import { createSign } from 'crypto'
import { db } from '@sim/db'
import { account, credential, credentialSetMember } from '@sim/db/schema'
import { createLogger } from '@sim/logger'
import { and, desc, eq, inArray } from 'drizzle-orm'
import { decryptSecret } from '@/lib/core/security/encryption'
import { refreshOAuthToken } from '@/lib/oauth'
import {
  getMicrosoftRefreshTokenExpiry,
  isMicrosoftProvider,
  PROACTIVE_REFRESH_THRESHOLD_DAYS,
} from '@/lib/oauth/microsoft'

const logger = createLogger('OAuthUtilsAPI')

export class ServiceAccountTokenError extends Error {
  constructor(
    public readonly statusCode: number,
    public readonly errorDescription: string
  ) {
    super(errorDescription)
    this.name = 'ServiceAccountTokenError'
  }
}

interface AccountInsertData {
  id: string
  userId: string
  providerId: string
  accountId: string
  accessToken: string
  scope: string
  createdAt: Date
  updatedAt: Date
  refreshToken?: string
  idToken?: string
  accessTokenExpiresAt?: Date
}

export interface ResolvedCredential {
  accountId: string
  workspaceId?: string
  usedCredentialTable: boolean
  credentialType?: string
  credentialId?: string
}

/**
 * Resolves a credential ID to its underlying account ID.
 * If `credentialId` matches a `credential` row, returns its `accountId` and `workspaceId`.
 * For service_account credentials, returns credentialId and type instead of accountId.
 * Otherwise assumes `credentialId` is already a raw `account.id` (legacy).
 */
export async function resolveOAuthAccountId(
  credentialId: string
): Promise<ResolvedCredential | null> {
  const [credentialRow] = await db
    .select({
      id: credential.id,
      type: credential.type,
      accountId: credential.accountId,
      workspaceId: credential.workspaceId,
    })
    .from(credential)
    .where(eq(credential.id, credentialId))
    .limit(1)

  if (credentialRow) {
    if (credentialRow.type === 'service_account') {
      return {
        accountId: '',
        credentialId: credentialRow.id,
        credentialType: 'service_account',
        workspaceId: credentialRow.workspaceId,
        usedCredentialTable: true,
      }
    }

    if (credentialRow.type !== 'oauth' || !credentialRow.accountId) {
      return null
    }
    return {
      accountId: credentialRow.accountId,
      workspaceId: credentialRow.workspaceId,
      usedCredentialTable: true,
    }
  }

  return { accountId: credentialId, usedCredentialTable: false }
}

/**
 * Userinfo scopes are excluded because service accounts don't represent a user
 * and cannot request user identity information. Google rejects token requests
 * that include these scopes for service account credentials.
 */
const SA_EXCLUDED_SCOPES = new Set([
  'https://www.googleapis.com/auth/userinfo.email',
  'https://www.googleapis.com/auth/userinfo.profile',
])

/**
 * Generates a short-lived access token for a Google service account credential
 * using the two-legged OAuth JWT flow (RFC 7523).
 *
 * @param impersonateEmail - Optional. Required for Google Workspace APIs (Gmail, Drive, Calendar, etc.)
 *   where the service account must impersonate a domain user via domain-wide delegation.
 *   Not needed for project-scoped APIs like BigQuery or Vertex AI where the service account
 *   authenticates directly with its own IAM permissions.
 */
export async function getServiceAccountToken(
  credentialId: string,
  scopes: string[],
  impersonateEmail?: string
): Promise<string> {
  const [credentialRow] = await db
    .select({
      encryptedServiceAccountKey: credential.encryptedServiceAccountKey,
    })
    .from(credential)
    .where(eq(credential.id, credentialId))
    .limit(1)

  if (!credentialRow?.encryptedServiceAccountKey) {
    throw new Error('Service account key not found')
  }

  const { decrypted } = await decryptSecret(credentialRow.encryptedServiceAccountKey)
  const keyData = JSON.parse(decrypted) as {
    client_email: string
    private_key: string
    token_uri?: string
  }

  const filteredScopes = scopes.filter((s) => !SA_EXCLUDED_SCOPES.has(s))

  const now = Math.floor(Date.now() / 1000)
  const ALLOWED_TOKEN_URIS = new Set(['https://oauth2.googleapis.com/token'])
  const tokenUri =
    keyData.token_uri && ALLOWED_TOKEN_URIS.has(keyData.token_uri)
      ? keyData.token_uri
      : 'https://oauth2.googleapis.com/token'

