import { isSessionActive, resolveSessionDeadlines } from './session-policy'
import type { TokenDigester } from './token-digest'

export interface AuthUserRecord {
  id: string
  email: string
  displayName: string
  passwordHash: string
  emailVerified: boolean
  image: string | null
  status: 'active' | 'disabled' | 'pending_deletion'
  createdAt: Date
  updatedAt: Date
}

export interface AuthSessionRecord {
  id: string
  userId: string
  tokenHash: string
  createdAt: Date
  lastSeenAt: Date
  idleExpiresAt: Date
  absoluteExpiresAt: Date
  revokedAt: Date | null
  sourceIpHash: string | null
  userAgentSummary: string | null
}

export interface CreateAuthSessionRecord {
  userId: string
  tokenHash: string
  createdAt: Date
  lastSeenAt: Date
  idleExpiresAt: Date
  absoluteExpiresAt: Date
  sourceIpHash: string | null
  userAgentSummary: string | null
}

export interface AuthPersistence {
  findUserById(id: string): Promise<AuthUserRecord | null>
  findUserByEmail(email: string): Promise<AuthUserRecord | null>
  updateUser(
    id: string,
    update: Partial<
      Pick<
        AuthUserRecord,
        'displayName' | 'email' | 'emailVerified' | 'image' | 'passwordHash'
      >
    >,
  ): Promise<AuthUserRecord | null>
  createSession(input: CreateAuthSessionRecord): Promise<AuthSessionRecord>
  findSessionByTokenHash(tokenHash: string): Promise<AuthSessionRecord | null>
  touchSession(
    id: string,
    input: { lastSeenAt: Date; idleExpiresAt: Date },
  ): Promise<AuthSessionRecord | null>
  revokeSessionByTokenHash(tokenHash: string, revokedAt: Date): Promise<boolean>
  revokeSessionsForUser(userId: string, revokedAt: Date): Promise<number>
}

export interface ActiveAuthSession {
  session: AuthSessionRecord
  user: AuthUserRecord
  rawToken: string
}

export class AuthService {
  constructor(
    private readonly persistence: AuthPersistence,
    private readonly digester: TokenDigester,
    private readonly now: () => Date = () => new Date(),
  ) {}

  findUserById(id: string) {
    return this.persistence.findUserById(id)
  }

  findUserByEmail(email: string) {
    return this.persistence.findUserByEmail(email.trim().toLowerCase())
  }

  updateUser(
    id: string,
    update: Partial<
      Pick<
        AuthUserRecord,
        'displayName' | 'email' | 'emailVerified' | 'image' | 'passwordHash'
      >
    >,
  ) {
    return this.persistence.updateUser(id, update)
  }

  async createSession(input: {
    userId: string
    rawToken: string
    sourceIpHash?: string | null
    userAgentSummary?: string | null
  }): Promise<ActiveAuthSession | null> {
    const user = await this.persistence.findUserById(input.userId)
    if (!user || user.status !== 'active') return null
    const now = this.now()
    const deadlines = resolveSessionDeadlines({ createdAt: now, now })
    const session = await this.persistence.createSession({
      userId: user.id,
      tokenHash: this.digester.digest(input.rawToken),
      createdAt: now,
      lastSeenAt: now,
      ...deadlines,
      sourceIpHash: input.sourceIpHash ?? null,
      userAgentSummary: input.userAgentSummary ?? null,
    })
    return { session, user, rawToken: input.rawToken }
  }

  async findActiveSession(rawToken: string): Promise<ActiveAuthSession | null> {
    const now = this.now()
    const session = await this.persistence.findSessionByTokenHash(
      this.digester.digest(rawToken),
    )
    if (!session || !isSessionActive(now, session)) return null
    const user = await this.persistence.findUserById(session.userId)
    if (!user || user.status !== 'active') return null
    const deadlines = resolveSessionDeadlines({
      createdAt: session.createdAt,
      now,
      absoluteExpiresAt: session.absoluteExpiresAt,
    })
    const touched = await this.persistence.touchSession(session.id, {
      lastSeenAt: now,
      idleExpiresAt: deadlines.idleExpiresAt,
    })
    if (!touched) return null
    return { session: touched, user, rawToken }
  }

  revokeSession(rawToken: string): Promise<boolean> {
    return this.persistence.revokeSessionByTokenHash(
      this.digester.digest(rawToken),
      this.now(),
    )
  }

  revokeSessionsForUser(userId: string): Promise<number> {
    return this.persistence.revokeSessionsForUser(userId, this.now())
  }
}