// Package gitea provides an aggregation layer over the Gitea API,
// supporting concurrent fetching across multiple organizations and repos
// with in-memory caching.
package gitea

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"log/slog"
	"math"
	"net/http"
	"sort"
	"strconv"
	"strings"
	"sync"
	"time"
)

// Client wraps the Gitea API with aggregation and caching capabilities.
type Client struct {
	baseURL    string
	httpClient *http.Client

	mu    sync.RWMutex
	cache map[string]*cacheEntry

	// maxConcurrent controls the semaphore size for parallel API calls.
	maxConcurrent int
	// cacheTTL controls how long cache entries remain valid.
	cacheTTL time.Duration

	// maxRetries is the maximum number of retries for rate-limited requests.
	maxRetries int
	// baseRetryDelay is the initial backoff delay before the first retry.
	baseRetryDelay time.Duration
}

type cacheEntry struct {
	data      interface{}
	expiresAt time.Time
}

// Org represents a Gitea organization.
type Org struct {
	Name        string `json:"username"`
	FullName    string `json:"full_name"`
	Description string `json:"description"`
	AvatarURL   string `json:"avatar_url"`
}

// Repo represents a Gitea repository.
type Repo struct {
	ID          int64  `json:"id"`
	Name        string `json:"name"`
	FullName    string `json:"full_name"`
	Description string `json:"description"`
	Owner       struct {
		Login string `json:"login"`
	} `json:"owner"`
	HTMLURL   string    `json:"html_url"`
	UpdatedAt time.Time `json:"updated_at"`
}

// Issue represents a Gitea issue.
type Issue struct {
	ID     int64  `json:"id"`
	Number int64  `json:"number"`
	Title  string `json:"title"`
	Body   string `json:"body"`
	State  string `json:"state"`
	Labels []struct {
		ID    int64  `json:"id"`
		Name  string `json:"name"`
		Color string `json:"color"`
	} `json:"labels"`
	Assignee *struct {
		Login     string `json:"login"`
		AvatarURL string `json:"avatar_url"`
	} `json:"assignee"`
	Assignees []struct {
		Login     string `json:"login"`
		AvatarURL string `json:"avatar_url"`
	} `json:"assignees"`
	HTMLURL   string    `json:"html_url"`
	CreatedAt time.Time `json:"created_at"`
	UpdatedAt time.Time `json:"updated_at"`
	RepoOwner string    `json:"-"` // populated after fetch
	RepoName  string    `json:"-"` // populated after fetch
}

// PullRequest represents a Gitea pull request.
type PullRequest struct {
	ID     int64  `json:"id"`
	Number int64  `json:"number"`
	Title  string `json:"title"`
	Body   string `json:"body"`
	State  string `json:"state"`
	Labels []struct {
		ID    int64  `json:"id"`
		Name  string `json:"name"`
		Color string `json:"color"`
	} `json:"labels"`
	User *struct {
		Login     string `json:"login"`
		AvatarURL string `json:"avatar_url"`
	} `json:"user"`
	Mergeable bool   `json:"mergeable"`
	HTMLURL   string `json:"html_url"`
	DiffURL   string `json:"diff_url"`
	Additions int    `json:"additions"`
	Deletions int    `json:"deletions"`
	CreatedAt time.Time `json:"created_at"`
	UpdatedAt time.Time `json:"updated_at"`
	RepoOwner   string `json:"-"` // populated after fetch
	RepoName    string `json:"-"` // populated after fetch
	ReviewState string `json:"-"` // aggregated review state: "approved", "changes_requested", "pending", or ""
}

// TriageItem represents an item in the triage queue.
type TriageItem struct {
	Type      string    // "issue" or "pull"
	RepoOwner string
	RepoName  string
	Number    int64
	Title     string
	HTMLURL   string
	Labels    []string
	UpdatedAt time.Time
}

// NewClient creates a new Gitea API client.
func NewClient(baseURL string) *Client {
	return &Client{
		baseURL: strings.TrimRight(baseURL, "/"),
		httpClient: &http.Client{
			Timeout: 30 * time.Second,
		},
		cache:          make(map[string]*cacheEntry),
		maxConcurrent:  5,
		cacheTTL:       30 * time.Second,
		maxRetries:     3,
		baseRetryDelay: 1 * time.Second,
	}
}

// doRequest performs an authenticated HTTP request to the Gitea API.
// It automatically retries on HTTP 429 (rate limit) responses with
// exponential backoff, respecting the Retry-After header when present.
func (c *Client) doRequest(ctx context.Context, token, method, path string, body io.Reader) (*http.Response, error) {
	url := c.baseURL + "/api/v1" + path

