/*

 * Copyright (c) 2014, 2016, 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package jdk.jshell;

import java.util.ArrayList;

import java.util.Collection;

import java.util.Collections;

import java.util.List;

import java.util.Locale;

import java.util.regex.Matcher;

import java.util.regex.Pattern;

import java.util.stream.Collectors;

import javax.lang.model.element.Modifier;

import com.sun.source.tree.ArrayTypeTree;

import com.sun.source.tree.AssignmentTree;

import com.sun.source.tree.ClassTree;

import com.sun.source.tree.ExpressionTree;

import com.sun.source.tree.IdentifierTree;

import com.sun.source.tree.MethodTree;

import com.sun.source.tree.ModifiersTree;

import com.sun.source.tree.Tree;

import com.sun.source.tree.VariableTree;

import com.sun.tools.javac.tree.JCTree;

import com.sun.tools.javac.tree.Pretty;

import java.io.IOException;

import java.io.StringWriter;

import java.io.Writer;

import java.util.LinkedHashSet;

import java.util.Set;

import jdk.jshell.Key.ErroneousKey;

import jdk.jshell.Key.MethodKey;

import jdk.jshell.Key.TypeDeclKey;

import jdk.jshell.Snippet.SubKind;

import jdk.jshell.TaskFactory.AnalyzeTask;

import jdk.jshell.TaskFactory.BaseTask;

import jdk.jshell.TaskFactory.CompileTask;

import jdk.jshell.TaskFactory.ParseTask;

import jdk.jshell.TreeDissector.ExpressionInfo;

import jdk.jshell.Wrap.Range;

import jdk.jshell.Snippet.Status;

import static java.util.stream.Collectors.toList;

import static java.util.stream.Collectors.toSet;

import static jdk.internal.jshell.debug.InternalDebugControl.DBG_GEN;

import static jdk.jshell.Snippet.SubKind.SINGLE_TYPE_IMPORT_SUBKIND;

import static jdk.jshell.Snippet.SubKind.SINGLE_STATIC_IMPORT_SUBKIND;

import static jdk.jshell.Snippet.SubKind.TYPE_IMPORT_ON_DEMAND_SUBKIND;

import static jdk.jshell.Snippet.SubKind.STATIC_IMPORT_ON_DEMAND_SUBKIND;

/**

 * The Evaluation Engine. Source internal analysis, wrapping control,

 * compilation, declaration. redefinition, replacement, and execution.

 *

 * @author Robert Field

 */

class Eval {

    private static final Pattern IMPORT_PATTERN = Pattern.compile("import\\p{javaWhitespace}+(?<static>static\\p{javaWhitespace}+)?(?<fullname>[\\p{L}\\p{N}_\\$\\.]+\\.(?<name>[\\p{L}\\p{N}_\\$]+|\\*))");

    private int varNumber = 0;

    private final JShell state;

    Eval(JShell state) {

        this.state = state;

    }

    List<SnippetEvent> eval(String userSource) throws IllegalStateException {

        String compileSource = Util.trimEnd(new MaskCommentsAndModifiers(userSource, false).cleared());

        if (compileSource.length() == 0) {

            return Collections.emptyList();

        }

        // String folding messes up position information.

        ParseTask pt = state.taskFactory.new ParseTask(compileSource);

        if (pt.getDiagnostics().hasOtherThanNotStatementErrors()) {

            return compileFailResult(pt, userSource);

        }

        List<? extends Tree> units = pt.units();

        if (units.isEmpty()) {

            return compileFailResult(pt, userSource);

        }

        // Erase illegal modifiers

        compileSource = new MaskCommentsAndModifiers(compileSource, true).cleared();

