package io.gitlab.jfronny.gson.compile.processor.util.valueprocessor;

import io.gitlab.jfronny.gson.compile.processor.util.DelegateList;

import javax.lang.model.element.*;
import javax.lang.model.type.TypeKind;
import javax.lang.model.type.TypeMirror;
import javax.lang.model.util.ElementFilter;
import javax.lang.model.util.Types;
import java.util.*;

public class Properties extends DelegateList<Property<?>> {
    public final List<Property<?>> names;
    public final List<Property.Param> params;
    public final List<Property.Field> fields;
    public final List<Property.Getter> getters;
    public final List<Property.ConstructorParam> constructorParams;
    public final List<Property.BuilderParam> builderParams;

    public static Properties build(Types types, ConstructionSource constructionSource) throws ElementException {
        Builder builder = new Builder(types);
        // constructor params
        for (VariableElement param : constructionSource.getConstructionElement().getParameters()) {
            builder.addConstructorParam(param);
        }

        if (constructionSource instanceof ConstructionSource.Builder csb) {
            var builderClass = csb.getBuilderClass();
            for (ExecutableElement method : ElementFilter.methodsIn(builderClass.getEnclosedElements())) {
                builder.addBuilderParam(builderClass.asType(), method);
            }
        }

        var targetClass = constructionSource.getTargetClass();
        builder.addFieldsAndGetters(targetClass);

        return builder.build();
    }

    private Properties(List<Property<?>> names,
                      List<Property.Param> params,
                      List<Property.Field> fields,
                      List<Property.Getter> getters,
                      List<Property.ConstructorParam> constructorParams,
                      List<Property.BuilderParam> builderParams) {
        super(names);
        this.names = Objects.requireNonNull(names);
        this.params = Objects.requireNonNull(params);
        this.fields = Objects.requireNonNull(fields);
        this.getters = Objects.requireNonNull(getters);
        this.constructorParams = Objects.requireNonNull(constructorParams);
        this.builderParams = Objects.requireNonNull(builderParams);
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) return true;
        if (!(obj instanceof Properties other)) return false;
        return names.equals(other.names);
    }

    @Override
    public int hashCode() {
        return names.hashCode();
    }

    @Override
    public String toString() {
        return names.toString();
    }

    private static class Builder {
        private static final Set<String> METHODS_TO_SKIP = Set.of("hashCode", "toString", "clone");

        private final Types types;
        public final List<Property<?>> names = new ArrayList<>();
        public final List<Property.Param> params = new ArrayList<>();
        public final List<Property.Field> fields = new ArrayList<>();
        public final List<Property.Getter> getters = new ArrayList<>();
        public final List<Property.ConstructorParam> constructorParams = new ArrayList<>();
        public final List<Property.BuilderParam> builderParams = new ArrayList<>();

        public Builder(Types types) {
            this.types = types;
        }

        public void addFieldsAndGetters(TypeElement targetClass) {
            // getters
            for (ExecutableElement method : ElementFilter.methodsIn(targetClass.getEnclosedElements())) {
                addGetter(targetClass, method);
            }

            // fields
            for (VariableElement field : ElementFilter.fieldsIn(targetClass.getEnclosedElements())) {
                addField(field);
            }

            for (TypeMirror superInterface : targetClass.getInterfaces()) {
                addFieldsAndGetters((TypeElement) types.asElement(superInterface));
            }

            TypeMirror superclass = targetClass.getSuperclass();
            if (superclass.getKind() != TypeKind.NONE && !superclass.toString().equals("java.lang.Object")) {
                addFieldsAndGetters((TypeElement) types.asElement(superclass));
            }
        }

        public void addGetter(TypeElement classElement, ExecutableElement method) {
            Set<Modifier> modifiers = method.getModifiers();
            if (modifiers.contains(Modifier.PRIVATE)
                    || modifiers.contains(Modifier.STATIC)
                    || method.getReturnType().getKind() == TypeKind.VOID
                    || !method.getParameters().isEmpty()
                    || isMethodToSkip(classElement, method)) {
                return;
            }
            getters.add(new Property.Getter(method));
        }

        public void addField(VariableElement field) {
            Set<Modifier> modifiers = field.getModifiers();
            if (modifiers.contains(Modifier.STATIC)) return;
            fields.add(new Property.Field(field));
        }