	// Read the body once so we can replay it on retries.
	var bodyBytes []byte
	if body != nil {
		var err error
		bodyBytes, err = io.ReadAll(body)
		if err != nil {
			return nil, fmt.Errorf("reading request body: %w", err)
		}
	}

	var lastErr error
	for attempt := 0; attempt <= c.maxRetries; attempt++ {
		// Recreate the body reader for each attempt.
		var reqBody io.Reader
		if bodyBytes != nil {
			reqBody = strings.NewReader(string(bodyBytes))
		}

		req, err := http.NewRequestWithContext(ctx, method, url, reqBody)
		if err != nil {
			return nil, fmt.Errorf("creating request: %w", err)
		}

		req.Header.Set("Authorization", "token "+token)
		req.Header.Set("Accept", "application/json")
		if bodyBytes != nil {
			req.Header.Set("Content-Type", "application/json")
		}

		resp, err := c.httpClient.Do(req)
		if err != nil {
			return nil, fmt.Errorf("executing request: %w", err)
		}

		// Not rate-limited: handle normally.
		if resp.StatusCode != http.StatusTooManyRequests {
			if resp.StatusCode >= 400 {
				defer resp.Body.Close()
				respBody, _ := io.ReadAll(resp.Body)
				return nil, fmt.Errorf("API error %d: %s", resp.StatusCode, string(respBody))
			}
			return resp, nil
		}

		// Rate-limited (429): close body and compute retry delay.
		resp.Body.Close()

		if attempt == c.maxRetries {
			lastErr = fmt.Errorf("API rate limit exceeded after %d retries (429)", c.maxRetries)
			break
		}

		delay := c.retryDelay(resp, attempt)
		slog.Warn("rate limited by Gitea API, retrying",
			"attempt", attempt+1,
			"max_retries", c.maxRetries,
			"delay", delay,
			"path", path,
		)

		select {
		case <-ctx.Done():
			return nil, ctx.Err()
		case <-time.After(delay):
			// Continue to next attempt.
		}
	}

	return nil, lastErr
}

// retryDelay computes the delay before the next retry attempt. It uses the
// Retry-After header value (in seconds) if present, otherwise falls back to
// exponential backoff: baseRetryDelay * 2^attempt.
func (c *Client) retryDelay(resp *http.Response, attempt int) time.Duration {
	if ra := resp.Header.Get("Retry-After"); ra != "" {
		if seconds, err := strconv.Atoi(ra); err == nil && seconds > 0 {
			return time.Duration(seconds) * time.Second
		}
	}
	// Exponential backoff: 1s, 2s, 4s, ...
	return c.baseRetryDelay * time.Duration(math.Pow(2, float64(attempt)))
}

// getFromCache returns cached data if still valid.
func (c *Client) getFromCache(key string) (interface{}, bool) {
	c.mu.RLock()
	defer c.mu.RUnlock()

	entry, ok := c.cache[key]
	if !ok || time.Now().After(entry.expiresAt) {
		return nil, false
	}
	return entry.data, true
}

// setCache stores data in cache with TTL.
func (c *Client) setCache(key string, data interface{}) {
	c.mu.Lock()
	defer c.mu.Unlock()

	c.cache[key] = &cacheEntry{
		data:      data,
		expiresAt: time.Now().Add(c.cacheTTL),
	}
}

// invalidateCache removes entries matching the given prefix.
func (c *Client) invalidateCache(prefix string) {
	c.mu.Lock()
	defer c.mu.Unlock()

	for k := range c.cache {
		if strings.HasPrefix(k, prefix) {
			delete(c.cache, k)
		}
	}
}

// InvalidateAll clears the entire cache (called on write operations).
func (c *Client) InvalidateAll() {
	c.mu.Lock()
	defer c.mu.Unlock()
	c.cache = make(map[string]*cacheEntry)
}

// ListOrgs returns the organizations the authenticated user belongs to.
func (c *Client) ListOrgs(ctx context.Context, token string) ([]Org, error) {
	cacheKey := "orgs"
	if cached, ok := c.getFromCache(cacheKey); ok {
		return cached.([]Org), nil
	}

	resp, err := c.doRequest(ctx, token, http.MethodGet, "/user/orgs?limit=50", nil)
	if err != nil {
		return nil, fmt.Errorf("listing orgs: %w", err)
	}
	defer resp.Body.Close()

	var orgs []Org
	if err := json.NewDecoder(resp.Body).Decode(&orgs); err != nil {
		return nil, fmt.Errorf("decoding orgs: %w", err)
	}

