/*
 * Copyright (c) 2015, 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.internal.jshell.tool;

import jdk.jshell.SourceCodeAnalysis.CompletionInfo;
import jdk.jshell.SourceCodeAnalysis.QualifiedNames;
import jdk.jshell.SourceCodeAnalysis.Suggestion;

import java.awt.event.ActionListener;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintStream;
import java.io.UncheckedIOException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Objects;
import java.util.Optional;
import java.util.function.Supplier;

import jdk.internal.jline.NoInterruptUnixTerminal;
import jdk.internal.jline.Terminal;
import jdk.internal.jline.TerminalFactory;
import jdk.internal.jline.UnsupportedTerminal;
import jdk.internal.jline.WindowsTerminal;
import jdk.internal.jline.console.ConsoleReader;
import jdk.internal.jline.console.KeyMap;
import jdk.internal.jline.console.UserInterruptException;
import jdk.internal.jline.console.completer.Completer;
import jdk.internal.jshell.tool.StopDetectingInputStream.State;

class ConsoleIOContext extends IOContext {

    final JShellTool repl;
    final StopDetectingInputStream input;
    final ConsoleReader in;
    final EditingHistory history;

    String prefix = "";

    ConsoleIOContext(JShellTool repl, InputStream cmdin, PrintStream cmdout) throws Exception {
        this.repl = repl;
        this.input = new StopDetectingInputStream(() -> repl.state.stop(), ex -> repl.hard("Error on input: %s", ex));
        Terminal term;
        if (System.getProperty("test.jdk") != null) {
            term = new UnsupportedTerminal();
        } else if (System.getProperty("os.name").toLowerCase(Locale.US).contains(TerminalFactory.WINDOWS)) {
            term = new JShellWindowsTerminal(input);
        } else {
            term = new JShellUnixTerminal(input);
        }
        term.init();
        in = new ConsoleReader(cmdin, cmdout, term);
        in.setExpandEvents(false);
        in.setHandleUserInterrupt(true);
        in.setHistory(history = new EditingHistory(JShellTool.PREFS) {
            @Override protected CompletionInfo analyzeCompletion(String input) {
                return repl.analysis.analyzeCompletion(input);
            }
        });
        in.setBellEnabled(true);
        in.addCompleter(new Completer() {
            private String lastTest;
            private int lastCursor;
            private boolean allowSmart = false;
            @Override public int complete(String test, int cursor, List<CharSequence> result) {
                int[] anchor = new int[] {-1};
                List<Suggestion> suggestions;
                if (prefix.isEmpty() && test.trim().startsWith("/")) {
                    suggestions = repl.commandCompletionSuggestions(test, cursor, anchor);
                } else {
                    int prefixLength = prefix.length();
                    suggestions = repl.analysis.completionSuggestions(prefix + test, cursor + prefixLength, anchor);
                    anchor[0] -= prefixLength;
                }
                if (!Objects.equals(lastTest, test) || lastCursor != cursor)
                    allowSmart = true;

                boolean smart = allowSmart &&
                                suggestions.stream()
                                           .anyMatch(s -> s.isSmart);

                lastTest = test;
                lastCursor = cursor;
                allowSmart = !allowSmart;

                suggestions.stream()
                           .filter(s -> !smart || s.isSmart)
                           .map(s -> s.continuation)
                           .forEach(result::add);

                boolean onlySmart = suggestions.stream()
                                               .allMatch(s -> s.isSmart);

                if (smart && !onlySmart) {
                    Optional<String> prefix =
                            suggestions.stream()
                                       .map(s -> s.continuation)
                                       .reduce(ConsoleIOContext::commonPrefix);

                    String prefixStr = prefix.orElse("").substring(cursor - anchor[0]);
                    try {
                        in.putString(prefixStr);
                        cursor += prefixStr.length();
                    } catch (IOException ex) {
                        throw new IllegalStateException(ex);
                    }
                    result.add("<press tab to see more>");
                    return cursor; //anchor should not be used.
                }

                if (result.isEmpty()) {
                    try {
                        //provide "empty completion" feedback
                        //XXX: this only works correctly when there is only one Completer:
                        in.beep();
                    } catch (IOException ex) {
                        throw new UncheckedIOException(ex);
                    }
                }

                return anchor[0];
            }
        });
        bind(DOCUMENTATION_SHORTCUT, (ActionListener) evt -> documentation(repl));
        bind(CTRL_UP, (ActionListener) evt -> moveHistoryToSnippet(((EditingHistory) in.getHistory())::previousSnippet));
        bind(CTRL_DOWN, (ActionListener) evt -> moveHistoryToSnippet(((EditingHistory) in.getHistory())::nextSnippet));
        for (FixComputer computer : FIX_COMPUTERS) {
            for (String shortcuts : SHORTCUT_FIXES) {
                bind(shortcuts + computer.shortcut, (ActionListener) evt -> fixes(computer));
            }
        }
    }

    @Override
    public String readLine(String prompt, String prefix) throws IOException, InputInterruptedException {
        this.prefix = prefix;
        try {
            return in.readLine(prompt);
        } catch (UserInterruptException ex) {
            throw (InputInterruptedException) new InputInterruptedException().initCause(ex);
        }
    }

