/*
 * Copyright 2017 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.view.textclassifier;

import android.annotation.FloatRange;
import android.annotation.IntDef;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.content.Context;
import android.os.LocaleList;
import android.os.Parcel;
import android.os.Parcelable;
import android.text.Spannable;
import android.text.method.MovementMethod;
import android.text.style.ClickableSpan;
import android.text.style.URLSpan;
import android.text.util.Linkify;
import android.text.util.Linkify.LinkifyMask;
import android.view.View;
import android.view.textclassifier.TextClassifier.EntityType;
import android.widget.TextView;

import com.android.internal.annotations.VisibleForTesting;
import com.android.internal.annotations.VisibleForTesting.Visibility;
import com.android.internal.util.Preconditions;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.function.Function;

/**
 * A collection of links, representing subsequences of text and the entity types (phone number,
 * address, url, etc) they may be.
 */
public final class TextLinks implements Parcelable {

    /**
     * Return status of an attempt to apply TextLinks to text.
     * @hide
     */
    @Retention(RetentionPolicy.SOURCE)
    @IntDef({STATUS_LINKS_APPLIED, STATUS_NO_LINKS_FOUND, STATUS_NO_LINKS_APPLIED,
            STATUS_DIFFERENT_TEXT})
    public @interface Status {}

    /** Links were successfully applied to the text. */
    public static final int STATUS_LINKS_APPLIED = 0;

    /** No links exist to apply to text. Links count is zero. */
    public static final int STATUS_NO_LINKS_FOUND = 1;

    /** No links applied to text. The links were filtered out. */
    public static final int STATUS_NO_LINKS_APPLIED = 2;

    /** The specified text does not match the text used to generate the links. */
    public static final int STATUS_DIFFERENT_TEXT = 3;

    /** @hide */
    @Retention(RetentionPolicy.SOURCE)
    @IntDef({APPLY_STRATEGY_IGNORE, APPLY_STRATEGY_REPLACE})
    public @interface ApplyStrategy {}

    /**
     * Do not replace {@link ClickableSpan}s that exist where the {@link TextLinkSpan} needs to
     * be applied to. Do not apply the TextLinkSpan.
     */
    public static final int APPLY_STRATEGY_IGNORE = 0;

    /**
     * Replace any {@link ClickableSpan}s that exist where the {@link TextLinkSpan} needs to be
     * applied to.
     */
    public static final int APPLY_STRATEGY_REPLACE = 1;

    private final String mFullText;
    private final List<TextLink> mLinks;

    private TextLinks(String fullText, ArrayList<TextLink> links) {
        mFullText = fullText;
        mLinks = Collections.unmodifiableList(links);
    }

    /**
     * Returns the text that was used to generate these links.
     * @hide
     */
    @NonNull
    public String getText() {
        return mFullText;
    }

    /**
     * Returns an unmodifiable Collection of the links.
     */
    @NonNull
    public Collection<TextLink> getLinks() {
        return mLinks;
    }

    /**
     * Annotates the given text with the generated links. It will fail if the provided text doesn't
     * match the original text used to create the TextLinks.
     *
     * <p><strong>NOTE: </strong>It may be necessary to set a LinkMovementMethod on the TextView
     * widget to properly handle links. See {@link TextView#setMovementMethod(MovementMethod)}
     *
     * @param text the text to apply the links to. Must match the original text
     * @param applyStrategy the apply strategy used to determine how to apply links to text.
     *      e.g {@link TextLinks#APPLY_STRATEGY_IGNORE}
     * @param spanFactory a custom span factory for converting TextLinks to TextLinkSpans.
     *      Set to {@code null} to use the default span factory.
     *
     * @return a status code indicating whether or not the links were successfully applied
     *      e.g. {@link #STATUS_LINKS_APPLIED}
     */
    @Status
    public int apply(
            @NonNull Spannable text,
            @ApplyStrategy int applyStrategy,
            @Nullable Function<TextLink, TextLinkSpan> spanFactory) {
        Preconditions.checkNotNull(text);
        return new TextLinksParams.Builder()
                .setApplyStrategy(applyStrategy)
                .setSpanFactory(spanFactory)
                .build()
                .apply(text, this);
    }