	c.setCache(cacheKey, orgs)
	return orgs, nil
}

// ListOrgRepos returns all repositories for a given organization.
func (c *Client) ListOrgRepos(ctx context.Context, token, org string) ([]Repo, error) {
	cacheKey := fmt.Sprintf("repos-%s", org)
	if cached, ok := c.getFromCache(cacheKey); ok {
		return cached.([]Repo), nil
	}

	var allRepos []Repo
	page := 1
	for {
		path := fmt.Sprintf("/orgs/%s/repos?limit=50&page=%d", org, page)
		resp, err := c.doRequest(ctx, token, http.MethodGet, path, nil)
		if err != nil {
			return nil, fmt.Errorf("listing repos for %s: %w", org, err)
		}

		var repos []Repo
		if err := json.NewDecoder(resp.Body).Decode(&repos); err != nil {
			resp.Body.Close()
			return nil, fmt.Errorf("decoding repos: %w", err)
		}
		resp.Body.Close()

		if len(repos) == 0 {
			break
		}
		allRepos = append(allRepos, repos...)
		if len(repos) < 50 {
			break
		}
		page++
	}

	c.setCache(cacheKey, allRepos)
	return allRepos, nil
}

// ListOrgsAndRepos returns a map of org name to repos for all orgs the user belongs to.
func (c *Client) ListOrgsAndRepos(ctx context.Context, token string) (map[string][]Repo, error) {
	orgs, err := c.ListOrgs(ctx, token)
	if err != nil {
		return nil, err
	}

	result := make(map[string][]Repo)
	var mu sync.Mutex
	sem := make(chan struct{}, c.maxConcurrent)
	var wg sync.WaitGroup
	var firstErr error

	for _, org := range orgs {
		wg.Add(1)
		go func(orgName string) {
			defer wg.Done()
			sem <- struct{}{}
			defer func() { <-sem }()

			repos, err := c.ListOrgRepos(ctx, token, orgName)
			if err != nil {
				mu.Lock()
				if firstErr == nil {
					firstErr = err
				}
				mu.Unlock()
				return
			}

			mu.Lock()
			result[orgName] = repos
			mu.Unlock()
		}(org.Name)
	}

	wg.Wait()

	if firstErr != nil {
		return nil, firstErr
	}
	return result, nil
}

// PageSize is the number of items returned per page for paginated listings.
const PageSize = 20

// PaginatedIssues holds a page of issues along with pagination metadata.
type PaginatedIssues struct {
	Issues  []Issue
	HasMore bool
}

// PaginatedPulls holds a page of pull requests along with pagination metadata.
type PaginatedPulls struct {
	Pulls   []PullRequest
	HasMore bool
}

// ListAllIssues fetches issues across all repos in the given orgs,
// using concurrent requests with a semaphore. Results are paginated.
// The label parameter filters issues by label name (empty string means no filter).
// The repoFilter parameter narrows results to a single repo name (empty means all repos).
func (c *Client) ListAllIssues(ctx context.Context, token string, orgs []string, state string, page int, label string, repoFilter string) (PaginatedIssues, error) {
	if state == "" {
		state = "open"
	}
	if page < 1 {
		page = 1
	}

	cacheKey := fmt.Sprintf("issues-%s-%s-%s-%s", state, strings.Join(orgs, ","), label, repoFilter)
	var allIssues []Issue
	if cached, ok := c.getFromCache(cacheKey); ok {
		allIssues = cached.([]Issue)
	} else {
		// First, collect all repos for the given orgs.
		var allRepos []Repo
		for _, org := range orgs {
			repos, err := c.ListOrgRepos(ctx, token, org)
			if err != nil {
				return PaginatedIssues{}, fmt.Errorf("listing repos for %s: %w", org, err)
			}
			allRepos = append(allRepos, repos...)
		}

		// Filter to a single repo if specified.
		if repoFilter != "" {
			var filtered []Repo
			for _, r := range allRepos {
				if r.Name == repoFilter {
					filtered = append(filtered, r)
				}
			}
			allRepos = filtered
		}

		// Fan out issue fetching across repos.
		var mu sync.Mutex
		sem := make(chan struct{}, c.maxConcurrent)
		var wg sync.WaitGroup
		var firstErr error

		for _, repo := range allRepos {
			wg.Add(1)
			go func(r Repo) {
				defer wg.Done()
				sem <- struct{}{}
				defer func() { <-sem }()

				path := fmt.Sprintf("/repos/%s/issues?state=%s&type=issues&limit=50", r.FullName, state)
				if label != "" {
					path += "&labels=" + label
				}
				resp, err := c.doRequest(ctx, token, http.MethodGet, path, nil)
				if err != nil {
					mu.Lock()
					if firstErr == nil {
						firstErr = fmt.Errorf("fetching issues for %s: %w", r.FullName, err)
					}
					mu.Unlock()
					return
				}
				defer resp.Body.Close()

				var issues []Issue
				if err := json.NewDecoder(resp.Body).Decode(&issues); err != nil {
					mu.Lock()
					if firstErr == nil {
						firstErr = fmt.Errorf("decoding issues for %s: %w", r.FullName, err)
					}
					mu.Unlock()
					return
				}

