package com.fasterxml.jackson.core.io;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.nio.charset.Charset;
import java.util.Objects;

Abstraction that encloses information about content being processed -- input source or output target, streaming or not -- for the purpose of including pertinent information in location (see JsonLocation) objections, most commonly to be printed out as part of Exception messages. 
Since:
2.13/**
 * Abstraction that encloses information about content being processed --
 * input source or output target, streaming or
 * not -- for the purpose of including pertinent information in
 * location (see {@link com.fasterxml.jackson.core.JsonLocation})
 * objections, most commonly to be printed out as part of {@code Exception}
 * messages.
 *
 * @since 2.13
 */
public class ContentReference
    // sort of: we will read back as "UNKNOWN"
    implements java.io.Serializable
{
    private static final long serialVersionUID = 1L;

    
Constant that may be used when source/target content is not known
(or not exposed).

NOTE: As of 2.13 assume to contain Binary content, meaning that no
content snippets will be included.
/**
     * Constant that may be used when source/target content is not known
     * (or not exposed).
     *<p>
     * NOTE: As of 2.13 assume to contain Binary content, meaning that no
     * content snippets will be included.
     */
    protected final static ContentReference UNKNOWN_CONTENT =
            new ContentReference(false, null);

    
Include at most first 500 characters/bytes from contents; should be enough
to give context, but not cause unfortunate side effects in things like
logs.
Since:
2.9/**
     * Include at most first 500 characters/bytes from contents; should be enough
     * to give context, but not cause unfortunate side effects in things like
     * logs.
     *
     * @since 2.9
     */
    public static final int DEFAULT_MAX_CONTENT_SNIPPET = 500;

    
Reference to the actual underlying content.
/**
     * Reference to the actual underlying content.
     */
    protected final transient Object _rawContent;

    
For static content, indicates offset from the beginning of static array. -1 if not in use. /**
     * For static content, indicates offset from the beginning
     * of static array.
     * {@code -1} if not in use.
     */
    protected final int _offset;

    
For static content, indicates length of content in the static array. -1 if not in use. /**
     * For static content, indicates length of content in
     * the static array.
     * {@code -1} if not in use.
     */
    protected final int _length;

    
Marker flag to indicate whether included content is textual or not:
this is taken to mean, by default, that a snippet of content may be
displayed for exception messages. 
/**
     * Marker flag to indicate whether included content is textual or not:
     * this is taken to mean, by default, that a snippet of content may be
     * displayed for exception messages. 
     */
    protected final boolean _isContentTextual;

    /*
    /**********************************************************************
    /* Life-cycle
    /**********************************************************************
     */

    protected ContentReference(boolean isContentTextual, Object rawContent) {
        this(isContentTextual, rawContent, -1, -1);
    }

    protected ContentReference(boolean isContentTextual, Object rawContent,
            int offset, int length)
    {
        _isContentTextual = isContentTextual;
        _rawContent = rawContent;
        _offset = offset;
        _length = length;
    }

    
Accessor for getting a placeholder for cases where actual content
is not known (or is not something that system wants to expose).
Returns:
Placeholder "unknown" (or "empty") instance to use instead of null reference/**
     * Accessor for getting a placeholder for cases where actual content
     * is not known (or is not something that system wants to expose).
     *
     * @return Placeholder "unknown" (or "empty") instance to use instead of
     *    {@code null} reference
     */
    public static ContentReference unknown() {
        return UNKNOWN_CONTENT;
    }

    public static ContentReference construct(boolean isContentTextual, Object rawContent) {
        return new ContentReference(isContentTextual, rawContent);
    }

    public static ContentReference construct(boolean isContentTextual, Object rawContent,
            int offset, int length) {
        return new ContentReference(isContentTextual, rawContent, offset, length);
    }

