package user

import (
	"context"
	"database/sql"
	"fmt"
	"sort"
	"strings"
	"time"

	"github.com/owncast/owncast/config"
	"github.com/owncast/owncast/core/data"
	"github.com/owncast/owncast/db"
	"github.com/owncast/owncast/utils"
	"github.com/pkg/errors"
	"github.com/teris-io/shortid"

	log "github.com/sirupsen/logrus"
)

var _datastore *data.Datastore

const (
	moderatorScopeKey              = "MODERATOR"
	minSuggestedUsernamePoolLength = 10
)

// User represents a single chat user.
type User struct {
	ID              string     `json:"id"`
	DisplayName     string     `json:"displayName"`
	DisplayColor    int        `json:"displayColor"`
	CreatedAt       time.Time  `json:"createdAt"`
	DisabledAt      *time.Time `json:"disabledAt,omitempty"`
	PreviousNames   []string   `json:"previousNames"`
	NameChangedAt   *time.Time `json:"nameChangedAt,omitempty"`
	Scopes          []string   `json:"scopes,omitempty"`
	IsBot           bool       `json:"isBot"`
	AuthenticatedAt *time.Time `json:"-"`
	Authenticated   bool       `json:"authenticated"`
}

// IsEnabled will return if this single user is enabled.
func (u *User) IsEnabled() bool {
	return u.DisabledAt == nil
}

// IsModerator will return if the user has moderation privileges.
func (u *User) IsModerator() bool {
	_, hasModerationScope := utils.FindInSlice(u.Scopes, moderatorScopeKey)
	return hasModerationScope
}

// SetupUsers will perform the initial initialization of the user package.
func SetupUsers() {
	_datastore = data.GetDatastore()
}

func generateDisplayName() string {
	suggestedUsernamesList := data.GetSuggestedUsernamesList()

	if len(suggestedUsernamesList) >= minSuggestedUsernamePoolLength {
		index := utils.RandomIndex(len(suggestedUsernamesList))
		return suggestedUsernamesList[index]
	} else {
		return utils.GeneratePhrase()
	}
}

// CreateAnonymousUser will create a new anonymous user with the provided display name.
func CreateAnonymousUser(displayName string) (*User, string, error) {
	// Try to assign a name that was requested.
	if displayName != "" {
		// If name isn't available then generate a random one.
		if available, _ := IsDisplayNameAvailable(displayName); !available {
			displayName = generateDisplayName()
		}
	} else {
		displayName = generateDisplayName()
	}

	displayColor := utils.GenerateRandomDisplayColor(config.MaxUserColor)

	id := shortid.MustGenerate()
	user := &User{
		ID:           id,
		DisplayName:  displayName,
		DisplayColor: displayColor,
		CreatedAt:    time.Now(),
	}

	// Create new user.
	if err := create(user); err != nil {
		return nil, "", err
	}

	// Assign it an access token.
	accessToken, err := utils.GenerateAccessToken()
	if err != nil {
		log.Errorln("Unable to create access token for new user")
		return nil, "", err
	}
	if err := addAccessTokenForUser(accessToken, id); err != nil {
		return nil, "", errors.Wrap(err, "unable to save access token for new user")
	}

	return user, accessToken, nil
}

// IsDisplayNameAvailable will check if the proposed name is available for use.
func IsDisplayNameAvailable(displayName string) (bool, error) {
	if available, err := _datastore.GetQueries().IsDisplayNameAvailable(context.Background(), displayName); err != nil {
		return false, errors.Wrap(err, "unable to check if display name is available")
	} else if available != 0 {
		return false, nil
	}

	return true, nil
}

// ChangeUsername will change the user associated to userID from one display name to another.
func ChangeUsername(userID string, username string) error {
	_datastore.DbLock.Lock()
	defer _datastore.DbLock.Unlock()

	if err := _datastore.GetQueries().ChangeDisplayName(context.Background(), db.ChangeDisplayNameParams{
		DisplayName:   username,
		ID:            userID,
		PreviousNames: sql.NullString{String: fmt.Sprintf(",%s", username), Valid: true},
		NamechangedAt: sql.NullTime{Time: time.Now(), Valid: true},
	}); err != nil {
		return errors.Wrap(err, "unable to change display name")
	}

	return nil
}

// ChangeUserColor will change the user associated to userID from one display name to another.
func ChangeUserColor(userID string, color int) error {
	_datastore.DbLock.Lock()
	defer _datastore.DbLock.Unlock()

	if err := _datastore.GetQueries().ChangeDisplayColor(context.Background(), db.ChangeDisplayColorParams{
		DisplayColor: int32(color),
		ID:           userID,
	}); err != nil {
		return errors.Wrap(err, "unable to change display color")
	}

	return nil
}

func addAccessTokenForUser(accessToken, userID string) error {
	return _datastore.GetQueries().AddAccessTokenForUser(context.Background(), db.AddAccessTokenForUserParams{
		Token:  accessToken,
		UserID: userID,
	})
}

func create(user *User) error {
	_datastore.DbLock.Lock()
	defer _datastore.DbLock.Unlock()

	tx, err := _datastore.DB.Begin()
	if err != nil {
		log.Debugln(err)
	}
	defer func() {
		_ = tx.Rollback()
	}()

	stmt, err := tx.Prepare("INSERT INTO users(id, display_name, display_color, previous_names, created_at) values(?, ?, ?, ?, ?)")
	if err != nil {
		log.Debugln(err)
	}
	defer stmt.Close()

