package server

import (
	"context"
	"encoding/json"
	"fmt"
	"os"
	"path"
	"time"

	"codelab/ai-agent/internal/agent"
	"codelab/ai-agent/internal/log"

	"github.com/gin-gonic/gin"
	"github.com/google/generative-ai-go/genai"
	"google.golang.org/api/iterator"
	"google.golang.org/api/option"
)

var (
	GoogleAIKey    string
	GoogleAIModel  string
	CandidateCount = int32(1)
	Temperature    = float32(0.8)
)

type OpenAIMessage struct {
	Role string `json:"role"`
	Msg  string `json:"content"`
}

type ChatRequest struct {
	OpenAIMessages  []*OpenAIMessage
	Agent           *agent.Agent
	ClientIP        string
	ClientUserAgent string
	ResWriter       gin.ResponseWriter
	LogPath         string
}

type MessageLogEntry struct {
	Timestamp       time.Time            `json:"timestamp"`
	UserMsg         string               `json:"userMsg"`
	ModelMsg        string               `json:"modelMsg"`
	Feedback        genai.PromptFeedback `json:"feedback"`
	Usage           genai.UsageMetadata  `json:"usage"`
	ClientIP        string               `json:"clientIP"`
	ClientUserAgent string               `json:"clientUserAgent"`
}

func openaiToGoogle(msgs []*OpenAIMessage) []*genai.Content {
	g := []*genai.Content{}
	for _, msg := range msgs {
		if msg.Role == "system" {
			continue
		}
		g = append(g, &genai.Content{
			Role: msg.Role,
			Parts: []genai.Part{
				genai.Text(msg.Msg),
			},
		})
	}
	return g
}

func (r *ChatRequest) Chat() error {
	ctx := context.Background()
	client, err := genai.NewClient(ctx, option.WithAPIKey(GoogleAIKey))
	if err != nil {
		return err
	}

	defer client.Close()
	model := client.GenerativeModel(GoogleAIModel)
	model.SafetySettings = []*genai.SafetySetting{
		{
			Category:  genai.HarmCategoryDangerousContent,
			Threshold: genai.HarmBlockOnlyHigh,
		},
		{
			Category:  genai.HarmCategoryHateSpeech,
			Threshold: genai.HarmBlockOnlyHigh,
		},
		{
			Category:  genai.HarmCategorySexuallyExplicit,
			Threshold: genai.HarmBlockOnlyHigh,
		},
		{
			Category:  genai.HarmCategoryHarassment,
			Threshold: genai.HarmBlockNone,
		},
	}
	model.GenerationConfig = genai.GenerationConfig{
		CandidateCount: &CandidateCount,
		Temperature:    &Temperature,
	}
	model.SystemInstruction = genai.NewUserContent(genai.Text(r.Agent.SystemPrompt))
	model.GenerateContentStream(ctx)

	chat := model.StartChat()
	msgs := append([]*genai.Content{
		{
			Role: "user",
			Parts: []genai.Part{
				genai.Text(r.Agent.InitialPrompt),
			},
		},
	}, openaiToGoogle(r.OpenAIMessages)...)
	chat.History = msgs[:len(msgs)-1]

	iter := chat.SendMessageStream(ctx, msgs[len(msgs)-1].Parts...)
	iterConut := 0
	for {
		iterConut++
		log.T("server/ai").Dbgf("AI response #%d", iterConut)
		res, err := iter.Next()
		if err == iterator.Done {
			break
		}
		if err != nil {
			log.T("server/ai").Errf("Failed to get response: %v", err)
		}
		r.writeResp(res)
	}
	log.T("server/ai").Dbgf("AI Response took %d iterations", iterConut)

	res := iter.MergedResponse()
	answer := ""
	if len(res.Candidates) > 0 {
		for _, part := range res.Candidates[0].Content.Parts {
			answer += fmt.Sprint(part)
		}
	} else {
		answer = "<no response>"
	}