        Tree unitTree = units.get(0);

        state.debug(DBG_GEN, "Kind: %s -- %s\n", unitTree.getKind(), unitTree);

        switch (unitTree.getKind()) {

            case IMPORT:

                return processImport(userSource, compileSource);

            case VARIABLE:

                return processVariables(userSource, units, compileSource, pt);

            case EXPRESSION_STATEMENT:

                return processExpression(userSource, compileSource);

            case CLASS:

                return processClass(userSource, unitTree, compileSource, SubKind.CLASS_SUBKIND, pt);

            case ENUM:

                return processClass(userSource, unitTree, compileSource, SubKind.ENUM_SUBKIND, pt);

            case ANNOTATION_TYPE:

                return processClass(userSource, unitTree, compileSource, SubKind.ANNOTATION_TYPE_SUBKIND, pt);

            case INTERFACE:

                return processClass(userSource, unitTree, compileSource, SubKind.INTERFACE_SUBKIND, pt);

            case METHOD:

                return processMethod(userSource, unitTree, compileSource, pt);

            default:

                return processStatement(userSource, compileSource);

        }

    }

    private List<SnippetEvent> processImport(String userSource, String compileSource) {

        Wrap guts = Wrap.simpleWrap(compileSource);

        Matcher mat = IMPORT_PATTERN.matcher(compileSource);

        String fullname;

        String name;

        boolean isStatic;

        if (mat.find()) {

            isStatic = mat.group("static") != null;

            name = mat.group("name");

            fullname = mat.group("fullname");

        } else {

            // bad import -- fake it

            isStatic = compileSource.contains("static");

            name = fullname = compileSource;

        }

        String fullkey = (isStatic ? "static-" : "") + fullname;

        boolean isStar = name.equals("*");

        String keyName = isStar

                ? fullname

                : name;

        SubKind snippetKind = isStar

                ? (isStatic ? STATIC_IMPORT_ON_DEMAND_SUBKIND : TYPE_IMPORT_ON_DEMAND_SUBKIND)

                : (isStatic ? SINGLE_STATIC_IMPORT_SUBKIND : SINGLE_TYPE_IMPORT_SUBKIND);

        Snippet snip = new ImportSnippet(state.keyMap.keyForImport(keyName, snippetKind),

                userSource, guts, fullname, name, snippetKind, fullkey, isStatic, isStar);

        return declare(snip);

    }

    private static class EvalPretty extends Pretty {

        private final Writer out;

        public EvalPretty(Writer writer, boolean bln) {

            super(writer, bln);

            this.out = writer;

        }

        /**

         * Print string, DO NOT replacing all non-ascii character with unicode

         * escapes.

         */

        @Override

        public void print(Object o) throws IOException {

            out.write(o.toString());

        }

        static String prettyExpr(JCTree tree, boolean bln) {

            StringWriter out = new StringWriter();

            try {

                new EvalPretty(out, bln).printExpr(tree);

            } catch (IOException e) {

                throw new AssertionError(e);

            }

            return out.toString();

        }

    }

    private List<SnippetEvent> processVariables(String userSource, List<? extends Tree> units, String compileSource, ParseTask pt) {

        List<SnippetEvent> allEvents = new ArrayList<>();

        TreeDissector dis = TreeDissector.createByFirstClass(pt);

        for (Tree unitTree : units) {

            VariableTree vt = (VariableTree) unitTree;

            String name = vt.getName().toString();

            String typeName = EvalPretty.prettyExpr((JCTree) vt.getType(), false);

            Tree baseType = vt.getType();

            TreeDependencyScanner tds = new TreeDependencyScanner();

            tds.scan(baseType); // Not dependent on initializer

            StringBuilder sbBrackets = new StringBuilder();

            while (baseType instanceof ArrayTypeTree) {

                //TODO handle annotations too

                baseType = ((ArrayTypeTree) baseType).getType();

                sbBrackets.append("[]");

            }

            Range rtype = dis.treeToRange(baseType);

            Range runit = dis.treeToRange(vt);

            runit = new Range(runit.begin, runit.end - 1);

            ExpressionTree it = vt.getInitializer();

            Range rinit = null;

            int nameMax = runit.end - 1;

