package store

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

	"daili/internal/pw"
)

// User 管理员账户。
type User struct {
	ID          int64
	Username    string
	DisplayName string
	IsActive    bool
	CreatedAt   string
	LastLoginAt string
}

func scanUser(row interface {
	Scan(dest ...any) error
}) (*User, error) {
	var u User
	var active int
	var last sql.NullString
	if err := row.Scan(&u.ID, &u.Username, &u.DisplayName, &active, &u.CreatedAt, &last); err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return nil, ErrNotFound
		}
		return nil, err
	}
	u.IsActive = active == 1
	u.LastLoginAt = last.String
	return &u, nil
}

const userCols = `id, username, display_name, is_active, created_at, IFNULL(last_login_at,'')`

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

// CreateUser 新建账户。
func (db *DB) CreateUser(username, displayName, password string) (*User, error) {
	hash, err := pw.Hash(password)
	if err != nil {
		return nil, err
	}
	now := nowStamp()
	res, err := db.sql.Exec(`INSERT INTO users(username, display_name, password_hash, is_active, created_at)
		VALUES(?,?,?,1,?)`, username, displayName, hash, now)
	if err != nil {
		if isUnique(err) {
			return nil, ErrDuplicate
		}
		return nil, err
	}
	id, _ := res.LastInsertId()
	return &User{ID: id, Username: username, DisplayName: displayName, IsActive: true, CreatedAt: now}, nil
}

// Authenticate 校验用户名口令。
func (db *DB) Authenticate(username, password string) (*User, error) {
	var hash string
	var active int
	var id int64
	err := db.sql.QueryRow(`SELECT id, password_hash, is_active FROM users WHERE username=?`, username).
		Scan(&id, &hash, &active)
	if err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return nil, ErrNotFound
		}
		return nil, err
	}
	if active != 1 || !pw.Verify(password, hash) {
		return nil, ErrNotFound
	}
	_, _ = db.sql.Exec(`UPDATE users SET last_login_at=? WHERE id=?`, nowStamp(), id)
	return db.UserByID(id)
}

// UserByID 按 ID 取账户。
func (db *DB) UserByID(id int64) (*User, error) {
	return scanUser(db.sql.QueryRow(`SELECT `+userCols+` FROM users WHERE id=?`, id))
}

// UserByUsername 按用户名取账户。
func (db *DB) UserByUsername(name string) (*User, error) {
	return scanUser(db.sql.QueryRow(`SELECT `+userCols+` FROM users WHERE username=?`, name))
}

// ListUsers 列出账户。
func (db *DB) ListUsers() ([]User, error) {
	rows, err := db.sql.Query(`SELECT ` + userCols + ` FROM users ORDER BY id`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []User
	for rows.Next() {
		u, err := scanUser(rows)
		if err != nil {
			return nil, err
		}
		out = append(out, *u)
	}
	return out, rows.Err()
}

// UpdatePassword 修改口令。
func (db *DB) UpdatePassword(userID int64, password string) error {
	hash, err := pw.Hash(password)
	if err != nil {
		return err
	}
	_, err = db.sql.Exec(`UPDATE users SET password_hash=? WHERE id=?`, hash, userID)
	return err
}

// SetUserActive 启用/停用账户。
func (db *DB) SetUserActive(userID int64, active bool) error {
	v := 0
	if active {
		v = 1
	}
	_, err := db.sql.Exec(`UPDATE users SET is_active=? WHERE id=?`, v, userID)
	return err
}

// ---------- 会话 ----------

// CreateSession 新建登录会话。
func (db *DB) CreateSession(token string, userID int64, ttl time.Duration, ip string) error {
	now := time.Now()
	_, err := db.sql.Exec(`INSERT INTO sessions(token,user_id,created_at,expires_at,ip) VALUES(?,?,?,?,?)`,
		token, userID, now.Format("2006-01-02 15:04:05"), now.Add(ttl).Format("2006-01-02 15:04:05"), ip)
	return err
}

// SessionUser 通过令牌取账户，过期则返回 ErrNotFound。
func (db *DB) SessionUser(token string) (*User, error) {
	var userID int64
	var expires string
	err := db.sql.QueryRow(`SELECT user_id, expires_at FROM sessions WHERE token=?`, token).Scan(&userID, &expires)
	if err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return nil, ErrNotFound
		}
		return nil, err
	}
	exp, err := time.ParseInLocation("2006-01-02 15:04:05", expires, time.Local)
	if err != nil || exp.Before(time.Now()) {
		_ = db.DeleteSession(token)
		return nil, ErrNotFound
	}
	u, err := db.UserByID(userID)
	if err != nil {
		return nil, err
	}
	if !u.IsActive {
		return nil, ErrNotFound
	}
	return u, nil
}

// DeleteSession 删除会话。
func (db *DB) DeleteSession(token string) error {
	_, err := db.sql.Exec(`DELETE FROM sessions WHERE token=?`, token)
	return err
}

// PurgeSessions 清理过期会话。
func (db *DB) PurgeSessions() {
	_, _ = db.sql.Exec(`DELETE FROM sessions WHERE expires_at < ?`, nowStamp())
}