// Package service 业务服务层。
package service

import (
	"encoding/json"
	"fmt"
	"net/http"
	"os"
	"strings"
	"sync"
	"time"
)

// Release 对外暴露的最新版本信息。
type Release struct {
	Version string `json:"version"`
	PageURL string `json:"page_url"`
	MacOS   string `json:"macos_url,omitempty"`
	Windows string `json:"windows_url,omitempty"`
	Source  string `json:"source"` // gitea | fallback
}

// ReleaseService 代理 gitea Releases API，带缓存与静态回退。
type ReleaseService struct {
	giteaBase string
	repo      string
	fallback  Release

	mu       sync.Mutex
	cached   *Release
	cachedAt time.Time
	ttl      time.Duration
	client   *http.Client
}

func NewReleaseService() *ReleaseService {
	base := envOr("SUNDYNIX_GITEA_BASE", "https://git.sundynix.cn")
	repo := envOr("SUNDYNIX_RELEASE_REPO", "sundynix/sundynix-agentix")
	pageURL := fmt.Sprintf("%s/%s/releases", base, repo)
	return &ReleaseService{
		giteaBase: base,
		repo:      repo,
		fallback: Release{
			Version: envOr("SUNDYNIX_FALLBACK_VERSION", "v0.1.2"),
			PageURL: pageURL,
			Source:  "fallback",
		},
		ttl:    10 * time.Minute,
		client: &http.Client{Timeout: 8 * time.Second},
	}
}

// Latest 返回最新 release；gitea 不可达或无发布时回退静态配置。
func (s *ReleaseService) Latest() Release {
	s.mu.Lock()
	defer s.mu.Unlock()
	if s.cached != nil && time.Since(s.cachedAt) < s.ttl {
		return *s.cached
	}
	rel := s.fetch()
	s.cached = &rel
	s.cachedAt = time.Now()
	return rel
}

type giteaAsset struct {
	Name string `json:"name"`
	URL  string `json:"browser_download_url"`
}

type giteaRelease struct {
	TagName    string       `json:"tag_name"`
	HTMLURL    string       `json:"html_url"`
	Draft      bool         `json:"draft"`
	Prerelease bool         `json:"prerelease"`
	Assets     []giteaAsset `json:"assets"`
}

func (s *ReleaseService) fetch() Release {
	url := fmt.Sprintf("%s/api/v1/repos/%s/releases?limit=5", s.giteaBase, s.repo)
	resp, err := s.client.Get(url)
	if err != nil {
		return s.fallback
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		return s.fallback
	}

	var list []giteaRelease
	if err := json.NewDecoder(resp.Body).Decode(&list); err != nil {
		return s.fallback
	}
	for _, r := range list {
		if r.Draft || r.Prerelease {
			continue
		}
		rel := Release{
			Version: r.TagName,
			PageURL: r.HTMLURL,
			Source:  "gitea",
		}
		if rel.PageURL == "" {
			rel.PageURL = s.fallback.PageURL
		}
		for _, a := range r.Assets {
			name := strings.ToLower(a.Name)
			switch {
			case strings.HasSuffix(name, ".dmg"),
				strings.Contains(name, "darwin"),
				strings.Contains(name, "macos"):
				rel.MacOS = a.URL
			case strings.HasSuffix(name, ".exe"),
				strings.Contains(name, "windows"):
				rel.Windows = a.URL
			}
		}
		return rel
	}
	return s.fallback
}

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