/**
 * Cliente HTTP mínimo para o gateway MCP (JSON-RPC 2.0 sobre HTTP).
 *
 * Suporta resposta em JSON puro ou SSE (text/event-stream). Partilhado entre
 * os scripts de Observabilidade (patterns + worklog import).
 */

export interface MCPToolCallResult {
  content?: Array<{ type: string; text: string }>
  isError?: boolean
}

export async function callMcpTool(
  tool: string,
  args: Record<string, unknown>,
): Promise<MCPToolCallResult> {
  const url = process.env.MCP_GATEWAY_URL ?? 'https://gateway.descomplicar.pt/v1/desk-crm/mcp'
  const token = process.env.MCP_GATEWAY_TOKEN
  if (!token) throw new Error('MCP_GATEWAY_TOKEN não definido')
  const body = {
    jsonrpc: '2.0',
    id: Date.now(),
    method: 'tools/call',
    params: { name: tool, arguments: args },
  }
  const res = await fetch(url, {
    method: 'POST',
    headers: {
      Authorization: `Bearer ${token}`,
      'Content-Type': 'application/json',
      Accept: 'application/json, text/event-stream',
    },
    body: JSON.stringify(body),
  })
  if (!res.ok) {
    const txt = await res.text().catch(() => '')
    throw new Error(`MCP gateway ${res.status}: ${txt.slice(0, 300)}`)
  }
  const raw = await res.text()
  let payload: string | null = null
  for (const line of raw.split(/\r?\n/)) {
    const trimmed = line.trim()
    if (!trimmed) continue
    if (trimmed.startsWith('data: ')) {
      payload = trimmed.slice(6)
      break
    }
    if (trimmed.startsWith('{')) {
      payload = trimmed
      break
    }
  }
  if (!payload) throw new Error(`MCP resposta sem payload JSON: ${raw.slice(0, 200)}`)
  const parsed = JSON.parse(payload) as { error?: unknown; result?: MCPToolCallResult }
  if (parsed.error) throw new Error(`MCP error: ${JSON.stringify(parsed.error)}`)
  const result = parsed.result as MCPToolCallResult | undefined
  if (result?.isError) {
    const txt = result.content?.map((c) => c.text).join('\n') ?? ''
    throw new Error(`MCP tool ${tool} devolveu isError: ${txt.slice(0, 300)}`)
  }
  return result ?? {}
}

/** Extrai o primeiro bloco de texto JSON-encoded do resultado MCP. */
export function extractMcpJsonPayload<T = unknown>(r: MCPToolCallResult): T {
  const text = r.content?.find((c) => c.type === 'text')?.text
  if (!text) throw new Error('MCP result sem content text')
  return JSON.parse(text) as T
}