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package org.graalvm.polyglot;

import java.util.Arrays;
import java.util.Objects;

import org.graalvm.collections.EconomicMap;
import org.graalvm.collections.EconomicSet;
import org.graalvm.collections.Equivalence;
import org.graalvm.collections.MapCursor;
import org.graalvm.collections.UnmodifiableEconomicSet;

Represents an access policy for polyglot builtins in the guest languages.
 If the two predefined access policies NONE and ALL are not sufficient then a custom access configuration may be created using newBuilder(). This allows to grant individual access rights between the language. 

The following access rights may be granted:

The ability to evaluate code between two or just for one language. If a language has access to at least one other language then the polyglot eval builtin will be available, otherwise access to that builtin might be restricted. The concrete name of the polyglot eval builtin is language specific. In JavaScript it is called Polyglot.eval.
The ability to access members in the polyglot
bindings. The names of the guest language builtins to access polyglot bindings are language specific. In JavaScript they are called Polyglot.import and
Polyglot.export.
 Access to polyglot evaluation and bindings builtins are always enabled when access policy ALL is used. In this mode polyglot evaluation builtins are available even if there is just one installed language available. 
Since:
19.0/**
 * Represents an access policy for polyglot builtins in the guest languages.
 * <p>
 * If the two predefined access policies {@link #NONE} and {@link #ALL} are not sufficient then a
 * custom access configuration may be created using {@link #newBuilder()}. This allows to grant
 * individual access rights between the language.
 * <p>
 * The following access rights may be granted:
 * <ul>
 * <li>The ability to evaluate code {@link Builder#allowEvalBetween(String...) between} two or just
 * for {@link Builder#allowEval(String, String) one} language. If a language has access to at least
 * one other language then the polyglot eval builtin will be available, otherwise access to that
 * builtin might be restricted. The concrete name of the polyglot eval builtin is language specific.
 * In JavaScript it is called <code>Polyglot.eval</code>.
 * <li>The ability to access members in the {@link Builder#allowBindingsAccess(String) polyglot
 * bindings}. The names of the guest language builtins to access polyglot bindings are language
 * specific. In JavaScript they are called <code>Polyglot.import</code> and
 * <code>Polyglot.export</code>.
 * </ul>
 * Access to polyglot evaluation and bindings builtins are always enabled when access policy
 * {@link #ALL} is used. In this mode polyglot evaluation builtins are available even if there is
 * just one {@link Engine#getLanguages() installed} language available.
 *
 * @since 19.0
 */
public final class PolyglotAccess {

    private static final UnmodifiableEconomicSet<String> EMPTY = EconomicSet.create();

    private final EconomicMap<String, EconomicSet<String>> evalAccess;
    private final EconomicSet<String> bindingsAccess;
    private final boolean allAccess;

    PolyglotAccess(boolean allAccess, EconomicMap<String, EconomicSet<String>> access, EconomicSet<String> bindingsAccess) {
        this.allAccess = allAccess;
        this.evalAccess = copyMap(access);
        this.bindingsAccess = bindingsAccess;
    }

    private static EconomicMap<String, EconomicSet<String>> copyMap(EconomicMap<String, EconomicSet<String>> values) {
        if (values == null) {
            return null;
        }
        EconomicMap<String, EconomicSet<String>> newMap = EconomicMap.create(Equivalence.DEFAULT, values);
        MapCursor<String, EconomicSet<String>> cursor = newMap.getEntries();
        while (cursor.advance()) {
            newMap.put(cursor.getKey(), EconomicSet.create(Equivalence.DEFAULT, cursor.getValue()));
        }
        return newMap;
    }

    String validate(UnmodifiableEconomicSet<String> availableLanguages) {
        if (evalAccess != null) {
            MapCursor<String, EconomicSet<String>> entries = evalAccess.getEntries();
            while (entries.advance()) {
                String invalidKey = null;
                if (!availableLanguages.contains(entries.getKey())) {
                    invalidKey = entries.getKey();
                }
                if (invalidKey == null) {
                    for (String entry : entries.getValue()) {
                        if (!availableLanguages.contains(entry)) {
                            invalidKey = entry;
                            break;
                        }
                    }
                }
                if (invalidKey != null) {
                    return String.format("Language '%s' configured in polyglot evaluation rule %s -> %s is not installed or available.",
                                    invalidKey, entries.getKey(), toStringSet(entries.getValue()));
                }
            }
        }

        if (bindingsAccess != null) {
            for (String language : bindingsAccess) {
                if (!availableLanguages.contains(language)) {
                    return String.format("Language '%s' configured in polyglot bindings access rule is not installed or available.",
                                    language);
                }
            }
        }
        return null;

