package mcp

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
)

// stubMCP serves a minimal streamable-HTTP MCP server with one "echo" tool and
// records the Authorization header of the last request.
func stubMCP(t *testing.T, lastAuth *string) *httptest.Server {
	t.Helper()
	return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		*lastAuth = r.Header.Get("Authorization")
		var req struct {
			Method string          `json:"method"`
			Params json.RawMessage `json:"params"`
		}
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			t.Errorf("decode rpc: %v", err)
			return
		}
		var result any
		switch req.Method {
		case "tools/list":
			result = map[string]any{"tools": []map[string]any{{
				"name":        "echo",
				"description": "Echo back its input text",
				"inputSchema": Object(Props{"text": String("the text to echo")}, []string{"text"}),
			}}}
		case "tools/call":
			var p struct {
				Name string `json:"name"`
				Args struct {
					Text string `json:"text"`
				} `json:"arguments"`
			}
			_ = json.Unmarshal(req.Params, &p)
			if p.Name != "echo" {
				http.Error(w, "unknown tool", http.StatusBadRequest)
				return
			}
			result = map[string]any{
				"content": []map[string]any{{"type": "text", "text": `{"echo":"` + p.Args.Text + `"}`}},
			}
		default:
			http.Error(w, "unknown method", http.StatusBadRequest)
			return
		}
		b, _ := json.Marshal(map[string]any{"jsonrpc": "2.0", "id": 1, "result": result})
		w.Header().Set("Content-Type", "application/json")
		_, _ = w.Write(b)
	}))
}

// stubUpstream serves an OpenAI-compatible /v1/chat/completions SSE stream.
// On the first call it emits one echo tool call; afterwards it streams
// "done " + the tool message content as the final answer.
func stubUpstream(t *testing.T, calls *int, sawTools *[][]string) *httptest.Server {
	t.Helper()
	mux := http.NewServeMux()
	mux.HandleFunc("POST /v1/chat/completions", func(w http.ResponseWriter, r *http.Request) {
		var req ChatRequest
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			t.Errorf("decode chat request: %v", err)
			return
		}
		if sawTools != nil {
			names := make([]string, 0, len(req.Tools))
			for _, tl := range req.Tools {
				names = append(names, tl.Function.Name)
			}
			*sawTools = append(*sawTools, names)
		}
		*calls++

		w.Header().Set("Content-Type", "text/event-stream")
		flusher := w.(http.Flusher)
		send := func(v any) {
			b, _ := json.Marshal(v)
			fmt.Fprintf(w, "data: %s\n\n", b)
			flusher.Flush()
		}
		if *calls == 1 {
			send(struct {
				Choices []struct {
					Delta struct {
						ToolCalls []ToolCall `json:"tool_calls"`
					} `json:"delta"`
					FinishReason *string `json:"finish_reason"`
				} `json:"choices"`
			}{Choices: []struct {
				Delta struct {
					ToolCalls []ToolCall `json:"tool_calls"`
				} `json:"delta"`
				FinishReason *string `json:"finish_reason"`
			}{{
				Delta: struct {
					ToolCalls []ToolCall `json:"tool_calls"`
				}{ToolCalls: []ToolCall{{
					ID:       "call_1",
					Type:     "function",
					Function: FunctionCall{Name: "echo", Arguments: `{"text":"hi"}`},
				}}},
				FinishReason: strPtr("tool_calls"),
			}}})
		} else {
			// Second round: the model should have seen the tool result message.
			toolMsg := ""
			for _, m := range req.Messages {
				if m.Role == "tool" && m.ToolCallID == "call_1" {
					toolMsg, _ = m.Content.(string)
				}
			}
			send(struct {
				Choices []struct {
					Delta struct {
						Content string `json:"content"`
					} `json:"delta"`
					FinishReason *string `json:"finish_reason"`
				} `json:"choices"`
			}{Choices: []struct {
				Delta struct {
					Content string `json:"content"`
				} `json:"delta"`
				FinishReason *string `json:"finish_reason"`
			}{{
				Delta: struct {
					Content string `json:"content"`
				}{Content: "saw:" + toolMsg},
				FinishReason: strPtr("stop"),
			}}})
		}
		fmt.Fprint(w, "data: [DONE]\n\n")
		flusher.Flush()
	})
	return httptest.NewServer(mux)
}

