/*
 * Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * questions.
 */

package jdk.jshell;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import static java.util.stream.Collectors.joining;
import static jdk.jshell.Util.DOIT_METHOD_NAME;

Wrapping of source into Java methods, fields, etc.  All but outer layer
wrapping with imports and class.
/**
 * Wrapping of source into Java methods, fields, etc.  All but outer layer
 * wrapping with imports and class.
 */
abstract class Wrap implements GeneralWrap {

    private static Wrap methodWrap(String prefix, String source, String suffix) {
        Wrap wunit = new NoWrap(source);
        return new DoitMethodWrap(new CompoundWrap(prefix, wunit, suffix));
    }

    public static Wrap methodWrap(String source) {
        return methodWrap("", source, semi(source) + "        return null;\n");
    }

    public static Wrap methodReturnWrap(String source) {
        return methodWrap("return ", source, semi(source));
    }

    public static Wrap methodUnreachableSemiWrap(String source) {
        return methodWrap("", source, semi(source));
    }

    public static Wrap methodUnreachableWrap(String source) {
        return methodWrap("", source, "");
    }

    private static String indent(int n) {
        return "                              ".substring(0, n * 4);
    }

    private static String nlindent(int n) {
        return "\n" + indent(n);
    }

    
Create a stub of a compilable representation of a variable snippet. The variable is always represented by a field. If the variable in the snippet has an initializer, the field is initialized by calling the DOIT_METHOD_NAME method. In some cases, the real inferred type of the variable may be non-denotable (e.g. intersection types). The declared type of the field must always be denotable (i.e. such that it can be written into the classfile), but if the real type is potentially non-denotable, the enhanced parameter must be true. 
Params:
source – the snippet's masked source code
wtype – variable's denotable type suitable for field declaration
brackets – any [] that should be appended to the type
wname – a wrap of the source that denotes the name of the variable
winit – Initializer or null
enhanced – if the real inferred type of the variable is potentially
                non-denotable, this must be true
Returns:
a Wrap that declares the given variable, potentially with
        an initialization method/**Create a stub of a compilable representation of a variable snippet.
     * The variable is always represented by a field. If the variable
     * in the snippet has an initializer, the field is initialized by
     * calling the DOIT_METHOD_NAME method.
     *
     * In some cases, the real inferred type of the variable may be non-denotable
     * (e.g. intersection types). The declared type of the field must always
     * be denotable (i.e. such that it can be written into the classfile), but
     * if the real type is potentially non-denotable, the {@code enhanced} parameter
     * must be true.
     *
     * @param source the snippet's masked source code
     * @param wtype variable's denotable type suitable for field declaration
     * @param brackets any [] that should be appended to the type
     * @param wname a wrap of the source that denotes the name of the variable
     * @param winit Initializer or null
     * @param enhanced if the real inferred type of the variable is potentially
     *                 non-denotable, this must be true
     * @return a Wrap that declares the given variable, potentially with
     *         an initialization method
     */
    public static Wrap varWrap(String source, Wrap wtype, String brackets,
                               Wrap wname, Wrap winit, boolean enhanced,
                               Wrap anonDeclareWrap) {
        List<Object> components = new ArrayList<>();
        components.add(new VarDeclareWrap(wtype, brackets, wname));
        Wrap wmeth;

        if (winit == null) {
            wmeth = new CompoundWrap(new NoWrap(" "), "   return null;\n");
        } else {
            // int x = y
            if (enhanced) {
                // private static <Z> Z do_itAux() {
                //     wtype x_ = y;
                //     @SuppressWarnings("unchecked")
                //     Z x__ = (Z) x_;
                //     return x__;
                // }
                // in do_it method:
                //return do_itAux();
                //find an unused name:
                String scratchName = "$";
                while (winit.wrapped().contains(scratchName)) {
                    scratchName += "$";
                }
                Wrap waux = new CompoundWrap(
                        "    private static <" + scratchName + "> " + scratchName +" ", DOIT_METHOD_NAME + "Aux", "() throws Throwable {\n",
                        wtype, brackets + " ", scratchName, "_ =\n        ", winit, semi(winit),
                        "        @SuppressWarnings(\"unchecked\") ", scratchName, " ", scratchName, "__ = (", scratchName, ")", scratchName, "_;\n",
                        "        return ", scratchName, "__;\n",
                        "}"
                );
                components.add(waux);
                wmeth = new CompoundWrap(
                        "        return ", wname, " = ", DOIT_METHOD_NAME + "Aux", "();\n"
                );
            } else {
                // int x_ = y; return x = x_;
                // decl + "_ = " + init ; + "return " + name + "= " + name + "_ ;"
                wmeth = new CompoundWrap(
                        wtype, brackets + " ", wname, "_ =\n        ", winit, semi(winit),
                        "        return ", wname, " = ", wname, "_;\n"
                );
            }
        }
        components.add(new DoitMethodWrap(wmeth));
        if (anonDeclareWrap != null) {
            components.add(anonDeclareWrap);
        }
        return new CompoundWrap(components.toArray());
    }

