package web

import (
	"bufio"
	"embed"
	"encoding/gob"
	"errors"
	"fmt"
	"github.com/a-h/templ"
	"github.com/go-webauthn/webauthn/webauthn"
	"github.com/goccy/go-json"
	"github.com/gofiber/fiber/v2"
	"github.com/gofiber/fiber/v2/log"
	"github.com/gofiber/fiber/v2/middleware/earlydata"
	"github.com/gofiber/fiber/v2/middleware/etag"
	"github.com/gofiber/fiber/v2/middleware/filesystem"
	"github.com/gofiber/fiber/v2/middleware/healthcheck"
	"github.com/gofiber/fiber/v2/middleware/helmet"
	"github.com/gofiber/fiber/v2/middleware/limiter"
	"github.com/gofiber/fiber/v2/middleware/recover"
	"github.com/gofiber/fiber/v2/middleware/session"
	"github.com/gofiber/storage/postgres/v3"
	"github.com/jackc/pgx/v5/pgxpool"
	"github.com/spf13/viper"
	"github.com/uptrace/bun"
	"go.uber.org/zap"
	"net/http"
	"net/url"
	"omnibill.net/omnibill/web/utils"
	"omnibill.net/omnibill/web/views/layouts"
	"reflect"
	"strings"
	"time"
)

//go:embed assets/**/*
var assetDir embed.FS

func Start(logger *zap.Logger, db *bun.DB, dbPool *pgxpool.Pool) {

	panelURL, err := url.Parse(viper.GetString("omnibill.domain"))
	if err != nil {
		logger.Fatal("error parsing panel URL", zap.Error(err))
	}

	gob.Register(&webauthn.SessionData{})
	webAuthnConfig := &webauthn.Config{
		RPDisplayName: viper.GetString("omnibill.display_name"),
		RPID:          panelURL.Host,
		RPOrigins:     []string{panelURL.String()},
	}

	webAuthn, err := webauthn.New(webAuthnConfig)
	if err != nil {
		logger.Fatal("error creating webauthn", zap.Error(err))
	}

	appConfig := fiber.Config{
		AppName:     viper.GetString("omnibill.display_name"),
		JSONEncoder: json.Marshal,
		JSONDecoder: json.Unmarshal,
	}

	if len(viper.GetString("omnibill.webserver.proxy")) != 0 {
		switch strings.ToLower(viper.GetString("omnibill.webserver.proxy")) {
		case "cloudflare", "cf":
			logger.Info("grabbing trusted proxy list")

			var trustedProxies []string

			v4Req, err := http.NewRequest("GET", "https://www.cloudflare.com/ips-v4/#", nil)
			if err != nil {
				logger.Fatal("error creating request", zap.Error(err))
			}

			v6Req, err := http.NewRequest("GET", "https://www.cloudflare.com/ips-v6/#", nil)
			if err != nil {
				logger.Fatal("error creating request", zap.Error(err))
			}

			client := &http.Client{}

			v4Resp, err := client.Do(v4Req)
			if err != nil {
				logger.Fatal("error doing request", zap.Error(err))
			}
			defer v4Resp.Body.Close()

			v4Scanner := bufio.NewScanner(v4Resp.Body)
			v4Scanner.Split(bufio.ScanLines)

			for v4Scanner.Scan() {
				trustedProxies = append(trustedProxies, v4Scanner.Text())
			}

			v6Resp, err := client.Do(v6Req)
			if err != nil {
				logger.Fatal("error doing request", zap.Error(err))
			}
			defer v6Resp.Body.Close()

			v6Scanner := bufio.NewScanner(v6Resp.Body)
			v6Scanner.Split(bufio.ScanLines)

			for v6Scanner.Scan() {
				trustedProxies = append(trustedProxies, v6Scanner.Text())
			}

			appConfig.ProxyHeader = "X-Forwarded-For"
			appConfig.TrustedProxies = trustedProxies
		case "none":
		default:
			log.Warnf("Proxy '%s' is not supported", viper.GetString("omnibill.webserver.proxy"))
		}
	}

	app := fiber.New(appConfig)
	app.Use(recover.New())
	app.Use(earlydata.New())
	app.Use(healthcheck.New())
	app.Use(helmet.New())
	app.Use(etag.New())
	app.Use(limiter.New(limiter.Config{
		Max:               250,
		Expiration:        3 * time.Second,
		LimiterMiddleware: limiter.SlidingWindow{},
	}))
	app.Use("/assets", filesystem.New(filesystem.Config{
		Root:       http.FS(assetDir),
		PathPrefix: "assets",
		Browse:     false,
	}))