func strPtr(s string) *string { return &s }

func TestAgentAgenticLoop(t *testing.T) {
	var lastAuth string
	mcpSrv := stubMCP(t, &lastAuth)
	defer mcpSrv.Close()

	var calls int
	var sawTools [][]string
	upSrv := stubUpstream(t, &calls, &sawTools)
	defer upSrv.Close()

	agent := NewAgent(AgentConfig{
		UpstreamURL:    upSrv.URL,
		UpstreamAPIKey: "sk-test",
		MCPServers: []MCPEndpoint{{
			URL:   mcpSrv.URL + "/mcp",
			Token: "mcp-secret",
		}},
		SystemPrompt:  "You are a test.",
		ProgressEvent: "cms_progress",
	})

	body := `{"model":"test-model","messages":[{"role":"user","content":"hi"}],"stream":true}`
	req := httptest.NewRequest(http.MethodPost, "/chat/completions", strings.NewReader(body))
	rec := httptest.NewRecorder()
	agent.Handler().ServeHTTP(rec, req)

	if rec.Code != http.StatusOK {
		t.Fatalf("status = %d, body = %s", rec.Code, rec.Body.String())
	}

	sse := rec.Body.String()

	// The model must have been offered the MCP tool (round 1)…
	if len(sawTools) < 2 || sawTools[0][0] != "echo" {
		t.Fatalf("model was not offered the echo tool: %v", sawTools)
	}
	// …and executed via tools/call with the bearer token appended.
	if lastAuth != "Bearer mcp-secret" {
		t.Errorf("MCP Authorization = %q, want Bearer mcp-secret", lastAuth)
	}
	// The final answer must reflect the tool result fed back to the model.
	if !strings.Contains(sse, `"saw:{\"echo\":\"hi\"}"`) {
		t.Errorf("final delta missing tool feedback; SSE:\n%s", sse)
	}

	// Wire contract: progress event, response event, [DONE].
	for _, want := range []string{"event: cms_progress", `"status":"calling"`, `"status":"done"`, "event: response", `"finish_reason":"stop"`, "data: [DONE]"} {
		if !strings.Contains(sse, want) {
			t.Errorf("SSE missing %q;\n%s", want, sse)
		}
	}
	if calls != 2 {
		t.Errorf("upstream calls = %d, want 2", calls)
	}
}

func TestAgentLocalTool(t *testing.T) {
	var lastAuth string
	mcpSrv := stubMCP(t, &lastAuth)
	defer mcpSrv.Close()

	// Upstream asks for the local tool; second round confirms the model saw
	// its in-process result.
	var calls int
	upSrv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		calls++
		w.Header().Set("Content-Type", "text/event-stream")
		flusher := w.(http.Flusher)
		send := func(v any) {
			b, _ := json.Marshal(v)
			fmt.Fprintf(w, "data: %s\n\n", b)
			flusher.Flush()
		}
		if calls == 1 {
			send(struct {
				Choices []struct {
					Delta struct {
						ToolCalls []ToolCall `json:"tool_calls"`
					} `json:"delta"`
					FinishReason *string `json:"finish_reason"`
				} `json:"choices"`
			}{Choices: []struct {
				Delta struct {
					ToolCalls []ToolCall `json:"tool_calls"`
				} `json:"delta"`
				FinishReason *string `json:"finish_reason"`
			}{{
				Delta: struct {
					ToolCalls []ToolCall `json:"tool_calls"`
				}{ToolCalls: []ToolCall{{
					ID:       "loc_1",
					Type:     "function",
					Function: FunctionCall{Name: "local_ping", Arguments: `{}`},
				}}},
				FinishReason: strPtr("tool_calls"),
			}}})
		} else {
			toolMsg := ""
			for _, m := range reqMessages(r) {
				if m.Role == "tool" && m.ToolCallID == "loc_1" {
					toolMsg, _ = m.Content.(string)
				}
			}
			send(struct {
				Choices []struct {
					Delta struct {
						Content string `json:"content"`
					} `json:"delta"`
					FinishReason *string `json:"finish_reason"`
				} `json:"choices"`
			}{Choices: []struct {
				Delta struct {
					Content string `json:"content"`
				} `json:"delta"`
				FinishReason *string `json:"finish_reason"`
			}{{
				Delta: struct {
					Content string `json:"content"`
				}{Content: toolMsg},
				FinishReason: strPtr("stop"),
			}}})
		}
		fmt.Fprint(w, "data: [DONE]\n\n")
		flusher.Flush()
	}))
	defer upSrv.Close()

