added support for get_pull_request_diff (#119)

This function call is needed to be able to do AI code review to actually get the diff from the PR.

Reviewed-on: https://gitea.com/gitea/gitea-mcp/pulls/119
Reviewed-by: silverwind <silverwind@noreply.gitea.com>
Reviewed-by: hiifong <f@f.style>
Co-authored-by: Gustav <tvarsis@hotmail.com>
Co-committed-by: Gustav <tvarsis@hotmail.com>

operation/pull/pull.go

@@ -18,6 +18,7 @@ var Tool = tool.New()
 
 const (
 	GetPullRequestByIndexToolName         = "get_pull_request_by_index"
+	GetPullRequestDiffToolName            = "get_pull_request_diff"
 	ListRepoPullRequestsToolName          = "list_repo_pull_requests"
 	CreatePullRequestToolName             = "create_pull_request"
 	CreatePullRequestReviewerToolName     = "create_pull_request_reviewer"
@@ -40,6 +41,15 @@ var (
 		mcp.WithNumber("index", mcp.Required(), mcp.Description("repository pull request index")),
 	)
 
+	GetPullRequestDiffTool = mcp.NewTool(
+		GetPullRequestDiffToolName,
+		mcp.WithDescription("get pull request diff"),
+		mcp.WithString("owner", mcp.Required(), mcp.Description("repository owner")),
+		mcp.WithString("repo", mcp.Required(), mcp.Description("repository name")),
+		mcp.WithNumber("index", mcp.Required(), mcp.Description("repository pull request index")),
+		mcp.WithBoolean("binary", mcp.Description("whether to include binary file changes")),
+	)
+
 	ListRepoPullRequestsTool = mcp.NewTool(
 		ListRepoPullRequestsToolName,
 		mcp.WithDescription("List repository pull requests"),
@@ -167,6 +177,10 @@ func init() {
 		Tool:    GetPullRequestByIndexTool,
 		Handler: GetPullRequestByIndexFn,
 	})
+	Tool.RegisterRead(server.ServerTool{
+		Tool:    GetPullRequestDiffTool,
+		Handler: GetPullRequestDiffFn,
+	})
 	Tool.RegisterRead(server.ServerTool{
 		Tool:    ListRepoPullRequestsTool,
 		Handler: ListRepoPullRequestsFn,
@@ -239,6 +253,43 @@ func GetPullRequestByIndexFn(ctx context.Context, req mcp.CallToolRequest) (*mcp
 	return to.TextResult(pr)
 }
 
+func GetPullRequestDiffFn(ctx context.Context, req mcp.CallToolRequest) (*mcp.CallToolResult, error) {
+	log.Debugf("Called GetPullRequestDiffFn")
+	owner, ok := req.GetArguments()["owner"].(string)
+	if !ok {
+		return to.ErrorResult(fmt.Errorf("owner is required"))
+	}
+	repo, ok := req.GetArguments()["repo"].(string)
+	if !ok {
+		return to.ErrorResult(fmt.Errorf("repo is required"))
+	}
+	index, ok := req.GetArguments()["index"].(float64)
+	if !ok {
+		return to.ErrorResult(fmt.Errorf("index is required"))
+	}
+	binary, _ := req.GetArguments()["binary"].(bool)
+
+	client, err := gitea.ClientFromContext(ctx)
+	if err != nil {
+		return to.ErrorResult(fmt.Errorf("get gitea client err: %v", err))
+	}
+	diffBytes, _, err := client.GetPullRequestDiff(owner, repo, int64(index), gitea_sdk.PullRequestDiffOptions{
+		Binary: binary,
+	})
+	if err != nil {
+		return to.ErrorResult(fmt.Errorf("get %v/%v/pr/%v diff err: %v", owner, repo, int64(index), err))
+	}
+
+	result := map[string]interface{}{
+		"diff":   string(diffBytes),
+		"binary": binary,
+		"index":  int64(index),
+		"repo":   repo,
+		"owner":  owner,
+	}
+	return to.TextResult(result)
+}
+
 func ListRepoPullRequestsFn(ctx context.Context, req mcp.CallToolRequest) (*mcp.CallToolResult, error) {
 	log.Debugf("Called ListRepoPullRequests")
 	owner, ok := req.GetArguments()["owner"].(string)

