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)
	}
}