package examples;

import java.util.UUID;
import neqsim.process.equipment.pipeline.TwoFluidPipe;
import neqsim.process.equipment.stream.Stream;
import neqsim.thermo.system.SystemInterface;
import neqsim.thermo.system.SystemSrkEos;

/**
 * Example demonstrating the two-fluid transient multiphase pipe model.
 * 
 * <p>
 * This example simulates gas-condensate flow through a 10 km pipeline with
 * terrain undulations,
 * demonstrating liquid accumulation in low points.
 * </p>
 * 
 * <p>
 * The two-fluid model solves separate mass and momentum equations for each
 * phase, enabling accurate
 * prediction of:
 * </p>
 * <ul>
 * <li>Liquid holdup profile along the pipeline</li>
 * <li>Slug formation and dynamics</li>
 * <li>Pressure drop with terrain effects</li>
 * <li>Transient ramp-up and turndown behavior</li>
 * </ul>
 * 
 * @author NeqSim Team
 * @version 1.0
 */
public class TwoFluidPipeExample {

  /**
   * Main entry point.
   * 
   * @param args Command line arguments (not used)
   */
  public static void main(String[] args) {
    // Example 1: Simple steady-state simulation
    System.out.println("=== Example 1: Steady-State Pipeline Simulation ===\n");
    runSteadyStateExample();

    // Example 2: Transient ramp-up simulation
    System.out.println("\n=== Example 2: Transient Ramp-Up Simulation ===\n");
    runTransientExample();

    // Example 3: Terrain-induced liquid accumulation
    System.out.println("\n=== Example 3: Terrain Effects on Liquid Holdup ===\n");
    runTerrainExample();
  }

  /**
   * Demonstrates steady-state simulation of a horizontal pipeline.
   */
  public static void runSteadyStateExample() {
    // Create a gas-condensate fluid
    SystemInterface fluid = new SystemSrkEos(288.15, 80.0); // 15°C, 80 bar
    fluid.addComponent("nitrogen", 0.02);
    fluid.addComponent("CO2", 0.01);
    fluid.addComponent("methane", 0.80);
    fluid.addComponent("ethane", 0.06);
    fluid.addComponent("propane", 0.04);
    fluid.addComponent("n-butane", 0.03);
    fluid.addComponent("n-pentane", 0.02);
    fluid.addComponent("n-hexane", 0.01);
    fluid.addComponent("n-heptane", 0.01);
    fluid.setMixingRule("classic");
    fluid.setMultiPhaseCheck(true);

    // Create inlet stream
    Stream inlet = new Stream("Inlet", fluid);
    inlet.setFlowRate(50.0, "kg/sec"); // 50 kg/s
    inlet.setTemperature(15.0, "C");
    inlet.setPressure(80.0, "bara");
    inlet.run();

    // Create two-fluid pipe
    TwoFluidPipe pipe = new TwoFluidPipe("GasCondensatePipe", inlet);
    pipe.setLength(10000); // 10 km
    pipe.setDiameter(0.4); // 400 mm ID
    pipe.setNumberOfSections(200);
    pipe.setRoughness(4.5e-5); // Steel pipe roughness (45 µm)

    // Run steady-state
    pipe.run();

    // Report results
    double[] pressures = pipe.getPressureProfile();
    double[] holdups = pipe.getLiquidHoldupProfile();
    double inletP = pressures[0];
    double outletP = pressures[pressures.length - 1];

    System.out.println("Pipeline Configuration:");
    System.out.printf("  Length: %.0f m%n", 10000.0);
    System.out.printf("  Diameter: %.0f mm%n", 400.0);
    System.out.printf("  Mass flow: %.1f kg/s%n", 50.0);
    System.out.println();
    System.out.println("Steady-State Results:");
    System.out.printf("  Inlet pressure:  %.2f bara%n", inletP / 1e5);
    System.out.printf("  Outlet pressure: %.2f bara%n", outletP / 1e5);
    System.out.printf("  Pressure drop:   %.2f bar%n", (inletP - outletP) / 1e5);
    System.out.printf("  Liquid inventory: %.2f m³%n", pipe.getLiquidInventory("m3"));
  }

  /**
   * Demonstrates transient ramp-up from turndown to normal rate.
   */
  public static void runTransientExample() {
    // Create simple two-phase fluid
    SystemInterface fluid = new SystemSrkEos(300.0, 50.0);
    fluid.addComponent("methane", 0.90);
    fluid.addComponent("n-pentane", 0.10);
    fluid.setMixingRule("classic");
    fluid.setMultiPhaseCheck(true);