  const header = { alg: 'RS256', typ: 'JWT' }
  const payload: Record<string, unknown> = {
    iss: keyData.client_email,
    scope: filteredScopes.join(' '),
    aud: tokenUri,
    iat: now,
    exp: now + 3600,
  }

  if (impersonateEmail) {
    payload.sub = impersonateEmail
  }

  logger.info('Service account JWT payload', {
    iss: keyData.client_email,
    sub: impersonateEmail || '(none)',
    scopes: filteredScopes.join(' '),
    aud: tokenUri,
  })

  const toBase64Url = (obj: unknown) => Buffer.from(JSON.stringify(obj)).toString('base64url')

  const signingInput = `${toBase64Url(header)}.${toBase64Url(payload)}`

  const signer = createSign('RSA-SHA256')
  signer.update(signingInput)
  const signature = signer.sign(keyData.private_key, 'base64url')

  const jwt = `${signingInput}.${signature}`

  const response = await fetch(tokenUri, {
    method: 'POST',
    headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
    body: new URLSearchParams({
      grant_type: 'urn:ietf:params:oauth:grant-type:jwt-bearer',
      assertion: jwt,
    }),
  })

  if (!response.ok) {
    const errorBody = await response.text()
    logger.error('Service account token exchange failed', {
      status: response.status,
      body: errorBody,
    })
    let description = `Token exchange failed: ${response.status}`
    try {
      const parsed = JSON.parse(errorBody) as { error_description?: string }
      if (parsed.error_description) {
        const raw = parsed.error_description
        if (raw.includes('SignatureException') || raw.includes('Invalid signature')) {
          description = 'Invalid account credentials.'
        } else {
          description = raw
        }
      }
    } catch {
      // use default description
    }
    throw new ServiceAccountTokenError(response.status, description)
  }

  const tokenData = (await response.json()) as { access_token: string }
  return tokenData.access_token
}

/**
 * Safely inserts an account record, handling duplicate constraint violations gracefully.
 * If a duplicate is detected (unique constraint violation), logs a warning and returns success.
 */
export async function safeAccountInsert(
  data: AccountInsertData,
  context: { provider: string; identifier?: string }
): Promise<void> {
  try {
    await db.insert(account).values(data)
    logger.info(`Created new ${context.provider} account for user`, { userId: data.userId })
  } catch (error: any) {
    if (error?.code === '23505') {
      logger.error(`Duplicate ${context.provider} account detected, credential already exists`, {
        userId: data.userId,
        identifier: context.identifier,
      })
    } else {
      throw error
    }
  }
}

/**
 * Get a credential by resolved account ID and verify it belongs to the user.
 */
async function getCredentialByAccountId(requestId: string, accountId: string, userId: string) {
  const credentials = await db
    .select()
    .from(account)
    .where(and(eq(account.id, accountId), eq(account.userId, userId)))
    .limit(1)

  if (!credentials.length) {
    logger.warn(`[${requestId}] Credential not found`)
    return undefined
  }

  return {
    ...credentials[0],
    resolvedCredentialId: accountId,
  }
}

/**
 * Get a credential by ID and verify it belongs to the user.
 */
export async function getCredential(requestId: string, credentialId: string, userId: string) {
  const resolved = await resolveOAuthAccountId(credentialId)
  if (!resolved) {
    logger.warn(`[${requestId}] Credential is not an OAuth credential`)
    return undefined
  }
  return getCredentialByAccountId(requestId, resolved.accountId, userId)
}

export async function getOAuthToken(userId: string, providerId: string): Promise<string | null> {
  const connections = await db
    .select({
      id: account.id,
      accessToken: account.accessToken,
      refreshToken: account.refreshToken,
      accessTokenExpiresAt: account.accessTokenExpiresAt,
      idToken: account.idToken,
      scope: account.scope,
    })
    .from(account)
    .where(and(eq(account.userId, userId), eq(account.providerId, providerId)))
    .orderBy(desc(account.updatedAt))
    .limit(1)

  if (connections.length === 0) {
    logger.warn(`No OAuth token found for user ${userId}, provider ${providerId}`)
    return null
  }

  const credential = connections[0]

  // Determine whether we should refresh: missing token OR expired token
  const now = new Date()
  const tokenExpiry = credential.accessTokenExpiresAt
  const shouldAttemptRefresh =
    !!credential.refreshToken && (!credential.accessToken || (tokenExpiry && tokenExpiry < now))

  if (shouldAttemptRefresh) {
    logger.info(
      `Access token expired for user ${userId}, provider ${providerId}. Attempting to refresh.`
    )

    try {
      // Use the existing refreshOAuthToken function
      const refreshResult = await refreshOAuthToken(providerId, credential.refreshToken!)

