import { db } from '@sim/db'
import { invitation, member, organization, subscription, user } from '@sim/db/schema'
import { createLogger } from '@sim/logger'
import { normalizeEmail } from '@sim/utils/string'
import { and, count, eq, gt, ne } from 'drizzle-orm'
import { getOrganizationSubscription } from '@/lib/billing/core/billing'
import { isEnterprise, isFree } from '@/lib/billing/plan-helpers'
import { getEffectiveSeats } from '@/lib/billing/subscriptions/utils'
import { OUTBOX_EVENT_TYPES } from '@/lib/billing/webhooks/outbox-handlers'
import { isBillingEnabled } from '@/lib/core/config/env-flags'
import { hasInflightOutboxEvent } from '@/lib/core/outbox/service'
import { quickValidateEmail } from '@/lib/messaging/email/validation'

const logger = createLogger('SeatManagement')

interface SeatValidationResult {
  canInvite: boolean
  reason?: string
  currentSeats: number
  maxSeats: number
  availableSeats: number
}

interface OrganizationSeatInfo {
  organizationId: string
  organizationName: string
  currentSeats: number
  maxSeats: number
  availableSeats: number
  subscriptionPlan: string
  canAddSeats: boolean
}

interface ValidateSeatOptions {
  excludePendingInvitationId?: string
}

export async function validateSeatAvailability(
  organizationId: string,
  additionalSeats = 1,
  options: ValidateSeatOptions = {}
): Promise<SeatValidationResult> {
  try {
    if (!isBillingEnabled) {
      const memberCount = await db
        .select({ count: count() })
        .from(member)
        .where(eq(member.organizationId, organizationId))
      const currentSeats = memberCount[0]?.count || 0
      return {
        canInvite: true,
        currentSeats,
        maxSeats: Number.MAX_SAFE_INTEGER,
        availableSeats: Number.MAX_SAFE_INTEGER,
      }
    }

    const subscription = await getOrganizationSubscription(organizationId)

    if (!subscription) {
      return {
        canInvite: false,
        reason: 'No active subscription found',
        currentSeats: 0,
        maxSeats: 0,
        availableSeats: 0,
      }
    }

    if (isFree(subscription.plan)) {
      return {
        canInvite: false,
        reason: 'Organization features require a paid plan',
        currentSeats: 0,
        maxSeats: 0,
        availableSeats: 0,
      }
    }

    const [memberCount] = await db
      .select({ count: count() })
      .from(member)
      .where(eq(member.organizationId, organizationId))

    const pendingFilters = [
      eq(invitation.organizationId, organizationId),
      eq(invitation.status, 'pending'),
      ne(invitation.membershipIntent, 'external'),
      gt(invitation.expiresAt, new Date()),
    ]
    if (options.excludePendingInvitationId) {
      pendingFilters.push(ne(invitation.id, options.excludePendingInvitationId))
    }
    const [pendingCount] = await db
      .select({ count: count() })
      .from(invitation)
      .where(and(...pendingFilters))

    const currentSeats = (memberCount?.count ?? 0) + (pendingCount?.count ?? 0)

    const maxSeats = getEffectiveSeats(subscription)
    const availableSeats = Math.max(0, maxSeats - currentSeats)
    const canInvite = availableSeats >= additionalSeats

    const result: SeatValidationResult = {
      canInvite,
      currentSeats,
      maxSeats,
      availableSeats,
    }

    if (!canInvite) {
      if (additionalSeats === 1) {
        result.reason = `No available seats. Currently using ${currentSeats} of ${maxSeats} seats.`
      } else {
        result.reason = `Not enough available seats. Need ${additionalSeats} seats, but only ${availableSeats} available.`
      }
    }

    logger.debug('Seat validation result', {
      organizationId,
      additionalSeats,
      result,
    })

    return result
  } catch (error) {
    logger.error('Failed to validate seat availability', { organizationId, additionalSeats, error })
    return {
      canInvite: false,
      reason: 'Failed to check seat availability',
      currentSeats: 0,
      maxSeats: 0,
      availableSeats: 0,
    }
  }
}

