export interface StreamEvent {
  type: string;
  subtype?: string;
  message?: {
    content?: Array<{
      type: string;
      name?: string;
      input?: Record<string, unknown>;
      text?: string;
    }>;
  };
  tool_use_result?: {
    success?: boolean;
    commandName?: string;
    content?: string;
  };
  result?: string;
  is_error?: boolean;
  duration_ms?: number;
  total_cost_usd?: number;
}

export function formatEventForLog(event: StreamEvent): string | null {
  if (event.type === "system" && event.subtype === "init") {
    return `=== Session started ===\n`;
  }

  if (event.type === "assistant" && event.message?.content) {
    const parts: string[] = [];
    for (const block of event.message.content) {
      if (block.type === "text" && block.text) {
        parts.push(`[assistant]\n${block.text}\n`);
      } else if (block.type === "tool_use" && block.name) {
        const inputStr = block.input
          ? JSON.stringify(block.input, null, 2)
          : "{}";
        parts.push(`[tool_use: ${block.name}]\n${inputStr}\n`);
      }
    }
    return parts.length > 0 ? parts.join("\n") : null;
  }

  if (event.type === "user" && event.message?.content) {
    const parts: string[] = [];
    for (const block of event.message.content as Array<{
      type: string;
      content?: string;
    }>) {
      if (block.type === "tool_result" && block.content) {
        parts.push(`[tool_result]\n${block.content}\n`);
      }
    }
    return parts.length > 0 ? parts.join("\n") : null;
  }

  if (event.type === "result") {
    const lines = [`=== Result ===`];
    if (event.is_error) lines.push(`ERROR`);
    if (event.result) lines.push(event.result);
    if (event.duration_ms)
      lines.push(`Duration: ${(event.duration_ms / 1000).toFixed(1)}s`);
    if (event.total_cost_usd)
      lines.push(`Cost: $${event.total_cost_usd.toFixed(4)}`);
    return lines.join("\n") + "\n";
  }

  return null;
}

export function parseStreamEvents(output: string): StreamEvent[] {
  return output
    .split("\n")
    .filter((line) => line.trim())
    .map((line) => {
      try {
        return JSON.parse(line) as StreamEvent;
      } catch {
        return null;
      }
    })
    .filter((e): e is StreamEvent => e !== null);
}