/*
 * Copyright 2002-2018 the original author or authors.
 *
 * 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
 *
 *      https://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 org.springframework.web.reactive.result.view;

import java.beans.PropertyEditor;
import java.util.Arrays;
import java.util.List;

import org.springframework.beans.BeanWrapper;
import org.springframework.beans.PropertyAccessorFactory;
import org.springframework.context.NoSuchMessageException;
import org.springframework.lang.Nullable;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;
import org.springframework.validation.BindingResult;
import org.springframework.validation.Errors;
import org.springframework.validation.ObjectError;
import org.springframework.web.util.HtmlUtils;

/**
 * Simple adapter to expose the bind status of a field or object.
 * Set as a variable by FreeMarker macros and other tag libraries.
 *
 * <p>Obviously, object status representations (i.e. errors at the object level
 * rather than the field level) do not have an expression and a value but only
 * error codes and messages. For simplicity's sake and to be able to use the same
 * tags and macros, the same status class is used for both scenarios.
 *
 * @author Rossen Stoyanchev
 * @author Juergen Hoeller
 * @since 5.0
 * @see RequestContext#getBindStatus
 */
public class BindStatus {

        private final RequestContext requestContext;

        private final String path;

        private final boolean htmlEscape;

        @Nullable
        private final String expression;

        @Nullable
        private final Errors errors;

        private final String[] errorCodes;

        @Nullable
        private String[] errorMessages;

        @Nullable
        private List<? extends ObjectError> objectErrors;

        @Nullable
        private Object value;

        @Nullable
        private Class<?> valueType;

        @Nullable
        private Object actualValue;

        @Nullable
        private PropertyEditor editor;

        @Nullable
        private BindingResult bindingResult;


        /**
         * Create a new BindStatus instance, representing a field or object status.
         * @param requestContext the current RequestContext
         * @param path the bean and property path for which values and errors
         * will be resolved (e.g. "customer.address.street")
         * @param htmlEscape whether to HTML-escape error messages and string values
         * @throws IllegalStateException if no corresponding Errors object found
         */
        public BindStatus(RequestContext requestContext, String path, boolean htmlEscape) throws IllegalStateException {
                this.requestContext = requestContext;
                this.path = path;
                this.htmlEscape = htmlEscape;

                // determine name of the object and property
                String beanName;
                int dotPos = path.indexOf('.');
                if (dotPos == -1) {
                        // property not set, only the object itself
                        beanName = path;
                        this.expression = null;
                }
                else {
                        beanName = path.substring(0, dotPos);
                        this.expression = path.substring(dotPos + 1);
                }

                this.errors = requestContext.getErrors(beanName, false);

                if (this.errors != null) {
                        // Usual case: A BindingResult is available as request attribute.
                        // Can determine error codes and messages for the given expression.
                        // Can use a custom PropertyEditor, as registered by a form controller.
                        if (this.expression != null) {
                                if ("*".equals(this.expression)) {
                                        this.objectErrors = this.errors.getAllErrors();
                                }
                                else if (this.expression.endsWith("*")) {
                                        this.objectErrors = this.errors.getFieldErrors(this.expression);
                                }
                                else {
                                        this.objectErrors = this.errors.getFieldErrors(this.expression);
                                        this.value = this.errors.getFieldValue(this.expression);
                                        this.valueType = this.errors.getFieldType(this.expression);
                                        if (this.errors instanceof BindingResult) {
                                                this.bindingResult = (BindingResult) this.errors;
                                                this.actualValue = this.bindingResult.getRawFieldValue(this.expression);
                                                this.editor = this.bindingResult.findEditor(this.expression, null);
                                        }
                                        else {
                                                this.actualValue = this.value;
                                        }
                                }
                        }
                        else {
                                this.objectErrors = this.errors.getGlobalErrors();
                        }
                        this.errorCodes = initErrorCodes(this.objectErrors);
                }

                else {
                        // No BindingResult available as request attribute:
                        // Probably forwarded directly to a form view.
                        // Let's do the best we can: extract a plain target if appropriate.
                        Object target = requestContext.getModelObject(beanName);
                        if (target == null) {
                                throw new IllegalStateException(
                                                "Neither BindingResult nor plain target object for bean name '" +
                                                beanName + "' available as request attribute");
                        }
                        if (this.expression != null && !"*".equals(this.expression) && !this.expression.endsWith("*")) {
                                BeanWrapper bw = PropertyAccessorFactory.forBeanPropertyAccess(target);
                                this.value = bw.getPropertyValue(this.expression);
                                this.valueType = bw.getPropertyType(this.expression);
                                this.actualValue = this.value;
                        }
                        this.errorCodes = new String[0];
                        this.errorMessages = new String[0];
                }

                if (htmlEscape && this.value instanceof String) {
                        this.value = HtmlUtils.htmlEscape((String) this.value);
                }
        }

        /**
         * Extract the error codes from the ObjectError list.
         */
        private static String[] initErrorCodes(List<? extends ObjectError> objectErrors) {
                String[] errorCodes = new String[objectErrors.size()];
                for (int i = 0; i < objectErrors.size(); i++) {
                        ObjectError error = objectErrors.get(i);
                        errorCodes[i] = error.getCode();
                }
                return errorCodes;
        }


