package gateway

import (
	"context"
	"errors"
	"strings"
	"testing"

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

func TestParseTier(t *testing.T) {
	cases := []struct {
		in    string
		want  Tier
		known bool
	}{
		{"fast", TierFast, true},
		{"balanced", TierBalanced, true},
		{"deep", TierDeep, true},
		{"  DEEP  ", TierDeep, true},
		// Unset means the default, and is not a drift signal: most specs
		// simply do not declare a tier.
		{"", DefaultTier, true},
		// A tier that is not in the vocabulary still runs, at the default, but
		// reports itself so a drifted definition stays visible.
		{"thorough", DefaultTier, false},
	}
	for _, c := range cases {
		got, known := ParseTier(c.in)
		if got != c.want || known != c.known {
			t.Errorf("ParseTier(%q) = (%q, %v), want (%q, %v)", c.in, got, known, c.want, c.known)
		}
	}
}

func TestUsageTotalCountsCacheReads(t *testing.T) {
	// A cache read is cheaper than fresh input, not free. Excluding it would
	// make the budget drift further from the truth the longer a run went on.
	u := Usage{InputTokens: 100, OutputTokens: 50, CacheReadTokens: 900, CacheCreationTokens: 10}
	if got := u.Total(); got != 1060 {
		t.Errorf("Total() = %d, want 1060", got)
	}
}

func TestRequestValidate(t *testing.T) {
	if err := (Request{}).Validate(); err == nil {
		t.Error("a request with no messages should be refused")
	}

	blank := Request{Messages: []Message{{Role: RoleUser, Text: "   "}}}
	if err := blank.Validate(); err == nil {
		t.Error("a whitespace-only message should be refused")
	}

	bad := Request{Messages: []Message{{Role: "system", Text: "hi"}}}
	err := bad.Validate()
	var gwErr *Error
	if !errors.As(err, &gwErr) || gwErr.Code != CodeInvalidRequest {
		t.Errorf("a bad role should give CodeInvalidRequest, got %v", err)
	}

	ok := Request{Messages: []Message{{Role: RoleUser, Text: "which shifts are uncovered?"}}}
	if err := ok.Validate(); err != nil {
		t.Errorf("a valid request was refused: %v", err)
	}
}

func TestCompleteWithoutCredentialsIsStructured(t *testing.T) {
	// The service boots without a key on purpose. The failure has to arrive as
	// something a run can terminate with, not as a panic or a bare string.
	g := NewOpenAI(Config{})
	_, err := g.Complete(context.Background(), Request{
		Messages: []Message{{Role: RoleUser, Text: "anything"}},
	})

	var gwErr *Error
	if !errors.As(err, &gwErr) {
		t.Fatalf("want a *gateway.Error, got %T: %v", err, err)
	}
	if gwErr.Code != CodeNotConfigured {
		t.Errorf("Code = %q, want %q", gwErr.Code, CodeNotConfigured)
	}
	if gwErr.Retryable() {
		t.Error("a missing key is not fixed by retrying")
	}
}

func TestRetryable(t *testing.T) {
	cases := map[*Error]bool{
		{Code: CodeRateLimited}:               true,
		{Code: CodeTimeout}:                   true,
		{Code: CodeUpstream, Status: 503}:     true,
		{Code: CodeUpstream, Status: 400}:     false,
		{Code: CodeUnauthorized, Status: 401}: false,
		{Code: CodeInvalidRequest}:            false,
		// The one that matters: re-sending a request the model declined is how
		// a loop spends a whole budget on a single turn.
		{Code: CodeRefused, Category: "cyber"}: false,
	}
	for err, want := range cases {
		if got := err.Retryable(); got != want {
			t.Errorf("%s: Retryable() = %v, want %v", err.Code, got, want)
		}
	}
}

func TestFromConfigPinsEffortPerTier(t *testing.T) {
	cfg := FromConfig(config.ModelConfig{
		APIKey: "test", Fast: "m-fast", Balanced: "m-balanced", Deep: "m-deep",
		MaxOutputTokens: 8000,
	})

