package service

import (
	"context"
	"encoding/json"
	"io"
	"net/http"
	"strings"
	"sync"
	"sync/atomic"
	"testing"
	"time"

	infraerrors "github.com/Wei-Shaw/sub2api/internal/pkg/errors"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

func ordinaryModelsUpstreamResponse(body string) *http.Response {
	return &http.Response{StatusCode: http.StatusOK, Header: make(http.Header), Body: io.NopCloser(strings.NewReader(body))}
}

func TestFetchOpenAIModelsListUsesStandardRequestAndIsolatesCodexCache(t *testing.T) {
	var calls atomic.Int32
	s := newCodexModelsAPIKeyTestService(&codexModelsHTTPUpstreamStub{do: func(req *http.Request, _ string, accountID int64, concurrency int) (*http.Response, error) {
		calls.Add(1)
		assert.EqualValues(t, 2, accountID)
		assert.EqualValues(t, 3, concurrency)
		assert.Equal(t, "/v1/models", req.URL.Path)
		assert.Equal(t, "value", getHeaderRaw(req.Header, "x-account-header"))
		if req.URL.Query().Has("client_version") {
			return ordinaryModelsUpstreamResponse(`{"models":[{"slug":"codex-only"}]}`), nil
		}
		assert.Empty(t, req.Header.Get("Originator"))
		assert.Empty(t, req.Header.Get("Version"))
		return ordinaryModelsUpstreamResponse(`{"object":"list","data":[{"id":"special-upstream-model","owned_by":"provider","created":1234,"custom":true},{"id":"gpt-image-1"},{"id":"text-embedding-3-large"}]}`), nil
	}})
	account := newCodexModelsAPIKeyTestAccount("https://models.example/v1")
	account.Credentials["header_overrides"] = map[string]any{"X-Account-Header": "value"}
	account.Credentials["header_override_enabled"] = true
	response, err := s.FetchOpenAIModelsList(context.Background(), account)
	require.NoError(t, err)
	require.Contains(t, string(response.Body), `"id":"gpt-image-1"`)
	require.Contains(t, string(response.Body), `"id":"text-embedding-3-large"`)
	require.Contains(t, string(response.Body), `"created":1234`)
	require.Contains(t, string(response.Body), `"custom":true`)
	manifest, err := s.FetchCodexModelsManifest(context.Background(), account, CodexCanonicalClientVersion(), "")
	require.NoError(t, err)
	require.Contains(t, string(manifest.Body), `"slug":"codex-only"`)
	again, err := s.FetchOpenAIModelsList(context.Background(), account)
	require.NoError(t, err)
	require.Equal(t, string(response.Body), string(again.Body))
	require.EqualValues(t, 2, calls.Load())
	account.Credentials["api_key"] = "rotated-token"
	_, err = s.FetchOpenAIModelsList(context.Background(), account)
	require.NoError(t, err)
	require.EqualValues(t, 3, calls.Load(), "credentials must participate in the cache key")
}

func TestFetchOpenAIModelsListOAuthSharesManifestCache(t *testing.T) {
	_, calls := newCodexModelsOAuthCacheServer(t, `{"models":[{"slug":"special-oauth-model"},{"slug":"gpt-image-1"}]}`)
	s := &OpenAIGatewayService{}
	account := newCodexModelsTestAccount()
	response, err := s.FetchOpenAIModelsList(context.Background(), account)
	require.NoError(t, err)
	require.JSONEq(t, `{"object":"list","data":[{"id":"special-oauth-model","object":"model","owned_by":"openai","created":0},{"id":"gpt-image-1","object":"model","owned_by":"openai","created":0}]}`, string(response.Body))
	manifest, err := s.FetchCodexModelsManifest(context.Background(), account, CodexCanonicalClientVersion(), "")
	require.NoError(t, err)
	require.Contains(t, string(manifest.Body), `"slug":"special-oauth-model"`)
	require.NotContains(t, string(manifest.Body), `"data"`)
	require.EqualValues(t, 1, calls.Load())
	_, err = s.FetchOpenAIModelsList(context.Background(), account)
	require.NoError(t, err)
	require.EqualValues(t, 1, calls.Load())
}