operation/pull/pull_test.go

@@ -0,0 +1,140 @@
+package pull
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"sync"
+	"testing"
+
+	"gitea.com/gitea/gitea-mcp/pkg/flag"
+	"github.com/mark3labs/mcp-go/mcp"
+)
+
+func TestGetPullRequestDiffFn(t *testing.T) {
+	const (
+		owner   = "octo"
+		repo    = "demo"
+		index   = 12
+		diffRaw = "diff --git a/file.txt b/file.txt\n+line\n"
+	)
+
+	var (
+		mu            sync.Mutex
+		diffRequested bool
+		binaryValue   string
+	)
+	errCh := make(chan error, 1)
+
+	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.URL.Path {
+		case "/api/v1/version":
+			w.Header().Set("Content-Type", "application/json")
+			_, _ = w.Write([]byte(`{"version":"1.12.0"}`))
+		case fmt.Sprintf("/api/v1/repos/%s/%s", owner, repo):
+			w.Header().Set("Content-Type", "application/json")
+			_, _ = w.Write([]byte(`{"private":false}`))
+		case fmt.Sprintf("/%s/%s/pulls/%d.diff", owner, repo, index):
+			if r.Method != http.MethodGet {
+				select {
+				case errCh <- fmt.Errorf("unexpected method: %s", r.Method):
+				default:
+				}
+			}
+			mu.Lock()
+			diffRequested = true
+			binaryValue = r.URL.Query().Get("binary")
+			mu.Unlock()
+			w.Header().Set("Content-Type", "text/plain")
+			_, _ = w.Write([]byte(diffRaw))
+		default:
+			select {
+			case errCh <- fmt.Errorf("unexpected request path: %s", r.URL.Path):
+			default:
+			}
+		}
+	})
+
+	server := httptest.NewServer(handler)
+	defer server.Close()
+
+	origHost := flag.Host
+	origToken := flag.Token
+	origVersion := flag.Version
+	flag.Host = server.URL
+	flag.Token = ""
+	flag.Version = "test"
+	defer func() {
+		flag.Host = origHost
+		flag.Token = origToken
+		flag.Version = origVersion
+	}()
+
+	req := mcp.CallToolRequest{
+		Params: mcp.CallToolParams{
+			Arguments: map[string]any{
+				"owner":  owner,
+				"repo":   repo,
+				"index":  float64(index),
+				"binary": true,
+			},
+		},
+	}
+
+	result, err := GetPullRequestDiffFn(context.Background(), req)
+	if err != nil {
+		t.Fatalf("GetPullRequestDiffFn() error = %v", err)
+	}
+
+	select {
+	case reqErr := <-errCh:
+		t.Fatalf("handler error: %v", reqErr)
+	default:
+	}
+
+	mu.Lock()
+	requested := diffRequested
+	gotBinary := binaryValue
+	mu.Unlock()
+
+	if !requested {
+		t.Fatalf("expected diff request to be made")
+	}
+	if gotBinary != "true" {
+		t.Fatalf("expected binary=true query param, got %q", gotBinary)
+	}
+
+	if len(result.Content) == 0 {
+		t.Fatalf("expected content in result")
+	}
+
+	textContent, ok := mcp.AsTextContent(result.Content[0])
+	if !ok {
+		t.Fatalf("expected text content, got %T", result.Content[0])
+	}
+
+	var parsed struct {
+		Result map[string]any `json:"Result"`
+	}
+	if err := json.Unmarshal([]byte(textContent.Text), &parsed); err != nil {
+		t.Fatalf("unmarshal result text: %v", err)
+	}
+
+	if got, ok := parsed.Result["diff"].(string); !ok || got != diffRaw {
+		t.Fatalf("diff = %q, want %q", got, diffRaw)
+	}
+	if got, ok := parsed.Result["binary"].(bool); !ok || got != true {
+		t.Fatalf("binary = %v, want true", got)
+	}
+	if got, ok := parsed.Result["index"].(float64); !ok || int64(got) != int64(index) {
+		t.Fatalf("index = %v, want %d", got, index)
+	}
+	if got, ok := parsed.Result["owner"].(string); !ok || got != owner {
+		t.Fatalf("owner = %q, want %q", got, owner)
+	}
+	if got, ok := parsed.Result["repo"].(string); !ok || got != repo {
+		t.Fatalf("repo = %q, want %q", got, repo)
+	}
+}