/*

 * Copyright (c) 2015, 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.LinkedHashSet;

import java.util.List;

import java.util.Set;

import java.util.stream.Stream;

import jdk.jshell.ClassTracker.ClassInfo;

import jdk.jshell.Snippet.Kind;

import jdk.jshell.Snippet.Status;

import jdk.jshell.Snippet.SubKind;

import jdk.jshell.TaskFactory.AnalyzeTask;

import jdk.jshell.TaskFactory.CompileTask;

import jdk.jshell.spi.ExecutionControl.ClassBytecodes;

import jdk.jshell.spi.ExecutionControl.ClassInstallException;

import jdk.jshell.spi.ExecutionControl.EngineTerminationException;

import jdk.jshell.spi.ExecutionControl.NotImplementedException;

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

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

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

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

import static jdk.jshell.Snippet.Status.OVERWRITTEN;

import static jdk.jshell.Snippet.Status.RECOVERABLE_DEFINED;

import static jdk.jshell.Snippet.Status.RECOVERABLE_NOT_DEFINED;

import static jdk.jshell.Snippet.Status.REJECTED;

import static jdk.jshell.Snippet.Status.VALID;

import static jdk.jshell.Util.PARSED_LOCALE;

import static jdk.jshell.Util.expunge;

/**

 * Tracks the compilation and load of a new or updated snippet.

 * @author Robert Field

 */

final class Unit {

    private final JShell state;

    private final Snippet si;

    private final Snippet siOld;

    private final boolean isDependency;

    private final boolean isNew;

    private final Snippet causalSnippet;

    private final DiagList generatedDiagnostics;

    private int seq;

    private String classNameInitial;

    private Wrap activeGuts;

    private Status status;

    private Status prevStatus;

    private boolean signatureChanged;

    private DiagList compilationDiagnostics;

    private DiagList recompilationDiagnostics = null;

    private List<String> unresolved;

    private SnippetEvent replaceOldEvent;

    private List<SnippetEvent> secondaryEvents;

    private boolean isAttemptingCorral;

    private List<ClassInfo> toRedefine;

    private boolean dependenciesNeeded;

    Unit(JShell state, Snippet si, Snippet causalSnippet,

            DiagList generatedDiagnostics) {

        this.state = state;

        this.si = si;

        this.isDependency = causalSnippet != null;

        this.siOld = isDependency

                ? si

                : state.maps.getSnippet(si.key());

        this.isNew = siOld == null;

        this.causalSnippet = causalSnippet;

        this.generatedDiagnostics = generatedDiagnostics;

        this.seq = isNew? 0 : siOld.sequenceNumber();

        this.classNameInitial = isNew? "<none>" : siOld.className();

        this.prevStatus = (isNew || isDependency)

                ? si.status()

                : siOld.status();

        si.setSequenceNumber(seq);

    }

    // Drop entry

    Unit(JShell state, Snippet si) {

        this.state = state;

        this.si = si;

        this.siOld = null;

        this.isDependency = false;

        this.isNew = false;

        this.causalSnippet = null;

        this.generatedDiagnostics = new DiagList();

        this.prevStatus = si.status();

        si.setDropped();

        this.status = si.status();

    }

    @Override

    public int hashCode() {

        return si.hashCode();

    }

    @Override

    public boolean equals(Object o) {

        return (o instanceof Unit)

                ? si.equals(((Unit) o).si)

                : false;

    }

    Snippet snippet() {

        return si;

    }

    boolean isDependency() {

        return isDependency;

    }

    void initialize() {

        isAttemptingCorral = false;

        dependenciesNeeded = false;

        toRedefine = null; // assure NPE if classToLoad not called

        activeGuts = si.guts();

        markOldDeclarationOverwritten();

    }

    // Set the outer wrap of our Snippet

    void setWrap(Collection<Unit> exceptUnit, Collection<Unit> plusUnfiltered) {

        if (isImport()) {

            si.setOuterWrap(state.outerMap.wrapImport(activeGuts, si));

        } else {

            // Collect Units for be wrapped together.  Just this except for overloaded methods

            List<Unit> units;

            if (snippet().kind() == Kind.METHOD) {

                String name = ((MethodSnippet) snippet()).name();

                units = plusUnfiltered.stream()