    // Start at low flow (turndown condition)
    Stream inlet = new Stream("Inlet", fluid);
    inlet.setFlowRate(5.0, "kg/sec"); // Turndown rate
    inlet.run();

    // Create pipe
    TwoFluidPipe pipe = new TwoFluidPipe("TransientPipe", inlet);
    pipe.setLength(5000);
    pipe.setDiameter(0.3);
    pipe.setNumberOfSections(100);
    pipe.run();

    double initialInventory = pipe.getLiquidInventory("m3");
    System.out.printf("Initial liquid inventory (turndown): %.2f m³%n", initialInventory);

    // Ramp up to normal rate over 10 minutes
    UUID runId = UUID.randomUUID();
    double dt = 1.0; // 1 second timestep
    double rampDuration = 600; // 10 minutes

    for (double t = 0; t < rampDuration; t += dt) {
      // Linear ramp from 5 to 50 kg/s
      double flowRate = 5.0 + (50.0 - 5.0) * (t / rampDuration);
      inlet.setFlowRate(flowRate, "kg/sec");
      inlet.run();

      pipe.runTransient(dt, runId);

      // Report every minute
      if (Math.abs(t % 60.0) < dt / 2) {
        double inventory = pipe.getLiquidInventory("m3");
        System.out.printf("  t=%.0f s: Flow=%.1f kg/s, Inventory=%.2f m³%n", t, flowRate,
            inventory);
      }
    }

    double finalInventory = pipe.getLiquidInventory("m3");
    System.out.printf("Final liquid inventory (normal rate): %.2f m³%n", finalInventory);
    System.out.printf("Inventory change: %.2f m³%n", finalInventory - initialInventory);
  }

  /**
   * Demonstrates terrain-induced liquid accumulation.
   */
  public static void runTerrainExample() {
    // Create gas-dominated fluid with some liquid
    SystemInterface fluid = new SystemSrkEos(293.15, 60.0);
    fluid.addComponent("methane", 0.95);
    fluid.addComponent("n-heptane", 0.05);
    fluid.setMixingRule("classic");
    fluid.setMultiPhaseCheck(true);

    Stream inlet = new Stream("Inlet", fluid);
    inlet.setFlowRate(20.0, "kg/sec");
    inlet.run();

    // Create pipe with terrain profile
    TwoFluidPipe pipe = new TwoFluidPipe("TerrainPipe", inlet);
    pipe.setLength(5000);
    pipe.setDiameter(0.25);
    int nSections = 100;
    pipe.setNumberOfSections(nSections);

    // Create terrain with a valley (low point accumulation)
    double[] elevations = new double[nSections];
    for (int i = 0; i < nSections; i++) {
      double x = (double) i / (nSections - 1);
      // Valley profile: drops 50m then rises back
      if (x < 0.4) {
        elevations[i] = -50.0 * (x / 0.4);
      } else if (x < 0.6) {
        elevations[i] = -50.0;
      } else {
        elevations[i] = -50.0 * (1.0 - (x - 0.6) / 0.4);
      }
    }
    pipe.setElevationProfile(elevations);

    // Run simulation
    pipe.run();

    // Report holdup profile
    double[] holdups = pipe.getLiquidHoldupProfile();
    System.out.println("Terrain Profile and Liquid Holdup:");
    System.out.println("Position [m]  Elevation [m]  Holdup [-]");

    for (int i = 0; i < nSections; i += 10) {
      double position = i * 5000.0 / (nSections - 1);
      System.out.printf("  %7.0f      %7.1f        %.4f%n", position, elevations[i], holdups[i]);
    }

    // Identify liquid accumulation zone
    double maxHoldup = 0;
    int maxLocation = 0;
    for (int i = 0; i < holdups.length; i++) {
      if (holdups[i] > maxHoldup) {
        maxHoldup = holdups[i];
        maxLocation = i;
      }
    }

    double maxPosition = maxLocation * 5000.0 / (nSections - 1);
    System.out.printf("%nMaximum holdup: %.4f at position %.0f m (valley bottom)%n", maxHoldup,
        maxPosition);
    System.out.printf("Total liquid inventory: %.2f m³%n", pipe.getLiquidInventory("m3"));
  }
}