/*
Copyright 2026.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package gitea

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

	"github.com/bapung/gitea-runner-operator/api/v1alpha1"
)

// Client defines the interface for interacting with Gitea API
type Client interface {
	// GetRunnerStats queries Gitea for queued workflow runs matching the scope and labels
	GetRunnerStats(
		ctx context.Context,
		giteaURL string,
		authToken string,
		scope v1alpha1.RunnerGroupScope,
		org string,
		user string,
		repo string,
		labels []string,
	) (*RunnerStats, error)
}

// RunnerStats contains lists of jobs in different states
type RunnerStats struct {
	QueuedJobs []ActionWorkflowJob
}

// HTTPClient is the default implementation of the Gitea Client interface
type HTTPClient struct {
	httpClient *http.Client
}

// NewHTTPClient creates a new Gitea HTTP client
func NewHTTPClient() *HTTPClient {
	return &HTTPClient{
		httpClient: &http.Client{
			Timeout: 30 * time.Second,
		},
	}
}

// Repository represents a Gitea repository
type Repository struct {
	Owner struct {
		Login string `json:"login"`
	} `json:"owner"`
	Name     string `json:"name"`
	FullName string `json:"full_name"`
}

// Organization represents a Gitea organization
type Organization struct {
	Username string `json:"username"`
	Name     string `json:"name"`
}

// ActionWorkflowRunsResponse represents the response structure for workflow runs
type ActionWorkflowRunsResponse struct {
	TotalCount   int64               `json:"total_count"`
	WorkflowRuns []ActionWorkflowRun `json:"workflow_runs"`
}

// ActionWorkflowRun represents a Gitea workflow run
type ActionWorkflowRun struct {
	ID           int64  `json:"id"`
	Status       string `json:"status"`
	DisplayTitle string `json:"display_title"`
	Event        string `json:"event"`
	HeadBranch   string `json:"head_branch"`
	HeadSha      string `json:"head_sha"`
	RunNumber    int64  `json:"run_number"`
}

// ActionWorkflowJobsResponse represents the response structure for workflow jobs
type ActionWorkflowJobsResponse struct {
	TotalCount int64               `json:"total_count"`
	Jobs       []ActionWorkflowJob `json:"jobs"`
}

// ActionWorkflowJob represents a Gitea workflow job with runner labels
type ActionWorkflowJob struct {
	ID         int64    `json:"id"`
	Status     string   `json:"status"`
	Name       string   `json:"name"`
	Labels     []string `json:"labels"`
	RunID      int64    `json:"run_id"`
	RunnerID   int64    `json:"runner_id"`
	RunnerName string   `json:"runner_name"`
}

// GetRunnerStats implements the Client interface
func (c *HTTPClient) GetRunnerStats(
	ctx context.Context,
	giteaURL string,
	authToken string,
	scope v1alpha1.RunnerGroupScope,
	org string,
	user string,
	repo string,
	labels []string,
) (*RunnerStats, error) {
	switch scope {
	case v1alpha1.RunnerGroupScopeRepo:
		return c.getRunnerStatsForRepo(ctx, giteaURL, authToken, org, repo, labels)
	case v1alpha1.RunnerGroupScopeOrg:
		return c.getRunnerStatsForOrg(ctx, giteaURL, authToken, org, labels)
	case v1alpha1.RunnerGroupScopeUser:
		return c.getRunnerStatsForUser(ctx, giteaURL, authToken, user, labels)
	case v1alpha1.RunnerGroupScopeGlobal:
		return c.getRunnerStatsGlobal(ctx, giteaURL, authToken, labels)
	default:
		return nil, fmt.Errorf("unknown scope: %s", scope)
	}
}

// getRunnerStatsForRepo fetches queued runs for a specific repository
func (c *HTTPClient) getRunnerStatsForRepo(ctx context.Context, giteaURL, authToken, owner, repo string, labels []string) (*RunnerStats, error) {
	endpoint := fmt.Sprintf("%s/api/v1/repos/%s/%s/actions/jobs", strings.TrimSuffix(giteaURL, "/"), owner, repo)
	return c.fetchRunnerStats(ctx, endpoint, authToken, labels)
}

// getRunnerStatsForOrg fetches queued runs for all repos under an organization
func (c *HTTPClient) getRunnerStatsForOrg(ctx context.Context, giteaURL, authToken, org string, labels []string) (*RunnerStats, error) {
	endpoint := fmt.Sprintf("%s/api/v1/orgs/%s/actions/jobs", strings.TrimSuffix(giteaURL, "/"), org)
	return c.fetchRunnerStats(ctx, endpoint, authToken, labels)
}

