/**
 * CSV 匯入匯出模組
 * 處理各表單的 CSV 資料交換
 */

const API_BASE_URL = '/api';

// ==================== CSV 工具函數 ====================

export const CSVUtils = {
    /**
     * 匯出資料到 CSV
     */
    exportToCSV(data, filename, headers) {
        if (!data || data.length === 0) {
            console.warn('No data to export');
            return;
        }

        const csvHeaders = headers || Object.keys(data[0]);
        const csvRows = data.map(row => {
            return csvHeaders.map(header => {
                let value = row[header] !== undefined ? row[header] : '';
                // 處理包含逗號或換行的值
                if (typeof value === 'string' && (value.includes(',') || value.includes('\n') || value.includes('"'))) {
                    value = '"' + value.replace(/"/g, '""') + '"';
                }
                return value;
            }).join(',');
        });

        const csvContent = '\uFEFF' + [csvHeaders.join(','), ...csvRows].join('\n'); // BOM for UTF-8
        const blob = new Blob([csvContent], { type: 'text/csv;charset=utf-8;' });
        const link = document.createElement('a');
        link.href = URL.createObjectURL(blob);
        link.download = filename;
        link.click();
    },

    /**
     * 從 CSV 匯入資料
     */
    importFromCSV(file, callback) {
        const reader = new FileReader();
        reader.onload = (e) => {
            const text = e.target.result;
            const lines = text.split('\n').filter(line => line.trim());
            if (lines.length < 2) {
                callback([]);
                return;
            }

            const headers = this.parseCSVLine(lines[0]);
            const data = [];

            for (let i = 1; i < lines.length; i++) {
                const values = this.parseCSVLine(lines[i]);
                const row = {};
                headers.forEach((header, index) => {
                    row[header.trim()] = values[index] ? values[index].trim() : '';
                });
                data.push(row);
            }

            callback(data);
        };
        reader.readAsText(file, 'UTF-8');
    },

    /**
     * 解析 CSV 行（處理引號內的逗號）
     */
    parseCSVLine(line) {
        const result = [];
        let current = '';
        let inQuotes = false;

        for (let i = 0; i < line.length; i++) {
            const char = line[i];
            if (char === '"') {
                if (inQuotes && line[i + 1] === '"') {
                    current += '"';
                    i++;
                } else {
                    inQuotes = !inQuotes;
                }
            } else if (char === ',' && !inQuotes) {
                result.push(current);
                current = '';
            } else {
                current += char;
            }
        }
        result.push(current);
        return result;
    }
};

// ==================== 崗位資料 CSV ====================

export function downloadPositionCSVTemplate() {
    window.location.href = API_BASE_URL + '/positions/csv-template';
    if (typeof showToast === 'function') showToast('正在下載崗位資料範本...');
}

export function exportPositionsCSV() {
    const data = [{
        positionCode: getFieldValue('positionCode'),
        positionName: getFieldValue('positionName'),
        positionCategory: getFieldValue('positionCategory'),
        positionNature: getFieldValue('positionNature'),
        headcount: getFieldValue('headcount'),
        positionLevel: getFieldValue('positionLevel'),
        effectiveDate: getFieldValue('effectiveDate'),
        positionDesc: getFieldValue('positionDesc'),
        positionRemark: getFieldValue('positionRemark'),
        minEducation: getFieldValue('minEducation'),
        salaryRange: getFieldValue('salaryRange'),
        workExperience: getFieldValue('workExperience'),
        minAge: getFieldValue('minAge'),
        maxAge: getFieldValue('maxAge')
    }];

    const headers = ['positionCode', 'positionName', 'positionCategory', 'positionNature',
                   'headcount', 'positionLevel', 'effectiveDate', 'positionDesc', 'positionRemark',
                   'minEducation', 'salaryRange', 'workExperience', 'minAge', 'maxAge'];

    CSVUtils.exportToCSV(data, 'positions.csv', headers);
    if (typeof showToast === 'function') showToast('崗位資料已匯出！');
}

export function importPositionsCSV() {
    document.getElementById('positionCSVInput').click();
}

export function handlePositionCSVImport(event) {
    const file = event.target.files[0];
    if (!file) return;

    const formData = new FormData();
    formData.append('file', file);

    if (typeof showToast === 'function') showToast('正在匯入崗位資料...');

    fetch(API_BASE_URL + '/positions/import-csv', {
        method: 'POST',
        body: formData
    })
    .then(response => response.json())
    .then(data => {
        if (data.success) {
            let message = data.message;
            if (data.errors && data.errors.length > 0) {
                message += '\n\n錯誤詳情:\n' + data.errors.join('\n');
            }
            alert(message);
        } else {
            alert('匯入失敗: ' + (data.error || '未知錯誤'));
        }
    })
    .catch(error => {
        console.error('匯入錯誤:', error);
        alert('匯入失敗: ' + error.message);
    })
    .finally(() => {
        event.target.value = '';
    });
}

