package main

import (
	"fmt"
	"io"
	"net"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"time"

	"git.asio.asia/nixevol/NixMsg/internal/config"
)

// healthcheck 请求本机 /healthz，成功退出 0。给 Docker HEALTHCHECK 用。
func cmdHealthcheck(_ []string) error {
	cfgPath := config.PathFromEnv()
	cfg, err := config.Load(cfgPath)
	if err != nil {
		// 无配置时仍尝试 data_dir 默认值下的 listen.addr
		cfg = config.Default()
	}
	addr, err := resolveHealthAddr(cfg.DataDir, cfg.Listen)
	if err != nil {
		return err
	}
	url := "http://" + addr + "/healthz"
	client := &http.Client{Timeout: 3 * time.Second}
	resp, err := client.Get(url)
	if err != nil {
		return fmt.Errorf("healthcheck %s: %w", url, err)
	}
	defer func() { _ = resp.Body.Close() }()
	_, _ = io.Copy(io.Discard, resp.Body)
	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("healthcheck %s: status %d", url, resp.StatusCode)
	}
	return nil
}

func resolveHealthAddr(dataDir, listen string) (string, error) {
	path := filepath.Join(dataDir, "listen.addr")
	if b, err := os.ReadFile(path); err == nil {
		addr := strings.TrimSpace(string(b))
		if addr != "" {
			return rewriteLoopback(addr), nil
		}
	}
	if listen == "" {
		return "", fmt.Errorf("no listen.addr and empty listen")
	}
	host, port, err := net.SplitHostPort(listen)
	if err != nil {
		// listen 可能是 ":7443"
		if strings.HasPrefix(listen, ":") {
			return "127.0.0.1" + listen, nil
		}
		return "", fmt.Errorf("parse listen %q: %w", listen, err)
	}
	if host == "" || host == "0.0.0.0" || host == "::" {
		host = "127.0.0.1"
	}
	return net.JoinHostPort(host, port), nil
}

func rewriteLoopback(addr string) string {
	host, port, err := net.SplitHostPort(addr)
	if err != nil {
		return addr
	}
	if host == "" || host == "0.0.0.0" || host == "::" {
		host = "127.0.0.1"
	}
	return net.JoinHostPort(host, port)
}