/**
 * Get comprehensive seat information for an organization
 */
export async function getOrganizationSeatInfo(
  organizationId: string
): Promise<OrganizationSeatInfo | null> {
  try {
    const organizationData = await db
      .select({
        id: organization.id,
        name: organization.name,
      })
      .from(organization)
      .where(eq(organization.id, organizationId))
      .limit(1)

    if (organizationData.length === 0) {
      return null
    }

    const [memberCountRow] = await db
      .select({ count: count() })
      .from(member)
      .where(eq(member.organizationId, organizationId))

    const [pendingCountRow] = await db
      .select({ count: count() })
      .from(invitation)
      .where(
        and(
          eq(invitation.organizationId, organizationId),
          eq(invitation.status, 'pending'),
          ne(invitation.membershipIntent, 'external'),
          gt(invitation.expiresAt, new Date())
        )
      )

    const currentSeats = (memberCountRow?.count ?? 0) + (pendingCountRow?.count ?? 0)

    if (!isBillingEnabled) {
      return {
        organizationId,
        organizationName: organizationData[0].name,
        currentSeats,
        maxSeats: Number.MAX_SAFE_INTEGER,
        availableSeats: Number.MAX_SAFE_INTEGER,
        subscriptionPlan: 'billing_disabled',
        canAddSeats: false,
      }
    }

    const subscription = await getOrganizationSubscription(organizationId)

    if (!subscription) {
      return null
    }

    const maxSeats = getEffectiveSeats(subscription)

    const canAddSeats = !isEnterprise(subscription.plan)

    const availableSeats = Math.max(0, maxSeats - currentSeats)

    return {
      organizationId,
      organizationName: organizationData[0].name,
      currentSeats,
      maxSeats,
      availableSeats,
      subscriptionPlan: subscription.plan,
      canAddSeats,
    }
  } catch (error) {
    logger.error('Failed to get organization seat info', { organizationId, error })
    return null
  }
}

/**
 * Validate and reserve seats for bulk invitations
 */
export async function validateBulkInvitations(
  organizationId: string,
  emailList: string[]
): Promise<{
  canInviteAll: boolean
  validEmails: string[]
  duplicateEmails: string[]
  existingMembers: string[]
  seatsNeeded: number
  seatsAvailable: number
  validationResult: SeatValidationResult
}> {
  try {
    const uniqueEmails = [...new Set(emailList)]
    const validEmails = uniqueEmails.filter(
      (email) => quickValidateEmail(normalizeEmail(email)).isValid
    )
    const duplicateEmails = emailList.filter((email, index) => emailList.indexOf(email) !== index)

    const existingMembers = await db
      .select({ userEmail: user.email })
      .from(member)
      .innerJoin(user, eq(member.userId, user.id))
      .where(eq(member.organizationId, organizationId))

    const existingEmails = existingMembers.map((m) => m.userEmail)
    const newEmails = validEmails.filter((email) => !existingEmails.includes(email))

    const pendingInvitations = await db
      .select({ email: invitation.email })
      .from(invitation)
      .where(
        and(
          eq(invitation.organizationId, organizationId),
          eq(invitation.status, 'pending'),
          ne(invitation.membershipIntent, 'external'),
          gt(invitation.expiresAt, new Date())
        )
      )

    const pendingEmails = pendingInvitations.map((i) => i.email)
    const finalEmailsToInvite = newEmails.filter((email) => !pendingEmails.includes(email))

    const seatsNeeded = finalEmailsToInvite.length
    const validationResult = await validateSeatAvailability(organizationId, seatsNeeded)

