package proxy

import (
	"encoding/json"

	"openteam/server/internal/proxy/claude"
	"openteam/server/internal/proxy/openai"
	"openteam/server/internal/proxy/responses"
)

// parseUsageForProtocol extracts token usage from a non-stream response body.
func parseUsageForProtocol(proto Protocol, body []byte) *tokenUsage {
	switch proto {
	case ProtocolAnthropic:
		var mr claude.MessageResponse
		if err := json.Unmarshal(body, &mr); err != nil || mr.Usage == nil {
			return nil
		}
		return &tokenUsage{
			input:         mr.Usage.InputTokens,
			output:        mr.Usage.OutputTokens,
			cacheRead:     mr.Usage.CacheReadInputTokens,
			cacheCreation: mr.Usage.CacheCreationInputTokens,
		}
	case ProtocolOpenAIResponses:
		var r responses.Response
		if err := json.Unmarshal(body, &r); err != nil || r.Usage == nil {
			return nil
		}
		return &tokenUsage{
			input:     r.Usage.InputTokens,
			output:    r.Usage.OutputTokens,
			cacheRead: r.Usage.InputTokensDetails.CachedTokens,
		}
	default:
		var cc openai.ChatCompletion
		if err := json.Unmarshal(body, &cc); err != nil || cc.Usage == nil {
			return nil
		}
		return &tokenUsage{input: cc.Usage.PromptTokens, output: cc.Usage.CompletionTokens}
	}
}

// estimateTokensFromText is a coarse fallback used when the upstream omits usage.
func estimateTokensFromText(s string) int64 {
	// ~4 chars per token, per OpenAI's common heuristic.
	return int64(len(s)/4 + 1)
}