            SubKind subkind;

            if (it != null) {

                subkind = SubKind.VAR_DECLARATION_WITH_INITIALIZER_SUBKIND;

                rinit = dis.treeToRange(it);

                nameMax = rinit.begin - 1;

            } else {

                subkind = SubKind.VAR_DECLARATION_SUBKIND;

            }

            int nameStart = compileSource.lastIndexOf(name, nameMax);

            if (nameStart < 0) {

                throw new AssertionError("Name '" + name + "' not found");

            }

            int nameEnd = nameStart + name.length();

            Range rname = new Range(nameStart, nameEnd);

            Wrap guts = Wrap.varWrap(compileSource, rtype, sbBrackets.toString(), rname, rinit);

            Snippet snip = new VarSnippet(state.keyMap.keyForVariable(name), userSource, guts,

                    name, subkind, typeName,

                    tds.declareReferences());

            DiagList modDiag = modifierDiagnostics(vt.getModifiers(), dis, true);

            List<SnippetEvent> res1 = declare(snip, modDiag);

            allEvents.addAll(res1);

        }

        return allEvents;

    }

    private List<SnippetEvent> processExpression(String userSource, String compileSource) {

        String name = null;

        ExpressionInfo ei = typeOfExpression(compileSource);

        ExpressionTree assignVar;

        Wrap guts;

        Snippet snip;

        if (ei != null && ei.isNonVoid) {

            String typeName = ei.typeName;

            SubKind subkind;

            if (ei.tree instanceof IdentifierTree) {

                IdentifierTree id = (IdentifierTree) ei.tree;

                name = id.getName().toString();

                subkind = SubKind.VAR_VALUE_SUBKIND;

            } else if (ei.tree instanceof AssignmentTree

                    && (assignVar = ((AssignmentTree) ei.tree).getVariable()) instanceof IdentifierTree) {

                name = assignVar.toString();

                subkind = SubKind.ASSIGNMENT_SUBKIND;

            } else {

                subkind = SubKind.OTHER_EXPRESSION_SUBKIND;

            }

            if (shouldGenTempVar(subkind)) {

                if (state.tempVariableNameGenerator != null) {

                    name = state.tempVariableNameGenerator.get();

                }

                while (name == null || state.keyMap.doesVariableNameExist(name)) {

                    name = "$" + ++varNumber;

                }

                guts = Wrap.tempVarWrap(compileSource, typeName, name);

                Collection<String> declareReferences = null; //TODO

                snip = new VarSnippet(state.keyMap.keyForVariable(name), userSource, guts,

                        name, SubKind.TEMP_VAR_EXPRESSION_SUBKIND, typeName, declareReferences);

            } else {

                guts = Wrap.methodReturnWrap(compileSource);

                snip = new ExpressionSnippet(state.keyMap.keyForExpression(name, typeName), userSource, guts,

                        name, subkind);

            }

        } else {

            guts = Wrap.methodWrap(compileSource);

            if (ei == null) {

                // We got no type info, check for not a statement by trying

                AnalyzeTask at = trialCompile(guts);

                if (at.getDiagnostics().hasNotStatement()) {

                    guts = Wrap.methodReturnWrap(compileSource);

                    at = trialCompile(guts);

                }

                if (at.hasErrors()) {

                    return compileFailResult(at, userSource);

                }

            }

            snip = new StatementSnippet(state.keyMap.keyForStatement(), userSource, guts);

        }

        return declare(snip);

    }

    private List<SnippetEvent> processClass(String userSource, Tree unitTree, String compileSource, SubKind snippetKind, ParseTask pt) {

        TreeDependencyScanner tds = new TreeDependencyScanner();

        tds.scan(unitTree);

        TreeDissector dis = TreeDissector.createByFirstClass(pt);

        ClassTree klassTree = (ClassTree) unitTree;

        String name = klassTree.getSimpleName().toString();

        DiagList modDiag = modifierDiagnostics(klassTree.getModifiers(), dis, false);

