package internal

import (
	"encoding/xml"
	"fmt"
	"net/http"
	"strconv"
	"strings"
	"time"
)

const Namespace = "DAV:"

var (
	ResourceTypeName     = xml.Name{"DAV:", "resourcetype"}
	DisplayNameName      = xml.Name{"DAV:", "displayname"}
	GetContentLengthName = xml.Name{"DAV:", "getcontentlength"}
	GetContentTypeName   = xml.Name{"DAV:", "getcontenttype"}
	GetLastModifiedName  = xml.Name{"DAV:", "getlastmodified"}
	GetETagName          = xml.Name{"DAV:", "getetag"}

	CurrentUserPrincipalName = xml.Name{"DAV:", "current-user-principal"}
)

type Status struct {
	Code int
	Text string
}

func (s *Status) MarshalText() ([]byte, error) {
	text := s.Text
	if text == "" {
		text = http.StatusText(s.Code)
	}
	return []byte(fmt.Sprintf("HTTP/1.1 %v %v", s.Code, s.Text)), nil
}

func (s *Status) UnmarshalText(b []byte) error {
	if len(b) == 0 {
		return nil
	}

	parts := strings.SplitN(string(b), " ", 3)
	if len(parts) != 3 {
		return fmt.Errorf("webdav: invalid HTTP status %q: expected 3 fields", s)
	}
	code, err := strconv.Atoi(parts[1])
	if err != nil {
		return fmt.Errorf("webdav: invalid HTTP status %q: failed to parse code: %v", s, err)
	}

	s.Code = code
	s.Text = parts[2]
	return nil
}

func (s *Status) Err() error {
	if s == nil {
		return nil
	}

	// TODO: handle 2xx, 3xx
	if s.Code != http.StatusOK {
		return &HTTPError{Code: s.Code}
	}
	return nil
}

// https://tools.ietf.org/html/rfc4918#section-14.16
type Multistatus struct {
	XMLName             xml.Name   `xml:"DAV: multistatus"`
	Responses           []Response `xml:"response"`
	ResponseDescription string     `xml:"responsedescription,omitempty"`
}

func NewMultistatus(resps ...Response) *Multistatus {
	return &Multistatus{Responses: resps}
}

func (ms *Multistatus) Get(href string) (*Response, error) {
	for i := range ms.Responses {
		resp := &ms.Responses[i]
		for _, h := range resp.Hrefs {
			if h == href {
				return resp, resp.Status.Err()
			}
		}
	}

	return nil, fmt.Errorf("webdav: missing response for href %q", href)
}

// https://tools.ietf.org/html/rfc4918#section-14.24
type Response struct {
	XMLName             xml.Name   `xml:"DAV: response"`
	Hrefs               []string   `xml:"href"`
	Propstats           []Propstat `xml:"propstat,omitempty"`
	ResponseDescription string     `xml:"responsedescription,omitempty"`
	Status              *Status    `xml:"status,omitempty"`
	Error               *Error     `xml:"error,omitempty"`
	Location            *Location  `xml:"location,omitempty"`
}

func NewOKResponse(href string) *Response {
	return &Response{
		Hrefs:  []string{href},
		Status: &Status{Code: http.StatusOK},
	}
}

func (resp *Response) Href() (string, error) {
	if err := resp.Status.Err(); err != nil {
		return "", err
	}
	if len(resp.Hrefs) != 1 {
		return "", fmt.Errorf("webdav: malformed response: expected exactly one href element, got %v", len(resp.Hrefs))
	}
	return resp.Hrefs[0], nil
}

type missingPropError struct {
	XMLName xml.Name
}

func (err *missingPropError) Error() string {
	return fmt.Sprintf("webdav: missing prop %q %q", err.XMLName.Space, err.XMLName.Local)
}

func IsMissingProp(err error) bool {
	_, ok := err.(*missingPropError)
	return ok
}

func (resp *Response) DecodeProp(values ...interface{}) error {
	for _, v := range values {
		// TODO wrap errors with more context (XML name)
		name, err := valueXMLName(v)
		if err != nil {
			return err
		}
		if err := resp.Status.Err(); err != nil {
			return err
		}
		for _, propstat := range resp.Propstats {
			raw := propstat.Prop.Get(name)
			if raw == nil {
				continue
			}
			if err := propstat.Status.Err(); err != nil {
				return err
			}
			return raw.Decode(v)
		}
		return &missingPropError{name}
	}

	return nil
}

func (resp *Response) EncodeProp(code int, v interface{}) error {
	raw, err := EncodeRawXMLElement(v)
	if err != nil {
		return err
	}

	for i := range resp.Propstats {
		propstat := &resp.Propstats[i]
		if propstat.Status.Code == code {
			propstat.Prop.Raw = append(propstat.Prop.Raw, *raw)
			return nil
		}
	}

	resp.Propstats = append(resp.Propstats, Propstat{
		Status: Status{Code: code},
		Prop:   Prop{Raw: []RawXMLValue{*raw}},
	})
	return nil
}

