package main

import (
	"context"
	"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/learning"
	"github.com/gooseek/backend/internal/llm"
	"github.com/gooseek/backend/pkg/config"
)

type LessonStore struct {
	lessons map[string]*learning.StepByStepLesson
}

func NewLessonStore() *LessonStore {
	return &LessonStore{
		lessons: make(map[string]*learning.StepByStepLesson),
	}
}

func (s *LessonStore) Save(lesson *learning.StepByStepLesson) {
	s.lessons[lesson.ID] = lesson
}

func (s *LessonStore) Get(id string) *learning.StepByStepLesson {
	return s.lessons[id]
}

func (s *LessonStore) List(limit, offset int) []*learning.StepByStepLesson {
	result := make([]*learning.StepByStepLesson, 0)
	i := 0
	for _, l := range s.lessons {
		if i >= offset && len(result) < limit {
			result = append(result, l)
		}
		i++
	}
	return result
}

func (s *LessonStore) Delete(id string) bool {
	if _, ok := s.lessons[id]; ok {
		delete(s.lessons, id)
		return true
	}
	return false
}

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

	var llmClient llm.Client

	// Priority 1: Timeweb Cloud AI (recommended for production)
	if cfg.TimewebAgentAccessID != "" && cfg.TimewebAPIKey != "" {
		client, err := llm.NewTimewebClient(llm.TimewebConfig{
			ProviderID:    "timeweb",
			BaseURL:       cfg.TimewebAPIBaseURL,
			AgentAccessID: cfg.TimewebAgentAccessID,
			APIKey:        cfg.TimewebAPIKey,
			ModelKey:      cfg.DefaultLLMModel,
			ProxySource:   cfg.TimewebProxySource,
		})
		if err != nil {
			log.Printf("Warning: Failed to create Timeweb client: %v", err)
		} else {
			llmClient = client
			log.Println("Using Timeweb Cloud AI as LLM provider")
		}
	}

	// Priority 2: Anthropic
	if llmClient == nil && cfg.AnthropicAPIKey != "" && !isJWT(cfg.AnthropicAPIKey) {
		client, err := llm.NewAnthropicClient(llm.ProviderConfig{
			ProviderID: "anthropic",
			APIKey:     cfg.AnthropicAPIKey,
			ModelKey:   "claude-3-5-sonnet-20241022",
		})
		if err != nil {
			log.Printf("Warning: Failed to create Anthropic client: %v", err)
		} else {
			llmClient = client
			log.Println("Using Anthropic as LLM provider")
		}
	}

	// Priority 3: OpenAI (only if it's a real OpenAI key, not Timeweb JWT)
	if llmClient == nil && cfg.OpenAIAPIKey != "" && !isJWT(cfg.OpenAIAPIKey) {
		client, err := llm.NewOpenAIClient(llm.ProviderConfig{
			ProviderID: "openai",
			APIKey:     cfg.OpenAIAPIKey,
			ModelKey:   "gpt-4o-mini",
		})
		if err != nil {
			log.Printf("Warning: Failed to create OpenAI client: %v", err)
		} else {
			llmClient = client
			log.Println("Using OpenAI as LLM provider")
		}
	}

	if llmClient == nil {
		log.Fatal("No LLM provider configured. Please set TIMEWEB_AGENT_ACCESS_ID + TIMEWEB_API_KEY, or OPENAI_API_KEY, or ANTHROPIC_API_KEY")
	}

	generator := learning.NewLearningGenerator(llmClient)
	store := NewLessonStore()

	app := fiber.New(fiber.Config{
		BodyLimit:    50 * 1024 * 1024,
		ReadTimeout:  120 * time.Second,
		WriteTimeout: 120 * time.Second,
	})

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

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

	app.Post("/api/v1/learning/lesson", func(c *fiber.Ctx) error {
		var req struct {
			Topic       string `json:"topic"`
			Query       string `json:"query"`
			Difficulty  string `json:"difficulty"`
			Mode        string `json:"mode"`
			MaxSteps    int    `json:"maxSteps"`
			Locale      string `json:"locale"`
			IncludeCode bool   `json:"includeCode"`
			IncludeQuiz bool   `json:"includeQuiz"`
		}

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

		ctx, cancel := context.WithTimeout(context.Background(), 120*time.Second)
		defer cancel()

		difficulty := learning.DifficultyBeginner
		switch req.Difficulty {
		case "intermediate":
			difficulty = learning.DifficultyIntermediate
		case "advanced":
			difficulty = learning.DifficultyAdvanced
		case "expert":
			difficulty = learning.DifficultyExpert
		}

		mode := learning.ModeExplain
		switch req.Mode {
		case "guided":
			mode = learning.ModeGuided
		case "interactive":
			mode = learning.ModeInteractive
		case "practice":
			mode = learning.ModePractice
		case "quiz":
			mode = learning.ModeQuiz
		}

		lesson, err := generator.GenerateLesson(ctx, learning.GenerateLessonOptions{
			Topic:       req.Topic,
			Query:       req.Query,
			Difficulty:  difficulty,
			Mode:        mode,
			MaxSteps:    req.MaxSteps,
			Locale:      req.Locale,
			IncludeCode: req.IncludeCode,
			IncludeQuiz: req.IncludeQuiz,
		})
		if err != nil {
			return c.Status(500).JSON(fiber.Map{"error": err.Error()})
		}

		store.Save(lesson)

		return c.JSON(lesson)
	})

	app.Post("/api/v1/learning/explain", func(c *fiber.Ctx) error {
		var req struct {
			Topic      string `json:"topic"`
			Difficulty string `json:"difficulty"`
			Locale     string `json:"locale"`
		}

