package server

import (
	"encoding/json"
	"fmt"
	"net/http"
	"strconv"
	"strings"

	"github.com/NYTimes/gziphandler"
	"github.com/bouk/httprouter"
	"github.com/influxdata/chronograf" // When julienschmidt/httprouter v2 w/ context is out, switch
	"github.com/influxdata/chronograf/oauth2"
)

const (
	// JSONType the mimetype for a json request
	JSONType = "application/json"
)

// MuxOpts are the options for the router.  Mostly related to auth.
type MuxOpts struct {
	Logger      chronograf.Logger
	Develop     bool   // Develop loads assets from filesystem instead of bindata
	Basepath    string // URL path prefix under which all chronograf routes will be mounted
	UseAuth     bool   // UseAuth turns on Github OAuth and JWT
	TokenSecret string

	ProviderFuncs []func(func(oauth2.Provider, oauth2.Mux))
}

// NewMux attaches all the route handlers; handler returned servers chronograf.
func NewMux(opts MuxOpts, service Service) http.Handler {
	router := httprouter.New()

	/* React Application */
	assets := Assets(AssetsOpts{
		Develop: opts.Develop,
		Logger:  opts.Logger,
	})

	// Prefix any URLs found in the React assets with any configured basepath
	prefixedAssets := NewDefaultURLPrefixer(basepath, assets, opts.Logger)

	// Compress the assets with gzip if an accepted encoding
	compressed := gziphandler.GzipHandler(prefixedAssets)

	// The react application handles all the routing if the server does not
	// know about the route.  This means that we never have unknown
	// routes on the server.
	router.NotFound = compressed

	/* Documentation */
	router.GET("/swagger.json", Spec())
	router.GET("/docs", Redoc("/swagger.json"))

	/* API */
	// Sources
	router.GET("/chronograf/v1/sources", service.Sources)
	router.POST("/chronograf/v1/sources", service.NewSource)

	router.GET("/chronograf/v1/sources/:id", service.SourcesID)
	router.PATCH("/chronograf/v1/sources/:id", service.UpdateSource)
	router.DELETE("/chronograf/v1/sources/:id", service.RemoveSource)

	// Source Proxy to Influx
	router.POST("/chronograf/v1/sources/:id/proxy", service.Influx)

	// All possible permissions for users in this source
	router.GET("/chronograf/v1/sources/:id/permissions", service.Permissions)

	// Users associated with the data source
	router.GET("/chronograf/v1/sources/:id/users", service.SourceUsers)
	router.POST("/chronograf/v1/sources/:id/users", service.NewSourceUser)

	router.GET("/chronograf/v1/sources/:id/users/:uid", service.SourceUserID)
	router.DELETE("/chronograf/v1/sources/:id/users/:uid", service.RemoveSourceUser)
	router.PATCH("/chronograf/v1/sources/:id/users/:uid", service.UpdateSourceUser)

	// Roles associated with the data source
	router.GET("/chronograf/v1/sources/:id/roles", service.Roles)
	router.POST("/chronograf/v1/sources/:id/roles", service.NewRole)

	router.GET("/chronograf/v1/sources/:id/roles/:rid", service.RoleID)
	router.DELETE("/chronograf/v1/sources/:id/roles/:rid", service.RemoveRole)
	router.PATCH("/chronograf/v1/sources/:id/roles/:rid", service.UpdateRole)

	// Kapacitor
	router.GET("/chronograf/v1/sources/:id/kapacitors", service.Kapacitors)
	router.POST("/chronograf/v1/sources/:id/kapacitors", service.NewKapacitor)

	router.GET("/chronograf/v1/sources/:id/kapacitors/:kid", service.KapacitorsID)
	router.PATCH("/chronograf/v1/sources/:id/kapacitors/:kid", service.UpdateKapacitor)
	router.DELETE("/chronograf/v1/sources/:id/kapacitors/:kid", service.RemoveKapacitor)

	// Kapacitor rules
	router.GET("/chronograf/v1/sources/:id/kapacitors/:kid/rules", service.KapacitorRulesGet)
	router.POST("/chronograf/v1/sources/:id/kapacitors/:kid/rules", service.KapacitorRulesPost)

	router.GET("/chronograf/v1/sources/:id/kapacitors/:kid/rules/:tid", service.KapacitorRulesID)
	router.PUT("/chronograf/v1/sources/:id/kapacitors/:kid/rules/:tid", service.KapacitorRulesPut)
	router.PATCH("/chronograf/v1/sources/:id/kapacitors/:kid/rules/:tid", service.KapacitorRulesStatus)
	router.DELETE("/chronograf/v1/sources/:id/kapacitors/:kid/rules/:tid", service.KapacitorRulesDelete)

	// Kapacitor Proxy
	router.GET("/chronograf/v1/sources/:id/kapacitors/:kid/proxy", service.KapacitorProxyGet)
	router.POST("/chronograf/v1/sources/:id/kapacitors/:kid/proxy", service.KapacitorProxyPost)
	router.PATCH("/chronograf/v1/sources/:id/kapacitors/:kid/proxy", service.KapacitorProxyPatch)
	router.DELETE("/chronograf/v1/sources/:id/kapacitors/:kid/proxy", service.KapacitorProxyDelete)

	// Mappings
	router.GET("/chronograf/v1/mappings", service.GetMappings)

	// Layouts
	router.GET("/chronograf/v1/layouts", service.Layouts)
	router.POST("/chronograf/v1/layouts", service.NewLayout)

	router.GET("/chronograf/v1/layouts/:id", service.LayoutsID)
	router.PUT("/chronograf/v1/layouts/:id", service.UpdateLayout)
	router.DELETE("/chronograf/v1/layouts/:id", service.RemoveLayout)

