package main

import (
	"io"
	"net/http"
	"path"
	"strconv"
	"strings"
	"sync"
	"time"

	sdk "github.com/nspcc-dev/cdn-neofs-sdk"
	"github.com/nspcc-dev/neofs-api-go/pkg/container"
	"github.com/nspcc-dev/neofs-api-go/pkg/object"
	"github.com/pkg/errors"
	"github.com/valyala/fasthttp"
	"go.uber.org/zap"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
)

type (
	detector struct {
		io.Writer
		sync.Once

		contentType string
	}

	request struct {
		*fasthttp.RequestCtx

		log *zap.Logger
		obj sdk.ObjectClient
	}

	objectIDs []*object.ID
)

func newDetector(w io.Writer) *detector {
	return &detector{Writer: w}
}

func (d *detector) Write(data []byte) (int, error) {
	d.Once.Do(func() {
		d.contentType = http.DetectContentType(data)
	})

	return d.Writer.Write(data)
}

func (r *request) receiveFile(address *object.Address) {
	var (
		err      error
		dis      = "inline"
		start    = time.Now()
		filename string
	)

	writer := newDetector(r.Response.BodyWriter())
	obj, err := r.obj.Get(r, address, sdk.WithGetWriter(writer))
	if err != nil {
		r.log.Error("could not receive object",
			zap.Stringer("elapsed", time.Since(start)),
			zap.Error(err))

		var (
			msg  = errors.Wrap(err, "could not receive object").Error()
			code = fasthttp.StatusBadRequest
		)

		if st, ok := status.FromError(errors.Cause(err)); ok && st != nil {
			if st.Code() == codes.NotFound {
				code = fasthttp.StatusNotFound
			}

			msg = st.Message()
		}

		r.Error(msg, code)
		return
	}

	if r.Request.URI().QueryArgs().GetBool("download") {
		dis = "attachment"
	}

	r.Response.Header.Set("Content-Length", strconv.FormatUint(obj.PayloadSize(), 10))
	r.Response.Header.Set("x-object-id", obj.ID().String())
	r.Response.Header.Set("x-owner-id", obj.OwnerID().String())
	r.Response.Header.Set("x-container-id", obj.ContainerID().String())

	for _, attr := range obj.Attributes() {
		key := attr.Key()
		val := attr.Value()

		r.Response.Header.Set("x-"+key, val)

		switch key {
		case object.AttributeFileName:
			filename = val
		case object.AttributeTimestamp:
			value, err := strconv.ParseInt(val, 10, 64)
			if err != nil {
				r.log.Info("couldn't parse creation date",
					zap.String("key", key),
					zap.String("val", val),
					zap.Error(err))
				continue
			}

			r.Response.Header.Set("Last-Modified",
				time.Unix(value, 0).Format(time.RFC1123))
		}

	}

	r.SetContentType(writer.contentType)
	r.Response.Header.Set("Content-Disposition", dis+"; filename="+path.Base(filename))
}

func (o objectIDs) Slice() []string {
	res := make([]string, 0, len(o))
	for _, oid := range o {
		res = append(res, oid.String())
	}

	return res
}

func (a *app) request(ctx *fasthttp.RequestCtx, log *zap.Logger) *request {
	return &request{
		RequestCtx: ctx,

		log: log,
		obj: a.cli.Object(),
	}
}

func (a *app) byAddress(c *fasthttp.RequestCtx) {
	var (
		err    error
		adr    = object.NewAddress()
		cid, _ = c.UserValue("cid").(string)
		oid, _ = c.UserValue("oid").(string)
		val    = strings.Join([]string{cid, oid}, "/")
		log    = a.log.With(
			zap.String("cid", cid),
			zap.String("oid", oid))
	)

	if err = adr.Parse(val); err != nil {
		log.Error("wrong object address", zap.Error(err))
		c.Error("wrong object address", fasthttp.StatusBadRequest)
		return
	}

	a.request(c, log).receiveFile(adr)
}

func (a *app) byAttribute(c *fasthttp.RequestCtx) {
	var (
		err     error
		ids     []*object.ID
		cid     = container.NewID()
		adr     = object.NewAddress()
		sCID, _ = c.UserValue("cid").(string)
		key, _  = c.UserValue("attr_key").(string)
		val, _  = c.UserValue("attr_val").(string)

		log = a.log.With(
			zap.String("cid", sCID),
			zap.String("attr_key", key),
			zap.String("attr_val", val))
	)

	if err = cid.Parse(sCID); err != nil {
		log.Error("wrong container id", zap.Error(err))
		c.Error("wrong container id", fasthttp.StatusBadRequest)
		return
	} else if ids, err = a.cli.Object().Search(c, cid, sdk.SearchRootObjects(), sdk.SearchByAttribute(key, val)); err != nil {
		log.Error("something went wrong", zap.Error(err))
		c.Error("something went wrong", fasthttp.StatusBadRequest)
		return
	} else if len(ids) == 0 {
		c.Error("not found", fasthttp.StatusNotFound)
		return
	}

	if len(ids) > 1 {
		log.Debug("found multiple objects",
			zap.Strings("object_ids", objectIDs(ids).Slice()),
			zap.Stringer("show_object_id", ids[0]))
	}

	adr.SetContainerID(cid)
	adr.SetObjectID(ids[0])
	a.request(c, log).receiveFile(adr)
}