        public void addConstructorParam(VariableElement param) {
            Property.ConstructorParam prop = new Property.ConstructorParam(param);
            constructorParams.add(prop);
            params.add(prop);
        }

        public void addBuilderParam(TypeMirror builderType, ExecutableElement method) {
            if (method.getReturnType().equals(builderType) && method.getParameters().size() == 1) {
                Property.BuilderParam prop = new Property.BuilderParam(method);
                builderParams.add(prop);
                params.add(prop);
            }
        }

        public Properties build() throws ElementException {
            stripBeans(getters);
            removeExtraBuilders();
            removeGettersForTransientFields();
            mergeSerializeNames(params, fields, getters);
            removeExtraFields();
            names.addAll(params);
            fields.stream().filter(f -> !containsName(names, f)).forEach(names::add);
            getters.stream().filter(f -> !containsName(names, f)).forEach(names::add);
            return new Properties(names, params, fields, getters, constructorParams, builderParams);
        }

        private void stripBeans(List<Property.Getter> getters) {
            if (getters.stream().allMatch(Property.Getter::isBean)) {
                for (Property.Getter getter : getters) {
                    getter.stripBean();
                }
            }
        }

        private void removeExtraBuilders() {
            for (int i = builderParams.size() - 1; i >= 0; i--) {
                Property.BuilderParam builderParam = builderParams.get(i);
                if (containsName(constructorParams, builderParam)) {
                    builderParams.remove(i);
                    params.remove(builderParam);
                }
            }
        }

        private void removeExtraFields() {
            for (int i = fields.size() - 1; i >= 0; i--) {
                Property.Field field = fields.get(i);
                Set<Modifier> modifiers = field.element.getModifiers();
                if (modifiers.contains(Modifier.PRIVATE)
                        || modifiers.contains(Modifier.TRANSIENT)
                        || containsName(getters, field)) {
                    fields.remove(i);
                }
            }
        }

        private void removeGettersForTransientFields() {
            for (int i = getters.size() - 1; i >= 0; i--) {
                Property.Getter getter = getters.get(i);
                Property<?> field = findName(fields, getter);
                if (field != null && field.element.getModifiers().contains(Modifier.TRANSIENT)) {
                    getters.remove(i);
                }
            }
        }

        private boolean isMethodToSkip(TypeElement classElement, ExecutableElement method) {
            String name = method.getSimpleName().toString();
            if (METHODS_TO_SKIP.contains(name)) {
                return true;
            }
            return isKotlinClass(classElement) && name.matches("component[0-9]+");
        }
    }

    private static void merge(Property<?>[] properties) throws ElementException {
        if (properties.length == 0) return;
        List<AnnotationMirror> annotations = null;
        for (Property<?> name : properties) {
            if (name == null) continue;
            if (!name.getAnnotations().isEmpty()) {
                if (annotations == null) annotations = new ArrayList<>(name.getAnnotations());
                else {
                    for (AnnotationMirror annotation : name.getAnnotations()) {
                        if (annotations.contains(annotation)) {
                            throw new ElementException("Duplicate annotation " + annotation + " found on " + name, name.element);
                        } else annotations.add(annotation);
                    }
                }
            }
        }
        if (annotations != null) {
            for (Property<?> name : properties) {
                if (name == null) continue;
                name.setAnnotations(annotations);
            }
        }
    }

    @SafeVarargs
    private static void mergeSerializeNames(List<? extends Property<?>>... propertyLists) throws ElementException {
        if (propertyLists.length == 0) return;
        for (Property<?> name : propertyLists[0]) {
            var names = new Property<?>[propertyLists.length];
            names[0] = name;
            for (int i = 1; i < propertyLists.length; i++) {
                names[i] = findName(propertyLists[i], name);
            }
            merge(names);
        }
    }

    private static <N extends Property<?>> N findName(List<N> names, Property<?> property) {
        return names.stream().filter(n -> n.getName().equals(property.getName())).findFirst().orElse(null);
    }

    private static boolean containsName(List<? extends Property<?>> properties, Property<?> property) {
        return findName(properties, property) != null;
    }

    private static boolean isKotlinClass(TypeElement element) {
        return element.getAnnotationMirrors().stream().anyMatch(m -> m.getAnnotationType().toString().equals("kotlin.Metadata"));
    }
}