package main

import (
	"encoding/json"
	"log"
	"net/http"
	"strings"
)

type Attendee struct {
	AttendeeId int64
	Name       string
}

type AttendeeList struct {
	Attendees *[]*Attendee `json:"attendees"`
}

func (a *Attendee) Write(w http.ResponseWriter) error {
	enc := json.NewEncoder(w)
	return enc.Encode(a)
}

func (a *Attendee) Read(json_str string) error {
	dec := json.NewDecoder(strings.NewReader(json_str))
	return dec.Decode(a)
}

func (al *AttendeeList) Write(w http.ResponseWriter) error {
	enc := json.NewEncoder(w)
	return enc.Encode(al)
}

type AttendeeExistsError struct{}

func (aeu AttendeeExistsError) Error() string {
	return "Attendee exists"
}

func GetAttendees() (*[]*Attendee, error) {
	var attendees []*Attendee

	_, err := DB.Select(&attendees, "SELECT * from attendees")
	if err != nil {
		return nil, err
	}
	return &attendees, nil
}

func InsertAttendee(a *Attendee) error {
	transaction, err := DB.Begin()
	if err != nil {
		return err
	}

	existing, err := transaction.SelectInt("SELECT count(*) from users where Name=?", a.Name)
	if err != nil {
		transaction.Rollback()
		return err
	}
	if existing > 0 {
		transaction.Rollback()
		return AttendeeExistsError{}
	}

	err = transaction.Insert(a)
	if err != nil {
		transaction.Rollback()
		return err
	}

	err = transaction.Commit()
	if err != nil {
		transaction.Rollback()
		return err
	}

	return nil
}

func AttendeeHandler(w http.ResponseWriter, r *http.Request) {
	_, err := GetUserFromSession(r)
	if err != nil {
		WriteError(w, 1 /*Not Signed In*/)
		return
	}

	if r.Method == "POST" {
		attendee_json := r.PostFormValue("attendee")
		if attendee_json == "" {
			WriteError(w, 3 /*Invalid Request*/)
			return
		}

		var attendee Attendee
		err := attendee.Read(attendee_json)
		if err != nil {
			WriteError(w, 3 /*Invalid Request*/)
			return
		}
		attendee.AttendeeId = -1

		err = InsertAttendee(&attendee)
		if err != nil {
			if _, ok := err.(AttendeeExistsError); ok {
				WriteError(w, 5 /*Attendee Exists*/)
			} else {
				WriteError(w, 999 /*Internal Error*/)
				log.Print(err)
			}
			return
		}

		w.WriteHeader(201 /*Created*/)
		err = attendee.Write(w)
		if err != nil {
			WriteError(w, 999 /*Internal Error*/)
			log.Print(err)
			return
		}
	} else if r.Method == "GET" {
		var al AttendeeList

		attendees, err := GetAttendees()
		if err != nil {
			WriteError(w, 999 /*Internal Error*/)
			log.Print(err)
			return
		}

		al.Attendees = attendees
		err = (&al).Write(w)
		if err != nil {
			WriteError(w, 999 /*Internal Error*/)
			log.Print(err)
			return
		}
	} else {
		/* No PUT or DELETE */
		WriteError(w, 3 /*Invalid Request*/)
		return
	}
}