package api

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"

	"github.com/gin-gonic/gin"
	"github.com/gorilla/websocket"

	"monica-go-completion-backend/internal/completion"
)

type fakeCompletionService struct {
	resp completion.Response
	err  error
}

func (f *fakeCompletionService) Complete(_ context.Context, _ completion.Request) (completion.Response, error) {
	if f.err != nil {
		return completion.Response{}, f.err
	}
	return f.resp, nil
}

// 验证 HTTP 补全接口的成功路径。
func TestRegisterRoutesCompletionSuccess(t *testing.T) {
	gin.SetMode(gin.TestMode)
	r := gin.New()
	RegisterRoutes(r, &fakeCompletionService{
		resp: completion.Response{Items: []completion.Item{{Label: "Println"}}, IsIncomplete: true},
	})

	body, _ := json.Marshal(map[string]any{
		"uri":       "file:///main.go",
		"text":      "package main",
		"line":      0,
		"character": 0,
	})

	req := httptest.NewRequest(http.MethodPost, "/api/v1/completions/go", bytes.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	w := httptest.NewRecorder()
	r.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected status 200, got %d", w.Code)
	}

	var got struct {
		Items        []completion.Item `json:"items"`
		IsIncomplete bool              `json:"isIncomplete"`
	}
	if err := json.Unmarshal(w.Body.Bytes(), &got); err != nil {
		t.Fatalf("failed to decode response: %v", err)
	}
	if len(got.Items) != 1 || got.Items[0].Label != "Println" || !got.IsIncomplete {
		t.Fatalf("unexpected response body: %s", w.Body.String())
	}
}

// 验证非法 JSON 会返回 400。
func TestRegisterRoutesCompletionBadJSON(t *testing.T) {
	gin.SetMode(gin.TestMode)
	r := gin.New()
	RegisterRoutes(r, &fakeCompletionService{})

	req := httptest.NewRequest(http.MethodPost, "/api/v1/completions/go", bytes.NewReader([]byte("not-json")))
	req.Header.Set("Content-Type", "application/json")
	w := httptest.NewRecorder()
	r.ServeHTTP(w, req)

	if w.Code != http.StatusBadRequest {
		t.Fatalf("expected status 400, got %d", w.Code)
	}
}

// 验证业务校验错误会映射为 400。
func TestRegisterRoutesCompletionValidationError(t *testing.T) {
	gin.SetMode(gin.TestMode)
	r := gin.New()
	rv := &fakeCompletionService{err: completion.ErrInvalidRequest}
	RegisterRoutes(r, rv)

	body, _ := json.Marshal(map[string]any{
		"uri":       "",
		"text":      "",
		"line":      -1,
		"character": 0,
	})
	w := httptest.NewRecorder()
	req := httptest.NewRequest(http.MethodPost, "/api/v1/completions/go", bytes.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	r.ServeHTTP(w, req)

	if w.Code != http.StatusBadRequest {
		t.Fatalf("expected status 400, got %d", w.Code)
	}
}

// 验证未知内部错误会映射为 500。
func TestRegisterRoutesCompletionServerError(t *testing.T) {
	gin.SetMode(gin.TestMode)
	r := gin.New()
	RegisterRoutes(r, &fakeCompletionService{err: errors.New("boom")})

	body, _ := json.Marshal(map[string]any{
		"uri":       "file:///main.go",
		"text":      "package main",
		"line":      0,
		"character": 0,
	})
	w := httptest.NewRecorder()
	req := httptest.NewRequest(http.MethodPost, "/api/v1/completions/go", bytes.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	r.ServeHTTP(w, req)

	if w.Code != http.StatusInternalServerError {
		t.Fatalf("expected status 500, got %d", w.Code)
	}
}

// 验证 WebSocket 补全协议的基础成功流程。
func TestRegisterRoutesCompletionWebSocketSuccess(t *testing.T) {
	gin.SetMode(gin.TestMode)
	r := gin.New()
	RegisterRoutes(r, &fakeCompletionService{
		resp: completion.Response{Items: []completion.Item{{Label: "Println"}}, IsIncomplete: false},
	})

	srv := httptest.NewServer(r)
	defer srv.Close()

	wsURL := "ws" + strings.TrimPrefix(srv.URL, "http") + "/ws/completions/go"
	conn, _, err := websocket.DefaultDialer.Dial(wsURL, nil)
	if err != nil {
		t.Fatalf("websocket dial failed: %v", err)
	}
	defer conn.Close()

	req := map[string]any{
		"id":        "1",
		"uri":       "file:///main.go",
		"text":      "package main",
		"line":      0,
		"character": 0,
	}
	if err := conn.WriteJSON(req); err != nil {
		t.Fatalf("WriteJSON() failed: %v", err)
	}

	var resp struct {
		ID           string            `json:"id"`
		Items        []completion.Item `json:"items"`
		IsIncomplete bool              `json:"isIncomplete"`
		Error        string            `json:"error"`
	}
	if err := conn.ReadJSON(&resp); err != nil {
		t.Fatalf("ReadJSON() failed: %v", err)
	}

	if resp.Error != "" {
		t.Fatalf("unexpected websocket error: %s", resp.Error)
	}
	if resp.ID != "1" {
		t.Fatalf("unexpected id: %s", resp.ID)
	}
	if len(resp.Items) != 1 || resp.Items[0].Label != "Println" {
		t.Fatalf("unexpected items: %+v", resp.Items)
	}
}