export function validateChatHistory()

in src/methods/chat-session-helpers.ts [47:104]
53 lines of code
13 McCabe index (conditional complexity)

export function validateChatHistory(history: Content[]): void {
  let prevContent = false;
  for (const currContent of history) {
    const { role, parts } = currContent as { role: Role; parts: Part[] };
    if (!prevContent && role !== "user") {
      throw new GoogleGenerativeAIError(
        `First content should be with role 'user', got ${role}`,
      );
    }
    if (!POSSIBLE_ROLES.includes(role)) {
      throw new GoogleGenerativeAIError(
        `Each item should include role field. Got ${role} but valid roles are: ${JSON.stringify(
          POSSIBLE_ROLES,
        )}`,
      );
    }

    if (!Array.isArray(parts)) {
      throw new GoogleGenerativeAIError(
        "Content should have 'parts' property with an array of Parts",
      );
    }

    if (parts.length === 0) {
      throw new GoogleGenerativeAIError(
        "Each Content should have at least one part",
      );
    }

    const countFields: Record<keyof Part, number> = {
      text: 0,
      inlineData: 0,
      functionCall: 0,
      functionResponse: 0,
      fileData: 0,
      executableCode: 0,
      codeExecutionResult: 0,
    };

    for (const part of parts) {
      for (const key of VALID_PART_FIELDS) {
        if (key in part) {
          countFields[key] += 1;
        }
      }
    }
    const validParts = VALID_PARTS_PER_ROLE[role];
    for (const key of VALID_PART_FIELDS) {
      if (!validParts.includes(key) && countFields[key] > 0) {
        throw new GoogleGenerativeAIError(
          `Content with role '${role}' can't contain '${key}' part`,
        );
      }
    }

    prevContent = true;
  }
}