package org.zwobble.mammoth.internal.docx;

import org.zwobble.mammoth.internal.documents.DocumentElement;
import org.zwobble.mammoth.internal.results.InternalResult;

import java.util.List;
import java.util.function.BiFunction;
import java.util.function.Function;

import static org.zwobble.mammoth.internal.util.Iterables.lazyConcat;
import static org.zwobble.mammoth.internal.util.Iterables.lazyFlatMap;
import static org.zwobble.mammoth.internal.util.Lists.*;

public class ReadResult {
    public static final ReadResult EMPTY_SUCCESS = success(list());

    public static <T> ReadResult flatMap(Iterable<T> iterable, Function<T, ReadResult> function) {
        List<ReadResult> results = eagerMap(iterable, function);
        return new ReadResult(
            eagerFlatMap(results, result -> result.elements),
            eagerFlatMap(results, result -> result.extra),
            lazyFlatMap(results, result -> result.warnings));
    }

    public static <T> ReadResult map(
        InternalResult<T> first,
        ReadResult second,
        BiFunction<T, List<DocumentElement>, DocumentElement> function)
    {
        return new ReadResult(
            list(function.apply(first.getValue(), second.elements)),
            second.extra,
            lazyConcat(first.getWarnings(), second.warnings));
    }

    public static ReadResult success(DocumentElement element) {
        return success(list(element));
    }

    public static ReadResult success(List<DocumentElement> elements) {
        return new ReadResult(elements, list(), list());
    }

    public static ReadResult emptyWithWarning(String warning) {
        return withWarning(list(), warning);
    }

    public static ReadResult withWarning(DocumentElement element, String warning) {
        return withWarning(list(element), warning);
    }

    public static ReadResult withWarning(List<DocumentElement> elements, String warning) {
        return new ReadResult(elements, list(), list(warning));
    }

    private final List<DocumentElement> elements;
    private final List<DocumentElement> extra;
    private final Iterable<String> warnings;

    public ReadResult(List<DocumentElement> elements, List<DocumentElement> extra, Iterable<String> warnings) {
        this.elements = elements;
        this.extra = extra;
        this.warnings = warnings;
    }

    public ReadResult map(Function<List<DocumentElement>, List<DocumentElement>> function) {
        return new ReadResult(
            function.apply(elements),
            extra,
            warnings);
    }

    public ReadResult flatMap(Function<List<DocumentElement>, ReadResult> function) {
        ReadResult result = function.apply(elements);
        return new ReadResult(
            result.elements,
            eagerConcat(extra, result.extra),
            lazyConcat(warnings, result.warnings));
    }

    public ReadResult toExtra() {
        return new ReadResult(list(), eagerConcat(extra, elements), warnings);
    }

    public ReadResult appendExtra() {
        return new ReadResult(eagerConcat(elements, extra), list(), warnings);
    }

    public InternalResult<List<DocumentElement>> toResult() {
        return new InternalResult<>(elements, warnings);
    }
}