package main

import (
	cryptorand "crypto/rand"
	"errors"
	"fmt"
	"net/url"
	"os"
	"strings"
)

// ASR-only subset of the reference configuration. No LLM/TTS fields are imported.
type agentCfg struct {
	BailianKey, BailianWssBaseURL                                  string
	VolcAppKey, VolcAppID, VolcAccessToken, VolcResourceID, VolcWS string
}

type config struct {
	bailianKey, bailianBase, funASRKey, funASRBase           string
	volcAppKey, volcAppID, volcToken, volcResourceID, volcWS string
}

func env(key, fallback string) string {
	if v := os.Getenv(key); v != "" {
		return v
	}
	return fallback
}

func loadConfig() config {
	key := os.Getenv("BAILIAN_API_KEY")
	return config{
		bailianKey:  key,
		bailianBase: env("BAILIAN_WS", "wss://dashscope.aliyuncs.com/api-ws/v1/inference/"),
		funASRKey:   env("FUNASR_API_KEY", key),
		funASRBase:  env("FUNASR_WS", "wss://dashscope.aliyuncs.com/api-ws/v1/inference/"),
		volcAppKey:  os.Getenv("VOLC_APP_KEY"), volcAppID: os.Getenv("VOLC_APP_ID"),
		volcToken:      os.Getenv("VOLC_ACCESS_TOKEN"),
		volcResourceID: env("VOLC_RESOURCE_ID", "volc.bigasr.sauc.duration"),
		volcWS:         env("VOLC_WS", "wss://openspeech.bytedance.com/api/v3/sauc/bigmodel"),
	}
}

func validateConfig(token, origin string, cfg config) error {
	if len(token) < 32 || strings.HasPrefix(token, "CHANGE_ME") {
		return errors.New("ASR_WEB_TOKEN must be at least 32 characters and not a placeholder")
	}
	for _, r := range token {
		if !(r >= 'a' && r <= 'z' || r >= 'A' && r <= 'Z' || r >= '0' && r <= '9' || r == '-' || r == '_') {
			return errors.New("ASR_WEB_TOKEN must use URL-safe alphanumeric characters")
		}
	}
	if origin != "" {
		u, err := url.Parse(origin)
		if err != nil || (u.Scheme != "https" && u.Scheme != "http") || u.Host == "" || u.User != nil || u.Path != "" || u.RawQuery != "" || u.Fragment != "" {
			return errors.New("PUBLIC_ORIGIN must be an exact http(s) origin without a path")
		}
	}
	for _, endpoint := range []string{cfg.bailianBase, cfg.funASRBase, cfg.volcWS} {
		u, err := url.Parse(endpoint)
		if err != nil || u.Scheme != "wss" || u.Host == "" || u.User != nil {
			return errors.New("provider endpoints must use wss without embedded credentials")
		}
	}
	return nil
}

func uuid() (string, error) {
	b := make([]byte, 16)
	count, err := cryptorand.Read(b)
	if err != nil || count != len(b) {
		return "", errors.New("secure random unavailable")
	}
	b[6] = b[6]&15 | 64
	b[8] = b[8]&63 | 128
	return fmt.Sprintf("%x-%x-%x-%x-%x", b[:4], b[4:6], b[6:8], b[8:10], b[10:]), nil
}