package bot

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

	"github.com/go-telegram/bot/models"
	"go.uber.org/zap"
)

const testChatID = 555

// chatAPI is a fake Bot API for the chat-gating tests: it answers getMe, returns a
// scripted getChatMember status, and records restrictChatMember calls.
type chatAPI struct {
	memberStatus string // the status getChatMember reports (default "left")
	restricts    []restrictCall
}

type restrictCall struct {
	userID  string
	canSend bool // can_send_messages in the applied permissions
}

func (a *chatAPI) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	switch {
	case strings.HasSuffix(r.URL.Path, "/getMe"):
		io.WriteString(w, `{"ok":true,"result":{"id":1,"is_bot":true,"first_name":"t","username":"tb"}}`)
	case strings.HasSuffix(r.URL.Path, "/getChatMember"):
		status := a.memberStatus
		if status == "" {
			status = "left"
		}
		io.WriteString(w, `{"ok":true,"result":{"status":"`+status+`","user":{"id":`+r.FormValue("user_id")+`,"is_bot":false,"first_name":"u"}}}`)
	case strings.HasSuffix(r.URL.Path, "/restrictChatMember"):
		var perms struct {
			CanSendMessages bool `json:"can_send_messages"`
		}
		_ = json.Unmarshal([]byte(r.FormValue("permissions")), &perms)
		a.restricts = append(a.restricts, restrictCall{userID: r.FormValue("user_id"), canSend: perms.CanSendMessages})
		io.WriteString(w, `{"ok":true,"result":true}`)
	default:
		io.WriteString(w, `{"ok":true,"result":true}`)
	}
}

// newChatBot builds a gating bot (ChatID set) over the fake API, without an
// eligibility resolver — each test wires the one it needs.
func newChatBot(t *testing.T, api *chatAPI) *Bot {
	t.Helper()
	srv := httptest.NewServer(api)
	t.Cleanup(srv.Close)
	b, err := New(Config{Token: "123:ABC", APIBaseURL: srv.URL, MiniAppURL: "https://example.com/", ChatID: testChatID}, zap.NewNop())
	if err != nil {
		t.Fatalf("new bot: %v", err)
	}
	return b
}

// memberUpdate builds an oldType -> member transition for userID in chatID.
func memberUpdate(chatID, userID int64, oldType models.ChatMemberType) *models.ChatMemberUpdated {
	return &models.ChatMemberUpdated{
		Chat:          models.Chat{ID: chatID},
		OldChatMember: models.ChatMember{Type: oldType, Left: &models.ChatMemberLeft{User: &models.User{ID: userID}}},
		NewChatMember: models.ChatMember{Type: models.ChatMemberTypeMember, Member: &models.ChatMemberMember{User: &models.User{ID: userID}}},
	}
}

// restrictedUpdate builds an oldType -> restricted transition for userID, the new
// member's text-send permission set to canSend. A default-deny group reports a present
// member as restricted with canSend=false.
func restrictedUpdate(chatID, userID int64, oldType models.ChatMemberType, canSend bool) *models.ChatMemberUpdated {
	return &models.ChatMemberUpdated{
		Chat:          models.Chat{ID: chatID},
		OldChatMember: models.ChatMember{Type: oldType, Left: &models.ChatMemberLeft{User: &models.User{ID: userID}}},
		NewChatMember: models.ChatMember{Type: models.ChatMemberTypeRestricted, Restricted: &models.ChatMemberRestricted{User: &models.User{ID: userID}, CanSendMessages: canSend}},
	}
}

// leftUpdate builds a transition to left (a leave) for userID.
func leftUpdate(chatID, userID int64) *models.ChatMemberUpdated {
	return &models.ChatMemberUpdated{
		Chat:          models.Chat{ID: chatID},
		OldChatMember: models.ChatMember{Type: models.ChatMemberTypeRestricted, Restricted: &models.ChatMemberRestricted{User: &models.User{ID: userID}}},
		NewChatMember: models.ChatMember{Type: models.ChatMemberTypeLeft, Left: &models.ChatMemberLeft{User: &models.User{ID: userID}}},
	}
}

