opencode-cursor-agent/internal/handlers/anthropic_handler.go

package handlers

import (
	"cursor-api-proxy/internal/agent"
	"cursor-api-proxy/internal/anthropic"
	"cursor-api-proxy/internal/config"
	"cursor-api-proxy/internal/httputil"
	"cursor-api-proxy/internal/logger"
	"cursor-api-proxy/internal/models"
	"cursor-api-proxy/internal/openai"
	"cursor-api-proxy/internal/parser"
	"cursor-api-proxy/internal/pool"
	"cursor-api-proxy/internal/sanitize"
	"cursor-api-proxy/internal/winlimit"
	"cursor-api-proxy/internal/workspace"
	"encoding/json"
	"fmt"
	"net/http"
	"time"

	"github.com/google/uuid"
)

func HandleAnthropicMessages(w http.ResponseWriter, r *http.Request, cfg config.BridgeConfig, lastModelRef *string, rawBody, method, pathname, remoteAddress string) {
	var req anthropic.MessagesRequest
	if err := json.Unmarshal([]byte(rawBody), &req); err != nil {
		httputil.WriteJSON(w, 400, map[string]interface{}{
			"error": map[string]string{"type": "invalid_request_error", "message": "invalid JSON body"},
		}, nil)
		return
	}

	requested := openai.NormalizeModelID(req.Model)
	model := ResolveModel(requested, lastModelRef, cfg)

	// Parse system from raw body to handle both string and array
	var rawMap map[string]interface{}
	_ = json.Unmarshal([]byte(rawBody), &rawMap)

	cleanSystem := sanitize.SanitizeSystem(req.System)

	// SanitizeMessages expects []interface{}
	rawMessages := make([]interface{}, len(req.Messages))
	for i, m := range req.Messages {
		rawMessages[i] = map[string]interface{}{"role": m.Role, "content": m.Content}
	}
	cleanRawMessages := sanitize.SanitizeMessages(rawMessages)

	var cleanMessages []anthropic.MessageParam
	for _, raw := range cleanRawMessages {
		if m, ok := raw.(map[string]interface{}); ok {
			role, _ := m["role"].(string)
			cleanMessages = append(cleanMessages, anthropic.MessageParam{Role: role, Content: m["content"]})
		}
	}

	toolsText := openai.ToolsToSystemText(req.Tools, nil)
	var systemWithTools interface{}
	if toolsText != "" {
		sysStr := ""
		switch v := cleanSystem.(type) {
		case string:
			sysStr = v
		}
		if sysStr != "" {
			systemWithTools = sysStr + "\n\n" + toolsText
		} else {
			systemWithTools = toolsText
		}
	} else {
		systemWithTools = cleanSystem
	}

	prompt := anthropic.BuildPromptFromAnthropicMessages(cleanMessages, systemWithTools)

	if req.MaxTokens == 0 {
		httputil.WriteJSON(w, 400, map[string]interface{}{
			"error": map[string]string{"type": "invalid_request_error", "message": "max_tokens is required"},
		}, nil)
		return
	}

	cursorModel := models.ResolveToCursorModel(model)
	if cursorModel == "" {
		cursorModel = model
	}

	var trafficMsgs []logger.TrafficMessage
	if s := systemToString(cleanSystem); s != "" {
		trafficMsgs = append(trafficMsgs, logger.TrafficMessage{Role: "system", Content: s})
	}
	for _, m := range cleanMessages {
		text := contentToString(m.Content)
		if text != "" {
			trafficMsgs = append(trafficMsgs, logger.TrafficMessage{Role: m.Role, Content: text})
		}
	}
	logger.LogTrafficRequest(cfg.Verbose, model, trafficMsgs, req.Stream)

	headerWs := r.Header.Get("x-cursor-workspace")
	ws := workspace.ResolveWorkspace(cfg, headerWs)

	fixedArgs := agent.BuildAgentFixedArgs(cfg, ws.WorkspaceDir, cursorModel, req.Stream)
	fit := winlimit.FitPromptToWinCmdline(cfg.AgentBin, fixedArgs, prompt, cfg.WinCmdlineMax, ws.WorkspaceDir)

	if !fit.OK {
		httputil.WriteJSON(w, 500, map[string]interface{}{
			"error": map[string]string{"type": "api_error", "message": fit.Error},
		}, nil)
		return
	}
	if fit.Truncated {
		fmt.Printf("[%s] Windows: prompt truncated (%d -> %d chars).\n",
			time.Now().UTC().Format(time.RFC3339), fit.OriginalLength, fit.FinalPromptLength)
	}

	cmdArgs := fit.Args
	msgID := "msg_" + uuid.New().String()

	var truncatedHeaders map[string]string
	if fit.Truncated {
		truncatedHeaders = map[string]string{"X-Cursor-Proxy-Prompt-Truncated": "true"}
	}

	if req.Stream {
		httputil.WriteSSEHeaders(w, truncatedHeaders)
		flusher, _ := w.(http.Flusher)

		writeEvent := func(evt interface{}) {
			data, _ := json.Marshal(evt)
			fmt.Fprintf(w, "data: %s\n\n", data)
			if flusher != nil {
				flusher.Flush()
			}
		}

