import megamek.common.battleValue.BVCalculator;
import megamek.common.loaders.MekSummaryCache;
import megamek.common.units.Entity;
import megamek.common.loaders.MULParser;

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

/**
 * Dump MegaMek's battle value for the units in a `.mul`.
 *
 * <p>The other dumps score a design as it leaves the factory, or a design this
 * program shot at in a way it chose. Neither can answer for a unit somebody
 * else varied: a `.mul` records what is in every critical slot, and MegaMek
 * reads those types back - a magazine whose `type` names inferno rounds is
 * loaded with inferno rounds and scored as such. That is how a player changes
 * a unit without designing one, and it is the case helm has to agree about.
 *
 * <p>Usage: DumpMul out.jsonl file.mul [file.mul ...]
 *
 * <p>Must run with MegaMek's install dir as the working directory. The summary
 * cache has to be up before a `.mul` can name a design.
 */
public final class DumpMul {

    public static void main(String[] args) throws Exception {
        if (args.length < 2) {
            System.err.println("usage: DumpMul <out.jsonl> <file.mul> [file.mul ...]");
            System.exit(2);
        }

        MekSummaryCache cache = MekSummaryCache.getInstance();
        long deadline = System.currentTimeMillis() + 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;
        try (PrintWriter out = new PrintWriter(new BufferedWriter(
                new OutputStreamWriter(new FileOutputStream(args[0]), StandardCharsets.UTF_8)))) {
            for (int i = 1; i < args.length; i++) {
                File file = new File(args[i]);
                MULParser parser = new MULParser(file, null);
                for (Entity entity : parser.getEntities()) {
                    BVCalculator calc = BVCalculator.getBVCalculator(entity);
                    // Crew and C3 left out: the crew is arithmetic helm does
                    // itself from a table, and C3 needs a game to see the
                    // other units. What is being asked here is what the unit
                    // itself is worth once somebody has varied it.
                    int bv = calc.calculateBV(true, true);
                    StringBuilder sb = new StringBuilder(256);
                    sb.append("{\"file\":");
                    quote(sb, file.getName());
                    sb.append(",\"name\":");
                    quote(sb, entity.getShortNameRaw());
                    sb.append(",\"bv\":").append(bv);
                    // Which half is wrong is the first question every
                    // disagreement asks, and the fields are not public.
                    for (String field : new String[] { "defensiveValue", "offensiveValue" }) {
                        try {
                            java.lang.reflect.Field f = findField(calc.getClass(), field);
                            if (f != null) {
                                f.setAccessible(true);
                                sb.append(",\"").append(field).append("\":").append(f.get(calc));
                            }
                        } catch (Throwable ignored) {
                            // A MegaMek that renames these should lose the
                            // columns rather than fail.
                        }
                    }
                    sb.append('}');
                    out.println(sb);
                    written++;
                }
                String warning = parser.getWarningMessage();
                if (warning != null && !warning.isBlank()) {
                    System.err.println(file.getName() + ": " + warning.trim());
                }
            }
        }
        System.err.println("wrote " + written + " rows");
    }

    /** A field on this class or any above it. */
    private static java.lang.reflect.Field findField(Class<?> type, String name) {
        for (Class<?> at = type; at != null; at = at.getSuperclass()) {
            try {
                return at.getDeclaredField(name);
            } catch (NoSuchFieldException ignored) {
                // Keep walking up.
            }
        }
        return null;
    }

    private static void quote(StringBuilder sb, String value) {
        sb.append('"');
        for (int i = 0; i < value.length(); i++) {
            char c = value.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('"');
    }
}