    @Override
    public boolean interactiveOutput() {
        return true;
    }

    @Override
    public Iterable<String> currentSessionHistory() {
        return history.currentSessionEntries();
    }

    @Override
    public void close() throws IOException {
        history.save();
        in.shutdown();
        try {
            in.getTerminal().restore();
        } catch (Exception ex) {
            throw new IOException(ex);
        }
    }

    private void moveHistoryToSnippet(Supplier<Boolean> action) {
        if (!action.get()) {
            try {
                in.beep();
            } catch (IOException ex) {
                throw new IllegalStateException(ex);
            }
        } else {
            try {
                //could use:
                //in.resetPromptLine(in.getPrompt(), in.getHistory().current().toString(), -1);
                //but that would mean more re-writing on the screen, (and prints an additional
                //empty line), so using setBuffer directly:
                Method setBuffer = in.getClass().getDeclaredMethod("setBuffer", String.class);

                setBuffer.setAccessible(true);
                setBuffer.invoke(in, in.getHistory().current().toString());
                in.flush();
            } catch (ReflectiveOperationException | IOException ex) {
                throw new IllegalStateException(ex);
            }
        }
    }

    private void bind(String shortcut, Object action) {
        KeyMap km = in.getKeys();
        for (int i = 0; i < shortcut.length(); i++) {
            Object value = km.getBound(Character.toString(shortcut.charAt(i)));
            if (value instanceof KeyMap) {
                km = (KeyMap) value;
            } else {
                km.bind(shortcut.substring(i), action);
            }
        }
    }

    private static final String DOCUMENTATION_SHORTCUT = "\033\133\132"; //Shift-TAB
    private static final String CTRL_UP = "\033\133\061\073\065\101"; //Ctrl-UP
    private static final String CTRL_DOWN = "\033\133\061\073\065\102"; //Ctrl-DOWN
    private static final String[] SHORTCUT_FIXES = {
        "\033\015", //Alt-Enter (Linux)
        "\033\133\061\067\176", //F6/Alt-F1 (Mac)
        "\u001BO3P" //Alt-F1 (Linux)
    };

    private void documentation(JShellTool repl) {
        String buffer = in.getCursorBuffer().buffer.toString();
        int cursor = in.getCursorBuffer().cursor;
        String doc;
        if (prefix.isEmpty() && buffer.trim().startsWith("/")) {
            doc = repl.commandDocumentation(buffer, cursor);
        } else {
            doc = repl.analysis.documentation(prefix + buffer, cursor + prefix.length());
        }

        try {
            if (doc != null) {
                in.println();
                in.println(doc);
                in.redrawLine();
                in.flush();
            } else {
                in.beep();
            }
        } catch (IOException ex) {
            throw new IllegalStateException(ex);
        }
    }

    private static String commonPrefix(String str1, String str2) {
        for (int i = 0; i < str2.length(); i++) {
            if (!str1.startsWith(str2.substring(0, i + 1))) {
                return str2.substring(0, i);
            }
        }

        return str2;
    }

    @Override
    public boolean terminalEditorRunning() {
        Terminal terminal = in.getTerminal();
        if (terminal instanceof JShellUnixTerminal)
            return ((JShellUnixTerminal) terminal).isRaw();
        return false;
    }

    @Override
    public void suspend() {
        try {
            in.getTerminal().restore();
        } catch (Exception ex) {
            throw new IllegalStateException(ex);
        }
    }

    @Override
    public void resume() {
        try {
            in.getTerminal().init();
        } catch (Exception ex) {
            throw new IllegalStateException(ex);
        }
    }

    public void beforeUserCode() {
        input.setState(State.BUFFER);
    }

    public void afterUserCode() {
        input.setState(State.WAIT);
    }

    @Override
    public void replaceLastHistoryEntry(String source) {
        history.fullHistoryReplace(source);
    }

    //compute possible options/Fixes based on the selected FixComputer, present them to the user,
    //and perform the selected one:
    private void fixes(FixComputer computer) {
        String input = prefix + in.getCursorBuffer().toString();
        int cursor = prefix.length() + in.getCursorBuffer().cursor;
        FixResult candidates = computer.compute(repl, input, cursor);

        try {
            final boolean printError = candidates.error != null && !candidates.error.isEmpty();
            if (printError) {
                in.println(candidates.error);
            }
            if (candidates.fixes.isEmpty()) {
                in.beep();
                if (printError) {
                    in.redrawLine();
                    in.flush();
                }
            } else if (candidates.fixes.size() == 1 && !computer.showMenu) {
                if (printError) {
                    in.redrawLine();
                    in.flush();
                }
                candidates.fixes.get(0).perform(in);
            } else {
                List<Fix> fixes = new ArrayList<>(candidates.fixes);
                fixes.add(0, new Fix() {
                    @Override
                    public String displayName() {
                        return "Do nothing";
                    }

                    @Override
                    public void perform(ConsoleReader in) throws IOException {
                        in.redrawLine();
                    }
                });

