package httpserver

// Unit tests for the wording a GatewayFailure produces.
//
// Internal rather than httpserver_test because the function under test is the
// mapping itself, and the mapping is unexported. Pure: no server, no database,
// no fixture — a cause goes in and a sentence comes out.
//
// What these assert is one property, and it is the one the old wording broke:
// a reader is told to retry EXACTLY when retrying can work. A rate limit clears
// on its own; a rejected credential, a model id the endpoint does not have, and
// an unconfigured deployment do not, and telling somebody to wait a minute for
// any of those is a loop with no exit.

import (
	"errors"
	"strings"
	"testing"

	"github.com/krow/krow-backend/go-api/internal/gateway"
	"github.com/krow/krow-backend/go-api/internal/runtime"
)

// invitesRetry reports whether a sentence tells the reader to try again.
//
// Deliberately looser than an equality check on the whole string: what must
// hold is the ADVICE, not the copy, so rewording a sentence does not fail a
// test that was never about the words.
func invitesRetry(message string) bool {
	m := strings.ToLower(message)
	return strings.Contains(m, "ask again") || strings.Contains(m, "try again")
}

func TestGatewayFailureMessageInvitesRetryOnlyWhenRetryingCanWork(t *testing.T) {
	cases := []struct {
		name  string
		cause error
		retry bool
	}{
		{
			name:  "a rate limit clears on its own",
			cause: &gateway.Error{Code: gateway.CodeRateLimited, Status: 429},
			retry: true,
		},
		{
			name:  "a provider 5xx is worth another attempt",
			cause: &gateway.Error{Code: gateway.CodeUpstream, Status: 503},
			retry: true,
		},
		{
			name:  "a rejected credential will be rejected again",
			cause: &gateway.Error{Code: gateway.CodeUnauthorized, Status: 401},
			retry: false,
		},
		{
			name:  "a model the endpoint does not have stays absent",
			cause: &gateway.Error{Code: gateway.CodeInvalidRequest, Status: 404},
			retry: false,
		},
		{
			name:  "an unconfigured deployment cannot answer at all",
			cause: &gateway.Error{Code: gateway.CodeNotConfigured},
			retry: false,
		},
	}

	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			got := gatewayFailureMessage(tc.cause)
			if got == "" {
				t.Fatal("a failed run must say something")
			}
			if invitesRetry(got) != tc.retry {
				t.Errorf("retry advice = %v, want %v\n  message: %q",
					invitesRetry(got), tc.retry, got)
			}
			// Nothing ran, so nothing can have been written. The reassurance is
			// the whole reason this termination is not frightening.
			if !strings.Contains(got, "Nothing was changed") {
				t.Errorf("message must say nothing was changed: %q", got)
			}
		})
	}
}

// The three that need a person are the three that used to be indistinguishable
// from load. Each must point at one, or the reader has no idea what to do next.
func TestGatewayFailureMessageNamesAnAdministratorWhenOneIsNeeded(t *testing.T) {
	for _, code := range []string{
		gateway.CodeUnauthorized,
		gateway.CodeInvalidRequest,
		gateway.CodeNotConfigured,
	} {
		got := gatewayFailureMessage(&gateway.Error{Code: code})
		if !strings.Contains(strings.ToLower(got), "administrator") {
			t.Errorf("%s: must send the reader to an administrator: %q", code, got)
		}
	}
}

// Vendor names, model ids and HTTP statuses are for the trajectory, not for a
// venue manager — they cannot act on any of them.
func TestGatewayFailureMessageLeaksNoOperatorDetail(t *testing.T) {
	for _, code := range []string{
		gateway.CodeRateLimited,
		gateway.CodeUpstream,
		gateway.CodeUnauthorized,
		gateway.CodeInvalidRequest,
		gateway.CodeNotConfigured,
	} {
		got := gatewayFailureMessage(&gateway.Error{
			Code:    code,
			Status:  429,
			Message: "gemini-3.5-flash-lite quota exceeded for project 12345",
		})
		for _, leak := range []string{"gemini", "429", "quota", "http", "12345"} {
			if strings.Contains(strings.ToLower(got), leak) {
				t.Errorf("%s: message carries operator detail %q: %q", code, leak, got)
			}
		}
	}
}

// A cause that is not a gateway error — lost, wrapped away, or a non-gateway
// failure that reached this termination — still has to produce a sentence.
func TestGatewayFailureMessageFallsBackWithoutAGatewayError(t *testing.T) {
	for _, cause := range []error{nil, errors.New("something else entirely")} {
		if got := gatewayFailureMessage(cause); got == "" {
			t.Errorf("cause %v produced no message", cause)
		}
	}
}

// The cause arrives wrapped in a RuntimeError, which is how the surface
// actually receives it. If Unwrap ever stopped reaching the gateway error,
// every failure would silently fall back to "usually it is busy" — the exact
// bug this change exists to fix, reintroduced without a compile error.
func TestGatewayFailureMessageReadsThroughARuntimeError(t *testing.T) {
	wrapped := &runtime.RuntimeError{
		Code:  "runtime.gatewayfailure",
		Cause: &gateway.Error{Code: gateway.CodeUnauthorized, Status: 401},
	}

	got := gatewayFailureMessage(wrapped)
	if invitesRetry(got) {
		t.Errorf("a wrapped credential failure must not invite a retry: %q", got)
	}
}

// The other terminations are unchanged by the new parameter: they ignore the
// cause, so passing one must not alter a single word.
func TestTerminationMessageIgnoresTheCauseElsewhere(t *testing.T) {
	cause := &gateway.Error{Code: gateway.CodeUnauthorized}

	for _, term := range []runtime.Termination{
		runtime.TerminationBudgetExceeded,
		runtime.TerminationDeadline,
		runtime.TerminationConfirmationPending,
		runtime.TerminationToolFailure,
		runtime.TerminationRefused,
	} {
		if terminationMessage(term, nil) != terminationMessage(term, cause) {
			t.Errorf("%s: wording changed with the cause", term)
		}
	}

	if terminationMessage(runtime.TerminationCompleted, nil) != "" {
		t.Error("a completed run has nothing to say")
	}
}