// Package gitea wraps the slice of Gitea's REST API that agents need
// daily: Actions runs, job logs and releases — plus the wait logic
// that encodes the homelab's "serialize heavy builds" rule.
package gitea

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"sort"
	"strings"
	"time"
)

// Task is one Actions job as returned by /actions/tasks. Gitea calls
// these tasks; each run can hold several.
type Task struct {
	ID           int64     `json:"id"`
	Name         string    `json:"name"`
	HeadBranch   string    `json:"head_branch"`
	RunNumber    int64     `json:"run_number"`
	Status       string    `json:"status"`
	DisplayTitle string    `json:"display_title"`
	WorkflowID   string    `json:"workflow_id"`
	URL          string    `json:"url"`
	CreatedAt    time.Time `json:"created_at"`
	UpdatedAt    time.Time `json:"updated_at"`
	RunStartedAt time.Time `json:"run_started_at"`
}

// Active reports whether the task still occupies (or will occupy) the
// runner.
func (t Task) Active() bool {
	switch t.Status {
	case "running", "waiting", "blocked":
		return true
	}
	return false
}

// OK reports whether the task ended well (skipped counts as ok).
func (t Task) OK() bool {
	return t.Status == "success" || t.Status == "skipped"
}

func (t Task) Duration() time.Duration {
	if t.RunStartedAt.IsZero() || t.UpdatedAt.IsZero() || t.Active() {
		return 0
	}
	d := t.UpdatedAt.Sub(t.RunStartedAt)
	if d < 0 {
		return 0
	}
	return d
}

// Release is a Gitea release with its downloadable assets.
type Release struct {
	TagName     string    `json:"tag_name"`
	Name        string    `json:"name"`
	PublishedAt time.Time `json:"published_at"`
	Assets      []struct {
		Name        string `json:"name"`
		Size        int64  `json:"size"`
		DownloadURL string `json:"browser_download_url"`
	} `json:"assets"`
}

type Client struct {
	BaseURL string // e.g. https://gitea.brasse-pc.eu
	Owner   string
	Token   string // optional; required for private repos
	HTTP    *http.Client
}

func New(baseURL, owner, token string) *Client {
	return &Client{
		BaseURL: strings.TrimRight(baseURL, "/"),
		Owner:   owner,
		Token:   token,
		HTTP:    &http.Client{Timeout: 60 * time.Second},
	}
}

func (c *Client) get(path string) (*http.Response, error) {
	req, err := http.NewRequest("GET", c.BaseURL+path, nil)
	if err != nil {
		return nil, err
	}
	if c.Token != "" {
		req.Header.Set("Authorization", "token "+c.Token)
	}
	resp, err := c.HTTP.Do(req)
	if err != nil {
		return nil, err
	}
	if resp.StatusCode == 404 {
		resp.Body.Close()
		return nil, fmt.Errorf("not found (private repo without token in the config?)")
	}
	if resp.StatusCode >= 300 {
		body, _ := io.ReadAll(io.LimitReader(resp.Body, 2048))
		resp.Body.Close()
		return nil, fmt.Errorf("gitea answered %s: %s", resp.Status, strings.TrimSpace(string(body)))
	}
	return resp, nil
}

// Tasks lists a repo's Actions jobs, newest first.
func (c *Client) Tasks(repo string, limit int) ([]Task, error) {
	resp, err := c.get(fmt.Sprintf("/api/v1/repos/%s/%s/actions/tasks?limit=%d",
		url.PathEscape(c.Owner), url.PathEscape(repo), limit))
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	var out struct {
		WorkflowRuns []Task `json:"workflow_runs"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&out); err != nil {
		return nil, err
	}
	sort.Slice(out.WorkflowRuns, func(i, j int) bool {
		return out.WorkflowRuns[i].ID > out.WorkflowRuns[j].ID
	})
	if limit > 0 && len(out.WorkflowRuns) > limit {
		out.WorkflowRuns = out.WorkflowRuns[:limit]
	}
	return out.WorkflowRuns, nil
}

// LogAPI fetches a job log through the token-authenticated API.
func (c *Client) LogAPI(repo string, taskID int64) (string, error) {
	resp, err := c.get(fmt.Sprintf("/api/v1/repos/%s/%s/actions/jobs/%d/logs",
		url.PathEscape(c.Owner), url.PathEscape(repo), taskID))
	if err != nil {
		return "", err
	}
	defer resp.Body.Close()
	data, err := io.ReadAll(io.LimitReader(resp.Body, 64<<20))
	return string(data), err
}

