// Persisted LLM settings — base URL, context budget, response cap.
// Reactive across tabs (storage event) and within the same tab (custom event).

import { useEffect, useSyncExternalStore } from "react"

export type LLMSettings = {
  baseURL: string
  contextTokens: number
  responseBudget: number
}

export const DEFAULT_SETTINGS: LLMSettings = {
  baseURL: "http://localhost:1234/v1",
  contextTokens: 9000,
  responseBudget: 512,
}

const STORAGE_KEY = "crema.llm.settings"
const CHANGE_EVENT = "comfy:llm-settings-change"

function readFromStorage(): LLMSettings {
  if (typeof window === "undefined") return DEFAULT_SETTINGS
  try {
    const raw = localStorage.getItem(STORAGE_KEY)
    if (!raw) return DEFAULT_SETTINGS
    const parsed = JSON.parse(raw) as Partial<LLMSettings>
    return {
      baseURL: typeof parsed.baseURL === "string" ? parsed.baseURL : DEFAULT_SETTINGS.baseURL,
      contextTokens:
        Number.isFinite(parsed.contextTokens) && (parsed.contextTokens as number) > 0
          ? (parsed.contextTokens as number)
          : DEFAULT_SETTINGS.contextTokens,
      responseBudget:
        Number.isFinite(parsed.responseBudget) && (parsed.responseBudget as number) > 0
          ? (parsed.responseBudget as number)
          : DEFAULT_SETTINGS.responseBudget,
    }
  } catch {
    return DEFAULT_SETTINGS
  }
}

export function loadLLMSettings(): LLMSettings {
  return readFromStorage()
}

export function saveLLMSettings(next: LLMSettings) {
  if (typeof window === "undefined") return
  localStorage.setItem(STORAGE_KEY, JSON.stringify(next))
  window.dispatchEvent(new CustomEvent(CHANGE_EVENT))
}

export function resetLLMSettings() {
  saveLLMSettings(DEFAULT_SETTINGS)
}

let cached: LLMSettings | null = null

function subscribe(cb: () => void): () => void {
  const onChange = () => {
    cached = null
    cb()
  }
  window.addEventListener(CHANGE_EVENT, onChange)
  window.addEventListener("storage", (e) => {
    if (e.key === STORAGE_KEY) onChange()
  })
  return () => {
    window.removeEventListener(CHANGE_EVENT, onChange)
  }
}

function getSnapshot(): LLMSettings {
  if (!cached) cached = readFromStorage()
  return cached
}

function getServerSnapshot(): LLMSettings {
  return DEFAULT_SETTINGS
}

export function useLLMSettings(): LLMSettings {
  // useSyncExternalStore avoids hydration flicker and stays reactive.
  const value = useSyncExternalStore(subscribe, getSnapshot, getServerSnapshot)
  // Re-read after mount to pick up localStorage on first client render.
  useEffect(() => {
    cached = null
  }, [])
  return value
}