package main

import (
	"fmt"
	"log"
	"math"
	"net/http"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/gin-gonic/gin"
)

var (
	_score_cache         = map[int64]map[int64]*float64{}
	_score_cache_mutex   = sync.RWMutex{}
	_surveys_cache       = map[int64]*Survey{}
	_surveys_cache_mutex = sync.RWMutex{}
)

func declareAPISurveysRoutes(router *gin.RouterGroup) {
	router.GET("/surveys", func(c *gin.Context) {
		u := c.MustGet("LoggedUser").(*User)

		var response []*Survey
		var err error
		if u == nil {
			response, err = getSurveys(fmt.Sprintf("WHERE shown = TRUE AND NOW() > start_availability AND promo = %d ORDER BY start_availability ASC", currentPromo))
		} else if u.IsAdmin {
			response, err = getSurveys("ORDER BY promo DESC, start_availability ASC")
		} else {
			var surveys []*Survey
			surveys, err = getSurveys(fmt.Sprintf("WHERE shown = TRUE AND promo = %d ORDER BY start_availability ASC", u.Promo))
			if err == nil {
				for _, s := range surveys {
					if s.Group == "" || strings.Contains(u.Groups, ","+s.Group+",") {
						s.Group = ""
						response = append(response, s)
					}
				}
			}
		}

		if err != nil {
			c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"errmsg": "Impossible de lister les questionnaires. Veuillez réessayer dans quelques instants"})
			log.Printf("Unable to list surveys: %s", err.Error())
		} else {
			c.JSON(http.StatusOK, response)
		}
	})

	surveysRoutes := router.Group("/surveys/:sid")
	surveysRoutes.Use(surveyHandler)
	surveysRoutes.Use(surveyUserAccessHandler)

	surveysRoutes.GET("", func(c *gin.Context) {
		u := c.MustGet("LoggedUser").(*User)

		if u == nil {
			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"errmsg": "Veuillez vous connecter pour accéder à cette page."})
			return
		}

		c.JSON(http.StatusOK, c.MustGet("survey").(*Survey))
	})
}

func declareAPIAuthSurveysRoutes(router *gin.RouterGroup) {
	surveysRoutes := router.Group("/surveys/:sid")
	surveysRoutes.Use(surveyHandler)
	surveysRoutes.Use(surveyUserAccessHandler)

	surveysRoutes.GET("/score", func(c *gin.Context) {
		var u *User
		if user, ok := c.Get("user"); ok {
			u = user.(*User)
		} else {
			u = c.MustGet("LoggedUser").(*User)
		}
		s := c.MustGet("survey").(*Survey)

		if u.IsAdmin {
			questions, err := s.GetQuestions()
			if err != nil {
				log.Println("Unable to getQuestions:", err)
				c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"errmsg": "Unable to retrieve questions. Please try again later."})
				return
			}

			itemCount := 0
			itemCorrected := 0
			for _, q := range questions {
				res, err := q.GetResponses()
				if err != nil {
					log.Printf("Unable to GetResponses(qid=%d): %s", q.Id, err.Error())
					c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"errmsg": "An error occurs during responses retrieval."})
					return
				}

				for _, r := range res {
					itemCount += 1
					if r.TimeScored != nil && (r.TimeReported == nil || r.TimeScored.After(*r.TimeReported)) {
						itemCorrected += 1
					}
				}
			}

			c.JSON(http.StatusOK, map[string]int{"count": itemCount, "corrected": itemCorrected})
		} else if s.Promo == u.Promo && s.Shown {
			score, err := s.GetScore(u)
			if err != nil {
				log.Printf("Unable to GetScore(uid=%d;sid=%d): %s", u.Id, s.Id, err.Error())
				c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"errmsg": "An error occurs when trying to retrieve score."})
				return
			}

			if score == nil {
				c.JSON(http.StatusOK, map[string]string{"score": "N/A"})
			} else {
				c.JSON(http.StatusOK, map[string]float64{"score": math.Round(*score*10) / 10})
			}
		} else {
			c.AbortWithStatusJSON(http.StatusForbidden, gin.H{"errmsg": "Not accessible"})
			return
		}
	})

	declareAPIAuthAsksRoutes(surveysRoutes)
	declareAPIAuthDirectRoutes(surveysRoutes)
	declareAPIAuthGradesRoutes(surveysRoutes)
	declareAPIAuthQuestionsRoutes(surveysRoutes)
	declareAPIAuthResponsesRoutes(surveysRoutes)
}

func declareAPIAdminSurveysRoutes(router *gin.RouterGroup) {
	router.POST("/surveys", func(c *gin.Context) {
		var new Survey
		if err := c.ShouldBindJSON(&new); err != nil {
			c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"errmsg": err.Error()})
			return
		}

