package main

import (
	"crypto/hmac"
	"crypto/sha512"
	"encoding/json"
	"fmt"
	"strings"
	"time"

	"github.com/julienschmidt/httprouter"
)

func init() {
	router.GET("/api/progress/", apiHandler(
		func(httprouter.Params, []byte) (interface{}, error) {
			if stds, err := getStudents(); err != nil {
				return nil, err
			} else {
				ret := map[string]map[string]UnlockedChallenge{}
				for _, std := range stds {
					if sts, err := std.getStates(); err == nil {
						ret[std.Login] = map[string]UnlockedChallenge{}

						for _, s := range sts {
							ret[std.Login][fmt.Sprintf("%d", s.Challenge)] = s
						}
					}
				}
				return ret, nil
			}
		}))
	router.GET("/api/students/", apiHandler(
		func(httprouter.Params, []byte) (interface{}, error) {
			return getStudents()
		}))
	router.POST("/api/students/", remoteValidatorHandler(apiHandler(createStudent)))
	router.GET("/api/students/:sid/", apiHandler(studentHandler(
		func(std Student, _ []byte) (interface{}, error) {
			return std, nil
		})))
	router.PUT("/api/students/:sid/", remoteValidatorHandler(apiHandler(studentHandler(updateStudent))))
	router.DELETE("/api/students/:sid/", remoteValidatorHandler(apiHandler(studentHandler(
		func(std Student, _ []byte) (interface{}, error) {
			return std.Delete()
		}))))
	router.GET("/api/students/:sid/progress", apiHandler(studentHandler(
		func(std Student, _ []byte) (interface{}, error) {
			ret := map[string]UnlockedChallenge{}

			if sts, err := std.getStates(); err == nil {
				for _, s := range sts {
					ret[fmt.Sprintf("%d", s.Challenge)] = s
				}
			}

			return ret, nil
		})))
}

type Student struct {
	Id    int64      `json:"id"`
	Login string     `json:"login"`
	Time  *time.Time `json:"time"`
	IP    *string    `json:"ip"`
	MAC   *string    `json:"mac"`
}

type uploadedStudent struct {
	Login string `json:"login"`
	IP    string `json:"ip"`
	MAC   string `json:"mac"`
}

func getStudents() (students []Student, err error) {
	if rows, errr := DBQuery("SELECT S.id_student, S.login, MAX(L.time), L.ip, L.mac FROM students S INNER JOIN (SELECT a.id_student, a.time, a.ip, a.mac FROM student_login a INNER JOIN (SELECT id_student, MAX(time) AS time FROM student_login GROUP BY id_student) b ON a.id_student = b.id_student AND a.time = b.time) L ON S.id_student = L.id_student GROUP BY id_student"); errr != nil {
		return nil, errr
	} else {
		defer rows.Close()

		for rows.Next() {
			var s Student
			if err = rows.Scan(&s.Id, &s.Login, &s.Time, &s.IP, &s.MAC); err != nil {
				return
			}
			students = append(students, s)
		}
		if err = rows.Err(); err != nil {
			return
		}

		return
	}
}

func getStudent(id int) (s Student, err error) {
	err = DBQueryRow("SELECT S.id_student, S.login, MAX(L.time), L.ip, L.mac FROM students S INNER JOIN (SELECT a.id_student, a.time, a.ip, a.mac FROM student_login a INNER JOIN (SELECT id_student, MAX(time) AS time FROM student_login GROUP BY id_student) b ON a.id_student = b.id_student AND a.time = b.time) L ON S.id_student = L.id_student WHERE S.id_student=?", id).Scan(&s.Id, &s.Login, &s.Time, &s.IP, &s.MAC)
	return
}

func getStudentByLogin(login string) (s Student, err error) {
	err = DBQueryRow("SELECT S.id_student, S.login, MAX(L.time), L.ip, L.mac FROM students S INNER JOIN (SELECT a.id_student, a.time, a.ip, a.mac FROM student_login a INNER JOIN (SELECT id_student, MAX(time) AS time FROM student_login GROUP BY id_student) b ON a.id_student = b.id_student AND a.time = b.time) L ON S.id_student = L.id_student WHERE login=?", login).Scan(&s.Id, &s.Login, &s.Time, &s.IP, &s.MAC)
	return
}

func studentExists(login string) bool {
	var z int
	err := DBQueryRow("SELECT 1 FROM students WHERE login=?", login).Scan(&z)
	return err == nil && z == 1
}

func NewStudent(login string) (Student, error) {
	t := time.Now()
	if res, err := DBExec("INSERT INTO students (login, time) VALUES (?, ?)", login, t); err != nil {
		return Student{}, err
	} else if sid, err := res.LastInsertId(); err != nil {
		return Student{}, err
	} else {
		return Student{sid, login, &t, nil, nil}, nil
	}
}

