package main

import (
	"bufio"
	"context"
	"database/sql"
	"fmt"
	"log"
	"os"
	"time"

	"github.com/gofiber/fiber/v2"
	"github.com/gofiber/fiber/v2/middleware/cors"
	"github.com/gofiber/fiber/v2/middleware/logger"
	"github.com/gooseek/backend/internal/llm"
	"github.com/gooseek/backend/internal/usage"
	"github.com/gooseek/backend/pkg/config"
	"github.com/gooseek/backend/pkg/email"
	"github.com/gooseek/backend/pkg/metrics"
	"github.com/gooseek/backend/pkg/middleware"
	"github.com/gooseek/backend/pkg/ndjson"
	_ "github.com/lib/pq"
)

type GenerateRequest struct {
	ProviderID string `json:"providerId"`
	ModelKey   string `json:"key"`
	Messages   []struct {
		Role    string `json:"role"`
		Content string `json:"content"`
	} `json:"messages"`
	Options struct {
		MaxTokens   int     `json:"maxTokens"`
		Temperature float64 `json:"temperature"`
		Stream      bool    `json:"stream"`
	} `json:"options"`
}

type EmbedRequest struct {
	Input string `json:"input"`
	Model string `json:"model,omitempty"`
}

type ProviderRouting struct {
	ProviderID string
	ModelKey   string
}

func resolveProvider(cfg *config.Config, tier string, requestedProvider string, requestedModel string) ProviderRouting {
	if tier == "free" || tier == "" {
		return ProviderRouting{
			ProviderID: "ollama",
			ModelKey:   cfg.OllamaModelKey,
		}
	}

	if requestedProvider != "" && requestedProvider != "auto" {
		return ProviderRouting{
			ProviderID: requestedProvider,
			ModelKey:   requestedModel,
		}
	}

	if cfg.TimewebAgentAccessID != "" && cfg.TimewebAPIKey != "" {
		return ProviderRouting{
			ProviderID: "timeweb",
			ModelKey:   requestedModel,
		}
	}

	if cfg.OpenAIAPIKey != "" {
		return ProviderRouting{
			ProviderID: "openai",
			ModelKey:   "gpt-4o-mini",
		}
	}

	return ProviderRouting{
		ProviderID: "ollama",
		ModelKey:   cfg.OllamaModelKey,
	}
}

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

	var usageRepo *usage.Repository
	if cfg.DatabaseURL != "" {
		db, err := sql.Open("postgres", cfg.DatabaseURL)
		if err != nil {
			log.Printf("Usage tracking unavailable: %v", err)
		} else {
			db.SetMaxOpenConns(5)
			db.SetMaxIdleConns(2)
			defer db.Close()

			usageRepo = usage.NewRepository(db)
			ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
			if err := usageRepo.RunMigrations(ctx); err != nil {
				log.Printf("Usage migrations warning: %v", err)
			}
			cancel()
			log.Println("Usage tracking enabled")
		}
	}

	app := fiber.New(fiber.Config{
		StreamRequestBody: true,
		BodyLimit:         10 * 1024 * 1024,
		ReadTimeout:       time.Minute,
		WriteTimeout:      5 * time.Minute,
		IdleTimeout:       2 * time.Minute,
	})

	app.Use(logger.New())
	app.Use(cors.New())
	app.Use(metrics.PrometheusMiddleware(metrics.MetricsConfig{
		ServiceName: "llm-svc",
	}))

	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", metrics.MetricsHandler())

	app.Get("/api/v1/providers", func(c *fiber.Ctx) error {
		providers := []fiber.Map{}

		providers = append(providers, fiber.Map{
			"id":       "ollama",
			"name":     "GooSeek AI (Бесплатно)",
			"models":   []string{cfg.OllamaModelKey},
			"tier":     "free",
			"isLocal":  true,
		})

		if cfg.TimewebAgentAccessID != "" && cfg.TimewebAPIKey != "" {
			providers = append(providers, fiber.Map{
				"id":     "timeweb",
				"name":   "Timeweb Cloud AI (Pro)",
				"models": []string{"gpt-4o", "gpt-4o-mini", "claude-3-5-sonnet", "gemini-1.5-pro"},
				"tier":   "pro",
			})
		}

