package api

import (
	"fmt"
	"github.com/gin-gonic/gin"
	db "main.go/database"
	"main.go/tools"
	. "main.go/type"
	"math"
)

// hasAlreadySolved 检查某道题是否已经被某用户解出。
func hasAlreadySolved(uid int, cid int) (exists bool) {
	Link()
	DB := db.DBsnctf
	err := DB.Raw("SELECT EXISTS(SELECT 1 FROM solve WHERE uid=? AND cid=?)", uid, cid).Scan(&exists).Error
	if err != nil {
		return false
	}
	return exists
}

// isChallengeExisted 检查数据库中是否存在某个题目。
func isChallengeExisted(id int) (exists bool) {
	Link()
	DB := db.DBsnctf
	command := "SELECT EXISTS(SELECT 1 FROM challenge WHERE id = ?);"
	err := DB.Raw(command, id).Scan(&exists).Error
	if err != nil {
		return false
	}
	return exists
}

//addSubmission 添加一个提交记录。
func addSubmission(s *Submission) error {
	Link()
	DB := db.DBsnctf
	err := DB.Table("submission").Create(&s).Error
	if err != nil {
		return err
	}

	return nil

}

// getFlag 根据题目id获取该题的flag
func getFlag(id int) (flag string, err error) {
	Link()
	DB := db.DBsnctf
	err = DB.Table("challenge").Select("flag").Where("id = ?", id).Find(&flag).Error
	if err != nil {
		return "", err
	}
	return flag, nil
}

// addSolve 操作数据库加入一条正确的flag提交记录。
func addSolve(s *Solve) error {
	DB := db.DBsnctf
	err := DB.Table("solve").Create(&s).Error
	if err != nil {
		return err
	}
	return nil
}

// addUserScore 操作数据库为指定用户增加某题的分数。
func addUserScore(username string, cid int) error {
	var newScore int
	DB := db.DBsnctf
	err := DB.Table("challenge").Select("score").Where("id = ?", cid).Find(&newScore).Error
	if err != nil {
		return err
	}

	command := "UPDATE score SET score=score+? WHERE username=?"
	err = DB.Exec(command, newScore, username).Error
	if err != nil {
		return err
	}
	return nil
}

// updateUserScores 操作数据库更新解出用户的分数。
func updateUserScores(reducedScore, cid int) error {

	DB := db.DBsnctf
	command := "UPDATE score SET score=score-? WHERE EXISTS(SELECT 1 FROM user,solve WHERE user.id=solve.uid AND score.username=user.username AND solve.cid=?);"
	err := DB.Exec(command, reducedScore, cid).Error

	return err
}

// editChallengeScore 操作数据库修改指定题目增的动态分数。
func editChallengeScore(cid int) (reducedScore int, err error) {
	DB := db.DBsnctf
	var currentScore int
	err = DB.Table("challenge").Select("score").Where("id = ?", cid).Find(&currentScore).Error
	command := "SELECT score FROM challenge WHERE id=? LIMIT 1;"
	if err != nil {
		return 0, err
	}

	solverCount, err := getSolverCount(cid)
	if err != nil {
		return 0, err
	}
	// According to https://github.com/o-o-overflow/scoring-playground
	newScore := int(100 + (1000-100)/(1.0+float64(solverCount)*0.04*math.Log(float64(solverCount))))
	reducedScore = currentScore - newScore

	command = "UPDATE challenge SET score=? WHERE id=?;"
	err = DB.Exec(command, newScore, cid).Error
	if err != nil {
		return 0, err
	}

	return reducedScore, nil
}

// SubmitFlag 提交flag
func SubmitFlag(c *gin.Context) {
	var request SubmissionRequest
	if err := c.ShouldBindJSON(&request); err != nil {

		c.JSON(400, gin.H{"code": 400, "msg": "Request format wrong!"})
		return
	}

	session, err := Store.Get(c.Request, "SNCTFSESSID")
	if err != nil {
		c.JSON(400, gin.H{"code": 400, "msg": "GET SNCTFSESSID error!"})
		return
	}
	user, ok := session.Values["user"].(User)
	if !ok {
		c.JSON(400, gin.H{"code": 400, "msg": "GET user error!"})
		return
	}
	// 检查题目是否存在
	if !isChallengeExisted(request.Cid) {
		c.JSON(400, gin.H{"code": 400, "msg": "Challenge not existed!"})
		return
	}
	// Submission记录
	solvedTime := tools.Timestamp()
	submission := &Submission{
		UserID:      user.ID,
		ChallengeID: request.Cid,
		Flag:        request.Flag,
		IP:          c.ClientIP(),
		Time:        solvedTime,
	}
	err = addSubmission(submission)
	if err != nil {
		c.JSON(400, gin.H{"code": 400, "msg": "Record submission failure!"})
		return
	}
	// 是否已经解出该题
	if hasAlreadySolved(user.ID, request.Cid) {
		c.JSON(200, gin.H{"code": 400, "msg": "Already solved!"})
		return
	}
	// 获取flag
	flag, err := getFlag(request.Cid)
	if err != nil {
		fmt.Println(err)
		c.JSON(200, gin.H{"code": 400, "msg": "Get flag failure!"})
		return
	}
	// 检查flag是否正确
	if flag != request.Flag {
		c.JSON(200, gin.H{"code": 400, "msg": "Wrong flag!"})
		return
	} else {
		// Solve记录
		solve := &Solve{
			UserID:      user.ID,
			ChallengeID: request.Cid,
			Time:        solvedTime,
		}
		err = addSolve(solve)
		if err != nil {
			c.JSON(200, gin.H{"code": 400, "msg": "Record solve failure!"})
			return
		}
		//加分
		err = addUserScore(user.Username, request.Cid)
		if err != nil {
			c.JSON(400, gin.H{"code": 400, "msg": "Add score failure!"})
			return
		}
		// 题目动态分数

		reducedScore, err := editChallengeScore(request.Cid)
		if err != nil {
			c.JSON(400, gin.H{"code": 400, "msg": "Edit challenge score failure!"})
			return
		}
		//更新所有用户分数
		err = updateUserScores(reducedScore, request.Cid)
		if err != nil {
			c.JSON(400, gin.H{"code": 400, "msg": "Update user scores failure!"})
			return
		}
		c.JSON(200, gin.H{"code": 200, "msg": "Correct flag!"})
		return

	}

}