package clients

import (
	"bytes"
	"context"
	"encoding/json"
	"net/http"
	"strings"
	"time"

	"github.com/easyai/easyai-ai-gateway/apps/api/internal/store"
)

type OpenAIClient struct {
	HTTPClient *http.Client
}

func (c OpenAIClient) Run(ctx context.Context, request Request) (Response, error) {
	apiKey := credential(request.Candidate.Credentials, "apiKey", "api_key", "key", "token")
	if apiKey == "" {
		return Response{}, &ClientError{Code: "missing_credentials", Message: "openai api key is required", Retryable: false}
	}
	protocol := request.UpstreamProtocol
	if protocol == "" && request.Kind == "responses" {
		protocol = ProtocolOpenAIResponses
	}
	endpointKind := request.Kind
	if request.Kind == "responses" && protocol == ProtocolOpenAIChatCompletions {
		endpointKind = "chat.completions"
	}
	endpoint := openAIEndpoint(endpointKind)
	if endpoint == "" {
		return Response{}, &ClientError{Code: "unsupported_kind", Message: "unsupported openai request kind", Retryable: false}
	}
	body := cloneBody(request.Body)
	if request.Kind == "responses" && protocol == ProtocolOpenAIChatCompletions {
		var convertErr error
		body, convertErr = ResponsesRequestToChat(request.Body, request.PreviousResponseTurns)
		if convertErr != nil {
			return Response{}, convertErr
		}
	}
	if endpointKind == "chat.completions" {
		body = NormalizeChatCompletionRequestBody(body)
		applyOpenAIChatReasoningParams(body, request.Candidate)
	} else if request.Kind == "responses" {
		delete(body, "messages")
		if request.UpstreamPreviousResponseID != "" {
			body["previous_response_id"] = request.UpstreamPreviousResponseID
		} else {
			delete(body, "previous_response_id")
		}
	}
	body["model"] = upstreamModelName(request.Candidate)
	stream := openAIEndpointSupportsStream(endpointKind) && (request.Stream || boolValue(body, "stream"))
	ensureOpenAIStreamUsage(body, endpointKind, stream)
	raw, _ := json.Marshal(body)
	upstreamEndpoint := joinURL(openAIBaseURL(endpointKind, request.Candidate), endpoint)
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, upstreamEndpoint, bytes.NewReader(raw))
	if err != nil {
		return Response{}, err
	}
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Authorization", "Bearer "+apiKey)
	responseStartedAt := time.Now()
	resp, err := httpClient(request.HTTPClient, c.HTTPClient).Do(req)
	if err != nil {
		return Response{}, &ClientError{Code: "network", Message: err.Error(), Retryable: true}
	}
	requestID := requestIDFromHTTPResponse(resp)
	var result map[string]any
	upstreamResponseID := ""
	if request.Kind == "responses" && protocol == ProtocolOpenAIResponses && stream {
		result, upstreamResponseID, err = decodeNativeResponsesStream(resp, request.StreamDelta)
	} else {
		var streamDelta StreamDelta = request.StreamDelta
		var adapter *chatResponsesStreamAdapter
		if request.Kind == "responses" && protocol == ProtocolOpenAIChatCompletions && stream {
			adapter = newChatResponsesStreamAdapter(request.PublicResponseID, request.Model)
			streamDelta = func(event StreamDeltaEvent) error { return adapter.delta(event, request.StreamDelta) }
		}
		result, err = decodeOpenAIResponse(resp, stream, streamDelta)
		if err == nil && endpointKind == "chat.completions" {
			result = NormalizeChatCompletionResult(result)
		}
		if err == nil && request.Kind == "responses" && protocol == ProtocolOpenAIChatCompletions {
			chatResult := result
			upstreamResponseID = requestIDFromResult(chatResult)
			result = ChatResultToResponse(chatResult, request.PublicResponseID, request.Model, request.Body)
			if adapter != nil {
				err = adapter.done(result, request.StreamDelta)
			}
			if err == nil {
				return Response{
					Result: result, InternalResult: chatResult, RequestID: firstNonEmptyString(requestID, upstreamResponseID), Usage: usageFromOpenAI(chatResult),
					Progress: providerProgress(request), ResponseStartedAt: responseStartedAt, ResponseFinishedAt: time.Now(),
					UpstreamProtocol: protocol, UpstreamEndpoint: endpoint, UpstreamResponseID: upstreamResponseID,
					PublicResponseID: request.PublicResponseID, ResponseConverted: true,
				}, nil
			}
		}
	}
	if err == nil && request.Kind == "chat.completions" {
		result = NormalizeChatCompletionResult(result)
	}
	responseFinishedAt := time.Now()
	if err != nil {
		return Response{}, annotateResponseError(err, requestID, responseStartedAt, responseFinishedAt)
	}
	if requestID == "" {
		requestID = requestIDFromResult(result)
	}
	if request.Kind == "responses" && protocol == ProtocolOpenAIResponses {
		if upstreamResponseID == "" {
			upstreamResponseID = requestIDFromResult(result)
		}
	}
	publicResponseID := request.PublicResponseID
	if request.Kind == "responses" && protocol == ProtocolOpenAIResponses {
		publicResponseID = upstreamResponseID
	}
	return Response{
		Result:             result,
		RequestID:          requestID,
		Usage:              usageFromOpenAI(result),
		Progress:           providerProgress(request),
		ResponseStartedAt:  responseStartedAt,
		ResponseFinishedAt: responseFinishedAt,
		ResponseDurationMS: responseDurationMS(responseStartedAt, responseFinishedAt),
		UpstreamProtocol:   protocol,
		UpstreamEndpoint:   endpoint,
		UpstreamResponseID: upstreamResponseID,
		PublicResponseID:   publicResponseID,
	}, nil
}

