/**
 * Import Service – handles DXF, SVG, PDF, JSON imports
 */
import { parseDXF, type DXFImportResult } from './dxfParser';
import type { CADElement, CADLayer, BlockDefinition, ProjectData } from '../types/cad.types';

export interface ImportResult {
  success: boolean;
  elements: CADElement[];
  layers?: CADLayer[];
  blocks?: BlockDefinition[];
  warnings: string[];
  error?: string;
}

let idCounter = 0;
const nextId = () => `imp-${Date.now()}-${idCounter++}`;

/**
 * Import a file based on its extension.
 */
export async function importFile(file: File): Promise<ImportResult> {
  const ext = file.name.split('.').pop()?.toLowerCase();
  const text = await file.text();

  switch (ext) {
    case 'dxf':
      return importDXF(text);
    case 'svg':
      return importSVG(text);
    case 'json':
      return importJSON(text);
    case 'pdf':
      return { success: false, elements: [], warnings: ['PDF import not yet supported'] };
    default:
      return { success: false, elements: [], warnings: [`Unsupported format: ${ext}`] };
  }
}

/**
 * Import DXF string.
 */
export function importDXF(dxfString: string): ImportResult {
  try {
    const result: DXFImportResult = parseDXF(dxfString);
    return {
      success: true,
      elements: result.elements,
      layers: result.layers,
      warnings: result.warnings,
    };
  } catch (err) {
    return {
      success: false,
      elements: [],
      warnings: [],
      error: `DXF parse error: ${err instanceof Error ? err.message : String(err)}`,
    };
  }
}

/**
 * Import SVG string — converts SVG elements to CAD elements.
 */
export function importSVG(svgString: string): ImportResult {
  try {
    const parser = new DOMParser();
    const doc = parser.parseFromString(svgString, 'image/svg+xml');
    const svg = doc.documentElement;
    const elements: CADElement[] = [];
    const warnings: string[] = [];

    // Parse SVG viewBox for coordinate mapping
    const viewBox = svg.getAttribute('viewBox');
    let vbX = 0, vbY = 0;
    if (viewBox) {
      const parts = viewBox.split(/[\s,]+/).map(Number);
      vbX = parts[0] || 0;
      vbY = parts[1] || 0;
    }

    // Process SVG elements
    const processElement = (node: Element) => {
      const tag = node.tagName.toLowerCase();
      const stroke = node.getAttribute('stroke') || '#ffffff';
      const strokeWidth = parseFloat(node.getAttribute('stroke-width') || '1');
      const fill = node.getAttribute('fill') || 'none';

      switch (tag) {
        case 'line': {
          const x1 = parseFloat(node.getAttribute('x1') || '0') - vbX;
          const y1 = parseFloat(node.getAttribute('y1') || '0') - vbY;
          const x2 = parseFloat(node.getAttribute('x2') || '0') - vbX;
          const y2 = parseFloat(node.getAttribute('y2') || '0') - vbY;
          elements.push({
            id: nextId(), type: 'line', layerId: 'layer-0',
            x: Math.min(x1, x2), y: Math.min(y1, y2),
            width: Math.abs(x2 - x1), height: Math.abs(y2 - y1),
            properties: { stroke, strokeWidth, x1, y1, x2, y2 },
          });
          break;
        }
        case 'rect': {
          const x = parseFloat(node.getAttribute('x') || '0') - vbX;
          const y = parseFloat(node.getAttribute('y') || '0') - vbY;
          const w = parseFloat(node.getAttribute('width') || '0');
          const h = parseFloat(node.getAttribute('height') || '0');
          elements.push({
            id: nextId(), type: 'rect', layerId: 'layer-0',
            x, y, width: w, height: h,
            properties: { stroke, strokeWidth, fill: fill !== 'none' ? fill : undefined },
          });
          break;
        }
        case 'circle': {
          const cx = parseFloat(node.getAttribute('cx') || '0') - vbX;
          const cy = parseFloat(node.getAttribute('cy') || '0') - vbY;
          const r = parseFloat(node.getAttribute('r') || '0');
          elements.push({
            id: nextId(), type: 'circle', layerId: 'layer-0',
            x: cx - r, y: cy - r, width: r * 2, height: r * 2,
            properties: { stroke, strokeWidth, radius: r },
          });
          break;
        }
        case 'ellipse': {
          const cx = parseFloat(node.getAttribute('cx') || '0') - vbX;
          const cy = parseFloat(node.getAttribute('cy') || '0') - vbY;
          const rx = parseFloat(node.getAttribute('rx') || '0');
          const ry = parseFloat(node.getAttribute('ry') || '0');
          elements.push({
            id: nextId(), type: 'circle', layerId: 'layer-0',
            x: cx - rx, y: cy - ry, width: rx * 2, height: ry * 2,
            properties: { stroke, strokeWidth, radius: Math.max(rx, ry) },
          });
          break;
        }
        case 'polyline':
        case 'polygon': {
          const ptsStr = node.getAttribute('points') || '';
          const pts = ptsStr.trim().split(/[\s,]+/).reduce((acc: Array<{x:number;y:number}>, val: string, idx: number) => {
            if (idx % 2 === 0) acc.push({ x: parseFloat(val) - vbX, y: 0 });
            else acc[acc.length - 1].y = parseFloat(val) - vbY;
            return acc;
          }, []);
          if (pts.length >= 2) {
            const minX = Math.min(...pts.map(p => p.x));
            const minY = Math.min(...pts.map(p => p.y));
            const maxX = Math.max(...pts.map(p => p.x));
            const maxY = Math.max(...pts.map(p => p.y));
            elements.push({
              id: nextId(), type: tag === 'polygon' ? 'polygon' : 'polyline', layerId: 'layer-0',
              x: minX, y: minY, width: maxX - minX, height: maxY - minY,
              properties: { stroke, strokeWidth, points: pts },
            });
          }
          break;
        }
        case 'text': {
          const x = parseFloat(node.getAttribute('x') || '0') - vbX;
          const y = parseFloat(node.getAttribute('y') || '0') - vbY;
          const fontSize = parseFloat(node.getAttribute('font-size') || '12');
          const text = node.textContent || '';
          elements.push({
            id: nextId(), type: 'text', layerId: 'layer-0',
            x, y, width: 0, height: 0,
            properties: { stroke, strokeWidth, text, fontSize },
          });
          break;
        }
        case 'g': {
          // Process group children
          Array.from(node.children).forEach(processElement);
          break;
        }
        default:
          warnings.push(`Unsupported SVG element: ${tag}`);
      }
    };

    Array.from(svg.children).forEach(processElement);

    return { success: true, elements, warnings };
  } catch (err) {
    return {
      success: false, elements: [], warnings: [],
      error: `SVG parse error: ${err instanceof Error ? err.message : String(err)}`,
    };
  }
}

/**
 * Import JSON project file.
 */
export function importJSON(jsonString: string): ImportResult {
  try {
    const data: ProjectData = JSON.parse(jsonString);
    return {
      success: true,
      elements: data.elements || [],
      layers: data.layers || [],
      blocks: data.blocks || [],
      warnings: [],
    };
  } catch (err) {
    return {
      success: false, elements: [], warnings: [],
      error: `JSON parse error: ${err instanceof Error ? err.message : String(err)}`,
    };
  }
}