/*
 * Copyright 2002-2017 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
 *
 *      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 org.springframework.http;

import java.io.ByteArrayOutputStream;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.time.ZonedDateTime;
import java.time.format.DateTimeParseException;
import java.util.ArrayList;
import java.util.List;

import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ObjectUtils;

import static java.nio.charset.StandardCharsets.*;
import static java.time.format.DateTimeFormatter.*;

/**
 * Represent the Content-Disposition type and parameters as defined in RFC 2183.
 *
 * @author Sebastien Deleuze
 * @author Juergen Hoeller
 * @since 5.0
 * @see <a href="https://tools.ietf.org/html/rfc2183">RFC 2183</a>
 */
public class ContentDisposition {

	@Nullable
	private final String type;

	@Nullable
	private final String name;

	@Nullable
	private final String filename;

	@Nullable
	private final Charset charset;

	@Nullable
	private final Long size;

	@Nullable
	private final ZonedDateTime creationDate;

	@Nullable
	private final ZonedDateTime modificationDate;

	@Nullable
	private final ZonedDateTime readDate;


	/**
	 * Private constructor. See static factory methods in this class.
	 */
	private ContentDisposition(@Nullable String type, @Nullable String name, @Nullable String filename,
			@Nullable Charset charset, @Nullable Long size, @Nullable ZonedDateTime creationDate,
			@Nullable ZonedDateTime modificationDate, @Nullable ZonedDateTime readDate) {

		this.type = type;
		this.name = name;
		this.filename = filename;
		this.charset = charset;
		this.size = size;
		this.creationDate = creationDate;
		this.modificationDate = modificationDate;
		this.readDate = readDate;
	}


	/**
	 * Return the disposition type, like for example {@literal inline}, {@literal attachment},
	 * {@literal form-data}, or {@code null} if not defined.
	 */
	@Nullable
	public String getType() {
		return this.type;
	}

	/**
	 * Return the value of the {@literal name} parameter, or {@code null} if not defined.
	 */
	@Nullable
	public String getName() {
		return this.name;
	}

	/**
	 * Return the value of the {@literal filename} parameter (or the value of the
	 * {@literal filename*} one decoded as defined in the RFC 5987), or {@code null} if not defined.
	 */
	@Nullable
	public String getFilename() {
		return this.filename;
	}

	/**
	 * Return the charset defined in {@literal filename*} parameter, or {@code null} if not defined.
	 */
	@Nullable
	public Charset getCharset() {
		return this.charset;
	}

	/**
	 * Return the value of the {@literal size} parameter, or {@code null} if not defined.
	 */
	@Nullable
	public Long getSize() {
		return this.size;
	}

	/**
	 * Return the value of the {@literal creation-date} parameter, or {@code null} if not defined.
	 */
	@Nullable
	public ZonedDateTime getCreationDate() {
		return this.creationDate;
	}

	/**
	 * Return the value of the {@literal modification-date} parameter, or {@code null} if not defined.
	 */
	@Nullable
	public ZonedDateTime getModificationDate() {
		return this.modificationDate;
	}

	/**
	 * Return the value of the {@literal read-date} parameter, or {@code null} if not defined.
	 */
	@Nullable
	public ZonedDateTime getReadDate() {
		return this.readDate;
	}


	@Override
	public boolean equals(Object other) {
		if (this == other) {
			return true;
		}
		if (!(other instanceof ContentDisposition)) {
			return false;
		}
		ContentDisposition otherCd = (ContentDisposition) other;
		return (ObjectUtils.nullSafeEquals(this.type, otherCd.type) &&
				ObjectUtils.nullSafeEquals(this.name, otherCd.name) &&
				ObjectUtils.nullSafeEquals(this.filename, otherCd.filename) &&
				ObjectUtils.nullSafeEquals(this.charset, otherCd.charset) &&
				ObjectUtils.nullSafeEquals(this.size, otherCd.size) &&
				ObjectUtils.nullSafeEquals(this.creationDate, otherCd.creationDate)&&
				ObjectUtils.nullSafeEquals(this.modificationDate, otherCd.modificationDate)&&
				ObjectUtils.nullSafeEquals(this.readDate, otherCd.readDate));
	}