	_, err = stmt.Exec(user.ID, user.DisplayName, user.DisplayColor, user.DisplayName, user.CreatedAt)
	if err != nil {
		log.Errorln("error creating new user", err)
		return err
	}

	return tx.Commit()
}

// SetEnabled will set the enabled status of a single user by ID.
func SetEnabled(userID string, enabled bool) error {
	_datastore.DbLock.Lock()
	defer _datastore.DbLock.Unlock()

	tx, err := _datastore.DB.Begin()
	if err != nil {
		return err
	}

	defer tx.Rollback() //nolint

	var stmt *sql.Stmt
	if !enabled {
		stmt, err = tx.Prepare("UPDATE users SET disabled_at=DATETIME('now', 'localtime') WHERE id IS ?")
	} else {
		stmt, err = tx.Prepare("UPDATE users SET disabled_at=null WHERE id IS ?")
	}

	if err != nil {
		return err
	}

	defer stmt.Close()

	if _, err := stmt.Exec(userID); err != nil {
		return err
	}

	return tx.Commit()
}

// GetUserByToken will return a user by an access token.
func GetUserByToken(token string) *User {
	u, err := _datastore.GetQueries().GetUserByAccessToken(context.Background(), token)
	if err != nil {
		return nil
	}

	var scopes []string
	if u.Scopes.Valid {
		scopes = strings.Split(u.Scopes.String, ",")
	}

	var disabledAt *time.Time
	if u.DisabledAt.Valid {
		disabledAt = &u.DisabledAt.Time
	}

	var authenticatedAt *time.Time
	if u.AuthenticatedAt.Valid {
		authenticatedAt = &u.AuthenticatedAt.Time
	}

	return &User{
		ID:              u.ID,
		DisplayName:     u.DisplayName,
		DisplayColor:    int(u.DisplayColor),
		CreatedAt:       u.CreatedAt.Time,
		DisabledAt:      disabledAt,
		PreviousNames:   strings.Split(u.PreviousNames.String, ","),
		NameChangedAt:   &u.NamechangedAt.Time,
		AuthenticatedAt: authenticatedAt,
		Authenticated:   authenticatedAt != nil,
		Scopes:          scopes,
	}
}

// SetAccessTokenToOwner will reassign an access token to be owned by a
// different user. Used for logging in with external auth.
func SetAccessTokenToOwner(token, userID string) error {
	return _datastore.GetQueries().SetAccessTokenToOwner(context.Background(), db.SetAccessTokenToOwnerParams{
		UserID: userID,
		Token:  token,
	})
}

// SetUserAsAuthenticated will mark that a user has been authenticated
// in some way.
func SetUserAsAuthenticated(userID string) error {
	return errors.Wrap(_datastore.GetQueries().SetUserAsAuthenticated(context.Background(), userID), "unable to set user as authenticated")
}

// SetModerator will add or remove moderator status for a single user by ID.
func SetModerator(userID string, isModerator bool) error {
	if isModerator {
		return addScopeToUser(userID, moderatorScopeKey)
	}

	return removeScopeFromUser(userID, moderatorScopeKey)
}

func addScopeToUser(userID string, scope string) error {
	u := GetUserByID(userID)
	if u == nil {
		return errors.New("user not found when modifying scope")
	}

	scopesString := u.Scopes
	scopes := utils.StringSliceToMap(scopesString)
	scopes[scope] = true

	scopesSlice := utils.StringMapKeys(scopes)

	return setScopesOnUser(userID, scopesSlice)
}

func removeScopeFromUser(userID string, scope string) error {
	u := GetUserByID(userID)
	scopesString := u.Scopes
	scopes := utils.StringSliceToMap(scopesString)
	delete(scopes, scope)

	scopesSlice := utils.StringMapKeys(scopes)

	return setScopesOnUser(userID, scopesSlice)
}

func setScopesOnUser(userID string, scopes []string) error {
	_datastore.DbLock.Lock()
	defer _datastore.DbLock.Unlock()

	tx, err := _datastore.DB.Begin()
	if err != nil {
		return err
	}

	defer tx.Rollback() //nolint

	scopesSliceString := strings.TrimSpace(strings.Join(scopes, ","))
	stmt, err := tx.Prepare("UPDATE users SET scopes=? WHERE id IS ?")
	if err != nil {
		return err
	}