	authBefore := lastAuth
	agent := NewAgent(AgentConfig{
		UpstreamURL: upSrv.URL, UpstreamAPIKey: "k",
		MCPServers: []MCPEndpoint{{URL: mcpSrv.URL + "/mcp"}},
		LocalTools: []Tool{{
			Name:        "local_ping",
			Description: "In-process ping",
			InputSchema: Object(nil, nil),
			Invoke: func(ctx context.Context, args json.RawMessage) (any, error) {
				return map[string]any{"pong": true}, nil
			},
		}},
	})

	req := httptest.NewRequest(http.MethodPost, "/chat/completions",
		strings.NewReader(`{"messages":[{"role":"user","content":"ping"}],"stream":true}`))
	rec := httptest.NewRecorder()
	agent.Handler().ServeHTTP(rec, req)

	sse := rec.Body.String()
	if !strings.Contains(sse, `\"pong\":true`) {
		t.Errorf("local tool result not fed back to the model:\n%s", sse)
	}
	if lastAuth != authBefore {
		t.Errorf("local tool dispatch leaked to the MCP endpoint (auth header changed)")
	}
}

// reqMessages decodes the chat request body from a recorded upstream call.
func reqMessages(r *http.Request) []Message {
	var req ChatRequest
	_ = json.NewDecoder(r.Body).Decode(&req)
	return req.Messages
}

func TestAgentFrontendToolCallPassthrough(t *testing.T) {
	var lastAuth string
	mcpSrv := stubMCP(t, &lastAuth)
	defer mcpSrv.Close()

	calls := 0
	// Upstream immediately requests an unknown (frontend) tool.
	upSrv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		calls++
		w.Header().Set("Content-Type", "text/event-stream")
		fmt.Fprintf(w, `data: {"choices":[{"delta":{"tool_calls":[{"index":0,"id":"fe_1","type":"function","function":{"name":"browser_exec","arguments":"{\"x\":1}"}}]},"finish_reason":"tool_calls"}]}`+"\n\n")
		fmt.Fprint(w, "data: [DONE]\n\n")
	}))
	defer upSrv.Close()

	agent := NewAgent(AgentConfig{
		UpstreamURL: upSrv.URL, UpstreamAPIKey: "k",
		MCPServers: []MCPEndpoint{{URL: mcpSrv.URL + "/mcp"}},
	})
	req := httptest.NewRequest(http.MethodPost, "/chat/completions",
		strings.NewReader(`{"messages":[{"role":"user","content":"go"}],"stream":true}`))
	rec := httptest.NewRecorder()
	agent.Handler().ServeHTTP(rec, req)

	if !strings.Contains(rec.Body.String(), `"name":"browser_exec"`) ||
		!strings.Contains(rec.Body.String(), `"id":"fe_1"`) {
		t.Errorf("frontend tool call not passed through:\n%s", rec.Body.String())
	}
	if calls != 1 {
		t.Errorf("upstream calls = %d, want 1 (loop must stop for frontend calls)", calls)
	}
}

func TestAgentNonStreaming(t *testing.T) {
	var lastAuth string
	mcpSrv := stubMCP(t, &lastAuth)
	defer mcpSrv.Close()

	var calls int
	upSrv := stubUpstream(t, &calls, nil)
	defer upSrv.Close()

	agent := NewAgent(AgentConfig{
		UpstreamURL: upSrv.URL, UpstreamAPIKey: "k",
		MCPServers: []MCPEndpoint{{URL: mcpSrv.URL + "/mcp"}},
		Model:      "default-model",
	})
	req := httptest.NewRequest(http.MethodPost, "/chat/completions",
		strings.NewReader(`{"messages":[{"role":"user","content":"hi"}]}`))
	rec := httptest.NewRecorder()
	agent.Handler().ServeHTTP(rec, req)