    @Override
    public String toString() {
        return String.format(Locale.US, "TextLinks{fullText=%s, links=%s}", mFullText, mLinks);
    }

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeString(mFullText);
        dest.writeTypedList(mLinks);
    }

    public static final Parcelable.Creator<TextLinks> CREATOR =
            new Parcelable.Creator<TextLinks>() {
                @Override
                public TextLinks createFromParcel(Parcel in) {
                    return new TextLinks(in);
                }

                @Override
                public TextLinks[] newArray(int size) {
                    return new TextLinks[size];
                }
            };

    private TextLinks(Parcel in) {
        mFullText = in.readString();
        mLinks = in.createTypedArrayList(TextLink.CREATOR);
    }

    /**
     * A link, identifying a substring of text and possible entity types for it.
     */
    public static final class TextLink implements Parcelable {
        private final EntityConfidence mEntityScores;
        private final int mStart;
        private final int mEnd;
        @Nullable final URLSpan mUrlSpan;

        /**
         * Create a new TextLink.
         *
         * @param start The start index of the identified subsequence
         * @param end The end index of the identified subsequence
         * @param entityScores A mapping of entity type to confidence score
         * @param urlSpan An optional URLSpan to delegate to. NOTE: Not parcelled
         *
         * @throws IllegalArgumentException if entityScores is null or empty
         */
        TextLink(int start, int end, Map<String, Float> entityScores,
                @Nullable URLSpan urlSpan) {
            Preconditions.checkNotNull(entityScores);
            Preconditions.checkArgument(!entityScores.isEmpty());
            Preconditions.checkArgument(start <= end);
            mStart = start;
            mEnd = end;
            mEntityScores = new EntityConfidence(entityScores);
            mUrlSpan = urlSpan;
        }

        /**
         * Returns the start index of this link in the original text.
         *
         * @return the start index
         */
        public int getStart() {
            return mStart;
        }

        /**
         * Returns the end index of this link in the original text.
         *
         * @return the end index
         */
        public int getEnd() {
            return mEnd;
        }

        /**
         * Returns the number of entity types that have confidence scores.
         *
         * @return the entity count
         */
        public int getEntityCount() {
            return mEntityScores.getEntities().size();
        }

        /**
         * Returns the entity type at a given index. Entity types are sorted by confidence.
         *
         * @return the entity type at the provided index
         */
        @NonNull public @EntityType String getEntity(int index) {
            return mEntityScores.getEntities().get(index);
        }

        /**
         * Returns the confidence score for a particular entity type.
         *
         * @param entityType the entity type
         */
        public @FloatRange(from = 0.0, to = 1.0) float getConfidenceScore(
                @EntityType String entityType) {
            return mEntityScores.getConfidenceScore(entityType);
        }

        @Override
        public String toString() {
            return String.format(Locale.US,
                    "TextLink{start=%s, end=%s, entityScores=%s, urlSpan=%s}",
                    mStart, mEnd, mEntityScores, mUrlSpan);
        }

        @Override
        public int describeContents() {
            return 0;
        }

        @Override
        public void writeToParcel(Parcel dest, int flags) {
            mEntityScores.writeToParcel(dest, flags);
            dest.writeInt(mStart);
            dest.writeInt(mEnd);
        }

        public static final Parcelable.Creator<TextLink> CREATOR =
                new Parcelable.Creator<TextLink>() {
                    @Override
                    public TextLink createFromParcel(Parcel in) {
                        return new TextLink(in);
                    }

                    @Override
                    public TextLink[] newArray(int size) {
                        return new TextLink[size];
                    }
                };

        private TextLink(Parcel in) {
            mEntityScores = EntityConfidence.CREATOR.createFromParcel(in);
            mStart = in.readInt();
            mEnd = in.readInt();
            mUrlSpan = null;
        }
    }

