/*
 * Copyright 2020 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 androidx.car.app.model;

import static androidx.car.app.model.constraints.ActionsConstraints.ACTIONS_CONSTRAINTS_BODY_WITH_PRIMARY_ACTION;
import static androidx.car.app.model.constraints.ActionsConstraints.ACTIONS_CONSTRAINTS_HEADER;
import static androidx.car.app.model.constraints.ActionsConstraints.ACTIONS_CONSTRAINTS_SIMPLE;
import static androidx.car.app.model.constraints.RowListConstraints.ROW_LIST_CONSTRAINTS_PANE;

import static java.util.Objects.requireNonNull;

import androidx.annotation.Keep;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.car.app.annotations.CarProtocol;
import androidx.car.app.model.constraints.CarTextConstraints;

import java.util.Collections;
import java.util.Objects;

/**
 * A template that displays a {@link Pane}.
 *
 * <h4>Template Restrictions</h4>
 *
 * In regards to template refreshes, as described in
 * {@link androidx.car.app.Screen#onGetTemplate()}, this template is considered a refresh of a
 * previous one if:
 *
 * <ul>
 *   <li>The previous template is in a loading state (see {@link Pane.Builder#setLoading}, or
 *   <li>The template title has not changed, and the number of rows and the title (not counting
 *       spans) of each row between the previous and new {@link Pane}s have not changed.
 * </ul>
 */
@CarProtocol
public final class PaneTemplate implements Template {
    @Keep
    @Nullable
    private final CarText mTitle;
    @Keep
    @Nullable
    private final Pane mPane;
    @Keep
    @Nullable
    private final Action mHeaderAction;
    @Keep
    @Nullable
    private final ActionStrip mActionStrip;

    /**
     * Returns the title of the template or {@code null} if not set.
     *
     * @see Builder#setTitle(CharSequence)
     */
    @Nullable
    public CarText getTitle() {
        return mTitle;
    }

    /**
     * Returns the {@link Action} that is set to be displayed in the header of the template, or
     * {@code null} if not set.
     *
     * @see Builder#setHeaderAction(Action)
     */
    @Nullable
    public Action getHeaderAction() {
        return mHeaderAction;
    }

    /**
     * Returns the {@link ActionStrip} for this template or {@code null} if not set.
     *
     * @see Builder#setActionStrip(ActionStrip)
     */
    @Nullable
    public ActionStrip getActionStrip() {
        return mActionStrip;
    }

    /**
     * Returns the {@link Pane} to display in the template.
     *
     * @see Builder#Builder(Pane)
     */
    @NonNull
    public Pane getPane() {
        return requireNonNull(mPane);
    }

    @NonNull
    @Override
    public String toString() {
        return "PaneTemplate";
    }

    @Override
    public int hashCode() {
        return Objects.hash(mTitle, mPane, mHeaderAction, mActionStrip);
    }

    @Override
    public boolean equals(@Nullable Object other) {
        if (this == other) {
            return true;
        }
        if (!(other instanceof PaneTemplate)) {
            return false;
        }
        PaneTemplate otherTemplate = (PaneTemplate) other;

        return Objects.equals(mTitle, otherTemplate.mTitle)
                && Objects.equals(mPane, otherTemplate.mPane)
                && Objects.equals(mHeaderAction, otherTemplate.mHeaderAction)
                && Objects.equals(mActionStrip, otherTemplate.mActionStrip);
    }

    PaneTemplate(Builder builder) {
        mTitle = builder.mTitle;
        mPane = builder.mPane;
        mHeaderAction = builder.mHeaderAction;
        mActionStrip = builder.mActionStrip;
    }

    /** Constructs an empty instance, used by serialization code. */
    private PaneTemplate() {
        mTitle = null;
        mPane = null;
        mHeaderAction = null;
        mActionStrip = null;
    }

    /** A builder of {@link PaneTemplate}. */
    public static final class Builder {
        @Nullable
        CarText mTitle;
        Pane mPane;
        @Nullable
        Action mHeaderAction;
        @Nullable
        ActionStrip mActionStrip;

