package handler

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

	"5803025015/w04/internal/middleware"
	"5803025015/w04/internal/models"
)

// ---------- helpers ----------

func setupSnippetHandler() (*SnippetHandler, *fakeSnippetStore) {
	ss := newFakeSnippetStore()
	return NewSnippetHandler(ss), ss
}

// withUserID injects user_id into request context (simulating middleware).
func withUserID(r *http.Request, userID string) *http.Request {
	ctx := context.WithValue(r.Context(), middleware.UserIDKey, userID)
	return r.WithContext(ctx)
}

// doSnippetRequest fires handler with optional user_id injected.
func doSnippetRequest(
	h http.HandlerFunc,
	method, path string,
	body []byte,
	userID string,
) *httptest.ResponseRecorder {
	req := httptest.NewRequest(method, path, bytes.NewReader(body))
	if userID != "" {
		req = withUserID(req, userID)
	}
	rec := httptest.NewRecorder()
	h(rec, req)
	return rec
}

// decodeSnippetMap decodes into map[string]any to check EXACT key set.
func decodeSnippetMap(t *testing.T, body []byte) map[string]any {
	t.Helper()
	var m map[string]any
	if err := json.Unmarshal(body, &m); err != nil {
		t.Fatalf("body not valid JSON: %v; body=%q", err, string(body))
	}
	return m
}

// ---------- TestCreateSnippet ----------

func TestCreateSnippet(t *testing.T) {
	t.Run("success -> 201 with exactly id, title, content", func(t *testing.T) {
		h, _ := setupSnippetHandler()
		rec := doSnippetRequest(h.Create, http.MethodPost, "/snippets",
			[]byte(`{"title":"hello","content":"world"}`), "u1")
		if rec.Code != http.StatusCreated {
			t.Fatalf("want 201, got %d (body=%s)", rec.Code, rec.Body.String())
		}
		assertContentTypeJSON(t, rec)
		m := decodeSnippetMap(t, rec.Body.Bytes())
		if len(m) != 3 {
			t.Fatalf("want exactly 3 keys, got %d: %v", len(m), m)
		}
		for _, k := range []string{"id", "title", "content"} {
			if _, ok := m[k]; !ok {
				t.Fatalf("missing key %q in %v", k, m)
			}
		}
		if _, extra := m["user_id"]; extra {
			t.Fatal("response should not have user_id key")
		}
	})

	t.Run("empty title -> 400", func(t *testing.T) {
		h, _ := setupSnippetHandler()
		rec := doSnippetRequest(h.Create, http.MethodPost, "/snippets",
			[]byte(`{"title":"","content":"world"}`), "u1")
		if rec.Code != http.StatusBadRequest {
			t.Fatalf("want 400, got %d", rec.Code)
		}
		assertContentTypeJSON(t, rec)
	})

	t.Run("empty content -> 400", func(t *testing.T) {
		h, _ := setupSnippetHandler()
		rec := doSnippetRequest(h.Create, http.MethodPost, "/snippets",
			[]byte(`{"title":"hello","content":""}`), "u1")
		if rec.Code != http.StatusBadRequest {
			t.Fatalf("want 400, got %d", rec.Code)
		}
		assertContentTypeJSON(t, rec)
	})

	t.Run("malformed JSON -> 400", func(t *testing.T) {
		h, _ := setupSnippetHandler()
		rec := doSnippetRequest(h.Create, http.MethodPost, "/snippets",
			[]byte(`{"title":"hello"`), "u1")
		if rec.Code != http.StatusBadRequest {
			t.Fatalf("want 400, got %d", rec.Code)
		}
		assertContentTypeJSON(t, rec)
	})

	t.Run("unauthenticated -> 401", func(t *testing.T) {
		h, _ := setupSnippetHandler()
		rec := doSnippetRequest(h.Create, http.MethodPost, "/snippets",
			[]byte(`{"title":"hello","content":"world"}`), "") // no user_id
		if rec.Code != http.StatusUnauthorized {
			t.Fatalf("want 401, got %d", rec.Code)
		}
		assertContentTypeJSON(t, rec)
	})
}