		if new.Promo == 0 {
			new.Promo = currentPromo
		}

		if s, err := NewSurvey(new.IdCategory, new.Title, new.Promo, new.Group, new.Shown, new.Direct, new.StartAvailability, new.EndAvailability); err != nil {
			log.Println("Unable to NewSurvey:", err)
			c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"errmsg": fmt.Sprintf("An error occurs during survey creation: %s", err.Error())})
			return
		} else {
			c.JSON(http.StatusOK, s)
		}
	})

	surveysRoutes := router.Group("/surveys/:sid")
	surveysRoutes.Use(surveyHandler)

	surveysRoutes.PUT("", func(c *gin.Context) {
		current := c.MustGet("survey").(*Survey)

		var new Survey
		if err := c.ShouldBindJSON(&new); err != nil {
			c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"errmsg": err.Error()})
			return
		}

		new.Id = current.Id

		if new.Direct != current.Direct {
			if new.Direct == nil {
				current.WSCloseAll("")
			} else if *new.Direct == 0 {
				current.WSWriteAll(WSMessage{
					Action: "pause",
				})
			} else {
				current.WSWriteAll(WSMessage{
					Action:     "new_question",
					QuestionId: new.Direct,
				})
			}
		}

		if survey, err := new.Update(); err != nil {
			log.Println("Unable to Update survey:", err)
			c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"errmsg": fmt.Sprintf("An error occurs during survey updation: %s", err.Error())})
			return
		} else {
			c.JSON(http.StatusOK, survey)
		}
	})
	surveysRoutes.DELETE("", func(c *gin.Context) {
		survey := c.MustGet("survey").(*Survey)

		if _, err := survey.Delete(); err != nil {
			log.Println("Unable to Delete survey:", err)
			c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"errmsg": fmt.Sprintf("An error occurs during survey deletion: %s", err.Error())})
			return
		} else {
			c.JSON(http.StatusOK, nil)
		}
	})

	surveysRoutes.GET("shares", func(c *gin.Context) {
		survey := c.MustGet("survey").(*Survey)

		if sh, err := survey.getShares(); err != nil {
			log.Println("Unable to getShares survey:", err)
			c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"errmsg": fmt.Sprintf("An error occurs during survey shares listing: %s", err.Error())})
			return
		} else {
			c.JSON(http.StatusOK, sh)
		}
	})
	surveysRoutes.POST("shares", func(c *gin.Context) {
		survey := c.MustGet("survey").(*Survey)

		if sh, err := survey.Share(); err != nil {
			log.Println("Unable to Share survey:", err)
			c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"errmsg": fmt.Sprintf("An error occurs during survey sharing: %s", err.Error())})
			return
		} else if url, err := sh.GetURL(); err != nil {
			log.Println("Unable to GetURL share:", err)
			c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"errmsg": fmt.Sprintf("An error occurs during survey sharing: %s", err.Error())})
			return
		} else {
			c.JSON(http.StatusOK, url.String())
		}
	})

	declareAPIAdminAsksRoutes(surveysRoutes)
	declareAPIAdminDirectRoutes(surveysRoutes)
	declareAPIAdminQuestionsRoutes(surveysRoutes)
}

func surveyHandler(c *gin.Context) {
	if sid, err := strconv.Atoi(string(c.Param("sid"))); err != nil {
		c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"errmsg": "Bad survey identifier."})
		return
	} else if survey, err := getSurvey(sid); err != nil {
		c.AbortWithStatusJSON(http.StatusNotFound, gin.H{"errmsg": "Survey not found."})
		return
	} else {
		c.Set("survey", survey)
		c.Next()
	}
}

func (s *Survey) checkUserAccessToSurvey(u *User) bool {
	return u.IsAdmin || (u.Promo == s.Promo && s.Shown && (s.Group == "" || strings.Contains(u.Groups, ","+s.Group+",")))
}

func surveyUserAccessHandler(c *gin.Context) {
	u := c.MustGet("LoggedUser").(*User)
	s := c.MustGet("survey").(*Survey)

	if !s.checkUserAccessToSurvey(u) {
		c.AbortWithStatusJSON(http.StatusNotFound, gin.H{"errmsg": "Survey not found."})
		return
	}

	c.Next()
}

type Survey struct {
	Id                int64     `json:"id"`
	IdCategory        int64     `json:"id_category"`
	Title             string    `json:"title"`
	Promo             uint      `json:"promo"`
	Group             string    `json:"group"`
	Shown             bool      `json:"shown"`
	Direct            *int64    `json:"direct"`
	Corrected         bool      `json:"corrected"`
	StartAvailability time.Time `json:"start_availability"`
	EndAvailability   time.Time `json:"end_availability"`
}

func getSurveys(cnd string, param ...interface{}) (surveys []*Survey, err error) {
	if rows, errr := DBQuery("SELECT id_survey, id_category, title, promo, grp, shown, direct, corrected, start_availability, end_availability FROM surveys "+cnd, param...); errr != nil {
		return nil, errr
	} else {
		defer rows.Close()

