import {
  Message,
  Method,
  ObjectField,
  ScalarField,
  Schema,
  Service,
} from "./protobuf-dsl-types";

const REPEATED = "repeated";

export async function print(schema: Schema): Promise<string> {
  const statements = [];
  const head = `syntax = "proto3";\n
                 package ${schema.name};`;

  statements.push(head);


  const service = printService(schema.service);

  statements.push(service);

  const messages = printMessages(schema.messages);

  statements.push(messages);

  return statements.join("\n");
}

export function printDocumentation(documentation: string): string {
  return `/// ${documentation}`;
}

export function printService(service: Service): string {
  const methodTexts = service.methods
    .map((method) => printMethod(method))
    .join("\n");

  return `service ${service.name} {\n ${methodTexts} \n }`;
}

function printMethod(method: Method): string {
  return `rpc ${method.name} (${method.inputObjectName}) returns (${method.outputObjectName}) {}`;
}

export function printMessages(messages: Message[]): string {
  const methodTexts = messages
    .map((message) => printMessage(message))
    .join("\n");

  return methodTexts;
}

function printMessage(message: Message): string {
  const fieldTexts = message.fields
    .map((field) => printField(field))
    .join("\n");

  return `message ${message.name} {\n${fieldTexts}\n};`;
}

function printField(field: ObjectField | ScalarField): string {
  return field.kind === "scalar"
    ? printScalarField(field)
    : printObjectField(field);
}

function printScalarField(field: ScalarField): string {
  return field.isList
    ? `${REPEATED} ${field.type} ${field.name} = ${field.locNumber};`
    : `${field.type} ${field.name} = ${field.locNumber};`;
}

function printObjectField(field: ObjectField): string {
  return field.isList
    ? `${REPEATED} ${field.type} ${field.name} = ${field.locNumber};`
    : `${field.type} ${field.name} = ${field.locNumber};`;
}