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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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*/

package com.google.refine.expr.functions.strings;

import java.io.UnsupportedEncodingException;
import java.util.Properties;

import com.google.refine.ProjectManager;
import com.google.refine.ProjectMetadata;
import com.google.refine.expr.EvalError;
import com.google.refine.grel.ControlFunctionRegistry;
import com.google.refine.grel.Function;
import com.google.refine.model.Project;

public class Reinterpret implements Function {

    @Override
    public Object call(Properties bindings, Object[] args) {
        if (args.length == 2 || args.length == 3) {
            Object o1 = args[0];
            Object o2 = args[1];
            if (o1 != null && o2 != null && o2 instanceof String) {
                String str = (o1 instanceof String) ? (String) o1 : o1.toString();
                String decoder;
                String encoder;

                encoder = (String) o2;
                if (args.length == 2) {
                    Project project = (Project) bindings.get("project");
                    ProjectMetadata metadata = ProjectManager.singleton.getProjectMetadata(project.id);
                    decoder = metadata.getEncoding(); // can return "" for broken projects
                } else {
                    decoder = (String) args[2];
                }
                return reinterpret(str, decoder, encoder);
            }
        }
        return new EvalError(ControlFunctionRegistry.getFunctionName(this) + " expects 2 or 3 arguments");
    }

    private Object reinterpret(String str, String decoder, String encoder) {
        String result = null;

        byte[] bytes;
        if (decoder == null || decoder.isEmpty()) {
            bytes = str.getBytes();
        } else {
            try {
                bytes = str.getBytes(decoder);
            } catch (UnsupportedEncodingException e) {
                return new EvalError(ControlFunctionRegistry.getFunctionName(this) + ": source encoding '" + decoder + "' is not available or recognized.");
            }
        }
        try {
            if (encoder == null || encoder.isEmpty()) {
                result = new String(bytes); // system default encoding
            } else {
                result = new String(bytes, encoder);
            }
        } catch (UnsupportedEncodingException e) {
            return new EvalError(ControlFunctionRegistry.getFunctionName(this) + ": encoding '" + encoder + "' is not available or recognized.");
        }
                        
        return result;
    }
    
    @Override
    public String getDescription() {
        return "Returns s reinterpreted thru the given encoder.";
    }
    
    @Override
    public String getParams() {
        return "string s, string encoder";
    }
    
    @Override
    public String getReturns() {
        return "string";
    }
}
