import { RacesApiClient } from '../../api/races/RacesApiClient';
import { RaceResultsDetailViewModel } from '../../view-models/RaceResultsDetailViewModel';
import { RaceWithSOFViewModel } from '../../view-models/RaceWithSOFViewModel';
import { ImportRaceResultsSummaryViewModel } from '../../view-models/ImportRaceResultsSummaryViewModel';
import type { ImportRaceResultsDTO } from '../../types/generated/ImportRaceResultsDTO';
import { v4 as uuidv4 } from 'uuid';

// Define types
type ImportRaceResultsInputDto = ImportRaceResultsDTO;
type ImportRaceResultsSummaryDto = {
  success: boolean;
  raceId: string;
  driversProcessed: number;
  resultsRecorded: number;
  errors?: string[];
};

export interface ImportResultRowDTO {
  id: string;
  raceId: string;
  driverId: string;
  position: number;
  fastestLap: number;
  incidents: number;
  startPosition: number;
}

export interface CSVRow {
  driverId: string;
  position: number;
  fastestLap: number;
  incidents: number;
  startPosition: number;
}

/**
 * Race Results Service
 *
 * Orchestrates race results operations including viewing, importing, and SOF calculations.
 * All dependencies are injected via constructor.
 */
export class RaceResultsService {
  constructor(
    private readonly apiClient: RacesApiClient
  ) {}

  /**
   * Get race results detail with view model transformation
   */
  async getResultsDetail(raceId: string, currentUserId?: string): Promise<RaceResultsDetailViewModel> {
    const dto = await this.apiClient.getResultsDetail(raceId);
    return new RaceResultsDetailViewModel(dto, currentUserId || '');
  }

  /**
    * Get race with strength of field calculation
    */
   async getWithSOF(raceId: string): Promise<RaceWithSOFViewModel> {
     const dto = await this.apiClient.getWithSOF(raceId);
     return new RaceWithSOFViewModel(dto);
   }

  /**
     * Import race results and get summary
     */
    async importResults(raceId: string, input: ImportRaceResultsInputDto): Promise<ImportRaceResultsSummaryViewModel> {
      const dto = await this.apiClient.importResults(raceId, input);
      return new ImportRaceResultsSummaryViewModel(dto);
    }

  /**
   * Parse CSV content and validate results
   * @throws Error with descriptive message if validation fails
   */
  parseCSV(content: string): CSVRow[] {
    const lines = content.trim().split('\n');

    if (lines.length < 2) {
      throw new Error('CSV file is empty or invalid');
    }

    const headerLine = lines[0]!;
    const header = headerLine.toLowerCase().split(',').map((h) => h.trim());
    const requiredFields = ['driverid', 'position', 'fastestlap', 'incidents', 'startposition'];

    for (const field of requiredFields) {
      if (!header.includes(field)) {
        throw new Error(`Missing required field: ${field}`);
      }
    }

    const rows: CSVRow[] = [];
    for (let i = 1; i < lines.length; i++) {
      const line = lines[i];
      if (!line) {
        continue;
      }
      const values = line.split(',').map((v) => v.trim());

      if (values.length !== header.length) {
        throw new Error(
          `Invalid row ${i}: expected ${header.length} columns, got ${values.length}`,
        );
      }

      const row: Record<string, string> = {};
      header.forEach((field, index) => {
        row[field] = values[index] ?? '';
      });

      const driverId = row['driverid'] ?? '';
      const position = parseInt(row['position'] ?? '', 10);
      const fastestLap = parseFloat(row['fastestlap'] ?? '');
      const incidents = parseInt(row['incidents'] ?? '', 10);
      const startPosition = parseInt(row['startposition'] ?? '', 10);

      if (!driverId || driverId.length === 0) {
        throw new Error(`Row ${i}: driverId is required`);
      }

      if (Number.isNaN(position) || position < 1) {
        throw new Error(`Row ${i}: position must be a positive integer`);
      }

      if (Number.isNaN(fastestLap) || fastestLap < 0) {
        throw new Error(`Row ${i}: fastestLap must be a non-negative number`);
      }

      if (Number.isNaN(incidents) || incidents < 0) {
        throw new Error(`Row ${i}: incidents must be a non-negative integer`);
      }

      if (Number.isNaN(startPosition) || startPosition < 1) {
        throw new Error(`Row ${i}: startPosition must be a positive integer`);
      }

      rows.push({ driverId, position, fastestLap, incidents, startPosition });
    }

    const positions = rows.map((r) => r.position);
    const uniquePositions = new Set(positions);
    if (positions.length !== uniquePositions.size) {
      throw new Error('Duplicate positions found in CSV');
    }

    const driverIds = rows.map((r) => r.driverId);
    const uniqueDrivers = new Set(driverIds);
    if (driverIds.length !== uniqueDrivers.size) {
      throw new Error('Duplicate driver IDs found in CSV');
    }

    return rows;
  }

  /**
   * Transform parsed CSV rows into ImportResultRowDTO array
   */
  transformToImportResults(rows: CSVRow[], raceId: string): ImportResultRowDTO[] {
    return rows.map((row) => ({
      id: uuidv4(),
      raceId,
      driverId: row.driverId,
      position: row.position,
      fastestLap: row.fastestLap,
      incidents: row.incidents,
      startPosition: row.startPosition,
    }));
  }

  /**
   * Parse CSV file content and transform to import results
   * @throws Error with descriptive message if parsing or validation fails
   */
  parseAndTransformCSV(content: string, raceId: string): ImportResultRowDTO[] {
    const rows = this.parseCSV(content);
    return this.transformToImportResults(rows, raceId);
  }
}