				// Tag each issue with repo info.
				for i := range issues {
					issues[i].RepoOwner = r.Owner.Login
					issues[i].RepoName = r.Name
				}

				mu.Lock()
				allIssues = append(allIssues, issues...)
				mu.Unlock()
			}(repo)
		}

		wg.Wait()

		if firstErr != nil {
			return PaginatedIssues{}, firstErr
		}

		// Sort by updated time, newest first.
		sort.Slice(allIssues, func(i, j int) bool {
			return allIssues[i].UpdatedAt.After(allIssues[j].UpdatedAt)
		})

		c.setCache(cacheKey, allIssues)
	}

	// Paginate.
	start := (page - 1) * PageSize
	if start >= len(allIssues) {
		return PaginatedIssues{}, nil
	}
	end := start + PageSize
	hasMore := end < len(allIssues)
	if end > len(allIssues) {
		end = len(allIssues)
	}

	return PaginatedIssues{Issues: allIssues[start:end], HasMore: hasMore}, nil
}

// ListAllPullRequests fetches PRs across all repos in the given orgs.
// Results are paginated. The label parameter filters PRs by label name.
// The repoFilter parameter narrows results to a single repo name.
func (c *Client) ListAllPullRequests(ctx context.Context, token string, orgs []string, state string, page int, label string, repoFilter string) (PaginatedPulls, error) {
	if state == "" {
		state = "open"
	}
	if page < 1 {
		page = 1
	}

	cacheKey := fmt.Sprintf("pulls-%s-%s-%s-%s", state, strings.Join(orgs, ","), label, repoFilter)
	var allPRs []PullRequest
	if cached, ok := c.getFromCache(cacheKey); ok {
		allPRs = cached.([]PullRequest)
	} else {
		var allRepos []Repo
		for _, org := range orgs {
			repos, err := c.ListOrgRepos(ctx, token, org)
			if err != nil {
				return PaginatedPulls{}, fmt.Errorf("listing repos for %s: %w", org, err)
			}
			allRepos = append(allRepos, repos...)
		}

		// Filter to a single repo if specified.
		if repoFilter != "" {
			var filtered []Repo
			for _, r := range allRepos {
				if r.Name == repoFilter {
					filtered = append(filtered, r)
				}
			}
			allRepos = filtered
		}

		var mu sync.Mutex
		sem := make(chan struct{}, c.maxConcurrent)
		var wg sync.WaitGroup
		var firstErr error

		for _, repo := range allRepos {
			wg.Add(1)
			go func(r Repo) {
				defer wg.Done()
				sem <- struct{}{}
				defer func() { <-sem }()

				path := fmt.Sprintf("/repos/%s/pulls?state=%s&limit=50", r.FullName, state)
				if label != "" {
					path += "&labels=" + label
				}
				resp, err := c.doRequest(ctx, token, http.MethodGet, path, nil)
				if err != nil {
					mu.Lock()
					if firstErr == nil {
						firstErr = fmt.Errorf("fetching PRs for %s: %w", r.FullName, err)
					}
					mu.Unlock()
					return
				}
				defer resp.Body.Close()

				var prs []PullRequest
				if err := json.NewDecoder(resp.Body).Decode(&prs); err != nil {
					mu.Lock()
					if firstErr == nil {
						firstErr = fmt.Errorf("decoding PRs for %s: %w", r.FullName, err)
					}
					mu.Unlock()
					return
				}

				for i := range prs {
					prs[i].RepoOwner = r.Owner.Login
					prs[i].RepoName = r.Name
				}

				mu.Lock()
				allPRs = append(allPRs, prs...)
				mu.Unlock()
			}(repo)
		}

		wg.Wait()

		if firstErr != nil {
			return PaginatedPulls{}, firstErr
		}

		sort.Slice(allPRs, func(i, j int) bool {
			return allPRs[i].UpdatedAt.After(allPRs[j].UpdatedAt)
		})

		c.setCache(cacheKey, allPRs)
	}

	// Paginate.
	start := (page - 1) * PageSize
	if start >= len(allPRs) {
		return PaginatedPulls{}, nil
	}
	end := start + PageSize
	hasMore := end < len(allPRs)
	if end > len(allPRs) {
		end = len(allPRs)
	}