    /**
     * A request object for generating TextLinks.
     */
    public static final class Request implements Parcelable {

        private final CharSequence mText;
        @Nullable private final LocaleList mDefaultLocales;
        @Nullable private final TextClassifier.EntityConfig mEntityConfig;
        private final boolean mLegacyFallback;
        private String mCallingPackageName;

        private Request(
                CharSequence text,
                LocaleList defaultLocales,
                TextClassifier.EntityConfig entityConfig,
                boolean legacyFallback,
                String callingPackageName) {
            mText = text;
            mDefaultLocales = defaultLocales;
            mEntityConfig = entityConfig;
            mLegacyFallback = legacyFallback;
            mCallingPackageName = callingPackageName;
        }

        /**
         * Returns the text to generate links for.
         */
        @NonNull
        public CharSequence getText() {
            return mText;
        }

        /**
         * @return ordered list of locale preferences that can be used to disambiguate
         *      the provided text
         */
        @Nullable
        public LocaleList getDefaultLocales() {
            return mDefaultLocales;
        }

        /**
         * @return The config representing the set of entities to look for
         * @see Builder#setEntityConfig(TextClassifier.EntityConfig)
         */
        @Nullable
        public TextClassifier.EntityConfig getEntityConfig() {
            return mEntityConfig;
        }

        /**
         * Returns whether the TextClassifier can fallback to legacy links if smart linkify is
         * disabled.
         * <strong>Note: </strong>This is not parcelled.
         * @hide
         */
        public boolean isLegacyFallback() {
            return mLegacyFallback;
        }

        /**
         * Sets the name of the package that requested the links to get generated.
         */
        void setCallingPackageName(@Nullable String callingPackageName) {
            mCallingPackageName = callingPackageName;
        }

        /**
         * A builder for building TextLinks requests.
         */
        public static final class Builder {

            private final CharSequence mText;

            @Nullable private LocaleList mDefaultLocales;
            @Nullable private TextClassifier.EntityConfig mEntityConfig;
            private boolean mLegacyFallback = true; // Use legacy fall back by default.
            private String mCallingPackageName;

            public Builder(@NonNull CharSequence text) {
                mText = Preconditions.checkNotNull(text);
            }

            /**
             * @param defaultLocales ordered list of locale preferences that may be used to
             *                       disambiguate the provided text. If no locale preferences exist,
             *                       set this to null or an empty locale list.
             * @return this builder
             */
            @NonNull
            public Builder setDefaultLocales(@Nullable LocaleList defaultLocales) {
                mDefaultLocales = defaultLocales;
                return this;
            }

            /**
             * Sets the entity configuration to use. This determines what types of entities the
             * TextClassifier will look for.
             * Set to {@code null} for the default entity config and teh TextClassifier will
             * automatically determine what links to generate.
             *
             * @return this builder
             */
            @NonNull
            public Builder setEntityConfig(@Nullable TextClassifier.EntityConfig entityConfig) {
                mEntityConfig = entityConfig;
                return this;
            }

            /**
             * Sets whether the TextClassifier can fallback to legacy links if smart linkify is
             * disabled.
             *
             * <p><strong>Note: </strong>This is not parcelled.
             *
             * @return this builder
             * @hide
             */
            @NonNull
            public Builder setLegacyFallback(boolean legacyFallback) {
                mLegacyFallback = legacyFallback;
                return this;
            }

            /**
             * Sets the name of the package that requested the links to get generated.
             *
             * @return this builder
             * @hide
             */
            @NonNull
            public Builder setCallingPackageName(@Nullable String callingPackageName) {
                mCallingPackageName = callingPackageName;
                return this;
            }

            /**
             * Builds and returns the request object.
             */
            @NonNull
            public Request build() {
                return new Request(
                        mText, mDefaultLocales, mEntityConfig,
                        mLegacyFallback, mCallingPackageName);
            }

        }

        /**
         * @return the name of the package that requested the links to get generated.
         * TODO: make available as system API
         * @hide
         */
        @Nullable
        public String getCallingPackageName() {
            return mCallingPackageName;
        }

        @Override
        public int describeContents() {
            return 0;
        }