                        .filter(u -> u.snippet().kind() == Kind.METHOD &&

                                 ((MethodSnippet) u.snippet()).name().equals(name))

                        .collect(toList());

            } else {

                units = Collections.singletonList(this);

            }

            // Keys to exclude from imports

            Set<Key> except = exceptUnit.stream()

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

                    .collect(toSet());

            // Snippets to add to imports

            Collection<Snippet> plus = plusUnfiltered.stream()

                    .filter(u -> !units.contains(u))

                    .collect(toList());

            // Snippets to wrap in an outer

            List<Snippet> snippets = units.stream()

                    .collect(toList());

            // Snippet wraps to wrap in an outer

            List<Wrap> wraps = units.stream()

                    .map(u -> u.activeGuts)

                    .collect(toList());

            // Set the outer wrap for this snippet

            si.setOuterWrap(state.outerMap.wrapInClass(except, plus, snippets, wraps));

        }

    }

    void setDiagnostics(AnalyzeTask ct) {

        setDiagnostics(ct.getDiagnostics().ofUnit(this));

    }

    void setDiagnostics(DiagList diags) {

        compilationDiagnostics = diags;

        UnresolvedExtractor ue = new UnresolvedExtractor(diags);

        unresolved = ue.unresolved();

        state.debug(DBG_GEN, "++setCompilationInfo() %s\n%s\n-- diags: %s\n",

                si, si.outerWrap().wrapped(), diags);

    }

    private boolean isRecoverable() {

        // Unit failed, use corralling if it is defined on this Snippet,

        // and either all the errors are resolution errors or this is a

        // redeclare of an existing method

        return compilationDiagnostics.hasErrors()

                && si instanceof DeclarationSnippet

                && (isDependency()

                    || (si.subKind() != SubKind.VAR_DECLARATION_WITH_INITIALIZER_SUBKIND

                        && compilationDiagnostics.hasResolutionErrorsAndNoOthers()));

    }

    /**

     * If it meets the conditions for corralling, install the corralled wrap

     * @return true is the corralled wrap was installed

     */

    boolean corralIfNeeded(Collection<Unit> working) {

        if (isRecoverable()

                && si.corralled() != null) {

            activeGuts = si.corralled();

            setWrap(working, working);

            return isAttemptingCorral = true;

        }

        return isAttemptingCorral = false;

    }

    void setCorralledDiagnostics(AnalyzeTask cct) {

        // set corralled diagnostics, but don't reset unresolved

        recompilationDiagnostics = cct.getDiagnostics().ofUnit(this);

        state.debug(DBG_GEN, "++recomp %s\n%s\n-- diags: %s\n",

                si, si.outerWrap().wrapped(), recompilationDiagnostics);

    }

    boolean smashingErrorDiagnostics(CompileTask ct) {

        if (isDefined()) {

            // set corralled diagnostics, but don't reset unresolved

            DiagList dl = ct.getDiagnostics().ofUnit(this);

            if (dl.hasErrors()) {

                setDiagnostics(dl);

                status = RECOVERABLE_NOT_DEFINED;

                // overwrite orginal bytes

                state.debug(DBG_GEN, "++smashingErrorDiagnostics %s\n%s\n-- diags: %s\n",

                        si, si.outerWrap().wrapped(), dl);

                return true;

            }

        }

        return false;

    }

    void setStatus(AnalyzeTask at) {

        if (!compilationDiagnostics.hasErrors()) {

            status = VALID;

        } else if (isRecoverable()) {

            if (isAttemptingCorral && !recompilationDiagnostics.hasErrors()) {

                status = RECOVERABLE_DEFINED;

            } else {

                status = RECOVERABLE_NOT_DEFINED;

            }

        } else {

            status = REJECTED;

        }

        checkForOverwrite(at);

        state.debug(DBG_GEN, "setStatus() %s - status: %s\n",

                si, status);

    }

    boolean isDefined() {

        return status.isDefined();

    }

    /**

     * Process the class information from the last compile. Requires loading of

     * returned list.

