// Shared state surface that any admin page can publish to so the assistant
// can read live data without scraping the DOM.
//
// Pages call `useRegisterAdminContext("tenants", { tenants: [...] })` while
// mounted; the assistant calls `getAdminContextSnapshot()` each turn to
// inject a structured snapshot into the system prompt.

import { useEffect } from "react"

type Surface = Record<string, unknown>

export type AdminContextSnapshot = {
  route: string
  surfaces: Record<string, Surface>
}

const surfaces = new Map<string, Surface>()

export function publishAdminSurface(name: string, data: Surface): void {
  surfaces.set(name, data)
  if (typeof window !== "undefined") {
    ;(window as unknown as { __adminContext?: unknown }).__adminContext = getAdminContextSnapshot()
  }
}

export function clearAdminSurface(name: string): void {
  surfaces.delete(name)
  if (typeof window !== "undefined") {
    ;(window as unknown as { __adminContext?: unknown }).__adminContext = getAdminContextSnapshot()
  }
}

export function getAdminContextSnapshot(): AdminContextSnapshot {
  const route = typeof window !== "undefined" ? window.location.pathname : ""
  return {
    route,
    surfaces: Object.fromEntries(surfaces.entries()),
  }
}

/**
 * Render a snapshot as a markdown block for the LLM system prompt.
 * Keeps it compact: route, then one section per surface with JSON.
 */
export function formatAdminContextForPrompt(snapshot = getAdminContextSnapshot()): string {
  const sections: string[] = [`Admin context (read-only — for answering factual questions):`]
  sections.push(`Route: ${snapshot.route || "?"}`)
  const names = Object.keys(snapshot.surfaces)
  if (names.length === 0) {
    sections.push(`Surfaces: (none registered)`)
  } else {
    for (const name of names) {
      const json = safeJson(snapshot.surfaces[name])
      sections.push(`Surface "${name}":\n${json}`)
    }
  }
  return sections.join("\n\n")
}

function safeJson(value: unknown): string {
  try {
    const text = JSON.stringify(value, null, 2)
    if (text.length > 4000) return text.slice(0, 4000) + "\n…(truncated)"
    return text
  } catch {
    return "(unserializable)"
  }
}

/** Hook: publish a surface while the component is mounted. */
export function useRegisterAdminContext(name: string, data: Surface): void {
  useEffect(() => {
    publishAdminSurface(name, data)
    return () => clearAdminSurface(name)
  }, [name, data])
}