabilityRestricted) return highAvailabilityRegionName
  if (isSmartRegionEnabled) return recommendedSmartRegion

  // The geolocated default is only usable if the provider actually offers that region
  // (e.g. AWS_NIMBUS is restricted to a single region)
  const isAutoDefaultRegionAvailable = Object.entries(
    getAvailableRegions(cloudProvider, environment)
  ).some(([, region]) => region.displayName === autoDefaultRegion)

  return isAutoDefaultRegionAvailable && autoDefaultRegion !== undefined
    ? autoDefaultRegion
    : fixedDefaultRegion
}

/**
 * When launching new projects, they only get assigned a compute size once successfully launched,
 * this might assume wrong compute size, but only for projects being rapidly launched after one another on non-default compute sizes.
 *
 * Needs to be in the API in the future [kevin]
 */
export const monthlyInstancePrice = (instance: string | undefined): number => {
  return instanceSizeSpecs[instance as DesiredInstanceSize]?.priceMonthly || 10
}

export const instanceLabel = (instance: string | undefined): string => {
  return instanceSizeSpecs[instance as DesiredInstanceSize]?.label || 'Micro'
}

export const getHighAvailabilityRegionCode = (
  environment = process.env.NEXT_PUBLIC_ENVIRONMENT
) => {
  // Local dev stacks can run in any of the supported regions, so they're left unrestricted
  if (environment === 'prod') return 'us-east-1'
  if (environment === 'staging') return 'us-east-1'
  if (environment === 'local') return 'eu-central-1'
  return undefined
}

export const filterHighAvailabilityRegions = <T extends { code: string }>(
  regions: T[],
  highAvailability: boolean,
  environment = process.env.NEXT_PUBLIC_ENVIRONMENT
) => {
  const isLocal = environment === 'local'
  const regionCode = getHighAvailabilityRegionCode(environment)
  return highAvailability && !isLocal && regionCode !== undefined
    ? regions.filter((region) => region.code === regionCode)
    : regions
}

export type FreeTierGeneralRegionExperimentVariant = 'test' | 'control'

type GetFreeTierGeneralRegionExperimentVariantArgs = {
  isFreePlan: boolean
  smartRegionEnabled: boolean
  enrollmentFlag: boolean
  selectionFlag: boolean
}

/**
 * Org's arm in the freeTierGeneralRegionExperiment. The test arm only sees general regions.
 * Returns undefined when the org isn't enrolled.
 */
export function getFreeTierGeneralRegionExperimentVariant({
  isFreePlan,
  smartRegionEnabled,
  enrollmentFlag,
  selectionFlag,
}: GetFreeTierGeneralRegionExperimentVariantArgs):
  | FreeTierGeneralRegionExperimentVariant
  | undefined {
  const isInExperiment = isFreePlan && smartRegionEnabled && enrollmentFlag === true
  if (!isInExperiment) return undefined
  return selectionFlag === true ? 'test' : 'control'
}

export type AvailableRegions = NonNullable<OrganizationAvailableRegionsData>['all']

type GetRegionSelectionTypeArgs = {
  dbRegion: string | undefined
  availableRegions: AvailableRegions | undefined
}

/**
 * Whether the selected region is a general region (e.g. Americas) or a specific one
 * (e.g. us-east-1). Returns undefined if it matches neither list.
 */
export function getRegionSelectionType({
  dbRegion,
  availableRegions,
}: GetRegionSelectionTypeArgs): 'general' | 'specific' | undefined {
  if (!dbRegion || !availableRegions) return undefined
  if (availableRegions.smartGroup.some((region) => region.name === dbRegion)) return 'general'
  if (availableRegions.specific.some((region) => region.name === dbRegion)) return 'specific'
  return undefined
}