// LogWeb fetches a job log through the web route, which works
// anonymously for public repos (job = index within the run, not id).
func (c *Client) LogWeb(repo string, runNumber int64, jobIndex int) (string, error) {
	resp, err := c.get(fmt.Sprintf("/%s/%s/actions/runs/%d/jobs/%d/logs",
		url.PathEscape(c.Owner), url.PathEscape(repo), runNumber, jobIndex))
	if err != nil {
		return "", err
	}
	defer resp.Body.Close()
	data, err := io.ReadAll(io.LimitReader(resp.Body, 64<<20))
	if err != nil {
		return "", err
	}
	if strings.HasPrefix(strings.TrimSpace(string(data)), "<") {
		return "", fmt.Errorf("got HTML instead of a log (login page? private repo needs a token)")
	}
	return string(data), nil
}

// ZstPath is where Gitea's file storage keeps a task's compressed log
// on the server: <dir>/<owner>/<repo>/<hex(taskID%256)>/<taskID>.log.zst.
// Used by the ssh fallback for logs the HTTP routes no longer serve.
func ZstPath(dir, owner, repo string, taskID int64) string {
	return fmt.Sprintf("%s/%s/%s/%02x/%d.log.zst", dir, owner, repo, taskID%256, taskID)
}

// Releases lists a repo's releases, newest first.
func (c *Client) Releases(repo string, limit int) ([]Release, error) {
	resp, err := c.get(fmt.Sprintf("/api/v1/repos/%s/%s/releases?limit=%d",
		url.PathEscape(c.Owner), url.PathEscape(repo), limit))
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	var out []Release
	if err := json.NewDecoder(resp.Body).Decode(&out); err != nil {
		return nil, err
	}
	return out, nil
}

// --- wait logic (injectable fetch so it is testable) ---

type TaskFetcher func(repo string) ([]Task, error)

type WaitResult struct {
	Done     bool // latest run finished within the timeout
	AllOK    bool
	Tasks    []Task // the latest run's tasks (or last seen)
	Attempts int
}

// WaitRun polls until every task of repo's newest run has finished.
func WaitRun(repo string, fetch TaskFetcher, interval, timeout time.Duration, log func(string)) (WaitResult, error) {
	start := time.Now()
	res := WaitResult{}
	for {
		res.Attempts++
		tasks, err := fetch(repo)
		if err != nil {
			return res, err
		}
		if len(tasks) == 0 {
			return res, fmt.Errorf("repo has no Actions runs")
		}
		latest := tasks[0].RunNumber
		var runTasks []Task
		active := false
		allOK := true
		for _, t := range tasks {
			if t.RunNumber != latest {
				continue
			}
			runTasks = append(runTasks, t)
			if t.Active() {
				active = true
			} else if !t.OK() {
				allOK = false
			}
		}
		res.Tasks = runTasks
		if !active {
			res.Done, res.AllOK = true, allOK
			return res, nil
		}
		if log != nil {
			log(fmt.Sprintf("run #%d still active (%d jobs), waiting...", latest, len(runTasks)))
		}
		if time.Since(start)+interval > timeout {
			return res, nil
		}
		time.Sleep(interval)
	}
}

// CountActive counts active jobs across the given repos.
func CountActive(repos []string, fetch TaskFetcher) (int, []string, error) {
	count := 0
	var busy []string
	for _, r := range repos {
		tasks, err := fetch(r)
		if err != nil {
			return 0, nil, fmt.Errorf("%s: %w", r, err)
		}
		for _, t := range tasks {
			if t.Active() {
				count++
				busy = append(busy, fmt.Sprintf("%s#%d(%s)", r, t.RunNumber, t.Status))
			}
		}
	}
	return count, busy, nil
}

// WaitQuiet blocks until at most maxActive jobs run across repos —
// the "serialize pushes, >2 heavy builds take the Pi5 down" rule.
func WaitQuiet(repos []string, maxActive int, fetch TaskFetcher, interval, timeout time.Duration, log func(string)) (bool, error) {
	start := time.Now()
	for {
		n, busy, err := CountActive(repos, fetch)
		if err != nil {
			return false, err
		}
		if n <= maxActive {
			return true, nil
		}
		if log != nil {
			log(fmt.Sprintf("%d active builds (max %d): %s", n, maxActive, strings.Join(busy, " ")))
		}
		if time.Since(start)+interval > timeout {
			return false, nil
		}
		time.Sleep(interval)
	}
}