/*
Copyright 2021 Intel Corporation

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.
*/


// 
// This is a helper module for parsing and enumerating Mesh Agent log entries
//

//
// This function parses a log entry, and and pushes each parsed log entry into the results array
//
function parseLine(entry)
{

    // Use a regex to parse the log entry
    var test = entry.match(/^\[.*M\]/);
    if (test == null)
    {
        // Use a regex to find a windows crash entry
        test = entry.match(/\[.+ => .+:[0-9]+\]/);
        if (test != null)
        {
            // Windows Crash Entry
            var file = test[0].substring(1).match(/(?!.+ ).+(?=:)/);
            var line = test[0].match(/(?!:)[0-9]+(?=\]$)/);
            var fn = test[0].match(/(?!\[).+(?= =>)/);

            if (file != null) { this.results.peek().f = file[0].trim(); }
            if (line != null) { this.results.peek().l = line[0]; }
            if (fn != null) { this.results.peek().fn = fn[0]; }
        }
        else
        {
            // On linux, use a regex to determine if a crash entry contains symbol info
            test = entry.match(/^[\.\/].+\(\) \[0x[0-9a-fA-F]+\]$/);
            if (test != null)
            {
                // Linux Crash Stack with no symbols
                test = test[0].match(/(?!\[)0x[0-9a-fA-F]+(?=\]$)/);
                if (test != null)
                {
                    if (this.results.peek().sx == null) { this.results.peek().sx = []; }
                    this.results.peek().sx.unshift(test[0]);
                }
            }
            else
            {
                // use a regex to try to finx the CrashID on linux
                test = entry.match(/^\[.+_[0-9a-fA-F]{16}\]$/);
                if(test!=null)
                {
                    // Linux Crash ID
                    test = test[0].match(/(?!_)[0-9a-fA-F]{16}(?=\]$)/);
                    this.results.peek().h = test[0];
                }
            }

            // Use a regex to find the crash entry
            test = entry.match(/(?!^=>)\/+.+:[0-9]+$/);
            if(test!=null)
            {
                // Linux Crash Entry
                if (this.results.peek().s == null) { this.results.peek().s = []; }
                this.results.peek().s.unshift(test[0]);
            }
            
        }
        return;
    }
    test = test[0];

    // Parse out the timestamp
    var dd = test.substring(1, test.length -1);
    var c = dd.split(' ');
    var t = c[1].split(':');
    if (c[2] == 'PM') { t[0] = parseInt(t[0]) + 12; if (t[0] == 24) { t[0] = 0; } }

    // Parse out the message and the agent hash
    var d = Date.parse(c[0] + 'T' + t.join(':'));
    var msg = entry.substring(test.length).trim();
    var hash = msg.match(/^\[[0-9a-fA-F]{16}\]/);
    if (hash != null)
    {
        hash = hash[0].substring(1, hash[0].length - 1);
        msg = msg.substring(hash.length + 2).trim();
    }
    else
    {
        hash = msg.match(/^\[\]/);
        if(hash!=null)
        {
            msg = msg.substring(2).trim();
            hash = null;
        }
    }

    var log = { t: Math.floor(d / 1000), m: msg };
    if (hash != null) { log.h = hash; }

    // Check for File/Line in generic log entry
    test = msg.match(/^.+:[0-9]+ \([0-9]+,[0-9]+\)/);
    if (test != null)
    {
        log.m = log.m.substring(test[0].length).trim();
        log.f = test[0].match(/^.+(?=:[0-9]+)/)[0];
        log.l = test[0].match(/(?!:)[0-9]+(?= \([0-9]+,[0-9]+\)$)/)[0];
    }

    this.results.push(log);
}

//
// This function will accumulate a raw data read from the file system, and attempt
// to parse the entries line by line
//
function readLog_data(buffer)
{
    var lines = buffer.toString();
    if (this.buffered != null) { lines = this.buffered + lines; }
    lines = lines.split('\n');
    var i;

    for (i = 0; i < (lines.length - 1) ; ++i)
    {
        parseLine.call(this, lines[i]);
    }

    if (lines.length == 1)
    {
        parseLine.call(this, lines[0]);
        this.buffered = null;
    }
    else
    {
        this.buffered = lines[lines.length - 1];
    }
}

//
// This function will attempt to read the Mesh Agent log specified by 'path'
// and return an array of log entries
//
function readLogEx(path)
{
    var ret = [];
    try
    {
        var s = require('fs').createReadStream(path);
        s.buffered = null;
        s.results = ret;
        s.on('data', readLog_data); 
        s.resume();
        if (s.buffered != null) { readLog_data.call(s, s.buffered); s.buffered = null; }
        s.removeAllListeners('data');
        s = null;
    }
    catch(z)
    {
    }

    return (ret);
}

//
// This function will attempt to read the Mesh Agent log specified by 'path'
// and return an array of log entries. 'criteria' can be the number of log entries to fetch, or a timestamp of the oldest entry to fetch
//
function readLog(criteria, path)
{
    var objects = readLogEx(path == null ? (process.execPath.split('.exe').join('') + '.log') : path);
    var ret = [];

    if (typeof (criteria) == 'string')
    {
        try
        {
            var dstring = Date.parse(criteria);
            criteria = Math.floor(dstring / 1000);
        }
        catch(z)
        {
        }
    }

    if (typeof (criteria) == 'number')
    {
        if(criteria < 1000)
        {
            // Return the last xxx entries
            ret = objects.slice(objects.length - ((criteria > objects.length) ? objects.length : criteria));
        }
        else
        {
            // Return entries that are newer than xxx
            var i;
            for (i = 0; i < objects.length && objects[i].t <= criteria; ++i) { }
            ret = objects.slice(i);
        }
    }
    else
    {
        ret = objects;
    }

    return (ret);
}

module.exports = { read: readLog, readEx: readLogEx }