func TestFetchOpenAIModelsListCacheWindowsAndSingleflight(t *testing.T) {
	var calls atomic.Int32
	started := make(chan int32, 3)
	release := make(chan struct{}, 3)
	t.Cleanup(func() { close(release) })
	s := newCodexModelsAPIKeyTestService(&codexModelsHTTPUpstreamStub{do: func(_ *http.Request, _ string, _ int64, _ int) (*http.Response, error) {
		call := calls.Add(1)
		if call > 1 && call < 4 {
			started <- call
			<-release
		}
		if call >= 4 {
			response := ordinaryModelsUpstreamResponse(`{"error":"unavailable"}`)
			response.StatusCode = http.StatusServiceUnavailable
			return response, nil
		}
		return ordinaryModelsUpstreamResponse(`{"data":[{"id":"version-` + string(rune('0'+call)) + `"}]}`), nil
	}})
	account := newCodexModelsAPIKeyTestAccount("https://models.example/v1")
	first, err := s.FetchOpenAIModelsList(context.Background(), account)
	require.NoError(t, err)
	for range 5 {
		_, err = s.FetchOpenAIModelsList(context.Background(), account)
		require.NoError(t, err)
	}
	require.EqualValues(t, 1, calls.Load())
	expireCodexModelsManifestCache(s, 2*time.Minute)
	stale, err := s.FetchOpenAIModelsList(context.Background(), account)
	require.NoError(t, err)
	require.Equal(t, string(first.Body), string(stale.Body))
	select {
	case call := <-started:
		require.EqualValues(t, 2, call)
	case <-time.After(2 * time.Second):
		t.Fatal("stale response did not start a background refresh")
	}
	for range 5 {
		cached, err := s.FetchOpenAIModelsList(context.Background(), account)
		require.NoError(t, err)
		require.Equal(t, string(first.Body), string(cached.Body))
	}
	require.EqualValues(t, 2, calls.Load(), "concurrent stale reads must share the refresh")
	release <- struct{}{}
	require.Eventually(t, func() bool {
		s.openAIModelsCache.mu.Lock()
		defer s.openAIModelsCache.mu.Unlock()
		for _, entry := range s.openAIModelsCache.entries {
			if strings.Contains(string(entry.manifest.Body), "version-2") {
				return true
			}
		}
		return false
	}, 2*time.Second, time.Millisecond)

	expireCodexModelsManifestCache(s, 6*time.Minute)
	responses := make(chan *OpenAIModelsResponse, 2)
	fetchErrors := make(chan error, 2)
	var wait sync.WaitGroup
	for range 2 {
		wait.Add(1)
		go func() {
			defer wait.Done()
			response, err := s.FetchOpenAIModelsList(context.Background(), account)
			responses <- response
			fetchErrors <- err
		}()
	}
	select {
	case call := <-started:
		require.EqualValues(t, 3, call)
	case <-time.After(2 * time.Second):
		t.Fatal("expired catalog did not start a synchronous refresh")
	}
	select {
	case <-responses:
		t.Fatal("expired catalog returned before the upstream refresh completed")
	case <-time.After(20 * time.Millisecond):
	}
	release <- struct{}{}
	wait.Wait()
	for range 2 {
		require.NoError(t, <-fetchErrors)
		require.Contains(t, string((<-responses).Body), "version-3")
	}
	require.EqualValues(t, 3, calls.Load())
	expireCodexModelsManifestCache(s, 6*time.Minute)
	response, err := s.FetchOpenAIModelsList(context.Background(), account)
	require.Error(t, err)
	require.Nil(t, response)
	require.Equal(t, http.StatusBadGateway, infraerrors.Code(err))
}

func TestFetchOpenAIModelsListRevalidatesUpstreamETag(t *testing.T) {
	var calls atomic.Int32
	s := newCodexModelsAPIKeyTestService(&codexModelsHTTPUpstreamStub{do: func(req *http.Request, _ string, _ int64, _ int) (*http.Response, error) {
		response := ordinaryModelsUpstreamResponse(`{"data":[{"id":"unchanged"}]}`)
		response.Header.Set("ETag", `"upstream"`)
		if calls.Add(1) > 1 {
			assert.Equal(t, `"upstream"`, req.Header.Get("If-None-Match"))
			response.StatusCode = http.StatusNotModified
		}
		return response, nil
	}})
	account := newCodexModelsAPIKeyTestAccount("https://models.example/v1")
	first, err := s.FetchOpenAIModelsList(context.Background(), account)
	require.NoError(t, err)
	expireCodexModelsManifestCache(s, 2*time.Minute)
	_, err = s.FetchOpenAIModelsList(context.Background(), account)
	require.NoError(t, err)
	require.Eventually(t, func() bool {
		s.openAIModelsCache.mu.Lock()
		defer s.openAIModelsCache.mu.Unlock()
		for _, entry := range s.openAIModelsCache.entries {
			return entry.expiresAt.After(time.Now())
		}
		return false
	}, 2*time.Second, time.Millisecond)
	again, err := s.FetchOpenAIModelsList(context.Background(), account)
	require.NoError(t, err)
	require.Equal(t, first.ETag, again.ETag)
	require.Equal(t, string(first.Body), string(again.Body))
	require.EqualValues(t, 2, calls.Load())
}

