package main

import (
	"bufio"
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"strings"
	"time"

	"github.com/gofiber/fiber/v2"
	"github.com/gofiber/fiber/v2/middleware/cors"
	"github.com/gofiber/fiber/v2/middleware/logger"
	"github.com/gooseek/backend/pkg/config"
	"github.com/gooseek/backend/pkg/middleware"
)

type ChatRequest struct {
	Message struct {
		MessageID string `json:"messageId"`
		ChatID    string `json:"chatId"`
		Content   string `json:"content"`
	} `json:"message"`
	OptimizationMode   string     `json:"optimizationMode"`
	Sources            []string   `json:"sources"`
	History            [][]string `json:"history"`
	Files              []string   `json:"files"`
	ChatModel          ChatModel  `json:"chatModel"`
	EmbeddingModel     ChatModel  `json:"embeddingModel"`
	SystemInstructions string     `json:"systemInstructions"`
	Locale             string     `json:"locale"`
	AnswerMode         string     `json:"answerMode"`
	ResponsePrefs      *struct {
		Format string `json:"format"`
		Length string `json:"length"`
		Tone   string `json:"tone"`
	} `json:"responsePrefs"`
	LearningMode bool `json:"learningMode"`
}

type ChatModel struct {
	ProviderID string `json:"providerId"`
	Key        string `json:"key"`
}

func main() {
	cfg, err := config.Load()
	if err != nil {
		log.Fatal("Failed to load config:", err)
	}

	app := fiber.New(fiber.Config{
		StreamRequestBody: true,
		BodyLimit:         50 * 1024 * 1024,
		ReadTimeout:       time.Minute,
		WriteTimeout:      5 * time.Minute,
		IdleTimeout:       2 * time.Minute,
	})

	app.Use(logger.New())
	app.Use(cors.New())

	app.Get("/health", func(c *fiber.Ctx) error {
		return c.JSON(fiber.Map{"status": "ok"})
	})

	app.Get("/ready", func(c *fiber.Ctx) error {
		return c.JSON(fiber.Map{"status": "ready"})
	})

	app.Get("/metrics", func(c *fiber.Ctx) error {
		c.Set("Content-Type", "text/plain; charset=utf-8")
		return c.SendString(
			"# HELP gooseek_up Service is up (1) or down (0)\n" +
				"# TYPE gooseek_up gauge\n" +
				"gooseek_up 1\n",
		)
	})

	app.Get("/api/v1/config", func(c *fiber.Ctx) error {
		return c.JSON(fiber.Map{
			"values": fiber.Map{
				"version":       1,
				"setupComplete": true,
				"preferences":   fiber.Map{},
			},
			"fields":         fiber.Map{},
			"modelProviders": []interface{}{},
			"envOnlyMode":    true,
		})
	})

	chat := app.Group("/api/v1/chat", middleware.JWT(middleware.JWTConfig{
		Secret:     cfg.JWTSecret,
		AuthSvcURL: cfg.AuthSvcURL,
		AllowGuest: false,
	}))

	chat.Post("/", func(c *fiber.Ctx) error {
		var req ChatRequest
		if err := c.BodyParser(&req); err != nil {
			return c.Status(400).JSON(fiber.Map{"error": "Invalid request body"})
		}

		if req.Message.Content == "" {
			return c.Status(400).JSON(fiber.Map{"error": "Message content required"})
		}

		isDiscoverSummary := strings.HasPrefix(req.Message.Content, "Summary: ") && len(req.Message.Content) > 9
		var summaryURL string
		if isDiscoverSummary {
			summaryURL = strings.TrimSpace(strings.TrimPrefix(req.Message.Content, "Summary: "))
		}

		agentURL := strings.TrimSuffix(cfg.AgentSvcURL, "/") + "/api/v1/agents/search"

		httpReq, err := http.NewRequest("POST", agentURL, bytes.NewReader(c.Body()))
		if err != nil {
			return c.Status(500).JSON(fiber.Map{"error": err.Error()})
		}

		httpReq.Header.Set("Content-Type", "application/json")
		if auth := c.Get("Authorization"); auth != "" {
			httpReq.Header.Set("Authorization", auth)
		}

		client := &http.Client{Timeout: 5 * time.Minute}
		resp, err := client.Do(httpReq)
		if err != nil {
			log.Printf("Agent service error: %v", err)
			return c.Status(503).JSON(fiber.Map{"error": "Agent service unavailable"})
		}

		if resp.StatusCode != http.StatusOK {
			body, _ := io.ReadAll(resp.Body)
			resp.Body.Close()
			return c.Status(resp.StatusCode).Send(body)
		}

		c.Set("Content-Type", "application/x-ndjson")
		c.Set("Cache-Control", "no-cache")
		c.Set("Connection", "keep-alive")

		if isDiscoverSummary && summaryURL != "" && cfg.DiscoverSvcURL != "" {
			collected := make([]string, 0)
			scanner := bufio.NewScanner(resp.Body)
			scanner.Buffer(make([]byte, 1024*1024), 10*1024*1024)

			var result bytes.Buffer
			for scanner.Scan() {
				line := scanner.Text()
				if strings.TrimSpace(line) != "" {
					collected = append(collected, line)
					result.WriteString(line + "\n")
				}
			}
			resp.Body.Close()

			if len(collected) > 0 {
				go saveArticleSummary(cfg.DiscoverSvcURL, summaryURL, collected)
			}
			return c.SendString(result.String())
		}

		return c.SendStream(resp.Body)
	})

	port := cfg.ChatSvcPort
	log.Printf("chat-svc listening on :%d", port)
	log.Fatal(app.Listen(fmt.Sprintf(":%d", port)))
}

func init() {
	if os.Getenv("PORT") == "" {
		os.Setenv("PORT", "3005")
	}
}

func saveArticleSummary(discoverSvcURL, articleURL string, events []string) {
	if discoverSvcURL == "" || articleURL == "" || len(events) == 0 {
		return
	}

	payload := map[string]interface{}{
		"url":    articleURL,
		"events": events,
	}

	body, err := json.Marshal(payload)
	if err != nil {
		log.Printf("article-summary marshal error: %v", err)
		return
	}

	url := strings.TrimSuffix(discoverSvcURL, "/") + "/api/v1/discover/article-summary"

	maxRetries := 5
	retryDelay := 2 * time.Second

	for attempt := 1; attempt <= maxRetries; attempt++ {
		req, err := http.NewRequest("POST", url, bytes.NewReader(body))
		if err != nil {
			log.Printf("article-summary request error (attempt %d): %v", attempt, err)
			continue
		}
		req.Header.Set("Content-Type", "application/json")

		client := &http.Client{Timeout: 2 * time.Minute}
		resp, err := client.Do(req)
		if err != nil {
			log.Printf("article-summary save error (attempt %d): %v", attempt, err)
			if attempt < maxRetries {
				time.Sleep(retryDelay)
			}
			continue
		}
		resp.Body.Close()

		if resp.StatusCode >= 200 && resp.StatusCode < 300 {
			log.Printf("article-summary saved: %s", articleURL[:min(60, len(articleURL))])
			return
		}

		log.Printf("article-summary save failed (attempt %d): status %d", attempt, resp.StatusCode)
		if attempt < maxRetries {
			time.Sleep(retryDelay)
		}
	}

	log.Printf("article-summary save failed after %d retries: %s", maxRetries, articleURL[:min(60, len(articleURL))])
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}