package onvif

import (
	"encoding/xml"
	"errors"
	"io"
	"strings"
)

var ErrInvalidResponse = errors.New("ONVIF 返回内容无法识别")

type profileEnvelope struct {
	Profiles []struct {
		Token   string `xml:"token,attr"`
		Name    string `xml:"Name"`
		Encoder struct {
			Encoding   string `xml:"Encoding"`
			Resolution struct {
				Width  int `xml:"Width"`
				Height int `xml:"Height"`
			} `xml:"Resolution"`
		} `xml:"VideoEncoderConfiguration"`
	} `xml:"Body>GetProfilesResponse>Profiles"`
}

func parseProfiles(data []byte) ([]Profile, error) {
	var envelope profileEnvelope
	if err := xml.Unmarshal(data, &envelope); err != nil || len(envelope.Profiles) == 0 || len(envelope.Profiles) > 128 {
		return nil, ErrInvalidResponse
	}
	result := make([]Profile, 0, len(envelope.Profiles))
	for _, p := range envelope.Profiles {
		if strings.TrimSpace(p.Token) == "" || len(p.Token) > 255 || len([]rune(p.Name)) > 255 || p.Encoder.Resolution.Width <= 0 || p.Encoder.Resolution.Width > 32768 || p.Encoder.Resolution.Height <= 0 || p.Encoder.Resolution.Height > 32768 || len(p.Encoder.Encoding) > 32 {
			continue
		}
		result = append(result, Profile{Token: p.Token, Name: p.Name, Width: p.Encoder.Resolution.Width, Height: p.Encoder.Resolution.Height, Encoding: p.Encoder.Encoding})
	}
	if len(result) == 0 {
		return nil, ErrInvalidResponse
	}
	return result, nil
}

func parseElement(data []byte, parent, name string) (string, error) {
	decoder := xml.NewDecoder(strings.NewReader(string(data)))
	depth := 0
	for {
		token, err := decoder.Token()
		if err != nil {
			if errors.Is(err, io.EOF) {
				return "", ErrInvalidResponse
			}
			return "", ErrInvalidResponse
		}
		switch value := token.(type) {
		case xml.StartElement:
			if parent == "" || value.Name.Local == parent {
				if value.Name.Local == parent {
					depth++
				}
			}
			if (parent == "" || depth > 0) && value.Name.Local == name {
				var text string
				if err := decoder.DecodeElement(&text, &value); err != nil {
					return "", ErrInvalidResponse
				}
				return strings.TrimSpace(text), nil
			}
		case xml.EndElement:
			if value.Name.Local == parent && depth > 0 {
				depth--
			}
		}
	}
}