func (s Student) GetPKey() []byte {
	return hmac.New(sha512.New512_224, []byte(sharedSecret)).Sum([]byte(s.Login))
}

func (s Student) Update() (int64, error) {
	if res, err := DBExec("UPDATE students SET login = ?, time = ? WHERE id_student = ?", s.Login, s.Time, s.Id); err != nil {
		return 0, err
	} else if nb, err := res.RowsAffected(); err != nil {
		return 0, err
	} else {
		return nb, err
	}
}

func (s Student) Delete() (int64, error) {
	if res, err := DBExec("DELETE FROM students WHERE id_student = ?", s.Id); err != nil {
		return 0, err
	} else if nb, err := res.RowsAffected(); err != nil {
		return 0, err
	} else {
		return nb, err
	}
}

func ClearStudents() (int64, error) {
	if res, err := DBExec("DELETE FROM students"); err != nil {
		return 0, err
	} else if nb, err := res.RowsAffected(); err != nil {
		return 0, err
	} else {
		return nb, err
	}
}

func createStudent(_ httprouter.Params, body []byte) (interface{}, error) {
	var err error
	var std uploadedStudent
	if err = json.Unmarshal(body, &std); err != nil {
		return nil, err
	}

	var exist Student
	if exist, err = getStudentByLogin(strings.TrimSpace(std.Login)); err != nil {
		if exist, err = NewStudent(strings.TrimSpace(std.Login)); err != nil {
			return nil, err
		}
	}
	exist.registerAccess(std.IP, std.MAC)

	ip := fmt.Sprintf("172.23.0.%d", exist.IPSuffix())
	exist.IP = &ip

	return exist, nil
}

func updateStudent(current Student, body []byte) (interface{}, error) {
	var new Student
	if err := json.Unmarshal(body, &new); err != nil {
		return nil, err
	}

	current.Login = new.Login
	current.Time = new.Time
	return current.Update()
}

type UnlockedChallenge struct {
	Id        int64     `json:"id"`
	IdStudent int64     `json:"id_student"`
	Challenge int       `json:"challenge"`
	Time      time.Time `json:"time"`
	Value     string    `json:"value,omitempty"`
}

func (s Student) getStates() (ucs []UnlockedChallenge, err error) {
	if rows, errr := DBQuery("SELECT id_st, challenge, time FROM student_challenges WHERE id_student = ?", s.Id); errr != nil {
		return nil, errr
	} else {
		defer rows.Close()

		for rows.Next() {
			var u UnlockedChallenge
			u.IdStudent = s.Id
			if err = rows.Scan(&u.Id, &u.Challenge, &u.Time); err != nil {
				return
			}
			ucs = append(ucs, u)
		}
		if err = rows.Err(); err != nil {
			return
		}

		return
	}
}

func (s Student) getStatesByChallenge() (ucs []UnlockedChallenge, err error) {
	if rows, errr := DBQuery("SELECT id_st, challenge, MIN(time), value FROM student_challenges WHERE id_student = ? GROUP BY challenge, id_student", s.Id); errr != nil {
		return nil, errr
	} else {
		defer rows.Close()

		for rows.Next() {
			var u UnlockedChallenge
			u.IdStudent = s.Id
			if err = rows.Scan(&u.Id, &u.Challenge, &u.Time, &u.Value); err != nil {
				return
			}
			ucs = append(ucs, u)
		}
		if err = rows.Err(); err != nil {
			return
		}

		return
	}
}

func (s Student) UnlockNewChallenge(challenge int, value string) (UnlockedChallenge, error) {
	if res, err := DBExec("INSERT INTO student_challenges (id_student, challenge, time, value) VALUES (?, ?, ?, ?)", s.Id, challenge, time.Now(), value); err != nil {
		return UnlockedChallenge{}, err
	} else if utid, err := res.LastInsertId(); err != nil {
		return UnlockedChallenge{}, err
	} else {
		return UnlockedChallenge{utid, s.Id, challenge, time.Now(), value}, err
	}
}

func (s Student) UpdateUnlockedChallenge(challenge int, value string) (UnlockedChallenge, error) {
	if _, err := DBExec("UPDATE student_challenges SET time = ?, value = ? WHERE id_student = ? AND challenge = ?", time.Now(), value, s.Id, challenge); err != nil {
		return UnlockedChallenge{}, err
	} else {
		return UnlockedChallenge{0, s.Id, challenge, time.Now(), value}, err
	}
}

func (s Student) registerAccess(ip, mac string) error {
	if res, err := DBExec("INSERT INTO student_login (id_student, ip, mac, time) VALUES (?, ?, ?, ?)", s.Id, ip, mac, time.Now()); err != nil {
		return err
	} else if _, err := res.LastInsertId(); err != nil {
		return err
	} else {
		return err
	}
}