package httpapi

import "net/http"

func prepareCompatibleStream(w http.ResponseWriter) http.Flusher {
	w.Header().Set("Content-Type", "text/event-stream")
	w.Header().Set("Cache-Control", "no-cache")
	w.Header().Set("Connection", "keep-alive")
	flusher, _ := w.(http.Flusher)
	return flusher
}

func writeCompatibleDelta(w http.ResponseWriter, kind string, model string, content string) {
	if kind == "responses" {
		sendSSE(w, "response.output_text.delta", map[string]any{"type": "response.output_text.delta", "delta": content})
		return
	}
	sendSSE(w, "message", map[string]any{
		"id":      "chatcmpl-stream",
		"object":  "chat.completion.chunk",
		"model":   model,
		"choices": []any{map[string]any{"index": 0, "delta": map[string]any{"content": content}, "finish_reason": nil}},
	})
}

func writeCompatibleDone(w http.ResponseWriter, kind string, model string, output map[string]any) {
	if kind == "responses" {
		sendSSE(w, "response.completed", map[string]any{"type": "response.completed", "response": output})
		return
	}
	sendSSE(w, "message", map[string]any{
		"id":      firstString(output["id"], "chatcmpl-stream"),
		"object":  "chat.completion.chunk",
		"model":   model,
		"choices": []any{map[string]any{"index": 0, "delta": map[string]any{}, "finish_reason": "stop"}},
	})
}

func writeCompatibleStream(w http.ResponseWriter, kind string, model string, output map[string]any) {
	prepareCompatibleStream(w)
	content := extractOutputText(output)
	if content == "" {
		content = "done"
	}
	if kind == "responses" {
		sendSSE(w, "response.output_text.delta", map[string]any{"type": "response.output_text.delta", "delta": content})
		sendSSE(w, "response.completed", map[string]any{"type": "response.completed", "response": output})
		return
	}
	sendSSE(w, "message", map[string]any{
		"id":      output["id"],
		"object":  "chat.completion.chunk",
		"model":   model,
		"choices": []any{map[string]any{"index": 0, "delta": map[string]any{"content": content}, "finish_reason": nil}},
	})
	sendSSE(w, "message", map[string]any{
		"id":      output["id"],
		"object":  "chat.completion.chunk",
		"model":   model,
		"choices": []any{map[string]any{"index": 0, "delta": map[string]any{}, "finish_reason": "stop"}},
	})
}

func firstString(value any, fallback string) string {
	if text, ok := value.(string); ok && text != "" {
		return text
	}
	return fallback
}

func extractOutputText(output map[string]any) string {
	if text, ok := output["output_text"].(string); ok {
		return text
	}
	choices, _ := output["choices"].([]any)
	for _, rawChoice := range choices {
		choice, _ := rawChoice.(map[string]any)
		message, _ := choice["message"].(map[string]any)
		if content, ok := message["content"].(string); ok {
			return content
		}
	}
	return ""
}