// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
//
// 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.

package ofdgo

import (
	"encoding/xml"
	"fmt"
)

// ofdCreator 标识本库生成的文档
const ofdCreator = "xiaoqidun/ofdgo"

// OFD OFD入口结构
// 代表OFD文档的根节点
type OFD struct {
	XMLName xml.Name  `xml:"OFD"`
	Version string    `xml:"Version,attr"`
	DocType string    `xml:"DocType,attr"`
	DocBody []DocBody `xml:"DocBody"`
}

// DocBody 文档体信息
// 包含文档元数据和根节点路径
type DocBody struct {
	DocInfo    DocInfo `xml:"DocInfo"`
	DocRoot    string  `xml:"DocRoot"`
	Signatures string  `xml:"Signatures"`
	versioned  bool
}

// DocInfo 文档元数据
type DocInfo struct {
	DocID          string       `xml:"DocID"`
	Title          string       `xml:"Title"`
	Author         string       `xml:"Author"`
	Subject        string       `xml:"Subject"`
	Abstract       string       `xml:"Abstract"`
	CreationDate   string       `xml:"CreationDate"`
	ModDate        string       `xml:"ModDate"`
	Creator        string       `xml:"Creator"`
	CreatorVersion string       `xml:"CreatorVersion"`
	CustomDatas    *CustomDatas `xml:"CustomDatas"`
}

// CustomDatas 自定义数据集合
type CustomDatas struct {
	CustomData []CustomData `xml:"CustomData"`
}

// CustomData 自定义数据项
type CustomData struct {
	Name        string `xml:"Name,attr"`
	Value       string `xml:",chardata"`
	sourceIndex int
}

// UnmarshalXML 读取主入口，区分标准文档条目与扩展中的同名节点
// 入参: decoder XML解码器, start 起始节点
// 返回: error 解析错误
func (ofd *OFD) UnmarshalXML(decoder *xml.Decoder, start xml.StartElement) error {
	if start.Name.Local != "OFD" {
		return fmt.Errorf("expected OFD root, got %s", start.Name.Local)
	}
	*ofd = OFD{XMLName: start.Name, Version: attrValue(start, "Version"), DocType: attrValue(start, "DocType")}
	return decodeOFDChildren(decoder, start, func(d *xml.Decoder, node xml.StartElement) error {
		if node.Name.Local != "DocBody" {
			return d.Skip()
		}
		var body DocBody
		if err := d.DecodeElement(&body, &node); err != nil {
			return err
		}
		ofd.DocBody = append(ofd.DocBody, body)
		return nil
	})
}

// UnmarshalXML 读取文档入口并记录版本列表是否存在，版本描述在选择时读取
// 入参: decoder XML解码器, start 起始节点
// 返回: error 解析错误
func (body *DocBody) UnmarshalXML(decoder *xml.Decoder, start xml.StartElement) error {
	*body = DocBody{}
	return decodeOFDChildren(decoder, start, func(d *xml.Decoder, node xml.StartElement) error {
		switch node.Name.Local {
		case "DocInfo":
			return d.DecodeElement(&body.DocInfo, &node)
		case "DocRoot":
			return d.DecodeElement(&body.DocRoot, &node)
		case "Signatures":
			return d.DecodeElement(&body.Signatures, &node)
		case "Versions":
			body.versioned = true
		}
		return d.Skip()
	})
}