        /**
         * Return the bean and property path for which values and errors
         * will be resolved (e.g. "customer.address.street").
         */
        public String getPath() {
                return this.path;
        }

        /**
         * Return a bind expression that can be used in HTML forms as input name
         * for the respective field, or {@code null} if not field-specific.
         * <p>Returns a bind path appropriate for resubmission, e.g. "address.street".
         * Note that the complete bind path as required by the bind tag is
         * "customer.address.street", if bound to a "customer" bean.
         */
        @Nullable
        public String getExpression() {
                return this.expression;
        }

        /**
         * Return the current value of the field, i.e. either the property value
         * or a rejected update, or {@code null} if not field-specific.
         * <p>This value will be an HTML-escaped String if the original value
         * already was a String.
         */
        @Nullable
        public Object getValue() {
                return this.value;
        }

        /**
         * Get the '{@code Class}' type of the field. Favor this instead of
         * '{@code getValue().getClass()}' since '{@code getValue()}' may
         * return '{@code null}'.
         */
        @Nullable
        public Class<?> getValueType() {
                return this.valueType;
        }

        /**
         * Return the actual value of the field, i.e. the raw property value,
         * or {@code null} if not available.
         */
        @Nullable
        public Object getActualValue() {
                return this.actualValue;
        }

        /**
         * Return a suitable display value for the field, i.e. the stringified
         * value if not null, and an empty string in case of a null value.
         * <p>This value will be an HTML-escaped String if the original value
         * was non-null: the {@code toString} result of the original value
         * will get HTML-escaped.
         */
        public String getDisplayValue() {
                if (this.value instanceof String) {
                        return (String) this.value;
                }
                if (this.value != null) {
                        return (this.htmlEscape ?
                                        HtmlUtils.htmlEscape(this.value.toString()) : this.value.toString());
                }
                return "";
        }

        /**
         * Return if this status represents a field or object error.
         */
        public boolean isError() {
                return (this.errorCodes.length > 0);
        }

        /**
         * Return the error codes for the field or object, if any.
         * Returns an empty array instead of null if none.
         */
        public String[] getErrorCodes() {
                return this.errorCodes;
        }

        /**
         * Return the first error codes for the field or object, if any.
         */
        public String getErrorCode() {
                return (!ObjectUtils.isEmpty(this.errorCodes) ? this.errorCodes[0] : "");
        }

        /**
         * Return the resolved error messages for the field or object,
         * if any. Returns an empty array instead of null if none.
         */
        public String[] getErrorMessages() {
                return initErrorMessages();
        }

        /**
         * Return the first error message for the field or object, if any.
         */
        public String getErrorMessage() {
                String[] errorMessages = initErrorMessages();
                return (errorMessages.length > 0 ? errorMessages[0] : "");
        }

        /**
         * Return an error message string, concatenating all messages
         * separated by the given delimiter.
         * @param delimiter separator string, e.g. ", " or "<br>"
         * @return the error message string
         */
        public String getErrorMessagesAsString(String delimiter) {
                return StringUtils.arrayToDelimitedString(initErrorMessages(), delimiter);
        }

        /**
         * Extract the error messages from the ObjectError list.
         */
        private String[] initErrorMessages() throws NoSuchMessageException {
                if (this.errorMessages == null) {
                        if (this.objectErrors != null) {
                                this.errorMessages = new String[this.objectErrors.size()];
                                for (int i = 0; i < this.objectErrors.size(); i++) {
                                        ObjectError error = this.objectErrors.get(i);
                                        this.errorMessages[i] = this.requestContext.getMessage(error, this.htmlEscape);
                                }
                        }
                        else {
                                this.errorMessages = new String[0];
                        }
                }
                return this.errorMessages;
        }

        /**
         * Return the Errors instance (typically a BindingResult) that this
         * bind status is currently associated with.
         * @return the current Errors instance, or {@code null} if none
         * @see org.springframework.validation.BindingResult
         */
        @Nullable
        public Errors getErrors() {
                return this.errors;
        }

        /**
         * Return the PropertyEditor for the property that this bind status
         * is currently bound to.
         * @return the current PropertyEditor, or {@code null} if none
         */
        @Nullable
        public PropertyEditor getEditor() {
                return this.editor;
        }

        /**
         * Find a PropertyEditor for the given value class, associated with
         * the property that this bound status is currently bound to.
         * @param valueClass the value class that an editor is needed for
         * @return the associated PropertyEditor, or {@code null} if none
         */
        @Nullable
        public PropertyEditor findEditor(Class<?> valueClass) {
                return (this.bindingResult != null ?
                                this.bindingResult.findEditor(this.expression, valueClass) : null);
        }


        @Override
        public String toString() {
                StringBuilder sb = new StringBuilder("BindStatus: ");
                sb.append("expression=[").append(this.expression).append("]; ");
                sb.append("value=[").append(this.value).append("]");
                if (!ObjectUtils.isEmpty(this.errorCodes)) {
                        sb.append("; errorCodes=").append(Arrays.asList(this.errorCodes));
                }
                return sb.toString();
        }

}