	return PaginatedPulls{Pulls: allPRs[start:end], HasMore: hasMore}, nil
}

// GetTriageQueue returns unassigned issues and PRs needing review, sorted by priority.
func (c *Client) GetTriageQueue(ctx context.Context, token string, orgs []string) ([]TriageItem, error) {
	// Collect all open issues across all pages.
	var issues []Issue
	for page := 1; ; page++ {
		result, err := c.ListAllIssues(ctx, token, orgs, "open", page, "", "")
		if err != nil {
			return nil, fmt.Errorf("fetching issues for triage: %w", err)
		}
		issues = append(issues, result.Issues...)
		if !result.HasMore {
			break
		}
	}

	// Collect all open PRs across all pages.
	var prs []PullRequest
	for page := 1; ; page++ {
		result, err := c.ListAllPullRequests(ctx, token, orgs, "open", page, "", "")
		if err != nil {
			return nil, fmt.Errorf("fetching PRs for triage: %w", err)
		}
		prs = append(prs, result.Pulls...)
		if !result.HasMore {
			break
		}
	}

	var queue []TriageItem

	// Add unassigned issues.
	for _, issue := range issues {
		if issue.Assignee == nil && len(issue.Assignees) == 0 {
			var labels []string
			for _, l := range issue.Labels {
				labels = append(labels, l.Name)
			}
			queue = append(queue, TriageItem{
				Type:      "issue",
				RepoOwner: issue.RepoOwner,
				RepoName:  issue.RepoName,
				Number:    issue.Number,
				Title:     issue.Title,
				HTMLURL:   issue.HTMLURL,
				Labels:    labels,
				UpdatedAt: issue.UpdatedAt,
			})
		}
	}

	// Add PRs (all open PRs may need review attention).
	for _, pr := range prs {
		var labels []string
		for _, l := range pr.Labels {
			labels = append(labels, l.Name)
		}
		queue = append(queue, TriageItem{
			Type:      "pull",
			RepoOwner: pr.RepoOwner,
			RepoName:  pr.RepoName,
			Number:    pr.Number,
			Title:     pr.Title,
			HTMLURL:   pr.HTMLURL,
			Labels:    labels,
			UpdatedAt: pr.UpdatedAt,
		})
	}

	// Sort by priority labels (P1 > P2 > P3 > no priority), then by updated time.
	sort.Slice(queue, func(i, j int) bool {
		pi := priorityScore(queue[i].Labels)
		pj := priorityScore(queue[j].Labels)
		if pi != pj {
			return pi < pj // lower score = higher priority
		}
		return queue[i].UpdatedAt.After(queue[j].UpdatedAt)
	})

	return queue, nil
}

// Comment represents a comment on an issue or pull request.
type Comment struct {
	ID        int64  `json:"id"`
	Body      string `json:"body"`
	User      string `json:"-"` // populated from nested object
	CreatedAt string `json:"-"` // formatted after fetch
	RawUser   struct {
		Login string `json:"login"`
	} `json:"user"`
	RawCreatedAt time.Time `json:"created_at"`
}

// Label represents a Gitea label (used for available labels list).
type Label struct {
	ID    int64  `json:"id"`
	Name  string `json:"name"`
	Color string `json:"color"`
}

// GetIssue fetches a single issue by owner, repo, and index.
func (c *Client) GetIssue(ctx context.Context, token, owner, repo string, index int64) (*Issue, error) {
	path := fmt.Sprintf("/repos/%s/%s/issues/%d", owner, repo, index)
	resp, err := c.doRequest(ctx, token, http.MethodGet, path, nil)
	if err != nil {
		return nil, fmt.Errorf("fetching issue: %w", err)
	}
	defer resp.Body.Close()

	var issue Issue
	if err := json.NewDecoder(resp.Body).Decode(&issue); err != nil {
		return nil, fmt.Errorf("decoding issue: %w", err)
	}

	issue.RepoOwner = owner
	issue.RepoName = repo
	return &issue, nil
}

// GetPull fetches a single pull request by owner, repo, and index.
func (c *Client) GetPull(ctx context.Context, token, owner, repo string, index int64) (*PullRequest, error) {
	path := fmt.Sprintf("/repos/%s/%s/pulls/%d", owner, repo, index)
	resp, err := c.doRequest(ctx, token, http.MethodGet, path, nil)
	if err != nil {
		return nil, fmt.Errorf("fetching pull request: %w", err)
	}
	defer resp.Body.Close()

	var pr PullRequest
	if err := json.NewDecoder(resp.Body).Decode(&pr); err != nil {
		return nil, fmt.Errorf("decoding pull request: %w", err)
	}

	pr.RepoOwner = owner
	pr.RepoName = repo
	return &pr, nil
}

// ChangedFile represents a file changed in a pull request.
type ChangedFile struct {
	Filename    string `json:"filename"`
	Status      string `json:"status"` // "added", "modified", "removed", "renamed"
	Additions   int    `json:"additions"`
	Deletions   int    `json:"deletions"`
	Changes     int    `json:"changes"`
	PreviousFilename string `json:"previous_filename,omitempty"`
}