        @Override
        public void writeToParcel(Parcel dest, int flags) {
            dest.writeString(mText.toString());
            dest.writeInt(mDefaultLocales != null ? 1 : 0);
            if (mDefaultLocales != null) {
                mDefaultLocales.writeToParcel(dest, flags);
            }
            dest.writeInt(mEntityConfig != null ? 1 : 0);
            if (mEntityConfig != null) {
                mEntityConfig.writeToParcel(dest, flags);
            }
            dest.writeString(mCallingPackageName);
        }

        public static final Parcelable.Creator<Request> CREATOR =
                new Parcelable.Creator<Request>() {
                    @Override
                    public Request createFromParcel(Parcel in) {
                        return new Request(in);
                    }

                    @Override
                    public Request[] newArray(int size) {
                        return new Request[size];
                    }
                };

        private Request(Parcel in) {
            mText = in.readString();
            mDefaultLocales = in.readInt() == 0 ? null : LocaleList.CREATOR.createFromParcel(in);
            mEntityConfig = in.readInt() == 0
                    ? null : TextClassifier.EntityConfig.CREATOR.createFromParcel(in);
            mLegacyFallback = true;
            mCallingPackageName = in.readString();
        }
    }

    /**
     * A ClickableSpan for a TextLink.
     *
     * <p>Applies only to TextViews.
     */
    public static class TextLinkSpan extends ClickableSpan {

        private final TextLink mTextLink;

        public TextLinkSpan(@NonNull TextLink textLink) {
            mTextLink = textLink;
        }

        @Override
        public void onClick(View widget) {
            if (widget instanceof TextView) {
                final TextView textView = (TextView) widget;
                final Context context = textView.getContext();
                if (TextClassificationManager.getSettings(context).isSmartLinkifyEnabled()) {
                    if (textView.requestFocus()) {
                        textView.requestActionMode(this);
                    } else {
                        // If textView can not take focus, then simply handle the click as it will
                        // be difficult to get rid of the floating action mode.
                        textView.handleClick(this);
                    }
                } else {
                    if (mTextLink.mUrlSpan != null) {
                        mTextLink.mUrlSpan.onClick(textView);
                    } else {
                        textView.handleClick(this);
                    }
                }
            }
        }

        public final TextLink getTextLink() {
            return mTextLink;
        }

        /** @hide */
        @VisibleForTesting(visibility = Visibility.PRIVATE)
        @Nullable
        public final String getUrl() {
            if (mTextLink.mUrlSpan != null) {
                return mTextLink.mUrlSpan.getURL();
            }
            return null;
        }
    }

    /**
     * A builder to construct a TextLinks instance.
     */
    public static final class Builder {
        private final String mFullText;
        private final ArrayList<TextLink> mLinks;

        /**
         * Create a new TextLinks.Builder.
         *
         * @param fullText The full text to annotate with links
         */
        public Builder(@NonNull String fullText) {
            mFullText = Preconditions.checkNotNull(fullText);
            mLinks = new ArrayList<>();
        }

        /**
         * Adds a TextLink.
         *
         * @param start The start index of the identified subsequence
         * @param end The end index of the identified subsequence
         * @param entityScores A mapping of entity type to confidence score
         *
         * @throws IllegalArgumentException if entityScores is null or empty.
         */
        @NonNull
        public Builder addLink(int start, int end, Map<String, Float> entityScores) {
            mLinks.add(new TextLink(start, end, entityScores, null));
            return this;
        }

        /**
         * @see #addLink(int, int, Map)
         * @param urlSpan An optional URLSpan to delegate to. NOTE: Not parcelled.
         */
        @NonNull
        Builder addLink(int start, int end, Map<String, Float> entityScores,
                @Nullable URLSpan urlSpan) {
            mLinks.add(new TextLink(start, end, entityScores, urlSpan));
            return this;
        }

        /**
         * Removes all {@link TextLink}s.
         */
        @NonNull
        public Builder clearTextLinks() {
            mLinks.clear();
            return this;
        }

