package sms

import (
	"context"
	"errors"
	"fmt"
	"strings"
	"sync"
)

const (
	ServiceAliyun  = "1"
	ServiceTencent = "2"
)

var (
	ErrProviderNotFound = errors.New("未选择有效的短信发送供应商")
	ErrInvalidRequest   = errors.New("短信请求参数不正确")
)

// Config contains the provider credentials and template configuration.
// serviceType: 1=Aliyun, 2=Tencent Cloud.
type Config struct {
	ServiceType     string `json:"serviceType"     yaml:"serviceType"`
	RegionID        string `json:"regionId"        yaml:"regionId"`
	AccessKeyID     string `json:"accessKeyId"     yaml:"accessKeyId"`
	AccessKeySecret string `json:"accessKeySecret" yaml:"accessKeySecret"`
	SDKAppID        string `json:"sdkAppId"        yaml:"sdkAppId"`
	SignName        string `json:"signName"        yaml:"signName"`
	TemplateID      string `json:"templateId"      yaml:"templateId"`
}

type Message struct {
	PhoneNumber string `json:"phoneNumber"`
	MsgContent  string `json:"msgContent"`
}

type Result struct {
	Code    int            `json:"code"`
	Message string         `json:"message"`
	Data    map[string]any `json:"data,omitempty"`
}

type Provider interface {
	Send(context.Context, Config, Message) (Result, error)
}

type Registry struct {
	mu            sync.RWMutex
	providers     map[string]Provider
	defaultConfig Config
}

// NewRegistry 创建一个无默认配置的注册表。
func NewRegistry() *Registry {
	return &Registry{providers: make(map[string]Provider)}
}

// NewRegistryWithDefault 创建一个带默认配置的注册表。调用方请求中未显式提供的字段
// 将回退到 defaultConfig（例如供应商凭证与签名由短信服务自身环境变量注入）。
func NewRegistryWithDefault(dc Config) *Registry {
	return &Registry{providers: make(map[string]Provider), defaultConfig: dc}
}

func (r *Registry) Register(serviceType string, provider Provider) {
	r.mu.Lock()
	defer r.mu.Unlock()
	r.providers[serviceType] = provider
}

func (r *Registry) Send(ctx context.Context, config Config, message Message) (Result, error) {
	// 回退默认值：请求中未提供的字段使用短信服务自身的默认配置。
	config = mergeConfig(r.defaultConfig, config)
	if err := Validate(config, message); err != nil {
		return Result{Code: 400, Message: err.Error()}, err
	}

	r.mu.RLock()
	provider, ok := r.providers[config.ServiceType]
	r.mu.RUnlock()
	if !ok {
		return Result{Code: 400, Message: ErrProviderNotFound.Error()}, ErrProviderNotFound
	}
	return provider.Send(ctx, config, message)
}

func Validate(config Config, message Message) error {
	missing := make([]string, 0, 6)
	if strings.TrimSpace(config.ServiceType) == "" {
		missing = append(missing, "config.serviceType")
	}
	if strings.TrimSpace(config.AccessKeyID) == "" {
		missing = append(missing, "config.accessKeyId")
	}
	if strings.TrimSpace(config.AccessKeySecret) == "" {
		missing = append(missing, "config.accessKeySecret")
	}
	if strings.TrimSpace(config.SignName) == "" {
		missing = append(missing, "config.signName")
	}
	if strings.TrimSpace(config.TemplateID) == "" {
		missing = append(missing, "config.templateId")
	}
	if strings.TrimSpace(message.PhoneNumber) == "" {
		missing = append(missing, "params.phoneNumber")
	}
	if config.ServiceType == ServiceTencent && strings.TrimSpace(config.SDKAppID) == "" {
		missing = append(missing, "config.sdkAppId")
	}
	if len(missing) != 0 {
		return fmt.Errorf("%w: 缺少 %s", ErrInvalidRequest, strings.Join(missing, ", "))
	}
	return nil
}

// mergeConfig 用 defaultConfig 填充 config 中的空字段，调用方显式值优先。
func mergeConfig(defaultConfig, config Config) Config {
	if config.ServiceType == "" {
		config.ServiceType = defaultConfig.ServiceType
	}
	if config.RegionID == "" {
		config.RegionID = defaultConfig.RegionID
	}
	if config.AccessKeyID == "" {
		config.AccessKeyID = defaultConfig.AccessKeyID
	}
	if config.AccessKeySecret == "" {
		config.AccessKeySecret = defaultConfig.AccessKeySecret
	}
	if config.SDKAppID == "" {
		config.SDKAppID = defaultConfig.SDKAppID
	}
	if config.SignName == "" {
		config.SignName = defaultConfig.SignName
	}
	if config.TemplateID == "" {
		config.TemplateID = defaultConfig.TemplateID
	}
	return config
}

func SplitAndTrim(value, separator string) []string {
	parts := strings.Split(value, separator)
	result := make([]string, 0, len(parts))
	for _, part := range parts {
		if item := strings.TrimSpace(part); item != "" {
			result = append(result, item)
		}
	}
	return result
}