import * as Sampler from 'openapi-sampler';
import { OpenAPIExample, OpenAPISchema } from '../types';
import { Example } from '../types/example';
import { MergedOpenAPISchema, OpenAPIParser } from '../services';

const MAX_ITEM_DEPTH = 1;

interface CsvExampleProps {
  parser: OpenAPIParser;
  schema: OpenAPISchema;
  sample: OpenAPIExample;
  samplerOptions: object;
}

const getCsvRows = (sample: OpenAPIExample): string => {
  const headers = Object.keys(sample?.[0] ?? sample).join(',');
  // Ensure the schema has deterministic headers
  const hasValidHeaders =
    !Array.isArray(sample) ||
    sample.every(row => Object.keys(row).every(key => headers.includes(key)));
  if (!hasValidHeaders) return '';

  let values;

  if (Array.isArray(sample)) {
    values = sample.map(row => Object.values(row)).join('\n');
  } else {
    values = Object.values(sample).join(',');
  }
  return headers + '\n' + values;
};

const cleanUpExamples = (examples: Example[]): Example[] =>
  examples.filter(example => example.exampleValue !== '');

export const generateCsvExample = ({
  parser,
  schema,
  sample,
  samplerOptions,
}: CsvExampleProps): Example[] => {
  let examples: Example[] = [];
  let depthCount = 0;
  let exampleCount = 1;
  const isValidSample = (Array.isArray(sample) ? sample : [sample]).every(sampleItem =>
    Object.values(sampleItem).every(
      value => typeof value !== 'object' && typeof value !== 'undefined',
    ),
  );

  const processSamplesWithSchema = subSchema => {
    if (subSchema) {
      const subItems = subSchema.items as OpenAPISchema;

      if (subSchema.type === 'array' && subItems && depthCount < MAX_ITEM_DEPTH) {
        depthCount++;
        processSamplesWithSchema(subItems);
      }

      const metadata = {
        exampleDescription: subSchema.description || schema.description || '',
        exampleSummary: subSchema.title || schema.title || 'Example CSV',
      };

      if (subSchema?.allOf) {
        const resolved: OpenAPISchema = {
          ...schema,
          items: parser.deref(subSchema.allOf as MergedOpenAPISchema).resolved,
        };
        const sampleData = Sampler.sample(
          resolved as any,
          samplerOptions,
          parser.spec,
        ) as OpenAPIExample;

        const csvRows = getCsvRows(sampleData);
        examples.push({
          exampleId: `Example ${exampleCount++}`,
          exampleValue: csvRows,
          ...metadata,
        });
      } else if (subSchema.oneOf) {
        const oneOfExamples = subSchema.oneOf.map(oneOfSchema => {
          const { resolved } = parser.deref(oneOfSchema as MergedOpenAPISchema);
          const sampleData = Sampler.sample(
            resolved as any,
            samplerOptions,
            parser.spec,
          ) as OpenAPIExample;
          const csvRows = getCsvRows(sampleData);
          const currentMetadata = {
            exampleDescription: oneOfSchema.description || metadata.exampleDescription,
            exampleSummary: oneOfSchema.title || metadata.exampleSummary,
          };

          return {
            exampleId: `Example ${exampleCount++}`,
            exampleValue: csvRows,
            ...currentMetadata,
          };
        });
        examples = [...examples, ...oneOfExamples];
      } else if (subSchema.$ref) {
        const csvRows = getCsvRows(sample);
        examples.push({
          exampleId: `Example ${exampleCount++}`,
          exampleValue: csvRows,
          ...metadata,
        });
      }
    }
  };

  if (isValidSample) {
    processSamplesWithSchema(schema);
  }

  return cleanUpExamples(examples);
};