package v1

import (
	"database/sql"

	"github.com/osuyozora/api/common"
)

type friendData struct {
	userData
	IsMutual bool `json:"is_mutual"`
}

type friendsGETResponse struct {
	common.ResponseBase
	Friends []friendData `json:"friends"`
}

// FriendsGET is the API request handler for GET /friends.
// It retrieves an user's friends, and whether the friendship is mutual or not.
func FriendsGET(md common.MethodData) common.CodeMessager {
	var myFrienders []int
	myFriendersRaw, err := md.DB.Query("SELECT user1 FROM users_relationships WHERE user2 = ?", md.ID())
	if err != nil {
		md.Err(err)
		return Err500
	}
	defer myFriendersRaw.Close()
	for myFriendersRaw.Next() {
		var i int
		err := myFriendersRaw.Scan(&i)
		if err != nil {
			md.Err(err)
			continue
		}
		myFrienders = append(myFrienders, i)
	}
	if err := myFriendersRaw.Err(); err != nil {
		md.Err(err)
	}

	myFriendsQuery := `
SELECT
	users.id, users.username, users.register_datetime, users.privileges, users.latest_activity,

	users_stats.username_aka,
	users_stats.country
FROM users_relationships
LEFT JOIN users
ON users_relationships.user2 = users.id
LEFT JOIN users_stats
ON users_relationships.user2=users_stats.id
WHERE users_relationships.user1=?
`

	myFriendsQuery += common.Sort(md, common.SortConfiguration{
		Allowed: []string{
			"id",
			"username",
			"latest_activity",
		},
		Default: "users.id asc",
		Table:   "users",
	}) + "\n"

	results, err := md.DB.Query(myFriendsQuery+common.Paginate(md.Query("p"), md.Query("l"), 100), md.ID())
	if err != nil {
		md.Err(err)
		return Err500
	}

	var myFriends []friendData

	defer results.Close()
	for results.Next() {
		newFriend := friendPuts(md, results)
		for _, uid := range myFrienders {
			if uid == newFriend.ID {
				newFriend.IsMutual = true
				break
			}
		}
		myFriends = append(myFriends, newFriend)
	}
	if err := results.Err(); err != nil {
		md.Err(err)
	}

	r := friendsGETResponse{}
	r.Code = 200
	r.Friends = myFriends
	return r
}

func friendPuts(md common.MethodData, row *sql.Rows) (user friendData) {
	var err error

	err = row.Scan(&user.ID, &user.Username, &user.RegisteredOn, &user.Privileges, &user.LatestActivity, &user.UsernameAKA, &user.Country)
	if err != nil {
		md.Err(err)
		return
	}

	return
}

type friendsWithResponse struct {
	common.ResponseBase
	Friends bool `json:"friend"`
	Mutual  bool `json:"mutual"`
}

// FriendsWithGET checks the current user is friends with the one passed in the request path.
func FriendsWithGET(md common.MethodData) common.CodeMessager {
	var r friendsWithResponse
	r.Code = 200
	uid := common.Int(md.Query("id"))
	if uid == 0 {
		return r
	}
	err := md.DB.QueryRow("SELECT EXISTS(SELECT 1 FROM users_relationships WHERE user1 = ? AND user2 = ? LIMIT 1), EXISTS(SELECT 1 FROM users_relationships WHERE user2 = ? AND user1 = ? LIMIT 1)", md.ID(), uid, md.ID(), uid).Scan(&r.Friends, &r.Mutual)
	if err != sql.ErrNoRows && err != nil {
		md.Err(err)
		return Err500
	}
	if !r.Friends {
		r.Mutual = false
	}
	return r
}

// FriendsAddPOST adds an user to the friends.
func FriendsAddPOST(md common.MethodData) common.CodeMessager {
	var u struct {
		User int `json:"user"`
	}
	md.Unmarshal(&u)
	return addFriend(md, u.User)
}

func addFriend(md common.MethodData, u int) common.CodeMessager {
	if md.ID() == u {
		return common.SimpleResponse(406, "Just so you know: you can't add yourself to your friends.")
	}
	if !userExists(md, u) {
		return common.SimpleResponse(404, "I'd also like to be friends with someone who doesn't even exist (???), however that's NOT POSSIBLE.")
	}
	var (
		relExists bool
		isMutual  bool
	)
	err := md.DB.QueryRow("SELECT EXISTS(SELECT 1 FROM users_relationships WHERE user1 = ? AND user2 = ?), EXISTS(SELECT 1 FROM users_relationships WHERE user2 = ? AND user1 = ?)", md.ID(), u, md.ID(), u).Scan(&relExists, &isMutual)
	if err != nil && err != sql.ErrNoRows {
		md.Err(err)
		return Err500
	}
	if !relExists {
		_, err := md.DB.Exec("INSERT INTO users_relationships(user1, user2) VALUES (?, ?)", md.User.UserID, u)
		if err != nil {
			md.Err(err)
			return Err500
		}
	}
	var r friendsWithResponse
	r.Code = 200
	r.Friends = true
	r.Mutual = isMutual
	return r
}

// userExists makes sure an user exists.
func userExists(md common.MethodData, u int) (r bool) {
	err := md.DB.QueryRow("SELECT EXISTS(SELECT 1 FROM users WHERE id = ? AND "+
		md.User.OnlyUserPublic(true)+")", u).Scan(&r)
	if err != nil && err != sql.ErrNoRows {
		md.Err(err)
	}
	return
}

// FriendsDelPOST deletes an user's friend.
func FriendsDelPOST(md common.MethodData) common.CodeMessager {
	var u struct {
		User int `json:"user"`
	}
	md.Unmarshal(&u)
	return delFriend(md, u.User)
}

func delFriend(md common.MethodData, u int) common.CodeMessager {
	_, err := md.DB.Exec("DELETE FROM users_relationships WHERE user1 = ? AND user2 = ?", md.ID(), u)
	if err != nil {
		md.Err(err)
		return Err500
	}
	r := friendsWithResponse{
		Friends: false,
		Mutual:  false,
	}
	r.Code = 200
	return r
}