	@Override
	public int hashCode() {
		int result = ObjectUtils.nullSafeHashCode(this.type);
		result = 31 * result + ObjectUtils.nullSafeHashCode(this.name);
		result = 31 * result + ObjectUtils.nullSafeHashCode(this.filename);
		result = 31 * result + ObjectUtils.nullSafeHashCode(this.charset);
		result = 31 * result + ObjectUtils.nullSafeHashCode(this.size);
		result = 31 * result + (creationDate != null ? creationDate.hashCode() : 0);
		result = 31 * result + (modificationDate != null ? modificationDate.hashCode() : 0);
		result = 31 * result + (readDate != null ? readDate.hashCode() : 0);
		return result;
	}

	/**
	 * Return the header value for this content disposition as defined in RFC 2183.
	 * @see #parse(String)
	 */
	@Override
	public String toString() {
		StringBuilder sb = new StringBuilder();
		if (this.type != null) {
			sb.append(this.type);
		}
		if (this.name != null) {
			sb.append("; name=\"");
			sb.append(this.name).append('\"');
		}
		if (this.filename != null) {
			if(this.charset == null || StandardCharsets.US_ASCII.equals(this.charset)) {
				sb.append("; filename=\"");
				sb.append(this.filename).append('\"');
			}
			else {
				sb.append("; filename*=");
				sb.append(encodeHeaderFieldParam(this.filename, this.charset));
			}
		}
		if (this.size != null) {
			sb.append("; size=");
			sb.append(this.size);
		}
		if (this.creationDate != null) {
			sb.append("; creation-date=\"");
			sb.append(RFC_1123_DATE_TIME.format(this.creationDate));
			sb.append('\"');
		}
		if (this.modificationDate != null) {
			sb.append("; modification-date=\"");
			sb.append(RFC_1123_DATE_TIME.format(this.modificationDate));
			sb.append('\"');
		}
		if (this.readDate != null) {
			sb.append("; read-date=\"");
			sb.append(RFC_1123_DATE_TIME.format(this.readDate));
			sb.append('\"');
		}
		return sb.toString();
	}


	/**
	 * Return a builder for a {@code ContentDisposition}.
	 * @param type the disposition type like for example {@literal inline},
	 * {@literal attachment}, or {@literal form-data}
	 * @return the builder
	 */
	public static Builder builder(String type) {
		return new BuilderImpl(type);
	}

	/**
	 * Return an empty content disposition.
	 */
	public static ContentDisposition empty() {
		return new ContentDisposition("", null, null, null, null, null, null, null);
	}

	/**
	 * Parse a {@literal Content-Disposition} header value as defined in RFC 2183.
	 * @param contentDisposition the {@literal Content-Disposition} header value
	 * @return the parsed content disposition
	 * @see #toString()
	 */
	public static ContentDisposition parse(String contentDisposition) {
		List<String> parts = tokenize(contentDisposition);
		String type = parts.get(0);
		String name = null;
		String filename = null;
		Charset charset = null;
		Long size = null;
		ZonedDateTime creationDate = null;
		ZonedDateTime modificationDate = null;
		ZonedDateTime readDate = null;
		for (int i = 1; i < parts.size(); i++) {
			String part = parts.get(i);
			int eqIndex = part.indexOf('=');
			if (eqIndex != -1) {
				String attribute = part.substring(0, eqIndex);
				String value = (part.startsWith("\"", eqIndex + 1) && part.endsWith("\"") ?
						part.substring(eqIndex + 2, part.length() - 1) :
						part.substring(eqIndex + 1, part.length()));
				if (attribute.equals("name") ) {
					name = value;
				}
				else if (attribute.equals("filename*") ) {
					filename = decodeHeaderFieldParam(value);
					charset = Charset.forName(value.substring(0, value.indexOf('\'')));
					Assert.isTrue(UTF_8.equals(charset) || ISO_8859_1.equals(charset),
							"Charset should be UTF-8 or ISO-8859-1");
				}
				else if (attribute.equals("filename") && (filename == null)) {
					filename = value;
				}
				else if (attribute.equals("size") ) {
					size = Long.parseLong(value);
				}
				else if (attribute.equals("creation-date")) {
					try {
						creationDate = ZonedDateTime.parse(value, RFC_1123_DATE_TIME);
					}
					catch (DateTimeParseException ex) {
						// ignore
					}
				}
				else if (attribute.equals("modification-date")) {
					try {
						modificationDate = ZonedDateTime.parse(value, RFC_1123_DATE_TIME);
					}
					catch (DateTimeParseException ex) {
						// ignore
					}
				}
				else if (attribute.equals("read-date")) {
					try {
						readDate = ZonedDateTime.parse(value, RFC_1123_DATE_TIME);
					}
					catch (DateTimeParseException ex) {
						// ignore
					}
				}
			}
			else {
				throw new IllegalArgumentException("Invalid content disposition format");
			}
		}
		return new ContentDisposition(type, name, filename, charset, size, creationDate, modificationDate, readDate);
	}