// getRunnerStatsForUser fetches queued runs for all repos owned by a user
func (c *HTTPClient) getRunnerStatsForUser(ctx context.Context, giteaURL, authToken, user string, labels []string) (*RunnerStats, error) {
	repos, err := c.fetchReposForUser(ctx, giteaURL, authToken, user)
	if err != nil {
		return nil, err
	}

	var allQueuedJobs []ActionWorkflowJob
	for _, repo := range repos {
		endpoint := fmt.Sprintf("%s/api/v1/repos/%s/%s/actions/jobs", strings.TrimSuffix(giteaURL, "/"), repo.Owner.Login, repo.Name)
		stats, err := c.fetchRunnerStats(ctx, endpoint, authToken, labels)
		if err != nil {
			return nil, err
		}
		allQueuedJobs = append(allQueuedJobs, stats.QueuedJobs...)
	}

	return &RunnerStats{
		QueuedJobs: allQueuedJobs,
	}, nil
}

// getRunnerStatsGlobal fetches queued runs using admin-level API for global scope
func (c *HTTPClient) getRunnerStatsGlobal(ctx context.Context, giteaURL, authToken string, labels []string) (*RunnerStats, error) {
	endpoint := fmt.Sprintf("%s/api/v1/admin/actions/jobs", strings.TrimSuffix(giteaURL, "/"))
	return c.fetchRunnerStats(ctx, endpoint, authToken, labels)
}

func (c *HTTPClient) fetchRunnerStats(ctx context.Context, endpoint, authToken string, labels []string) (*RunnerStats, error) {
	queuedJobs, err := c.fetchWorkflowJobs(ctx, endpoint, authToken, labels, []string{"queued", "waiting", "pending"})
	if err != nil {
		return nil, err
	}

	return &RunnerStats{
		QueuedJobs: queuedJobs,
	}, nil
}

// fetchWorkflowJobs fetches workflow jobs from a given endpoint with label filtering and pagination
func (c *HTTPClient) fetchWorkflowJobs(ctx context.Context, endpoint, authToken string, labels []string, statuses []string) ([]ActionWorkflowJob, error) {
	var allJobs []ActionWorkflowJob

	for _, status := range statuses {
		page := 1
		limit := 50 // Default page size

		for {
			u, err := url.Parse(endpoint)
			if err != nil {
				return nil, err
			}
			q := u.Query()
			q.Set("status", status)
			q.Set("page", fmt.Sprintf("%d", page))
			q.Set("limit", fmt.Sprintf("%d", limit))
			u.RawQuery = q.Encode()

			fmt.Printf("DEBUG: Fetching jobs from %s\n", u.String())

			req, err := http.NewRequestWithContext(ctx, "GET", u.String(), nil)
			if err != nil {
				return nil, err
			}

			req.Header.Set("Authorization", "token "+authToken)
			req.Header.Set("Accept", "application/json")

			resp, err := c.httpClient.Do(req)
			if err != nil {
				fmt.Printf("DEBUG: Request failed: %v\n", err)
				return nil, err
			}

			fmt.Printf("DEBUG: Response status: %s\n", resp.Status)

			if resp.StatusCode != http.StatusOK {
				body, _ := io.ReadAll(resp.Body)
				_ = resp.Body.Close()
				fmt.Printf("DEBUG: Error body: %s\n", string(body))
				return nil, c.handleHTTPError(resp.StatusCode, body, "fetch workflow jobs")
			}

			body, _ := io.ReadAll(resp.Body)
			_ = resp.Body.Close()
			fmt.Printf("DEBUG: Response body: %s\n", string(body))

			var result ActionWorkflowJobsResponse
			if err := json.Unmarshal(body, &result); err != nil {
				fmt.Printf("DEBUG: Failed to decode response: %v\n", err)
				return nil, err
			}

			fmt.Printf("DEBUG: Found %d jobs, total in Gitea: %d\n", len(result.Jobs), result.TotalCount)

			// Filter and collect matching jobs for this page
			matchedJobs := c.filterQueuedJobs(result.Jobs, labels)
			fmt.Printf("DEBUG: %d jobs matched labels %v\n", len(matchedJobs), labels)
			allJobs = append(allJobs, matchedJobs...)