func decodeOpenAIResponse(resp *http.Response, stream bool, onDelta StreamDelta) (map[string]any, error) {
	if stream {
		result, err := decodeOpenAIStreamResponse(resp, onDelta)
		if err == nil {
			return result, nil
		}
		return nil, err
	}
	return decodeHTTPResponse(resp)
}

func openAIEndpoint(kind string) string {
	switch kind {
	case "chat.completions":
		return "/chat/completions"
	case "responses":
		return "/responses"
	case "embeddings":
		return "/embeddings"
	case "reranks":
		return "/reranks"
	case "images.generations":
		return "/images/generations"
	case "images.edits":
		return "/images/edits"
	default:
		return ""
	}
}

func openAIEndpointSupportsStream(kind string) bool {
	return kind == "chat.completions" || kind == "responses"
}

func openAIBaseURL(kind string, candidate store.RuntimeModelCandidate) string {
	base := strings.TrimSpace(candidate.BaseURL)
	if kind != "reranks" {
		return base
	}
	if strings.Contains(base, "/compatible-mode/") && (strings.EqualFold(candidate.Provider, "aliyun-bailian-openai") || strings.Contains(base, "dashscope")) {
		return strings.Replace(base, "/compatible-mode/", "/compatible-api/", 1)
	}
	if base == "" && strings.EqualFold(candidate.Provider, "aliyun-bailian-openai") {
		return "https://dashscope.aliyuncs.com/compatible-api/v1"
	}
	return base
}

func cloneBody(body map[string]any) map[string]any {
	out := map[string]any{}
	for key, value := range body {
		out[key] = value
	}
	return out
}

func ensureOpenAIStreamUsage(body map[string]any, kind string, stream bool) {
	if !stream || kind != "chat.completions" {
		return
	}
	streamOptions := map[string]any{}
	if existing, ok := body["stream_options"].(map[string]any); ok {
		for key, value := range existing {
			streamOptions[key] = value
		}
	}
	streamOptions["include_usage"] = true
	body["stream_options"] = streamOptions
}

func joinURL(base string, path string) string {
	base = strings.TrimRight(strings.TrimSpace(base), "/")
	if base == "" {
		base = "https://api.openai.com/v1"
	}
	return base + path
}

func httpClient(clients ...*http.Client) *http.Client {
	for _, client := range clients {
		if client != nil {
			return client
		}
	}
	return http.DefaultClient
}

func providerProgress(request Request) []Progress {
	return []Progress{
		{Phase: "submitting", Progress: 0.35, Message: "provider request submitted", Payload: map[string]any{"clientId": request.Candidate.ClientID}},
		{Phase: "fetching_result", Progress: 0.8, Message: "provider response received", Payload: map[string]any{"provider": request.Candidate.Provider}},
	}
}