func TestProjectAccountModelsPassthroughIgnoresStaleMappings(t *testing.T) {
	account := newCodexModelsAPIKeyTestAccount("https://models.example/v1")
	account.Extra = map[string]any{"openai_passthrough": true}
	account.Credentials["model_mapping"] = map[string]any{"obsolete": "missing"}
	body := []byte(`{"object":"list","data":[{"id":"live-model"}]}`)
	projected, err := projectAccountModelsBody(body, account, nil, false)
	require.NoError(t, err)
	require.JSONEq(t, string(body), string(projected))
}

func TestFetchOpenAIModelsListEmptyAndMalformedResponses(t *testing.T) {
	for _, body := range []string{`{"data":[]}`, `{"data":null}`, `{}`, `{"data":{}}`, `{"data":[{}]}`, `{"data":[null]}`} {
		t.Run(body, func(t *testing.T) {
			s := newCodexModelsAPIKeyTestService(&codexModelsHTTPUpstreamStub{do: func(_ *http.Request, _ string, _ int64, _ int) (*http.Response, error) {
				return ordinaryModelsUpstreamResponse(body), nil
			}})
			response, err := s.FetchOpenAIModelsList(context.Background(), newCodexModelsAPIKeyTestAccount("https://models.example/v1"))
			if body != `{"data":[]}` {
				require.Error(t, err)
				require.Equal(t, http.StatusBadGateway, infraerrors.Code(err))
				return
			}
			require.NoError(t, err)
			var result struct {
				Data []json.RawMessage `json:"data"`
			}
			require.NoError(t, json.Unmarshal(response.Body, &result))
			require.NotNil(t, result.Data)
			require.Empty(t, result.Data)
		})
	}
}

func TestPinnedOpenAIModelsListMixedAccountsShareColdCacheAcrossGroups(t *testing.T) {
	_, oauthCalls := newCodexModelsOAuthCacheServer(t, `{"models":[{"slug":"shared-model"},{"slug":"oauth-special"}]}`)
	var apiCalls atomic.Int32
	s := newCodexModelsAPIKeyTestService(&codexModelsHTTPUpstreamStub{do: func(_ *http.Request, _ string, _ int64, _ int) (*http.Response, error) {
		apiCalls.Add(1)
		return ordinaryModelsUpstreamResponse(`{"data":[{"id":"shared-model","owned_by":"api-provider"},{"id":"api-special"}]}`), nil
	}})
	apiAccount := newCodexModelsAPIKeyTestAccount("https://models.example/v1")
	oauthAccount := newCodexModelsTestAccount()
	for _, account := range []*Account{apiAccount, oauthAccount} {
		account.Status, account.Schedulable = StatusActive, true
	}
	accounts := []Account{*apiAccount, *oauthAccount}
	s.accountRepo = splitCodexModelsAccountRepo{all: map[int64][]Account{10: accounts, 11: accounts}}
	groups := []*Group{
		{ID: 10, Platform: PlatformOpenAI, CodexModelsManifestConfig: GroupCodexModelsManifestConfig{Enabled: true, AccountIDs: []int64{2, 1}},
			ModelAllowlist: GroupModelAllowlist{Enabled: true, Models: []string{"oauth-special", "shared-model"}}},
		{ID: 11, Platform: PlatformOpenAI, CodexModelsManifestConfig: GroupCodexModelsManifestConfig{Enabled: true, AccountIDs: []int64{2, 1}}},
	}
	type result struct {
		response *OpenAIModelsResponse
		account  *Account
		err      error
	}
	results := make([]result, len(groups))
	var wait sync.WaitGroup
	for i, group := range groups {
		wait.Add(1)
		go func() {
			defer wait.Done()
			results[i].response, results[i].account, results[i].err = s.FetchPinnedOpenAIModelsList(context.Background(), group, 3, "")
		}()
	}
	wait.Wait()
	for i, result := range results {
		require.NoError(t, result.err)
		require.EqualValues(t, 2, result.account.ID)
		var catalog struct {
			Data []struct {
				ID    string `json:"id"`
				Owner string `json:"owned_by"`
			} `json:"data"`
		}
		require.NoError(t, json.Unmarshal(result.response.Body, &catalog))
		ids := make([]string, 0, len(catalog.Data))
		for _, model := range catalog.Data {
			ids = append(ids, model.ID)
			if model.ID == "shared-model" {
				require.Equal(t, "api-provider", model.Owner)
			}
		}
		if i == 0 {
			require.Equal(t, []string{"oauth-special", "shared-model"}, ids)
		} else {
			require.Equal(t, []string{"shared-model", "api-special", "oauth-special"}, ids)
		}
	}
	require.EqualValues(t, 1, apiCalls.Load())
	require.EqualValues(t, 1, oauthCalls.Load())
}