			// Break if we've fetched all available results
			if len(result.Jobs) < limit {
				break
			}

			page++
		}
	}

	return allJobs, nil
}

// fetchReposForUser fetches all repositories owned by a specific user with pagination
func (c *HTTPClient) fetchReposForUser(ctx context.Context, giteaURL, authToken, username string) ([]Repository, error) {
	var allRepos []Repository
	page := 1
	limit := 50

	for {
		endpoint := fmt.Sprintf("%s/api/v1/users/%s/repos", strings.TrimSuffix(giteaURL, "/"), username)
		u, err := url.Parse(endpoint)
		if err != nil {
			return nil, err
		}
		q := u.Query()
		q.Set("page", fmt.Sprintf("%d", page))
		q.Set("limit", fmt.Sprintf("%d", limit))
		u.RawQuery = q.Encode()

		fmt.Printf("DEBUG: Fetching repos for user %s from %s\n", username, u.String())

		req, err := http.NewRequestWithContext(ctx, "GET", u.String(), nil)
		if err != nil {
			return nil, err
		}

		req.Header.Set("Authorization", "token "+authToken)
		req.Header.Set("Accept", "application/json")

		resp, err := c.httpClient.Do(req)
		if err != nil {
			fmt.Printf("DEBUG: Request failed: %v\n", err)
			return nil, err
		}

		fmt.Printf("DEBUG: Response status: %s\n", resp.Status)

		if resp.StatusCode != http.StatusOK {
			body, _ := io.ReadAll(resp.Body)
			_ = resp.Body.Close()
			fmt.Printf("DEBUG: Error body: %s\n", string(body))
			return nil, c.handleHTTPError(resp.StatusCode, body, "fetch user repos")
		}

		body, _ := io.ReadAll(resp.Body)
		_ = resp.Body.Close()
		// fmt.Printf("DEBUG: Response body: %s\n", string(body))

		var repos []Repository
		if err := json.Unmarshal(body, &repos); err != nil {
			fmt.Printf("DEBUG: Failed to decode response: %v\n", err)
			return nil, err
		}

		allRepos = append(allRepos, repos...)

		if len(repos) < limit {
			break
		}

		page++
	}

	return allRepos, nil
}

// filterQueuedJobs filters workflow jobs by labels
func (c *HTTPClient) filterQueuedJobs(jobs []ActionWorkflowJob, runnerLabels []string) []ActionWorkflowJob {
	var matched []ActionWorkflowJob
	for _, job := range jobs {
		match := c.jobMatchesLabels(job.Labels, runnerLabels)
		fmt.Printf("DEBUG: Job %d (Status: %s, Labels: %v) matches runner capabilities %v? %v\n", job.ID, job.Status, job.Labels, runnerLabels, match)
		if match {
			matched = append(matched, job)
		}
	}
	return matched
}

// jobMatchesLabels checks if a job's requirements are satisfied by the runner's supported labels
func (c *HTTPClient) jobMatchesLabels(jobLabels, supportedLabels []string) bool {
	if len(jobLabels) == 0 {
		return true
	}

	// For each label required by the job, check if the runner supports it
	for _, req := range jobLabels {
		found := false
		for _, supp := range supportedLabels {
			// Check for exact match or schema match (label:schema)
			// e.g. Job asks for "ubuntu-latest", Runner has "ubuntu-latest:docker://..."
			if req == supp || strings.HasPrefix(supp, req+":") {
				found = true
				break
			}
		}
		if !found {
			return false
		}
	}
	return true
}

// handleHTTPError provides specific error handling for different HTTP status codes
func (c *HTTPClient) handleHTTPError(statusCode int, body []byte, operation string) error {
	switch statusCode {
	case http.StatusUnauthorized:
		return fmt.Errorf("authentication failed for %s: check your token", operation)
	case http.StatusForbidden:
		return fmt.Errorf("access denied for %s: insufficient permissions", operation)
	case http.StatusNotFound:
		return fmt.Errorf("resource not found for %s: check URL and resource exists", operation)
	case http.StatusTooManyRequests:
		return fmt.Errorf("rate limit exceeded for %s: please retry later", operation)
	case http.StatusInternalServerError:
		return fmt.Errorf("internal server error for %s: %s", operation, string(body))
	default:
		return fmt.Errorf("gitea API returned status %d for %s: %s", statusCode, operation, string(body))
	}
}