/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
package org.mozilla.jss.asn1;

import java.io.ByteArrayInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Vector;

/**
 * An ASN.1 SEQUENCE. This class is an ordered collection of ASN.1 values.
 * It has an interface similar to a Java <code>Vector</code>.
 * Null entries may be added; they will be skipped when encoded.
 */
public class SEQUENCE extends SET implements ASN1Value {

    public static final Tag TAG = new Tag(Tag.Class.UNIVERSAL, 16);

    @Override
    public Tag getTag() {
        return TAG;
    }

    public static Template getTemplate() {
        return new Template();
    }

    /**
     * Writes the DER encoding to the given output stream,
     * using the given implicit tag.
     */
    @Override
    public void encode(Tag implicitTag, OutputStream ostream)
            throws IOException {
        BERencode(implicitTag, ostream);
    }

    // SET.Element and SEQUENCE.Element are identical types.  We could
    // have just reused SET.Element, but that would have been a bit
    // confusing for users.
    private static class Element extends SET.Element {
        public Element(ASN1Value val) {
            super(val);
        }

        public Element(Tag implicitTag, ASN1Value val) {
            super(implicitTag, val);
        }
    }

    /**
     * A class for constructing a <code>SEQUENCE</code> from its BER encoding.
     * It is an ordered collection of sub-templates. Each sub-template can be
     * marked optional, or a default value can be given.
     */
    public static class Template implements ASN1Template {

        private Vector<Element> elements = new Vector<>();

        private void addElement(Element el) {
            elements.addElement(el);
        }

        private void insertElementAt(Element e, int index) {
            elements.insertElementAt(e, index);
        }

        /**
         * Adds a sub-template to the end of this SEQUENCE template. For example,
         * if the ASN.1 included:
         * 
         * <pre>
         * MySequence ::= SEQUENCE {
         *      item        SubType,
         *      ... }
         * </pre>
         * 
         * the "item" element would be added to the MySequence template with:
         * 
         * <pre>
         * mySequence.addElement(new SubType.Template());
         * </pre>
         * 
         * @param t Sub-template.
         */
        public void addElement(ASN1Template t) {
            addElement(new Element(null, t, false));
        }

        /**
         * Inserts the template at the given index.
         * 
         * @param t Sub-template.
         * @param index Index.
         */
        public void insertElementAt(ASN1Template t, int index) {
            insertElementAt(new Element(null, t, false), index);
        }

        /**
         * Adds a sub-template to the end of this SEQUENCE template, with the
         * given implicit tag. For example, if the ASN.1 were:
         * 
         * <pre>
         * MySequence ::= SEQUENCE {
         *      item        [0] IMPLICIT  SubType,
         *      ... }
         * </pre>
         * 
         * the "item" element would be added to the MySequence template with:
         * 
         * <pre>
         * mySequence.addElement(new Tag(0), new SubType.Template());
         * </pre>
         * 
         * @param implicitTag Implicit tag.
         * @param t Sub-template.
         */
        public void addElement(Tag implicitTag, ASN1Template t) {
            addElement(new Element(implicitTag, t, false));
        }

        /**
         * Inserts the template with the given implicit tag at the given index.
         * 
         * @param implicit Implicit tag.
         * @param t Sub-Template.
         * @param index Index.
         */
        public void insertElementAt(Tag implicit, ASN1Template t,
                int index) {
            insertElementAt(new Element(implicit, t, false), index);
        }

        /**
         * Adds an optional sub-template. For example, if the ASN.1 were:
         * 
         * <pre>
         * MySequence ::= SEQUENCE {
         *      item        SubType OPTIONAL,
         *      ... }
         * </pre>
         * 
         * the "item" element would be added to the MySequence template with:
         * 
         * <pre>
         * mySequence.addOptionalElement(new SubType.Template());
         * </pre>
         * 
         * @param t Optional sub-template.
         */
        public void addOptionalElement(ASN1Template t) {
            addElement(new Element(null, t, true));
        }

