package database

import (
	"database/sql"
	"errors"
	"time"

	"git.noroutes.net/NoRoutes/vibetunes/internal/idgen"
)

type User struct {
	ID           string
	Username     string
	Email        string
	PasswordHash sql.NullString
	IsAdmin      bool
	Disabled     bool
	ExternalAuth bool
	CreatedAt    time.Time
	LastLoginAt  sql.NullTime
}

var ErrNotFound = errors.New("not found")

func CountUsers(db *sql.DB) (int, error) {
	var n int
	err := db.QueryRow(`SELECT COUNT(*) FROM users`).Scan(&n)
	return n, err
}

// CreateUser inserts a new user. passwordHash may be empty for
// external-auth-only accounts.
func CreateUser(db *sql.DB, username, email, passwordHash string, isAdmin bool) (*User, error) {
	id := idgen.New("us")
	var hash sql.NullString
	if passwordHash != "" {
		hash = sql.NullString{String: passwordHash, Valid: true}
	}
	_, err := db.Exec(`INSERT INTO users (id, username, email, password_hash, is_admin) VALUES (?, ?, ?, ?, ?)`,
		id, username, email, nullStringVal(hash), boolInt(isAdmin))
	if err != nil {
		return nil, err
	}
	return GetUserByID(db, id)
}

// CreateExternalUser inserts a user with no local password, created on
// first login via a trusted reverse-proxy identity header.
func CreateExternalUser(db *sql.DB, username string) (*User, error) {
	id := idgen.New("us")
	_, err := db.Exec(`INSERT INTO users (id, username, external_auth) VALUES (?, ?, 1)`, id, username)
	if err != nil {
		return nil, err
	}
	return GetUserByID(db, id)
}

func GetUserByID(db *sql.DB, id string) (*User, error) {
	return scanUser(db.QueryRow(`SELECT id, username, email, password_hash, is_admin, disabled, external_auth, created_at, last_login_at FROM users WHERE id = ?`, id))
}

func GetUserByUsername(db *sql.DB, username string) (*User, error) {
	return scanUser(db.QueryRow(`SELECT id, username, email, password_hash, is_admin, disabled, external_auth, created_at, last_login_at FROM users WHERE username = ?`, username))
}

func scanUser(row *sql.Row) (*User, error) {
	var u User
	var isAdmin, disabled, external int
	var createdAt string
	var lastLogin sql.NullString
	err := row.Scan(&u.ID, &u.Username, &u.Email, &u.PasswordHash, &isAdmin, &disabled, &external, &createdAt, &lastLogin)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, ErrNotFound
	}
	if err != nil {
		return nil, err
	}
	u.IsAdmin = isAdmin != 0
	u.Disabled = disabled != 0
	u.ExternalAuth = external != 0
	u.CreatedAt, _ = parseTime(createdAt)
	if lastLogin.Valid {
		if t, err := parseTime(lastLogin.String); err == nil {
			u.LastLoginAt = sql.NullTime{Time: t, Valid: true}
		}
	}
	return &u, nil
}

func ListUsers(db *sql.DB) ([]*User, error) {
	rows, err := db.Query(`SELECT id, username, email, password_hash, is_admin, disabled, external_auth, created_at, last_login_at FROM users ORDER BY username COLLATE NOCASE`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []*User
	for rows.Next() {
		var u User
		var isAdmin, disabled, external int
		var createdAt string
		var lastLogin sql.NullString
		if err := rows.Scan(&u.ID, &u.Username, &u.Email, &u.PasswordHash, &isAdmin, &disabled, &external, &createdAt, &lastLogin); err != nil {
			return nil, err
		}
		u.IsAdmin = isAdmin != 0
		u.Disabled = disabled != 0
		u.ExternalAuth = external != 0
		u.CreatedAt, _ = parseTime(createdAt)
		if lastLogin.Valid {
			if t, err := parseTime(lastLogin.String); err == nil {
				u.LastLoginAt = sql.NullTime{Time: t, Valid: true}
			}
		}
		out = append(out, &u)
	}
	return out, rows.Err()
}

func SetUserPassword(db *sql.DB, userID, passwordHash string) error {
	_, err := db.Exec(`UPDATE users SET password_hash = ? WHERE id = ?`, passwordHash, userID)
	return err
}

func SetUserDisabled(db *sql.DB, userID string, disabled bool) error {
	_, err := db.Exec(`UPDATE users SET disabled = ? WHERE id = ?`, boolInt(disabled), userID)
	return err
}

func SetUserAdmin(db *sql.DB, userID string, isAdmin bool) error {
	_, err := db.Exec(`UPDATE users SET is_admin = ? WHERE id = ?`, boolInt(isAdmin), userID)
	return err
}

func DeleteUser(db *sql.DB, userID string) error {
	_, err := db.Exec(`DELETE FROM users WHERE id = ?`, userID)
	return err
}

func TouchLastLogin(db *sql.DB, userID string) error {
	_, err := db.Exec(`UPDATE users SET last_login_at = strftime('%Y-%m-%dT%H:%M:%fZ','now') WHERE id = ?`, userID)
	return err
}

func boolInt(b bool) int {
	if b {
		return 1
	}
	return 0
}

func nullStringVal(s sql.NullString) any {
	if !s.Valid {
		return nil
	}
	return s.String
}

func parseTime(s string) (time.Time, error) {
	return time.Parse("2006-01-02T15:04:05.999999999Z", s)
}