     *

     * @return the list of classes to load

     */

    Stream<ClassBytecodes> classesToLoad(List<String> classnames) {

        toRedefine = new ArrayList<>();

        List<ClassBytecodes> toLoad = new ArrayList<>();

        if (status.isDefined() && !isImport()) {

            // Classes should only be loaded/redefined if the compile left them

            // in a defined state.  Imports do not have code and are not loaded.

            for (String cn : classnames) {

                ClassInfo ci = state.classTracker.get(cn);

                if (ci.isLoaded()) {

                    if (ci.isCurrent()) {

                        // nothing to do

                    } else {

                        toRedefine.add(ci);

                    }

                } else {

                    // If not loaded, add to the list of classes to load.

                    toLoad.add(ci.toClassBytecodes());

                    dependenciesNeeded = true;

                }

            }

        }

        return toLoad.stream();

    }

    /**

     * Redefine classes needing redefine. classesToLoad() must be called first.

     *

     * @return true if all redefines succeeded (can be vacuously true)

     */

    boolean doRedefines() {

        if (toRedefine.isEmpty()) {

            return true;

        }

        ClassBytecodes[] cbcs = toRedefine.stream()

        try {

            state.executionControl().redefine(cbcs);

            state.classTracker.markLoaded(cbcs);

            return true;

        } catch (ClassInstallException ex) {

            state.classTracker.markLoaded(cbcs, ex.installed());

            return false;

        } catch (EngineTerminationException ex) {

            state.closeDown();

            return false;

        } catch (NotImplementedException ex) {

            return false;

        }

    }

    void markForReplacement() {

        // increment for replace class wrapper

        si.setSequenceNumber(++seq);

    }

    private boolean isImport() {

        return si.kind() == Kind.IMPORT;

    }

    private boolean sigChanged() {

        return (status.isDefined() != prevStatus.isDefined())

                || (status.isDefined() && !si.className().equals(classNameInitial))

                || signatureChanged;

    }

    Stream<Unit> effectedDependents() {

        //System.err.printf("effectedDependents sigChanged=%b  dependenciesNeeded=%b   status=%s\n",

        //       sigChanged(), dependenciesNeeded, status);

        return sigChanged() || dependenciesNeeded || status == RECOVERABLE_NOT_DEFINED

                ? dependents()

                : Stream.empty();

    }

    Stream<Unit> dependents() {

        return state.maps.getDependents(si)

                    .stream()

                    .filter(xsi -> xsi != si && xsi.status().isActive())

                    .map(xsi -> new Unit(state, xsi, si, new DiagList()));

    }

    void finish() {

        recordCompilation();

        state.maps.installSnippet(si);

    }

    private void markOldDeclarationOverwritten() {

        if (si != siOld && siOld != null && siOld.status().isActive()) {

            // Mark the old declaraion as replaced

            replaceOldEvent = new SnippetEvent(siOld,

                    siOld.status(), OVERWRITTEN,

                    false, si, null, null);

            siOld.setOverwritten();

        }

    }

    private DiagList computeDiagnostics() {

        DiagList diagnostics = new DiagList();

        DiagList diags = compilationDiagnostics;

        if (status == RECOVERABLE_DEFINED || status == RECOVERABLE_NOT_DEFINED) {

            UnresolvedExtractor ue = new UnresolvedExtractor(diags);

            diagnostics.addAll(ue.otherAll());

        } else {

            unresolved = Collections.emptyList();

            diagnostics.addAll(diags);

        }

        diagnostics.addAll(generatedDiagnostics);

        return diagnostics;

    }

    private void recordCompilation() {

        state.maps.mapDependencies(si);

        DiagList diags = computeDiagnostics();

        si.setCompilationStatus(status, unresolved, diags);

        state.debug(DBG_GEN, "recordCompilation: %s -- status %s, unresolved %s\n",

                si, status, unresolved);

    }

    private void checkForOverwrite(AnalyzeTask at) {

        secondaryEvents = new ArrayList<>();

        if (replaceOldEvent != null) secondaryEvents.add(replaceOldEvent);

        // Defined methods can overwrite methods of other (equivalent) snippets

        if (isNew && si.kind() == Kind.METHOD && status.isDefined()) {

            MethodSnippet msi = (MethodSnippet)si;

            String oqpt = msi.qualifiedParameterTypes();

