import megamek.client.ui.clientGUI.calculationReport.TextCalculationReport;
import megamek.common.loaders.MekSummary;
import megamek.common.loaders.MekSummaryCache;
import megamek.common.units.Entity;

import java.io.BufferedWriter;
import java.io.FileOutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.nio.charset.StandardCharsets;

/**
 * Dump the working of MegaMek's C-bill cost calculation, one object per unit.
 *
 * <p>The same bargain as DumpBv: `DumpUnits` already carries the answer, and
 * an answer alone makes a poor oracle for a reimplementation. A design's cost
 * is a sum of two dozen terms - the frame, the engine, each actuator, each
 * weapon, the plate - multiplied by a factor for the kind of machine it is,
 * and a total that is 40,000 C-bills light says nothing about which term is
 * wrong. `Entity.getCost` writes its own working into a report as it goes,
 * and that report says which line.
 *
 *   java -cp "MegaMek.jar:lib/*" DumpCost.java out.jsonl [unitType ...]
 *
 * Must run with MegaMek's install dir as the working directory.
 */
public final class DumpCost {

    public static void main(String[] args) throws Exception {
        if (args.length < 1) {
            System.err.println("usage: DumpCost <out.jsonl> [unitType ...]");
            System.exit(2);
        }
        java.util.Set<String> only = new java.util.LinkedHashSet<>();
        for (int i = 1; i < args.length; i++) {
            only.add(args[i].toLowerCase(java.util.Locale.ROOT));
        }

        long start = System.currentTimeMillis();
        MekSummaryCache cache = MekSummaryCache.getInstance();
        long deadline = start + 600_000L;
        while (!cache.isInitialized()) {
            if (System.currentTimeMillis() > deadline) {
                System.err.println("units.cache did not initialise within 600s");
                System.exit(1);
            }
            Thread.sleep(250L);
        }

        int written = 0;
        int skipped = 0;
        try (PrintWriter out = new PrintWriter(new BufferedWriter(
                new OutputStreamWriter(new FileOutputStream(args[0]), StandardCharsets.UTF_8)))) {
            for (MekSummary ms : cache.getAllMeks()) {
                String name = ms.getName();
                try {
                    if (!only.isEmpty()
                            && !only.contains(ms.getUnitType().toLowerCase(java.util.Locale.ROOT))) {
                        continue;
                    }
                    Entity entity = ms.loadEntity();
                    if (entity == null) {
                        skipped++;
                        continue;
                    }
                    TextCalculationReport report = new TextCalculationReport();
                    // `false` is "count the ammunition", which is what
                    // MekSummary.cost records and so what helm is measured
                    // against.
                    double cost = entity.getCost(report, false);

                    StringBuilder sb = new StringBuilder(1024);
                    sb.append('{');
                    str(sb, "name");
                    sb.append(':');
                    str(sb, name);
                    sb.append(',');
                    str(sb, "unitType");
                    sb.append(':');
                    str(sb, ms.getUnitType());
                    sb.append(',');
                    str(sb, "cost");
                    sb.append(':');
                    sb.append(Double.isFinite(cost) ? Double.toString(cost) : "null");
                    sb.append(',');
                    str(sb, "summaryCost");
                    sb.append(':');
                    double summary = ms.getCost();
                    sb.append(Double.isFinite(summary) ? Double.toString(summary) : "null");
                    sb.append(',');
                    // What the design's own kind multiplies the sum by, which
                    // the report prints but not always as a line of its own.
                    str(sb, "priceMultiplier");
                    sb.append(':');
                    double multiplier = entity.getPriceMultiplier();
                    sb.append(Double.isFinite(multiplier) ? Double.toString(multiplier) : "null");
                    sb.append(',');
                    str(sb, "report");
                    sb.append(':');
                    str(sb, report.toString());
                    sb.append('}');
                    out.println(sb);
                    written++;
                } catch (Throwable t) {
                    skipped++;
                    System.err.println("skipped " + name + ": " + t);
                }
            }
        }

        System.out.printf("dumped %d units in %.1fs (%d skipped) -> %s%n",
                written, (System.currentTimeMillis() - start) / 1000.0, skipped, args[0]);
        System.exit(0);
    }

    private static void str(StringBuilder sb, String s) {
        sb.append('"');
        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
            switch (c) {
                case '"' -> sb.append("\\\"");
                case '\\' -> sb.append("\\\\");
                case '\n' -> sb.append("\\n");
                case '\r' -> sb.append("\\r");
                case '\t' -> sb.append("\\t");
                default -> {
                    if (c < 0x20) {
                        sb.append(String.format("\\u%04x", (int) c));
                    } else {
                        sb.append(c);
                    }
                }
            }
        }
        sb.append('"');
    }
}