import { mkdirSync, readFileSync, writeFileSync } from "node:fs";
import { dirname, join } from "node:path";

import { app } from "electron/main";
import type { DesktopAccountInfo } from "@geo/shared-types";

import type {
  AccountAuthReason,
  AccountAuthState,
  AccountHealthProfile,
  AccountHealthSnapshot,
  AccountProbeState,
  AuthProbeResult,
  PlatformFailureClassification,
} from "./auth-types";
import { emitRuntimeInvalidated } from "./runtime-events";
import { getPersistedPartition, getSessionHandle } from "./session-registry";
import {
  getPlatformAdapter,
  type PlatformFailureInput,
} from "./platform-auth-adapters";
import type { PublishAccountIdentity } from "./account-binder";

const PROBE_TICK_MS = 10_000;
const FIRST_PROBE_MIN_MS = 5_000;
const FIRST_PROBE_MAX_MS = 15_000;
const REGULAR_PROBE_MIN_MS = 30 * 60_000;
const REGULAR_PROBE_MAX_MS = 60 * 60_000;
const CONFIRM_BACKOFF_STEPS_MS = [30_000, 120_000] as const;
const NETWORK_RETRY_MS = 2 * 60_000;
const STALE_AFTER_MS = 45 * 60_000;
const PREFLIGHT_MAX_AGE_MS = 15 * 60_000;

interface PersistedAccountHealthRecord {
  accountId: string;
  platform: string;
  lastVerifiedAt: number | null;
  lastAuthFailureAt: number | null;
  profile: AccountHealthProfile | null;
  sessionFingerprint: string | null;
}

interface AccountHealthRecord {
  accountId: string;
  platform: string;
  authState: AccountAuthState;
  probeState: AccountProbeState;
  authReason: AccountAuthReason;
  lastVerifiedAt: number | null;
  lastProbeAt: number | null;
  nextProbeAt: number | null;
  lastAuthFailureAt: number | null;
  profile: AccountHealthProfile | null;
  sessionFingerprint: string | null;
  suspectedExpiredAt: number | null;
  confirmFailureCount: number;
}

const trackedAccounts = new Map<string, PublishAccountIdentity>();
const records = new Map<string, AccountHealthRecord>();
const accountLocks = new Map<string, Promise<void>>();
let initialized = false;
let probeTimer: ReturnType<typeof setInterval> | null = null;

function randomInt(min: number, max: number): number {
  if (max <= min) {
    return min;
  }
  return min + Math.floor(Math.random() * (max - min));
}

function persistedHealthPath(): string {
  return join(app.getPath("userData"), "desktop-account-health.json");
}

function resolvePartition(accountId: string): string {
  return getSessionHandle(accountId)?.partition ?? getPersistedPartition(accountId) ?? `persist:acc-${accountId}`;
}

function nextInitialProbeAt(now = Date.now()): number {
  return now + randomInt(FIRST_PROBE_MIN_MS, FIRST_PROBE_MAX_MS);
}

function nextRegularProbeAt(now = Date.now()): number {
  return now + randomInt(REGULAR_PROBE_MIN_MS, REGULAR_PROBE_MAX_MS);
}

function normalizePersisted(
  record: PersistedAccountHealthRecord,
): AccountHealthRecord {
  return {
    accountId: record.accountId,
    platform: record.platform,
    authState: "unknown",
    probeState: "idle",
    authReason: null,
    lastVerifiedAt: record.lastVerifiedAt ?? null,
    lastProbeAt: null,
    nextProbeAt: nextInitialProbeAt(),
    lastAuthFailureAt: record.lastAuthFailureAt ?? null,
    profile: record.profile ?? null,
    sessionFingerprint: record.sessionFingerprint ?? null,
    suspectedExpiredAt: null,
    confirmFailureCount: 0,
  };
}

