package sms

import (
	"io"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
	"time"
)

// The gateway that closes the sign-in blocker.
//
// sms.Register had no callers anywhere in the tree, so logSender was never
// replaced and every customer verification code went to the application log
// instead of to a phone. That is why nobody could sign in, why the app's
// offline dev mode became the only practical way in, and why bookings "made"
// in that mode never reached the admin console.

func restoreSender(t *testing.T) {
	t.Helper()
	previous := active
	t.Cleanup(func() { active = previous })
}

func testSender(url, bodyTmpl string) httpSender {
	if bodyTmpl == "" {
		bodyTmpl = `{"to":"{{phone}}","message":"{{message}}","sender":"{{sender}}"}`
	}
	return httpSender{
		url:         url,
		method:      http.MethodPost,
		bodyTmpl:    bodyTmpl,
		contentType: "application/json",
		senderID:    "DRMILE",
		client:      &http.Client{Timeout: 5 * time.Second},
	}
}

// The destination and the code have to actually reach the gateway.
func TestGatewaySendsPhoneAndCode(t *testing.T) {
	var got string
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		b, _ := io.ReadAll(r.Body)
		got = string(b)
		w.WriteHeader(http.StatusOK)
	}))
	defer srv.Close()

	restoreSender(t)
	Register(testSender(srv.URL, ""))

	if err := SendOTP("+919876543210", "4821"); err != nil {
		t.Fatalf("SendOTP: %v", err)
	}
	for _, want := range []string{"+919876543210", "4821", "DRMILE"} {
		if !strings.Contains(got, want) {
			t.Errorf("gateway body %q is missing %q", got, want)
		}
	}
}

// A refused send — no balance, unapproved DLT template — must surface as an
// error. Swallowing it tells the customer a code is on its way when it is not,
// which is precisely the failure logSender has been producing all along.
func TestGatewayRefusalIsReported(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusPaymentRequired)
		_, _ = w.Write([]byte(`{"error":"insufficient balance"}`))
	}))
	defer srv.Close()

	restoreSender(t)
	Register(testSender(srv.URL, ""))

	if err := SendOTP("+919876543210", "4821"); err == nil {
		t.Error("a rejected send reported success — the customer would wait for a " +
			"text that is never coming")
	}
}

// An unreachable gateway is an error, not a silent no-op.
func TestUnreachableGatewayIsReported(t *testing.T) {
	restoreSender(t)
	Register(testSender("http://127.0.0.1:1/unreachable", ""))

	if err := SendOTP("+919876543210", "4821"); err == nil {
		t.Error("an unreachable gateway reported success")
	}
}

// A quote in the message must not break a JSON body template.
func TestMessageIsEscapedForJSON(t *testing.T) {
	var got string
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		b, _ := io.ReadAll(r.Body)
		got = string(b)
		w.WriteHeader(http.StatusOK)
	}))
	defer srv.Close()

	restoreSender(t)
	Register(testSender(srv.URL, ""))

	if err := active.Send("+919876543210", `say "hello"`); err != nil {
		t.Fatalf("send: %v", err)
	}
	if strings.Contains(got, `say "hello"`) {
		t.Errorf("an unescaped quote reached the JSON body: %q", got)
	}
	if !strings.Contains(got, `say \"hello\"`) {
		t.Errorf("the message was not escaped as expected: %q", got)
	}
}

// Vendors differ; the template is what makes one sender cover all of them.
func TestBodyTemplateIsVendorAgnostic(t *testing.T) {
	var got string
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		b, _ := io.ReadAll(r.Body)
		got = string(b)
		w.WriteHeader(http.StatusOK)
	}))
	defer srv.Close()

	restoreSender(t)
	Register(testSender(srv.URL, "mobiles={{phone}}&message={{message}}&sender={{sender}}"))

	if err := SendOTP("+919876543210", "4821"); err != nil {
		t.Fatalf("send: %v", err)
	}
	if !strings.HasPrefix(got, "mobiles=+919876543210&message=") {
		t.Errorf("form-encoded template not honoured: %q", got)
	}
}

// Configure is what gives sms.Register its first caller. With no URL it must
// leave the log sink exactly where it is, so this change cannot break a
// deployment that has not been configured yet.
func TestConfigureLeavesTheLogSinkWhenUnset(t *testing.T) {
	restoreSender(t)
	active = logSender{}
	setEnv(t, "SMS_GATEWAY_URL", "")

	Configure()

	if Configured() {
		t.Error("Configure installed a gateway with no SMS_GATEWAY_URL set")
	}
	if Transport() != "log" {
		t.Errorf("Transport() = %q, want \"log\"", Transport())
	}
}

func TestConfigureInstallsTheGatewayWhenSet(t *testing.T) {
	restoreSender(t)
	active = logSender{}
	setEnv(t, "SMS_GATEWAY_URL", "https://sms.example.invalid/send")

	Configure()

	if !Configured() {
		t.Fatal("Configure did not install a gateway despite SMS_GATEWAY_URL being set")
	}
	if Transport() != "http-gateway" {
		t.Errorf("Transport() = %q, want \"http-gateway\"", Transport())
	}
}

// In production the log sink must refuse rather than write a live credential
// to the log and report success.
func TestLogSenderRefusesInProduction(t *testing.T) {
	restoreSender(t)
	active = logSender{}

	setEnv(t, "ENV", "production")
	if err := SendOTP("+919876543210", "4821"); err == nil {
		t.Error("with no gateway in production, SendOTP reported success — the code " +
			"went to the log and the customer was told it was sent")
	}

	setEnv(t, "ENV", "development")
	if err := SendOTP("+919876543210", "4821"); err != nil {
		t.Errorf("outside production the log sink must still work for QA: %v", err)
	}
}