package org.simantics.scl.compiler.source;

import java.io.IOException;
import java.io.Reader;
import java.util.Arrays;

import org.simantics.scl.compiler.compilation.SCLCompiler;
import org.simantics.scl.compiler.environment.EnvironmentFactoryImpl;
import org.simantics.scl.compiler.errors.CompilationErrorFormatter;
import org.simantics.scl.compiler.errors.Failable;
import org.simantics.scl.compiler.errors.Failure;
import org.simantics.scl.compiler.errors.Success;
import org.simantics.scl.compiler.internal.codegen.types.JavaReferenceValidator;
import org.simantics.scl.compiler.internal.codegen.types.JavaReferenceValidatorFactory;
import org.simantics.scl.compiler.internal.codegen.types.RuntimeJavaReferenceValidator;
import org.simantics.scl.compiler.module.ImportDeclaration;
import org.simantics.scl.compiler.module.Module;
import org.simantics.scl.compiler.module.options.ModuleCompilationOptions;
import org.simantics.scl.compiler.module.repository.ModuleRepository;
import org.simantics.scl.compiler.module.repository.UpdateListener;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public abstract class TextualModuleSource implements ModuleSource {
    private static final Logger LOGGER = LoggerFactory.getLogger(TextualModuleSource.class);
    
    public static final ImportDeclaration[] DEFAULT_IMPORTS = new ImportDeclaration[] {
        new ImportDeclaration("Builtin", ""),
        new ImportDeclaration("Prelude", "")
    };
    
    private final String moduleName;
    private final double priority;
    
    public TextualModuleSource(String moduleName, double priority) {
        this.moduleName = moduleName;
        this.priority = priority;
    }
    
    public TextualModuleSource(String moduleName) {
        this(moduleName, 0.0);
    }
    
    @Override
    public ClassLoader getClassLoader() {
        return getClass().getClassLoader();
    }

    protected abstract Reader getSourceReader(UpdateListener listener) throws IOException;
    protected JavaReferenceValidator<?, ?, ?, ?> getJavaReferenceValidator() {
        return new RuntimeJavaReferenceValidator(getClassLoader());
    }
    
    public String getSourceText(UpdateListener listener) throws IOException {
        Reader reader = getSourceReader(listener);
        char[] buffer = new char[65536];
        int pos = 0;
        try {
            while(true) {
                int count = reader.read(buffer, pos, buffer.length-pos);
                if(count == -1)
                    return new String(buffer, 0, pos);
                pos += count;
                if(pos == buffer.length)
                    buffer = Arrays.copyOf(buffer, 2*buffer.length);
            }
        } finally {
            reader.close();
        }
    }
    
    protected ImportDeclaration[] getBuiltinImports(UpdateListener listener) {
        return DEFAULT_IMPORTS;
    }
    
    @Override
    public String getModuleName() {
        return moduleName;
    }
    
    @SuppressWarnings("unchecked")
    @Override
    public Failable<Module> compileModule(final ModuleRepository environment, final UpdateListener listener, ModuleCompilationOptions options) {
        SCLCompiler compiler = new SCLCompiler(options, getJavaReferenceValidatorFactory());
        try {
            compiler.addSource(getSourceReader(listener));
            compiler.compile(
                    new EnvironmentFactoryImpl(
                            environment, 
                            getBuiltinImports(listener),
                            listener),
                    moduleName);
            if(compiler.getErrorLog().hasNoErrors())
                return new Success<Module>(compiler.getModule());
            else {
                LOGGER.error("While compiling " + getModuleName() + ":");
                LOGGER.error(CompilationErrorFormatter.toString(getSourceReader(null), compiler.getErrorLog().getErrors()));
                return new Failure(compiler.getErrorLog().getErrors());
            }
        } catch (IOException e) {
            return new Failure(e);
        }
    }
    
    public JavaReferenceValidatorFactory getJavaReferenceValidatorFactory() {
        return new JavaReferenceValidatorFactory() {
            
            @Override
            public JavaReferenceValidator<Object, Object, Object, Object> getJavaReferenceValidator(String context) {
                return (JavaReferenceValidator<Object, Object, Object, Object>)TextualModuleSource.this.getJavaReferenceValidator();
            }
            
            @Override
            public JavaReferenceValidator<Object, Object, Object, Object> getDefaultJavaReferenceValidator() {
                return (JavaReferenceValidator<Object, Object, Object, Object>)TextualModuleSource.this.getJavaReferenceValidator();
            }
        };
    }

    @Override
    public double getPriority() {
        return priority;
    }
    
    @Override
    public String toString() {
        return getClass().getSimpleName() + "(" + moduleName + ")";
    }
    
    public boolean isUpdateable() {
        return false;
    }
    
    public void update(String newSourceText) {
        throw new UnsupportedOperationException();
    }
}