	// Users
	router.GET("/chronograf/v1/me", service.Me)

	// Dashboards
	router.GET("/chronograf/v1/dashboards", service.Dashboards)
	router.POST("/chronograf/v1/dashboards", service.NewDashboard)

	router.GET("/chronograf/v1/dashboards/:id", service.DashboardID)
	router.DELETE("/chronograf/v1/dashboards/:id", service.RemoveDashboard)
	router.PUT("/chronograf/v1/dashboards/:id", service.ReplaceDashboard)
	router.PATCH("/chronograf/v1/dashboards/:id", service.UpdateDashboard)

	// Databases
	router.GET("/chronograf/v1/sources/:id/dbs", service.Databases)
	// router.POST("/chronograf/v1/sources/:id/dbs", service.NewDatabase)
	//
	// router.DELETE("/chronograf/v1/sources/:id/dbs/:did", service.DropDatabase)
	//
	// // Retention Policies
	// router.GET("/chronograf/v1/sources/:id/dbs/:did/rps", service.RetentionPolicies)
	// router.POST("/chronograf/v1/sources/:id/dbs/:did/rps", service.NewRetentionPolicy)
	//
	// router.PATCH("/chronograf/v1/sources/:id/dbs/:did/rps/:rpid", service.UpdateRetentionPolicy)
	// router.DELETE("/chronograf/v1/sources/:id/dbs/:did/rps/:rpid", service.DropRetentionPolicy)

	var authRoutes AuthRoutes

	var out http.Handler
	/* Authentication */
	if opts.UseAuth {
		// Encapsulate the router with OAuth2
		var auth http.Handler
		auth, authRoutes = AuthAPI(opts, router)

		// Create middleware to redirect to the appropriate provider logout
		targetURL := "/"
		router.GET("/oauth/logout", Logout(targetURL, authRoutes))

		out = Logger(opts.Logger, auth)
	} else {
		out = Logger(opts.Logger, router)
	}

	router.GET("/chronograf/v1/", AllRoutes(authRoutes, opts.Logger))
	router.GET("/chronograf/v1", AllRoutes(authRoutes, opts.Logger))

	return out
}

// AuthAPI adds the OAuth routes if auth is enabled.
// TODO: this function is not great.  Would be good if providers added their routes.
func AuthAPI(opts MuxOpts, router *httprouter.Router) (http.Handler, AuthRoutes) {
	auth := oauth2.NewJWT(opts.TokenSecret)
	routes := AuthRoutes{}
	for _, pf := range opts.ProviderFuncs {
		pf(func(p oauth2.Provider, m oauth2.Mux) {
			loginPath := fmt.Sprintf("%s/oauth/%s/login", opts.Basepath, strings.ToLower(p.Name()))
			logoutPath := fmt.Sprintf("%s/oauth/%s/logout", opts.Basepath, strings.ToLower(p.Name()))
			callbackPath := fmt.Sprintf("%s/oauth/%s/callback", opts.Basepath, strings.ToLower(p.Name()))
			router.Handler("GET", loginPath, m.Login())
			router.Handler("GET", logoutPath, m.Logout())
			router.Handler("GET", callbackPath, m.Callback())
			routes = append(routes, AuthRoute{
				Name:     p.Name(),
				Label:    strings.Title(p.Name()),
				Login:    loginPath,
				Logout:   logoutPath,
				Callback: callbackPath,
			})
		})
	}

	tokenMiddleware := oauth2.AuthorizedToken(&auth, &oauth2.CookieExtractor{Name: "session"}, opts.Logger, router)
	// Wrap the API with token validation middleware.
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if strings.HasPrefix(r.URL.Path, "/chronograf/v1/") || r.URL.Path == "/oauth/logout" {
			tokenMiddleware.ServeHTTP(w, r)
			return
		}
		router.ServeHTTP(w, r)
	}), routes
}

func encodeJSON(w http.ResponseWriter, status int, v interface{}, logger chronograf.Logger) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	if err := json.NewEncoder(w).Encode(v); err != nil {
		unknownErrorWithMessage(w, err, logger)
	}
}

// Error writes an JSON message
func Error(w http.ResponseWriter, code int, msg string, logger chronograf.Logger) {
	e := ErrorMessage{
		Code:    code,
		Message: msg,
	}
	b, err := json.Marshal(e)
	if err != nil {
		code = http.StatusInternalServerError
		b = []byte(`{"code": 500, "message":"server_error"}`)
	}

	logger.
		WithField("component", "server").
		WithField("http_status ", code).
		Error("Error message ", msg)
	w.Header().Set("Content-Type", JSONType)
	w.WriteHeader(code)
	_, _ = w.Write(b)
}

func invalidData(w http.ResponseWriter, err error, logger chronograf.Logger) {
	Error(w, http.StatusUnprocessableEntity, fmt.Sprintf("%v", err), logger)
}

func invalidJSON(w http.ResponseWriter, logger chronograf.Logger) {
	Error(w, http.StatusBadRequest, "Unparsable JSON", logger)
}

func unknownErrorWithMessage(w http.ResponseWriter, err error, logger chronograf.Logger) {
	Error(w, http.StatusInternalServerError, fmt.Sprintf("Unknown error: %v", err), logger)
}

func notFound(w http.ResponseWriter, id int, logger chronograf.Logger) {
	Error(w, http.StatusNotFound, fmt.Sprintf("ID %d not found", id), logger)
}

func paramID(key string, r *http.Request) (int, error) {
	ctx := r.Context()
	param := httprouter.GetParamFromContext(ctx, key)
	id, err := strconv.Atoi(param)
	if err != nil {
		return -1, fmt.Errorf("Error converting ID %s", param)
	}
	return id, nil
}