package gateway

import (
	"context"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
)

// TestComposeImageEndpoint_NoVersionBaseLeavesDefault is the counterpart of the
// /v1 case: when the base carries no version segment, discovery must emit "" so
// the gateway's own default "/v1/images/generations" composes.
//
// This is the shape every currently-working source uses — siliconflow, the only
// source in production with kind:image, has base_url
// "https://api.siliconflow.cn" — so writing a non-empty value here would break
// exactly the configuration that is known to work today.
func TestComposeImageEndpoint_NoVersionBaseLeavesDefault(t *testing.T) {
	if got := composeImageEndpoint("https://api.siliconflow.cn"); got != "" {
		t.Errorf("composeImageEndpoint = %q, want \"\" so the built-in default composes", got)
	}
	// And the composition it implies must be the vendor's real path.
	base := "https://api.siliconflow.cn"
	composed := base + "/v1/images/generations"
	if !strings.HasSuffix(composed, "/v1/images/generations") {
		t.Errorf("composed URL %q lost the image path", composed)
	}
}

// TestDiscovery_BareHostNeedsVersionOnEndpointWhenCatalogIsVersioned
// distinguishes two cases that look identical from the outside.
//
//	bare host + catalog at "/models"       → chat is "/chat/completions" (the
//	  adapter default, no endpoint written)
//	bare host + catalog at "/v1/models"    → chat is "/v1/chat/completions",
//	  so an endpoint MUST be written
//
// The catalog path is the only evidence of whether the upstream wants the
// version segment, and getting this backwards sends every chat request to a
// path the vendor does not serve.
func TestDiscovery_BareHostNeedsVersionOnEndpointWhenCatalogIsVersioned(t *testing.T) {
	cases := []struct {
		name         string
		catalogPath  string
		wantEndpoint string
		wantImage    string
	}{
		{
			name:         "catalog at the bare /models needs no endpoint",
			catalogPath:  "/models",
			wantEndpoint: "",
			wantImage:    "",
		},
		{
			name:         "catalog at /v1/models requires /v1 on the chat endpoint",
			catalogPath:  "/v1/models",
			wantEndpoint: "/v1/chat/completions",
			wantImage:    "",
		},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
				if r.URL.Path != tc.catalogPath {
					w.WriteHeader(http.StatusNotFound)
					return
				}
				_, _ = w.Write([]byte(`{"data":[{"id":"m1"},{"id":"m2"}]}`))
			}))
			defer srv.Close()

			res, err := DiscoverModels(context.Background(), srv.URL, "k")
			if err != nil {
				t.Fatalf("discovery failed: %v", err)
			}
			if res.BaseURL != srv.URL {
				t.Errorf("base = %q, want %q", res.BaseURL, srv.URL)
			}
			if res.Endpoint != tc.wantEndpoint {
				t.Errorf("endpoint = %q, want %q", res.Endpoint, tc.wantEndpoint)
			}
			if res.ImageEndpoint != tc.wantImage {
				t.Errorf("image_endpoint = %q, want %q", res.ImageEndpoint, tc.wantImage)
			}
			// Whatever it wrote, the chat URL must reach the same version
			// prefix the catalog was served under.
			ep := res.Endpoint
			if ep == "" {
				ep = "/chat/completions"
			}
			if got := res.BaseURL + ep; strings.Contains(got, "/v1/v1") {
				t.Errorf("chat URL %q has a doubled version", got)
			}
		})
	}
}

// TestComposeEndpoints_BothFormsProduceWorkingURLs is the end-to-end
// invariant across the two shapes, stated as the URLs the gateway will build.
//
// A base with a version and no image_endpoint produces "/v1/v1/…" — the exact
// 404 observed before composeImageEndpoint existed. A base without one and a
// non-empty image_endpoint produces a path missing the version. Both are
// silent, expensive mistakes, so they are asserted literally.
func TestComposeEndpoints_BothFormsProduceWorkingURLs(t *testing.T) {
	cases := []struct {
		name      string
		base      string
		wantChat  string
		wantImage string
	}{
		{
			name:     "bare host: adapter and image defaults compose",
			base:     "https://h",
			wantChat: "https://h/chat/completions",
			// openai's adapter endpoint is /chat/completions (verified in
			// internal/lua/adapters/openai.lua: adapter.endpoint).
			wantImage: "https://h/v1/images/generations",
		},
		{
			name:      "versioned base: the version moves onto both endpoints",
			base:      "https://h/v1",
			wantChat:  "https://h/v1/chat/completions",
			wantImage: "https://h/v1/images/generations",
		},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			ep := composeEndpoint("/models", tc.base, tc.base)
			if ep == "" {
				ep = "/chat/completions" // the adapter default
			}
			iep := composeImageEndpoint(tc.base)
			if iep == "" {
				iep = "/v1/images/generations" // the gateway default
			}
			gotChat := tc.base + ep
			gotImage := tc.base + iep
			if gotChat != tc.wantChat {
				t.Errorf("chat URL = %q, want %q", gotChat, tc.wantChat)
			}
			if gotImage != tc.wantImage {
				t.Errorf("image URL = %q, want %q", gotImage, tc.wantImage)
			}
			for _, u := range []string{gotChat, gotImage} {
				if strings.Contains(u, "/v1/v1") {
					t.Errorf("%q has a doubled version segment", u)
				}
			}
		})
	}
}