package cast

import (
	"context"
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"sync/atomic"
	"testing"
)

func TestSendSMS_Success(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			t.Errorf("expected POST, got %s", r.Method)
		}
		if r.URL.Path != "/api/sms/send" {
			t.Errorf("expected /api/sms/send, got %s", r.URL.Path)
		}
		if r.Header.Get("X-API-Key") != "cast_testkey" {
			t.Errorf("expected X-API-Key cast_testkey, got %s", r.Header.Get("X-API-Key"))
		}
		var body SendRequest
		json.NewDecoder(r.Body).Decode(&body)
		if body.To != "09171234567" {
			t.Errorf("expected to=09171234567, got %s", body.To)
		}
		w.WriteHeader(http.StatusOK)
		json.NewEncoder(w).Encode(SendResponse{Success: true, MessageID: "abc123", Parts: 1})
	}))
	defer srv.Close()

	client := NewClient(srv.URL, "cast_testkey", "")
	resp, err := client.SendSMS(context.Background(), "09171234567", "test message")
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if !resp.Success || resp.MessageID != "abc123" {
		t.Errorf("unexpected response: %+v", resp)
	}
}

func TestSendSMS_APIError(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusPaymentRequired)
		json.NewEncoder(w).Encode(SendResponse{Success: false, Error: "insufficient credits"})
	}))
	defer srv.Close()

	client := NewClient(srv.URL, "cast_testkey", "")
	_, err := client.SendSMS(context.Background(), "09171234567", "test")
	if err == nil {
		t.Fatal("expected error, got nil")
	}
	castErr, ok := err.(*CastAPIError)
	if !ok {
		t.Fatalf("expected CastAPIError, got %T", err)
	}
	if castErr.StatusCode != http.StatusPaymentRequired {
		t.Errorf("expected 402, got %d", castErr.StatusCode)
	}
}

func TestSendSMS_SuccessFalseInBody(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusOK)
		json.NewEncoder(w).Encode(SendResponse{Success: false, Error: "invalid number"})
	}))
	defer srv.Close()

	client := NewClient(srv.URL, "cast_testkey", "")
	_, err := client.SendSMS(context.Background(), "09171234567", "test")
	if err == nil {
		t.Fatal("expected error, got nil")
	}
	castErr, ok := err.(*CastAPIError)
	if !ok {
		t.Fatalf("expected CastAPIError, got %T", err)
	}
	if castErr.APIError != "invalid number" {
		t.Errorf("expected 'invalid number', got %s", castErr.APIError)
	}
}

func TestSendSMS_WithSenderID(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		var body SendRequest
		json.NewDecoder(r.Body).Decode(&body)
		if body.SenderID != "CAST" {
			t.Errorf("expected sender_id=CAST, got %q", body.SenderID)
		}
		w.WriteHeader(http.StatusOK)
		json.NewEncoder(w).Encode(SendResponse{Success: true, MessageID: "x1", Parts: 1})
	}))
	defer srv.Close()

	client := NewClient(srv.URL, "cast_testkey", "CAST")
	_, err := client.SendSMS(context.Background(), "09171234567", "test")
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
}

func TestSendSMS_WithoutSenderID(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		var rawBody map[string]interface{}
		json.NewDecoder(r.Body).Decode(&rawBody)
		if _, ok := rawBody["sender_id"]; ok {
			t.Error("sender_id should be omitted when empty")
		}
		w.WriteHeader(http.StatusOK)
		json.NewEncoder(w).Encode(SendResponse{Success: true, MessageID: "x2", Parts: 1})
	}))
	defer srv.Close()

	client := NewClient(srv.URL, "cast_testkey", "")
	_, err := client.SendSMS(context.Background(), "09171234567", "test")
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
}

// TC5: Failed Cast API key — 401 response is returned as a CastAPIError.
func TestSendSMS_Unauthorized(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusUnauthorized)
		json.NewEncoder(w).Encode(SendResponse{Success: false, Error: "invalid api key"})
	}))
	defer srv.Close()

	client := NewClient(srv.URL, "cast_badkey", "")
	_, err := client.SendSMS(context.Background(), "09171234567", "test")
	if err == nil {
		t.Fatal("expected error for 401, got nil")
	}
	castErr, ok := err.(*CastAPIError)
	if !ok {
		t.Fatalf("expected CastAPIError, got %T: %v", err, err)
	}
	if castErr.StatusCode != http.StatusUnauthorized {
		t.Errorf("expected status 401, got %d", castErr.StatusCode)
	}
}

func TestSendSMS_RetryOn429(t *testing.T) {
	var callCount atomic.Int32
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		n := callCount.Add(1)
		if n <= 2 {
			w.Header().Set("Retry-After", "0")
			w.WriteHeader(http.StatusTooManyRequests)
			return
		}
		w.WriteHeader(http.StatusOK)
		json.NewEncoder(w).Encode(SendResponse{Success: true, MessageID: "retry-ok", Parts: 1})
	}))
	defer srv.Close()

	client := NewClient(srv.URL, "cast_testkey", "")
	resp, err := client.SendSMS(context.Background(), "09171234567", "test")
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if resp.MessageID != "retry-ok" {
		t.Errorf("expected retry-ok, got %s", resp.MessageID)
	}
	if callCount.Load() != 3 {
		t.Errorf("expected 3 calls, got %d", callCount.Load())
	}
}