package config

import (
	"bytes"
	"encoding/json"
	"errors"
	"io"
	"os"
	"path/filepath"
	"strings"
)

const defaultTencentSMSConfigFile = "/run/secrets/voice-runtime/tencent-sms.json"

type tencentSMSFile struct {
	TemplateParams map[string][]string `json:"template_params"`
	Enabled        *bool               `json:"enabled"`
	SecretID       string              `json:"secret_id"`
	SecretKey      string              `json:"secret_key"`
	SDKAppID       string              `json:"sdk_app_id"`
	SignName       string              `json:"sign_name"`
	Templates      map[string]string   `json:"templates"`
}

// Only API and worker consume SMS configuration. In particular, a mounted
// configuration must not enable onboarding in callbacks or other services.
func (c *OnboardingConfig) loadTencentSMSFile(serviceName string) error {
	if serviceName != "api" && serviceName != "worker" {
		return nil
	}
	path := strings.TrimSpace(os.Getenv("TENCENT_SMS_CONFIG_FILE"))
	explicit := path != ""
	if !explicit {
		path = defaultTencentSMSConfigFile
		// The conventional mount exists only on Unix hosts/containers. Windows
		// development can still opt in with an explicit absolute file path.
		if !filepath.IsAbs(path) {
			return nil
		}
	}
	return c.readTencentSMSFile(path, explicit)
}

func (c *OnboardingConfig) readTencentSMSFile(path string, required bool) error {
	if !filepath.IsAbs(path) {
		return errors.New("TENCENT_SMS_CONFIG_FILE must be an absolute path")
	}
	file, err := os.Open(filepath.Clean(path))
	if errors.Is(err, os.ErrNotExist) && !required {
		return nil
	}
	if err != nil {
		return errors.New("Tencent SMS configuration file is unavailable")
	}
	defer file.Close()
	info, err := file.Stat()
	if err != nil || !info.Mode().IsRegular() || info.Size() > 64*1024 {
		return errors.New("Tencent SMS configuration must be a regular file of at most 64 KiB")
	}
	raw, err := io.ReadAll(io.LimitReader(file, 64*1024+1))
	if err != nil || len(raw) > 64*1024 {
		return errors.New("Tencent SMS configuration file could not be read")
	}
	// Accept UTF-8 BOM from Windows editors. Never include raw JSON or parser
	// errors in startup errors: unknown fields may accidentally contain secrets.
	raw = bytes.TrimPrefix(raw, []byte{0xef, 0xbb, 0xbf})
	decoder := json.NewDecoder(bytes.NewReader(raw))
	decoder.DisallowUnknownFields()
	var in tencentSMSFile
	if err := decoder.Decode(&in); err != nil || in.Enabled == nil {
		return errors.New("Tencent SMS configuration must match the JSON template and include enabled")
	}
	if err := decoder.Decode(new(any)); err != io.EOF {
		return errors.New("Tencent SMS configuration must contain exactly one JSON object")
	}
	for key, value := range in.Templates {
		if key != "login" && key != "register" && key != "change_password" && key != "change_phone" {
			return errors.New("Tencent SMS template names must be login, register, change_password or change_phone")
		}
		in.Templates[key] = strings.TrimSpace(value)
	}
	c.SMSProvider = "tencent"
	c.SMSLoginEnabled = *in.Enabled
	c.TencentSMSSecretID = strings.TrimSpace(in.SecretID)
	c.TencentSMSSecretKey = strings.TrimSpace(in.SecretKey)
	c.TencentSMSAppID = strings.TrimSpace(in.SDKAppID)
	c.TencentSMSSignName = strings.TrimSpace(in.SignName)
	c.TencentSMSTemplateID = ""
	c.TencentSMSTemplates = in.Templates
	c.TencentSMSTemplateParams = in.TemplateParams
	return nil
}