      if (!refreshResult) {
        logger.error(`Failed to refresh token for user ${userId}, provider ${providerId}`, {
          providerId,
          userId,
          hasRefreshToken: !!credential.refreshToken,
        })
        return null
      }

      const { accessToken, expiresIn, refreshToken: newRefreshToken } = refreshResult

      // Update the database with new tokens
      const updateData: any = {
        accessToken,
        accessTokenExpiresAt: new Date(Date.now() + expiresIn * 1000), // Convert seconds to milliseconds
        updatedAt: new Date(),
      }

      // If we received a new refresh token (some providers like Airtable rotate them), save it
      if (newRefreshToken && newRefreshToken !== credential.refreshToken) {
        logger.info(`Updating refresh token for user ${userId}, provider ${providerId}`)
        updateData.refreshToken = newRefreshToken
      }

      // Update the token in the database with the actual expiration time from the provider
      await db.update(account).set(updateData).where(eq(account.id, credential.id))

      logger.info(`Successfully refreshed token for user ${userId}, provider ${providerId}`)
      return accessToken
    } catch (error) {
      logger.error(`Error refreshing token for user ${userId}, provider ${providerId}`, {
        error: error instanceof Error ? error.message : String(error),
        stack: error instanceof Error ? error.stack : undefined,
        providerId,
        userId,
      })
      return null
    }
  }

  if (!credential.accessToken) {
    logger.warn(
      `Access token is null and no refresh attempted or available for user ${userId}, provider ${providerId}`
    )
    return null
  }

  logger.info(`Found valid OAuth token for user ${userId}, provider ${providerId}`)
  return credential.accessToken
}

/**
 * Refreshes an OAuth token if needed based on credential information.
 * Also handles service account credentials by generating a JWT-based token.
 * @param credentialId The ID of the credential to check and potentially refresh
 * @param userId The user ID who owns the credential (for security verification)
 * @param requestId Request ID for log correlation
 * @param scopes Optional scopes for service account token generation
 * @returns The valid access token or null if refresh fails
 */
export async function refreshAccessTokenIfNeeded(
  credentialId: string,
  userId: string,
  requestId: string,
  scopes?: string[],
  impersonateEmail?: string
): Promise<string | null> {
  const resolved = await resolveOAuthAccountId(credentialId)
  if (!resolved) {
    return null
  }

  if (resolved.credentialType === 'service_account' && resolved.credentialId) {
    if (!scopes?.length) {
      throw new Error('Scopes are required for service account credentials')
    }
    logger.info(`[${requestId}] Using service account token for credential`)
    return getServiceAccountToken(resolved.credentialId, scopes, impersonateEmail)
  }

  // Use the already-resolved account ID to avoid a redundant resolveOAuthAccountId query
  const credential = await getCredentialByAccountId(requestId, resolved.accountId, userId)

  if (!credential) {
    return null
  }

  // Decide if we should refresh: token missing OR expired
  const accessTokenExpiresAt = credential.accessTokenExpiresAt
  const refreshTokenExpiresAt = credential.refreshTokenExpiresAt
  const now = new Date()

  // Check if access token needs refresh (missing or expired)
  const accessTokenNeedsRefresh =
    !!credential.refreshToken &&
    (!credential.accessToken || (accessTokenExpiresAt && accessTokenExpiresAt <= now))

  // Check if we should proactively refresh to prevent refresh token expiry
  // This applies to Microsoft providers whose refresh tokens expire after 90 days of inactivity
  const proactiveRefreshThreshold = new Date(
    now.getTime() + PROACTIVE_REFRESH_THRESHOLD_DAYS * 24 * 60 * 60 * 1000
  )
  const refreshTokenNeedsProactiveRefresh =
    !!credential.refreshToken &&
    isMicrosoftProvider(credential.providerId) &&
    refreshTokenExpiresAt &&
    refreshTokenExpiresAt <= proactiveRefreshThreshold

  const shouldRefresh = accessTokenNeedsRefresh || refreshTokenNeedsProactiveRefresh

  const accessToken = credential.accessToken

  if (shouldRefresh) {
    logger.info(`[${requestId}] Refreshing token for credential`)
    try {
      const refreshedToken = await refreshOAuthToken(
        credential.providerId,
        credential.refreshToken!
      )

      if (!refreshedToken) {
        logger.error(`[${requestId}] Failed to refresh token for credential: ${credentialId}`, {
          credentialId,
          providerId: credential.providerId,
          userId: credential.userId,
          hasRefreshToken: !!credential.refreshToken,
        })
        if (!accessTokenNeedsRefresh && accessToken) {
          logger.info(`[${requestId}] Proactive refresh failed but access token still valid`)
          return accessToken
        }
        return null
      }

