package runner

import (
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"strings"
)

func buildCacheAffinityKey(kind string, modelType string, body map[string]any) string {
	if len(body) == 0 {
		return ""
	}
	for _, key := range []string{"cacheAffinityKey", "cache_affinity_key"} {
		if value := strings.TrimSpace(stringFromAny(body[key])); value != "" {
			return "explicit:" + sha256Text(value)
		}
	}
	for _, key := range []string{"sessionId", "session_id", "conversationId", "conversation_id"} {
		if value := strings.TrimSpace(stringFromAny(body[key])); value != "" {
			return key + ":" + sha256Text(value)
		}
	}
	if !cacheAffinityPromptHashSupported(kind, modelType) {
		return ""
	}
	payload := map[string]any{
		"kind":      kind,
		"modelType": modelType,
	}
	if messages, ok := body["messages"]; ok {
		payload["messages"] = messages
	}
	if tools, ok := body["tools"]; ok {
		payload["tools"] = tools
	}
	if instructions, ok := body["instructions"]; ok {
		payload["instructions"] = instructions
	}
	if input, ok := body["input"]; ok {
		payload["input"] = input
	}
	if len(payload) <= 2 {
		return ""
	}
	raw, err := json.Marshal(payload)
	if err != nil || len(raw) == 0 {
		return ""
	}
	return "prompt:" + sha256Text(string(raw))
}

func cacheAffinityPromptHashSupported(kind string, modelType string) bool {
	switch strings.TrimSpace(kind) {
	case "chat.completions", "responses":
		return true
	}
	switch strings.TrimSpace(modelType) {
	case "chat", "text_generate", "responses":
		return true
	default:
		return false
	}
}

func sha256Text(value string) string {
	sum := sha256.Sum256([]byte(value))
	return hex.EncodeToString(sum[:])
}