package bridge_test

import (
	"context"
	"io"
	"net/http"
	"net/http/httptest"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"kode.naiv.no/olemd/forgejo-mcp-broker/internal/bridge"
	brokerlog "kode.naiv.no/olemd/forgejo-mcp-broker/internal/log"
	"kode.naiv.no/olemd/forgejo-mcp-broker/internal/supervisor"
)

// TestBridge_AgainstRealForgejoMCP is the phase-4b acceptance test. It
// drives a real `forgejo-mcp --transport stdio` subprocess through the
// bridge and runs the canonical MCP handshake plus a tool call that
// doesn't require Forgejo network access.
//
// Skipped under -short. Skipped entirely when no forgejo-mcp binary or
// source tree is available — see findOrBuildForgejoMCP for the search.
//
// Driving the bridge confirms the opaque-pipe assumption holds in
// practice: every JSON-RPC message we forward to the child gets a
// response routed by id, with no protocol-level surprises.
func TestBridge_AgainstRealForgejoMCP(t *testing.T) {
	if testing.Short() {
		t.Skip("integration test (~3s); rerun without -short")
	}

	binPath := findOrBuildForgejoMCP(t)

	// forgejo-mcp probes Forgejo (GET /api/v1/user) at startup. Stand up a
	// minimal fake instead of requiring a real Forgejo deployment.
	fakeForgejo := newFakeForgejoServer(t)

	child, err := supervisor.Start(t.Context(), supervisor.Config{
		Cmd: []string{binPath, "--transport", "stdio", "--url", fakeForgejo.URL},
		Env: []string{
			"FORGEJO_ACCESS_TOKEN=integration-test-token",
		},
		OnStderr: func(line string) { t.Logf("forgejo-mcp[stderr]: %s", line) },
	})
	if err != nil {
		t.Fatalf("Start forgejo-mcp: %v", err)
	}
	t.Cleanup(func() {
		stopCtx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
		defer cancel()
		_ = child.Stop(stopCtx)
	})

	b := bridge.New(child.Stdin, child.Stdout, child.Done(), brokerlog.Discard())
	b.Start()

	srv := httptest.NewServer(http.HandlerFunc(b.HandleSSE))
	t.Cleanup(srv.Close)

	// 1. initialize — kicks off the MCP handshake.
	initBody := `{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"fjmcp-broker-test","version":"1"}}}`
	initResp := postSSEMustOK(t, srv.URL, initBody)
	if !strings.Contains(initResp, `"protocolVersion"`) {
		t.Errorf("initialize response missing protocolVersion: %s", initResp)
	}
	if !strings.Contains(initResp, `"serverInfo"`) {
		t.Errorf("initialize response missing serverInfo: %s", initResp)
	}

	// 2. notifications/initialized — required by the MCP spec before any
	// further requests. Bridge returns 204 for notifications.
	notified := postBody(t, srv.URL, `{"jsonrpc":"2.0","method":"notifications/initialized"}`)
	if notified.StatusCode != http.StatusNoContent {
		t.Errorf("notifications/initialized status = %d, want 204", notified.StatusCode)
	}

	// 3. tools/list — must include the version tool.
	listBody := `{"jsonrpc":"2.0","id":2,"method":"tools/list"}`
	listResp := postSSEMustOK(t, srv.URL, listBody)
	if !strings.Contains(listResp, "get_forgejo_mcp_server_version") {
		t.Errorf("tools/list missing get_forgejo_mcp_server_version. Body: %s", listResp)
	}

	// 4. tools/call get_forgejo_mcp_server_version — does no Forgejo
	// network work, so the fake instance is irrelevant here. We just
	// confirm the call succeeds and a result comes back.
	callBody := `{"jsonrpc":"2.0","id":3,"method":"tools/call","params":{"name":"get_forgejo_mcp_server_version","arguments":{}}}`
	callResp := postSSEMustOK(t, srv.URL, callBody)
	if !strings.Contains(callResp, `"content"`) {
		t.Errorf("tools/call response missing content. Body: %s", callResp)
	}
	// Sanity: response should not be an error.
	if strings.Contains(callResp, `"isError":true`) {
		t.Errorf("tools/call returned isError=true. Body: %s", callResp)
	}
}

