/*
 * This file is part of ComputerCraft - http://www.computercraft.info
 * Copyright Daniel Ratcliffe, 2011-2022. Do not distribute without permission.
 * Send enquiries to dratcliffe@gmail.com
 */
package dan200.computercraft.core.computer;

import dan200.computercraft.api.filesystem.WritableMount;
import dan200.computercraft.api.lua.IArguments;
import dan200.computercraft.api.lua.ILuaAPI;
import dan200.computercraft.api.lua.LuaException;
import dan200.computercraft.api.lua.LuaFunction;
import dan200.computercraft.core.ComputerContext;
import dan200.computercraft.core.CoreConfig;
import dan200.computercraft.core.computer.mainthread.MainThread;
import dan200.computercraft.core.terminal.Terminal;
import dan200.computercraft.test.core.computer.BasicEnvironment;
import dan200.computercraft.test.core.filesystem.MemoryMount;
import dan200.computercraft.test.core.filesystem.ReadOnlyWritableMount;
import org.junit.jupiter.api.Assertions;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Arrays;
import java.util.concurrent.TimeUnit;
import java.util.function.Consumer;

/**
 * Helper class to run a program on a computer.
 */
public class ComputerBootstrap {
    private static final Logger LOG = LoggerFactory.getLogger(ComputerBootstrap.class);
    private static final int TPS = 20;
    public static final int MAX_TIME = 10;

    public static void run(String program, Consumer<Computer> setup, int maxTimes) {
        var mount = new MemoryMount()
            .addFile("test.lua", program)
            .addFile("startup.lua", "assertion.assert(pcall(loadfile('test.lua', nil, _ENV))) os.shutdown()");

        run(new ReadOnlyWritableMount(mount), setup, maxTimes);
    }

    public static void run(String program, int maxTimes) {
        run(program, x -> {
        }, maxTimes);
    }

    public static void run(WritableMount mount, Consumer<Computer> setup, int maxTicks) {
        CoreConfig.maxMainComputerTime = CoreConfig.maxMainGlobalTime = Integer.MAX_VALUE;

        var term = new Terminal(51, 19, true);
        var mainThread = new MainThread();
        var environment = new BasicEnvironment(mount);
        var context = new ComputerContext(environment, 1, mainThread);
        final var computer = new Computer(context, environment, term, 0);

        var api = new AssertApi();
        computer.addApi(api);

        setup.accept(computer);

        try {
            computer.turnOn();
            var everOn = false;

            for (var tick = 0; tick < TPS * maxTicks; tick++) {
                var start = System.currentTimeMillis();

                computer.tick();
                mainThread.tick();

                if (api.message != null) {
                    LOG.debug("Shutting down due to error");
                    computer.shutdown();
                    Assertions.fail(api.message);
                    return;
                }

                var remaining = (1000 / TPS) - (System.currentTimeMillis() - start);
                if (remaining > 0) Thread.sleep(remaining);

                // Break if the computer was once on, and is now off.
                everOn |= computer.isOn();
                if ((everOn || tick > TPS) && !computer.isOn()) break;
            }

            if (computer.isOn() || !api.didAssert) {
                var builder = new StringBuilder().append("Did not correctly [");
                if (!api.didAssert) builder.append(" assert");
                if (computer.isOn()) builder.append(" shutdown");
                builder.append(" ]\n");

                for (var line = 0; line < 19; line++) {
                    builder.append(String.format("%2d | %" + term.getWidth() + "s |\n", line + 1, term.getLine(line)));
                }

                computer.shutdown();
                Assertions.fail(builder.toString());
            }
        } catch (InterruptedException ignored) {
            Thread.currentThread().interrupt();
        } finally {
            try {
                context.ensureClosed(1, TimeUnit.SECONDS);
            } catch (InterruptedException e) {
                throw new IllegalStateException("Runtime thread was interrupted", e);
            }
        }
    }

    public static class AssertApi implements ILuaAPI {
        boolean didAssert;
        String message;

        @Override
        public String[] getNames() {
            return new String[]{ "assertion" };
        }

        @LuaFunction
        public final void log(IArguments arguments) {
            LOG.info("[Computer] {}", Arrays.toString(arguments.getAll()));
        }

        @LuaFunction("assert")
        public final Object[] doAssert(IArguments arguments) throws LuaException {
            didAssert = true;

            var arg = arguments.get(0);
            if (arg == null || arg == Boolean.FALSE) {
                message = arguments.optString(1, "Assertion failed");
                throw new LuaException(message);
            }

            return arguments.getAll();
        }
    }
}