	private static List<String> tokenize(String headerValue) {
		int index = headerValue.indexOf(';');
		String type = (index >= 0 ? headerValue.substring(0, index) : headerValue).trim();
		if (type.isEmpty()) {
			throw new IllegalArgumentException("Content-Disposition header must not be empty");
		}
		List<String> parts = new ArrayList<>();
		parts.add(type);
		if (index >= 0) {
			do {
				int nextIndex = index + 1;
				boolean quoted = false;
				while (nextIndex < headerValue.length()) {
					char ch = headerValue.charAt(nextIndex);
					if (ch == ';') {
						if (!quoted) {
							break;
						}
					}
					else if (ch == '"') {
						quoted = !quoted;
					}
					nextIndex++;
				}
				String part = headerValue.substring(index + 1, nextIndex).trim();
				if (!part.isEmpty()) {
					parts.add(part);
				}
				index = nextIndex;
			}
			while (index < headerValue.length());
		}
		return parts;
	}

	/**
	 * Decode the given header field param as describe in RFC 5987.
	 * <p>Only the US-ASCII, UTF-8 and ISO-8859-1 charsets are supported.
	 * @param input the header field param
	 * @return the encoded header field param
	 * @see <a href="https://tools.ietf.org/html/rfc5987">RFC 5987</a>
	 */
	private static String decodeHeaderFieldParam(String input) {
		Assert.notNull(input, "Input String should not be null");
		int firstQuoteIndex = input.indexOf('\'');
		int secondQuoteIndex = input.indexOf('\'', firstQuoteIndex + 1);
		// US_ASCII
		if (firstQuoteIndex == -1 || secondQuoteIndex == -1) {
			return input;
		}
		Charset charset = Charset.forName(input.substring(0, firstQuoteIndex));
		Assert.isTrue(UTF_8.equals(charset) || ISO_8859_1.equals(charset),
				"Charset should be UTF-8 or ISO-8859-1");
		byte[] value = input.substring(secondQuoteIndex + 1, input.length()).getBytes(charset);
		ByteArrayOutputStream bos = new ByteArrayOutputStream();
		int index = 0;
		while (index < value.length) {
			byte b = value[index];
			if (isRFC5987AttrChar(b)) {
				bos.write((char) b);
				index++;
			}
			else if (b == '%') {
				char[] array = { (char)value[index + 1], (char)value[index + 2]};
				bos.write(Integer.parseInt(String.valueOf(array), 16));
				index+=3;
			}
			else {
				throw new IllegalArgumentException("Invalid header field parameter format (as defined in RFC 5987)");
			}
		}
		return new String(bos.toByteArray(), charset);
	}

	private static boolean isRFC5987AttrChar(byte c) {
		return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
				c == '!' || c == '#' || c == '$' || c == '&' || c == '+' || c == '-' ||
				c == '.' || c == '^' || c == '_' || c == '`' || c == '|' || c == '~';
	}