	defer stmt.Close()

	var val *string
	if scopesSliceString == "" {
		val = nil
	} else {
		val = &scopesSliceString
	}

	if _, err := stmt.Exec(val, userID); err != nil {
		return err
	}

	return tx.Commit()
}

// GetUserByID will return a user by a user ID.
func GetUserByID(id string) *User {
	_datastore.DbLock.Lock()
	defer _datastore.DbLock.Unlock()

	query := "SELECT id, display_name, display_color, created_at, disabled_at, previous_names, namechanged_at, scopes FROM users WHERE id = ?"
	row := _datastore.DB.QueryRow(query, id)
	if row == nil {
		log.Errorln(row)
		return nil
	}
	return getUserFromRow(row)
}

// GetDisabledUsers will return back all the currently disabled users that are not API users.
func GetDisabledUsers() []*User {
	query := "SELECT id, display_name, scopes, display_color, created_at, disabled_at, previous_names, namechanged_at FROM users WHERE disabled_at IS NOT NULL AND type IS NOT 'API'"

	rows, err := _datastore.DB.Query(query)
	if err != nil {
		log.Errorln(err)
		return nil
	}
	defer rows.Close()

	users := getUsersFromRows(rows)

	sort.Slice(users, func(i, j int) bool {
		return users[i].DisabledAt.Before(*users[j].DisabledAt)
	})

	return users
}

// GetModeratorUsers will return a list of users with moderator access.
func GetModeratorUsers() []*User {
	query := `SELECT id, display_name, scopes, display_color, created_at, disabled_at, previous_names, namechanged_at FROM (
		WITH RECURSIVE split(id, display_name, scopes, display_color, created_at, disabled_at, previous_names, namechanged_at, scope, rest) AS (
		  SELECT id, display_name, scopes, display_color, created_at, disabled_at, previous_names, namechanged_at, '', scopes || ',' FROM users
		   UNION ALL
		  SELECT id, display_name, scopes, display_color, created_at, disabled_at, previous_names, namechanged_at,
				 substr(rest, 0, instr(rest, ',')),
				 substr(rest, instr(rest, ',')+1)
			FROM split
		   WHERE rest <> '')
		SELECT id, display_name, scopes, display_color, created_at, disabled_at, previous_names, namechanged_at, scope
		  FROM split
		 WHERE scope <> ''
		 ORDER BY created_at
	  ) AS token WHERE token.scope = ?`

	rows, err := _datastore.DB.Query(query, moderatorScopeKey)
	if err != nil {
		log.Errorln(err)
		return nil
	}
	defer rows.Close()

	users := getUsersFromRows(rows)

	return users
}

func getUsersFromRows(rows *sql.Rows) []*User {
	users := make([]*User, 0)

	for rows.Next() {
		var id string
		var displayName string
		var displayColor int
		var createdAt time.Time
		var disabledAt *time.Time
		var previousUsernames string
		var userNameChangedAt *time.Time
		var scopesString *string

		if err := rows.Scan(&id, &displayName, &scopesString, &displayColor, &createdAt, &disabledAt, &previousUsernames, &userNameChangedAt); err != nil {
			log.Errorln("error creating collection of users from results", err)
			return nil
		}

		var scopes []string
		if scopesString != nil {
			scopes = strings.Split(*scopesString, ",")
		}

		user := &User{
			ID:            id,
			DisplayName:   displayName,
			DisplayColor:  displayColor,
			CreatedAt:     createdAt,
			DisabledAt:    disabledAt,
			PreviousNames: strings.Split(previousUsernames, ","),
			NameChangedAt: userNameChangedAt,
			Scopes:        scopes,
		}
		users = append(users, user)
	}

	sort.Slice(users, func(i, j int) bool {
		return users[i].CreatedAt.Before(users[j].CreatedAt)
	})

	return users
}

func getUserFromRow(row *sql.Row) *User {
	var id string
	var displayName string
	var displayColor int
	var createdAt time.Time
	var disabledAt *time.Time
	var previousUsernames string
	var userNameChangedAt *time.Time
	var scopesString *string

	if err := row.Scan(&id, &displayName, &displayColor, &createdAt, &disabledAt, &previousUsernames, &userNameChangedAt, &scopesString); err != nil {
		return nil
	}

	var scopes []string
	if scopesString != nil {
		scopes = strings.Split(*scopesString, ",")
	}

	return &User{
		ID:            id,
		DisplayName:   displayName,
		DisplayColor:  displayColor,
		CreatedAt:     createdAt,
		DisabledAt:    disabledAt,
		PreviousNames: strings.Split(previousUsernames, ","),
		NameChangedAt: userNameChangedAt,
		Scopes:        scopes,
	}
}