function loadPersistedRecords(): void {
  try {
    const raw = JSON.parse(readFileSync(persistedHealthPath(), "utf8")) as PersistedAccountHealthRecord[];
    for (const item of raw) {
      if (!item?.accountId || !item?.platform) {
        continue;
      }
      records.set(item.accountId, normalizePersisted(item));
    }
  } catch {
    records.clear();
  }
}

function persistRecords(): void {
  const payload: PersistedAccountHealthRecord[] = [...records.values()].map((record) => ({
    accountId: record.accountId,
    platform: record.platform,
    lastVerifiedAt: record.lastVerifiedAt,
    lastAuthFailureAt: record.lastAuthFailureAt,
    profile: record.profile,
    sessionFingerprint: record.sessionFingerprint,
  }));

  const target = persistedHealthPath();
  mkdirSync(dirname(target), { recursive: true });
  writeFileSync(target, JSON.stringify(payload, null, 2), "utf8");
}

function ensureInitialized(): void {
  if (initialized) {
    return;
  }

  initialized = true;
  loadPersistedRecords();
}

function ensureProbeTimer(): void {
  ensureInitialized();
  if (probeTimer) {
    return;
  }

  probeTimer = setInterval(() => {
    void runDueProbes();
  }, PROBE_TICK_MS);
}

function coerceDerivedAuthState(record: AccountHealthRecord, now = Date.now()): AccountAuthState {
  if (
    record.authState === "active"
    && record.lastVerifiedAt
    && now - record.lastVerifiedAt >= STALE_AFTER_MS
  ) {
    return "expiring_soon";
  }

  return record.authState;
}

function toPublicSnapshot(record: AccountHealthRecord): AccountHealthSnapshot {
  return {
    accountId: record.accountId,
    platform: record.platform,
    partition: resolvePartition(record.accountId),
    authState: coerceDerivedAuthState(record),
    probeState: record.probeState,
    authReason: record.authReason,
    lastVerifiedAt: record.lastVerifiedAt,
    lastProbeAt: record.lastProbeAt,
    nextProbeAt: record.nextProbeAt,
    lastAuthFailureAt: record.lastAuthFailureAt,
    profile: record.profile,
    sessionFingerprint: record.sessionFingerprint,
  };
}

function snapshotSignature(record: AccountHealthRecord): string {
  return JSON.stringify(toPublicSnapshot(record));
}

function commitRecord(record: AccountHealthRecord, previousSignature: string | null): AccountHealthSnapshot {
  records.set(record.accountId, record);
  persistRecords();

  const nextSignature = snapshotSignature(record);
  if (previousSignature !== nextSignature) {
    emitRuntimeInvalidated("account-health");
  }

  return toPublicSnapshot(record);
}

function ensureRecord(account: PublishAccountIdentity): AccountHealthRecord {
  ensureInitialized();

  const existing = records.get(account.id);
  if (existing) {
    existing.platform = account.platform;
    return existing;
  }

  const created: AccountHealthRecord = {
    accountId: account.id,
    platform: account.platform,
    authState: "unknown",
    probeState: "idle",
    authReason: null,
    lastVerifiedAt: null,
    lastProbeAt: null,
    nextProbeAt: nextInitialProbeAt(),
    lastAuthFailureAt: null,
    profile: null,
    sessionFingerprint: null,
    suspectedExpiredAt: null,
    confirmFailureCount: 0,
  };

  records.set(account.id, created);
  persistRecords();
  return created;
}

async function withAccountLock<T>(accountId: string, work: () => Promise<T>): Promise<T> {
  const previous = accountLocks.get(accountId) ?? Promise.resolve();
  let release!: () => void;
  const current = new Promise<void>((resolve) => {
    release = resolve;
  });

  accountLocks.set(accountId, current);
  await previous.catch(() => undefined);

  try {
    return await work();
  } finally {
    release();
    if (accountLocks.get(accountId) === current) {
      accountLocks.delete(accountId);
    }
  }
}

