package pipeline

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"net/url"
	"regexp"
	"strings"
	"time"

	"spider/internal/extractor"
	"spider/internal/model"

	"gorm.io/gorm"
)

// GithubPhase Phase 3: GitHub README 挖掘
type GithubPhase struct {
	db       *gorm.DB
	token    string // GitHub token（可选）
	settings Settings
	reporter ProgressReporter
	http     *http.Client
}

// NewGithubPhase creates a new GithubPhase.
func NewGithubPhase(db *gorm.DB, token string, settings Settings) *GithubPhase {
	return &GithubPhase{
		db:       db,
		token:    token,
		settings: settings,
		http:     &http.Client{Timeout: 15 * time.Second},
	}
}

func (p *GithubPhase) Name() string { return "github" }

func (p *GithubPhase) Run(ctx context.Context, task *model.Task, opts *Options) error {
	// GitHub 搜索 query：从 managed_keywords 取前 10 个生成 query
	var keywords []model.ManagedKeyword
	p.db.Where("status = ?", "active").Limit(10).Find(&keywords)

	queries := []string{}
	for _, kw := range keywords {
		queries = append(queries, fmt.Sprintf("%s telegram", kw.Keyword))
	}

	itemLimit := 50 // 默认处理 50 个 repo
	if opts.TestRun != nil && opts.TestRun.ItemLimit > 0 {
		itemLimit = opts.TestRun.ItemLimit
	}

	total := len(queries)
	found := 0

	reposPerQuery := 1
	if len(queries) > 0 {
		reposPerQuery = itemLimit/len(queries) + 1
	}

	for i, query := range queries {
		if isContextDone(ctx) {
			break
		}
		if p.reporter != nil {
			p.reporter("github", i+1, total, "GitHub搜索: "+query)
		}

		repos, err := p.searchRepos(ctx, query, reposPerQuery)
		if err != nil {
			log.Printf("[github] search err: %v", err)
			continue
		}

		for _, repo := range repos {
			if isContextDone(ctx) {
				break
			}

			readme, err := p.fetchReadme(ctx, repo)
			if err != nil {
				continue
			}

			// 过滤：README 前 5000 字必须含中文
			preview := readme
			if len(preview) > 5000 {
				preview = preview[:5000]
			}
			if !extractor.ContainsChinese(preview, 0) {
				continue
			}

			// 提取 t.me 链接
			links := extractTMeLinks(readme)
			for _, link := range links {
				// 前后 200 字必须含中文
				idx := strings.Index(readme, link)
				if idx < 0 {
					continue
				}
				start := idx - 200
				if start < 0 {
					start = 0
				}
				end := idx + len(link) + 200
				if end > len(readme) {
					end = len(readme)
				}
				context200 := readme[start:end]
				if !extractor.ContainsChinese(context200, 0) {
					continue
				}

				username := extractTGUsernameFromLink(link)
				if username == "" {
					continue
				}

				ch := &model.Channel{
					Username:     username,
					Source:       "github",
					SourceDetail: repo,
					Status:       "pending",
				}
				result := p.db.Where(model.Channel{Username: username}).FirstOrCreate(ch)
				if result.RowsAffected > 0 {
					found++
				}
			}

			// repo 间 sleep 2s
			select {
			case <-ctx.Done():
				return nil
			case <-time.After(2 * time.Second):
			}
		}

		// query 间 sleep 5s
		select {
		case <-ctx.Done():
			return nil
		case <-time.After(5 * time.Second):
		}
	}

	log.Printf("[github] done: %d channels found", found)
	return nil
}

// searchRepos 通过 GitHub Search API 搜索仓库
func (p *GithubPhase) searchRepos(ctx context.Context, query string, limit int) ([]string, error) {
	perPage := limit
	if perPage > 30 {
		perPage = 30
	}
	apiURL := fmt.Sprintf("https://api.github.com/search/repositories?q=%s&sort=stars&per_page=%d",
		url.QueryEscape(query), perPage)

	req, err := http.NewRequestWithContext(ctx, "GET", apiURL, nil)
	if err != nil {
		return nil, err
	}
	req.Header.Set("Accept", "application/vnd.github.v3+json")
	if p.token != "" {
		req.Header.Set("Authorization", "token "+p.token)
	}

	resp, err := p.http.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	var result struct {
		Items []struct {
			FullName string `json:"full_name"`
		} `json:"items"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
		return nil, err
	}

	var repos []string
	for _, item := range result.Items {
		repos = append(repos, item.FullName)
	}
	return repos, nil
}

// fetchReadme 下载 README.md（先尝试 main 分支，失败则尝试 master）
func (p *GithubPhase) fetchReadme(ctx context.Context, fullName string) (string, error) {
	rawURL := fmt.Sprintf("https://raw.githubusercontent.com/%s/main/README.md", fullName)
	req, err := http.NewRequestWithContext(ctx, "GET", rawURL, nil)
	if err != nil {
		return "", err
	}
	if p.token != "" {
		req.Header.Set("Authorization", "token "+p.token)
	}

	resp, err := p.http.Do(req)
	if err != nil {
		return "", err
	}
	defer resp.Body.Close()

	if resp.StatusCode == 404 {
		// 尝试 master 分支
		masterURL := strings.Replace(rawURL, "/main/", "/master/", 1)
		req2, err := http.NewRequestWithContext(ctx, "GET", masterURL, nil)
		if err != nil {
			return "", err
		}
		if p.token != "" {
			req2.Header.Set("Authorization", "token "+p.token)
		}
		resp2, err := p.http.Do(req2)
		if err != nil {
			return "", err
		}
		defer resp2.Body.Close()
		data, _ := io.ReadAll(resp2.Body)
		return string(data), nil
	}

	data, _ := io.ReadAll(resp.Body)
	return string(data), nil
}

// extractTMeLinks 从文本中提取所有 t.me 链接
func extractTMeLinks(text string) []string {
	re := regexp.MustCompile(`https?://t(?:elegram)?\.me/[a-zA-Z][a-zA-Z0-9_]{4,31}`)
	return re.FindAllString(text, -1)
}

// extractTGUsernameFromLink 从 t.me/xxx 链接提取用户名
func extractTGUsernameFromLink(link string) string {
	re := regexp.MustCompile(`t(?:elegram)?\.me/([a-zA-Z][a-zA-Z0-9_]{4,31})`)
	m := re.FindStringSubmatch(link)
	if len(m) > 1 {
		return m[1]
	}
	return ""
}