import { useState, useCallback, useEffect } from 'react'
import type { Settings } from '../types/index'

const KEY = 'careless-v2-settings'

export const PROVIDER_DEFAULTS: Record<string, { model: string; maxTokens: number }> = {
  anthropic: { model: 'claude-opus-4-7', maxTokens: 8096 },
  openai: { model: 'gpt-5.5-2026-04-23', maxTokens: 8096 },
  google: { model: 'gemini-2.5-flash', maxTokens: 8096 },
  bedrock: { model: 'global.anthropic.claude-opus-4-7', maxTokens: 60000 },
  webllm: { model: 'Qwen2.5-0.5B-Instruct-q4f16_1-MLC', maxTokens: 4096 },
}

const DEFAULTS: Settings = {
  provider: 'anthropic',
  model: PROVIDER_DEFAULTS.anthropic.model,
  maxTokens: PROVIDER_DEFAULTS.anthropic.maxTokens,
  apiKey: '',
  fontSize: 18,
  debounceMs: 0,
  theme: 'dark',
  enableVision: true,
  enableMesh: true,
  enableMemory: true,
  enableTools: true,
  bedrockRegion: 'us-west-2',
}

export function useSettings() {
  const [settings, setSettings] = useState<Settings>(() => {
    try {
      const raw = localStorage.getItem(KEY)
      return raw ? { ...DEFAULTS, ...JSON.parse(raw) } : DEFAULTS
    } catch { return DEFAULTS }
  })

  const updateSettings = useCallback((patch: Partial<Settings>) => {
    setSettings(prev => {
      let next = { ...prev, ...patch }

      // Auto-flip model + maxTokens when provider changes
      if (patch.provider && patch.provider !== prev.provider) {
        const def = PROVIDER_DEFAULTS[patch.provider]
        if (def) {
          const prevDef = PROVIDER_DEFAULTS[prev.provider]
          // If user is on a provider-default model, swap to new provider's default.
          if (!prev.model || prev.model === prevDef?.model) {
            next.model = def.model
          }
          // Bedrock: enforce 60k floor. Others: swap default if user hadn't customized.
          if (patch.provider === 'bedrock') {
            next.maxTokens = Math.max(next.maxTokens ?? 0, def.maxTokens)
          } else if (!next.maxTokens || next.maxTokens === prevDef?.maxTokens) {
            next.maxTokens = def.maxTokens
          }
        }
      }

      try { localStorage.setItem(KEY, JSON.stringify(next)) } catch {}
      return next
    })
  }, [])

  useEffect(() => {
    const onStorage = (e: StorageEvent) => {
      if (e.key === KEY && e.newValue) {
        try { setSettings({ ...DEFAULTS, ...JSON.parse(e.newValue) }) } catch {}
      }
    }
    window.addEventListener('storage', onStorage)
    return () => window.removeEventListener('storage', onStorage)
  }, [])

  return { settings, updateSettings }
}