    }

    static String toStringSet(EconomicSet<String> set) {
        StringBuilder b = new StringBuilder();
        String sep = "";
        for (String entry : set) {
            b.append(sep);
            b.append(entry);
            sep = ", ";
        }
        return b.toString();
    }

    UnmodifiableEconomicSet<String> getEvalAccess(String language) {
        if (allAccess) {
            return null;
        } else {
            if (evalAccess == null) {
                return EMPTY;
            } else {
                EconomicSet<String> a = evalAccess.get(language);
                if (a == null) {
                    return EMPTY;
                }
                return a;
            }
        }
    }

    UnmodifiableEconomicSet<String> getBindingsAccess() {
        if (allAccess) {
            return null;
        } else {
            if (bindingsAccess == null) {
                return EMPTY;
            } else {
                return bindingsAccess;
            }
        }
    }

    
Provides guest languages no access to other languages using polyglot builtins evaluation and
binding builtins.
Since:
19.0/**
     * Provides guest languages no access to other languages using polyglot builtins evaluation and
     * binding builtins.
     *
     * @since 19.0
     */
    public static final PolyglotAccess NONE = new PolyglotAccess(false, null, null);

    
Provides guest languages full access to other languages using polyglot evaluation and binding
builtins.
Since:
19.0/**
     * Provides guest languages full access to other languages using polyglot evaluation and binding
     * builtins.
     *
     * @since 19.0
     */
    public static final PolyglotAccess ALL = new PolyglotAccess(true, null, null);

    
Creates a new custom polyglot access configuration builder. A polyglot access builder starts
with no access rights.
Since:
19.2/**
     * Creates a new custom polyglot access configuration builder. A polyglot access builder starts
     * with no access rights.
     *
     * @since 19.2
     */
    public static Builder newBuilder() {
        return NONE.new Builder();
    }

    
A builder for a polyglot access configuration. Builder instances are not thread-safe.
Since:
19.2/**
     * A builder for a polyglot access configuration. Builder instances are not thread-safe.
     *
     * @since 19.2
     */
    public final class Builder {

        private EconomicMap<String, EconomicSet<String>> evalAccess;
        private EconomicSet<String> bindingsAccess;

        Builder() {
        }

        
Allows bidirectional evaluation of code between the given languages. When called with
language "A" and language "B", this is equivalent to calling
allowEval("A", "B") and
allowEval("B", "A"). If called with more than two then all language evaluation combinations will be allowed. This method potentially overrides already configured access rights with allowEval(String, String) or denyEval(String, String). The given language array must be null and individual languages must not be
null.
See Also:
allowEval(String, String)
Since:
19.2/**
         * Allows bidirectional evaluation of code between the given languages. When called with
         * language <code>"A"</code> and language <code>"B"</code>, this is equivalent to calling
         * <code>{@linkplain #allowEval(String, String) allowEval}("A", "B")</code> and
         * <code>{@linkplain #allowEval(String, String) allowEval}("B", "A")</code>. If called with
         * more than two then all language evaluation combinations will be allowed. This method
         * potentially overrides already configured access rights with
         * {@link #allowEval(String, String)} or {@link #denyEval(String, String)}. The given
         * language array must be <code>null</code> and individual languages must not be
         * <code>null</code>.
         *
         * @see #allowEval(String, String)
         * @since 19.2
         */
        public Builder allowEvalBetween(String... languages) {
            Objects.requireNonNull(languages);
            if (evalAccess == null) {
                evalAccess = EconomicMap.create();
            }
            for (String language : languages) {
                Objects.requireNonNull(language);
                EconomicSet<String> languageAccess = evalAccess.get(language);
                if (languageAccess == null) {
                    languageAccess = EconomicSet.create();
                    evalAccess.put(language, languageAccess);
                }
                languageAccess.addAll(Arrays.asList(languages));
            }
            return this;
        }

