package backend_test

import (
	"errors"
	"strings"
	"testing"

	"gitea.maximumdirect.net/eric/promptkit/internal/backend"
	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
)

const validEndpoint = "https://backend.example/v1"

func TestRegistryIncludesExactOpenRouterDefinition(t *testing.T) {
	registry, err := backend.NewRegistry(nil)
	if err != nil {
		t.Fatalf("construct registry: %v", err)
	}

	definition, err := registry.GetBackend(backend.OpenRouterID)
	if err != nil {
		t.Fatalf("look up OpenRouter: %v", err)
	}
	if definition.ID != "openrouter" ||
		definition.Endpoint != "https://openrouter.ai/api/v1" ||
		definition.APIKeyEnv != "OPENROUTER_API_KEY" ||
		definition.ExtraParams != nil {
		t.Fatalf("unexpected OpenRouter definition: %#v", definition)
	}
}

func TestRegistryNormalizesUniqueAdditionsAndIsolatesMutations(t *testing.T) {
	nested := map[string]int{"limit": 2}
	extraParams := map[string]any{
		"count":  int64(7),
		"nested": nested,
	}
	registry, err := backend.NewRegistry([]domain.Backend{
		{
			ID:          " custom ",
			Endpoint:    " https://custom.example/openai/v1 ",
			APIKeyEnv:   " CUSTOM_API_KEY ",
			ExtraParams: extraParams,
		},
		{
			ID:       "Custom",
			Endpoint: validEndpoint,
		},
	})
	if err != nil {
		t.Fatalf("construct registry: %v", err)
	}

	nested["limit"] = 99
	extraParams["added"] = true

	got, err := registry.GetBackend("custom")
	if err != nil {
		t.Fatalf("look up custom backend: %v", err)
	}
	if got.ID != "custom" ||
		got.Endpoint != "https://custom.example/openai/v1" ||
		got.APIKeyEnv != "CUSTOM_API_KEY" {
		t.Fatalf("unexpected normalized definition: %#v", got)
	}
	if count, ok := got.ExtraParams["count"].(int64); !ok || count != 7 {
		t.Fatalf("integer type or value changed: %#v", got.ExtraParams["count"])
	}
	gotNested, ok := got.ExtraParams["nested"].(map[string]int)
	if !ok || gotNested["limit"] != 2 {
		t.Fatalf("container type or value changed: %#v", got.ExtraParams["nested"])
	}
	if _, exists := got.ExtraParams["added"]; exists {
		t.Fatalf("registry retained caller map: %#v", got.ExtraParams)
	}

	gotNested["limit"] = 100
	got.ExtraParams["added"] = true
	again, err := registry.GetBackend("custom")
	if err != nil {
		t.Fatalf("look up custom backend again: %v", err)
	}
	if again.ExtraParams["nested"].(map[string]int)["limit"] != 2 {
		t.Fatalf("lookup exposed registry nested map: %#v", again.ExtraParams)
	}
	if _, exists := again.ExtraParams["added"]; exists {
		t.Fatalf("lookup exposed registry map: %#v", again.ExtraParams)
	}

	if _, err := registry.GetBackend("Custom"); err != nil {
		t.Fatalf("backend IDs should be case-sensitive: %v", err)
	}
}

func TestNewRegistryRejectsDuplicateIDs(t *testing.T) {
	tests := []struct {
		name      string
		additions []domain.Backend
		wantID    string
	}{
		{
			name: "built-in collision after normalization",
			additions: []domain.Backend{{
				ID: " openrouter ",
			}},
			wantID: "openrouter",
		},
		{
			name: "consumer collision after normalization",
			additions: []domain.Backend{
				{ID: "custom", Endpoint: validEndpoint},
				{ID: " custom ", Endpoint: "https://other.example/v1"},
			},
			wantID: "custom",
		},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			_, err := backend.NewRegistry(tc.additions)
			if err == nil {
				t.Fatal("expected duplicate ID error")
			}
			if !strings.Contains(err.Error(), tc.wantID) {
				t.Fatalf("expected error to identify %q, got %v", tc.wantID, err)
			}
		})
	}
}

func TestNewRegistryValidatesIDs(t *testing.T) {
	for _, id := range []string{"", " \t\n "} {
		t.Run(id, func(t *testing.T) {
			_, err := backend.NewRegistry([]domain.Backend{{
				ID:       id,
				Endpoint: validEndpoint,
			}})
			if err == nil {
				t.Fatal("expected blank ID error")
			}
		})
	}
}

func TestNewRegistryValidatesEndpoints(t *testing.T) {
	tests := []struct {
		name     string
		endpoint string
	}{
		{name: "blank", endpoint: ""},
		{name: "relative", endpoint: "/v1"},
		{name: "missing host", endpoint: "https:///v1"},
		{name: "unsupported scheme", endpoint: "ftp://backend.example/v1"},
		{name: "user information", endpoint: "https://user@backend.example/v1"},
		{name: "query", endpoint: "https://backend.example/v1?mode=chat"},
		{name: "empty query", endpoint: "https://backend.example/v1?"},
		{name: "fragment", endpoint: "https://backend.example/v1#chat"},
		{name: "empty fragment", endpoint: "https://backend.example/v1#"},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			_, err := backend.NewRegistry([]domain.Backend{{
				ID:       "custom",
				Endpoint: tc.endpoint,
			}})
			if err == nil {
				t.Fatal("expected invalid endpoint error")
			}
		})
	}
}

func TestNewRegistryValidatesEnvironmentVariableNames(t *testing.T) {
	for _, name := range []string{"1API_KEY", "API-KEY", "API KEY", "ÅPI_KEY"} {
		t.Run(name, func(t *testing.T) {
			_, err := backend.NewRegistry([]domain.Backend{{
				ID:        "custom",
				Endpoint:  validEndpoint,
				APIKeyEnv: name,
			}})
			if err == nil {
				t.Fatal("expected invalid environment-variable name error")
			}
		})
	}
}

func TestNewRegistryRejectsInvalidAndReservedExtraParameters(t *testing.T) {
	tests := []struct {
		name        string
		extraParams map[string]any
	}{
		{name: "unsupported value", extraParams: map[string]any{"value": make(chan int)}},
		{name: "reserved key", extraParams: map[string]any{"model": "override"}},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			_, err := backend.NewRegistry([]domain.Backend{{
				ID:          "custom",
				Endpoint:    validEndpoint,
				ExtraParams: tc.extraParams,
			}})
			if err == nil {
				t.Fatal("expected invalid extra parameters error")
			}
		})
	}
}

func TestRegistryLookupReportsNotFound(t *testing.T) {
	registry, err := backend.NewRegistry(nil)
	if err != nil {
		t.Fatalf("construct registry: %v", err)
	}

	_, err = registry.GetBackend("missing")
	if !errors.Is(err, backend.ErrBackendNotFound) {
		t.Fatalf("expected ErrBackendNotFound, got %v", err)
	}
	if !strings.Contains(err.Error(), "missing") {
		t.Fatalf("expected error to identify backend, got %v", err)
	}
}