    public static Wrap tempVarWrap(String source, String typename, String name, Wrap anonDeclareWrap) {
        RangeWrap winit = new NoWrap(source);
        // y
        // return $1 = y;
        // "return " + $1 + "=" + init ;
        Wrap wmeth = new CompoundWrap("return " + name + " =\n        ", winit, semi(winit));
        Wrap wInitMeth = new DoitMethodWrap(wmeth);

        String varDecl = "    public static\n    " + typename + " " + name + ";\n";
        return anonDeclareWrap != null ? new CompoundWrap(varDecl, wInitMeth, anonDeclareWrap)
                                       : new CompoundWrap(varDecl, wInitMeth);
    }

    public static Wrap simpleWrap(String source) {
        return new NoWrap(source);
    }

    public static Wrap identityWrap(String source) {
        return new NoWrap(source);
    }

    public static Wrap rangeWrap(String source, Range range) {
        return new RangeWrap(source, range);
    }

    public static Wrap classMemberWrap(String source) {
        Wrap w = new NoWrap(source);
        return new CompoundWrap("    public static\n    ", w);
    }

    private static int countLines(String s) {
        return countLines(s, 0, s.length());
    }

    private static int countLines(String s, int from, int toEx) {
        int cnt = 0;
        int idx = from;
        while ((idx = s.indexOf('\n', idx)) > 0) {
            if (idx >= toEx) break;
            ++cnt;
            ++idx;
        }
        return cnt;
    }

    public static final class Range {
        final int begin;
        final int end; // exclusive

        Range(int begin, int end) {
            this.begin = begin;
            this.end = end;
        }

        Range(String s) {
            this.begin = 0;
            this.end = s.length();
        }

        String part(String s) {
            return s.substring(begin, end);
        }

        int length() {
            return end - begin;
        }

        boolean isEmpty() {
            return end == begin;
        }

        void verify(String s) {
            if (begin < 0 || end <= begin || end > s.length()) {
                throw new InternalError("Bad Range: " + s + "[" + begin + "," + end + "]");
            }
        }

        @Override
        public String toString() {
            return "Range[" + begin + "," + end + ")";
        }
    }

    public static class CompoundWrap extends Wrap {

        final Object[] os;
        final String wrapped;
        final int snidxFirst;
        final int snidxLast;
        final int snlineFirst;
        final int snlineLast;

        CompoundWrap(Object... os) {
            this.os = os;
            int sniFirst = Integer.MAX_VALUE;
            int sniLast = Integer.MIN_VALUE;
            int snlnFirst = Integer.MAX_VALUE;
            int snlnLast = Integer.MIN_VALUE;
            StringBuilder sb = new StringBuilder();
            for (Object o : os) {
                if (o instanceof String) {
                    String s = (String) o;
                    sb.append(s);
                } else if (o instanceof Wrap) {
                    Wrap w = (Wrap) o;
                    if (w.firstSnippetIndex() < sniFirst) {
                        sniFirst = w.firstSnippetIndex();
                    }
                    if (w.lastSnippetIndex() > sniLast) {
                        sniLast = w.lastSnippetIndex();
                    }
                    if (w.firstSnippetLine() < snlnFirst) {
                        snlnFirst = w.firstSnippetLine();
                    }
                    if (w.lastSnippetLine() > snlnLast) {
                        snlnLast = w.lastSnippetLine();
                    }
                    sb.append(w.wrapped());
                } else {
                    throw new InternalError("Bad object in CommoundWrap: " + o);
                }
            }
            this.wrapped = sb.toString();
            this.snidxFirst = sniFirst;
            this.snidxLast = sniLast;
            this.snlineFirst = snlnFirst;
            this.snlineLast = snlnLast;
        }

