package org.simantics.modeling;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

import org.simantics.databoard.Bindings;
import org.simantics.db.ReadGraph;
import org.simantics.db.Resource;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.request.Read;
import org.simantics.scl.compiler.environment.LocalEnvironment;
import org.simantics.scl.compiler.environment.specification.EnvironmentSpecification;
import org.simantics.scl.compiler.errors.CompilationError;
import org.simantics.scl.compiler.errors.ErrorSeverity;
import org.simantics.scl.compiler.module.repository.ImportFailure;
import org.simantics.scl.compiler.module.repository.ImportFailureException;
import org.simantics.scl.compiler.runtime.RuntimeEnvironment;
import org.simantics.scl.compiler.top.ExpressionEvaluator;
import org.simantics.scl.compiler.top.SCLExpressionCompilationException;
import org.simantics.structural.stubs.StructuralResource2;

public class ComponentTypeScriptRequest implements Read<ComponentTypeScriptResult> {

    private Resource script;
    private Resource componentType;

    public ComponentTypeScriptRequest(Resource script, Resource componentType) {
        this.script = script;
        this.componentType = componentType;
    }
    
    @Override
    public ComponentTypeScriptResult perform(ReadGraph graph) throws DatabaseException {
        IComponentTypeScriptEnvironmentFactory factory = graph.adapt(componentType, IComponentTypeScriptEnvironmentFactory.class);

        EnvironmentSpecification spec = factory.getRuntimeEnvironmentSpecification(graph, componentType);
        
        RuntimeEnvironment runtime;
        try {
            runtime = graph.syncRequest(new ComponentTypeScriptRuntimeEnvironmentRequest(spec));
        }
        catch (DatabaseException e) {
            if (e.getCause() instanceof ImportFailureException) {
                ImportFailureException cause = (ImportFailureException)e.getCause();
                // if one of the scl modules can not be imported just show an error
                // at the very start of the editor
                List<CompilationError> errors = new ArrayList<CompilationError>();
                for (ImportFailure failure : cause.failures) {
                    errors.add(new CompilationError(0, failure.toString(),
                            failure.reason == ImportFailure.MODULE_DOES_NOT_EXIST_REASON ? ErrorSeverity.ERROR : ErrorSeverity.IMPORT_ERROR));
                }
                return new ComponentTypeScriptResult(errors, null);
            }
            else {
                throw e;
            }
        }
        
        StructuralResource2 str = StructuralResource2.getInstance(graph);
        String code = graph.getRelatedValue(script, str.ComponentTypeScript_code, Bindings.STRING);
        
        ExpressionEvaluator eval = new ExpressionEvaluator(runtime, code);
        eval.interpretIfPossible(false).parseAsBlock(true);
        
        // set the local environment if necessary
        LocalEnvironment local = factory.getLocalEnvironment(graph, componentType);
        if (local != null)
            eval.localEnvironment(local);
        
        Object result;
        try {
            result = eval.eval();
        }
        catch (SCLExpressionCompilationException e) {
            return new ComponentTypeScriptResult(Arrays.asList(e.getErrors()), null);
        }
        
        return new ComponentTypeScriptResult(Collections.<CompilationError>emptyList(), 
                                             result, 
                                             factory.getModuleReads(local), 
                                             factory.getModuleWrites(local));
    }
    
    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result
                + ((componentType == null) ? 0 : componentType.hashCode());
        result = prime * result + ((script == null) ? 0 : script.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        ComponentTypeScriptRequest other = (ComponentTypeScriptRequest) obj;
        if (componentType == null) {
            if (other.componentType != null)
                return false;
        } else if (!componentType.equals(other.componentType))
            return false;
        if (script == null) {
            if (other.script != null)
                return false;
        } else if (!script.equals(other.script))
            return false;
        return true;
    }

}