// eligibleBot builds a gating bot whose resolver returns (eligible, err).
func eligibleBot(t *testing.T, api *chatAPI, eligible bool, err error) *Bot {
	t.Helper()
	b := newChatBot(t, api)
	b.SetEligibilityResolver(func(context.Context, string) (bool, error) { return eligible, err })
	return b
}

func TestHandleChatMemberGrantsEligibleMemberJoin(t *testing.T) {
	api := &chatAPI{}
	b := eligibleBot(t, api, true, nil)
	b.handleChatMember(context.Background(), memberUpdate(testChatID, 777, models.ChatMemberTypeLeft))
	if len(api.restricts) != 1 || api.restricts[0].userID != "777" || !api.restricts[0].canSend {
		t.Fatalf("restricts = %+v, want one grant (can_send=true) for 777", api.restricts)
	}
}

func TestHandleChatMemberGrantsRestrictedMember(t *testing.T) {
	// A default-deny group reports a present member as restricted with no send right —
	// the real-world case. Both a fresh join (left->restricted) and an already-present
	// restricted member (restricted->restricted) must be granted when eligible.
	for _, oldType := range []models.ChatMemberType{models.ChatMemberTypeLeft, models.ChatMemberTypeRestricted} {
		t.Run(string(oldType), func(t *testing.T) {
			api := &chatAPI{}
			b := eligibleBot(t, api, true, nil)
			b.handleChatMember(context.Background(), restrictedUpdate(testChatID, 777, oldType, false))
			if len(api.restricts) != 1 || !api.restricts[0].canSend {
				t.Fatalf("restricts = %+v, want one grant for a restricted member", api.restricts)
			}
		})
	}
}

func TestHandleChatMemberSkipsAlreadyAllowed(t *testing.T) {
	// The bot's own grant re-fires a chat_member event (restricted, can_send=true); it
	// must not loop into another grant.
	api := &chatAPI{}
	b := eligibleBot(t, api, true, nil)
	b.handleChatMember(context.Background(), restrictedUpdate(testChatID, 777, models.ChatMemberTypeRestricted, true))
	if len(api.restricts) != 0 {
		t.Fatalf("restricts = %+v, want none for an already-allowed member (no loop)", api.restricts)
	}
}

func TestHandleChatMemberSkipsIneligible(t *testing.T) {
	api := &chatAPI{}
	b := eligibleBot(t, api, false, nil)
	b.handleChatMember(context.Background(), restrictedUpdate(testChatID, 777, models.ChatMemberTypeLeft, false))
	if len(api.restricts) != 0 {
		t.Fatalf("an ineligible member was granted: %+v (want left muted)", api.restricts)
	}
}

func TestHandleChatMemberFailsClosedOnResolveError(t *testing.T) {
	api := &chatAPI{}
	b := eligibleBot(t, api, true, context.DeadlineExceeded)
	b.handleChatMember(context.Background(), restrictedUpdate(testChatID, 777, models.ChatMemberTypeLeft, false))
	if len(api.restricts) != 0 {
		t.Fatalf("a resolve error still granted write: %+v (want fail-closed)", api.restricts)
	}
}

func TestHandleChatMemberIgnoresOtherChatAndLeaves(t *testing.T) {
	api := &chatAPI{}
	b := eligibleBot(t, api, true, nil)
	ctx := context.Background()
	b.handleChatMember(ctx, restrictedUpdate(999, 777, models.ChatMemberTypeLeft, false)) // foreign chat
	b.handleChatMember(ctx, leftUpdate(testChatID, 777))                                  // a leave
	if len(api.restricts) != 0 {
		t.Fatalf("restricts = %+v, want none for a foreign chat / a leave", api.restricts)
	}
}

func TestApplyChatGatePresentMember(t *testing.T) {
	for _, tc := range []struct {
		name  string
		allow bool
	}{{"grant", true}, {"mute", false}} {
		t.Run(tc.name, func(t *testing.T) {
			api := &chatAPI{memberStatus: "member"}
			b := newChatBot(t, api)
			applied, err := b.ApplyChatGate(context.Background(), 777, tc.allow)
			if err != nil {
				t.Fatalf("apply: %v", err)
			}
			if !applied {
				t.Fatal("applied = false, want true for a present member")
			}
			if len(api.restricts) != 1 || api.restricts[0].canSend != tc.allow {
				t.Fatalf("restricts = %+v, want one with can_send=%v", api.restricts, tc.allow)
			}
		})
	}
}

func TestApplyChatGateSkipsAbsentAndAdmin(t *testing.T) {
	for _, status := range []string{"left", "kicked", "administrator", "creator"} {
		t.Run(status, func(t *testing.T) {
			api := &chatAPI{memberStatus: status}
			b := newChatBot(t, api)
			applied, err := b.ApplyChatGate(context.Background(), 777, false)
			if err != nil {
				t.Fatalf("apply: %v", err)
			}
			if applied {
				t.Errorf("applied = true for status %q, want a no-op", status)
			}
			if len(api.restricts) != 0 {
				t.Errorf("restricts = %+v for status %q, want none", api.restricts, status)
			}
		})
	}
}