function confirmBackoffMs(failureCount: number): number {
  const index = Math.min(Math.max(failureCount - 1, 0), CONFIRM_BACKOFF_STEPS_MS.length - 1);
  return CONFIRM_BACKOFF_STEPS_MS[index] ?? CONFIRM_BACKOFF_STEPS_MS[CONFIRM_BACKOFF_STEPS_MS.length - 1];
}

function applyActiveResult(
  record: AccountHealthRecord,
  result: AuthProbeResult,
  now: number,
): AccountHealthSnapshot {
  const previousSignature = snapshotSignature(record);

  record.authState = "active";
  record.probeState = "idle";
  record.authReason = result.reason ?? "probe_success";
  record.lastVerifiedAt = now;
  record.lastProbeAt = now;
  record.nextProbeAt = nextRegularProbeAt(now);
  record.profile = result.profile ?? record.profile;
  record.sessionFingerprint = result.sessionFingerprint ?? record.sessionFingerprint;
  record.suspectedExpiredAt = null;
  record.confirmFailureCount = 0;

  return commitRecord(record, previousSignature);
}

function applyExpiredResult(
  record: AccountHealthRecord,
  result: AuthProbeResult,
  now: number,
): AccountHealthSnapshot {
  const previousSignature = snapshotSignature(record);

  record.authState = "expired";
  record.probeState = "idle";
  record.authReason = result.reason ?? "login_redirect";
  record.lastProbeAt = now;
  record.nextProbeAt = nextRegularProbeAt(now);
  record.lastAuthFailureAt = now;
  record.suspectedExpiredAt = null;
  record.confirmFailureCount = 0;

  return commitRecord(record, previousSignature);
}

function applyChallengeResult(
  record: AccountHealthRecord,
  result: AuthProbeResult,
  now: number,
): AccountHealthSnapshot {
  const previousSignature = snapshotSignature(record);

  record.authState = "challenge_required";
  record.probeState = "idle";
  record.authReason = result.reason ?? "captcha_gate";
  record.lastProbeAt = now;
  record.nextProbeAt = nextRegularProbeAt(now);
  record.lastAuthFailureAt = now;
  record.suspectedExpiredAt = null;
  record.confirmFailureCount = 0;

  return commitRecord(record, previousSignature);
}

function applyNetworkResult(
  record: AccountHealthRecord,
  result: AuthProbeResult,
  now: number,
  trigger: "scheduled" | "manual" | "preflight" | "confirm",
): AccountHealthSnapshot {
  const previousSignature = snapshotSignature(record);
  const hadSuspicion = Boolean(record.suspectedExpiredAt);

  record.probeState = "network_error";
  record.authReason = result.reason ?? "network_error";
  record.lastProbeAt = now;
  if (hadSuspicion && trigger === "confirm") {
    record.confirmFailureCount += 1;
    record.authState = record.authState === "unknown" ? "unknown" : "expiring_soon";
    record.nextProbeAt = now + confirmBackoffMs(record.confirmFailureCount);
  } else {
    record.nextProbeAt = now + NETWORK_RETRY_MS;
    if (record.authState === "active") {
      record.authState = "expiring_soon";
    }
  }

  return commitRecord(record, previousSignature);
}

async function performProbeLocked(
  account: PublishAccountIdentity,
  options: {
    trigger: "scheduled" | "manual" | "preflight" | "confirm";
    allowSilentRefresh: boolean;
  },
): Promise<AccountHealthSnapshot> {
  const record = ensureRecord(account);
  const adapter = getPlatformAdapter(account.platform);
  const previousSignature = snapshotSignature(record);

  record.probeState = "probing";
  commitRecord(record, previousSignature);

  const partition = resolvePartition(account.id);

  if (options.allowSilentRefresh) {
    const refreshed = await adapter.silentRefresh(account, partition).catch(() => false);
    if (!refreshed) {
      const currentSignature = snapshotSignature(record);
      record.authReason = "silent_refresh_failed";
      commitRecord(record, currentSignature);
    }
  }