        /**
         * Inserts the optional template at the given index.
         * 
         * @param t Optional sub-template.
         * @param index Index.
         */
        public void insertOptionalElementAt(ASN1Template t, int index) {
            insertElementAt(new Element(null, t, true), index);
        }

        /**
         * Adds an optional sub-template with an implicit tag. For example,
         * if the ASN.1 were:
         * 
         * <pre>
         * MySequence ::= SEQUENCE {
         *      item        [0] IMPLICIT SubType OPTIONAL,
         *      ... }
         * </pre>
         * 
         * the "item" element would be added to the MySequence template with:
         * 
         * <pre>
         * mySequence.addOptionalElement(new SubType.Template());
         * </pre>
         * 
         * @param implicitTag Implicit tag.
         * @param t Optional sub-template.
         */
        public void addOptionalElement(Tag implicitTag, ASN1Template t) {
            addElement(new Element(implicitTag, t, true));
        }

        /**
         * Inserts the optional template with the given default
         * value at the given index.
         * 
         * @param implicit Implicit tag.
         * @param t Optional sub-template.
         * @param index Index.
         */
        public void insertOptionalElementAt(Tag implicit, ASN1Template t,
                int index) {
            insertElementAt(new Element(implicit, t, true), index);
        }

        /**
         * Adds a sub-template with a default value. For example,
         * if the ASN.1 were:
         * 
         * <pre>
         * MySequence ::= SEQUENCE {
         *      version     INTEGER DEFAULT 1,
         *      ... }
         * </pre>
         * 
         * the "item" element would be added to the MySequence template with:
         * 
         * <pre>
         * mySequence.addElement(new INTEGER.Template(), new INTEGER(1));
         * </pre>
         * 
         * @param t Sub-template.
         * @param def The default value for this field, which will be used if
         *            no value is supplied by the encoded structure. It must be of
         *            the same type as what the template would produce.
         */
        public void addElement(ASN1Template t, ASN1Value def) {
            addElement(new Element(null, t, def));
        }

        /**
         * Inserts the template with the given default
         * value at the given index.
         * 
         * @param t Sub-template.
         * @param def Default value.
         * @param index Index.
         */
        public void insertElementAt(ASN1Template t, ASN1Value def, int index) {
            insertElementAt(new Element(null, t, def), index);
        }

        /**
         * Adds a sub-template with a default value and an implicit tag.
         * For example, if the ASN.1 were:
         * 
         * <pre>
         * MySequence ::= SEQUENCE {
         *      version     [0] IMPLICIT INTEGER DEFAULT 1,
         *      ... }
         * </pre>
         * 
         * the "item" element would be added to the MySequence template with:
         * 
         * <pre>
         * mySequence.addElement(new Tag(0), new INTEGER.Template(),
         *         new INTEGER(1));
         * </pre>
         * 
         * @param implicitTag Implicit tag.
         * @param t Sub-template.
         * @param def The default value for this field, which will be used if
         *            no value is supplied by the encoded structure. It must be of
         *            the same type as what the template would produce.
         */
        public void addElement(Tag implicitTag, ASN1Template t, ASN1Value def) {
            addElement(new Element(implicitTag, t, def));
        }

        /**
         * Inserts the template with the given implicit tag and given default
         * value at the given index.
         * 
         * @param implicit Implicit tag.
         * @param t Sub-template.
         * @param def Default value.
         * @param index Index.
         */
        public void insertElementAt(Tag implicit, ASN1Template t, ASN1Value def,
                int index) {
            insertElementAt(new Element(implicit, t, def), index);
        }

        /**
         * Returns the implicit tag of the item stored at the given index.
         * May be NULL if no implicit tag was specified.
         * 
         * @param index Index.
         * @return Tag.
         */
        public Tag implicitTagAt(int index) {
            return elements.elementAt(index).getImplicitTag();
        }

        /**
         * Returns the sub-template stored at the given index.
         * 
         * @param index Index.
         * @return Sub-template.
         */
        public ASN1Template templateAt(int index) {
            return elements.elementAt(index).getTemplate();
        }

