/**
 * Report Service
 * Handles API calls for statistical reports and analysis
 */

import api from './api';
import type { CurrencyCode } from '../types';

const API_BASE_URL = import.meta.env.VITE_API_BASE_URL || 'http://localhost:2612/api/v1';

// Report API Response Types
export interface CurrencySummary {
  currency: CurrencyCode;
  total_income: number;
  total_expense: number;
  balance: number;
  count: number;
}

export interface UnifiedSummary {
  target_currency: CurrencyCode;
  total_income: number;
  total_expense: number;
  balance: number;
  conversion_date: string;
}

export interface TransactionSummaryResponse {
  by_currency: CurrencySummary[];
  unified?: UnifiedSummary;
}

export interface CategorySummaryItem {
  category_id: number;
  category_name: string;
  currency?: CurrencyCode;
  total_amount: number;
  count: number;
  percentage: number;
}

export interface CategorySummaryResponse {
  by_currency: CategorySummaryItem[];
  unified?: CategorySummaryItem[];
}

export interface TrendDataPoint {
  Date: string;
  TotalIncome: number;
  TotalExpense: number;
  Balance: number;
  Count: number;
}

export interface TrendDataResponse {
  period: 'day' | 'week' | 'month' | 'year';
  currency?: CurrencyCode;
  data_points: TrendDataPoint[];
}

export interface SummaryParams {
  start_date: string;
  end_date: string;
  target_currency?: CurrencyCode;
  conversion_date?: string;
}

export interface CategoryParams {
  start_date: string;
  end_date: string;
  type: 'income' | 'expense';
  target_currency?: CurrencyCode;
  conversion_date?: string;
}

export interface TrendParams {
  start_date: string;
  end_date: string;
  period: 'day' | 'week' | 'month' | 'year';
  currency?: CurrencyCode;
}

export interface ExportParams {
  start_date: string;
  end_date: string;
  format: 'pdf' | 'excel';
  target_currency?: CurrencyCode;
}

/**
 * Get transaction summary for a date range
 */
export const getTransactionSummary = async (
  params: SummaryParams
): Promise<TransactionSummaryResponse> => {
  const response = await api.get<{ success: boolean; data: TransactionSummaryResponse }>(
    '/reports/summary',
    params as unknown as Record<string, string | number | boolean | undefined>
  );
  if (!response.data) {
    throw new Error('Failed to get transaction summary');
  }
  return response.data;
};

/**
 * Get category summary for a date range
 */
export const getCategorySummary = async (
  params: CategoryParams
): Promise<CategorySummaryResponse> => {
  const response = await api.get<{ success: boolean; data: CategorySummaryResponse }>(
    '/reports/category',
    params as unknown as Record<string, string | number | boolean | undefined>
  );
  if (!response.data) {
    throw new Error('Failed to get category summary');
  }
  return response.data;
};

/**
 * Get trend data for a date range
 */
export const getTrendData = async (
  params: TrendParams
): Promise<TrendDataResponse> => {
  const response = await api.get<{ success: boolean; data: TrendDataResponse }>(
    '/reports/trend',
    params as unknown as Record<string, string | number | boolean | undefined>
  );
  if (!response.data) {
    throw new Error('Failed to get trend data');
  }
  return response.data;
};

/**
 * Export report as PDF or Excel
 * Downloads the file directly to the user's device
 */
export const exportReport = async (params: ExportParams): Promise<void> => {
  // Use fetch directly for blob response
  const response = await fetch(`${API_BASE_URL}/reports/export`, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
    },
    body: JSON.stringify(params),
  });

  if (!response.ok) {
    const errorData = await response.json().catch(() => ({}));
    throw new Error(errorData.message || `Export failed with status: ${response.status}`);
  }

  // Get the blob from response
  const blob = await response.blob();

  // Create a temporary URL for the blob
  const url = window.URL.createObjectURL(blob);

  // Create a temporary anchor element and trigger download
  const link = document.createElement('a');
  link.href = url;

  // Generate filename based on date range and format
  const filename = `report_${params.start_date.replace(/-/g, '')}_to_${params.end_date.replace(/-/g, '')}.${params.format === 'pdf' ? 'pdf' : 'xlsx'}`;
  link.download = filename;

  // Trigger the download
  document.body.appendChild(link);
  link.click();

  // Clean up
  document.body.removeChild(link);
  window.URL.revokeObjectURL(url);
};

export default {
  getTransactionSummary,
  getCategorySummary,
  getTrendData,
  exportReport,
};