package data

import (
  "os"
  "fmt"
  "log"
  "time"
  "strings"
  "strconv"
  "io/ioutil"

  "github.com/laurent22/ical-go/ical"

  "github.com/samedi/caldav-go/lib"
  "github.com/samedi/caldav-go/files"
)

type ResourceInterface interface {
  ComponentName() string
  StartTimeUTC() time.Time
  EndTimeUTC() time.Time
  Recurrences() []ResourceRecurrence
  HasProperty(propPath... string) bool
  GetPropertyValue(propPath... string) string
  HasPropertyParam(paramName... string) bool
  GetPropertyParamValue(paramName... string) string
}

type ResourceAdapter interface {
  IsCollection() bool
  CalculateEtag() string
  GetContent() string
  GetContentSize() int64
  GetModTime() time.Time
}

type ResourceRecurrence struct {
  StartTime time.Time
  EndTime   time.Time
}

type Resource struct {
  Name string
  Path string

  pathSplit []string
  adapter ResourceAdapter

  emptyTime time.Time
}

func NewResource(resPath string, adp ResourceAdapter) Resource {
  pClean  := lib.ToSlashPath(resPath)
  pSplit  := strings.Split(strings.Trim(pClean, "/"), "/")

  return Resource {
    Name: pSplit[len(pSplit) - 1],
    Path: pClean,
    pathSplit: pSplit,
    adapter: adp,
  }
}

func (r *Resource) IsCollection() bool {
  return r.adapter.IsCollection()
}

func (r *Resource) IsPrincipal() bool {
  return len(r.pathSplit) <= 1
}

func (r *Resource) ComponentName() string {
  if r.IsCollection() {
    return lib.VCALENDAR
  } else {
    return lib.VEVENT
  }
}

func (r *Resource) StartTimeUTC() time.Time {
  vevent := r.icalVEVENT()
  dtstart := vevent.PropDate(ical.DTSTART, r.emptyTime)

  if dtstart == r.emptyTime {
    log.Printf("WARNING: The property DTSTART was not found in the resource's ical data.\nResource path: %s", r.Path)
    return r.emptyTime
  }

  return dtstart.UTC()
}

func (r *Resource) EndTimeUTC() time.Time {
  vevent := r.icalVEVENT()
  dtend := vevent.PropDate(ical.DTEND, r.emptyTime)

  // when the DTEND property is not present, we just add the DURATION (if any) to the DTSTART
  if dtend == r.emptyTime {
    duration := vevent.PropDuration(ical.DURATION)
    dtend = r.StartTimeUTC().Add(duration)
  }

  return dtend.UTC()
}

func (r *Resource) Recurrences() []ResourceRecurrence {
  // TODO: Implement. This server does not support ical recurrences yet. We just return an empty array.
  return []ResourceRecurrence{}
}

func (r *Resource) HasProperty(propPath... string) bool {
  return r.GetPropertyValue(propPath...) != ""
}

func (r *Resource) GetPropertyValue(propPath... string) string {
  if propPath[0] == ical.VCALENDAR {
    propPath = propPath[1:]
  }

  prop, _ := r.icalendar().DigProperty(propPath...)
  return prop
}

func (r *Resource) HasPropertyParam(paramPath... string) bool {
  return r.GetPropertyParamValue(paramPath...) != ""
}

func (r *Resource) GetPropertyParamValue(paramPath... string) string {
  if paramPath[0] == ical.VCALENDAR {
    paramPath = paramPath[1:]
  }

  param, _ := r.icalendar().DigParameter(paramPath...)
  return param
}

func (r *Resource) GetEtag() (string, bool) {
  if r.IsCollection() {
    return "", false
  }

  return r.adapter.CalculateEtag(), true
}

func (r *Resource) GetContentType() (string, bool) {
  if r.IsCollection() {
    return "text/calendar", true
  } else {
    return "text/calendar; component=vcalendar", true
  }
}

func (r *Resource) GetDisplayName() (string, bool) {
   return r.Name, true
}

func (r *Resource) GetContentData() (string, bool) {
  data := r.adapter.GetContent()
  found := data != ""

  return data, found
}

func (r *Resource) GetContentLength() (string, bool) {
  // If its collection, it does not have any content, so mark it as not found
  if r.IsCollection() {
    return "", false
  }

  contentSize := r.adapter.GetContentSize()
  return strconv.FormatInt(contentSize, 10), true
}

func (r *Resource) GetLastModified(format string) (string, bool) {
  return r.adapter.GetModTime().Format(format), true
}

func (r *Resource) GetOwner() (string, bool) {
  var owner string
  if len(r.pathSplit) > 1 {
    owner = r.pathSplit[0]
  } else {
    owner = ""
  }

  return owner, true
}

func (r *Resource) GetOwnerPath() (string, bool) {
  owner, _ := r.GetOwner()

  if owner != "" {
    return fmt.Sprintf("/%s/", owner), true
  } else {
    return "", false
  }
}

// TODO: memoize
func (r *Resource) icalVEVENT() *ical.Node {
  vevent := r.icalendar().ChildByName(ical.VEVENT)

  // if nil, log it and return an empty vevent
  if vevent == nil {
    log.Printf("WARNING: The resource's ical data is missing the VEVENT property.\nResource path: %s", r.Path)

    return &ical.Node{
      Name: ical.VEVENT,
    }
  }

  return vevent
}

// TODO: memoize
func (r *Resource) icalendar() *ical.Node {
  data, found := r.GetContentData()

  if !found {
    log.Printf("WARNING: The resource's ical data does not have any data.\nResource path: %s", r.Path)
    return &ical.Node{
      Name: ical.VCALENDAR,
    }
  }

  icalNode, err := ical.ParseCalendar(data)
  if err != nil {
    log.Printf("ERROR: Could not parse the resource's ical data.\nError: %s.\nResource path: %s", err, r.Path)
    return &ical.Node{
      Name: ical.VCALENDAR,
    }
  }

  return icalNode
}

type FileResourceAdapter struct {
  finfo        os.FileInfo
  resourcePath string
}

func (adp *FileResourceAdapter) IsCollection() bool {
  return adp.finfo.IsDir()
}

func (adp *FileResourceAdapter) GetContent() string {
  if adp.IsCollection() {
    return ""
  }

  data, err := ioutil.ReadFile(files.AbsPath(adp.resourcePath))
  if err != nil {
    log.Printf("ERROR: Could not read file content for the resource.\nError: %s.\nResource path: %s.", err, adp.resourcePath)
    return ""
  }

  return string(data)
}

func (adp *FileResourceAdapter) GetContentSize() int64 {
  return adp.finfo.Size()
}

func (adp *FileResourceAdapter) CalculateEtag() string {
  // returns ETag as the concatenated hex values of a file's
	// modification time and size. This is not a reliable synchronization
	// mechanism for directories, so for collections we return empty.
  if adp.IsCollection() {
    return ""
  }

  fi := adp.finfo
  return fmt.Sprintf(`"%x%x"`, fi.ModTime().UnixNano(), fi.Size())
}

func (adp *FileResourceAdapter) GetModTime() time.Time {
  return adp.finfo.ModTime()
}