  const result = await adapter.probe(account, partition).catch<AuthProbeResult>(() => ({
    verdict: "network_error",
    reason: "network_error",
    profile: null,
    sessionFingerprint: null,
  }));

  const now = Date.now();
  switch (result.verdict) {
    case "active":
      return applyActiveResult(record, result, now);
    case "expired":
      return applyExpiredResult(record, result, now);
    case "challenge_required":
      return applyChallengeResult(record, result, now);
    default:
      return applyNetworkResult(record, result, now, options.trigger);
  }
}

async function runDueProbes(): Promise<void> {
  const now = Date.now();
  const dueAccounts = [...trackedAccounts.values()].filter((account) => {
    const record = records.get(account.id);
    return Boolean(record?.nextProbeAt && record.nextProbeAt <= now);
  });

  for (const account of dueAccounts) {
    const record = records.get(account.id);
    if (!record) {
      continue;
    }

    const trigger = record.suspectedExpiredAt ? "confirm" : "scheduled";
    void withAccountLock(account.id, async () => {
      await performProbeLocked(account, {
        trigger,
        allowSilentRefresh: false,
      });
    });
  }
}

function parseVerifiedAt(value: string | null | undefined): number | null {
  if (!value) {
    return null;
  }

  const timestamp = Date.parse(value);
  return Number.isNaN(timestamp) ? null : timestamp;
}

function fallbackAuthState(
  health: DesktopAccountInfo["health"] | null | undefined,
): AccountAuthState {
  switch (health) {
    case "live":
      return "unknown";
    case "captcha":
      return "challenge_required";
    case "expired":
      return "expired";
    default:
      return "unknown";
  }
}

export function initAccountHealth(): void {
  ensureInitialized();
  ensureProbeTimer();
}

export function syncTrackedAccounts(accounts: PublishAccountIdentity[]): void {
  syncTrackedAccountsInternal(accounts, true);
}

function syncTrackedAccountsInternal(
  accounts: PublishAccountIdentity[],
  pruneMissing: boolean,
): void {
  initAccountHealth();
  let removed = false;

  if (pruneMissing) {
    const nextIds = new Set(accounts.map((account) => account.id));
    for (const [accountId] of trackedAccounts.entries()) {
      if (!nextIds.has(accountId)) {
        trackedAccounts.delete(accountId);
        records.delete(accountId);
        removed = true;
      }
    }
  }

  for (const account of accounts) {
    trackedAccounts.set(account.id, account);
    ensureRecord(account);
  }

  persistRecords();
  if (removed) {
    emitRuntimeInvalidated("account-health");
  }
}

export function forgetTrackedAccountHealth(
  accountId: string,
): void {
  trackedAccounts.delete(accountId);
  if (records.delete(accountId)) {
    persistRecords();
    emitRuntimeInvalidated("account-health");
  }
}

export function getAccountHealthSnapshot(accountId: string): AccountHealthSnapshot | null {
  ensureInitialized();
  const record = records.get(accountId);
  return record ? toPublicSnapshot(record) : null;
}

export function getProjectedAccountHealth(input: {
  accountId: string;
  platform: string;
  health?: DesktopAccountInfo["health"];
  verifiedAt?: string | null;
}) {
  const snapshot = getAccountHealthSnapshot(input.accountId);
  if (!snapshot) {
    return {
      health: input.health ?? "risk",
      authState: fallbackAuthState(input.health),
      probeState: "idle" as AccountProbeState,
      authReason: null as AccountAuthReason,
      lastVerifiedAt: parseVerifiedAt(input.verifiedAt),
      lastProbeAt: null,
      nextProbeAt: null,
      lastAuthFailureAt: null,
      profile: null,
      sessionFingerprint: null,
      partition: resolvePartition(input.accountId),
    };
  }

