frontend/src/utils/csvExport.ts

/** 
 * Utility to export the current project state to a CSV file.
 * Synchronized with the StreamDataTable and ActionBar.
 */

import type { ProjectState } from '../types/project';
import { extractStreamInfo } from './streamInfo';

export function exportProjectToCsv(state: ProjectState) {
  const rows: string[][] = [];
  const header = [
    'Process',
    'Subprocess',
    'Stream Name',
    'Type',
    'Tin',
    'Tout',
    'ṁ',
    'cp',
    'CP',
    'Q (kW)',
    'Lat',
    'Lon',
    'Hours',
    'Water In',
    'Water Out',
    'Density',
    'Pressure',
    'Notes',
  ];
  rows.push(header);

  (state.proc_groups || []).forEach((subIdxs, gIdx) => {
    const gName = state.proc_group_names?.[gIdx] || `Process ${gIdx + 1}`;
    const gCoord = state.proc_group_coordinates?.[gIdx] || {};

    subIdxs.forEach((si) => {
      const sub = state.processes[si];
      if (!sub) return;

      const notes = sub.extra_info?.notes || '';
      const lat = String(sub.lat || gCoord.lat || '');
      const lon = String(sub.lon || gCoord.lon || '');
      const hours = sub.hours || gCoord.hours || '';
      const water_in = sub.extra_info?.water_content_in || '';
      const water_out = sub.extra_info?.water_content_out || '';
      const density = sub.extra_info?.density || '';
      const pressure = sub.extra_info?.pressure || '';

      // Add streams for this subprocess
      if (!sub.streams?.length && !sub.children?.length) {
        rows.push([gName, sub.name, '', '', '', '', '', '', '', '', lat, lon, hours, water_in, water_out, density, pressure, notes]);
      } else {
        (sub.streams || []).forEach((s) => {
          const si = extractStreamInfo(s as any);
          rows.push([
            gName,
            sub.name,
            s.name,
            si.type || '',
            String(si.tin ?? ''),
            String(si.tout ?? ''),
            String(si.mdot ?? ''),
            String(si.cp ?? ''),
            String(si.CP ?? ''),
            si.Q ? si.Q.toFixed(1) : '',
            lat,
            lon,
            hours,
            String(si.water_in || water_in),
            String(si.water_out || water_out),
            String(si.density || density),
            String(si.pressure || pressure),
            notes,
          ]);
        });

        // Also add streams for sub-subprocesses (children)
        (sub.children || []).forEach((child) => {
          const c_notes = child.extra_info?.notes || notes || '';
          const c_lat = String(child.lat || sub.lat || gCoord.lat || '');
          const c_lon = String(child.lon || sub.lon || gCoord.lon || '');
          const c_hours = child.hours || hours || '';
          const c_water_in = child.extra_info?.water_content_in || water_in || '';
          const c_water_out = child.extra_info?.water_content_out || water_out || '';
          const c_density = child.extra_info?.density || density || '';
          const c_pressure = child.extra_info?.pressure || pressure || '';
          const c_name = `${sub.name} › ${child.name}`;

          if (!(child.streams || []).length) {
            rows.push([gName, c_name, '', '', '', '', '', '', '', '', c_lat, c_lon, c_hours, c_water_in, c_water_out, c_density, c_pressure, c_notes]);
          } else {
            (child.streams || []).forEach((s) => {
              const si = extractStreamInfo(s as any);
              rows.push([
                gName,
                c_name,
                s.name,
                si.type || '',
                String(si.tin ?? ''),
                String(si.tout ?? ''),
                String(si.mdot ?? ''),
                String(si.cp ?? ''),
                String(si.CP ?? ''),
                si.Q ? si.Q.toFixed(1) : '',
                c_lat,
                c_lon,
                c_hours,
                String(si.water_in || c_water_in),
                String(si.water_out || c_water_out),
                String(si.density || c_density),
                String(si.pressure || c_pressure),
                c_notes,
              ]);
            });
          }
        });
      }
    });
  });

  const csv = rows.map((r) => r.map((c) => `"${c}"`).join(',')).join('\n');
  const blob = new Blob([csv], { type: 'text/csv' });
  const url = URL.createObjectURL(blob);
  const a = document.createElement('a');
  a.href = url;
  a.download = `heattransplan_export_${new Date().toISOString().slice(0, 10)}.csv`;
  a.click();
  URL.revokeObjectURL(url);
}