package http

import (
	"context"
	nethttp "net/http"
	"strings"

	idpctx "github.com/influxdata/platform/context"
	"github.com/prometheus/client_golang/prometheus"
)

// PlatformHandler is a collection of all the service handlers.
type PlatformHandler struct {
	BucketHandler        *BucketHandler
	UserHandler          *UserHandler
	OrgHandler           *OrgHandler
	AuthorizationHandler *AuthorizationHandler
	DashboardHandler     *DashboardHandler
	AssetHandler         *AssetHandler
	ChronografHandler    *ChronografHandler
	ViewHandler          *ViewHandler
	SourceHandler        *SourceHandler
	TaskHandler          *TaskHandler
	FluxLangHandler      *FluxLangHandler
	WriteHandler         *WriteHandler
}

func setCORSResponseHeaders(w nethttp.ResponseWriter, r *nethttp.Request) {
	if origin := r.Header.Get("Origin"); origin != "" {
		w.Header().Set("Access-Control-Allow-Origin", origin)
		w.Header().Set("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE")
		w.Header().Set("Access-Control-Allow-Headers", "Accept, Content-Type, Content-Length, Accept-Encoding, Authorization")
	}
}

var platformLinks = map[string]interface{}{
	"sources":    "/v2/sources",
	"dashboards": "/v2/dashboards",
	"flux": map[string]string{
		"self":        "/v2/flux",
		"ast":         "/v2/flux/ast",
		"suggestions": "/v2/flux/suggestions",
	},
	"external": map[string]string{
		"statusFeed": "https://www.influxdata.com/feed/json",
	},
}

func (h *PlatformHandler) serveLinks(w nethttp.ResponseWriter, r *nethttp.Request) {
	ctx := r.Context()
	if err := encodeResponse(ctx, w, nethttp.StatusOK, platformLinks); err != nil {
		EncodeError(ctx, err, w)
		return
	}
}

// ServeHTTP delegates a request to the appropriate subhandler.
func (h *PlatformHandler) ServeHTTP(w nethttp.ResponseWriter, r *nethttp.Request) {
	setCORSResponseHeaders(w, r)
	if r.Method == "OPTIONS" {
		return
	}

	// Server the chronograf assets for any basepath that does not start with addressable parts
	// of the platform API.
	if !strings.HasPrefix(r.URL.Path, "/v1") &&
		!strings.HasPrefix(r.URL.Path, "/v2") &&
		!strings.HasPrefix(r.URL.Path, "/chronograf/") {
		h.AssetHandler.ServeHTTP(w, r)
		return
	}

	// Serve the links base links for the API.
	if r.URL.Path == "/v2/" || r.URL.Path == "/v2" {
		h.serveLinks(w, r)
		return
	}

	if strings.HasPrefix(r.URL.Path, "/v2/flux") {
		h.FluxLangHandler.ServeHTTP(w, r)
		return
	}

	if strings.HasPrefix(r.URL.Path, "/chronograf/") {
		h.ChronografHandler.ServeHTTP(w, r)
		return
	}

	ctx := r.Context()
	var err error
	if ctx, err = extractAuthorization(ctx, r); err != nil {
		// TODO(desa): add back eventually when things have settled. See https://github.com/influxdata/platform/issues/593
		//nethttp.Error(w, err.Error(), nethttp.StatusBadRequest)
	}
	r = r.WithContext(ctx)

	if strings.HasPrefix(r.URL.Path, "/v1/buckets") {
		h.BucketHandler.ServeHTTP(w, r)
		return
	}

	if strings.HasPrefix(r.URL.Path, "/v1/users") {
		h.UserHandler.ServeHTTP(w, r)
		return
	}

	if strings.HasPrefix(r.URL.Path, "/v1/orgs") {
		h.OrgHandler.ServeHTTP(w, r)
		return
	}

	if strings.HasPrefix(r.URL.Path, "/v1/authorizations") {
		h.AuthorizationHandler.ServeHTTP(w, r)
		return
	}

	if strings.HasPrefix(r.URL.Path, "/v2/dashboards") {
		h.DashboardHandler.ServeHTTP(w, r)
		return
	}

	if strings.HasPrefix(r.URL.Path, "/v2/sources") {
		h.SourceHandler.ServeHTTP(w, r)
		return
	}

	if strings.HasPrefix(r.URL.Path, "/v1/tasks") {
		h.TaskHandler.ServeHTTP(w, r)
		return
	}

	if strings.HasSuffix(r.URL.Path, "/write") {
		h.WriteHandler.ServeHTTP(w, r)
		return
	}

	if strings.HasPrefix(r.URL.Path, "/v2/views") {
		h.ViewHandler.ServeHTTP(w, r)
		return
	}

	nethttp.NotFound(w, r)
}

// PrometheusCollectors satisfies the prom.PrometheusCollector interface.
func (h *PlatformHandler) PrometheusCollectors() []prometheus.Collector {
	// TODO: collect and return relevant metrics.
	return nil
}

func extractAuthorization(ctx context.Context, r *nethttp.Request) (context.Context, error) {
	t, err := GetToken(r)
	if err != nil {
		return ctx, err
	}
	return idpctx.SetToken(ctx, t), nil
}