package db

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

// 令牌类型常量
const (
	TokenTypeHOTP = "hotp"
	TokenTypeTOTP = "totp"
)

// Token 表示一个 OTP 令牌
type Token struct {
	ID        string    `json:"id"`
	UserID    string    `json:"user_id"`
	Issuer    string    `json:"issuer"`
	Account   string    `json:"account"`
	Secret    string    `json:"secret"`
	Type      string    `json:"type"`
	Counter   *int      `json:"counter,omitempty"`
	Period    int       `json:"period"`
	Digits    int       `json:"digits"`
	Algorithm string    `json:"algorithm"`
	Timestamp int64     `json:"timestamp"`
	CreatedAt time.Time `json:"created_at"`
	UpdatedAt time.Time `json:"updated_at"`
}

var (
	ErrTokenNotFound = errors.New("token not found")
	ErrInvalidToken  = errors.New("invalid token")
)

// SaveTokens 保存用户的令牌列表
func (db *DB) SaveTokens(userID string, tokens []Token) error {
	tx, err := db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()

	// 准备插入语句
	stmt, err := tx.Prepare(`
		INSERT INTO tokens (
			id, user_id, issuer, account, secret, type, counter, 
			period, digits, algorithm, timestamp, created_at, updated_at
		) VALUES (
			$1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13
		) ON CONFLICT (id, user_id) DO UPDATE SET
			issuer = EXCLUDED.issuer,
			account = EXCLUDED.account,
			secret = EXCLUDED.secret,
			type = EXCLUDED.type,
			counter = EXCLUDED.counter,
			period = EXCLUDED.period,
			digits = EXCLUDED.digits,
			algorithm = EXCLUDED.algorithm,
			timestamp = EXCLUDED.timestamp,
			updated_at = EXCLUDED.updated_at
	`)
	if err != nil {
		return err
	}
	defer stmt.Close()

	now := time.Now()
	for _, token := range tokens {
		// 确保algorithm字段有默认值
		algorithm := token.Algorithm
		if algorithm == "" {
			algorithm = "SHA1"
		}

		_, err = stmt.Exec(
			token.ID,
			userID,
			token.Issuer,
			token.Account,
			token.Secret,
			token.Type,
			token.Counter,
			token.Period,
			token.Digits,
			algorithm,
			token.Timestamp,
			now,
			now,
		)
		if err != nil {
			return err
		}
	}

	return tx.Commit()
}

// GetTokensByUserID 获取用户的所有令牌
func (db *DB) GetTokensByUserID(userID string) ([]Token, error) {
	rows, err := db.Query(`
		SELECT 
			id, user_id, issuer, account, secret, type, counter,
			period, digits, algorithm, timestamp, created_at, updated_at
		FROM tokens
		WHERE user_id = $1
		ORDER BY timestamp DESC
	`, userID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var tokens []Token
	for rows.Next() {
		var token Token
		err := rows.Scan(
			&token.ID,
			&token.UserID,
			&token.Issuer,
			&token.Account,
			&token.Secret,
			&token.Type,
			&token.Counter,
			&token.Period,
			&token.Digits,
			&token.Algorithm,
			&token.Timestamp,
			&token.CreatedAt,
			&token.UpdatedAt,
		)
		if err != nil {
			return nil, err
		}
		tokens = append(tokens, token)
	}

	if err = rows.Err(); err != nil {
		return nil, err
	}

	return tokens, nil
}

// DeleteToken 删除指定的令牌
func (db *DB) DeleteToken(userID, tokenID string) error {
	result, err := db.Exec(`
		DELETE FROM tokens
		WHERE user_id = $1 AND id = $2
	`, userID, tokenID)
	if err != nil {
		return err
	}

	affected, err := result.RowsAffected()
	if err != nil {
		return err
	}

	if affected == 0 {
		return ErrTokenNotFound
	}

	return nil
}

// UpdateTokenCounter 更新 HOTP 令牌的计数器
func (db *DB) UpdateTokenCounter(userID, tokenID string, counter int) error {
	result, err := db.Exec(`
		UPDATE tokens
		SET counter = $1, updated_at = $2
		WHERE user_id = $3 AND id = $4 AND type = $5
	`, counter, time.Now(), userID, tokenID, TokenTypeHOTP)
	if err != nil {
		return err
	}

	affected, err := result.RowsAffected()
	if err != nil {
		return err
	}

	if affected == 0 {
		return ErrTokenNotFound
	}

	return nil
}

// GetTokenByID 获取指定的令牌
func (db *DB) GetTokenByID(userID, tokenID string) (*Token, error) {
	var token Token
	err := db.QueryRow(`
		SELECT 
			id, user_id, issuer, account, secret, type, counter,
			period, digits, algorithm, timestamp, created_at, updated_at
		FROM tokens
		WHERE user_id = $1 AND id = $2
	`, userID, tokenID).Scan(
		&token.ID,
		&token.UserID,
		&token.Issuer,
		&token.Account,
		&token.Secret,
		&token.Type,
		&token.Counter,
		&token.Period,
		&token.Digits,
		&token.Algorithm,
		&token.Timestamp,
		&token.CreatedAt,
		&token.UpdatedAt,
	)

	if err == sql.ErrNoRows {
		return nil, ErrTokenNotFound
	}
	if err != nil {
		return nil, err
	}

	return &token, nil
}