/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.ide.eclipse.gltrace.format;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Model a single GL API function call's specification.
 */
public class GLAPISpec {
    private static final String GL_SPECS_FILE = "/entries.in"; //$NON-NLS-1$
    private static final String GLES2_ENTRIES_HEADER_V1 =
            "# com.android.ide.eclipse.gltrace.glentries, v1"; //$NON-NLS-1$
    private static Map<String, GLAPISpec> sApiSpecs;

    private final String mGLFunction;
    private final GLDataTypeSpec mReturnType;
    private final List<GLDataTypeSpec> mArgs;

    private GLAPISpec(String glFunction, GLDataTypeSpec returnType, List<GLDataTypeSpec> args) {
        mGLFunction = glFunction;
        mReturnType = returnType;
        mArgs = args;
    }

    public String getFunction() {
        return mGLFunction;
    }

    public GLDataTypeSpec getReturnValue() {
        return mReturnType;
    }

    public List<GLDataTypeSpec> getArgs() {
        return mArgs;
    }

    public static Map<String, GLAPISpec> getSpecs() {
        if (sApiSpecs == null) {
            sApiSpecs = parseApiSpecs(GLAPISpec.class.getResourceAsStream(GL_SPECS_FILE));
        }

        return sApiSpecs;
    }

    private static Map<String, GLAPISpec> parseApiSpecs(InputStream specFile) {
        BufferedReader reader = new BufferedReader(new InputStreamReader(specFile));
        Map<String, GLAPISpec> specs = new HashMap<String, GLAPISpec>(400);

        try{
            String header = reader.readLine().trim();
            assert header.equals(GLES2_ENTRIES_HEADER_V1);

            String line;
            while ((line = reader.readLine()) != null) {
                // strip away the comments
                int commentPos = line.indexOf('#');
                if (commentPos != -1) {
                    line = line.substring(0, commentPos);
                }
                line = line.trim();

                // parse non empty lines
                if (line.length() > 0) {
                    GLAPISpec spec = parseLine(line);
                    specs.put(spec.getFunction(), spec);
                }
            }

            specFile.close();
        } catch (IOException e) {
            // this is unlikely to happen as the file is present within this .jar file.
            // Even if it does happen, we just return whatever we've read till now. The net
            // impact will be that the function calls will not be parsed fully and will just
            // display the function name.
        }

        return specs;
    }

    /**
     * Parse a GL API Specification entry from "/entries.in". Each line is of the format:
     * {@code returnType, funcName, arg*}. This method is package private for testing.
     */
    static GLAPISpec parseLine(String line) {
        List<String> words = Arrays.asList(line.split(","));

        String retType = words.get(0).trim();
        String func = words.get(1).trim();
        List<String> argDefinitions = words.subList(2, words.size());

        List<GLDataTypeSpec> glArgs = new ArrayList<GLDataTypeSpec>(argDefinitions.size()/2);
        for (String argDefn: argDefinitions) {
            // an argDefn is something like: "const GLvoid* data"
            argDefn = argDefn.trim();
            int lastSeparator = argDefn.lastIndexOf(' ');
            if (lastSeparator == -1) {
                // no space => a void type with no argument name
                glArgs.add(new GLDataTypeSpec(argDefn, null));
            } else {
                // everything upto the last space is the type
                String type = argDefn.substring(0, lastSeparator);

                // and the last word is the variable name
                String name = argDefn.substring(lastSeparator + 1);
                glArgs.add(new GLDataTypeSpec(type, name));
            }
        }

        return new GLAPISpec(func, new GLDataTypeSpec(retType, null), glArgs);
    }
}