        /**
         * Returns whether the sub-template at the given index is optional.
         * 
         * @param index Index.
         * @return True if the sub-template is optional.
         */
        public boolean isOptionalAt(int index) {
            return elements.elementAt(index).isOptional();
        }

        /**
         * Returns the default value for the sub-template at the given index.
         * May return NULL if no default value was specified.
         * 
         * @param index Index.
         * @return Default value.
         */
        public ASN1Value defaultAt(int index) {
            return elements.elementAt(index).getDefault();
        }

        /**
         * @return The number of elements in this SEQUENCE template.
         */
        public int size() {
            return elements.size();
        }

        /**
         * Removes all sub-templates from this SEQUENCE template.
         */
        public void removeAllElements() {
            elements.removeAllElements();
        }

        /**
         * Removes the sub-template at the given index.
         * 
         * @param index Index.
         */
        public void removeElementAt(int index) {
            elements.removeElementAt(index);
        }

        Tag getTag() {
            return SEQUENCE.TAG;
        }

        @Override
        public boolean tagMatch(Tag tag) {
            return (tag.equals(SEQUENCE.TAG));
        }

        /**
         * Decodes a SEQUENCE from its BER encoding.
         * 
         * @param istream Input stream.
         */
        @Override
        public ASN1Value decode(InputStream istream)
                throws IOException, InvalidBERException {
            return decode(getTag(), istream);
        }

        /**
         * Decodes a SEQUENCE from its BER encoding, where the SEQUENCE itself has
         * an implicit tag.
         * 
         * @param tag Tag.
         * @param istream Input stream.
         */
        @Override
        public ASN1Value decode(Tag tag, InputStream istream)
                throws IOException, InvalidBERException {
            int index = 0;

            try {
                ASN1Header header = new ASN1Header(istream);

                header.validate(tag, Form.CONSTRUCTED);

                // will be -1 for indefinite encoding
                long remainingContent = header.getContentLength();

                boolean repeatableElement = false;
                SEQUENCE seq = new SEQUENCE();
                ASN1Header lookAhead = null;

                // go through the whole template
                for (index = 0; index < size(); index++) {

                    // find out about the next item
                    if (remainingContent == 0) {
                        lookAhead = null;
                    } else {
                        // remainingContent > 0 or remainingContent == -1, which means
                        // indefinite encoding.
                        lookAhead = ASN1Header.lookAhead(istream);
                    }

                    // skip over items that don't match.  Hopefully they are
                    // optional or have a default.  Otherwise, it's an error.
                    Element e = elements.elementAt(index);
                    if ((lookAhead == null) || lookAhead.isEOC() ||
                            !e.tagMatch(lookAhead.getTag())) {
                        if (e.isRepeatable()) {
                            repeatableElement = true;
                        } else if (e.isOptional()) {
                            // put an empty entry into the SEQUENCE
                            SEQUENCE.Element se = new SEQUENCE.Element(null, null);
                            seq.addElement(null);
                        } else if (e.getDefault() != null) {
                            // use the default
                            seq.addElement(e.getDefault());
                        } else {
                            String tagDesc;
                            if (lookAhead == null) {
                                tagDesc = "(null)";
                            } else {
                                tagDesc = lookAhead.getTag().toString();
                            }
                            throw new InvalidBERException("Missing item #" + index +
                                    ": found " + tagDesc);
                        }
                        continue;
                    }

                    // Decode this element
                    ASN1Template t = e.getTemplate();
                    ASN1Value val;

                    try (CountingStream countstream = new CountingStream(istream)) {

                        if (e.getImplicitTag() == null) {
                            val = t.decode(countstream);
                        } else {
                            val = t.decode(e.getImplicitTag(), countstream);
                        }

                        // Decrement remaining count
                        long len = countstream.getNumRead();
                        if (remainingContent != -1) {
                            if (remainingContent < len) {
                                // this item went past the end of the SEQUENCE
                                throw new InvalidBERException("Item went " +
                                        (len - remainingContent) + " bytes past the end of" +
                                        " the SEQUENCE");
                            }
                            remainingContent -= len;
                        }
                    }