// GetChangedFiles fetches the list of files changed in a pull request.
func (c *Client) GetChangedFiles(ctx context.Context, token, owner, repo string, index int64) ([]ChangedFile, error) {
	path := fmt.Sprintf("/repos/%s/%s/pulls/%d/files?limit=50", owner, repo, index)
	resp, err := c.doRequest(ctx, token, http.MethodGet, path, nil)
	if err != nil {
		return nil, fmt.Errorf("fetching changed files: %w", err)
	}
	defer resp.Body.Close()

	var files []ChangedFile
	if err := json.NewDecoder(resp.Body).Decode(&files); err != nil {
		return nil, fmt.Errorf("decoding changed files: %w", err)
	}

	return files, nil
}

// GetIssueComments fetches comments for an issue or pull request.
func (c *Client) GetIssueComments(ctx context.Context, token, owner, repo string, index int64) ([]Comment, error) {
	path := fmt.Sprintf("/repos/%s/%s/issues/%d/comments?limit=50", owner, repo, index)
	resp, err := c.doRequest(ctx, token, http.MethodGet, path, nil)
	if err != nil {
		return nil, fmt.Errorf("fetching comments: %w", err)
	}
	defer resp.Body.Close()

	var comments []Comment
	if err := json.NewDecoder(resp.Body).Decode(&comments); err != nil {
		return nil, fmt.Errorf("decoding comments: %w", err)
	}

	// Populate convenience fields.
	for i := range comments {
		comments[i].User = comments[i].RawUser.Login
		comments[i].CreatedAt = comments[i].RawCreatedAt.Format("Jan 2, 2006 15:04")
	}

	return comments, nil
}

// GetRepoLabels fetches all labels for a repository.
func (c *Client) GetRepoLabels(ctx context.Context, token, owner, repo string) ([]Label, error) {
	path := fmt.Sprintf("/repos/%s/%s/labels?limit=50", owner, repo)
	resp, err := c.doRequest(ctx, token, http.MethodGet, path, nil)
	if err != nil {
		return nil, fmt.Errorf("fetching labels: %w", err)
	}
	defer resp.Body.Close()

	var labels []Label
	if err := json.NewDecoder(resp.Body).Decode(&labels); err != nil {
		return nil, fmt.Errorf("decoding labels: %w", err)
	}

	return labels, nil
}

// CreateIssue creates a new issue in the specified repository.
func (c *Client) CreateIssue(ctx context.Context, token, owner, repo, title, body string, labels []int64) (*Issue, error) {
	payload := map[string]interface{}{
		"title": title,
		"body":  body,
	}
	if len(labels) > 0 {
		payload["labels"] = labels
	}

	jsonData, err := json.Marshal(payload)
	if err != nil {
		return nil, fmt.Errorf("marshaling issue: %w", err)
	}

	path := fmt.Sprintf("/repos/%s/%s/issues", owner, repo)
	resp, err := c.doRequest(ctx, token, http.MethodPost, path, strings.NewReader(string(jsonData)))
	if err != nil {
		return nil, fmt.Errorf("creating issue: %w", err)
	}
	defer resp.Body.Close()

	var issue Issue
	if err := json.NewDecoder(resp.Body).Decode(&issue); err != nil {
		return nil, fmt.Errorf("decoding created issue: %w", err)
	}

	issue.RepoOwner = owner
	issue.RepoName = repo

	c.InvalidateAll() // Invalidate cache after write.
	return &issue, nil
}

// ApplyLabel adds a label to an issue.
func (c *Client) ApplyLabel(ctx context.Context, token, owner, repo string, index int64, labelIDs []int64) error {
	payload := map[string]interface{}{
		"labels": labelIDs,
	}

	jsonData, err := json.Marshal(payload)
	if err != nil {
		return fmt.Errorf("marshaling labels: %w", err)
	}

	path := fmt.Sprintf("/repos/%s/%s/issues/%d/labels", owner, repo, index)
	resp, err := c.doRequest(ctx, token, http.MethodPost, path, strings.NewReader(string(jsonData)))
	if err != nil {
		return fmt.Errorf("applying labels: %w", err)
	}
	resp.Body.Close()

