// cmd/xcheck 是 #7 的交叉驗證工具（不屬於 teai 本體，PR 內附驗證說明）。
//
// 以真實 Gitea API 資料源實作 workflow.Source，跑 Go 版 ScanStalled，
// 再與 gitea.py stalled（行為基準）的 JSON 輸出逐欄位比對。
// 建立限制：與 teai 本體一致，僅標準庫。
package main

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"os"
	"strings"
	"time"

	"gitea.alterminal.com/alterminal/teai/internal/workflow"
)

// apiSource 以 Gitea API 實作 workflow.Source。
type apiSource struct {
	base  string
	token string
	hc    *http.Client
}

func (s *apiSource) get(path string, params map[string]string) ([]byte, int, error) {
	u := s.base + path
	if len(params) > 0 {
		q := url.Values{}
		for k, v := range params {
			q.Set(k, v)
		}
		u += "?" + q.Encode()
	}
	req, err := http.NewRequest("GET", u, nil)
	if err != nil {
		return nil, 0, err
	}
	req.Header.Set("Accept", "application/json")
	req.Header.Set("Authorization", "token "+s.token)
	resp, err := s.hc.Do(req)
	if err != nil {
		return nil, 0, err
	}
	defer resp.Body.Close()
	body, err := io.ReadAll(resp.Body)
	return body, resp.StatusCode, err
}

func (s *apiSource) getJSON(path string, params map[string]string, out any) error {
	body, code, err := s.get(path, params)
	if err != nil {
		return err
	}
	if code != 200 {
		return fmt.Errorf("GET %s: HTTP %d", path, code)
	}
	return json.Unmarshal(body, out)
}

// listAll 分頁拉取清單類 API（Gitea 上限 50/頁）。
func (s *apiSource) listAll(path string, params map[string]string, out any) error {
	var items []json.RawMessage
	page := 1
	for {
		q := map[string]string{"page": fmt.Sprint(page), "limit": "50"}
		for k, v := range params {
			q[k] = v
		}
		var chunk json.RawMessage
		if err := s.getJSON(path, q, &chunk); err != nil {
			return err
		}
		var arr []json.RawMessage
		if err := json.Unmarshal(chunk, &arr); err != nil {
			return fmt.Errorf("GET %s: 回傳非陣列", path)
		}
		items = append(items, arr...)
		if len(arr) < 50 {
			break
		}
		page++
	}
	var b strings.Builder
	b.WriteByte('[')
	for i, item := range items {
		if i > 0 {
			b.WriteByte(',')
		}
		b.Write(item)
	}
	b.WriteByte(']')
	return json.Unmarshal([]byte(b.String()), out)
}

// CurrentUser 以 token 呼叫 /user 取實際帳號，與 gitea.py 的
// get_current_username() 同源（token 決定帳號，不接受環境變數覆寫，
// 失敗即報錯退出，不靜默退回預設值）。
func (s *apiSource) CurrentUser() (string, error) {
	var user struct {
		Username string `json:"username"`
		Login    string `json:"login"`
	}
	if err := s.getJSON("user", nil, &user); err != nil {
		return "", err
	}
	if user.Username != "" {
		return user.Username, nil
	}
	if user.Login != "" {
		return user.Login, nil
	}
	return "", fmt.Errorf("無法從 Gitea API /user 取得目前帳號")
}

func (s *apiSource) MyOrganizations() ([]string, error) {
	var orgs []struct {
		Username string `json:"username"`
	}
	if err := s.listAll("user/orgs", nil, &orgs); err != nil {
		return nil, err
	}
	names := make([]string, 0, len(orgs))
	for _, o := range orgs {
		if o.Username != "" {
			names = append(names, o.Username)
		}
	}
	return names, nil
}

func (s *apiSource) OrganizationRepositories(org string) ([]workflow.Repo, error) {
	var repos []workflow.Repo
	if err := s.listAll("orgs/"+org+"/repos", nil, &repos); err != nil {
		return nil, err
	}
	return repos, nil
}

func (s *apiSource) OpenIssues(owner, repo string) ([]workflow.Issue, error) {
	var issues []workflow.Issue
	// 與 gitea.py 一致：type=issues 排除 PR；state=open。
	if err := s.listAll(fmt.Sprintf("repos/%s/%s/issues", owner, repo), map[string]string{"type": "issues", "state": "open"}, &issues); err != nil {
		return nil, err
	}
	return issues, nil
}

func (s *apiSource) OpenPulls(owner, repo string) ([]workflow.PullRequest, error) {
	var pulls []workflow.PullRequest
	if err := s.listAll(fmt.Sprintf("repos/%s/%s/pulls", owner, repo), map[string]string{"state": "open"}, &pulls); err != nil {
		return nil, err
	}
	return pulls, nil
}

func (s *apiSource) IssueComments(owner, repo string, number int64) ([]workflow.Comment, error) {
	var comments []workflow.Comment
	if err := s.listAll(fmt.Sprintf("repos/%s/%s/issues/%d/comments", owner, repo, number), nil, &comments); err != nil {
		return nil, err
	}
	return comments, nil
}