// ==================== 職務資料 CSV ====================

export function downloadJobCSVTemplate() {
    window.location.href = API_BASE_URL + '/jobs/csv-template';
    if (typeof showToast === 'function') showToast('正在下載職務資料範本...');
}

export function exportJobsCSV() {
    const data = [{
        jobCategoryCode: getFieldValue('jobCategoryCode'),
        jobCategoryName: getFieldValue('jobCategoryName'),
        jobCode: getFieldValue('jobCode'),
        jobName: getFieldValue('jobName'),
        jobNameEn: getFieldValue('jobNameEn'),
        jobEffectiveDate: getFieldValue('jobEffectiveDate'),
        jobHeadcount: getFieldValue('jobHeadcount'),
        jobSortOrder: getFieldValue('jobSortOrder'),
        jobRemark: getFieldValue('jobRemark'),
        jobLevel: getFieldValue('jobLevel'),
        hasAttendanceBonus: document.getElementById('job_hasAttBonus')?.checked,
        hasHousingAllowance: document.getElementById('job_hasHouseAllow')?.checked
    }];

    const headers = ['jobCategoryCode', 'jobCategoryName', 'jobCode', 'jobName', 'jobNameEn',
                   'jobEffectiveDate', 'jobHeadcount', 'jobSortOrder', 'jobRemark', 'jobLevel',
                   'hasAttendanceBonus', 'hasHousingAllowance'];

    CSVUtils.exportToCSV(data, 'jobs.csv', headers);
    if (typeof showToast === 'function') showToast('職務資料已匯出！');
}

export function importJobsCSV() {
    document.getElementById('jobCSVInput').click();
}

export function handleJobCSVImport(event) {
    const file = event.target.files[0];
    if (!file) return;

    const formData = new FormData();
    formData.append('file', file);

    if (typeof showToast === 'function') showToast('正在匯入職務資料...');

    fetch(API_BASE_URL + '/jobs/import-csv', {
        method: 'POST',
        body: formData
    })
    .then(response => response.json())
    .then(data => {
        if (data.success) {
            let message = data.message;
            if (data.errors && data.errors.length > 0) {
                message += '\n\n錯誤詳情:\n' + data.errors.join('\n');
            }
            alert(message);
        } else {
            alert('匯入失敗: ' + (data.error || '未知錯誤'));
        }
    })
    .catch(error => {
        console.error('匯入錯誤:', error);
        alert('匯入失敗: ' + error.message);
    })
    .finally(() => {
        event.target.value = '';
    });
}

// ==================== 崗位描述 CSV ====================

export function exportDescriptionsCSV() {
    const data = [{
        descPositionCode: getFieldValue('descPositionCode'),
        descPositionName: getFieldValue('descPositionName'),
        descEffectiveDate: getFieldValue('descEffectiveDate'),
        jobDuties: getFieldValue('jobDuties'),
        requiredSkills: getFieldValue('requiredSkills'),
        workEnvironment: getFieldValue('workEnvironment'),
        careerPath: getFieldValue('careerPath'),
        descRemark: getFieldValue('descRemark')
    }];

    const headers = ['descPositionCode', 'descPositionName', 'descEffectiveDate', 'jobDuties',
                   'requiredSkills', 'workEnvironment', 'careerPath', 'descRemark'];

    CSVUtils.exportToCSV(data, 'job_descriptions.csv', headers);
    if (typeof showToast === 'function') showToast('崗位描述已匯出！');
}

export function importDescriptionsCSV() {
    document.getElementById('descCSVInput').click();
}

export function handleDescCSVImport(event) {
    const file = event.target.files[0];
    if (!file) return;

    CSVUtils.importFromCSV(file, (data) => {
        if (data && data.length > 0) {
            const firstRow = data[0];
            Object.keys(firstRow).forEach(key => {
                const element = document.getElementById(key);
                if (element) {
                    element.value = firstRow[key];
                }
            });
            if (typeof showToast === 'function') {
                showToast(`已匯入 ${data.length} 筆崗位描述資料（顯示第一筆）`);
            }
        }
    });
    event.target.value = '';
}

// ==================== 崗位清單 CSV ====================

export function exportPositionListCSV(positionListData) {
    if (!positionListData || positionListData.length === 0) {
        if (typeof showToast === 'function') showToast('請先載入清單資料');
        return;
    }
    const headers = ['positionCode', 'positionName', 'businessUnit', 'department', 'positionCategory', 'headcount', 'effectiveDate'];
    CSVUtils.exportToCSV(positionListData, 'position_list.csv', headers);
    if (typeof showToast === 'function') showToast('崗位清單已匯出！');
}

// ==================== 部門職責 CSV ====================

export function importDeptFunctionCSV() {
    document.getElementById('deptFunctionCsvInput').click();
}

export function handleDeptFunctionCSVImport(event, callback) {
    const file = event.target.files[0];
    if (!file) return;

    CSVUtils.importFromCSV(file, (data) => {
        if (data && data.length > 0) {
            const row = data[0];
            Object.keys(row).forEach(key => {
                const el = document.getElementById(key);
                if (el) el.value = row[key];
            });
            if (typeof showToast === 'function') showToast('已匯入 CSV 資料！');
            if (callback) callback(data);
        }
    });
    event.target.value = '';
}

export function exportDeptFunctionCSV(formData) {
    const headers = Object.keys(formData);
    CSVUtils.exportToCSV([formData], 'dept_function.csv', headers);
    if (typeof showToast === 'function') showToast('部門職責資料已匯出！');
}

// ==================== 工具函數 ====================

function getFieldValue(elementId) {
    const el = document.getElementById(elementId);
    return el ? el.value.trim() : '';
}

// 暴露到全域
if (typeof window !== 'undefined') {
    window.CSVUtils = CSVUtils;
}