  const health =
    snapshot.authState === "active"
      ? ("live" as const)
      : snapshot.authState === "challenge_required"
        ? ("captcha" as const)
        : snapshot.authState === "expired" || snapshot.authState === "revoked"
          ? ("expired" as const)
          : ("risk" as const);

  return {
    ...snapshot,
    health,
  };
}

export async function probeTrackedAccount(
  account: PublishAccountIdentity,
  options: {
    trigger?: "scheduled" | "manual" | "preflight" | "confirm";
    allowSilentRefresh?: boolean;
  } = {},
): Promise<AccountHealthSnapshot> {
  syncTrackedAccountsInternal([account], false);
  return await withAccountLock(account.id, async () => {
    return await performProbeLocked(account, {
      trigger: options.trigger ?? "manual",
      allowSilentRefresh: Boolean(options.allowSilentRefresh),
    });
  });
}

export async function ensureAccountReady(
  account: PublishAccountIdentity,
): Promise<AccountHealthSnapshot> {
  syncTrackedAccountsInternal([account], false);
  const snapshot = getAccountHealthSnapshot(account.id);
  const isFresh =
    snapshot?.lastVerifiedAt
    ? Date.now() - snapshot.lastVerifiedAt < PREFLIGHT_MAX_AGE_MS
    : false;

  if (
    snapshot
    && snapshot.authState === "active"
    && snapshot.probeState !== "network_error"
    && isFresh
  ) {
    return snapshot;
  }

  if (
    snapshot
    && ["expired", "challenge_required", "revoked"].includes(snapshot.authState)
    && !(account.platform === "baijiahao" && snapshot.authState === "challenge_required")
  ) {
    return snapshot;
  }

  return await withAccountLock(account.id, async () => {
    const lockedSnapshot = getAccountHealthSnapshot(account.id);
    const lockedFresh =
      lockedSnapshot?.lastVerifiedAt
      ? Date.now() - lockedSnapshot.lastVerifiedAt < PREFLIGHT_MAX_AGE_MS
      : false;

    if (
      lockedSnapshot
      && lockedSnapshot.authState === "active"
      && lockedSnapshot.probeState !== "network_error"
      && lockedFresh
    ) {
      return lockedSnapshot;
    }

    return await performProbeLocked(account, {
      trigger: "preflight",
      allowSilentRefresh: true,
    });
  });
}

export async function reportAccountFailure(
  account: PublishAccountIdentity,
  input: PlatformFailureInput,
): Promise<AccountHealthSnapshot | null> {
  syncTrackedAccountsInternal([account], false);
  const adapter = getPlatformAdapter(account.platform);
  const classification = adapter.classifyFailure(input);

  if (classification === "ok") {
    return getAccountHealthSnapshot(account.id);
  }

  return await withAccountLock(account.id, async () => {
    const record = ensureRecord(account);
    const previousSignature = snapshotSignature(record);
    const now = Date.now();

    if (classification === "challenge" || classification === "risk_control") {
      record.authState = "challenge_required";
      record.probeState = "idle";
      record.authReason = classification === "risk_control" ? "risk_control" : "captcha_gate";
      record.lastAuthFailureAt = now;
      record.lastProbeAt = now;
      record.nextProbeAt = nextRegularProbeAt(now);
      record.suspectedExpiredAt = null;
      record.confirmFailureCount = 0;
      return commitRecord(record, previousSignature);
    }

    if (classification === "network") {
      record.probeState = "network_error";
      record.authReason = "network_error";
      record.lastProbeAt = now;
      record.nextProbeAt = now + NETWORK_RETRY_MS;
      return commitRecord(record, previousSignature);
    }

    record.lastAuthFailureAt = now;
    record.suspectedExpiredAt = record.suspectedExpiredAt ?? now;
    if (record.authState === "active") {
      record.authState = "expiring_soon";
    }
    record.nextProbeAt = now;
    commitRecord(record, previousSignature);

    return await performProbeLocked(account, {
      trigger: "confirm",
      allowSilentRefresh: false,
    });
  });
}