// ---------- TestGetSnippet ----------

func TestGetSnippet(t *testing.T) {
	t.Run("existing id -> 200 without Authorization header", func(t *testing.T) {
		h, store := setupSnippetHandler()
		_ = store.Create(nil, &models.Snippet{ID: "s1", Title: "t", Content: "c", UserID: "owner"})

		// PathValue needs Go 1.22; simulate via SetPathValue on the request
		rec := doSnippetRequest(h.Get, http.MethodGet, "/snippets/s1", nil, "")
		if rec.Code != http.StatusOK {
			t.Fatalf("want 200, got %d (body=%s)", rec.Code, rec.Body.String())
		}
		assertContentTypeJSON(t, rec)
	})

	t.Run("missing id -> 404", func(t *testing.T) {
		h, _ := setupSnippetHandler()
		rec := doSnippetRequest(h.Get, http.MethodGet, "/snippets/ghost", nil, "")
		if rec.Code != http.StatusNotFound {
			t.Fatalf("want 404, got %d", rec.Code)
		}
		assertContentTypeJSON(t, rec)
	})

	t.Run("response has exactly id, title, content keys", func(t *testing.T) {
		h, store := setupSnippetHandler()
		_ = store.Create(nil, &models.Snippet{ID: "s2", Title: "t", Content: "c", UserID: "owner"})

		rec := doSnippetRequest(h.Get, http.MethodGet, "/snippets/s2", nil, "")
		if rec.Code != http.StatusOK {
			t.Fatalf("want 200, got %d", rec.Code)
		}
		m := decodeSnippetMap(t, rec.Body.Bytes())
		if len(m) != 3 {
			t.Fatalf("want exactly 3 keys, got %d: %v", len(m), m)
		}
		for _, k := range []string{"id", "title", "content"} {
			if _, ok := m[k]; !ok {
				t.Fatalf("missing key %q", k)
			}
		}
		if _, extra := m["user_id"]; extra {
			t.Fatal("response should not have user_id key")
		}
	})
}

// ---------- TestListSnippets ----------

func TestListSnippets(t *testing.T) {
	t.Run("only caller's snippets returned (seed two users)", func(t *testing.T) {
		h, store := setupSnippetHandler()
		_ = store.Create(nil, &models.Snippet{ID: "s1", Title: "a", Content: "1", UserID: "u1"})
		_ = store.Create(nil, &models.Snippet{ID: "s2", Title: "b", Content: "2", UserID: "u2"})
		_ = store.Create(nil, &models.Snippet{ID: "s3", Title: "c", Content: "3", UserID: "u1"})

		rec := doSnippetRequest(h.List, http.MethodGet, "/snippets", nil, "u1")
		if rec.Code != http.StatusOK {
			t.Fatalf("want 200, got %d", rec.Code)
		}
		var arr []map[string]any
		if err := json.Unmarshal(rec.Body.Bytes(), &arr); err != nil {
			t.Fatalf("body not valid JSON array: %v", err)
		}
		if len(arr) != 2 {
			t.Fatalf("want 2 snippets for u1, got %d", len(arr))
		}
		for _, item := range arr {
			if _, ok := item["user_id"]; ok {
				t.Fatal("list response should not have user_id key")
			}
		}
	})

	t.Run("no snippets -> body is literally []", func(t *testing.T) {
		h, _ := setupSnippetHandler()
		rec := doSnippetRequest(h.List, http.MethodGet, "/snippets", nil, "empty-user")
		if rec.Code != http.StatusOK {
			t.Fatalf("want 200, got %d", rec.Code)
		}
		raw := bytes.TrimSpace(rec.Body.Bytes())
		if string(raw) != "[]" {
			t.Fatalf("want literal [], got %q", string(raw))
		}
	})

