/**
 * base64加密
 */
var Base64 = {
	_keyStr: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",
	encode: function(e) {
		var t = "";
		var n, r, i, s, o, u, a;
		var f = 0;
		e = Base64._utf8_encode(e);
		while (f < e.length) {
			n = e.charCodeAt(f++);
			r = e.charCodeAt(f++);
			i = e.charCodeAt(f++);
			s = n >> 2;
			o = (n & 3) << 4 | r >> 4;
			u = (r & 15) << 2 | i >> 6;
			a = i & 63;
			if (isNaN(r)) {
				u = a = 64
			} else if (isNaN(i)) {
				a = 64
			}
			t = t + this._keyStr.charAt(s) + this._keyStr.charAt(o) + this._keyStr.charAt(u) + this._keyStr
				.charAt(a)
		}
		return t
	},
	decode: function(e) {
		var t = "";
		var n, r, i;
		var s, o, u, a;
		var f = 0;
		e = e.replace(/[^A-Za-z0-9+/=]/g, "");
		while (f < e.length) {
			s = this._keyStr.indexOf(e.charAt(f++));
			o = this._keyStr.indexOf(e.charAt(f++));
			u = this._keyStr.indexOf(e.charAt(f++));
			a = this._keyStr.indexOf(e.charAt(f++));
			n = s << 2 | o >> 4;
			r = (o & 15) << 4 | u >> 2;
			i = (u & 3) << 6 | a;
			t = t + String.fromCharCode(n);
			if (u != 64) {
				t = t + String.fromCharCode(r)
			}
			if (a != 64) {
				t = t + String.fromCharCode(i)
			}
		}
		t = Base64._utf8_decode(t);
		return t
	},
	_utf8_encode: function(e) {
		e = e.replace(/rn/g, "n");
		var t = "";
		for (var n = 0; n < e.length; n++) {
			var r = e.charCodeAt(n);
			if (r < 128) {
				t += String.fromCharCode(r)
			} else if (r > 127 && r < 2048) {
				t += String.fromCharCode(r >> 6 | 192);
				t += String.fromCharCode(r & 63 | 128)
			} else {
				t += String.fromCharCode(r >> 12 | 224);
				t += String.fromCharCode(r >> 6 & 63 | 128);
				t += String.fromCharCode(r & 63 | 128)
			}
		}
		return t
	},
	_utf8_decode: function(e) {
		var t = "";
		var n = 0;
		var r = c1 = c2 = 0;
		while (n < e.length) {
			r = e.charCodeAt(n);
			if (r < 128) {
				t += String.fromCharCode(r);
				n++
			} else if (r > 191 && r < 224) {
				c2 = e.charCodeAt(n + 1);
				t += String.fromCharCode((r & 31) << 6 | c2 & 63);
				n += 2
			} else {
				c2 = e.charCodeAt(n + 1);
				c3 = e.charCodeAt(n + 2);
				t += String.fromCharCode((r & 15) << 12 | (c2 & 63) << 6 | c3 & 63);
				n += 3
			}
		}
		return t
	},
}

/**
 * 表单对象赋值:
 * 对目标对象存在且源对象同样存在的属性，全部覆盖；
 * 目标对象不存在但是源对象存在的属性， 全部丢弃；
 * 目标对象存在但是源对象不存在的属性，如果是字符串赋值为空串，其余类型赋值为undefined
 */
function recover(target, source) {
	if (target === undefined || target === null) {
		throw new TypeError('Cannot convert first argument to object')
	}
	var to = Object(target)
	if (source === undefined || source === null) {
		return to
	}
	var keysArray = Object.keys(Object(target))
	for (var nextIndex = 0, len = keysArray.length; nextIndex < len; nextIndex++) {
		var nextKey = keysArray[nextIndex]
		var desc = Object.getOwnPropertyDescriptor(target, nextKey)
		if (desc !== undefined && desc.enumerable) {
			if (to.hasOwnProperty(nextKey)) {
				if (to[nextKey] instanceof Array) {
					to[nextKey] = source[nextKey]
				} else if (to[nextKey] instanceof Object) {
					recover(to[nextKey], source[nextKey])
				} else if (source[nextKey] !== undefined) {
					to[nextKey] = source[nextKey]
				} else if (typeof(to[nextKey]) === 'string') {
					to[nextKey] = ''
				} else {
					to[nextKey] = undefined
				}
			}
		}
	}
	return to
}

/**
 * 表单对象赋值:
 * 对目标对象存在且源对象同样存在的属性，全部覆盖；
 * 目标对象不存在但是源对象存在的属性， 全部丢弃；
 * 目标对象存在但是源对象不存在的属性，保留目标对象的属性不做处理
 */
function recoverNotNull(target, source) {
	if (target === undefined || target === null) {
		throw new TypeError('Cannot convert first argument to object')
	}
	var to = Object(target)
	if (source === undefined || source === null) {
		return to
	}
	var keysArray = Object.keys(Object(target))
	for (var nextIndex = 0, len = keysArray.length; nextIndex < len; nextIndex++) {
		var nextKey = keysArray[nextIndex]
		var desc = Object.getOwnPropertyDescriptor(target, nextKey)
		if (desc !== undefined && desc.enumerable) {
			if (to.hasOwnProperty(nextKey)) {
				if (to[nextKey] instanceof Array) {
					to[nextKey] = source[nextKey]
				} else if (to[nextKey] instanceof Object) {
					recover(to[nextKey], source[nextKey])
				} else if (source[nextKey] !== undefined) {
					to[nextKey] = source[nextKey]
				}
			}
		}
	}
	return to
}

// 驼峰转下划线
function toLine(name) {
	if (name.indexOf('.') < 0) {
		return name.replace(/([A-Z])/g, '_$1').toLowerCase()
	} else {
		return name
	}
}
// 使用正则表达式判断文件名或URL是否为图片格式
function isImageFormat(filename) {
	const imageFormats = /\.(jpeg|jpg|gif|png|bmp|svg)$/i;
	return imageFormats.test(filename);
}

module.exports = {
	Base64: Base64,
	recover: recover,
	recoverNotNull: recoverNotNull,
	toLine: toLine,
	isImageFormat: isImageFormat,
}