// https://tools.ietf.org/html/rfc4918#section-14.9
type Location struct {
	XMLName xml.Name `xml:"DAV: location"`
	Href    string   `xml:"href"`
}

// https://tools.ietf.org/html/rfc4918#section-14.22
type Propstat struct {
	XMLName             xml.Name `xml:"DAV: propstat"`
	Prop                Prop     `xml:"prop"`
	Status              Status   `xml:"status"`
	ResponseDescription string   `xml:"responsedescription,omitempty"`
	Error               *Error   `xml:"error,omitempty"`
}

// https://tools.ietf.org/html/rfc4918#section-14.18
type Prop struct {
	XMLName xml.Name      `xml:"DAV: prop"`
	Raw     []RawXMLValue `xml:",any"`
}

func EncodeProp(values ...interface{}) (*Prop, error) {
	l := make([]RawXMLValue, len(values))
	for i, v := range values {
		raw, err := EncodeRawXMLElement(v)
		if err != nil {
			return nil, err
		}
		l[i] = *raw
	}
	return &Prop{Raw: l}, nil
}

func (p *Prop) Get(name xml.Name) *RawXMLValue {
	for i := range p.Raw {
		raw := &p.Raw[i]
		if n, ok := raw.XMLName(); ok && name == n {
			return raw
		}
	}
	return nil
}

func (p *Prop) Decode(v interface{}) error {
	name, err := valueXMLName(v)
	if err != nil {
		return err
	}

	raw := p.Get(name)
	if raw == nil {
		return &missingPropError{name}
	}

	return raw.Decode(v)
}

// https://tools.ietf.org/html/rfc4918#section-14.20
type Propfind struct {
	XMLName  xml.Name  `xml:"DAV: propfind"`
	Prop     *Prop     `xml:"prop,omitempty"`
	AllProp  *struct{} `xml:"allprop,omitempty"`
	Include  *Include  `xml:"include,omitempty"`
	PropName *struct{} `xml:"propname,omitempty"`
}

func xmlNamesToRaw(names []xml.Name) []RawXMLValue {
	l := make([]RawXMLValue, len(names))
	for i, name := range names {
		l[i] = *NewRawXMLElement(name, nil, nil)
	}
	return l
}

func NewPropNamePropfind(names ...xml.Name) *Propfind {
	return &Propfind{Prop: &Prop{Raw: xmlNamesToRaw(names)}}
}

// https://tools.ietf.org/html/rfc4918#section-14.8
type Include struct {
	XMLName xml.Name      `xml:"DAV: include"`
	Raw     []RawXMLValue `xml:",any"`
}

// https://tools.ietf.org/html/rfc4918#section-15.9
type ResourceType struct {
	XMLName xml.Name      `xml:"DAV: resourcetype"`
	Raw     []RawXMLValue `xml:",any"`
}

func NewResourceType(names ...xml.Name) *ResourceType {
	return &ResourceType{Raw: xmlNamesToRaw(names)}
}

func (t *ResourceType) Is(name xml.Name) bool {
	for _, raw := range t.Raw {
		if n, ok := raw.XMLName(); ok && name == n {
			return true
		}
	}
	return false
}

var CollectionName = xml.Name{"DAV:", "collection"}

// https://tools.ietf.org/html/rfc4918#section-15.4
type GetContentLength struct {
	XMLName xml.Name `xml:"DAV: getcontentlength"`
	Length  int64    `xml:",chardata"`
}

// https://tools.ietf.org/html/rfc4918#section-15.5
type GetContentType struct {
	XMLName xml.Name `xml:"DAV: getcontenttype"`
	Type    string   `xml:",chardata"`
}

type Time time.Time

func (t *Time) UnmarshalText(b []byte) error {
	tt, err := http.ParseTime(string(b))
	if err != nil {
		return err
	}
	*t = Time(tt)
	return nil
}

func (t *Time) MarshalText() ([]byte, error) {
	s := time.Time(*t).Format(time.RFC1123Z)
	return []byte(s), nil
}

// https://tools.ietf.org/html/rfc4918#section-15.7
type GetLastModified struct {
	XMLName      xml.Name `xml:"DAV: getlastmodified"`
	LastModified Time     `xml:",chardata"`
}

// https://tools.ietf.org/html/rfc4918#section-14.5
type Error struct {
	XMLName xml.Name      `xml:"DAV: error"`
	Raw     []RawXMLValue `xml:",any"`
}

// https://tools.ietf.org/html/rfc4918#section-15.2
type DisplayName struct {
	XMLName xml.Name `xml:"DAV: displayname"`
	Name    string   `xml:",chardata"`
}

// https://tools.ietf.org/html/rfc5397#section-3
type CurrentUserPrincipal struct {
	XMLName         xml.Name  `xml:"DAV: current-user-principal"`
	Href            string    `xml:"href,omitempty"`
	Unauthenticated *struct{} `xml:"unauthenticated,omitempty"`
}