// findOrBuildForgejoMCP locates a forgejo-mcp binary the test can spawn.
// Search order:
//  1. $FORGEJO_MCP_BIN
//  2. ../../../forgejo-mcp/forgejo-mcp (sibling repo with a built binary)
//  3. go build of ../../../forgejo-mcp into a temp dir
// Skips the test (not fails) if none of those work.
func findOrBuildForgejoMCP(t *testing.T) string {
	t.Helper()

	if p := os.Getenv("FORGEJO_MCP_BIN"); p != "" {
		if _, err := os.Stat(p); err == nil {
			return p
		}
		t.Skipf("FORGEJO_MCP_BIN=%q does not exist", p)
	}

	// Sibling-repo binary.
	if abs, err := filepath.Abs("../../../forgejo-mcp/forgejo-mcp"); err == nil {
		if _, err := os.Stat(abs); err == nil {
			return abs
		}
	}

	// Sibling-repo source build.
	if abs, err := filepath.Abs("../../../forgejo-mcp"); err == nil {
		if _, err := os.Stat(filepath.Join(abs, "main.go")); err == nil {
			bin := filepath.Join(t.TempDir(), "forgejo-mcp")
			build := exec.Command("go", "build", "-o", bin, ".")
			build.Dir = abs
			build.Env = os.Environ()
			out, err := build.CombinedOutput()
			if err != nil {
				t.Skipf("go build of sibling forgejo-mcp failed: %v\n%s", err, out)
			}
			return bin
		}
	}

	t.Skip("forgejo-mcp binary not found: set $FORGEJO_MCP_BIN or place a sibling repo at ../forgejo-mcp")
	return ""
}

// newFakeForgejoServer stands up the minimum Forgejo API surface
// forgejo-mcp probes during startup:
//   - GET /api/v1/version — the SDK requires the server be >= 1.11.0
//   - GET /api/v1/user    — VerifyConnection's authenticated probe
//
// Any other path responds 404 with a t.Log so future probes added
// upstream show up clearly in test output.
func newFakeForgejoServer(t *testing.T) *httptest.Server {
	t.Helper()
	mux := http.NewServeMux()
	mux.HandleFunc("/api/v1/version", func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		_, _ = io.WriteString(w, `{"version":"11.0.0"}`)
	})
	mux.HandleFunc("/api/v1/user", func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		_, _ = io.WriteString(w, `{"id":1,"login":"integration-tester","username":"integration-tester","full_name":"Integration Tester","email":"itester@example.com","avatar_url":"https://example.com/a.png"}`)
	})
	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		t.Logf("fake forgejo: unexpected probe %s %s", r.Method, r.URL.Path)
		w.WriteHeader(http.StatusNotFound)
	})
	srv := httptest.NewServer(mux)
	t.Cleanup(srv.Close)
	return srv
}

// postSSEMustOK posts a JSON-RPC body, expects a 200 + text/event-stream
// response, and returns the raw body. Fails the test on any other shape.
func postSSEMustOK(t *testing.T, url, body string) string {
	t.Helper()
	resp := postBody(t, url, body)
	defer resp.Body.Close()
	b, _ := io.ReadAll(resp.Body)
	if resp.StatusCode != http.StatusOK {
		t.Fatalf("POST %s: status %d, body %s", url, resp.StatusCode, b)
	}
	if ct := resp.Header.Get("Content-Type"); !strings.HasPrefix(ct, "text/event-stream") {
		t.Fatalf("POST %s: Content-Type %q, want text/event-stream", url, ct)
	}
	return string(b)
}

func postBody(t *testing.T, url, body string) *http.Response {
	t.Helper()
	req, err := http.NewRequestWithContext(t.Context(), http.MethodPost, url, strings.NewReader(body))
	if err != nil {
		t.Fatalf("build request: %v", err)
	}
	req.Header.Set("Content-Type", "application/json")
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("POST: %v", err)
	}
	return resp
}