package main

import (
	"fmt"
	"strconv"
	"time"

	"github.com/goccy/go-json"
	fiber "github.com/gofiber/fiber/v2"
	"github.com/gofiber/fiber/v2/middleware/cors"
	"github.com/google/uuid"

	libpack_config "github.com/lukaszraczylo/graphql-monitoring-proxy/config"
	libpack_monitoring "github.com/lukaszraczylo/graphql-monitoring-proxy/monitoring"
)

// StartHTTPProxy starts the HTTP and points it to the GraphQL server.
func StartHTTPProxy() {
	server := fiber.New(fiber.Config{
		DisableStartupMessage: true,
		AppName:               fmt.Sprintf("GraphQL Monitoring Proxy - %s v%s", libpack_config.PKG_NAME, libpack_config.PKG_VERSION),
		IdleTimeout:           time.Duration(cfg.Client.ClientTimeout) * time.Second * 2,
		ReadTimeout:           time.Duration(cfg.Client.ClientTimeout) * time.Second * 2,
		WriteTimeout:          time.Duration(cfg.Client.ClientTimeout) * time.Second * 2,
		JSONEncoder:           json.Marshal,
		JSONDecoder:           json.Unmarshal,
	})

	server.Use(cors.New(cors.Config{
		AllowOrigins: "*",
	}))

	// add middleware to check if the request is a GraphQL query
	server.Use(AddRequestUUID)

	server.Get("/healthz", healthCheck)
	server.Get("/livez", healthCheck)

	server.Post("/*", processGraphQLRequest)
	server.Get("/*", proxyTheRequest)

	cfg.Logger.Info("GraphQL query proxy started", map[string]interface{}{"port": cfg.Server.PortGraphQL})
	err := server.Listen(fmt.Sprintf(":%d", cfg.Server.PortGraphQL))
	if err != nil {
		cfg.Logger.Critical("Can't start the service", map[string]interface{}{"error": err.Error()})
	}
}

func AddRequestUUID(c *fiber.Ctx) error {
	c.Locals("request_uuid", uuid.NewString())
	return c.Next()
}

func checkAllowedURLs(c *fiber.Ctx) bool {
	if len(allowedUrls) == 0 {
		return true
	}
	_, ok := allowedUrls[c.Path()]
	return ok
}

func healthCheck(c *fiber.Ctx) error {
	if len(cfg.Server.HealthcheckGraphQL) > 0 {
		cfg.Logger.Debug("Health check enabled", map[string]interface{}{"url": cfg.Server.HealthcheckGraphQL})
		query := `{ __typename }`
		_, err := cfg.Client.GQLClient.Query(query, nil, nil)
		if err != nil {
			cfg.Logger.Error("Can't reach the GraphQL server", map[string]interface{}{"error": err.Error()})
			cfg.Monitoring.Increment(libpack_monitoring.MetricsFailed, nil)
			c.Status(500).SendString("Can't reach the GraphQL server with {__typename} query")
			return err
		}
	}
	cfg.Logger.Debug("Health check returning OK")
	c.Status(200).SendString("Health check OK")
	return nil
}

func processGraphQLRequest(c *fiber.Ctx) error {
	startTime := time.Now()

	// Initialize variables with default values
	extractedUserID := "-"
	extractedRoleName := "-"
	var queryCacheHash string

	authorization := c.Request().Header.Peek("Authorization")
	if authorization != nil && (len(cfg.Client.JWTUserClaimPath) > 0 || len(cfg.Client.JWTRoleClaimPath) > 0) {
		extractedUserID, extractedRoleName = extractClaimsFromJWTHeader(string(authorization))
	}

	if checkIfUserIsBanned(c, extractedUserID) {
		return nil
	}

	if len(cfg.Client.RoleFromHeader) > 0 {
		extractedRoleName = string(c.Request().Header.Peek(cfg.Client.RoleFromHeader))
		if extractedRoleName == "" {
			extractedRoleName = "-"
		}
	}

