import { eq, gt, lt } from "drizzle-orm";
import { db } from "../db/client.js";
import { dnsProviders, integrations, maintenanceWindows, servers } from "../db/schema.js";

export type ActiveWindow = typeof maintenanceWindows.$inferSelect;

/** Windows whose end is still in the future. ISO strings compare correctly as text, so this is a plain string comparison. */
export async function listActiveWindows(now: Date = new Date()): Promise<ActiveWindow[]> {
  return db.select().from(maintenanceWindows).where(gt(maintenanceWindows.endsAt, now.toISOString()));
}

/**
 * The identity a health condition or alert belongs to, as "server:3" /
 * "integration:1" / "dns_provider:2", so it can be matched against active windows.
 * Derived from the condition key (which already encodes it) rather than stored,
 * so conditions persisted by an earlier version still map correctly.
 */
export function subjectOfConditionKey(key: string): string | null {
  let m = /^(?:offline|disk):server:(\d+)(?::|$)/.exec(key);
  if (m) return `server:${m[1]}`;
  m = /^disk:proxmox:(\d+):/.exec(key);
  if (m) return `integration:${m[1]}`;
  m = /^(?:synology-volume|synology-disk|disk:synology):(\d+):/.exec(key);
  if (m) return `integration:${m[1]}`;
  m = /^automation:(?:semaphore|gitea):(\d+):/.exec(key);
  if (m) return `integration:${m[1]}`;
  return null;
}

export async function activeSubjects(now: Date = new Date()): Promise<Set<string>> {
  return new Set((await listActiveWindows(now)).map((w) => `${w.targetType}:${w.targetId}`));
}

export async function isInMaintenance(targetType: ActiveWindow["targetType"], targetId: number, now: Date = new Date()): Promise<boolean> {
  return (await activeSubjects(now)).has(`${targetType}:${targetId}`);
}

/**
 * Integration-failure alerts are tracked per service TYPE ("proxmox",
 * "cloudflare", ...), not per configured instance, so a window on any
 * integration or DNS provider of that type silences that type's failure alerts.
 * (With two integrations of one type, a real failure on the un-windowed one is
 * silenced too while the window is open — a known consequence of that
 * granularity, stated on the Maintenance page.)
 */
export async function isSourceInMaintenance(source: string, now: Date = new Date()): Promise<boolean> {
  const windows = await listActiveWindows(now);
  if (windows.length === 0) return false;
  for (const w of windows) {
    if (w.targetType === "integration") {
      const [row] = await db.select({ type: integrations.type }).from(integrations).where(eq(integrations.id, w.targetId)).limit(1);
      if (row?.type === source) return true;
    } else if (w.targetType === "dns_provider") {
      const [row] = await db.select({ type: dnsProviders.providerType }).from(dnsProviders).where(eq(dnsProviders.id, w.targetId)).limit(1);
      if (row?.type === source) return true;
    }
  }
  return false;
}

export interface StartWindowResult {
  window: ActiveWindow;
  target: { name: string; kind: string };
  /** True if this extended an already-active window rather than starting a new one. */
  extended: boolean;
}

/**
 * Starts a maintenance window for a target, or — if one is already active for it — extends it instead of
 * stacking a second one, pruning long-expired rows along the way. Returns null if the target doesn't exist.
 * Shared by the manual "Start maintenance" form and the Uptime Kuma import, so both silence alerts identically;
 * callers still record their own audit entry, since only they know the acting user.
 */
export async function startOrExtendWindow(
  targetType: ActiveWindow["targetType"],
  targetId: number,
  minutes: number,
  reason: string | null,
  createdBy: string | null,
  now: Date = new Date(),
): Promise<StartWindowResult | null> {
  const target = await describeTarget(targetType, targetId);
  if (!target) return null;

  const endsAt = new Date(now.getTime() + minutes * 60_000).toISOString();
  const existing = (await listActiveWindows(now)).find((w) => w.targetType === targetType && w.targetId === targetId);
  let window: ActiveWindow;
  if (existing) {
    [window] = await db.update(maintenanceWindows).set({ endsAt, reason, createdBy }).where(eq(maintenanceWindows.id, existing.id)).returning();
  } else {
    // Long-expired rows are just clutter; clear them out whenever a new one is added.
    await db.delete(maintenanceWindows).where(lt(maintenanceWindows.endsAt, new Date(now.getTime() - 24 * 3600_000).toISOString()));
    [window] = await db.insert(maintenanceWindows).values({ targetType, targetId, reason, startedAt: now.toISOString(), endsAt, createdBy }).returning();
  }
  return { window, target, extended: !!existing };
}

/** Display name for a window's target, or null if the target no longer exists. */
export async function describeTarget(targetType: ActiveWindow["targetType"], targetId: number): Promise<{ name: string; kind: string } | null> {
  if (targetType === "server") {
    const [r] = await db.select({ name: servers.name }).from(servers).where(eq(servers.id, targetId)).limit(1);
    return r ? { name: r.name, kind: "Server" } : null;
  }
  if (targetType === "integration") {
    const [r] = await db.select({ name: integrations.name, type: integrations.type }).from(integrations).where(eq(integrations.id, targetId)).limit(1);
    return r ? { name: r.name, kind: `Integration (${r.type})` } : null;
  }
  const [r] = await db.select({ name: dnsProviders.name, type: dnsProviders.providerType }).from(dnsProviders).where(eq(dnsProviders.id, targetId)).limit(1);
  return r ? { name: r.name, kind: `DNS provider (${r.type})` } : null;
}