                Map<Character, Fix> char2Fix = new HashMap<>();
                in.println();
                for (int i = 0; i < fixes.size(); i++) {
                    Fix fix = fixes.get(i);
                    char2Fix.put((char) ('0' + i), fix);
                    in.println("" + i + ": " + fixes.get(i).displayName());
                }
                in.print("Choice: ");
                in.flush();
                int read;

                read = in.readCharacter();

                Fix fix = char2Fix.get((char) read);

                if (fix == null) {
                    in.beep();
                    fix = fixes.get(0);
                }

                in.println();

                fix.perform(in);

                in.flush();
            }
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }

    /**
     * A possible action which the user can choose to perform.
     */
    public interface Fix {
        /**
         * A name that should be shown to the user.
         */
        public String displayName();
        /**
         * Perform the given action.
         */
        public void perform(ConsoleReader in) throws IOException;
    }

    /**
     * A factory for {@link Fix}es.
     */
    public abstract static class FixComputer {
        private final char shortcut;
        private final boolean showMenu;

        /**
         * Construct a new FixComputer. {@code shortcut} defines the key which should trigger this FixComputer.
         * If {@code showMenu} is {@code false}, and this computer returns exactly one {@code Fix},
         * no options will be show to the user, and the given {@code Fix} will be performed.
         */
        public FixComputer(char shortcut, boolean showMenu) {
            this.shortcut = shortcut;
            this.showMenu = showMenu;
        }

        /**
         * Compute possible actions for the given code.
         */
        public abstract FixResult compute(JShellTool repl, String code, int cursor);
    }

    /**
     * A list of {@code Fix}es with a possible error that should be shown to the user.
     */
    public static class FixResult {
        public final List<Fix> fixes;
        public final String error;

        public FixResult(List<Fix> fixes, String error) {
            this.fixes = fixes;
            this.error = error;
        }
    }

    private static final FixComputer[] FIX_COMPUTERS = new FixComputer[] {
        new FixComputer('v', false) { //compute "Introduce variable" Fix:
            @Override
            public FixResult compute(JShellTool repl, String code, int cursor) {
                String type = repl.analysis.analyzeType(code, cursor);
                if (type == null) {
                    return new FixResult(Collections.emptyList(), null);
                }
                return new FixResult(Collections.singletonList(new Fix() {
                    @Override
                    public String displayName() {
                        return "Create variable";
                    }
                    @Override
                    public void perform(ConsoleReader in) throws IOException {
                        in.redrawLine();
                        in.setCursorPosition(0);
                        in.putString(type + "  = ");
                        in.setCursorPosition(in.getCursorBuffer().cursor - 3);
                        in.flush();
                    }
                }), null);
            }
        },
        new FixComputer('i', true) { //compute "Add import" Fixes:
            @Override
            public FixResult compute(JShellTool repl, String code, int cursor) {
                QualifiedNames res = repl.analysis.listQualifiedNames(code, cursor);
                List<Fix> fixes = new ArrayList<>();
                for (String fqn : res.getNames()) {
                    fixes.add(new Fix() {
                        @Override
                        public String displayName() {
                            return "import: " + fqn;
                        }
                        @Override
                        public void perform(ConsoleReader in) throws IOException {
                            repl.state.eval("import " + fqn + ";");
                            in.println("Imported: " + fqn);
                            in.redrawLine();
                        }
                    });
                }
                if (res.isResolvable()) {
                    return new FixResult(Collections.emptyList(),
                                         "\nThe identifier is resolvable in this context.");
                } else {
                    String error = "";
                    if (fixes.isEmpty()) {
                        error = "\nNo candidate fully qualified names found to import.";
                    }
                    if (!res.isUpToDate()) {
                        error += "\nResults may be incomplete; try again later for complete results.";
                    }
                    return new FixResult(fixes, error);
                }
            }
        }
    };

    private static final class JShellUnixTerminal extends NoInterruptUnixTerminal {

        private final StopDetectingInputStream input;

        public JShellUnixTerminal(StopDetectingInputStream input) throws Exception {
            this.input = input;
        }

        public boolean isRaw() {
            try {
                return getSettings().get("-a").contains("-icanon");
            } catch (IOException | InterruptedException ex) {
                return false;
            }
        }

        @Override
        public InputStream wrapInIfNeeded(InputStream in) throws IOException {
            return input.setInputStream(super.wrapInIfNeeded(in));
        }

        @Override
        public void disableInterruptCharacter() {
        }

        @Override
        public void enableInterruptCharacter() {
        }

    }

    private static final class JShellWindowsTerminal extends WindowsTerminal {

        private final StopDetectingInputStream input;

        public JShellWindowsTerminal(StopDetectingInputStream input) throws Exception {
            this.input = input;
        }

        @Override
        public void init() throws Exception {
            super.init();
            setAnsiSupported(false);
        }

        @Override
        public InputStream wrapInIfNeeded(InputStream in) throws IOException {
            return input.setInputStream(super.wrapInIfNeeded(in));
        }

    }
}