import type { NetworkModel } from './inpModel';
import type { SimulationResult } from './types';

interface DxfExportOptions {
  model: NetworkModel;
  simulationResult?: SimulationResult | null;
  scenarioName?: string;
}

/**
 * Generates an AutoCAD ASCII DXF (R12 / AC1009) format drawing file
 * with organized CAD layers for pipes, nodes, text labels, and hydraulic results.
 */
export function generateDxf({
  model,
  simulationResult,
  scenarioName = 'Baseline',
}: DxfExportOptions): string {
  const lines: string[] = [];

  const add = (...tokens: (string | number)[]) => {
    for (const t of tokens) {
      lines.push(String(t));
    }
  };

  // Compute model extents to determine appropriate text height and circle radius
  let minX = Infinity, minY = Infinity, maxX = -Infinity, maxY = -Infinity;
  for (const n of Object.values(model.nodes)) {
    if (n.x < minX) minX = n.x;
    if (n.y < minY) minY = n.y;
    if (n.x > maxX) maxX = n.x;
    if (n.y > maxY) maxY = n.y;
  }
  if (minX === Infinity) {
    minX = 0; minY = 0; maxX = 100; maxY = 100;
  }

  const modelSpan = Math.max(maxX - minX, maxY - minY) || 100;
  const textHeight = Math.max(0.5, Math.round((modelSpan * 0.015) * 10) / 10);
  const nodeRadius = Math.max(0.6, Math.round((modelSpan * 0.018) * 10) / 10);

  // 1. HEADER SECTION
  add('0', 'SECTION');
  add('2', 'HEADER');
  add('9', '$ACADVER', '1', 'AC1009'); // AutoCAD Release 12 DXF standard
  add('9', '$INSUNITS', '70', '6');   // Meters (or Unitless)
  add('0', 'ENDSEC');

  // 2. TABLES SECTION (Standard Engineering Layer Definitions)
  add('0', 'SECTION');
  add('2', 'TABLES');
  add('0', 'TABLE');
  add('2', 'LAYER');
  add('70', '7');

  const defineLayer = (name: string, color: number) => {
    add('0', 'LAYER');
    add('2', name);
    add('70', '0');
    add('62', color); // AutoCAD ACI Color
    add('6', 'CONTINUOUS');
  };

  defineLayer('PIPE', 4);           // Cyan
  defineLayer('PIPE_TEXT', 3);      // Green (ID, Dia, Len)
  defineLayer('PIPE_FLOW', 2);      // Yellow (Q, V)
  defineLayer('NODE', 1);           // Red
  defineLayer('NODE_TEXT', 7);      // White/Black (ID, Elev)
  defineLayer('NODE_PRESS', 5);     // Blue (P)
  defineLayer('FACILITY', 6);       // Magenta (Reservoir, Tank)

  add('0', 'ENDTAB');
  add('0', 'ENDSEC');

  // 3. BLOCKS SECTION (Empty but required)
  add('0', 'SECTION');
  add('2', 'BLOCKS');
  add('0', 'ENDSEC');

  // 4. ENTITIES SECTION
  add('0', 'SECTION');
  add('2', 'ENTITIES');

  // Title Text entity
  add('0', 'TEXT');
  add('8', 'NODE_TEXT');
  add('10', minX, '20', maxY + textHeight * 3, '30', '0.0');
  add('40', textHeight * 1.5);
  add('1', `spipe Network Drawing - ${scenarioName}`);
  add('50', '0.0');

  // A. Export Nodes (Junctions, Reservoirs, Tanks)
  for (const node of Object.values(model.nodes)) {
    const isFacility = node.type === 'RESERVOIR' || node.type === 'TANK';
    const layer = isFacility ? 'FACILITY' : 'NODE';
    const r = isFacility ? nodeRadius * 1.6 : nodeRadius;

    // Node Circle entity
    add('0', 'CIRCLE');
    add('8', layer);
    add('10', node.x.toFixed(3), '20', node.y.toFixed(3), '30', '0.0');
    add('40', r.toFixed(3));

    // Node ID and Elevation Text entity
    const elevStr = `EL.${node.elevation.toFixed(1)}`;
    add('0', 'TEXT');
    add('8', 'NODE_TEXT');
    add('10', (node.x + r * 1.2).toFixed(3), '20', (node.y + r * 0.4).toFixed(3), '30', '0.0');
    add('40', textHeight.toFixed(3));
    add('1', `${node.id} (${elevStr})`);
    add('50', '0.0');

    // Hydraulic Pressure Text entity
    if (simulationResult) {
      const res = simulationResult.nodes[node.id];
      if (res) {
        const pressUnit = simulationResult.units.pressure;
        const pressStr = `P=${res.pressure.toFixed(1)}${pressUnit}`;
        add('0', 'TEXT');
        add('8', 'NODE_PRESS');
        add('10', (node.x + r * 1.2).toFixed(3), '20', (node.y - r * 1.0).toFixed(3), '30', '0.0');
        add('40', (textHeight * 0.9).toFixed(3));
        add('1', pressStr);
        add('50', '0.0');
      }
    }
  }

  // B. Export Pipes and Pumps
  for (const pipe of Object.values(model.pipes)) {
    const n1 = model.nodes[pipe.node1];
    const n2 = model.nodes[pipe.node2];
    if (!n1 || !n2) continue;

    // Pipe Line entity
    add('0', 'LINE');
    add('8', 'PIPE');
    add('10', n1.x.toFixed(3), '20', n1.y.toFixed(3), '30', '0.0');
    add('11', n2.x.toFixed(3), '21', n2.y.toFixed(3), '31', '0.0');

    // Pipe Midpoint and Angle
    const midX = (n1.x + n2.x) / 2;
    const midY = (n1.y + n2.y) / 2;
    let angleDeg = Math.atan2(n2.y - n1.y, n2.x - n1.x) * (180 / Math.PI);
    if (angleDeg < -90) angleDeg += 180;
    if (angleDeg > 90) angleDeg -= 180;

    // Pipe Annotation Text: ID, Diameter, Length
    const diaStr = `D${pipe.diameter}`;
    const lenStr = `L${Math.round(pipe.length)}`;
    add('0', 'TEXT');
    add('8', 'PIPE_TEXT');
    add('10', midX.toFixed(3), '20', (midY + textHeight * 0.4).toFixed(3), '30', '0.0');
    add('40', (textHeight * 0.85).toFixed(3));
    add('1', `${pipe.id}:${diaStr}-${lenStr}`);
    add('50', angleDeg.toFixed(1));

    // Hydraulic Flow and Velocity Text entity
    if (simulationResult) {
      const res = simulationResult.links[pipe.id];
      if (res) {
        const flowStr = `Q=${res.flow.toFixed(1)} V=${res.velocity.toFixed(2)}`;
        add('0', 'TEXT');
        add('8', 'PIPE_FLOW');
        add('10', midX.toFixed(3), '20', (midY - textHeight * 1.2).toFixed(3), '30', '0.0');
        add('40', (textHeight * 0.75).toFixed(3));
        add('1', flowStr);
        add('50', angleDeg.toFixed(1));
      }
    }
  }

  add('0', 'ENDSEC');
  add('0', 'EOF');

  return lines.join('\r\n');
}