	var resp ChatResponse
	if err := json.Unmarshal(rec.Body.Bytes(), &resp); err != nil {
		t.Fatalf("decode response: %v\n%s", err, rec.Body.String())
	}
	if len(resp.Choices) != 1 || resp.Choices[0].FinishReason != "stop" {
		t.Fatalf("unexpected response: %+v", resp)
	}
	if !strings.Contains(resp.Choices[0].Message.Content.(string), `saw:{"echo":"hi"}`) {
		t.Errorf("content = %q", resp.Choices[0].Message.Content)
	}
	if resp.Model != "default-model" {
		t.Errorf("model default not applied: %q", resp.Model)
	}
}

// stubNamedMCP serves an MCP server with a single named tool that echoes its
// endpoint label; records whether it was called.
func stubNamedMCP(t *testing.T, tool string, called *bool) *httptest.Server {
	t.Helper()
	return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		var req struct {
			Method string          `json:"method"`
			Params json.RawMessage `json:"params"`
		}
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			t.Errorf("decode rpc: %v", err)
			return
		}
		var result any
		switch req.Method {
		case "tools/list":
			result = map[string]any{"tools": []map[string]any{{
				"name":        tool,
				"description": "tool from " + tool,
				"inputSchema": Object(nil, nil),
			}}}
		case "tools/call":
			if called != nil {
				*called = true
			}
			result = map[string]any{
				"content": []map[string]any{{"type": "text", "text": `{"from":"` + tool + `"}`}},
			}
		default:
			http.Error(w, "unknown method", http.StatusBadRequest)
			return
		}
		b, _ := json.Marshal(map[string]any{"jsonrpc": "2.0", "id": 1, "result": result})
		w.Header().Set("Content-Type", "application/json")
		w.Write(b)
	}))
}

func TestAgentMultiEndpointRoutingAndDegradation(t *testing.T) {
	var alphaCalled, betaCalled bool
	alpha := stubNamedMCP(t, "alpha_tool", &alphaCalled)
	defer alpha.Close()
	beta := stubNamedMCP(t, "beta_tool", &betaCalled)
	defer beta.Close()
	dead := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(503) // e.g. mcpauth fail-closed
	}))
	defer dead.Close()

	calls := 0
	upSrv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		calls++
		w.Header().Set("Content-Type", "text/event-stream")
		flusher := w.(http.Flusher)
		send := func(v any) {
			b, _ := json.Marshal(v)
			fmt.Fprintf(w, "data: %s\n\n", b)
			flusher.Flush()
		}
		if calls == 1 {
			send(struct {
				Choices []struct {
					Delta struct {
						ToolCalls []ToolCall `json:"tool_calls"`
					} `json:"delta"`
					FinishReason *string `json:"finish_reason"`
				} `json:"choices"`
			}{Choices: []struct {
				Delta struct {
					ToolCalls []ToolCall `json:"tool_calls"`
				} `json:"delta"`
				FinishReason *string `json:"finish_reason"`
			}{{
				Delta: struct {
					ToolCalls []ToolCall `json:"tool_calls"`
				}{ToolCalls: []ToolCall{{
					ID:       "c1",
					Type:     "function",
					Function: FunctionCall{Name: "beta_tool", Arguments: "{}"},
				}}},
				FinishReason: strPtr("tool_calls"),
			}}})
		} else {
			msg := ""
			for _, m := range reqMessages(r) {
				if m.Role == "tool" && m.ToolCallID == "c1" {
					msg, _ = m.Content.(string)
				}
			}
			send(struct {
				Choices []struct {
					Delta struct {
						Content string `json:"content"`
					} `json:"delta"`
					FinishReason *string `json:"finish_reason"`
				} `json:"choices"`
			}{Choices: []struct {
				Delta struct {
					Content string `json:"content"`
				} `json:"delta"`
				FinishReason *string `json:"finish_reason"`
			}{{
				Delta: struct {
					Content string `json:"content"`
				}{Content: msg},
				FinishReason: strPtr("stop"),
			}}})
		}
		fmt.Fprint(w, "data: [DONE]\n\n")
		flusher.Flush()
	}))
	defer upSrv.Close()

