Add gitea provider

backend/app/gitprovider/gitea.go

@@ -0,0 +1,141 @@
+package gitprovider
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+type GiteaProvider struct {
+	protocol  string
+	baseUrl   string
+	authToken string
+}
+
+var _ GitProvider = (*GiteaProvider)(nil)
+
+func (p *GiteaProvider) FetchAndDeployBranch(owner, repo, branch, destPath string) (*DeployResult, error) {
+	apiUrl := fmt.Sprintf("%s://%s/api/v1/", p.protocol, strings.TrimSuffix(p.baseUrl, "/"))
+
+	result, err := fetchGiteaBranchHead(apiUrl, owner, repo, branch, p.authToken)
+	if err != nil {
+		return nil, fmt.Errorf("fetching branch head: %w", err)
+	}
+
+	if err = downloadAndExtractGitea(apiUrl, owner, repo, branch, p.authToken, destPath); err != nil {
+		return nil, err
+	}
+
+	return result, nil
+}
+
+func fetchGiteaBranchHead(apiUrl, owner, repo, branch, token string) (*DeployResult, error) {
+	url := fmt.Sprintf("%srepos/%s/%s/branches/%s", apiUrl, owner, repo, branch)
+
+	req, err := http.NewRequest(http.MethodGet, url, nil)
+	if err != nil {
+		return nil, fmt.Errorf("creating request: %w", err)
+	}
+	req.Header.Set("Authorization", "token "+token)
+	req.Header.Set("Accept", "application/json")
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("fetching branch: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("Gitea returned %s for %s", resp.Status, url)
+	}
+
+	// GET /repos/{owner}/{repo}/branches/{branch} returns a Branch object
+	// whose commit field is a PayloadCommit.
+	var payload struct {
+		Commit struct {
+			ID      string `json:"id"`
+			Message string `json:"message"`
+		} `json:"commit"`
+	}
+	if err = json.NewDecoder(resp.Body).Decode(&payload); err != nil {
+		return nil, fmt.Errorf("decoding branch response: %w", err)
+	}
+
+	return &DeployResult{
+		CommitHash:    payload.Commit.ID,
+		CommitMessage: strings.SplitN(payload.Commit.Message, "\n", 2)[0],
+	}, nil
+}
+
+func downloadAndExtractGitea(apiUrl, owner, repo, branch, token, destDir string) error {
+	// GET /repos/{owner}/{repo}/archive/{sha}.zip
+	archiveURL := fmt.Sprintf("%srepos/%s/%s/archive/%s.zip", apiUrl, owner, repo, branch)
+
+	req, err := http.NewRequest(http.MethodGet, archiveURL, nil)
+	if err != nil {
+		return fmt.Errorf("creating request: %w", err)
+	}
+	req.Header.Set("Authorization", "token "+token)
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("fetching archive: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("Gitea returned %s for %s", resp.Status, archiveURL)
+	}
+
+	storageRoot := filepath.Dir(destDir)
+
+	tmpZip, err := os.CreateTemp(storageRoot, "giteabranch-*.zip")
+	if err != nil {
+		return fmt.Errorf("creating temp zip: %w", err)
+	}
+	defer os.Remove(tmpZip.Name())
+
+	if _, err = io.Copy(tmpZip, resp.Body); err != nil {
+		tmpZip.Close()
+		return fmt.Errorf("writing zip: %w", err)
+	}
+	tmpZip.Close()
+
+	tmpDir, err := os.MkdirTemp(storageRoot, "giteabranch-unpack-*")
+	if err != nil {
+		return fmt.Errorf("creating temp dir: %w", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	if err = unzip(tmpZip.Name(), tmpDir); err != nil {
+		return fmt.Errorf("unzipping: %w", err)
+	}
+
+	// Gitea wraps everything in {repo}-{branch}/ (all lowercase).
+	entries, err := os.ReadDir(tmpDir)
+	if err != nil {
+		return fmt.Errorf("reading temp dir: %w", err)
+	}
+	if len(entries) != 1 || !entries[0].IsDir() {
+		return fmt.Errorf("unexpected archive layout: expected a single root directory")
+	}
+	extractedRoot := filepath.Join(tmpDir, entries[0].Name())
+
+	if err = os.MkdirAll(filepath.Dir(destDir), 0o755); err != nil {
+		return fmt.Errorf("creating destination parent dirs: %w", err)
+	}
+	os.RemoveAll(destDir)
+
+	if err = os.Rename(extractedRoot, destDir); err == nil {
+		return nil
+	}
+
+	if err = copyDir(extractedRoot, destDir); err != nil {
+		return fmt.Errorf("cross-device copy to destination: %w", err)
+	}
+	return nil
+}