/*
 * Copyright (c) 2000, 2020 Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2021 Contributors to the Eclipse Foundation
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

/*
 * @(#)ASCII_UCodeESC_CharStream.java	1.3 06/28/07
 */

package com.sun.messaging.jmq.jmsselector;

/**
 * An implementation of interface CharStream, where the stream is assumed to contain only ASCII characters (with
 * java-like unicode escape processing).
 */

public final class ASCII_UCodeESC_CharStream {
    public static final boolean staticFlag = false;

    static int hexval(char c) throws java.io.IOException {
        switch (c) {
        case '0':
            return 0;
        case '1':
            return 1;
        case '2':
            return 2;
        case '3':
            return 3;
        case '4':
            return 4;
        case '5':
            return 5;
        case '6':
            return 6;
        case '7':
            return 7;
        case '8':
            return 8;
        case '9':
            return 9;

        case 'a':
        case 'A':
            return 10;
        case 'b':
        case 'B':
            return 11;
        case 'c':
        case 'C':
            return 12;
        case 'd':
        case 'D':
            return 13;
        case 'e':
        case 'E':
            return 14;
        case 'f':
        case 'F':
            return 15;
        }

        throw new java.io.IOException(); // Should never come here
    }

    public int bufpos = -1;
    int bufsize;
    int available;
    int tokenBegin;
    private int bufline[];
    private int bufcolumn[];

    private int column = 0;
    private int line = 1;

    private java.io.Reader inputStream;

    private boolean prevCharIsCR = false;
    private boolean prevCharIsLF = false;

    private char[] nextCharBuf;
    private char[] buffer;
    private int maxNextCharInd = 0;
    private int nextCharInd = -1;
    private int inBuf = 0;

    private void expandBuff(boolean wrapAround) {
        char[] newbuffer = new char[bufsize + 2048];
        int newbufline[] = new int[bufsize + 2048];
        int newbufcolumn[] = new int[bufsize + 2048];

        try {
            if (wrapAround) {
                System.arraycopy(buffer, tokenBegin, newbuffer, 0, bufsize - tokenBegin);
                System.arraycopy(buffer, 0, newbuffer, bufsize - tokenBegin, bufpos);
                buffer = newbuffer;

                System.arraycopy(bufline, tokenBegin, newbufline, 0, bufsize - tokenBegin);
                System.arraycopy(bufline, 0, newbufline, bufsize - tokenBegin, bufpos);
                bufline = newbufline;

                System.arraycopy(bufcolumn, tokenBegin, newbufcolumn, 0, bufsize - tokenBegin);
                System.arraycopy(bufcolumn, 0, newbufcolumn, bufsize - tokenBegin, bufpos);
                bufcolumn = newbufcolumn;

                bufpos += (bufsize - tokenBegin);
            } else {
                System.arraycopy(buffer, tokenBegin, newbuffer, 0, bufsize - tokenBegin);
                buffer = newbuffer;

                System.arraycopy(bufline, tokenBegin, newbufline, 0, bufsize - tokenBegin);
                bufline = newbufline;

                System.arraycopy(bufcolumn, tokenBegin, newbufcolumn, 0, bufsize - tokenBegin);
                bufcolumn = newbufcolumn;

                bufpos -= tokenBegin;
            }
        } catch (Throwable t) {
            throw new Error(t.getMessage());
        }

        available = (bufsize += 2048);
        tokenBegin = 0;
    }

    private void FillBuff() throws java.io.IOException {
        int i;
        if (maxNextCharInd == 4096) {
            maxNextCharInd = nextCharInd = 0;
        }

        try {
            if ((i = inputStream.read(nextCharBuf, maxNextCharInd, 4096 - maxNextCharInd)) == -1) {
                inputStream.close();
                throw new java.io.IOException();
            } else {
                maxNextCharInd += i;
            }
            return;
        } catch (java.io.IOException e) {
            if (bufpos != 0) {
                --bufpos;
                backup(0);
            } else {
                bufline[bufpos] = line;
                bufcolumn[bufpos] = column;
            }
            throw e;
        }
    }