	t.Run("unauthenticated -> 401", func(t *testing.T) {
		h, _ := setupSnippetHandler()
		rec := doSnippetRequest(h.List, http.MethodGet, "/snippets", nil, "")
		if rec.Code != http.StatusUnauthorized {
			t.Fatalf("want 401, got %d", rec.Code)
		}
		assertContentTypeJSON(t, rec)
	})

	t.Run("each element has exactly 3 keys", func(t *testing.T) {
		h, store := setupSnippetHandler()
		_ = store.Create(nil, &models.Snippet{ID: "s1", Title: "a", Content: "1", UserID: "u1"})

		rec := doSnippetRequest(h.List, http.MethodGet, "/snippets", nil, "u1")
		var arr []map[string]any
		if err := json.Unmarshal(rec.Body.Bytes(), &arr); err != nil {
			t.Fatalf("body not JSON array: %v", err)
		}
		if len(arr) != 1 {
			t.Fatalf("want 1, got %d", len(arr))
		}
		if len(arr[0]) != 3 {
			t.Fatalf("want 3 keys per element, got %d: %v", len(arr[0]), arr[0])
		}
	})
}

// ---------- TestDeleteSnippet ----------

func TestDeleteSnippet(t *testing.T) {
	t.Run("owner -> 204 empty body, snippet removed", func(t *testing.T) {
		h, store := setupSnippetHandler()
		_ = store.Create(nil, &models.Snippet{ID: "s1", Title: "t", Content: "c", UserID: "u1"})

		rec := doSnippetRequest(h.Delete, http.MethodDelete, "/snippets/s1", nil, "u1")
		if rec.Code != http.StatusNoContent {
			t.Fatalf("want 204, got %d (body=%s)", rec.Code, rec.Body.String())
		}
		if rec.Body.Len() != 0 {
			t.Fatalf("want empty body, got %q", rec.Body.String())
		}
		if store.HasSnippet("s1") {
			t.Fatal("snippet should be gone")
		}
	})

	t.Run("non-owner -> 403, snippet still present", func(t *testing.T) {
		h, store := setupSnippetHandler()
		_ = store.Create(nil, &models.Snippet{ID: "s1", Title: "t", Content: "c", UserID: "owner"})

		rec := doSnippetRequest(h.Delete, http.MethodDelete, "/snippets/s1", nil, "other")
		if rec.Code != http.StatusForbidden {
			t.Fatalf("want 403, got %d", rec.Code)
		}
		assertContentTypeJSON(t, rec)
		if !store.HasSnippet("s1") {
			t.Fatal("snippet should still exist")
		}
	})

	t.Run("nonexistent id -> 404", func(t *testing.T) {
		h, _ := setupSnippetHandler()
		rec := doSnippetRequest(h.Delete, http.MethodDelete, "/snippets/ghost", nil, "u1")
		if rec.Code != http.StatusNotFound {
			t.Fatalf("want 404, got %d", rec.Code)
		}
		assertContentTypeJSON(t, rec)
	})

	t.Run("unauthenticated -> 401", func(t *testing.T) {
		h, store := setupSnippetHandler()
		_ = store.Create(nil, &models.Snippet{ID: "s1", Title: "t", Content: "c", UserID: "owner"})
		rec := doSnippetRequest(h.Delete, http.MethodDelete, "/snippets/s1", nil, "")
		if rec.Code != http.StatusUnauthorized {
			t.Fatalf("want 401, got %d", rec.Code)
		}
		assertContentTypeJSON(t, rec)
	})

	t.Run("non-owner on nonexistent id -> 404 (not 403)", func(t *testing.T) {
		h, _ := setupSnippetHandler()
		rec := doSnippetRequest(h.Delete, http.MethodDelete, "/snippets/ghost", nil, "someone")
		if rec.Code != http.StatusNotFound {
			t.Fatalf("want 404, got %d", rec.Code)
		}
		assertContentTypeJSON(t, rec)
	})
}