package middleware

import (
	"context"
	"database/sql"

	"github.com/gofiber/fiber/v2"
	"github.com/gooseek/backend/internal/usage"
	"github.com/gooseek/backend/pkg/metrics"
)

type LLMLimitsConfig struct {
	UsageRepo *usage.Repository
}

func LLMLimits(config LLMLimitsConfig) fiber.Handler {
	return func(c *fiber.Ctx) error {
		userID := GetUserID(c)
		clientIP := c.IP()

		if userID == "" {
			metrics.RecordLLMUnauthorized("no_user_id", clientIP)
			metrics.RecordSecurityEvent("unauthorized_llm_access", clientIP, "anonymous")
			return c.Status(401).JSON(fiber.Map{
				"error": "Authentication required",
			})
		}

		tier := GetUserTier(c)
		if tier == "" {
			tier = "free"
		}

		if config.UsageRepo != nil {
			allowed, reason := config.UsageRepo.CheckLLMLimits(c.Context(), userID, tier)
			if !allowed {
				limits := usage.GetLimits(tier)

				if tier == "free" {
					metrics.RecordFreeTierLimitExceeded(userID, reason)
					metrics.RecordSecurityEvent("free_tier_limit_exceeded", clientIP, userID)
				}
				metrics.RecordRateLimitHit("llm-svc", clientIP, reason)

				return c.Status(429).JSON(fiber.Map{
					"error":        reason,
					"tier":         tier,
					"dailyLimit":   limits.LLMRequestsPerDay,
					"tokenLimit":   limits.LLMTokensPerDay,
					"upgradeUrl":   "/settings/billing",
				})
			}
		}

		return c.Next()
	}
}

type UsageTracker struct {
	repo *usage.Repository
}

func NewUsageTracker(db *sql.DB) *UsageTracker {
	return &UsageTracker{
		repo: usage.NewRepository(db),
	}
}

func (t *UsageTracker) RunMigrations(ctx context.Context) error {
	return t.repo.RunMigrations(ctx)
}

func (t *UsageTracker) TrackAPIRequest(c *fiber.Ctx) {
	userID := GetUserID(c)
	if userID == "" {
		return
	}
	tier := GetUserTier(c)
	if tier == "" {
		tier = "free"
	}
	go t.repo.IncrementAPIRequests(context.Background(), userID, tier)
}

func (t *UsageTracker) TrackLLMRequest(ctx context.Context, userID, tier string, tokens int) {
	if userID == "" {
		return
	}
	if tier == "" {
		tier = "free"
	}
	go t.repo.IncrementLLMUsage(ctx, userID, tier, tokens)
}

func (t *UsageTracker) TrackSearchRequest(c *fiber.Ctx) {
	userID := GetUserID(c)
	if userID == "" {
		return
	}
	tier := GetUserTier(c)
	if tier == "" {
		tier = "free"
	}
	go t.repo.IncrementSearchRequests(context.Background(), userID, tier)
}

func (t *UsageTracker) GetRepository() *usage.Repository {
	return t.repo
}

func UsageTracking(tracker *UsageTracker) fiber.Handler {
	return func(c *fiber.Ctx) error {
		if tracker != nil {
			tracker.TrackAPIRequest(c)
		}
		return c.Next()
	}
}