                    // Store this element in the SEQUENCE
                    if (e.producesOutput()) {
                        if (e.getImplicitTag() == null) {
                            // no implicit tag
                            seq.addElement(val);
                        } else {
                            // there is an implicit tag
                            seq.addElement(e.getImplicitTag(), val);
                        }
                    }

                    // If this element is repeatable, don't go on to the next element
                    if (e.isRepeatable()) {
                        repeatableElement = true;
                        index--;
                    }
                }

                if (remainingContent > 0) {
                    throw new InvalidBERException("SEQUENCE is " + remainingContent +
                            " bytes longer than expected");
                }
                assert (remainingContent == 0 || remainingContent == -1);

                // If this was indefinite-length encoding, consume the end-of-contents
                if (remainingContent == -1) {
                    lookAhead = new ASN1Header(istream);
                    if (!lookAhead.isEOC()) {
                        throw new InvalidBERException("No end-of-contents marker");
                    }
                }

                // Make sure we stayed in sync
                if (!repeatableElement) {
                    assert (index == seq.size());
                }

                return seq;

            } catch (InvalidBERException e) {
                e.append("SEQUENCE(item #" + index + ")");
                throw e;
            }
        }

        /**
         * An element of a SEQUENCE template. For each sub-template, contains the
         * template, its optionality, its implicit tag, and its default value.
         */
        static class Element {

            /**
             * Creates a new element, which may or may not be optional.
             * 
             * @param implicitTag Implicit tag.
             * @param type Type.
             * @param optional Optional.
             */
            public Element(Tag implicitTag, ASN1Template type, boolean optional) {
                this(implicitTag, type, optional, true);
            }

            /**
             * Creates a new element, which may or may not be optional.
             * 
             * @param implicitTag Implicit tag.
             * @param type Type.
             * @param optional Optional.
             * @param doesProduceOutput True if produces output.
             */
            public Element(Tag implicitTag, ASN1Template type, boolean optional,
                    boolean doesProduceOutput) {
                this.type = type;
                defaultVal = null;
                this.optional = optional;
                this.implicitTag = implicitTag;
                this.doesProduceOutput = doesProduceOutput;
            }

            /**
             * Creates a new element with a default value.
             * 
             * @param implicitTag Implicit tag.
             * @param type Type.
             * @param defaultVal Default value.
             */
            public Element(Tag implicitTag, ASN1Template type, ASN1Value defaultVal) {
                this.type = type;
                this.defaultVal = defaultVal;
                optional = false;
                this.implicitTag = implicitTag;
            }

            private boolean doesProduceOutput = true;

            boolean producesOutput() {
                return doesProduceOutput;
            }

            // repeatability is provided to allow for SEQUENCE OF SIZE
            // constructs.  It is package private.
            private boolean repeatable;

            void makeRepeatable() {
                repeatable = true;
            }

            boolean isRepeatable() {
                return repeatable;
            }

            private boolean optional;

            public boolean isOptional() {
                return optional;
            }

            private Tag implicitTag = null;

            public Tag getImplicitTag() {
                return implicitTag;
            }

            public boolean tagMatch(Tag tag) {
                if (implicitTag != null) {
                    return (implicitTag.equals(tag));
                } else {
                    return type.tagMatch(tag);
                }
            }

            private ASN1Template type;

            public ASN1Template getTemplate() {
                return type;
            }

            private ASN1Value defaultVal = null;

            public ASN1Value getDefault() {
                return defaultVal;
            }
        }
    } // End of SEQUENCE.Template

