backend/internal/config/database.go

package config

import "fmt"

// DatabaseConfig 数据库配置
type DatabaseConfig struct {
	Type                 string                   `mapstructure:"type"`
	SQLite               SQLiteConfig             `mapstructure:"sqlite"`
	Postgres             PostgresConfig           `mapstructure:"postgres"`
	MaxIdleConns         int                      `mapstructure:"max_idle_conns"`
	MaxOpenConns         int                      `mapstructure:"max_open_conns"`
	LogLevel             string                   `mapstructure:"log_level"`
	SlowThresholdMs      int                      `mapstructure:"slow_threshold_ms"`
	IgnoreRecordNotFound bool                     `mapstructure:"ignore_record_not_found"`
	ParameterizedQueries bool                     `mapstructure:"parameterized_queries"`
	// 读写分离：单副本配置（支持环境变量，如 APP_DATABASE_REPLICA_HOST）
	Replica        PostgresConfig `mapstructure:"replica"`
	// 读写分离：多副本配置（仅 YAML 支持，环境变量无法覆盖切片结构体）
	Replicas       []PostgresConfig `mapstructure:"replicas"`
	ReplicaPolicy  string           `mapstructure:"replica_policy"`
	ReplicaMaxIdle int              `mapstructure:"replica_max_idle_conns"`
	ReplicaMaxOpen int              `mapstructure:"replica_max_open_conns"`
}

// SQLiteConfig SQLite 配置
type SQLiteConfig struct {
	Path string `mapstructure:"path"`
}

// PostgresConfig PostgreSQL 配置（主库和副本共用）
type PostgresConfig struct {
	Host     string `mapstructure:"host"`
	Port     int    `mapstructure:"port"`
	User     string `mapstructure:"user"`
	Password string `mapstructure:"password"`
	DBName   string `mapstructure:"dbname"`
	SSLMode  string `mapstructure:"sslmode"`
}

// DSN 返回 PostgreSQL 连接字符串
func (d PostgresConfig) DSN() string {
	return fmt.Sprintf(
		"host=%s port=%d user=%s password=%s dbname=%s sslmode=%s",
		d.Host, d.Port, d.User, d.Password, d.DBName, d.SSLMode,
	)
}

// HasReplica 返回是否配置了读副本（单副本或多副本）
func (d DatabaseConfig) HasReplica() bool {
	return d.Replica.Host != "" || len(d.Replicas) > 0
}

// AllReplicas 返回所有读副本配置（合并单副本 + 多副本）
func (d DatabaseConfig) AllReplicas() []PostgresConfig {
	var result []PostgresConfig
	if d.Replica.Host != "" {
		result = append(result, d.Replica)
	}
	result = append(result, d.Replicas...)
	return result
}