<?php
/**
 * Created by Weiler.
 * User: Weiler
 * Email: weiler.china@gmail.com
 * Date: 2018/8/6
 */

function tailWithFile($filepath, $limit, $seek = 0)
{
    // 检测文件是否存在
    if (file_exists($filepath)) {
        // open file
        $f = @fopen($filepath, "rb");

        if ($seek > 0) {
            // 设置指针位置
            fseek($f, $seek, SEEK_SET);
        } else {
            // 指针移动到最后一个
            fseek($f, -1, SEEK_END);
            while ($limit > 0) {
                if (ftell($f) === 0)
                    break;
                if (fread($f, 1) == "\n") {
                    $limit--;
                }
                fseek($f, $limit === 0 ? -1 : -2, SEEK_CUR);
            }
        }

        $logArr = [];
        while(!feof($f))
        {
            $line = fgets($f);
            if ($line)
                array_push($logArr, $line);
        }
        $offset = ftell($f);
        fclose($f);
        return [
            'logArr'    =>  $logArr,
            'offset'    =>  $offset
        ];
    } else {
        return false;
    }
}
if (isset($_GET['filePath']) && is_string($_GET['filePath']) && isset($_GET['offset']) && is_numeric($_GET['offset'])) {
    $filepath = $_GET['filePath'];
    $offset = (int)$_GET['offset'];
    $tail = tailWithFile($filepath, 10, $offset);
    if ($tail) {
        echo json_encode([
            'code'  =>  200,
            'msg'   =>  '文件读取成功',
            'data'  =>  [
                'offset'    =>  $tail['offset'],
                'logArr'    =>  $tail['logArr']
            ]
        ]);
    } else {
        echo json_encode([
            'code'  =>  400,
            'msg'   =>  '文件读取错误或文件不存在'
        ]);
    }
} else {
    echo json_encode([
        'code'  =>  400,
        'msg'   =>  '请填写文件路径'
    ]);
}