/*
 * 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.server;

import android.util.Slog;
import com.google.android.collect.Lists;

import java.util.ArrayList;

/**
 * Parsed event from native side of {@link NativeDaemonConnector}.
 */
public class NativeDaemonEvent {

    // TODO: keep class ranges in sync with ResponseCode.h
    // TODO: swap client and server error ranges to roughly mirror HTTP spec

    private final int mCmdNumber;
    private final int mCode;
    private final String mMessage;
    private final String mRawEvent;
    private String[] mParsed;

    private NativeDaemonEvent(int cmdNumber, int code, String message, String rawEvent) {
        mCmdNumber = cmdNumber;
        mCode = code;
        mMessage = message;
        mRawEvent = rawEvent;
        mParsed = null;
    }

    public int getCmdNumber() {
        return mCmdNumber;
    }

    public int getCode() {
        return mCode;
    }

    public String getMessage() {
        return mMessage;
    }

    @Deprecated
    public String getRawEvent() {
        return mRawEvent;
    }

    @Override
    public String toString() {
        return mRawEvent;
    }

    /**
     * Test if event represents a partial response which is continued in
     * additional subsequent events.
     */
    public boolean isClassContinue() {
        return mCode >= 100 && mCode < 200;
    }

    /**
     * Test if event represents a command success.
     */
    public boolean isClassOk() {
        return mCode >= 200 && mCode < 300;
    }

    /**
     * Test if event represents a remote native daemon error.
     */
    public boolean isClassServerError() {
        return mCode >= 400 && mCode < 500;
    }

    /**
     * Test if event represents a command syntax or argument error.
     */
    public boolean isClassClientError() {
        return mCode >= 500 && mCode < 600;
    }

    /**
     * Test if event represents an unsolicited event from native daemon.
     */
    public boolean isClassUnsolicited() {
        return isClassUnsolicited(mCode);
    }

    private static boolean isClassUnsolicited(int code) {
        return code >= 600 && code < 700;
    }

    /**
     * Verify this event matches the given code.
     *
     * @throws IllegalStateException if {@link #getCode()} doesn't match.
     */
    public void checkCode(int code) {
        if (mCode != code) {
            throw new IllegalStateException("Expected " + code + " but was: " + this);
        }
    }

    /**
     * Parse the given raw event into {@link NativeDaemonEvent} instance.
     *
     * @throws IllegalArgumentException when line doesn't match format expected
     *             from native side.
     */
    public static NativeDaemonEvent parseRawEvent(String rawEvent) {
        final String[] parsed = rawEvent.split(" ");
        if (parsed.length < 2) {
            throw new IllegalArgumentException("Insufficient arguments");
        }

        int skiplength = 0;

        final int code;
        try {
            code = Integer.parseInt(parsed[0]);
            skiplength = parsed[0].length() + 1;
        } catch (NumberFormatException e) {
            throw new IllegalArgumentException("problem parsing code", e);
        }

        int cmdNumber = -1;
        if (isClassUnsolicited(code) == false) {
            if (parsed.length < 3) {
                throw new IllegalArgumentException("Insufficient arguemnts");
            }
            try {
                cmdNumber = Integer.parseInt(parsed[1]);
                skiplength += parsed[1].length() + 1;
            } catch (NumberFormatException e) {
                throw new IllegalArgumentException("problem parsing cmdNumber", e);
            }
        }

        final String message = rawEvent.substring(skiplength);

        return new NativeDaemonEvent(cmdNumber, code, message, rawEvent);
    }

    /**
     * Filter the given {@link NativeDaemonEvent} list, returning
     * {@link #getMessage()} for any events matching the requested code.
     */
    public static String[] filterMessageList(NativeDaemonEvent[] events, int matchCode) {
        final ArrayList<String> result = Lists.newArrayList();
        for (NativeDaemonEvent event : events) {
            if (event.getCode() == matchCode) {
                result.add(event.getMessage());
            }
        }
        return result.toArray(new String[result.size()]);
    }

    /**
     * Find the Nth field of the event.
     *
     * This ignores and code or cmdNum, the first return value is given for N=0.
     * Also understands "\"quoted\" multiword responses" and tries them as a single field
     */
    public String getField(int n) {
        if (mParsed == null) {
            mParsed = unescapeArgs(mRawEvent);
        }
        n += 2; // skip code and command#
        if (n > mParsed.length) return null;
            return mParsed[n];
        }

    public static String[] unescapeArgs(String rawEvent) {
        final boolean DEBUG_ROUTINE = false;
        final String LOGTAG = "unescapeArgs";
        final ArrayList<String> parsed = new ArrayList<String>();
        final int length = rawEvent.length();
        int current = 0;
        int wordEnd = -1;
        boolean quoted = false;

        if (DEBUG_ROUTINE) Slog.e(LOGTAG, "parsing '" + rawEvent + "'");
        if (rawEvent.charAt(current) == '\"') {
            quoted = true;
            current++;
        }
        while (current < length) {
            // find the end of the word
            char terminator = quoted ? '\"' : ' ';
            wordEnd = current;
            while (wordEnd < length && rawEvent.charAt(wordEnd) != terminator) {
                if (rawEvent.charAt(wordEnd) == '\\') {
                    // skip the escaped char
                    ++wordEnd;
                }
                ++wordEnd;
            }
            if (wordEnd > length) wordEnd = length;
            String word = rawEvent.substring(current, wordEnd);
            current += word.length();
            if (!quoted) {
                word = word.trim();
            } else {
                current++;  // skip the trailing quote
            }
            // unescape stuff within the word
            word = word.replace("\\\\", "\\");
            word = word.replace("\\\"", "\"");

            if (DEBUG_ROUTINE) Slog.e(LOGTAG, "found '" + word + "'");
            parsed.add(word);

            // find the beginning of the next word - either of these options
            int nextSpace = rawEvent.indexOf(' ', current);
            int nextQuote = rawEvent.indexOf(" \"", current);
            if (DEBUG_ROUTINE) {
                Slog.e(LOGTAG, "nextSpace=" + nextSpace + ", nextQuote=" + nextQuote);
            }
            if (nextQuote > -1 && nextQuote <= nextSpace) {
                quoted = true;
                current = nextQuote + 2;
            } else {
                quoted = false;
                if (nextSpace > -1) {
                    current = nextSpace + 1;
                }
            } // else we just start the next word after the current and read til the end
            if (DEBUG_ROUTINE) {
                Slog.e(LOGTAG, "next loop - current=" + current +
                        ", length=" + length + ", quoted=" + quoted);
            }
        }
        return parsed.toArray(new String[parsed.size()]);
    }
}