import { AnalysisOptions, AnalysisResult, ApiError, ColumnDetectionResult } from '../types';

const API_BASE = '/api';

async function handleResponse<T>(response: Response): Promise<T> {
  if (!response.ok) {
    let errorData: { detail?: { code: string; message: string; hints: string[] } | string };
    try {
      errorData = await response.json();
    } catch {
      throw { code: 'NETWORK_ERROR', message: `HTTP ${response.status}: ${response.statusText}`, hints: [] } as ApiError;
    }

    const detail = errorData?.detail;
    if (typeof detail === 'object' && detail !== null) {
      throw detail as ApiError;
    }
    throw {
      code: 'API_ERROR',
      message: typeof detail === 'string' ? detail : `Request failed with status ${response.status}`,
      hints: [],
    } as ApiError;
  }

  return response.json() as Promise<T>;
}

export async function analyzeFiles(
  csvFile: File,
  harFile: File,
  options: AnalysisOptions,
  nameCol?: string,
  valueCol?: string
): Promise<AnalysisResult> {
  const formData = new FormData();
  formData.append('csv_file', csvFile);
  formData.append('har_file', harFile);
  formData.append('options_json', JSON.stringify(options));
  if (nameCol) formData.append('name_col', nameCol);
  if (valueCol) formData.append('value_col', valueCol);

  const response = await fetch(`${API_BASE}/analyze`, {
    method: 'POST',
    body: formData,
  });

  return handleResponse<AnalysisResult>(response);
}

export async function loadDemo(): Promise<AnalysisResult> {
  const response = await fetch(`${API_BASE}/demo`);
  return handleResponse<AnalysisResult>(response);
}

export async function detectColumns(csvFile: File): Promise<ColumnDetectionResult> {
  const formData = new FormData();
  formData.append('csv_file', csvFile);

  const response = await fetch(`${API_BASE}/columns`, {
    method: 'POST',
    body: formData,
  });

  return handleResponse<ColumnDetectionResult>(response);
}

export async function exportReport(
  result: AnalysisResult,
  format: 'html' | 'json' | 'csv'
): Promise<void> {
  const response = await fetch(`${API_BASE}/export/${format}`, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify(result),
  });

  if (!response.ok) {
    throw { code: 'EXPORT_ERROR', message: 'Export failed', hints: [] } as ApiError;
  }

  // Trigger download
  const blob = await response.blob();
  const url = URL.createObjectURL(blob);
  const a = document.createElement('a');
  a.href = url;
  const ext = format === 'html' ? 'html' : format === 'json' ? 'json' : 'csv';
  const contentDisp = response.headers.get('Content-Disposition');
  const filename = contentDisp?.match(/filename="?([^"]+)"?/)?.[1] ?? `analysis-report.${ext}`;
  a.download = filename;
  a.click();
  URL.revokeObjectURL(url);
}