    /**
     * A Template for decoding SEQUENCE OF values. The main difference between
     * a SEQUENCE.Template and a SEQUENCE.OF_Template is that a regular template
     * specifies the exact ordering, number, and type of elements of the sequence,
     * while
     * an OF_Template has an indefinite number of elements, all the same type.
     * For example, given:
     * 
     * <pre>
     * MyType ::= SEQUENCE OF Extension
     * </pre>
     * 
     * a MyType could be decoded with:
     * 
     * <pre>
     *  SEQUENCE.OF_Template myTypeTemplate = new SEQUENCE.OF_Template( new
     *      Extension.Template) );
     *  SEQUENCE seq = (SEQUENCE) myTypeTemplate.decode(someInputStream);
     * </pre>
     * 
     * The number of <code>Extension</code>s actually decoded could be found
     * with <code>seq.size()</code>.
     */
    public static class OF_Template implements ASN1Template {

        private OF_Template() {
        }

        Template template; // a normal SEQUENCE template

        public OF_Template(ASN1Template type) {
            template = new Template();
            Template.Element el = new Template.Element(null, type, true); //optional
            el.makeRepeatable();
            template.addElement(el);
        }

        public static OF_Template makeOutputlessOFTemplate(ASN1Template type) {
            OF_Template t = new OF_Template();
            t.template = new Template();
            Template.Element el = new Template.Element(null, type, true, false);
            el.makeRepeatable();
            t.template.addElement(el);
            return t;
        }

        @Override
        public boolean tagMatch(Tag tag) {
            return TAG.equals(tag);
        }

        /**
         * Decodes a SEQUENCE OF from an input stream.
         */
        @Override
        public ASN1Value decode(InputStream istream)
                throws IOException, InvalidBERException {
            return template.decode(istream);
        }

        /**
         * Decodes a SEQUENCE OF with an implicit tag from an input stream.
         */
        @Override
        public ASN1Value decode(Tag implicitTag, InputStream istream)
                throws IOException, InvalidBERException {
            return template.decode(implicitTag, istream);
        }
    }

    public static void main(String args[]) {

        try {

            if (args.length > 0) {
                // input

                Template type = new Template();
                type.addOptionalElement(new Tag(15), new INTEGER.Template());
                type.addElement(new Tag(16), new INTEGER.Template(),
                        new INTEGER(42));
                type.addElement(new INTEGER.Template());
                type.addElement(new BOOLEAN.Template());
                type.addElement(new INTEGER.Template());
                type.addOptionalElement(new Tag(12), new INTEGER.Template());
                type.addElement(new BOOLEAN.Template());
                type.addElement(new Tag(13), new INTEGER.Template(),
                        new INTEGER(53));
                type.addElement(new INTEGER.Template());
                type.addElement(new INTEGER.Template());
                type.addOptionalElement(new Tag(14), new INTEGER.Template());
                type.addElement(new OBJECT_IDENTIFIER.Template());
                type.addElement(new NULL.Template());
                type.addElement(new EXPLICIT.Template(
                        new Tag(27), new INTEGER.Template()));
                type.addElement(new ENUMERATED.Template());
                type.addElement(new OCTET_STRING.Template());
                type.addElement(new IA5String.Template());

                CHOICE.Template choice = new CHOICE.Template();
                choice.addElement(new Tag(23), new INTEGER.Template());
                choice.addElement(new BOOLEAN.Template());
                type.addElement(choice);
                type.addElement(new BIT_STRING.Template());
                type.addElement(new ANY.Template());
                type.addElement(new PrintableString.Template());
                type.addElement(new OF_Template(new INTEGER.Template()));
                type.addElement(new OF_Template(new INTEGER.Template()));

                byte[] stuff;

                try (FileInputStream fin = new FileInputStream(args[0])) {
                    System.out.println("Available: " + fin.available());
                    stuff = new byte[fin.available()];
                    ASN1Util.readFully(stuff, fin);
                }