        @Override
        public String wrapped() {
            return wrapped;
        }

        @Override
        public int snippetIndexToWrapIndex(int sni) {
            int before = 0;
            for (Object o : os) {
                if (o instanceof String) {
                    String s = (String) o;
                    before += s.length();
                } else if (o instanceof Wrap) {
                    Wrap w = (Wrap) o;
                    if (sni >= w.firstSnippetIndex() && sni < w.lastSnippetIndex()) {
                        int wwi = w.snippetIndexToWrapIndex(sni);
                        debugWrap("\nCommoundWrap.snippetIndexToWrapIndex: SnippetIndex(%d) -> WrapIndex(%d + %d = %d)"
                                        + "\n   === %s",
                                sni, wwi, before, wwi + before, wrapped());
                        return wwi + before;
                    }
                    before += w.wrapped().length();
                }
            }
            return 0;
        }

        Wrap wrapIndexToWrap(long wi) {
            int before = 0;
            Wrap w = null;
            for (Object o : os) {
                if (o instanceof String) {
                    String s = (String) o;
                    before += s.length();
                } else if (o instanceof Wrap) {
                    w = (Wrap) o;
                    int len = w.wrapped().length();
                    if ((wi - before) <= len) {
                        debugWrap("CommoundWrap.wrapIndexToWrap: Defer to wrap %s - wi: %d. before; %d   >>> %s\n",
                                w, wi, before, w.wrapped());
                        return w;
                    }
                    before += len;
                }
            }
            return w;
        }

        @Override
        public int wrapIndexToSnippetIndex(int wi) {
            int before = 0;
            for (Object o : os) {
                if (o instanceof String) {
                    String s = (String) o;
                    before += s.length();
                } else if (o instanceof Wrap) {
                    Wrap w = (Wrap) o;
                    int len = w.wrapped().length();
                    if ((wi - before) <= len) {
                        int si = w.wrapIndexToSnippetIndex(wi - before);
                        debugWrap("\nCommoundWrap.wrapIndexToSnippetIndex: WrapIndex(%d) -> SnippetIndex(%d)\n",
                                wi, si);
                        return si;
                    }
                    before += len;
                }
            }
            return lastSnippetIndex();
        }

        @Override
        public int firstSnippetIndex() {
            return snidxFirst;
        }

        @Override
        public int lastSnippetIndex() {
            return snidxLast;
        }

        @Override
        public int snippetLineToWrapLine(int snline) {
            int before = 0;
            for (Object o : os) {
                if (o instanceof String) {
                    String s = (String) o;
                    before += countLines(s);
                } else if (o instanceof Wrap) {
                    Wrap w = (Wrap) o;
                    if (snline >= w.firstSnippetLine() && snline <= w.lastSnippetLine()) {
                        return w.snippetLineToWrapLine(snline) + before;
                    }
                    before += countLines(w.wrapped());
                }
            }
            return 0;
        }

        Wrap wrapLineToWrap(int wline) {
            int before = 0;
            Wrap w = null;
            for (Object o : os) {
                if (o instanceof String) {
                    String s = (String) o;
                    before += countLines(s);
                } else if (o instanceof Wrap) {
                    w = (Wrap) o;
                    int lns = countLines(w.wrapped());
                    if ((wline - before) <= lns) {
                        return w;
                    }
                    before += lns;
                }
            }
            return w;
        }

        @Override
        public int wrapLineToSnippetLine(int wline) {
            int before = 0;
            for (Object o : os) {
                if (o instanceof String) {
                    String s = (String) o;
                    before += countLines(s);
                } else if (o instanceof Wrap) {
                    Wrap w = (Wrap) o;
                    int lns = countLines(w.wrapped());
                    if ((wline - before) <= lns) {
                        return w.wrapLineToSnippetLine(wline - before);
                    }
                    before += lns;
                }
            }
            return 0;
        }

        @Override
        public int firstSnippetLine() {
            return snlineFirst;
        }

        @Override
        public int lastSnippetLine() {
            return snlineLast;
        }