		if cfg.OpenAIAPIKey != "" {
			providers = append(providers, fiber.Map{
				"id":     "openai",
				"name":   "OpenAI",
				"models": []string{"gpt-4o", "gpt-4o-mini", "gpt-4-turbo"},
				"tier":   "pro",
			})
		}

		if cfg.AnthropicAPIKey != "" {
			providers = append(providers, fiber.Map{
				"id":     "anthropic",
				"name":   "Anthropic",
				"models": []string{"claude-3-5-sonnet-20241022", "claude-3-opus-20240229"},
				"tier":   "pro",
			})
		}

		if cfg.GeminiAPIKey != "" {
			providers = append(providers, fiber.Map{
				"id":     "gemini",
				"name":   "Google Gemini",
				"models": []string{"gemini-1.5-pro", "gemini-1.5-flash", "gemini-2.0-flash-exp"},
				"tier":   "pro",
			})
		}

		return c.JSON(fiber.Map{
			"providers":   providers,
			"envOnlyMode": true,
		})
	})

	app.Get("/api/v1/providers/ui-config", func(c *fiber.Ctx) error {
		return c.JSON(fiber.Map{
			"sections": []interface{}{},
		})
	})

	emailSender := email.NewSender(email.SMTPConfig{
		Host:     cfg.SMTPHost,
		Port:     cfg.SMTPPort,
		User:     cfg.SMTPUser,
		Password: cfg.SMTPPassword,
		From:     cfg.SMTPFrom,
		TLS:      cfg.SMTPTLS,
		SiteURL:  cfg.SiteURL,
		SiteName: cfg.SiteName,
	})

	llmAPI := app.Group("/api/v1", middleware.JWT(middleware.JWTConfig{
		Secret:     cfg.JWTSecret,
		AuthSvcURL: cfg.AuthSvcURL,
		AllowGuest: false,
	}), middleware.LLMLimits(middleware.LLMLimitsConfig{
		UsageRepo:   usageRepo,
		EmailSender: emailSender,
	}))

	llmAPI.Post("/generate", func(c *fiber.Ctx) error {
		startTime := time.Now()
		userID := middleware.GetUserID(c)
		tier := middleware.GetUserTier(c)
		clientIP := c.IP()

		if tier == "" {
			tier = "free"
		}

		var req GenerateRequest
		if err := c.BodyParser(&req); err != nil {
			metrics.RecordLLMError(req.ProviderID, "invalid_request")
			return c.Status(400).JSON(fiber.Map{"error": "Invalid request body"})
		}

		if len(req.Messages) == 0 {
			metrics.RecordLLMError(req.ProviderID, "empty_messages")
			return c.Status(400).JSON(fiber.Map{"error": "Messages required"})
		}

		limits := usage.GetLimits(tier)
		if req.Options.MaxTokens == 0 || req.Options.MaxTokens > limits.MaxTokensPerReq {
			if tier == "free" && req.Options.MaxTokens > limits.MaxTokensPerReq {
				metrics.RecordFreeTierLimitExceeded(userID, "max_tokens")
			}
			req.Options.MaxTokens = limits.MaxTokensPerReq
		}

		routing := resolveProvider(cfg, tier, req.ProviderID, req.ModelKey)
		providerID := routing.ProviderID
		modelKey := routing.ModelKey

		metrics.RecordLLMRequest(providerID, modelKey, tier, userID)

		client, err := llm.NewClient(llm.ProviderConfig{
			ProviderID:    providerID,
			ModelKey:      modelKey,
			APIKey:        getAPIKey(cfg, providerID),
			BaseURL:       getBaseURL(cfg, providerID),
			AgentAccessID: cfg.TimewebAgentAccessID,
		})
		if err != nil {
			metrics.RecordLLMError(req.ProviderID, "client_init_error")
			return c.Status(500).JSON(fiber.Map{"error": err.Error()})
		}

		messages := make([]llm.Message, len(req.Messages))
		for i, m := range req.Messages {
			messages[i] = llm.Message{
				Role:    llm.Role(m.Role),
				Content: m.Content,
			}
		}

