package webui

import (
	"context"
	"fmt"
	"time"

	"encoding/json"
	agentIO "gitcode.com/JianFeeeee/HomeAgent/internal/agent/io"
	"net/http"
)

// OpenAI 兼容面：/v1/chat/completions（含流式）。

func (h *Handler) handleOpenAICompletions(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
		return
	}

	if h.sdk == nil {
		writeJSON(w, http.StatusServiceUnavailable, map[string]string{"error": "IO manager not available"})
		return
	}

	var req struct {
		Model       string          `json:"model"`
		Messages    []openAIMessage `json:"messages"`
		Stream      bool            `json:"stream"`
		Temperature float64         `json:"temperature"`
		MaxTokens   int             `json:"max_tokens"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid request: " + err.Error()})
		return
	}
	if len(req.Messages) == 0 {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "messages is required"})
		return
	}

	lastMsg := req.Messages[len(req.Messages)-1]
	if lastMsg.Role != "user" {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "last message must be from user"})
		return
	}

	// 带超时的上下文（同 handleChat：客户端断开立即取消；300s 约束长生成）
	ctx, cancel := context.WithTimeout(r.Context(), 300*time.Second)
	defer cancel()

	respCh := make(chan *agentIO.OutputEvent, 1)
	go func() {
		// NoMemory：本端点（OpenAI 兼容 /v1/chat/completions）的调用方是
		// IDE、工具与脚本，送来的是**固定的提示词模板**（"请分析这段代码"之类），
		// 不是人类在对话。记进记忆会把真实对话挤掉，而且同一模板会反复刷屏。
		// 原文仍进上下文，模型照旧看得到；只是不参与向量化/关键词提取/蒸馏。
		respCh <- h.sdk.InjectTextSyncNoMemory("http", "http", lastMsg.Content)
	}()

	var response *agentIO.OutputEvent
	select {
	case response = <-respCh:
	case <-ctx.Done():
		writeJSON(w, http.StatusGatewayTimeout, map[string]string{"error": "agent timeout (300s)"})
		return
	}

	if response == nil {
		writeJSON(w, http.StatusServiceUnavailable, map[string]string{"error": "no response from agent"})
		return
	}

	content, _ := response.Payload["content"].(string)
	reasoningContent, _ := response.Payload["reasoning_content"].(string)
	usage, _ := response.Payload["usage"].(map[string]interface{})

	if req.Stream {
		h.writeOpenAIStream(w, req.Model, content, reasoningContent, usage)
		return
	}

	resp := map[string]interface{}{
		"id":      fmt.Sprintf("chatcmpl-%d", time.Now().UnixNano()),
		"object":  "chat.completion",
		"created": time.Now().Unix(),
		"model":   req.Model,
		"choices": []map[string]interface{}{
			{
				"index": 0,
				"message": map[string]interface{}{
					"role":    "assistant",
					"content": content,
				},
				"finish_reason": "stop",
			},
		},
	}
	if reasoningContent != "" {
		resp["choices"].([]map[string]interface{})[0]["message"].(map[string]interface{})["reasoning_content"] = reasoningContent
	}
	if usage != nil {
		resp["usage"] = usage
	}

	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	json.NewEncoder(w).Encode(resp)
}

func (h *Handler) writeOpenAIStream(w http.ResponseWriter, model, content, reasoningContent string, usage map[string]interface{}) {
	flusher, ok := w.(http.Flusher)
	if !ok {
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": "streaming not supported"})
		return
	}

	w.Header().Set("Content-Type", "text/event-stream")
	w.Header().Set("Cache-Control", "no-cache")
	w.Header().Set("Connection", "keep-alive")
	w.WriteHeader(http.StatusOK)
	flusher.Flush()

	// 如果有 reasoning_content，先发送一个 reasoning chunk
	if reasoningContent != "" {
		reasoningChunk := map[string]interface{}{
			"id":      fmt.Sprintf("chatcmpl-%d", time.Now().UnixNano()),
			"object":  "chat.completion.chunk",
			"created": time.Now().Unix(),
			"model":   model,
			"choices": []map[string]interface{}{
				{
					"index": 0,
					"delta": map[string]interface{}{
						"content":           "",
						"reasoning_content": reasoningContent,
					},
					"finish_reason": nil,
				},
			},
		}
		data, _ := json.Marshal(reasoningChunk)
		fmt.Fprintf(w, "data: %s\n\n", data)
		flusher.Flush()
	}

	// content chunk
	contentChunk := map[string]interface{}{
		"id":      fmt.Sprintf("chatcmpl-%d", time.Now().UnixNano()),
		"object":  "chat.completion.chunk",
		"created": time.Now().Unix(),
		"model":   model,
		"choices": []map[string]interface{}{
			{
				"index": 0,
				"delta": map[string]interface{}{
					"content": content,
				},
				"finish_reason": nil,
			},
		},
	}
	data, _ := json.Marshal(contentChunk)
	fmt.Fprintf(w, "data: %s\n\n", data)
	flusher.Flush()

	// finish chunk
	finishChunk := map[string]interface{}{
		"id":      fmt.Sprintf("chatcmpl-%d", time.Now().UnixNano()),
		"object":  "chat.completion.chunk",
		"created": time.Now().Unix(),
		"model":   model,
		"choices": []map[string]interface{}{
			{
				"index":         0,
				"delta":         map[string]interface{}{},
				"finish_reason": "stop",
			},
		},
	}
	if usage != nil {
		finishChunk["usage"] = usage
	}
	data, _ = json.Marshal(finishChunk)
	fmt.Fprintf(w, "data: %s\n\n", data)
	flusher.Flush()

	fmt.Fprintf(w, "data: [DONE]\n\n")
	flusher.Flush()
}

type openAIMessage struct {
	Role    string `json:"role"`
	Content string `json:"content"`
}