                SEQUENCE s = null;
                for (int i = 0; i < 1; i++) {
                    s = (SEQUENCE) type.decode(new ByteArrayInputStream(stuff));
                }

                for (int i = 0; i < s.size(); i++) {
                    ASN1Value v = s.elementAt(i);
                    if (v instanceof ENUMERATED) {
                        ENUMERATED en = (ENUMERATED) v;
                        System.out.println("ENUMERATED: " + en);
                    } else if (v instanceof INTEGER) {
                        INTEGER in = (INTEGER) v;
                        System.out.println("INTEGER: " + in);
                    } else if (v instanceof BOOLEAN) {
                        BOOLEAN bo = (BOOLEAN) v;
                        System.out.println("BOOLEAN: " + bo);
                    } else if (v instanceof OBJECT_IDENTIFIER) {
                        OBJECT_IDENTIFIER oid = (OBJECT_IDENTIFIER) v;
                        System.out.println("OID: " + oid);
                    } else if (v instanceof NULL) {
                        NULL n = (NULL) v;
                        System.out.println("NULL");
                    } else if (v instanceof EXPLICIT) {
                        EXPLICIT ex = (EXPLICIT) v;
                        INTEGER in = (INTEGER) ex.getContent();
                        System.out.println("EXPLICIT [" + ex.getTag() + "]: " +
                                "INTEGER: " + in);
                    } else if (v instanceof OCTET_STRING) {
                        OCTET_STRING os = (OCTET_STRING) v;
                        byte[] bytes = os.toByteArray();
                        System.out.print("OCTET_STRING: ");
                        for (int j = 0; j < bytes.length; j++) {
                            System.out.print(bytes[j] + " ");
                        }
                        System.out.println("");
                    } else if (v instanceof CharacterString) {
                        CharacterString cs = (CharacterString) v;
                        System.out.println("String: " + cs);
                    } else if (v instanceof BIT_STRING) {
                        BIT_STRING bs = (BIT_STRING) v;
                        System.out.print("BIT_STRING: padCount=" +
                                bs.getPadCount() + " : ");
                        byte[] bits = bs.getBits();
                        for (int j = 0; j < bits.length; j++) {
                            System.out.print(bits[j] + " ");
                        }
                        System.out.println("");
                    } else if (v instanceof ANY) {
                        ANY any = (ANY) v;
                        Tag tag = any.getTag();
                        System.out.println("Got ANY, tag is " + tag);
                        ByteArrayInputStream bos = new ByteArrayInputStream(any.getEncoded());
                        INTEGER in = (INTEGER) new INTEGER.Template().decode(bos);
                        System.out.println("    INTEGER: " + in);
                    } else if (v instanceof SEQUENCE) {
                        SEQUENCE seq = (SEQUENCE) v;
                        System.out.println("SEQUENCE: ");
                        for (int j = 0; j < seq.size(); j++) {
                            INTEGER in = (INTEGER) seq.elementAt(j);
                            System.out.println("    INTEGER: " + in);
                        }
                    } else {
                        System.out.println("Unknown value");
                    }
                }

            } else {
                // output

                SEQUENCE seq = new SEQUENCE();
                seq.addElement(new INTEGER(5));
                seq.addElement(new BOOLEAN(true));
                seq.addElement(new INTEGER(-322));
                seq.addElement(new BOOLEAN(false));
                seq.addElement(new INTEGER(0));
                seq.addElement(new INTEGER("2934293834242"));
                seq.addElement(new OBJECT_IDENTIFIER(
                        new long[] { 1, 2, 127, 563, 1231982 }));
                seq.addElement(new NULL());
                seq.addElement(new EXPLICIT(new Tag(27), new INTEGER(39)));
                seq.addElement(new ENUMERATED(983));
                seq.addElement(new OCTET_STRING(new byte[] {
                        (byte) 0x0, (byte) 0xff, (byte) 0xcc }));
                seq.addElement(new IA5String("foobar"));
                seq.addElement(new Tag(23), new INTEGER(234));
                //seq.addElement( new BOOLEAN(false) );
                byte[] bits = new byte[] { (byte) 0x80, (byte) 0xff, (byte) 0x0f };
                seq.addElement(new BIT_STRING(bits, 3));
                seq.addElement(new INTEGER(82734));
                seq.addElement(new PrintableString("I'm printable??"));

                SEQUENCE nested = new SEQUENCE();
                nested.addElement(new INTEGER(5));
                nested.addElement(new INTEGER(6));
                seq.addElement(nested);

                nested = new SEQUENCE();
                seq.addElement(nested);

                seq.encode(System.out);
                System.out.flush();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}