    
Factory method for legacy code to use for constructing instances to
content about which only minimal amount of information is available.
Assumed not to contain textual content (no snippet displayed).
Params:
isContentTextual – Is raw content assumed to have textual content (true) or binary (false)
rawContent – Underlying raw content access
Returns:
Instance with minimal information about content (basically just
   raw content reference without offsets/**
     * Factory method for legacy code to use for constructing instances to
     * content about which only minimal amount of information is available.
     * Assumed not to contain textual content (no snippet displayed).
     *
     * @param isContentTextual Is raw content assumed to have textual content
     *    ({@code true}) or binary ({@code false})
     * @param rawContent Underlying raw content access
     *
     * @return Instance with minimal information about content (basically just
     *    raw content reference without offsets
     */
    public static ContentReference rawReference(boolean isContentTextual,
            Object rawContent)
    {
        // Just to avoid russian-doll-nesting, let's:
        if (rawContent instanceof ContentReference) {
            return (ContentReference) rawContent;
        }
        return new ContentReference(isContentTextual, rawContent);
    }

    public static ContentReference rawReference(Object rawContent) {
        return rawReference(false, rawContent);
    }

    /*
    /**********************************************************************
    /* Serializable overrides
    /**********************************************************************
     */    
    
    // For JDK serialization: can/should not retain raw content, so need
    // not read or write anything

    private void readObject(ObjectInputStream in) throws IOException {
        // nop: but must override the method
    }

    private void writeObject(ObjectOutputStream out) throws IOException {
        // nop: but must override the method
    }

    protected Object readResolve() {
        return UNKNOWN_CONTENT;
    }

    /*
    /**********************************************************************
    /* Basic accessors
    /**********************************************************************
     */    

    public boolean hasTextualContent() {
        return _isContentTextual;
    }

    public Object getRawContent() {
        return _rawContent;
    }

    public int contentOffset() { return _offset; }
    public int contentLength() { return _length; }

    
Internal accessor, overridable, used for checking length (in units in
which content is counted, either bytes or chars) to use for truncation
(so as not to include full content for humongous sources or targets)
Returns:
Maximum content snippet to include before truncating/**
     * Internal accessor, overridable, used for checking length (in units in
     * which content is counted, either bytes or chars) to use for truncation
     * (so as not to include full content for humongous sources or targets)
     *
     * @return Maximum content snippet to include before truncating
     */
    protected int maxContentSnippetLength() {
        return DEFAULT_MAX_CONTENT_SNIPPET;
    }

    /*
    /**********************************************************************
    /* Method for constructing descriptions
    /**********************************************************************
     */    

    
Method for constructing a "source description" when content represented
by this reference is read.
Returns:
Description constructed/**
     * Method for constructing a "source description" when content represented
     * by this reference is read.
     *
     * @return Description constructed
     */
    public String buildSourceDescription() {
        return appendSourceDescription(new StringBuilder(200)).toString();
    }

    
Method for appending a "source description" when content represented
by this reference is read.
Params:
sb – StringBuilder to append description to
Returns:
StringBuilder passed as argument (for call chaining)/**
     * Method for appending a "source description" when content represented
     * by this reference is read.
     *
     * @param sb StringBuilder to append description to
     *
     * @return StringBuilder passed as argument (for call chaining)
     */
    public StringBuilder appendSourceDescription(StringBuilder sb)
    {
        final Object srcRef = getRawContent();

        if (srcRef == null) {
            sb.append("UNKNOWN");
            return sb;
        }
        // First, figure out what name to use as source type
        Class<?> srcType = (srcRef instanceof Class<?>) ?
                ((Class<?>) srcRef) : srcRef.getClass();
        String tn = srcType.getName();
        // standard JDK types without package
        if (tn.startsWith("java.")) {
            tn = srcType.getSimpleName();
        } else if (srcRef instanceof byte[]) { // then some other special cases
            tn = "byte[]";
        } else if (srcRef instanceof char[]) {
            tn = "char[]";
        }
        sb.append('(').append(tn).append(')');

        // and then, include (part of) contents for selected types
        // (never for binary-format data)
        if (hasTextualContent()) {
            String unitStr = " chars";
            String trimmed;

