import type { AiAgentMessage } from './aiAgentConversation'

interface BrowserNodePreview {
  nodeId: string
  text: string
}

export interface BrowserObservation {
  documentId?: string
  url: string
  totalCharacters?: number
  totalNodes?: number
  nodes: BrowserNodePreview[]
  status: 'pending' | 'done' | 'error'
}

function parseObject(value?: string): Record<string, unknown> | null {
  if (!value) return null
  try {
    const parsed: unknown = JSON.parse(value)
    return typeof parsed === 'object' && parsed !== null && !Array.isArray(parsed)
      ? parsed as Record<string, unknown>
      : null
  } catch {
    return null
  }
}

function stringField(object: Record<string, unknown> | null, ...keys: string[]): string | undefined {
  for (const key of keys) {
    const value = object?.[key]
    if (typeof value === 'string' && value.trim()) return value.trim()
  }
  return undefined
}

function numberField(object: Record<string, unknown> | null, ...keys: string[]): number | undefined {
  for (const key of keys) {
    const value = object?.[key]
    if (typeof value === 'number' && Number.isFinite(value)) return value
  }
  return undefined
}

function browserAction(action: AiAgentMessage['actions'][number]): boolean {
  if (action.tool === 'read_web_page' || action.tool === 'read_web_page_nodes') return true
  const input = parseObject(action.input)
  if (action.tool !== 'magic_brush') return false
  const steps = input?.steps
  return Array.isArray(steps) && steps.some((step) => (
    typeof step === 'object'
    && step !== null
    && ['read_web_page', 'read_web_page_nodes'].includes(String((step as Record<string, unknown>).tool))
  ))
}

function previewNodes(output: Record<string, unknown> | null): BrowserNodePreview[] {
  const raw = output?.node_previews ?? output?.nodes
  if (!Array.isArray(raw)) return []
  return raw.flatMap((item) => {
    if (typeof item !== 'object' || item === null) return []
    const node = item as Record<string, unknown>
    const nodeId = stringField(node, 'node_id', 'nodeId')
    const text = stringField(node, 'text')
    return nodeId && text ? [{ nodeId, text }] : []
  })
}

export function latestBrowserObservation(messages: AiAgentMessage[]): BrowserObservation | null {
  const actions = messages.flatMap((message) => message.actions).filter(browserAction)
  const action = actions.at(-1)
  if (!action) return null

  const input = parseObject(action.input)
  const output = parseObject(action.output)
  const url = stringField(output, 'url') ?? stringField(input, 'url')
  if (!url) return null

  return {
    documentId: stringField(output, 'document_id', 'documentId'),
    url,
    totalCharacters: numberField(output, 'total_characters', 'totalCharacters'),
    totalNodes: numberField(output, 'total_nodes', 'totalNodes'),
    nodes: previewNodes(output),
    status: action.status,
  }
}