    return {
      canInviteAll: validationResult.canInvite && finalEmailsToInvite.length > 0,
      validEmails: finalEmailsToInvite,
      duplicateEmails,
      existingMembers: validEmails.filter((email) => existingEmails.includes(email)),
      seatsNeeded,
      seatsAvailable: validationResult.availableSeats,
      validationResult,
    }
  } catch (error) {
    logger.error('Failed to validate bulk invitations', {
      organizationId,
      emailCount: emailList.length,
      error,
    })

    const validationResult: SeatValidationResult = {
      canInvite: false,
      reason: 'Validation failed',
      currentSeats: 0,
      maxSeats: 0,
      availableSeats: 0,
    }

    return {
      canInviteAll: false,
      validEmails: [],
      duplicateEmails: [],
      existingMembers: [],
      seatsNeeded: 0,
      seatsAvailable: 0,
      validationResult,
    }
  }
}

/**
 * Get seat usage analytics for an organization
 */
export async function getOrganizationSeatAnalytics(organizationId: string) {
  try {
    const seatInfo = await getOrganizationSeatInfo(organizationId)

    if (!seatInfo) {
      return null
    }

    const utilizationRate =
      seatInfo.maxSeats > 0 ? (seatInfo.currentSeats / seatInfo.maxSeats) * 100 : 0

    // Member activity analytics (active/inactive counts, memberActivity) were
    // derived from userStats.lastActive, which is no longer written. Dropped
    // rather than report frozen data; reintroduce with a real activity source.
    return {
      ...seatInfo,
      utilizationRate: Math.round(utilizationRate * 100) / 100,
    }
  } catch (error) {
    logger.error('Failed to get organization seat analytics', { organizationId, error })
    return null
  }
}

/**
 * Sync seat count from Stripe subscription quantity. Used by webhook handlers
 * to keep the local DB in sync with Stripe. No-ops while a DB→Stripe seat-sync
 * is still in flight for the subscription, so a stale webhook never clobbers a
 * DB seat change that hasn't been pushed yet (DB is the source of truth).
 */
export async function syncSeatsFromStripeQuantity(
  subscriptionId: string,
  currentSeats: number | null,
  stripeQuantity: number
): Promise<{ synced: boolean; previousSeats: number | null; newSeats: number }> {
  const effectiveCurrentSeats = currentSeats ?? 0

  // Only update if quantity differs
  if (stripeQuantity === effectiveCurrentSeats) {
    return {
      synced: false,
      previousSeats: effectiveCurrentSeats,
      newSeats: stripeQuantity,
    }
  }

  // The DB is the source of truth for Team seats; we push the DB value to
  // Stripe asynchronously via the seat-sync outbox. While that sync is still in
  // flight the DB is intentionally ahead of Stripe, so skip this Stripe-to-DB
  // sync — otherwise a stale customer.subscription.updated webhook could clobber
  // the not-yet-pushed value (e.g. revert a just-removed member's seat).
  const seatSyncInFlight = await hasInflightOutboxEvent(
    OUTBOX_EVENT_TYPES.STRIPE_SYNC_SUBSCRIPTION_SEATS,
    'subscriptionId',
    subscriptionId
  )
  if (seatSyncInFlight) {
    logger.info('Skipping Stripe seat sync; a seat-sync to Stripe is still in flight', {
      subscriptionId,
      stripeQuantity,
      currentSeats: effectiveCurrentSeats,
    })
    return {
      synced: false,
      previousSeats: effectiveCurrentSeats,
      newSeats: effectiveCurrentSeats,
    }
  }

  try {
    await db
      .update(subscription)
      .set({ seats: stripeQuantity })
      .where(eq(subscription.id, subscriptionId))

    logger.info('Synced seat count from Stripe', {
      subscriptionId,
      previousSeats: effectiveCurrentSeats,
      newSeats: stripeQuantity,
    })

    return {
      synced: true,
      previousSeats: effectiveCurrentSeats,
      newSeats: stripeQuantity,
    }
  } catch (error) {
    logger.error('Failed to sync seat count from Stripe', {
      subscriptionId,
      stripeQuantity,
      error,
    })
    throw error
  }
}