        @Override
        public String toString() {
            return "CompoundWrap(" + Arrays.stream(os)
                    .map(o -> (o instanceof String)
                            ? "\"" + o + "\""
                            : o.toString())
                    .collect(joining(","))
                    + ")";
        }
    }

    static class RangeWrap extends Wrap {

        final Range range;
        final String wrapped;   // The snippet portion of the source
        final int firstSnline;  // Line count to start of snippet portion
        final int lastSnline;   // Line count to end of snippet portion

        RangeWrap(String snippetSource, Range usedWithinSnippet) {
            this.range = usedWithinSnippet;
            this.wrapped = usedWithinSnippet.part(snippetSource);
            usedWithinSnippet.verify(snippetSource);
            this.firstSnline = countLines(snippetSource, 0, range.begin);
            this.lastSnline = firstSnline + countLines(snippetSource, range.begin, range.end);
        }

        @Override
        public String wrapped() {
            return wrapped;
        }

        @Override
        public int snippetIndexToWrapIndex(int sni) {
            if (sni < range.begin) {
                debugWrap("\nRangeWrap.snippetIndexToWrapIndex: ERR before SnippetIndex(%d) -> WrapIndex(%d + %d = %d)\n",
                        sni, 0);
                return 0;
            }
            if (sni > range.end) {
                debugWrap("\nRangeWrap.snippetIndexToWrapIndex: ERR after SnippetIndex(%d) -> WrapIndex(%d + %d = %d)\n",
                        sni, range.length());
                return range.length();
            }
            int wi = sni - range.begin;
            debugWrap("\nRangeWrap.snippetIndexToWrapIndex: SnippetIndex(%d) -> WrapIndex(%d + %d = %d)"
                            + "\n   === %s",
                    sni, sni, range.begin, sni - range.begin, wrapped());
            return wi;
        }

        @Override
        public int wrapIndexToSnippetIndex(int wi) {
            if (wi < 0) {
                debugWrap("\nRangeWrap.wrapIndexToSnippetIndex: ERR before WrapIndex(%d) -> SnippetIndex(%d)\n",
                        wi, 0);
                return 0; // bad index
            }
            int max = range.length();
            if (wi > max) {
                debugWrap("\nRangeWrap.wrapIndexToSnippetIndex: ERR after WrapIndex(%d) -> SnippetIndex(%d)\n",
                        wi, max + range.begin);
                return max + range.begin;
            }
            int sni = wi + range.begin;
            debugWrap("\nRangeWrap.wrapIndexToSnippetIndex: WrapIndex(%d) -> SnippetIndex(%d)\n",
                    wi, sni);
            return sni;
        }

        @Override
        public int firstSnippetIndex() {
            return range.begin;
        }

        @Override
        public int lastSnippetIndex() {
            return range.end;
        }

        @Override
        public int snippetLineToWrapLine(int snline) {
            if (snline < firstSnline) {
                return 0;
            }
            if (snline >= lastSnline) {
                return lastSnline - firstSnline;
            }
            return snline - firstSnline;
        }

        @Override
        public int wrapLineToSnippetLine(int wline) {
            if (wline < 0) {
                return 0; // bad index
            }
            int max = lastSnline - firstSnline;
            if (wline > max) {
                wline = max;
            }
            return wline + firstSnline;
        }

        @Override
        public int firstSnippetLine() {
            return firstSnline;
        }

        @Override
        public int lastSnippetLine() {
            return lastSnline;
        }

        @Override
        public String toString() {
            return "RangeWrap(" + range + ")";
        }
    }

    private static class NoWrap extends RangeWrap {

        NoWrap(String unit) {
            super(unit, new Range(unit));
        }
    }

    private static String semi(Wrap w) {
        return semi(w.wrapped());
    }

    private static String semi(String s) {
        return ((s.endsWith(";")) ? "\n" : ((s.endsWith(";\n")) ? "" : ";\n"));
    }

    private static class DoitMethodWrap extends CompoundWrap {

        DoitMethodWrap(Wrap w) {
            super("    public static Object " + DOIT_METHOD_NAME + "() throws Throwable {\n"
                    + "        ", w,
                    "    }\n");
        }
    }

    private static class VarDeclareWrap extends CompoundWrap {

        VarDeclareWrap(Wrap wtype, String brackets, Wrap wname) {
            super("    public static ", wtype, brackets + " ", wname, semi(wname));
        }
    }

    void debugWrap(String format, Object... args) {
        //System.err.printf(format, args);
        //state.debug(this, InternalDebugControl.DBG_WRAP, format, args);
    }
}