import { useFlag, useParams } from 'common'
import { UseFormReturn } from 'react-hook-form'
import type { CloudProvider } from 'shared-data'
import {
  Badge,
  cn,
  FormField,
  Select,
  SelectContent,
  SelectGroup,
  SelectItem,
  SelectLabel,
  SelectSeparator,
  SelectTrigger,
  SelectValue,
  Tooltip,
  TooltipContent,
  TooltipTrigger,
} from 'ui'
import { Admonition } from 'ui-patterns/admonition'
import { FormItemLayout } from 'ui-patterns/form/FormItemLayout/FormItemLayout'

import { CreateProjectForm } from './ProjectCreation.schema'
import { getAvailableRegions } from './ProjectCreation.utils'
import AlertError from '@/components/ui/AlertError'
import { InlineLink } from '@/components/ui/InlineLink'
import Panel from '@/components/ui/Panel'
import { useDefaultRegionQuery } from '@/data/misc/get-default-region-query'
import { useOrganizationAvailableRegionsQuery } from '@/data/organizations/organization-available-regions-query'
import { useIncidentStatusQuery } from '@/data/platform/incident-status-query'
import type { DesiredInstanceSize } from '@/data/projects/new-project.constants'
import { BASE_PATH, PROVIDERS } from '@/lib/constants'

interface RegionSelectorProps {
  form: UseFormReturn<CreateProjectForm>
  instanceSize?: DesiredInstanceSize
  layout?: 'vertical' | 'horizontal'
}

// [Joshen] Let's use a library to maintain the flag SVGs in the future
// I tried using https://flagpack.xyz/docs/development/react/ but couldn't get it to render
// ^ can try again next time

// Maps smart region group codes to the specific-region code prefixes they contain.
// Used to check whether an incident affecting specific regions also affects a smart region selection.
const SMART_REGION_PREFIXES: Record<string, Array<string>> = {
  americas: ['us-', 'ca-', 'sa-'],
  emea: ['eu-', 'me-', 'af-'],
  apac: ['ap-'],
}

function smartRegionMatchesSpecific(smartCode: string, specificCode: string): boolean {
  return (SMART_REGION_PREFIXES[smartCode] ?? []).some((prefix) => specificCode.startsWith(prefix))
}

// Map backend region names to user-friendly display names
const getDisplayNameForSmartRegion = (name: string): string => {
  if (name === 'APAC') {
    return 'Asia-Pacific'
  }
  return name
}

export const RegionSelector = ({
  form,
  instanceSize,
  layout = 'horizontal',
}: RegionSelectorProps) => {
  const { slug } = useParams()
  const cloudProvider = form.getValues('cloudProvider') as CloudProvider

  const smartRegionEnabled = useFlag('enableSmartRegion')

  const { data: statusData } = useIncidentStatusQuery()
  const { incidents = [] } = statusData ?? {}

  const { isPending: isLoadingDefaultRegion } = useDefaultRegionQuery(
    { cloudProvider },
    { enabled: !smartRegionEnabled }
  )

  const {
    data: availableRegionsData,
    isPending: isLoadingAvailableRegions,
    isError: isErrorAvailableRegions,
    error: errorAvailableRegions,
  } = useOrganizationAvailableRegionsQuery(
    { slug, cloudProvider, desiredInstanceSize: instanceSize },
    { enabled: smartRegionEnabled, staleTime: 1000 * 60 * 5 } // 5 minutes
  )

  const smartRegions = availableRegionsData?.all.smartGroup ?? []
  const allRegions = availableRegionsData?.all.specific ?? []

  const recommendedSmartRegions = new Set(
    [availableRegionsData?.recommendations.smartGroup.code].filter(Boolean)
  )
  const recommendedSpecificRegions = new Set(
    availableRegionsData?.recommendations.specific.map((region) => region.code)
  )

  const availableRegions = getAvailableRegions(PROVIDERS[cloudProvider].id)
  const regionsArray = Object.entries(availableRegions).map(([_key, value]) => {
    return {
      code: value.code,
      name: value.displayName,
      provider: cloudProvider,
      status: undefined,
    }
  })

  const regionOptions = smartRegionEnabled ? allRegions : regionsArray
  const isLoading = smartRegionEnabled ? isLoadingAvailableRegions : isLoadingDefaultRegion

  const showNonProdFields =
    process.env.NEXT_PUBLIC_ENVIRONMENT === 'local' ||
    process.env.NEXT_PUBLIC_ENVIRONMENT === 'staging'

  const allSelectableRegions = [...smartRegions, ...regionOptions]

  if (isErrorAvailableRegions) {
    return <AlertError subject="Error loading available regions" error={errorAvailableRegions} />
  }

  return (
    <Panel.Content>
      <FormField
        control={form.control}
        name="dbRegion"
        render={({ field }) => {
          const selectedRegion = allSelectableRegions.find((region) => {
            return !!region.name && region.name === field.value
          })

          const affectingIncidents = incidents.filter((incident) => {
            const affectedRegions = incident.cache?.affected_regions ?? []
            if (affectedRegions.length === 0 || selectedRegion?.code === undefined) return false