        /**
         * Sets the title of the template.
         *
         * <p>Unless set with this method, the template will not have a title.
         *
         * <p>Only {@link DistanceSpan}s and {@link DurationSpan}s are supported in the input
         * string.
         *
         * @throws NullPointerException     if {@code title} is {@code null}
         * @throws IllegalArgumentException if {@code title} contains unsupported spans
         * @see CarText
         */
        @NonNull
        public Builder setTitle(@NonNull CharSequence title) {
            mTitle = CarText.create(requireNonNull(title));
            CarTextConstraints.TEXT_ONLY.validateOrThrow(mTitle);
            return this;
        }

        /**
         * Sets the {@link Action} that will be displayed in the header of the template.
         *
         * <p>Unless set with this method, the template will not have a header action.
         *
         * <h4>Requirements</h4>
         *
         * This template only supports either one of {@link Action#APP_ICON} and
         * {@link Action#BACK} as a header {@link Action}.
         *
         * @throws IllegalArgumentException if {@code headerAction} does not meet the template's
         *                                  requirements
         * @throws NullPointerException     if {@code headerAction} is {@code null}
         */
        @NonNull
        public Builder setHeaderAction(@NonNull Action headerAction) {
            ACTIONS_CONSTRAINTS_HEADER.validateOrThrow(
                    Collections.singletonList(requireNonNull(headerAction)));
            mHeaderAction = headerAction;
            return this;
        }

        /**
         * Sets the {@link ActionStrip} for this template.
         *
         * <p>Unless set with this method, the template will not have an action strip.
         *
         * <h4>Requirements</h4>
         *
         * This template allows up to 2 {@link Action}s in its {@link ActionStrip}. Of the 2 allowed
         * {@link Action}s, one of them can contain a title as set via
         * {@link Action.Builder#setTitle}. Otherwise, only {@link Action}s with icons are allowed.
         *
         * @throws IllegalArgumentException if {@code actionStrip} does not meet the requirements
         * @throws NullPointerException     if {@code actionStrip} is {@code null}
         */
        @NonNull
        public Builder setActionStrip(@NonNull ActionStrip actionStrip) {
            ACTIONS_CONSTRAINTS_SIMPLE.validateOrThrow(requireNonNull(actionStrip).getActions());
            mActionStrip = actionStrip;
            return this;
        }

        /**
         * Constructs the template defined by this builder.
         *
         * <h4>Requirements</h4>
         *
         * The number of items in the {@link ItemList} should be smaller or equal than the limit
         * provided by
         * {@link androidx.car.app.constraints.ConstraintManager#CONTENT_LIMIT_TYPE_PANE}. The host
         * will ignore any rows over that limit. Each {@link Row}s can add up to 2 lines of texts
         * via {@link Row.Builder#addText} and cannot contain either a {@link Toggle} or a {@link
         * OnClickListener}.
         *
         * <p>Up to 2 {@link Action}s are allowed in the {@link Pane}. Each action's title color
         * can be customized with {@link ForegroundCarColorSpan} instances. Any other span is not
         * supported.
         *
         * <p>Either a header {@link Action} or title must be set on the template.
         *
         * @throws IllegalArgumentException if the {@link Pane} does not meet the requirements
         * @throws IllegalStateException    if the template does not have either a title or header
         *                                  {@link Action} set
         * @see androidx.car.app.constraints.ConstraintManager#getContentLimit(int)
         */
        @NonNull
        public PaneTemplate build() {
            ROW_LIST_CONSTRAINTS_PANE.validateOrThrow(mPane);
            ACTIONS_CONSTRAINTS_BODY_WITH_PRIMARY_ACTION.validateOrThrow(mPane.getActions());

            if (CarText.isNullOrEmpty(mTitle) && mHeaderAction == null) {
                throw new IllegalStateException("Either the title or header action must be set");
            }

            return new PaneTemplate(this);
        }

        /**
         * Returns a new instance of a @link Builder}.
         *
         * @throws NullPointerException if {@code pane} is {@code null}
         */
        public Builder(@NonNull Pane pane) {
            mPane = pane;
        }
    }
}