            String nqpt = computeQualifiedParameterTypes(at, msi);

            if (!nqpt.equals(oqpt)) {

                msi.setQualifiedParamaterTypes(nqpt);

                Status overwrittenStatus = overwriteMatchingMethod(msi);

                if (overwrittenStatus != null) {

                    prevStatus = overwrittenStatus;

                    signatureChanged = true;

                }

            }

        }

    }

    // Check if there is a method whose user-declared parameter types are

    // different (and thus has a different snippet) but whose compiled parameter

    // types are the same. if so, consider it an overwrite replacement.

    private Status overwriteMatchingMethod(MethodSnippet msi) {

        String qpt = msi.qualifiedParameterTypes();

        List<MethodSnippet> matching = state.methods()

                .filter(sn ->

                           sn != null

                        && sn != msi

                        && sn.status().isActive()

                        && sn.name().equals(msi.name())

                        && qpt.equals(sn.qualifiedParameterTypes()))

                .collect(toList());

        // Look through all methods for a method of the same name, with the

        // same computed qualified parameter types

        Status overwrittenStatus = null;

        for (MethodSnippet sn : matching) {

            overwrittenStatus = sn.status();

            SnippetEvent se = new SnippetEvent(

                    sn, overwrittenStatus, OVERWRITTEN,

                    false, msi, null, null);

            sn.setOverwritten();

            secondaryEvents.add(se);

            state.debug(DBG_EVNT,

                    "Overwrite event #%d -- key: %s before: %s status: %s sig: %b cause: %s\n",

                    secondaryEvents.size(), se.snippet(), se.previousStatus(),

                    se.status(), se.isSignatureChange(), se.causeSnippet());

        }

        return overwrittenStatus;

    }

    private String computeQualifiedParameterTypes(AnalyzeTask at, MethodSnippet msi) {

        String rawSig = TreeDissector.createBySnippet(at, msi).typeOfMethod(msi);

        String signature = expunge(rawSig);

        int paren = signature.lastIndexOf(')');

        // Extract the parameter type string from the method signature,

        // if method did not compile use the user-supplied parameter types

        return paren >= 0

                ? signature.substring(0, paren + 1)

                : msi.parameterTypes();

    }

    SnippetEvent event(String value, JShellException exception) {

        boolean wasSignatureChanged = sigChanged();

        state.debug(DBG_EVNT, "Snippet: %s id: %s before: %s status: %s sig: %b cause: %s\n",

                si, si.id(), prevStatus, si.status(), wasSignatureChanged, causalSnippet);

        return new SnippetEvent(si, prevStatus, si.status(),

                wasSignatureChanged, causalSnippet, value, exception);

    }

    List<SnippetEvent> secondaryEvents() {

        return secondaryEvents==null

                ? Collections.emptyList()

                : secondaryEvents;

    }

    @Override

    public String toString() {

        return "Unit(" + si.name() + ")";

    }

    /**

     * Separate out the unresolvedDependencies errors from both the other

     * corralling errors and the overall errors.

     */

    private static class UnresolvedExtractor {

        private static final String RESOLVE_ERROR_SYMBOL = "symbol:";

        private static final String RESOLVE_ERROR_LOCATION = "location:";

        //TODO extract from tree instead -- note: internationalization

        private final Set<String> unresolved = new LinkedHashSet<>();

        private final DiagList otherErrors = new DiagList();

        private final DiagList otherAll = new DiagList();

        UnresolvedExtractor(DiagList diags) {

            for (Diag diag : diags) {

                if (diag.isError()) {

                    if (diag.isResolutionError()) {

                        String m = diag.getMessage(PARSED_LOCALE);

                        int symPos = m.indexOf(RESOLVE_ERROR_SYMBOL);

                        if (symPos >= 0) {

                            m = m.substring(symPos + RESOLVE_ERROR_SYMBOL.length());

                            int symLoc = m.indexOf(RESOLVE_ERROR_LOCATION);

                            if (symLoc >= 0) {

                                m = m.substring(0, symLoc);

                            }

                            m = m.trim();

                            unresolved.add(m);

                            continue;

                        }

                    }

                    otherErrors.add(diag);

                }

                otherAll.add(diag);

            }

        }

        DiagList otherCorralledErrors() {

            return otherErrors;

        }