	c.InvalidateAll()
	return nil
}

// ListCollaborators fetches the list of collaborators (users with access) for a repo.
func (c *Client) ListCollaborators(ctx context.Context, token, owner, repo string) ([]string, error) {
	path := fmt.Sprintf("/repos/%s/%s/collaborators?limit=50", owner, repo)
	resp, err := c.doRequest(ctx, token, http.MethodGet, path, nil)
	if err != nil {
		return nil, fmt.Errorf("fetching collaborators: %w", err)
	}
	defer resp.Body.Close()

	var users []struct {
		Login string `json:"login"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&users); err != nil {
		return nil, fmt.Errorf("decoding collaborators: %w", err)
	}

	var logins []string
	for _, u := range users {
		logins = append(logins, u.Login)
	}
	return logins, nil
}

// AssignIssue sets the assignees on an issue.
func (c *Client) AssignIssue(ctx context.Context, token, owner, repo string, index int64, assignees []string) error {
	payload, err := json.Marshal(map[string]interface{}{
		"assignees": assignees,
	})
	if err != nil {
		return fmt.Errorf("marshaling assignees: %w", err)
	}

	path := fmt.Sprintf("/repos/%s/%s/issues/%d", owner, repo, index)
	resp, err := c.doRequest(ctx, token, http.MethodPatch, path, strings.NewReader(string(payload)))
	if err != nil {
		return fmt.Errorf("assigning issue: %w", err)
	}
	resp.Body.Close()

	c.InvalidateAll()
	return nil
}

// SubmitReview submits a review on a pull request.
func (c *Client) SubmitReview(ctx context.Context, token, owner, repo string, index int64, reviewType, body string) error {
	payload := map[string]interface{}{
		"event": reviewType, // "APPROVED", "REQUEST_CHANGES", "COMMENT"
		"body":  body,
	}

	jsonData, err := json.Marshal(payload)
	if err != nil {
		return fmt.Errorf("marshaling review: %w", err)
	}

	path := fmt.Sprintf("/repos/%s/%s/pulls/%d/reviews", owner, repo, index)
	resp, err := c.doRequest(ctx, token, http.MethodPost, path, strings.NewReader(string(jsonData)))
	if err != nil {
		return fmt.Errorf("submitting review: %w", err)
	}
	resp.Body.Close()

	c.InvalidateAll()
	return nil
}

// CloseIssue closes an issue by setting its state to "closed".
func (c *Client) CloseIssue(ctx context.Context, token, owner, repo string, index int64) error {
	return c.SetIssueState(ctx, token, owner, repo, index, "closed")
}

// SetIssueState sets an issue's state (e.g. "open" or "closed").
func (c *Client) SetIssueState(ctx context.Context, token, owner, repo string, index int64, state string) error {
	payload, err := json.Marshal(map[string]string{"state": state})
	if err != nil {
		return fmt.Errorf("marshaling state change: %w", err)
	}

	path := fmt.Sprintf("/repos/%s/%s/issues/%d", owner, repo, index)
	resp, err := c.doRequest(ctx, token, http.MethodPatch, path, strings.NewReader(string(payload)))
	if err != nil {
		return fmt.Errorf("setting issue state: %w", err)
	}
	resp.Body.Close()

	c.InvalidateAll()
	return nil
}

// MergePull merges a pull request using the specified merge style.
// Valid styles: "merge", "rebase", "rebase-merge", "squash".
// If style is empty, defaults to "merge".
func (c *Client) MergePull(ctx context.Context, token, owner, repo string, index int64, style, title, message string) error {
	if style == "" {
		style = "merge"
	}

	payload := map[string]string{
		"Do": style,
	}
	if title != "" {
		payload["merge_message_field"] = title
	}
	if message != "" {
		payload["merge_message_field"] = message
	}

	jsonData, err := json.Marshal(payload)
	if err != nil {
		return fmt.Errorf("marshaling merge request: %w", err)
	}

	path := fmt.Sprintf("/repos/%s/%s/pulls/%d/merge", owner, repo, index)
	resp, err := c.doRequest(ctx, token, http.MethodPost, path, strings.NewReader(string(jsonData)))
	if err != nil {
		return fmt.Errorf("merging pull request: %w", err)
	}
	resp.Body.Close()

	c.InvalidateAll()
	return nil
}

// AddComment creates a comment on an issue and returns the created Comment.
func (c *Client) AddComment(ctx context.Context, token, owner, repo string, index int64, body string) (*Comment, error) {
	return c.PostComment(ctx, token, owner, repo, index, body)
}