func TestFetchOpenAIModelsListResolvesShadowOAuthCredentials(t *testing.T) {
	_, calls := newCodexModelsOAuthCacheServer(t, `{"models":[{"slug":"parent-model"}]}`)
	parent := newCodexModelsTestAccount()
	shadow := &Account{ID: 9, Platform: PlatformOpenAI, Type: AccountTypeOAuth, ParentAccountID: &parent.ID}
	s := &OpenAIGatewayService{accountRepo: newStubCredRepo(parent)}
	response, err := s.FetchOpenAIModelsList(context.Background(), shadow)
	require.NoError(t, err)
	require.Contains(t, string(response.Body), `"id":"parent-model"`)
	require.EqualValues(t, 1, calls.Load())
}

func TestProjectAccountModelsCannotExposeCodexMediaThroughAlias(t *testing.T) {
	account := newCodexModelsAPIKeyTestAccount("https://models.example/v1")
	account.Credentials["model_mapping"] = map[string]any{"image-alias": "gpt-image-1", "auto-alias": "codex-auto-fast"}
	body := []byte(`{"models":[{"slug":"gpt-image-1"},{"slug":"codex-auto-fast"}]}`)
	projected, err := projectAccountModelsBody(body, account, &Group{}, true)
	require.NoError(t, err)
	require.JSONEq(t, `{"models":[]}`, string(projected))
}

func TestFetchOpenAIModelsListRejectsUnexpectedCold304(t *testing.T) {
	s := newCodexModelsAPIKeyTestService(&codexModelsHTTPUpstreamStub{do: func(_ *http.Request, _ string, _ int64, _ int) (*http.Response, error) {
		return &http.Response{StatusCode: http.StatusNotModified, Header: make(http.Header), Body: http.NoBody}, nil
	}})
	response, err := s.FetchOpenAIModelsList(context.Background(), newCodexModelsAPIKeyTestAccount("https://models.example/v1"))
	require.Error(t, err)
	require.Nil(t, response)
	require.Equal(t, http.StatusBadGateway, infraerrors.Code(err))
}

func TestOpenAIModelsCacheSeparatesRepresentationsForIdenticalRequests(t *testing.T) {
	s := &OpenAIGatewayService{}
	request := openAIModelsRequest{url: "https://models.example/v1/models", accountID: 7}
	var calls atomic.Int32
	fetch := func(body string) func(context.Context, string) (*OpenAIModelsResponse, error) {
		return func(context.Context, string) (*OpenAIModelsResponse, error) {
			calls.Add(1)
			return &OpenAIModelsResponse{Body: []byte(body)}, nil
		}
	}
	manifestBody := `{"models":[{"slug":"shared"}]}`
	listBody := `{"object":"list","data":[{"id":"shared"}]}`
	_, err := s.fetchCachedOpenAIModels(context.Background(), request, fetch(manifestBody), "")
	require.NoError(t, err)
	request.standardModelsList = true
	list, err := s.fetchCachedOpenAIModels(context.Background(), request, fetch(listBody), "")
	require.NoError(t, err)
	require.JSONEq(t, listBody, string(list.Body))
	request.standardModelsList = false
	manifest, err := s.fetchCachedOpenAIModels(context.Background(), request, fetch(manifestBody), "")
	require.NoError(t, err)
	require.JSONEq(t, manifestBody, string(manifest.Body))
	require.EqualValues(t, 2, calls.Load())
}