		for rows.Next() {
			var s Survey
			if err = rows.Scan(&s.Id, &s.IdCategory, &s.Title, &s.Promo, &s.Group, &s.Shown, &s.Direct, &s.Corrected, &s.StartAvailability, &s.EndAvailability); err != nil {
				return
			}
			surveys = append(surveys, &s)
		}
		if err = rows.Err(); err != nil {
			return
		}

		return
	}
}

func getSurvey(id int) (s *Survey, err error) {
	_surveys_cache_mutex.RLock()
	survey, ok := _surveys_cache[int64(id)]
	_surveys_cache_mutex.RUnlock()
	if ok {
		return survey, nil
	}

	s = new(Survey)
	err = DBQueryRow("SELECT id_survey, id_category, title, promo, grp, shown, direct, corrected, start_availability, end_availability FROM surveys WHERE id_survey=?", id).Scan(&s.Id, &s.IdCategory, &s.Title, &s.Promo, &s.Group, &s.Shown, &s.Direct, &s.Corrected, &s.StartAvailability, &s.EndAvailability)

	_surveys_cache_mutex.Lock()
	_surveys_cache[int64(id)] = s
	_surveys_cache_mutex.Unlock()
	return
}

func NewSurvey(id_category int64, title string, promo uint, group string, shown bool, direct *int64, startAvailability time.Time, endAvailability time.Time) (*Survey, error) {
	if res, err := DBExec("INSERT INTO surveys (id_category, title, promo, grp, shown, direct, start_availability, end_availability) VALUES (?, ?, ?, ?, ?, ?, ?, ?)", id_category, title, promo, group, shown, direct, startAvailability, endAvailability); err != nil {
		return nil, err
	} else if sid, err := res.LastInsertId(); err != nil {
		return nil, err
	} else {
		return &Survey{sid, id_category, title, promo, group, shown, direct, false, startAvailability, endAvailability}, nil
	}
}

func (s Survey) GetScore(u *User) (score *float64, err error) {
	_score_cache_mutex.RLock()
	if _, ok := _score_cache[u.Id]; !ok {
		_score_cache_mutex.RUnlock()
		_score_cache_mutex.Lock()
		_score_cache[u.Id] = map[int64]*float64{}
		_score_cache_mutex.Unlock()
		_score_cache_mutex.RLock()
	}

	v, ok := _score_cache[u.Id][s.Id]
	_score_cache_mutex.RUnlock()

	if ok {
		score = v
	} else {
		err = DBQueryRow("SELECT SUM(score)/COUNT(*) FROM student_scores WHERE kind = 'survey' AND id=? AND id_user=?", s.Id, u.Id).Scan(&score)
		if score != nil {
			*score = *score / 5.0
		}

		_score_cache_mutex.Lock()
		_score_cache[u.Id][s.Id] = score
		_score_cache_mutex.Unlock()
	}
	return
}

func (s Survey) GetScores() (scores map[int64]*float64, err error) {
	if rows, errr := DBQuery("SELECT id_user, SUM(score)/COUNT(*) FROM student_scores WHERE kind = 'survey' AND id_survey=? GROUP BY id_user", s.Id); errr != nil {
		return nil, errr
	} else {
		defer rows.Close()

		scores = map[int64]*float64{}

		for rows.Next() {
			var id_user int64
			var score *float64

			if err = rows.Scan(&id_user, &score); err != nil {
				return
			}
			scores[id_user] = score
		}
		if err = rows.Err(); err != nil {
			return
		}
	}

	return
}

func (s *Survey) Update() (*Survey, error) {
	if _, err := DBExec("UPDATE surveys SET id_category = ?, title = ?, promo = ?, grp = ?, shown = ?, direct = ?, corrected = ?, start_availability = ?, end_availability = ? WHERE id_survey = ?", s.IdCategory, s.Title, s.Promo, s.Group, s.Shown, s.Direct, s.Corrected, s.StartAvailability, s.EndAvailability, s.Id); err != nil {
		return nil, err
	} else {
		_surveys_cache_mutex.Lock()
		_surveys_cache[s.Id] = s
		_surveys_cache_mutex.Unlock()
		return s, err
	}
}

func (s Survey) Delete() (int64, error) {
	DBExec("DELETE FROM survey_shared WHERE id_survey = ?", s.Id)
	if res, err := DBExec("DELETE FROM surveys WHERE id_survey = ?", s.Id); err != nil {
		return 0, err
	} else if nb, err := res.RowsAffected(); err != nil {
		return 0, err
	} else {
		_surveys_cache_mutex.Lock()
		delete(_surveys_cache, s.Id)
		_surveys_cache_mutex.Unlock()
		return nb, err
	}
}

func ClearSurveys() (int64, error) {
	if res, err := DBExec("DELETE FROM surveys"); err != nil {
		return 0, err
	} else if nb, err := res.RowsAffected(); err != nil {
		return 0, err
	} else {
		_surveys_cache_mutex.Lock()
		_surveys_cache = map[int64]*Survey{}
		_surveys_cache_mutex.Unlock()
		return nb, err
	}
}