        
Denies bidirectional evaluation of code between the given languages. When called with
language "A" and language "B", this is equivalent to calling
denyEval("A", "B") and
denyEval("B", "A"). If called with more than two then all language access combinations will be denied. This method potentially overrides already configured access rights with allowEval(String, String) or denyEval(String, String). The given language array must be null and individual languages must not be
null.
See Also:
denyEval(String, String)
Since:
19.2/**
         * Denies bidirectional evaluation of code between the given languages. When called with
         * language <code>"A"</code> and language <code>"B"</code>, this is equivalent to calling
         * <code>{@linkplain #denyEval(String, String) denyEval}("A", "B")</code> and
         * <code>{@linkplain #denyEval(String, String) denyEval}("B", "A")</code>. If called with
         * more than two then all language access combinations will be denied. This method
         * potentially overrides already configured access rights with
         * {@link #allowEval(String, String)} or {@link #denyEval(String, String)}. The given
         * language array must be <code>null</code> and individual languages must not be
         * <code>null</code>.
         *
         * @see #denyEval(String, String)
         * @since 19.2
         */
        public Builder denyEvalBetween(String... languages) {
            Objects.requireNonNull(languages);
            if (evalAccess != null) {
                for (String language : languages) {
                    Objects.requireNonNull(language);
                    EconomicSet<String> languageAccess = evalAccess.get(language);
                    if (languageAccess != null) {
                        languageAccess.removeAll(Arrays.asList(languages));
                    }
                }
            }
            return this;
        }

        
Allows evaluation of code by one language of another. This method only allows one-way
evaluation access. Every language always has implicitly access to itself. If a language
has access to one ore more different languages then the guest application will have
access to polyglot evaluation builtins. If a language has no access granted to another
language then access to polyglot evaluation builtins is denied.
See Also:
allowEvalBetween(String...)
Since:
19.2/**
         * Allows evaluation of code by one language of another. This method only allows one-way
         * evaluation access. Every language always has implicitly access to itself. If a language
         * has access to one ore more different languages then the guest application will have
         * access to polyglot evaluation builtins. If a language has no access granted to another
         * language then access to polyglot evaluation builtins is denied.
         *
         * @see #allowEvalBetween(String...)
         * @since 19.2
         */
        public Builder allowEval(String from, String to) {
            Objects.requireNonNull(from);
            Objects.requireNonNull(to);
            if (evalAccess == null) {
                evalAccess = EconomicMap.create();
            }
            EconomicSet<String> languageAccess = evalAccess.get(from);
            if (languageAccess == null) {
                languageAccess = EconomicSet.create();
                evalAccess.put(from, languageAccess);
            }
            languageAccess.add(to);
            return this;
        }

        
Denies evaluation of code by one language of another. This method only denies one-way
evaluation. Every language has always evaluation access to itself. This access cannot be
denied.
See Also:
denyEvalBetween(String...)
Since:
19.2/**
         * Denies evaluation of code by one language of another. This method only denies one-way
         * evaluation. Every language has always evaluation access to itself. This access cannot be
         * denied.
         *
         * @see #denyEvalBetween(String...)
         * @since 19.2
         */
        public Builder denyEval(String from, String to) {
            Objects.requireNonNull(from);
            Objects.requireNonNull(to);
            if (evalAccess != null) {
                EconomicSet<String> languageAccess = evalAccess.get(from);
                if (languageAccess != null) {
                    languageAccess.remove(to);
                }
            }
            return this;
        }

        
Allows access to polyglot bindings for a language. The names of the guest language
builtins to access polyglot bindings are language specific. In JavaScript they are called
Polyglot.import and Polyglot.export.
See Also:
denyBindingsAccess(String)
Since:
19.2/**
         * Allows access to polyglot bindings for a language. The names of the guest language
         * builtins to access polyglot bindings are language specific. In JavaScript they are called
         * <code>Polyglot.import</code> and <code>Polyglot.export</code>.
         *
         * @see #denyBindingsAccess(String)
         * @since 19.2
         */
        public Builder allowBindingsAccess(String language) {
            Objects.requireNonNull(language);
            if (bindingsAccess == null) {
                bindingsAccess = EconomicSet.create();
            }
            bindingsAccess.add(language);
            return this;
        }

        
Denies access to polyglot bindings for a language. The provided language must not be
null.
See Also:
allowBindingsAccess(String)
Since:
19.2/**
         * Denies access to polyglot bindings for a language. The provided language must not be
         * <code>null</code>.
         *
         * @see #allowBindingsAccess(String)
         * @since 19.2
         */
        public Builder denyBindingsAccess(String language) {
            Objects.requireNonNull(language);
            if (bindingsAccess != null) {
                bindingsAccess.remove(language);
            }
            return this;
        }

        
Creates an instance of the custom polyglot access configuration. This method may be
called multiple times to create more than one independent instances.
Since:
19.2/**
         * Creates an instance of the custom polyglot access configuration. This method may be
         * called multiple times to create more than one independent instances.
         *
         * @since 19.2
         */
        public PolyglotAccess build() {
            return new PolyglotAccess(false, evalAccess, bindingsAccess);
        }
    }
}