		ctx, cancel := context.WithTimeout(context.Background(), cfg.LLMTimeout)
		defer cancel()

		if req.Options.Stream {
			stream, err := client.StreamText(ctx, llm.StreamRequest{
				Messages: messages,
				Options: llm.StreamOptions{
					MaxTokens:   req.Options.MaxTokens,
					Temperature: req.Options.Temperature,
				},
			})
			if err != nil {
				metrics.RecordLLMError(providerID, "stream_error")
				metrics.RecordSecurityEvent("llm_error", clientIP, userID)
				return c.Status(500).JSON(fiber.Map{"error": err.Error()})
			}

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

			c.Context().SetBodyStreamWriter(func(w *bufio.Writer) {
				writer := ndjson.NewWriter(w)
				tokenCount := 0
				for chunk := range stream {
					writer.Write(fiber.Map{
						"type":  "chunk",
						"chunk": chunk.ContentChunk,
					})
					w.Flush()
					tokenCount += len(chunk.ContentChunk) / 4
				}
				writer.Write(fiber.Map{"type": "done"})

				metrics.RecordLLMLatency(providerID, modelKey, time.Since(startTime))
				metrics.RecordLLMTokens(providerID, tier, userID, tokenCount)

				if usageRepo != nil {
					go usageRepo.IncrementLLMUsage(context.Background(), userID, tier, tokenCount)
				}
			})

			return nil
		}

		response, err := client.GenerateText(ctx, llm.StreamRequest{
			Messages: messages,
			Options: llm.StreamOptions{
				MaxTokens:   req.Options.MaxTokens,
				Temperature: req.Options.Temperature,
			},
		})
		if err != nil {
			metrics.RecordLLMError(providerID, "generate_error")
			return c.Status(500).JSON(fiber.Map{"error": err.Error()})
		}

		tokenCount := len(response) / 4
		metrics.RecordLLMLatency(providerID, modelKey, time.Since(startTime))
		metrics.RecordLLMTokens(providerID, tier, userID, tokenCount)

		if usageRepo != nil {
			go usageRepo.IncrementLLMUsage(context.Background(), userID, tier, tokenCount)
		}

		return c.JSON(fiber.Map{
			"content": response,
		})
	})

	llmAPI.Post("/embed", func(c *fiber.Ctx) error {
		userID := middleware.GetUserID(c)
		tier := middleware.GetUserTier(c)

		if tier == "" {
			tier = "free"
		}

		var req EmbedRequest
		if err := c.BodyParser(&req); err != nil {
			return c.Status(400).JSON(fiber.Map{"error": "Invalid request body"})
		}

		if req.Input == "" {
			return c.Status(400).JSON(fiber.Map{"error": "Input text required"})
		}

		model := req.Model
		if model == "" {
			model = cfg.OllamaEmbeddingModel
		}

		embeddings, err := llm.GenerateEmbedding(cfg.OllamaBaseURL, model, req.Input)
		if err != nil {
			metrics.RecordLLMError("ollama", "embed_error")
			return c.Status(500).JSON(fiber.Map{"error": err.Error()})
		}

		metrics.RecordLLMRequest("ollama", model, tier, userID)

		return c.JSON(fiber.Map{
			"embedding": embeddings,
			"model":     model,
		})
	})

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

func getAPIKey(cfg *config.Config, providerID string) string {
	switch providerID {
	case "openai":
		return cfg.OpenAIAPIKey
	case "timeweb":
		return cfg.TimewebAPIKey
	case "anthropic":
		return cfg.AnthropicAPIKey
	case "gemini", "google":
		return cfg.GeminiAPIKey
	default:
		return ""
	}
}

func getBaseURL(cfg *config.Config, providerID string) string {
	switch providerID {
	case "timeweb":
		return cfg.TimewebAPIBaseURL
	case "ollama":
		return cfg.OllamaBaseURL
	default:
		return ""
	}
}

func init() {
	if os.Getenv("PORT") == "" {
		os.Setenv("PORT", "3020")
	}
}