Cron表达式解析器

功能1：解析Cron表达式

请输入6位格式的Cron表达式（秒 分 时 日 月 周）：

<div id="cronResult"></div>

<h2>功能2：生成Cron表达式</h2>
<p>请选择运行时间：</p>
<input type="checkbox" id="secondCheckbox" onchange="generateCronExpression()">秒
<input type="checkbox" id="minuteCheckbox" onchange="generateCronExpression()">分
<input type="checkbox" id="hourCheckbox" onchange="generateCronExpression()">时
<input type="checkbox" id="dayCheckbox" onchange="generateCronExpression()">日
<input type="checkbox" id="monthCheckbox" onchange="generateCronExpression()">月
<input type="checkbox" id="weekCheckbox" onchange="generateCronExpression()">周

<div id="generatedCronExpression"></div>

<script>
    function parseCron() {
        const cronExpression = document.getElementById("cronExpression").value;
        const cronResult = document.getElementById("cronResult");

        if (!cronExpression) {
            cronResult.innerHTML = "<p>请输入Cron表达式</p>";
            return;
        }

        const cronParts = cronExpression.split(" ");
        if (cronParts.length !== 6) {
            cronResult.innerHTML = "<p>请输入正确的Cron表达式</p>";
            return;
        }

        const second = cronParts[0];
        const minute = cronParts[1];
        const hour = cronParts[2];
        const day = cronParts[3];
        const month = cronParts[4];
        const week = cronParts[5];

        const date1 = new Date();
        const date2 = new Date();
        const date3 = new Date();
        const date4 = new Date();
        const date5 = new Date();
        const date6 = new Date();

        date1.setSeconds(date1.getSeconds() + getNext(second));
        date2.setMinutes(date2.getMinutes() + getNext(minute));
        date3.setHours(date3.getHours() + getNext(hour));
        date4.setDate(date4.getDate() + getNext(day));
        date5.setMonth(date5.getMonth() + getNext(month));
        date6.setDate(date6.getDate() + getNextWeekday(week));

        cronResult.innerHTML = `
            <p>下一次运行时间：</p>
            <p>${date1}</p>
            <p>${date2}</p>
            <p>${date3}</p>
            <p>${date4}</p>
            <p>${date5}</p>
            <p>${date6}</p>
        `;
    }

    function getNext(expression) {
        const now = new Date();
        const currentValue = parseInt(now.getSeconds());

        const values = expression.split(",");
        for (let i = 0; i < values.length; i++) {
            const value = values[i];

            if (value === "*") {
                return 0;
            }

            if (value.includes("/")) {
                const step = parseInt(value.split("/")[1]);
                if (currentValue % step === 0) {
                    return 0;
                }
            }

            if (value.includes("-")) {
                const rangeValues = value.split("-");
                const minValue = parseInt(rangeValues[0]);
                const maxValue = parseInt(rangeValues[1]);
                if (currentValue >= minValue && currentValue <= maxValue) {
                    return 0;
                }
            }

            if (value === currentValue.toString()) {
                return 0;
            }

            if (value === "?") {
                return 0;
            }

            if (value === "L") {
                return -1;
            }

            if (value.includes("W")) {
                const dayOfMonth = parseInt(value.replace("W", ""));
                const lastDayOfMonth = new Date(now.getFullYear(), now.getMonth() + 1, 0).getDate();
                const weekday = new Date(now.getFullYear(), now.getMonth(), dayOfMonth).getDay();
                if (dayOfMonth < lastDayOfMonth && (weekday === 0 || weekday === 6)) {
                    return 0;
                } else if (dayOfMonth === lastDayOfMonth && weekday === 6) {
                    return -2;
                } else if (dayOfMonth === lastDayOfMonth && weekday !== 6) {
                    return -1;
                } else {
                    const nextWeekday = getNextWeekday("1-5");
                    const nextDate = new Date(now.getFullYear(), now.getMonth(), dayOfMonth + nextWeekday);
                    return nextDate.getSeconds() - now.getSeconds();
                }
            }

