import type { LoaderContext } from '@rspack/core';
import { parse } from 'csv-parse/sync';
import { parseSchema, createValidator, parseValue } from '../index.js';

export interface CsvLoaderOptions {
  delimiter?: string;
  quote?: string;
  escape?: string;
}

interface PropertyConfig {
  name: string;
  schema: any;
  validator: (value: unknown) => boolean;
  parser: (valueString: string) => unknown;
}

export default function csvLoader(
  this: LoaderContext<CsvLoaderOptions>,
  content: string
): string {
  const options = this.getOptions() || {};
  const delimiter = options.delimiter ?? ',';
  const quote = options.quote ?? '"';
  const escape = options.escape ?? '\\';

  const records = parse(content, {
    delimiter,
    quote,
    escape,
    relax_column_count: true,
  });

  if (records.length < 2) {
    throw new Error('CSV must have at least 2 rows: headers and schemas');
  }

  const headers = records[0];
  const schemas = records[1];

  if (headers.length !== schemas.length) {
    throw new Error(
      `Header count (${headers.length}) does not match schema count (${schemas.length})`
    );
  }

  const propertyConfigs: PropertyConfig[] = headers.map((header: string, index: number) => {
    const schemaString = schemas[index];
    const schema = parseSchema(schemaString);
    return {
      name: header,
      schema,
      validator: createValidator(schema),
      parser: (valueString: string) => parseValue(schema, valueString),
    };
  });

  const dataRows = records.slice(2);
  const objects = dataRows.map((row: string[], rowIndex: number) => {
    const obj: Record<string, unknown> = {};
    propertyConfigs.forEach((config, colIndex) => {
      const rawValue = row[colIndex] ?? '';
      try {
        const parsed = config.parser(rawValue);
        if (!config.validator(parsed)) {
          throw new Error(
            `Validation failed for property "${config.name}" at row ${rowIndex + 3}: ${rawValue}`
          );
        }
        obj[config.name] = parsed;
      } catch (error) {
        if (error instanceof Error) {
          throw new Error(
            `Failed to parse property "${config.name}" at row ${rowIndex + 3}, column ${colIndex + 1}: ${error.message}`
          );
        }
        throw error;
      }
    });
    return obj;
  });

  const json = JSON.stringify(objects, null, 2);
  return `export default ${json};`;
}