	storage := postgres.New(postgres.Config{
		DB:    dbPool,
		Table: "sessions",
	})
	authSessionStore := session.New(session.Config{
		Storage: storage,
	})
	sessionStore := session.New(session.Config{
		KeyLookup: "cookie:osession",
	})

	for _, handler := range utils.Handlers {
		handlerType := reflect.TypeOf(handler).Elem()
		handlerValue := reflect.ValueOf(handler).Elem()

		pathField, ok := handlerType.FieldByName("Path")
		if !ok {
			fmt.Println("invalid handler")
			continue
		}

		var requireAuth bool

		omnibillTag := pathField.Tag.Get("omnibill")
		for _, option := range strings.Split(omnibillTag, ",") {
			switch option {
			case "requireAuth":
				requireAuth = true
			}
		}

		var pathHandlers []fiber.Handler
		if requireAuth {
			pathHandlers = append(pathHandlers, nil)
		}

		handlerValue.FieldByName("Db").Set(reflect.ValueOf(db))
		handlerValue.FieldByName("AuthSessionStore").Set(reflect.ValueOf(authSessionStore))
		handlerValue.FieldByName("SessionStore").Set(reflect.ValueOf(sessionStore))
		handlerValue.FieldByName("Logger").Set(reflect.ValueOf(logger))
		handlerValue.FieldByName("WebAuthn").Set(reflect.ValueOf(webAuthn))

		path := handlerValue.FieldByName("Path").String()
		if path == "index" {
			path = ""
		}
		path = "/" + path

		if iHandler, ok := handler.(utils.GET); ok {
			pathHandlers = append(pathHandlers, iHandler.Get)
			app.Get(path, func(ctx *fiber.Ctx) error {
				sess, err := sessionStore.Get(ctx)
				if err != nil {
					return fiber.ErrInternalServerError
				}

				handlerValue.FieldByName("Session").Set(reflect.ValueOf(sess))
				for _, pathHandler := range pathHandlers {
					err := pathHandler(ctx)
					if err != nil {
						var e *fiber.Error
						if errors.As(err, &e) {
							return utils.Render(ctx, layouts.Error(*e), templ.WithStatus(e.Code))
						} else {
							return err
						}
					}
				}
				return nil
			})
		}
		if iHandler, ok := handler.(utils.POST); ok {
			pathHandlers = append(pathHandlers, iHandler.Post)
			app.Post(path, func(ctx *fiber.Ctx) error {
				return genericPathHandler(ctx, handlerValue, sessionStore, pathHandlers)
			})
		}
		if iHandler, ok := handler.(utils.PUT); ok {
			pathHandlers = append(pathHandlers, iHandler.Put)
			app.Put(path, func(ctx *fiber.Ctx) error {
				return genericPathHandler(ctx, handlerValue, sessionStore, pathHandlers)
			})
		}
		if iHandler, ok := handler.(utils.DELETE); ok {
			pathHandlers = append(pathHandlers, iHandler.Delete)
			app.Delete(path, func(ctx *fiber.Ctx) error {
				return genericPathHandler(ctx, handlerValue, sessionStore, pathHandlers)
			})
		}
		if iHandler, ok := handler.(utils.PATCH); ok {
			pathHandlers = append(pathHandlers, iHandler.Patch)
			app.Patch(path, func(ctx *fiber.Ctx) error {
				return genericPathHandler(ctx, handlerValue, sessionStore, pathHandlers)
			})
		}
		if iHandler, ok := handler.(utils.OPTIONS); ok {
			pathHandlers = append(pathHandlers, iHandler.Options)
			app.Options(path, func(ctx *fiber.Ctx) error {
				return genericPathHandler(ctx, handlerValue, sessionStore, pathHandlers)
			})
		}
		if iHandler, ok := handler.(utils.HEAD); ok {
			pathHandlers = append(pathHandlers, iHandler.Head)
			app.Head(path, func(ctx *fiber.Ctx) error {
				return genericPathHandler(ctx, handlerValue, sessionStore, pathHandlers)
			})
		}
	}

}

func genericPathHandler(ctx *fiber.Ctx, handler reflect.Value, sessionStore *session.Store, handlers []fiber.Handler) error {
	sess, err := sessionStore.Get(ctx)
	if err != nil {
		return fiber.ErrInternalServerError
	}

	handler.FieldByName("Session").Set(reflect.ValueOf(sess))
	for _, pathHandler := range handlers {
		err := pathHandler(ctx)
		if err != nil {
			var e *fiber.Error
			if errors.As(err, &e) {
				return err
			} else {
				return fiber.ErrInternalServerError
			}
		}
	}
	return nil
}