// PostComment creates a comment on an issue and returns the created Comment.
func (c *Client) PostComment(ctx context.Context, token, owner, repo string, index int64, body string) (*Comment, error) {
	payload, err := json.Marshal(map[string]string{"body": body})
	if err != nil {
		return nil, fmt.Errorf("marshaling comment: %w", err)
	}

	path := fmt.Sprintf("/repos/%s/%s/issues/%d/comments", owner, repo, index)
	resp, err := c.doRequest(ctx, token, http.MethodPost, path, strings.NewReader(string(payload)))
	if err != nil {
		return nil, fmt.Errorf("posting comment: %w", err)
	}
	defer resp.Body.Close()

	var comment Comment
	if err := json.NewDecoder(resp.Body).Decode(&comment); err != nil {
		return nil, fmt.Errorf("decoding comment: %w", err)
	}

	// Populate convenience fields.
	comment.User = comment.RawUser.Login
	comment.CreatedAt = comment.RawCreatedAt.Format("Jan 2, 2006 15:04")

	c.InvalidateAll()
	return &comment, nil
}

// RenderMarkdown renders raw markdown text to HTML using the Gitea API.
// Falls back to the raw text if the API call fails.
func (c *Client) RenderMarkdown(ctx context.Context, token, text string) (string, error) {
	payload, err := json.Marshal(map[string]string{
		"Text": text,
		"Mode": "gfm",
	})
	if err != nil {
		return text, fmt.Errorf("marshaling markdown request: %w", err)
	}

	url := c.baseURL + "/api/v1/markdown"
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, strings.NewReader(string(payload)))
	if err != nil {
		return text, fmt.Errorf("creating markdown request: %w", err)
	}

	req.Header.Set("Authorization", "token "+token)
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Accept", "text/html")

	resp, err := c.httpClient.Do(req)
	if err != nil {
		return text, fmt.Errorf("executing markdown request: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode >= 400 {
		return text, fmt.Errorf("markdown API error %d", resp.StatusCode)
	}

	rendered, err := io.ReadAll(resp.Body)
	if err != nil {
		return text, fmt.Errorf("reading markdown response: %w", err)
	}

	return string(rendered), nil
}

// Review represents a single review on a pull request.
type Review struct {
	ID   int64  `json:"id"`
	Body string `json:"body"`
	State string `json:"state"` // "APPROVED", "REQUEST_CHANGES", "COMMENT", "PENDING"
	User  struct {
		Login string `json:"login"`
	} `json:"user"`
}

// GetPullReviewState fetches reviews for a PR and returns the aggregate state.
// Priority: changes_requested > approved > pending > "" (no reviews).
func (c *Client) GetPullReviewState(ctx context.Context, token, owner, repo string, index int64) string {
	path := fmt.Sprintf("/repos/%s/%s/pulls/%d/reviews?limit=50", owner, repo, index)
	resp, err := c.doRequest(ctx, token, http.MethodGet, path, nil)
	if err != nil {
		return ""
	}
	defer resp.Body.Close()

	var reviews []Review
	if err := json.NewDecoder(resp.Body).Decode(&reviews); err != nil {
		return ""
	}

	if len(reviews) == 0 {
		return ""
	}

	// Aggregate: last non-comment review per user wins, then pick the "worst" state.
	userState := make(map[string]string)
	for _, r := range reviews {
		switch r.State {
		case "APPROVED", "REQUEST_CHANGES":
			userState[r.User.Login] = r.State
		}
	}

	if len(userState) == 0 {
		return "pending"
	}

	for _, s := range userState {
		if s == "REQUEST_CHANGES" {
			return "changes_requested"
		}
	}
	return "approved"
}

// EnrichPullsWithReviewState fetches review state for each PR concurrently.
func (c *Client) EnrichPullsWithReviewState(ctx context.Context, token string, pulls []PullRequest) {
	sem := make(chan struct{}, c.maxConcurrent)
	var wg sync.WaitGroup

	for i := range pulls {
		wg.Add(1)
		go func(idx int) {
			defer wg.Done()
			sem <- struct{}{}
			defer func() { <-sem }()

			pulls[idx].ReviewState = c.GetPullReviewState(ctx, token, pulls[idx].RepoOwner, pulls[idx].RepoName, pulls[idx].Number)
		}(i)
	}
	wg.Wait()
}

// priorityScore returns a numeric score for sorting (lower = higher priority).
func priorityScore(labels []string) int {
	for _, l := range labels {
		switch l {
		case "P1":
			return 1
		case "P2":
			return 2
		case "P3":
			return 3
		}
	}
	return 4 // no priority label
}