package store

import (
	"database/sql"
	"fmt"
	"time"

	_ "github.com/lib/pq"
)

// User 用户模型
type User struct {
	ID           int       `json:"id"`
	Username     string    `json:"username"`
	Nickname     string    `json:"nickname"`
	PasswordHash string    `json:"-"`
	IsAdmin      bool      `json:"is_admin"`
	CreatedAt    time.Time `json:"created_at"`
	UpdatedAt    time.Time `json:"updated_at"`
}

// CreateUsersTable 创建 users 表（如果不存在）
func CreateUsersTable(db *sql.DB) error {
	query := `CREATE TABLE IF NOT EXISTS users (
		id SERIAL PRIMARY KEY,
		username VARCHAR(255) UNIQUE NOT NULL,
		nickname VARCHAR(255) DEFAULT '',
		password_hash VARCHAR(255) NOT NULL,
		is_admin BOOLEAN DEFAULT FALSE,
		created_at TIMESTAMPTZ DEFAULT NOW(),
		updated_at TIMESTAMPTZ DEFAULT NOW()
	)`

	if _, err := db.Exec(query); err != nil {
		return fmt.Errorf("创建 users 表失败: %w", err)
	}

	// 迁移：为已有 users 表添加 nickname 列
	db.Exec(`ALTER TABLE users ADD COLUMN IF NOT EXISTS nickname VARCHAR(255) DEFAULT ''`)

	// 创建索引
	indexQueries := []string{
		`CREATE INDEX IF NOT EXISTS idx_users_username ON users(username)`,
	}

	for _, q := range indexQueries {
		if _, err := db.Exec(q); err != nil {
			return fmt.Errorf("创建 users 索引失败: %w", err)
		}
	}

	return nil
}

// GetUserByUsername 按用户名查询用户
// 如果用户不存在，返回 (nil, nil)
func GetUserByUsername(db *sql.DB, username string) (*User, error) {
	var u User
	err := db.QueryRow(
		`SELECT id, username, COALESCE(nickname, '') as nickname, password_hash, is_admin, created_at, updated_at
		 FROM users WHERE username = $1`,
		username,
	).Scan(&u.ID, &u.Username, &u.Nickname, &u.PasswordHash, &u.IsAdmin, &u.CreatedAt, &u.UpdatedAt)

	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, fmt.Errorf("查询用户失败: %w", err)
	}

	return &u, nil
}

// ListUsers 列出所有用户
func ListUsers(db *sql.DB) ([]User, error) {
	rows, err := db.Query(
		`SELECT id, username, COALESCE(nickname, '') as nickname, password_hash, is_admin, created_at, updated_at
		 FROM users ORDER BY id`,
	)
	if err != nil {
		return nil, fmt.Errorf("查询用户列表失败: %w", err)
	}
	defer rows.Close()

	var users []User
	for rows.Next() {
		var u User
		if err := rows.Scan(&u.ID, &u.Username, &u.Nickname, &u.PasswordHash, &u.IsAdmin, &u.CreatedAt, &u.UpdatedAt); err != nil {
			return nil, fmt.Errorf("扫描用户行失败: %w", err)
		}
		users = append(users, u)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("遍历用户行出错: %w", err)
	}
	if users == nil {
		users = []User{}
	}
	return users, nil
}

// DeleteUser 按 ID 删除用户
func DeleteUser(db *sql.DB, userID int) error {
	result, err := db.Exec(`DELETE FROM users WHERE id = $1`, userID)
	if err != nil {
		return fmt.Errorf("删除用户失败: %w", err)
	}
	affected, _ := result.RowsAffected()
	if affected == 0 {
		return fmt.Errorf("用户不存在 (id=%d)", userID)
	}
	return nil
}

// CreateUser 创建新用户
func CreateUser(db *sql.DB, username, nickname, passwordHash string, isAdmin bool) (*User, error) {
	now := time.Now()
	var u User
	err := db.QueryRow(
		`INSERT INTO users (username, nickname, password_hash, is_admin, created_at, updated_at)
		 VALUES ($1, $2, $3, $4, $5, $5)
		 ON CONFLICT (username) DO UPDATE SET nickname = $2, updated_at = $5
		 RETURNING id, username, COALESCE(nickname, '') as nickname, password_hash, is_admin, created_at, updated_at`,
		username, nickname, passwordHash, isAdmin, now,
	).Scan(&u.ID, &u.Username, &u.Nickname, &u.PasswordHash, &u.IsAdmin, &u.CreatedAt, &u.UpdatedAt)

	if err != nil {
		return nil, fmt.Errorf("创建用户失败: %w", err)
	}

	return &u, nil
}