	feedback := res.PromptFeedback
	if feedback == nil {
		log.T("server/ai").Errf("Server response feedback is nil")
		feedback = &genai.PromptFeedback{}
	}

	usage := res.UsageMetadata
	if usage == nil {
		log.T("server/ai").Errf("Server response usage is nil")
		usage = &genai.UsageMetadata{}
	}

	log.T("server/ai").Dbgf("usage: %+v", usage)
	usageJSON, err := json.Marshal(usage)
	if err != nil {
		log.T("server/ai").Errf("Failed to marshal usage data: %v", err)
	} else {
		_, err = r.ResWriter.Write([]byte(fmt.Sprintf("data: %s\n\n", usageJSON)))
		r.ResWriter.Flush()
		if err != nil {
			log.T("server/ai").Errf("Failed to write usage data: %v", err)
		}
	}
	_, err = r.ResWriter.Write([]byte("data: [DONE]"))
	r.ResWriter.Flush()
	if err != nil {
		log.T("server/ai").Errf("Failed to write done message: %v", err)
	}

	ok := r.EnsureLogPath()
	if !ok {
		log.T("server/ai").Errf("Failed to ensure log path exists")
		return nil
	}

	msgLogEntry := MessageLogEntry{
		Timestamp:       time.Now(),
		UserMsg:         r.OpenAIMessages[len(r.OpenAIMessages)-1].Msg,
		ModelMsg:        answer,
		Feedback:        *feedback,
		Usage:           *usage,
		ClientIP:        r.ClientIP,
		ClientUserAgent: r.ClientUserAgent,
	}
	logEntryJSON, err := json.Marshal(msgLogEntry)
	if err != nil {
		log.T("server/ai").Errf("Failed to marshal log entry: %v", err)
		return nil
	}
	msgLogPath := path.Join(r.LogPath, fmt.Sprintf("%s.ndjson", r.Agent.AgentID))
	msgLogFile, err := os.OpenFile(msgLogPath, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
	if err != nil {
		log.T("server/ai").Errf("Failed to open log file: %v", err)
		return nil
	}
	defer msgLogFile.Close()
	_, err = msgLogFile.Write([]byte(fmt.Sprintf("%s\n", logEntryJSON)))
	if err != nil {
		log.T("server/ai").Errf("Failed to write log entry: %v", err)
	}

	return nil
}

func (req *ChatRequest) writeResp(res *genai.GenerateContentResponse) {
	fullAnswerContent := ""
	answer := res.Candidates[0]
	if answer == nil {
		return
	}
	for i, part := range answer.Content.Parts {
		log.T("server/ai").Dbgf("  - AI response part #%d: %s", i+1, part)
		content := fmt.Sprint(part)
		fullAnswerContent += content
		contentJSON, err := json.Marshal(gin.H{"content": content})
		if err != nil {
			log.T("server/ai").Errf("Failed to marshal response: %v", err)
			continue
		}
		_, err = req.ResWriter.Write([]byte(fmt.Sprintf("data: %s\n\n", contentJSON)))
		req.ResWriter.Flush()
		if err != nil {
			log.T("server/ai").Errf("Failed to write response: %v", err)
		}
	}
}

func (r *ChatRequest) EnsureLogPath() bool {
	if r.LogPath == "" {
		return false
	}
	stat, err := os.Stat(r.LogPath)
	if err != nil && os.IsNotExist(err) {
		err = os.MkdirAll(r.LogPath, 0755)
		if err != nil {
			log.T("server/ai").Errf("Failed to create log path: %v", err)
			return false
		}
	} else if err != nil {
		log.T("server/ai").Errf("Failed to stat log path: %v", err)
		return false
	} else {
		if !stat.IsDir() {
			log.T("server/ai").Errf("Log path is not a directory: %s", r.LogPath)
			return false
		}
	}

	return true
}