      // Prepare update data
      const updateData: Record<string, unknown> = {
        accessToken: refreshedToken.accessToken,
        accessTokenExpiresAt: new Date(Date.now() + refreshedToken.expiresIn * 1000),
        updatedAt: new Date(),
      }

      // If we received a new refresh token, update it
      if (refreshedToken.refreshToken && refreshedToken.refreshToken !== credential.refreshToken) {
        logger.info(`[${requestId}] Updating refresh token for credential`)
        updateData.refreshToken = refreshedToken.refreshToken
      }

      if (isMicrosoftProvider(credential.providerId)) {
        updateData.refreshTokenExpiresAt = getMicrosoftRefreshTokenExpiry()
      }

      // Update the token in the database
      const resolvedCredentialId =
        (credential as { resolvedCredentialId?: string }).resolvedCredentialId ?? credentialId
      await db.update(account).set(updateData).where(eq(account.id, resolvedCredentialId))

      logger.info(`[${requestId}] Successfully refreshed access token for credential`)
      return refreshedToken.accessToken
    } catch (error) {
      logger.error(`[${requestId}] Error refreshing token for credential`, {
        error: error instanceof Error ? error.message : String(error),
        stack: error instanceof Error ? error.stack : undefined,
        providerId: credential.providerId,
        credentialId,
        userId: credential.userId,
      })
      if (!accessTokenNeedsRefresh && accessToken) {
        logger.info(`[${requestId}] Proactive refresh failed but access token still valid`)
        return accessToken
      }
      return null
    }
  } else if (!accessToken) {
    // We have no access token and either no refresh token or not eligible to refresh
    logger.error(`[${requestId}] Missing access token for credential`)
    return null
  }

  logger.info(`[${requestId}] Access token is valid for credential`)
  return accessToken
}

/**
 * Enhanced version that returns additional information about the refresh operation
 */
export async function refreshTokenIfNeeded(
  requestId: string,
  credential: any,
  credentialId: string
): Promise<{ accessToken: string; refreshed: boolean }> {
  const resolvedCredentialId = credential.resolvedCredentialId ?? credentialId

  // Decide if we should refresh: token missing OR expired
  const accessTokenExpiresAt = credential.accessTokenExpiresAt
  const refreshTokenExpiresAt = credential.refreshTokenExpiresAt
  const now = new Date()

  // Check if access token needs refresh (missing or expired)
  const accessTokenNeedsRefresh =
    !!credential.refreshToken &&
    (!credential.accessToken || (accessTokenExpiresAt && accessTokenExpiresAt <= now))

  // Check if we should proactively refresh to prevent refresh token expiry
  // This applies to Microsoft providers whose refresh tokens expire after 90 days of inactivity
  const proactiveRefreshThreshold = new Date(
    now.getTime() + PROACTIVE_REFRESH_THRESHOLD_DAYS * 24 * 60 * 60 * 1000
  )
  const refreshTokenNeedsProactiveRefresh =
    !!credential.refreshToken &&
    isMicrosoftProvider(credential.providerId) &&
    refreshTokenExpiresAt &&
    refreshTokenExpiresAt <= proactiveRefreshThreshold

  const shouldRefresh = accessTokenNeedsRefresh || refreshTokenNeedsProactiveRefresh

  // If token appears valid and present, return it directly
  if (!shouldRefresh) {
    logger.info(`[${requestId}] Access token is valid`)
    return { accessToken: credential.accessToken, refreshed: false }
  }

  try {
    const refreshResult = await refreshOAuthToken(credential.providerId, credential.refreshToken!)

    if (!refreshResult) {
      logger.error(`[${requestId}] Failed to refresh token for credential`)
      if (!accessTokenNeedsRefresh && credential.accessToken) {
        logger.info(`[${requestId}] Proactive refresh failed but access token still valid`)
        return { accessToken: credential.accessToken, refreshed: false }
      }
      throw new Error('Failed to refresh token')
    }

    const { accessToken: refreshedToken, expiresIn, refreshToken: newRefreshToken } = refreshResult

    // Prepare update data
    const updateData: Record<string, unknown> = {
      accessToken: refreshedToken,
      accessTokenExpiresAt: new Date(Date.now() + expiresIn * 1000), // Use provider's expiry
      updatedAt: new Date(),
    }