func (s *apiSource) IssueTimeline(owner, repo string, number int64) ([]workflow.TimelineEvent, error) {
	var events []workflow.TimelineEvent
	if err := s.listAll(fmt.Sprintf("repos/%s/%s/issues/%d/timeline", owner, repo, number), nil, &events); err != nil {
		return nil, err
	}
	return events, nil
}

func (s *apiSource) TryGetIssue(owner, repo string, number int64) (workflow.Issue, bool, error) {
	var issue workflow.Issue
	body, code, err := s.get(fmt.Sprintf("repos/%s/%s/issues/%d", owner, repo, number), nil)
	if err != nil {
		return workflow.Issue{}, false, nil
	}
	if code != 200 {
		return workflow.Issue{}, false, nil
	}
	if err := json.Unmarshal(body, &issue); err != nil {
		return workflow.Issue{}, false, nil
	}
	return issue, true, nil
}

// loadEnv 讀 agents 倉庫的 .env（ACCESS_TOKEN、GITEA_API_DOMAIN）。
func loadEnv(path string) {
	data, err := os.ReadFile(path)
	if err != nil {
		return
	}
	for _, line := range strings.Split(string(data), "\n") {
		line = strings.TrimSpace(line)
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}
		k, v, ok := strings.Cut(line, "=")
		if !ok {
			continue
		}
		k = strings.TrimSpace(k)
		v = strings.Trim(strings.TrimSpace(v), "'\"")
		if os.Getenv(k) == "" {
			os.Setenv(k, v)
		}
	}
}

func main() {
	// --xrefs 模式：從 stdin 讀文字，輸出解析後的引用目標（與 gitea.py
	// _resolve_xref_targets 對照用）。組織與倉庫清單來自真實 API。
	if len(os.Args) > 1 && os.Args[1] == "--xrefs" {
		xrefsMain()
		return
	}
	loadEnv(os.Getenv("HOME") + "/agents/.env")
	domain := os.Getenv("GITEA_API_DOMAIN")
	token := os.Getenv("ACCESS_TOKEN")
	if domain == "" || token == "" {
		fmt.Fprintln(os.Stderr, "缺少 GITEA_API_DOMAIN／ACCESS_TOKEN")
		os.Exit(1)
	}
	src := &apiSource{
		base:  "https://" + domain + "/api/v1/",
		token: token,
		hc:    &http.Client{Timeout: 30 * time.Second},
	}
	username, err := src.CurrentUser()
	if err != nil {
		fmt.Fprintln(os.Stderr, "CurrentUser:", err)
		os.Exit(1)
	}
	hours := 4.0
	items, scanErr := workflow.ScanStalled(src, username, hours, time.Now())
	if scanErr != nil {
		fmt.Fprintln(os.Stderr, "ScanStalled:", scanErr)
		os.Exit(1)
	}
	// json.Marshal* 會把 <、>、& 轉義成 \u003c 等（含自訂 MarshalJSON 的輸出），
	// 與 gitea.py（ensure_ascii=False）位元組不相容；必須停用 HTML 轉義。
	var buf bytes.Buffer
	enc := json.NewEncoder(&buf)
	enc.SetEscapeHTML(false)
	enc.SetIndent("", "  ")
	if err := enc.Encode(items); err != nil {
		fmt.Fprintln(os.Stderr, "Encode:", err)
		os.Exit(1)
	}
	fmt.Print(buf.String())
}

// xrefsMain 對 stdin 的每行文字解析引用目標並輸出 JSON。
func xrefsMain() {
	loadEnv(os.Getenv("HOME") + "/agents/.env")
	domain := os.Getenv("GITEA_API_DOMAIN")
	token := os.Getenv("ACCESS_TOKEN")
	if domain == "" || token == "" {
		fmt.Fprintln(os.Stderr, "缺少 GITEA_API_DOMAIN／ACCESS_TOKEN")
		os.Exit(1)
	}
	src := &apiSource{
		base:  "https://" + domain + "/api/v1/",
		token: token,
		hc:    &http.Client{Timeout: 30 * time.Second},
	}
	orgs, err := src.MyOrganizations()
	if err != nil {
		fmt.Fprintln(os.Stderr, "MyOrganizations:", err)
		os.Exit(1)
	}
	myOrgs := map[string]bool{}
	for _, o := range orgs {
		myOrgs[o] = true
	}
	data, _ := io.ReadAll(os.Stdin)
	repos, _ := src.OrganizationRepositories("alterminal")
	names := make([]string, 0, len(repos))
	for _, r := range repos {
		names = append(names, r.Name)
	}
	targets, err := workflow.ResolveXrefTargets("alterminal", "agents", []string{string(data)}, myOrgs, func(string) ([]string, error) {
		return names, nil
	})
	if err != nil {
		fmt.Fprintln(os.Stderr, "ResolveXrefTargets:", err)
		os.Exit(1)
	}
	var buf bytes.Buffer
	enc := json.NewEncoder(&buf)
	enc.SetEscapeHTML(false)
	enc.SetIndent("", "  ")
	if err := enc.Encode(targets); err != nil {
		fmt.Fprintln(os.Stderr, "Encode:", err)
		os.Exit(1)
	}
	fmt.Print(buf.String())
}