        TypeDeclKey key = state.keyMap.keyForClass(name);

        // Corralling mutates.  Must be last use of pt, unitTree, klassTree

        Wrap corralled = new Corraller(key.index(), pt.getContext()).corralType(klassTree);

        Wrap guts = Wrap.classMemberWrap(compileSource);

        Snippet snip = new TypeDeclSnippet(key, userSource, guts,

                name, snippetKind,

                corralled, tds.declareReferences(), tds.bodyReferences());

        return declare(snip, modDiag);

    }

    private List<SnippetEvent> processStatement(String userSource, String compileSource) {

        Wrap guts = Wrap.methodWrap(compileSource);

        // Check for unreachable by trying

        AnalyzeTask at = trialCompile(guts);

        if (at.hasErrors()) {

            if (at.getDiagnostics().hasUnreachableError()) {

                guts = Wrap.methodUnreachableSemiWrap(compileSource);

                at = trialCompile(guts);

                if (at.hasErrors()) {

                    if (at.getDiagnostics().hasUnreachableError()) {

                        // Without ending semicolon

                        guts = Wrap.methodUnreachableWrap(compileSource);

                        at = trialCompile(guts);

                    }

                    if (at.hasErrors()) {

                        return compileFailResult(at, userSource);

                    }

                }

            } else {

                return compileFailResult(at, userSource);

            }

        }

        Snippet snip = new StatementSnippet(state.keyMap.keyForStatement(), userSource, guts);

        return declare(snip);

    }

    private AnalyzeTask trialCompile(Wrap guts) {

        OuterWrap outer = state.outerMap.wrapInTrialClass(guts);

        return state.taskFactory.new AnalyzeTask(outer);

    }

    private List<SnippetEvent> processMethod(String userSource, Tree unitTree, String compileSource, ParseTask pt) {

        TreeDependencyScanner tds = new TreeDependencyScanner();

        tds.scan(unitTree);

        TreeDissector dis = TreeDissector.createByFirstClass(pt);

        MethodTree mt = (MethodTree) unitTree;

        String name = mt.getName().toString();

        String parameterTypes

                = mt.getParameters()

                .stream()

                .map(param -> dis.treeToRange(param.getType()).part(compileSource))

                .collect(Collectors.joining(","));

        Tree returnType = mt.getReturnType();

        DiagList modDiag = modifierDiagnostics(mt.getModifiers(), dis, true);

        MethodKey key = state.keyMap.keyForMethod(name, parameterTypes);

        // Corralling mutates.  Must be last use of pt, unitTree, mt

        Wrap corralled = new Corraller(key.index(), pt.getContext()).corralMethod(mt);

        if (modDiag.hasErrors()) {

            return compileFailResult(modDiag, userSource);

        }

        Wrap guts = Wrap.classMemberWrap(compileSource);

        Range typeRange = dis.treeToRange(returnType);

        String signature = "(" + parameterTypes + ")" + typeRange.part(compileSource);

        Snippet snip = new MethodSnippet(key, userSource, guts,

                name, signature,

                corralled, tds.declareReferences(), tds.bodyReferences());

        return declare(snip, modDiag);

    }

    /**

     * The snippet has failed, return with the rejected event

     *

     * @param xt the task from which to extract the failure diagnostics

     * @param userSource the incoming bad user source

     * @return a rejected snippet event

     */

    private List<SnippetEvent> compileFailResult(BaseTask xt, String userSource) {

        return compileFailResult(xt.getDiagnostics(), userSource);

    }

    /**

     * The snippet has failed, return with the rejected event

     *

     * @param diags the failure diagnostics

     * @param userSource the incoming bad user source

     * @return a rejected snippet event

     */

    private List<SnippetEvent> compileFailResult(DiagList diags, String userSource) {

        ErroneousKey key = state.keyMap.keyForErroneous();