	if cfg.Fast.Effort != EffortLow {
		t.Errorf("fast effort = %q, want low", cfg.Fast.Effort)
	}
	if cfg.Balanced.Effort != EffortHigh {
		t.Errorf("balanced effort = %q, want high", cfg.Balanced.Effort)
	}
	if cfg.Deep.Effort != EffortXhigh {
		t.Errorf("deep effort = %q, want xhigh", cfg.Deep.Effort)
	}
	if cfg.MaxOutputTokens != 8000 {
		t.Errorf("MaxOutputTokens = %d, want 8000", cfg.MaxOutputTokens)
	}
}

// The neutral effort vocabulary still has to land on a vendor's own spelling,
// and that mapping is the one thing FromConfig cannot assert now that its
// result is provider-independent. Untested, a renamed constant would silently
// route every tier to whatever the default arm returns.
//
// This asserts POSITIONS, not words. OpenAI's scale runs minimal/low/medium/
// high against our low/high/xhigh, so `high` here is their "medium" — matching
// the spelling instead would collapse `fast` and `balanced` into neighbours.
func TestEffortMapsOntoTheProviderScale(t *testing.T) {
	cases := map[Effort]string{
		EffortLow:   "low",
		EffortHigh:  "medium",
		EffortXhigh: "high",
	}
	for neutral, want := range cases {
		if got := openAIEffort(neutral); got != want {
			t.Errorf("openAIEffort(%q) = %q, want %q", neutral, got, want)
		}
	}
}

func TestRoutingSelectsPerTier(t *testing.T) {
	g := NewOpenAI(Config{
		Fast:     Routing{Model: "m-fast"},
		Balanced: Routing{Model: "m-balanced"},
		Deep:     Routing{Model: "m-deep"},
	})

	cases := map[Tier]string{
		TierFast:     "m-fast",
		TierBalanced: "m-balanced",
		TierDeep:     "m-deep",
		// A zero value routes to balanced rather than to an empty model id.
		Tier(""): "m-balanced",
	}
	for tier, want := range cases {
		if got := g.routing(tier).Model; got != want {
			t.Errorf("routing(%q) = %q, want %q", tier, got, want)
		}
	}
}

/* ── Retrying what is worth retrying ────────────────────────────────────── */

func TestATransientOverloadIsWorthRetrying(t *testing.T) {
	// The classification this asserts existed from the start and had ZERO
	// callers, so a 529 killed runs that would have succeeded a moment later.
	// Found by a real overload during live testing.
	overloaded := &Error{Code: CodeUpstream, Message: "overloaded", Status: 529}
	if !overloaded.Retryable() {
		t.Error("a 529 overload should be retryable — it is the transient failure that actually happens")
	}

	for _, e := range []*Error{
		{Code: CodeRateLimited, Status: 429},
		{Code: CodeTimeout},
		{Code: CodeUpstream, Status: 503},
	} {
		if !e.Retryable() {
			t.Errorf("%s (status %d) should be retryable", e.Code, e.Status)
		}
	}

	// And the ones that will fail identically every time must not be.
	for _, e := range []*Error{
		{Code: CodeInvalidRequest, Status: 400},
		{Code: CodeUnauthorized, Status: 401},
		{Code: CodeNotConfigured},
		{Code: CodeRefused},
	} {
		if e.Retryable() {
			t.Errorf("%s should NOT be retryable — the same call will fail the same way", e.Code)
		}
	}
}

func TestAnUpstreamErrorNamesItsStatus(t *testing.T) {
	// "the model call failed" cost an hour of debugging, because the trajectory
	// records the message and the message did not say it was a 529. A failure
	// an operator cannot classify is a failure they cannot act on.
	e := &Error{
		Code:    CodeUpstream,
		Message: "the model call failed (http 529)",
		Status:  529,
	}
	if !strings.Contains(e.Error(), "529") {
		t.Errorf("the rendered error hides its status: %s", e.Error())
	}
}