            // poor man's tuple...
            final int maxLen = maxContentSnippetLength();
            int[] offsets = new int[] { contentOffset(), contentLength() };

            if (srcRef instanceof CharSequence) {
                trimmed = _truncate((CharSequence) srcRef, offsets, maxLen);
            } else if (srcRef instanceof char[]) {
                trimmed = _truncate((char[]) srcRef, offsets, maxLen);
            } else if (srcRef instanceof byte[]) {
                trimmed = _truncate((byte[]) srcRef, offsets, maxLen);
                unitStr = " bytes";
            } else {
                trimmed = null;
            }
            if (trimmed != null) {
                _append(sb, trimmed);
                if (offsets[1] > maxLen) {
                    sb.append("[truncated ").append(offsets[1] - maxLen).append(unitStr).append(']');
                }
            }
        } else {
            // What should we do with binary content? Indicate length, if possible
            if (srcRef instanceof byte[]) {
                int length = contentLength();
                // -1 is marker for "till the end" (should we consider offset then, too?)
                if (length < 0) {
                    length = ((byte[]) srcRef).length;
                }
                sb.append('[')
                    .append(length)
                    .append(" bytes]");
            }
        }
        return sb;
    }

    protected String _truncate(CharSequence cs, int[] offsets, int maxSnippetLen) {
        _truncateOffsets(offsets, cs.length());
        final int start = offsets[0];
        final int length = Math.min(offsets[1], maxSnippetLen);
        return cs.subSequence(start, start + length).toString();
    }

    protected String _truncate(char[] cs, int[] offsets, int maxSnippetLen) {
        _truncateOffsets(offsets, cs.length);
        final int start = offsets[0];
        final int length = Math.min(offsets[1], maxSnippetLen);
        return new String(cs, start, length);
    }

    protected String _truncate(byte[] b, int[] offsets, int maxSnippetLen) {
        _truncateOffsets(offsets, b.length);
        final int start = offsets[0];
        final int length = Math.min(offsets[1], maxSnippetLen);
        return new String(b, start, length, Charset.forName("UTF-8"));
    }

    // Method that is given alleged start/offset pair and needs to adjust
    // these to fit
    protected void _truncateOffsets(int[] offsets, int actualLength) {
        int start = offsets[0];
        // first, move start to be within area
        if (start < 0) { // means effectively "start at beginning"
            start = 0;
        } else if (start >= actualLength) {
            start = actualLength;
        }
        offsets[0] = start;

        // And then ensure that we obey maximum physical length restriction
        int length = offsets[1];
        final int maxLength = actualLength - start;
        if ((length < 0) || (length > maxLength)) {
            offsets[1] = maxLength;
        }
    }

    protected int _append(StringBuilder sb, String content) {
        sb.append('"');
        // [core#658]: make sure to escape non-printable
        for (int i = 0, end = content.length(); i < end; ++i) {
            // 06-Apr-2021, tatu: Gee... there is no "Character.isPrintable()",
            //   and from what I can see things get rather complicated trying
            //   to figure out proper way. Hence, we'll do this
            char ch = content.charAt(i);
            if (!Character.isISOControl(ch) || !_appendEscaped(sb, ch)) {
                sb.append(ch);
            }
        }
        sb.append('"');
        return content.length();
    }

    protected boolean _appendEscaped(StringBuilder sb, int ctrlChar) {
        // We'll escape most, but NOT regular CR or LF
        if (ctrlChar == '\r' || ctrlChar == '\n') {
            return false;
        }
        sb.append('\\');
        sb.append('u');
        sb.append(CharTypes.hexToChar((ctrlChar >> 12) & 0xF));
        sb.append(CharTypes.hexToChar((ctrlChar >> 8) & 0xF));
        sb.append(CharTypes.hexToChar((ctrlChar >> 4) & 0xF));
        sb.append(CharTypes.hexToChar(ctrlChar & 0xF));
        return true;
    }
    
    /*
    /**********************************************************************
    /* Standard method overrides
    /**********************************************************************
     */    

    // Just needed for JsonLocation#equals(): although it'd seem we only need
    // to care about identity, for backwards compatibility better compare
    // bit more
    @Override
    public boolean equals(Object other)
    {
        if (other == this) return true;
        if (other == null) return false;
        if (!(other instanceof ContentReference)) return false;
        ContentReference otherSrc = (ContentReference) other;

        return _rawContent == otherSrc._rawContent;
    }

    // Just to appease LGTM...
    @Override
    public int hashCode() {
        return Objects.hashCode(_rawContent);
    }
}