        /**
         * Constructs a TextLinks instance.
         *
         * @return the constructed TextLinks
         */
        @NonNull
        public TextLinks build() {
            return new TextLinks(mFullText, mLinks);
        }
    }

    // TODO: Remove once apps can build against the latest sdk.
    /**
     * Optional input parameters for generating TextLinks.
     * @hide
     */
    public static final class Options {

        @Nullable private final TextClassificationSessionId mSessionId;
        @Nullable private final Request mRequest;
        @Nullable private LocaleList mDefaultLocales;
        @Nullable private TextClassifier.EntityConfig mEntityConfig;
        private boolean mLegacyFallback;

        private @ApplyStrategy int mApplyStrategy;
        private Function<TextLink, TextLinkSpan> mSpanFactory;

        private String mCallingPackageName;

        public Options() {
            this(null, null);
        }

        private Options(
                @Nullable TextClassificationSessionId sessionId, @Nullable Request request) {
            mSessionId = sessionId;
            mRequest = request;
        }

        /** Helper to create Options from a Request. */
        public static Options from(TextClassificationSessionId sessionId, Request request) {
            final Options options = new Options(sessionId, request);
            options.setDefaultLocales(request.getDefaultLocales());
            options.setEntityConfig(request.getEntityConfig());
            return options;
        }

        /** Returns a new options object based on the specified link mask. */
        public static Options fromLinkMask(@LinkifyMask int mask) {
            final List<String> entitiesToFind = new ArrayList<>();

            if ((mask & Linkify.WEB_URLS) != 0) {
                entitiesToFind.add(TextClassifier.TYPE_URL);
            }
            if ((mask & Linkify.EMAIL_ADDRESSES) != 0) {
                entitiesToFind.add(TextClassifier.TYPE_EMAIL);
            }
            if ((mask & Linkify.PHONE_NUMBERS) != 0) {
                entitiesToFind.add(TextClassifier.TYPE_PHONE);
            }
            if ((mask & Linkify.MAP_ADDRESSES) != 0) {
                entitiesToFind.add(TextClassifier.TYPE_ADDRESS);
            }

            return new Options().setEntityConfig(
                    TextClassifier.EntityConfig.createWithEntityList(entitiesToFind));
        }

        /** @param defaultLocales ordered list of locale preferences. */
        public Options setDefaultLocales(@Nullable LocaleList defaultLocales) {
            mDefaultLocales = defaultLocales;
            return this;
        }

        /** @param entityConfig definition of which entity types to look for. */
        public Options setEntityConfig(@Nullable TextClassifier.EntityConfig entityConfig) {
            mEntityConfig = entityConfig;
            return this;
        }

        /** @param applyStrategy strategy to use when resolving conflicts. */
        public Options setApplyStrategy(@ApplyStrategy int applyStrategy) {
            checkValidApplyStrategy(applyStrategy);
            mApplyStrategy = applyStrategy;
            return this;
        }

        /** @param spanFactory factory for converting TextLink to TextLinkSpan. */
        public Options setSpanFactory(@Nullable Function<TextLink, TextLinkSpan> spanFactory) {
            mSpanFactory = spanFactory;
            return this;
        }

        @Nullable
        public LocaleList getDefaultLocales() {
            return mDefaultLocales;
        }

        @Nullable
        public TextClassifier.EntityConfig getEntityConfig() {
            return mEntityConfig;
        }

        @ApplyStrategy
        public int getApplyStrategy() {
            return mApplyStrategy;
        }

        @Nullable
        public Function<TextLink, TextLinkSpan> getSpanFactory() {
            return mSpanFactory;
        }

        @Nullable
        public Request getRequest() {
            return mRequest;
        }

        @Nullable
        public TextClassificationSessionId getSessionId() {
            return mSessionId;
        }

        private static void checkValidApplyStrategy(int applyStrategy) {
            if (applyStrategy != APPLY_STRATEGY_IGNORE && applyStrategy != APPLY_STRATEGY_REPLACE) {
                throw new IllegalArgumentException(
                        "Invalid apply strategy. See TextLinks.ApplyStrategy for options.");
            }
        }
    }
}