		writeEvent(map[string]interface{}{
			"type": "message_start",
			"message": map[string]interface{}{
				"id":      msgID,
				"type":    "message",
				"role":    "assistant",
				"model":   model,
				"content": []interface{}{},
			},
		})
		writeEvent(map[string]interface{}{
			"type":          "content_block_start",
			"index":         0,
			"content_block": map[string]string{"type": "text", "text": ""},
		})

		var accumulated string
		parseLine := parser.CreateStreamParser(
			func(text string) {
				accumulated += text
				writeEvent(map[string]interface{}{
					"type":  "content_block_delta",
					"index": 0,
					"delta": map[string]string{"type": "text_delta", "text": text},
				})
			},
			func() {
				logger.LogTrafficResponse(cfg.Verbose, model, accumulated, true)
				writeEvent(map[string]interface{}{"type": "content_block_stop", "index": 0})
				writeEvent(map[string]interface{}{
					"type":  "message_delta",
					"delta": map[string]interface{}{"stop_reason": "end_turn", "stop_sequence": nil},
					"usage": map[string]int{"output_tokens": 0},
				})
				writeEvent(map[string]interface{}{"type": "message_stop"})
			},
		)

		configDir := pool.GetNextAccountConfigDir()
		logger.LogAccountAssigned(configDir)
		pool.ReportRequestStart(configDir)
		streamStart := time.Now().UnixMilli()

		ctx := r.Context()
		result, err := agent.RunAgentStreamWithContext(cfg, ws.WorkspaceDir, cmdArgs, parseLine, ws.TempDir, configDir, ctx)

		latencyMs := time.Now().UnixMilli() - streamStart
		pool.ReportRequestEnd(configDir)

		if err == nil && isRateLimited(result.Stderr) {
			pool.ReportRateLimit(configDir, 60000)
		}
		if err != nil || result.Code != 0 {
			pool.ReportRequestError(configDir, latencyMs)
			if err != nil {
				logger.LogAgentError(cfg.SessionsLogPath, method, pathname, remoteAddress, -1, err.Error())
			} else {
				logger.LogAgentError(cfg.SessionsLogPath, method, pathname, remoteAddress, result.Code, result.Stderr)
			}
		} else {
			pool.ReportRequestSuccess(configDir, latencyMs)
		}
		logger.LogAccountStats(cfg.Verbose, pool.GetAccountStats())
		return
	}

	configDir := pool.GetNextAccountConfigDir()
	logger.LogAccountAssigned(configDir)
	pool.ReportRequestStart(configDir)
	syncStart := time.Now().UnixMilli()

	out, err := agent.RunAgentSync(cfg, ws.WorkspaceDir, cmdArgs, ws.TempDir, configDir, r.Context())
	syncLatency := time.Now().UnixMilli() - syncStart
	pool.ReportRequestEnd(configDir)

	if err != nil {
		pool.ReportRequestError(configDir, syncLatency)
		logger.LogAccountStats(cfg.Verbose, pool.GetAccountStats())
		httputil.WriteJSON(w, 500, map[string]interface{}{
			"error": map[string]string{"type": "api_error", "message": err.Error()},
		}, nil)
		return
	}

	if isRateLimited(out.Stderr) {
		pool.ReportRateLimit(configDir, 60000)
	}

	if out.Code != 0 {
		pool.ReportRequestError(configDir, syncLatency)
		logger.LogAccountStats(cfg.Verbose, pool.GetAccountStats())
		errMsg := logger.LogAgentError(cfg.SessionsLogPath, method, pathname, remoteAddress, out.Code, out.Stderr)
		httputil.WriteJSON(w, 500, map[string]interface{}{
			"error": map[string]string{"type": "api_error", "message": errMsg},
		}, nil)
		return
	}

	pool.ReportRequestSuccess(configDir, syncLatency)
	content := trimSpace(out.Stdout)
	logger.LogTrafficResponse(cfg.Verbose, model, content, false)
	logger.LogAccountStats(cfg.Verbose, pool.GetAccountStats())

	httputil.WriteJSON(w, 200, map[string]interface{}{
		"id":         msgID,
		"type":       "message",
		"role":       "assistant",
		"content":    []map[string]string{{"type": "text", "text": content}},
		"model":      model,
		"stop_reason": "end_turn",
		"usage":      map[string]int{"input_tokens": 0, "output_tokens": 0},
	}, truncatedHeaders)
}

func systemToString(system interface{}) string {
	switch v := system.(type) {
	case string:
		return v
	case []interface{}:
		result := ""
		for _, p := range v {
			if m, ok := p.(map[string]interface{}); ok && m["type"] == "text" {
				if t, ok := m["text"].(string); ok {
					result += t
				}
			}
		}
		return result
	}
	return ""
}

func contentToString(content interface{}) string {
	switch v := content.(type) {
	case string:
		return v
	case []interface{}:
		result := ""
		for _, p := range v {
			if m, ok := p.(map[string]interface{}); ok && m["type"] == "text" {
				if t, ok := m["text"].(string); ok {
					result += t
				}
			}
		}
		return result
	}
	return ""
}