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package handler_test

import (
    "encoding/json"
    "net/http"
    "net/http/httptest"
    "testing"
)

type UserStore interface {
    GetUser(id int) (string, bool)
}

type fakeStore struct {
    users map[int]string
}

func (f *fakeStore) GetUser(id int) (string, bool) {
    name, ok := f.users[id]
    return name, ok
}

func userHandler(store UserStore) http.HandlerFunc {
    return func(w http.ResponseWriter, r *http.Request) {
        id := 1 // simplified; real code uses r.PathValue
        name, ok := store.GetUser(id)
        if !ok {
            http.NotFound(w, r)
            return
        }
        w.Header().Set("Content-Type", "application/json")
        json.NewEncoder(w).Encode(map[string]string{"name": name})
    }
}

func TestUserHandler(t *testing.T) {
    store := &fakeStore{users: map[int]string{1: "Alice"}}
    handler := userHandler(store)

// Unit-level: recorder test
    req  := httptest.NewRequest(http.MethodGet, "/users/1", nil)
    rec  := httptest.NewRecorder()
    handler.ServeHTTP(rec, req)

if rec.Code != http.StatusOK {
        t.Errorf("expected 200, got %d", rec.Code)
    }
    var body map[string]string
    json.NewDecoder(rec.Body).Decode(&body)
    if body["name"] != "Alice" {
        t.Errorf("expected Alice, got %q", body["name"])
    }

// Integration-level: real server
    ts := httptest.NewServer(handler)
    defer ts.Close()

resp, _ := http.Get(ts.URL + "/users/1")
    defer resp.Body.Close()
    if resp.StatusCode != http.StatusOK {
        t.Errorf("server test: expected 200, got %d", resp.StatusCode)
    }
}