    private char readByte() throws java.io.IOException {
        if (++nextCharInd >= maxNextCharInd) {
            FillBuff();
        }

        return nextCharBuf[nextCharInd];
    }

    public char beginToken() throws java.io.IOException {
        if (inBuf > 0) {
            --inBuf;
            return buffer[tokenBegin = (bufpos == bufsize - 1) ? (bufpos = 0) : ++bufpos];
        }

        tokenBegin = 0;
        bufpos = -1;

        return readChar();
    }

    private void adjustBuffSize() {
        if (available == bufsize) {
            if (tokenBegin > 2048) {
                bufpos = 0;
                available = tokenBegin;
            } else {
                expandBuff(false);
            }
        } else if (available > tokenBegin) {
            available = bufsize;
        } else if ((tokenBegin - available) < 2048) {
            expandBuff(true);
        } else {
            available = tokenBegin;
        }
    }

    private void updateLineColumn(char c) {
        column++;

        if (prevCharIsLF) {
            prevCharIsLF = false;
            line += (column = 1);
        } else if (prevCharIsCR) {
            prevCharIsCR = false;
            if (c == '\n') {
                prevCharIsLF = true;
            } else {
                line += (column = 1);
            }
        }

        switch (c) {
        case '\r':
            prevCharIsCR = true;
            break;
        case '\n':
            prevCharIsLF = true;
            break;
        case '\t':
            column--;
            column += (8 - (column & 07));
            break;
        default:
            break;
        }

        bufline[bufpos] = line;
        bufcolumn[bufpos] = column;
    }

    public char readChar() throws java.io.IOException {
        if (inBuf > 0) {
            --inBuf;
            return buffer[(bufpos == bufsize - 1) ? (bufpos = 0) : ++bufpos];
        }

        char c;

        if (++bufpos == available) {
            adjustBuffSize();
        }

        if (((buffer[bufpos] = c = (char) ((char) 0xff & readByte())) == '\\')) {
            updateLineColumn(c);

            int backSlashCnt = 1;

            for (;;) // Read all the backslashes
            {
                if (++bufpos == available) {
                    adjustBuffSize();
                }

                try {
                    if ((buffer[bufpos] = c = (char) ((char) 0xff & readByte())) != '\\') {
                        updateLineColumn(c);
                        // found a non-backslash char.
                        if ((c == 'u') && ((backSlashCnt & 1) == 1)) {
                            if (--bufpos < 0) {
                                bufpos = bufsize - 1;
                            }

                            break;
                        }

                        backup(backSlashCnt);
                        return '\\';
                    }
                } catch (java.io.IOException e) {
                    if (backSlashCnt > 1) {
                        backup(backSlashCnt);
                    }

                    return '\\';
                }

                updateLineColumn(c);
                backSlashCnt++;
            }

            // Here, we have seen an odd number of backslash's followed by a 'u'
            try {
                while ((c = (char) ((char) 0xff & readByte())) == 'u') {
                    ++column;
                }

                buffer[bufpos] = c = (char) (hexval(c) << 12 | hexval((char) ((char) 0xff & readByte())) << 8 | hexval((char) ((char) 0xff & readByte())) << 4
                        | hexval((char) ((char) 0xff & readByte())));

                column += 4;
            } catch (java.io.IOException e) {
                throw new Error("Invalid escape character at line " + line + " column " + column + ".");
            }

            if (backSlashCnt == 1) {
                return c;
            } else {
                backup(backSlashCnt - 1);
                return '\\';
            }
        } else {
            updateLineColumn(c);
            return (c);
        }
    }

    public int getEndColumn() {
        return bufcolumn[bufpos];
    }

    public int getEndLine() {
        return bufline[bufpos];
    }

    public int getBeginColumn() {
        return bufcolumn[tokenBegin];
    }

    public int getBeginLine() {
        return bufline[tokenBegin];
    }

    public void backup(int amount) {

        inBuf += amount;
        if ((bufpos -= amount) < 0) {
            bufpos += bufsize;
        }
    }

