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package org.jooby.internal.apitool;

import org.jooby.Route;
import static org.jooby.internal.apitool.Filters.routeGroupOwner;
import static org.jooby.internal.apitool.Insn.ldcFor;
import org.objectweb.asm.Handle;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;
import org.objectweb.asm.tree.InvokeDynamicInsnNode;
import org.objectweb.asm.tree.MethodInsnNode;
import org.objectweb.asm.tree.MethodNode;

import java.util.Arrays;
import java.util.List;
import java.util.Optional;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.function.Predicate;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
import java.util.stream.Stream;

class Lambda {
    public final String name;
    public final String pattern;
    public final String desc;
    public final String implementationName;
    public final String owner;
    public final String declaringClass;
    public final Optional<MethodNode> method;
    public final String tag;

    private Lambda(String declaringClass, MethodInsnNode method, Handle h) {
        this(declaringClass, h.getOwner(), h.getDesc(), h.getName(), method.name, null, null);
    }

    private Lambda(String declaringClass, String owner, String desc, String implementationName, String name,
            String pattern, MethodNode method) {
        this(declaringClass, owner, desc, implementationName, name, pattern, method, null);
    }

    private Lambda(String declaringClass, String owner, String desc, String implementationName, String name,
            String pattern, MethodNode method, String tag) {
        this.declaringClass = declaringClass;
        this.owner = owner;
        this.desc = desc;
        this.implementationName = implementationName;
        this.name = name.equals("use") || name.equals("all") ? "*" : name;
        this.pattern = pattern;
        this.method = Optional.ofNullable(method);
        this.tag = tag;
    }

    @Override
    public String toString() {
        return name + " " + pattern;
    }

    /**
     * Creates a new lambda and set a pattern prefix.
     *
     * @param prefix Prefix.
     * @return A new lambda.
     */
    public Lambda prefix(String prefix) {
        return new Lambda(declaringClass, owner, desc, implementationName, name,
                Route.normalize(prefix + "/" + pattern), method.orElse(null), tag);
    }

    public Lambda tag(String tag) {
        if (this.tag != null || tag.startsWith("/:") || tag.startsWith("/{")) {
            // NOOP, keep the most specific
            return this;
        }
        return new Lambda(declaringClass, owner, desc, implementationName, name, pattern, method.orElse(null), tag);
    }

    /**
     * Creates a new lambda and set a pattern prefix.
     *
     * @param method Method node.
     * @return A new lambda.
     */
    public Lambda method(MethodNode method) {
        return new Lambda(declaringClass, owner, desc, implementationName, name, pattern, method, tag);
    }

    public static Stream<Lambda> create(String owner, Optional<String> prefix, MethodInsnNode method,
            MethodNode implementation) {
        List<String> patterns = Insn.ldcFor(method).stream().map(it -> it.cst.toString())
                .collect(Collectors.toList());
        if (patterns.size() == 0) {
            patterns.add("/");
        }
        prefix.ifPresent(p -> {
            IntStream.range(0, patterns.size())
                    .forEach(i -> patterns.set(i, Route.normalize(p + "/" + patterns.get(i))));
        });
        return patterns.stream().map(pattern -> {
            return new Lambda(owner, owner, implementation.desc, implementation.name,
                    method.name.replace("$default", ""), pattern, implementation);
        });
    }

    public static Stream<Lambda> create(ClassLoader loader, Predicate<MethodInsnNode> scriptRoute,
            String declaringClass, InvokeDynamicInsnNode node, MethodNode implementation) {
        return new Insn<>(null, node).next().filter(Filters.is(MethodInsnNode.class)).findFirst()
                .map(MethodInsnNode.class::cast).filter(scriptRoute).map(method -> {
                    return Arrays.asList(node.bsmArgs).stream().filter(Handle.class::isInstance)
                            .map(Handle.class::cast).findFirst().map(handle -> {

                                Lambda lambda = new Lambda(declaringClass, method, handle);
                                // Collect pattern
                                List<Type> args = Arrays.asList(Type.getArgumentTypes(method.desc));
                                AtomicInteger count = new AtomicInteger(IntStream.range(0, args.size())
                                        .filter(i -> !args.get(i).getClassName().equals(String.class.getName()))
                                        .findFirst().orElse(0));
                                int from = 0;
                                // use(verb, pattern)
                                if ("use".equals(method.name) && count.get() == 2) {
                                    from += 1;
                                }

                                MethodInsnNode start = method;

                                // Instance method reference but not Static method reference:
                                if ((!method.owner.equals(lambda.owner)
                                        && handle.getTag() != Opcodes.H_INVOKESTATIC)
                                        && !routeGroupOwner().test(method)) {
                                    // get("pattern", instance::methodReference)
                                    start = new Insn<>(null, method.getPrevious()).prev()
                                            .filter(Filters.is(MethodInsnNode.class)).findFirst()
                                            .map(MethodInsnNode.class::cast).orElse(method);
                                }

                                List<String> ldc = ldcFor(start).stream()
                                        .map(it -> Route.normalize(it.cst.toString())).collect(Collectors.toList());

                                if (routeGroupOwner().test(method)) {
                                    // use("/pattern")
                                    //  .get(pattern?, () -> {});
                                    new Insn<>(null, method).prev().filter(Filters.is(MethodInsnNode.class))
                                            .map(MethodInsnNode.class::cast)
                                            .filter(Filters.call(loader, lambda.owner, "use", String.class))
                                            .findFirst().ifPresent(use -> {
                                                List<String> prefix = ldcFor(use).stream()
                                                        .map(it -> Route.normalize(it.cst.toString()))
                                                        .collect(Collectors.toList());
                                                if (ldc.size() == 0) {
                                                    count.incrementAndGet();
                                                    ldc.add("");
                                                }
                                                IntStream.range(0, ldc.size())
                                                        .forEach(i -> ldc.set(i, prefix.get(0) + ldc.get(i)));
                                            });
                                }
                                if (ldc.size() == 0) {
                                    // default path:
                                    ldc.add("/");
                                    count.incrementAndGet();
                                }
                                return ldc.stream().skip(from).limit(Math.min(count.get(), ldc.size()))
                                        .flatMap(pattern -> Stream.of(new Lambda(lambda.declaringClass,
                                                lambda.owner, lambda.desc, lambda.implementationName, lambda.name,
                                                pattern, implementation)));
                            }).orElse(Stream.of());
                }).orElse(Stream.of());
    }
}