	/**
	 * Encode the given header field param as describe in RFC 5987.
	 * @param input the header field param
	 * @param charset the charset of the header field param string,
	 * only the US-ASCII, UTF-8 and ISO-8859-1 charsets are supported
	 * @return the encoded header field param
	 * @see <a href="https://tools.ietf.org/html/rfc5987">RFC 5987</a>
	 */
	private static String encodeHeaderFieldParam(String input, Charset charset) {
		Assert.notNull(input, "Input String should not be null");
		Assert.notNull(charset, "Charset should not be null");
		if (StandardCharsets.US_ASCII.equals(charset)) {
			return input;
		}
		Assert.isTrue(UTF_8.equals(charset) || ISO_8859_1.equals(charset),
				"Charset should be UTF-8 or ISO-8859-1");
		byte[] source = input.getBytes(charset);
		int len = source.length;
		StringBuilder sb = new StringBuilder(len << 1);
		sb.append(charset.name());
		sb.append("''");
		for (byte b : source) {
			if (isRFC5987AttrChar(b)) {
				sb.append((char) b);
			}
			else {
				sb.append('%');
				char hex1 = Character.toUpperCase(Character.forDigit((b >> 4) & 0xF, 16));
				char hex2 = Character.toUpperCase(Character.forDigit(b & 0xF, 16));
				sb.append(hex1);
				sb.append(hex2);
			}
		}
		return sb.toString();
	}


	/**
	 * A mutable builder for {@code ContentDisposition}.
	 */
	public interface Builder {

		/**
		 * Set the value of the {@literal name} parameter
		 */
		Builder name(String name);

		/**
		 * Set the value of the {@literal filename} parameter
		 */
		Builder filename(String filename);

		/**
		 * Set the value of the {@literal filename*} that will be encoded as
		 * defined in the RFC 5987. Only the US-ASCII, UTF-8 and ISO-8859-1
		 * charsets are supported.
		 * <p><strong>Note:</strong> Do not use this for a
		 * {@code "multipart/form-data"} requests as per
		 * <a link="https://tools.ietf.org/html/rfc7578#section-4.2">RFC 7578, Section 4.2</a>
		 * and also RFC 5987 itself mentions it does not apply to multipart
		 * requests.
		 */
		Builder filename(String filename, Charset charset);

		/**
		 * Set the value of the {@literal size} parameter
		 */
		Builder size(Long size);

		/**
		 * Set the value of the {@literal creation-date} parameter.
		 */
		Builder creationDate(ZonedDateTime creationDate);

		/**
		 * Set the value of the {@literal modification-date} parameter.
		 */
		Builder modificationDate(ZonedDateTime modificationDate);

		/**
		 * Set the value of the {@literal read-date} parameter.
		 */
		Builder readDate(ZonedDateTime readDate);

		/**
		 * Build the content disposition
		 */
		ContentDisposition build();
	}


	private static class BuilderImpl implements Builder {

		private String type;

		@Nullable
		private String name;

		@Nullable
		private String filename;

		@Nullable
		private Charset charset;

		@Nullable
		private Long size;

		@Nullable
		private ZonedDateTime creationDate;

		@Nullable
		private ZonedDateTime modificationDate;

		@Nullable
		private ZonedDateTime readDate;

		public BuilderImpl(String type) {
			Assert.hasText(type, "'type' must not be not empty");
			this.type = type;
		}

		@Override
		public Builder name(String name) {
			this.name = name;
			return this;
		}

		@Override
		public Builder filename(String filename) {
			this.filename = filename;
			return this;
		}

		@Override
		public Builder filename(String filename, Charset charset) {
			this.filename = filename;
			this.charset = charset;
			return this;
		}

		@Override
		public Builder size(Long size) {
			this.size = size;
			return this;
		}

		@Override
		public Builder creationDate(ZonedDateTime creationDate) {
			this.creationDate = creationDate;
			return this;
		}

		@Override
		public Builder modificationDate(ZonedDateTime modificationDate) {
			this.modificationDate = modificationDate;
			return this;
		}

		@Override
		public Builder readDate(ZonedDateTime readDate) {
			this.readDate = readDate;
			return this;
		}

		@Override
		public ContentDisposition build() {
			return new ContentDisposition(this.type, this.name, this.filename, this.charset,
					this.size, this.creationDate, this.modificationDate, this.readDate);
		}
	}

}