            if (value.includes("#")) {
                const dayOfWeek = value.split("#")[0];
                const occurrence = parseInt(value.split("#")[1]);
                const currentWeekday = now.getDay();
                let diff;
                if (currentWeekday > dayOfWeek) {
                    diff = 7 - currentWeekday + dayOfWeek;
                } else if (currentWeekday < dayOfWeek) {
                    diff = dayOfWeek - currentWeekday;
                } else {
                    if (now.getHours() === 0 && now.getMinutes() === 0 && now.getSeconds() < occurrence * 60) {
                        return occurrence * 60 - now.getSeconds();
                    } else {
                        diff = 0;
                    }
                }
                const nextDate = new Date(now.getFullYear(), now.getMonth(), now.getDate() + diff);
                return (occurrence - 1) * 7 * 24 * 60 * 60 + nextDate.getSeconds() - now.getSeconds();
            }
        }

        return -1;
    }

    function getNextWeekday(expression) {
        const now = new Date();
        const currentValue = now.getDay();

        const values = expression.split(",");
        for (let i = 0; i < values.length; i++) {
            const value = values[i];

            if (value === "*") {
                return 0;
            }

            if (value.includes("/")) {
                const step = parseInt(value.split("/")[1]);
                if (currentValue % step === 0) {
                    return 0;
                }
            }

            if (value.includes("-")) {
                const rangeValues = value.split("-");
                const minValue = parseInt(rangeValues[0]);
                const maxValue = parseInt(rangeValues[1]);
                if (currentValue >= minValue && currentValue <= maxValue) {
                    return 0;
                }
            }

            if (value === currentValue.toString()) {
                return 0;
            }

            if (value === "?") {
                return 0;
            }

            if (value === "L") {
                return -1;
            }

            if (value === "1") {
                return currentValue === 0 ? 1 : 8 - currentValue;
            }

            if (value === "2") {
                return currentValue === 0 ? 2 : 9 - currentValue;
            }

            if (value === "3") {
                return currentValue === 0 ? 3 : 10 - currentValue;
            }

            if (value === "4") {
                return currentValue === 0 ? 4 : 11 - currentValue;
            }

            if (value === "5") {
                return currentValue === 0 ? 5 : 12 - currentValue;
            }

            if (value === "6") {
                return currentValue === 0 ? 6 : 13 - currentValue;
            }

            if (value === "7") {
                return currentValue === 0 ? 7 : 14 - currentValue;
            }

            if (value.includes("W")) {
                const dayOfMonth = parseInt(value.replace("W", ""));
                const lastDayOfMonth = new Date(now.getFullYear(), now.getMonth() + 1, 0).getDate();
                const weekday = new Date(now.getFullYear(), now.getMonth(), dayOfMonth).getDay();
                if (dayOfMonth < lastDayOfMonth && (weekday === 0 || weekday === 6)) {
                    return 1;
                } else if (dayOfMonth === lastDayOfMonth && weekday === 6) {
                    return -1;
                } else if (dayOfMonth === lastDayOfMonth && weekday !== 6) {
                    return -2;
                } else {
                    return weekday - currentValue >= 0 ? weekday - currentValue : 7 - currentValue + weekday;
                }
            }
        }

        return -1;
    }

    function generateCronExpression() {
        const secondCheckbox = document.getElementById("secondCheckbox");
        const minuteCheckbox = document.getElementById("minuteCheckbox");
        const hourCheckbox = document.getElementById("hourCheckbox");
        const dayCheckbox = document.getElementById("dayCheckbox");
        const monthCheckbox = document.getElementById("monthCheckbox");
        const weekCheckbox = document.getElementById("weekCheckbox");

        let cronExpression = "";
        cronExpression += secondCheckbox.checked ? "*" : "0";
        cronExpression += " ";
        cronExpression += minuteCheckbox.checked ? "*" : "0";
        cronExpression += " ";
        cronExpression += hourCheckbox.checked ? "*" : "0";
        cronExpression += " ";
        cronExpression += dayCheckbox.checked ? "*" : "?";
        cronExpression += " ";
        cronExpression += monthCheckbox.checked ? "*" : "1";
        cronExpression += " ";
        cronExpression += weekCheckbox.checked ? "?" : "*";

        const generatedCronExpression = document.getElementById("generatedCronExpression");
        generatedCronExpression.innerHTML = `
            <p>生成的Cron表达式：</p>
            <p>${cronExpression}</p>
        `;
    }
</script>