    public ASCII_UCodeESC_CharStream(java.io.Reader dstream, int startline, int startcolumn, int buffersize) {
        inputStream = dstream;
        line = startline;
        column = startcolumn - 1;

        available = bufsize = buffersize;
        buffer = new char[buffersize];
        bufline = new int[buffersize];
        bufcolumn = new int[buffersize];
        nextCharBuf = new char[4096];
    }

    public ASCII_UCodeESC_CharStream(java.io.Reader dstream, int startline, int startcolumn) {
        this(dstream, startline, startcolumn, 4096);
    }

    public void reInit(java.io.Reader dstream, int startline, int startcolumn, int buffersize) {
        inputStream = dstream;
        line = startline;
        column = startcolumn - 1;

        if (buffer == null || buffersize != buffer.length) {
            available = bufsize = buffersize;
            buffer = new char[buffersize];
            bufline = new int[buffersize];
            bufcolumn = new int[buffersize];
            nextCharBuf = new char[4096];
        }
        prevCharIsLF = prevCharIsCR = false;
        tokenBegin = inBuf = maxNextCharInd = 0;
        nextCharInd = bufpos = -1;
    }

    public void reInit(java.io.Reader dstream, int startline, int startcolumn) {
        reInit(dstream, startline, startcolumn, 4096);
    }

    public ASCII_UCodeESC_CharStream(java.io.InputStream dstream, int startline, int startcolumn, int buffersize) {
        this(new java.io.InputStreamReader(dstream), startline, startcolumn, buffersize);
    }

    public ASCII_UCodeESC_CharStream(java.io.InputStream dstream, int startline, int startcolumn) {
        this(dstream, startline, startcolumn, 4096);
    }

    public void reInit(java.io.InputStream dstream, int startline, int startcolumn, int buffersize) {
        reInit(new java.io.InputStreamReader(dstream), startline, startcolumn, 4096);
    }

    public void reInit(java.io.InputStream dstream, int startline, int startcolumn) {
        reInit(dstream, startline, startcolumn, 4096);
    }

    public String GetImage() {
        if (bufpos >= tokenBegin) {
            return new String(buffer, tokenBegin, bufpos - tokenBegin + 1);
        } else {
            return new String(buffer, tokenBegin, bufsize - tokenBegin) + new String(buffer, 0, bufpos + 1);
        }
    }

    public char[] GetSuffix(int len) {
        char[] ret = new char[len];

        if ((bufpos + 1) >= len) {
            System.arraycopy(buffer, bufpos - len + 1, ret, 0, len);
        } else {
            System.arraycopy(buffer, bufsize - (len - bufpos - 1), ret, 0, len - bufpos - 1);
            System.arraycopy(buffer, 0, ret, len - bufpos - 1, bufpos + 1);
        }

        return ret;
    }

    public void Done() {
        nextCharBuf = null;
        buffer = null;
        bufline = null;
        bufcolumn = null;
    }

    /**
     * Method to adjust line and column numbers for the start of a token.<BR>
     */
    public void adjustBeginLineColumn(int newLine, int newCol) {
        int start = tokenBegin;
        int len;

        if (bufpos >= tokenBegin) {
            len = bufpos - tokenBegin + inBuf + 1;
        } else {
            len = bufsize - tokenBegin + bufpos + 1 + inBuf;
        }

        int i = 0, j = 0, k = 0;
        int nextColDiff = 0, columnDiff = 0;

        while (i < len && bufline[j = start % bufsize] == bufline[k = ++start % bufsize]) {
            bufline[j] = newLine;
            nextColDiff = columnDiff + bufcolumn[k] - bufcolumn[j];
            bufcolumn[j] = newCol + columnDiff;
            columnDiff = nextColDiff;
            i++;
        }

        if (i < len) {
            bufline[j] = newLine++;
            bufcolumn[j] = newCol + columnDiff;

            while (i++ < len) {
                if (bufline[j = start % bufsize] != bufline[++start % bufsize]) {
                    bufline[j] = newLine++;
                } else {
                    bufline[j] = newLine;
                }
            }
        }

        line = bufline[j];
        column = bufcolumn[j];
    }

}