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

		ctx, cancel := context.WithTimeout(context.Background(), 60*time.Second)
		defer cancel()

		difficulty := learning.DifficultyBeginner
		switch req.Difficulty {
		case "intermediate":
			difficulty = learning.DifficultyIntermediate
		case "advanced":
			difficulty = learning.DifficultyAdvanced
		case "expert":
			difficulty = learning.DifficultyExpert
		}

		step, err := generator.GenerateExplanation(ctx, req.Topic, difficulty, req.Locale)
		if err != nil {
			return c.Status(500).JSON(fiber.Map{"error": err.Error()})
		}

		return c.JSON(step)
	})

	app.Post("/api/v1/learning/quiz", func(c *fiber.Ctx) error {
		var req struct {
			Topic        string `json:"topic"`
			NumQuestions int    `json:"numQuestions"`
			Difficulty   string `json:"difficulty"`
			Locale       string `json:"locale"`
		}

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

		if req.NumQuestions == 0 {
			req.NumQuestions = 5
		}

		ctx, cancel := context.WithTimeout(context.Background(), 60*time.Second)
		defer cancel()

		difficulty := learning.DifficultyBeginner
		switch req.Difficulty {
		case "intermediate":
			difficulty = learning.DifficultyIntermediate
		case "advanced":
			difficulty = learning.DifficultyAdvanced
		case "expert":
			difficulty = learning.DifficultyExpert
		}

		questions, err := generator.GenerateQuiz(ctx, req.Topic, req.NumQuestions, difficulty, req.Locale)
		if err != nil {
			return c.Status(500).JSON(fiber.Map{"error": err.Error()})
		}

		return c.JSON(fiber.Map{"questions": questions})
	})

	app.Post("/api/v1/learning/practice", func(c *fiber.Ctx) error {
		var req struct {
			Topic      string `json:"topic"`
			Language   string `json:"language"`
			Difficulty string `json:"difficulty"`
			Locale     string `json:"locale"`
		}

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

		ctx, cancel := context.WithTimeout(context.Background(), 60*time.Second)
		defer cancel()

		difficulty := learning.DifficultyBeginner
		switch req.Difficulty {
		case "intermediate":
			difficulty = learning.DifficultyIntermediate
		case "advanced":
			difficulty = learning.DifficultyAdvanced
		case "expert":
			difficulty = learning.DifficultyExpert
		}

		exercise, err := generator.GeneratePracticeExercise(ctx, req.Topic, req.Language, difficulty, req.Locale)
		if err != nil {
			return c.Status(500).JSON(fiber.Map{"error": err.Error()})
		}

		return c.JSON(exercise)
	})

	app.Get("/api/v1/learning/lessons", func(c *fiber.Ctx) error {
		limit := c.QueryInt("limit", 20)
		offset := c.QueryInt("offset", 0)

		lessons := store.List(limit, offset)

		summaries := make([]map[string]interface{}, 0)
		for _, l := range lessons {
			summaries = append(summaries, map[string]interface{}{
				"id":            l.ID,
				"title":         l.Title,
				"topic":         l.Topic,
				"difficulty":    l.Difficulty,
				"mode":          l.Mode,
				"stepsCount":    len(l.Steps),
				"estimatedTime": l.EstimatedTime,
				"progress":      l.Progress,
				"createdAt":     l.CreatedAt,
			})
		}

		return c.JSON(fiber.Map{"lessons": summaries, "count": len(summaries)})
	})

	app.Get("/api/v1/learning/lessons/:id", func(c *fiber.Ctx) error {
		id := c.Params("id")
		lesson := store.Get(id)
		if lesson == nil {
			return c.Status(404).JSON(fiber.Map{"error": "Lesson not found"})
		}
		return c.JSON(lesson)
	})

	app.Post("/api/v1/learning/lessons/:id/complete-step", func(c *fiber.Ctx) error {
		id := c.Params("id")
		lesson := store.Get(id)
		if lesson == nil {
			return c.Status(404).JSON(fiber.Map{"error": "Lesson not found"})
		}

		var req struct {
			StepIndex int `json:"stepIndex"`
		}

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

		lesson.CompleteStep(req.StepIndex)

		return c.JSON(fiber.Map{
			"success":  true,
			"progress": lesson.Progress,
		})
	})

	app.Post("/api/v1/learning/lessons/:id/submit-answer", func(c *fiber.Ctx) error {
		id := c.Params("id")
		lesson := store.Get(id)
		if lesson == nil {
			return c.Status(404).JSON(fiber.Map{"error": "Lesson not found"})
		}

		var req struct {
			StepIndex       int      `json:"stepIndex"`
			SelectedOptions []string `json:"selectedOptions"`
		}

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

		correct, explanation := lesson.SubmitQuizAnswer(req.StepIndex, req.SelectedOptions)

		if correct {
			lesson.CompleteStep(req.StepIndex)
		}

		return c.JSON(fiber.Map{
			"correct":     correct,
			"explanation": explanation,
			"progress":    lesson.Progress,
		})
	})

	app.Delete("/api/v1/learning/lessons/:id", func(c *fiber.Ctx) error {
		id := c.Params("id")
		if store.Delete(id) {
			return c.JSON(fiber.Map{"success": true})
		}
		return c.Status(404).JSON(fiber.Map{"error": "Lesson not found"})
	})

	port := getEnvInt("LEARNING_SVC_PORT", 3034)
	log.Printf("learning-svc listening on :%d", port)
	log.Fatal(app.Listen(fmt.Sprintf(":%d", port)))
}

func getEnvInt(key string, defaultValue int) int {
	if val := os.Getenv(key); val != "" {
		var result int
		if _, err := fmt.Sscanf(val, "%d", &result); err == nil {
			return result
		}
	}
	return defaultValue
}

func isJWT(s string) bool {
	return len(s) > 10 && s[:3] == "eyJ"
}