package config

import (
	"os"
	"strconv"
	"strings"
	"time"
)

// Config 定义服务运行配置。
// AI 调用统一走 OpenAI 兼容协议，上游地址和鉴权由环境变量提供。
type Config struct {
	Port           string
	ProviderName   string
	AIBaseURL      string
	AIChatPath     string
	AIAPIKey       string
	AIModel        string
	AITimeout      time.Duration
	AllowedOrigins []string
}

// Load 从环境变量装载运行配置。
// 未提供的字段使用保守默认值，确保本地开发可以直接启动服务。
func Load() Config {
	return Config{
		Port:           getenv("SERVER_PORT", "8080"),
		ProviderName:   getenv("AI_PROVIDER_NAME", "OpenAI Compatible"),
		AIBaseURL:      strings.TrimRight(getenv("AI_BASE_URL", "https://api.openai.com"), "/"),
		AIChatPath:     normalizePath(getenv("AI_CHAT_PATH", "/v1/chat/completions")),
		AIAPIKey:       strings.TrimSpace(os.Getenv("AI_API_KEY")),
		AIModel:        strings.TrimSpace(os.Getenv("AI_MODEL")),
		AITimeout:      time.Duration(getenvInt("AI_TIMEOUT_SECONDS", 60)) * time.Second,
		AllowedOrigins: splitOrigins(getenv("WEB_ALLOWED_ORIGINS", "http://127.0.0.1:5173,http://localhost:5173")),
	}
}

// AIEnabled 判断 AI 服务是否已具备调用条件。
func (c Config) AIEnabled() bool {
	return c.AIAPIKey != "" && c.AIModel != "" && c.AIBaseURL != ""
}

func getenv(key string, fallback string) string {
	value := strings.TrimSpace(os.Getenv(key))
	if value == "" {
		return fallback
	}
	return value
}

func getenvInt(key string, fallback int) int {
	value := strings.TrimSpace(os.Getenv(key))
	if value == "" {
		return fallback
	}

	parsed, err := strconv.Atoi(value)
	if err != nil || parsed <= 0 {
		return fallback
	}

	return parsed
}

func normalizePath(path string) string {
	if path == "" {
		return "/v1/chat/completions"
	}
	if strings.HasPrefix(path, "/") {
		return path
	}
	return "/" + path
}

func splitOrigins(raw string) []string {
	parts := strings.Split(raw, ",")
	origins := make([]string, 0, len(parts))

	for _, part := range parts {
		origin := strings.TrimSpace(part)
		if origin != "" {
			origins = append(origins, origin)
		}
	}

	if len(origins) == 0 {
		return []string{"http://127.0.0.1:5173", "http://localhost:5173"}
	}

	return origins
}