            // Specific region: direct code match
            if (affectedRegions.includes(selectedRegion.code)) return true

            // Smart region: match if any affected region falls within the smart group
            return affectedRegions.some((specificCode) =>
              smartRegionMatchesSpecific(selectedRegion.code, specificCode)
            )
          })

          return (
            <>
              <FormItemLayout
                layout={layout}
                label="Region"
                description={
                  <>
                    <p>Select the region closest to your users for the best performance.</p>
                    {showNonProdFields && (
                      <div className="mt-2 text-warning">
                        <p>Only these regions are supported for local/staging projects:</p>
                        <ul className="list-disc list-inside mt-1">
                          <li>East US (North Virginia)</li>
                          <li>Central EU (Frankfurt)</li>
                          <li>Southeast Asia (Singapore)</li>
                        </ul>
                      </div>
                    )}
                  </>
                }
              >
                <Select value={field.value} onValueChange={field.onChange} disabled={isLoading}>
                  <SelectTrigger className="[&>:nth-child(1)]:w-full [&>:nth-child(1)]:flex [&>:nth-child(1)]:items-start">
                    <SelectValue
                      placeholder={
                        isLoading
                          ? 'Loading available regions...'
                          : 'Select a region for your project..'
                      }
                    >
                      {field.value !== undefined && (
                        <div className="flex items-center gap-x-3">
                          {selectedRegion?.code && (
                            <img
                              alt="region icon"
                              className="w-5 rounded-xs"
                              src={`${BASE_PATH}/img/regions/${selectedRegion.code}.svg`}
                            />
                          )}
                          <span className="text-foreground">
                            {selectedRegion?.name
                              ? getDisplayNameForSmartRegion(selectedRegion.name)
                              : field.value}
                          </span>
                        </div>
                      )}
                    </SelectValue>
                  </SelectTrigger>
                  <SelectContent>
                    {smartRegionEnabled && (
                      <>
                        <SelectGroup>
                          <SelectLabel>General regions</SelectLabel>
                          {smartRegions.map((value) => {
                            return (
                              <SelectItem
                                key={value.code}
                                value={value.name}
                                className="w-full [&>:nth-child(2)]:w-full"
                              >
                                <div className="flex flex-row items-center justify-between w-full">
                                  <div className="flex items-center gap-x-3">
                                    <img
                                      alt="region icon"
                                      className="w-5 rounded-xs"
                                      src={`${BASE_PATH}/img/regions/${value.code}.svg`}
                                    />
                                    <span className="text-foreground">
                                      {getDisplayNameForSmartRegion(value.name)}
                                    </span>
                                  </div>

                                  <div>
                                    {recommendedSmartRegions.has(value.code) && (
                                      <Badge variant="success" className="mr-1">
                                        Recommended
                                      </Badge>
                                    )}
                                  </div>
                                </div>
                              </SelectItem>
                            )
                          })}
                        </SelectGroup>
                        <SelectSeparator />
                      </>
                    )}

                    <SelectGroup>
                      <SelectLabel>Specific regions</SelectLabel>
                      {regionOptions.map((value) => {
                        return (
                          <SelectItem
                            key={value.code}
                            value={value.name}
                            className={cn(
                              'w-full [&>:nth-child(2)]:w-full',
                              value.status !== undefined && 'pointer-events-auto!'
                            )}
                            disabled={value.status !== undefined}
                          >
                            <div className="flex flex-row items-center justify-between w-full gap-x-2">
                              <div className="flex items-center gap-x-3">
                                <img
                                  alt="region icon"
                                  className="w-5 rounded-xs"
                                  src={`${BASE_PATH}/img/regions/${value.code}.svg`}
                                />
                                <div className="flex items-center gap-x-2">
                                  <span className="text-foreground">{value.name}</span>
                                  <span className="text-xs text-foreground-lighter font-mono">
                                    {value.code}
                                  </span>
                                </div>
                              </div>

                              {recommendedSpecificRegions.has(value.code) && (
                                <Badge variant="success" className="mr-1">
                                  Recommended
                                </Badge>
                              )}
                              {value.status !== undefined && value.status === 'capacity' && (
                                <Tooltip>
                                  <TooltipTrigger>
                                    <Badge variant="warning" className="mr-1">
                                      Unavailable
                                    </Badge>
                                  </TooltipTrigger>
                                  <TooltipContent>
                                    Temporarily unavailable due to this region being at capacity.
                                  </TooltipContent>
                                </Tooltip>
                              )}
                            </div>
                          </SelectItem>
                        )
                      })}
                    </SelectGroup>
                  </SelectContent>
                </Select>
              </FormItemLayout>

              {affectingIncidents.length > 0 && (
                <FormItemLayout layout="horizontal">
                  <Admonition
                    type="warning"
                    title="Incident in progress for this region"
                    description={
                      <>
                        We're currently investigating an issue that may impact projects in this
                        region. Follow updates on{' '}
                        <InlineLink href="https://status.supabase.com">
                          status.supabase.com
                        </InlineLink>
                        .
                      </>
                    }
                    className="mt-3"
                  />
                </FormItemLayout>
              )}
            </>
          )
        }}
      />
    </Panel.Content>
  )
}