        Snippet snip = new ErroneousSnippet(key, userSource, null, SubKind.UNKNOWN_SUBKIND);

        snip.setFailed(diags);

        state.maps.installSnippet(snip);

        return Collections.singletonList(new SnippetEvent(

                snip, Status.NONEXISTENT, Status.REJECTED,

                false, null, null, null)

        );

    }

    private ExpressionInfo typeOfExpression(String expression) {

        Wrap guts = Wrap.methodReturnWrap(expression);

        TaskFactory.AnalyzeTask at = trialCompile(guts);

        if (!at.hasErrors() && at.firstCuTree() != null) {

            return TreeDissector.createByFirstClass(at)

                    .typeOfReturnStatement(at, state);

        }

        return null;

    }

    /**

     * Should a temp var wrap the expression. TODO make this user configurable.

     *

     * @param snippetKind

     * @return

     */

    private boolean shouldGenTempVar(SubKind snippetKind) {

        return snippetKind == SubKind.OTHER_EXPRESSION_SUBKIND;

    }

    List<SnippetEvent> drop(Snippet si) {

        Unit c = new Unit(state, si);

        Set<Unit> ins = c.dependents().collect(toSet());

        Set<Unit> outs = compileAndLoad(ins);

        return events(c, outs, null, null);

    }

    private List<SnippetEvent> declare(Snippet si) {

        return declare(si, new DiagList());

    }

    private List<SnippetEvent> declare(Snippet si, DiagList generatedDiagnostics) {

        Unit c = new Unit(state, si, null, generatedDiagnostics);

        Set<Unit> ins = new LinkedHashSet<>();

        ins.add(c);

        Set<Unit> outs = compileAndLoad(ins);

        if (!si.status().isDefined

                && si.diagnostics().isEmpty()

                && si.unresolved().isEmpty()) {

            // did not succeed, but no record of it, extract from others

            si.setDiagnostics(outs.stream()

                    .flatMap(u -> u.snippet().diagnostics().stream())

                    .collect(Collectors.toCollection(DiagList::new)));

        }

        // If appropriate, execute the snippet

        String value = null;

        JShellException exception = null;

        if (si.status().isDefined) {

            if (si.isExecutable()) {

                try {

                    value = si.subKind().hasValue()

                            ? expunge(value)

                            : "";

                } catch (EvalException ex) {

                    exception = translateExecutionException(ex);

                } catch (JShellException ex) {

                    // UnresolvedReferenceException

                    exception = ex;

                }

            } else if (si.subKind() == SubKind.VAR_DECLARATION_SUBKIND) {

                switch (((VarSnippet) si).typeName()) {

                    case "byte":

                    case "short":

                    case "int":

                    case "long":

                        value = "0";

                        break;

                    case "float":

                    case "double":

                        value = "0.0";

                        break;

                    case "boolean":

                        value = "false";

                        break;

                    case "char":

                        value = "''";

                        break;

                    default:

                        value = "null";

                        break;

                }

            }

        }

        return events(c, outs, value, exception);

    }

    private boolean interestingEvent(SnippetEvent e) {

        return e.isSignatureChange()

                    || e.causeSnippet() == null

                    || e.status() != e.previousStatus()

                    || e.exception() != null;

    }

    private List<SnippetEvent> events(Unit c, Collection<Unit> outs, String value, JShellException exception) {

        List<SnippetEvent> events = new ArrayList<>();

        events.add(c.event(value, exception));

        events.addAll(outs.stream()

                .filter(u -> u != c)

                .map(u -> u.event(null, null))

                .filter(this::interestingEvent)

                .collect(Collectors.toList()));

        events.addAll(outs.stream()

                .flatMap(u -> u.secondaryEvents().stream())

                .filter(this::interestingEvent)

                .collect(Collectors.toList()));

        //System.err.printf("Events: %s\n", events);

        return events;

    }

    private Set<OuterWrap> outerWrapSet(Collection<Unit> units) {

        return units.stream()

                .map(u -> u.snippet().outerWrap())