	// Implementing rate limiting if enabled
	if cfg.Client.RoleRateLimit {
		cfg.Logger.Debug("Rate limiting enabled", map[string]interface{}{"user_id": extractedUserID, "role_name": extractedRoleName})
		if !rateLimitedRequest(extractedUserID, extractedRoleName) {
			c.Status(429).SendString("Rate limit exceeded, try again later")
			return nil
		}
	}

	opType, opName, cacheFromQuery, cache_time, shouldBlock, should_ignore := parseGraphQLQuery(c)
	if shouldBlock {
		return nil
	}

	if should_ignore {
		cfg.Logger.Debug("Request passed as-is - probably not a GraphQL")
		return proxyTheRequest(c)
	}

	if cache_time > 0 {
		cfg.Logger.Debug("Cache time set via query", map[string]interface{}{"cache_time": cache_time})
	} else {
		// If not set via query, try setting via header
		cacheQuery := c.Request().Header.Peek("X-Cache-Graphql-Query")
		if cacheQuery != nil {
			cache_time, _ = strconv.Atoi(string(cacheQuery))
			cfg.Logger.Debug("Cache time set via header", map[string]interface{}{"cache_time": cache_time})
		} else {
			cache_time = cfg.Cache.CacheTTL
		}
	}

	wasCached := false

	// Handling Cache Logic
	if cacheFromQuery || cfg.Cache.CacheEnable {
		cfg.Logger.Debug("Cache enabled", map[string]interface{}{"via_query": cacheFromQuery, "via_env": cfg.Cache.CacheEnable})
		queryCacheHash = calculateHash(c)

		if cachedResponse := cacheLookup(queryCacheHash); cachedResponse != nil {
			cfg.Logger.Debug("Cache hit", map[string]interface{}{"hash": queryCacheHash, "user_id": extractedUserID, "request_uuid": c.Locals("request_uuid")})
			c.Send(cachedResponse)
			wasCached = true
		} else {
			cfg.Logger.Debug("Cache miss", map[string]interface{}{"hash": queryCacheHash, "user_id": extractedUserID, "request_uuid": c.Locals("request_uuid")})
			proxyAndCacheTheRequest(c, queryCacheHash, cache_time)
		}
	} else {
		proxyTheRequest(c)
	}

	timeTaken := time.Since(startTime)

	// Logging & Monitoring
	logAndMonitorRequest(c, extractedUserID, opType, opName, wasCached, timeTaken, startTime)

	return nil
}

// Additional helper function to avoid code repetition
func proxyAndCacheTheRequest(c *fiber.Ctx, queryCacheHash string, cache_time int) {
	err := proxyTheRequest(c)
	if err != nil {
		cfg.Logger.Error("Can't proxy the request", map[string]interface{}{"error": err.Error()})
		cfg.Monitoring.Increment(libpack_monitoring.MetricsFailed, nil)
		c.Status(500).SendString("Can't proxy the request - try again later")
		return
	}
	cfg.Cache.CacheClient.Set(queryCacheHash, c.Response().Body(), time.Duration(cache_time)*time.Second)
	c.Send(c.Response().Body())
}

func logAndMonitorRequest(c *fiber.Ctx, userID, opType, opName string, wasCached bool, duration time.Duration, startTime time.Time) {
	labels := map[string]string{
		"op_type": opType,
		"op_name": opName,
		"cached":  fmt.Sprintf("%t", wasCached),
		"user_id": userID,
	}

	if cfg.Server.AccessLog {
		cfg.Logger.Info("Request processed", map[string]interface{}{
			"ip":           c.IP(),
			"fwd-ip":       string(c.Request().Header.Peek("X-Forwarded-For")),
			"user_id":      userID,
			"op_type":      opType,
			"op_name":      opName,
			"time":         duration,
			"cache":        wasCached,
			"request_uuid": c.Locals("request_uuid"),
		})
	}

	cfg.Monitoring.Increment(libpack_monitoring.MetricsSucceeded, nil)
	cfg.Monitoring.Increment("executed_query", labels)

	if !wasCached {
		cfg.Monitoring.UpdateDuration("timed_query", labels, startTime)
		cfg.Monitoring.Update("timed_query", labels, float64(duration.Milliseconds()))
	}
}