    // If we received a new refresh token, update it
    if (newRefreshToken && newRefreshToken !== credential.refreshToken) {
      logger.info(`[${requestId}] Updating refresh token`)
      updateData.refreshToken = newRefreshToken
    }

    if (isMicrosoftProvider(credential.providerId)) {
      updateData.refreshTokenExpiresAt = getMicrosoftRefreshTokenExpiry()
    }

    await db.update(account).set(updateData).where(eq(account.id, resolvedCredentialId))

    logger.info(`[${requestId}] Successfully refreshed access token`)
    return { accessToken: refreshedToken, refreshed: true }
  } catch (error) {
    logger.warn(
      `[${requestId}] Refresh attempt failed, checking if another concurrent request succeeded`
    )

    const freshCredential = await getCredential(requestId, resolvedCredentialId, credential.userId)
    if (freshCredential?.accessToken) {
      const freshExpiresAt = freshCredential.accessTokenExpiresAt
      const stillValid = !freshExpiresAt || freshExpiresAt > new Date()

      if (stillValid) {
        logger.info(`[${requestId}] Found valid token from concurrent refresh, using it`)
        return { accessToken: freshCredential.accessToken, refreshed: true }
      }
    }

    if (!accessTokenNeedsRefresh && credential.accessToken) {
      logger.info(`[${requestId}] Proactive refresh failed but access token still valid`)
      return { accessToken: credential.accessToken, refreshed: false }
    }

    logger.error(`[${requestId}] Refresh failed and no valid token found in DB`, error)
    throw error
  }
}

export interface CredentialSetCredential {
  userId: string
  credentialId: string
  accessToken: string
  providerId: string
}

export async function getCredentialsForCredentialSet(
  credentialSetId: string,
  providerId: string
): Promise<CredentialSetCredential[]> {
  logger.info(`Getting credentials for credential set ${credentialSetId}, provider ${providerId}`)

  const members = await db
    .select({ userId: credentialSetMember.userId })
    .from(credentialSetMember)
    .where(
      and(
        eq(credentialSetMember.credentialSetId, credentialSetId),
        eq(credentialSetMember.status, 'active')
      )
    )

  logger.info(`Found ${members.length} active members in credential set ${credentialSetId}`)

  if (members.length === 0) {
    logger.warn(`No active members found for credential set ${credentialSetId}`)
    return []
  }

  const userIds = members.map((m) => m.userId)
  logger.debug(`Member user IDs: ${userIds.join(', ')}`)

  const credentials = await db
    .select({
      id: account.id,
      userId: account.userId,
      providerId: account.providerId,
      accessToken: account.accessToken,
      refreshToken: account.refreshToken,
      accessTokenExpiresAt: account.accessTokenExpiresAt,
    })
    .from(account)
    .where(and(inArray(account.userId, userIds), eq(account.providerId, providerId)))

  logger.info(
    `Found ${credentials.length} credentials with provider ${providerId} for ${members.length} members`
  )

  const results: CredentialSetCredential[] = []

  for (const cred of credentials) {
    const now = new Date()
    const tokenExpiry = cred.accessTokenExpiresAt
    const shouldRefresh =
      !!cred.refreshToken && (!cred.accessToken || (tokenExpiry && tokenExpiry < now))

    let accessToken = cred.accessToken

    if (shouldRefresh && cred.refreshToken) {
      try {
        const refreshResult = await refreshOAuthToken(providerId, cred.refreshToken)

        if (refreshResult) {
          accessToken = refreshResult.accessToken

          const updateData: Record<string, unknown> = {
            accessToken: refreshResult.accessToken,
            accessTokenExpiresAt: new Date(Date.now() + refreshResult.expiresIn * 1000),
            updatedAt: new Date(),
          }

          if (refreshResult.refreshToken && refreshResult.refreshToken !== cred.refreshToken) {
            updateData.refreshToken = refreshResult.refreshToken
          }

          await db.update(account).set(updateData).where(eq(account.id, cred.id))

          logger.info(`Refreshed token for user ${cred.userId}, provider ${providerId}`)
        }
      } catch (error) {
        logger.error(`Failed to refresh token for user ${cred.userId}, provider ${providerId}`, {
          error: error instanceof Error ? error.message : String(error),
        })
        continue
      }
    }

    if (accessToken) {
      results.push({
        userId: cred.userId,
        credentialId: cred.id,
        accessToken,
        providerId,
      })
    }
  }

  logger.info(
    `Found ${results.length} valid credentials for credential set ${credentialSetId}, provider ${providerId}`
  )

  return results
}