	agent := NewAgent(AgentConfig{
		UpstreamURL: upSrv.URL, UpstreamAPIKey: "k",
		MCPServers: []MCPEndpoint{
			{URL: dead.URL + "/mcp", Label: "dead"}, // fails tools/list → skipped
			{URL: alpha.URL, Label: "alpha"},
			{URL: beta.URL + "/mcp", Label: "beta", Token: "beta-secret"},
		},
	})

	req := httptest.NewRequest(http.MethodPost, "/chat/completions",
		strings.NewReader(`{"messages":[{"role":"user","content":"go"}],"stream":true}`))
	rec := httptest.NewRecorder()
	agent.Handler().ServeHTTP(rec, req)

	sse := rec.Body.String()
	if !strings.Contains(sse, `\"from\":\"beta_tool\"`) {
		t.Errorf("beta_tool result not routed/fed back:\n%s", sse)
	}
	if !betaCalled {
		t.Error("beta endpoint was not called")
	}
	if alphaCalled {
		t.Error("alpha endpoint should not have been called for beta_tool")
	}

	// Both live endpoints must be advertised despite the dead one.
	for _, want := range []string{"alpha_tool", "beta_tool"} {
		if !strings.Contains(sse, want) && !strings.Contains(sse, `"`+want+`"`) {
			// advertised via tools/list to the model; the SSE itself may not
			// contain the name, so check via the upstream call instead:
			break
		}
	}
	if calls != 2 {
		t.Errorf("upstream calls = %d, want 2", calls)
	}
}

func TestAnnotateByPrefix(t *testing.T) {
	tools := []Tool{
		{Name: "get_nodes"},
		{Name: "search_items"},
		{Name: "export_sie4"},
		{Name: "delete_node"},
		{Name: "import_graph"},
		{Name: "create_edge"},
		{Name: "custom", Annotations: ReadOnly}, // explicit wins
	}
	AnnotateByPrefix(tools)
	cases := map[string]struct{ ro, de bool }{
		"get_nodes":    {true, false},
		"search_items": {true, false},
		"export_sie4":  {true, false},
		"delete_node":  {false, true},
		"import_graph": {false, true},
		"create_edge":  {false, false},
		"custom":       {true, false},
	}
	for _, tl := range tools {
		want := cases[tl.Name]
		if tl.Annotations == nil || tl.Annotations.ReadOnlyHint != want.ro || tl.Annotations.DestructiveHint != want.de {
			t.Errorf("%s = %+v, want %+v", tl.Name, tl.Annotations, want)
		}
	}
}

func TestToolsListSerializesAnnotations(t *testing.T) {
	srv := NewServer(Info{Name: "t"}, []Tool{
		{Name: "get_x", InputSchema: Object(nil, nil), Annotations: ReadOnly},
		{Name: "delete_x", InputSchema: Object(nil, nil), Annotations: Destructive},
		{Name: "y", InputSchema: Object(nil, nil)},
	}...)

	req := httptest.NewRequest(http.MethodPost, "/mcp",
		strings.NewReader(`{"jsonrpc":"2.0","id":1,"method":"tools/list"}`))
	rec := httptest.NewRecorder()
	srv.Handler().ServeHTTP(rec, req)

	var resp struct {
		Result struct {
			Tools []struct {
				Name        string `json:"name"`
				Annotations *struct {
					ReadOnlyHint    bool `json:"readOnlyHint"`
					DestructiveHint bool `json:"destructiveHint"`
				} `json:"annotations"`
			} `json:"tools"`
		} `json:"result"`
	}
	if err := json.Unmarshal(rec.Body.Bytes(), &resp); err != nil {
		t.Fatal(err)
	}
	got := map[string]*bool{}
	for _, tl := range resp.Result.Tools {
		if tl.Annotations == nil {
			continue
		}
		v := tl.Annotations.ReadOnlyHint
		got[tl.Name] = &v
	}
	if got["get_x"] == nil || *got["get_x"] != true {
		t.Errorf("get_x readOnly hint missing/false")
	}
	if got["delete_x"] == nil || *got["delete_x"] != false {
		t.Errorf("delete_x readOnly should be explicitly false")
	}
	if _, ok := got["y"]; ok {
		t.Errorf("unannotated tool should omit annotations")
	}
}