package main

import (
	"crypto/hmac"
	"crypto/sha512"
	"encoding/json"
	"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][]UnlockedChallenge{}
				for _, std := range stds {
					if ret[std.Login], err = std.getStates(); err != nil {
						return nil, err
					}
				}
				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()
		}))))
}

type Student struct {
	Id    int64     `json:"id"`
	Login string    `json:"login"`
	Time  time.Time `json:"time"`
}

func getStudents() (students []Student, err error) {
	if rows, errr := DBQuery("SELECT id_student, login, time FROM students"); 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); 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 id_student, login, time FROM students WHERE id_student=?", id).Scan(&s.Id, &s.Login, &s.Time)
	return
}

func getStudentByLogin(login string) (s Student, err error) {
	err = DBQueryRow("SELECT id_student, login, time FROM students WHERE login=?", login).Scan(&s.Id, &s.Login, &s.Time)
	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) {
	if res, err := DBExec("INSERT INTO students (login, time) VALUES (?, ?)", login, time.Now()); err != nil {
		return Student{}, err
	} else if sid, err := res.LastInsertId(); err != nil {
		return Student{}, err
	} else {
		return Student{sid, login, time.Now()}, 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 std Student
	if err := json.Unmarshal(body, &std); err != nil {
		return nil, err
	}

	if exist, err := getStudentByLogin(strings.TrimSpace(std.Login)); err != nil {
		return NewStudent(strings.TrimSpace(std.Login))
	} else {
		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"`
}

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) 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()}, err
	}
}