package handler

import (
	"context"
	"html/template"
	"net/url"
	"sort"
	"strconv"
	"strings"
	"time"

	"git.frostfs.info/TrueCloudLab/frostfs-http-gw/internal/data"
	"git.frostfs.info/TrueCloudLab/frostfs-http-gw/utils"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
	"github.com/docker/go-units"
	"github.com/valyala/fasthttp"
	"go.uber.org/zap"
)

const (
	dateFormat   = "02-01-2006 15:04"
	attrOID      = "OID"
	attrCreated  = "Created"
	attrFileName = "FileName"
	attrSize     = "Size"
)

type (
	BrowsePageData struct {
		BucketInfo *data.BucketInfo
		Prefix     string
		Objects    []ResponseObject
	}
	ResponseObject struct {
		OID      string
		Created  string
		FileName string
		FilePath string
		Size     string
		IsDir    bool
	}
)

func newListObjectsResponseS3(attrs map[string]string) ResponseObject {
	return ResponseObject{
		OID:      attrs[attrOID],
		Created:  attrs[attrCreated],
		FileName: attrs[attrFileName],
		Size:     attrs[attrSize],
		IsDir:    attrs[attrOID] == "",
	}
}

func newListObjectsResponseNative(attrs map[string]string) ResponseObject {
	return ResponseObject{
		OID:      attrs[attrOID],
		Created:  attrs[object.AttributeTimestamp] + "000",
		FileName: lastPathElement(attrs[object.AttributeFilePath]),
		FilePath: attrs[object.AttributeFilePath],
		Size:     attrs[attrSize],
		IsDir:    false,
	}
}

func getNextDir(filepath, prefix string) string {
	restPath := strings.Replace(filepath, prefix, "", 1)
	index := strings.Index(restPath, "/")
	if index == -1 {
		return ""
	}
	return restPath[:index]
}

func lastPathElement(path string) string {
	index := strings.LastIndex(path, "/")
	if index == len(path)-1 {
		index = strings.LastIndex(path[:index], "/")
	}
	return path[index+1:]
}

func parseTimestamp(tstamp string) (time.Time, error) {
	millis, err := strconv.ParseInt(tstamp, 10, 64)
	if err != nil {
		return time.Time{}, err
	}

	return time.UnixMilli(millis), nil
}

func formatTimestamp(strdate string) string {
	date, err := parseTimestamp(strdate)
	if err != nil || date.IsZero() {
		return ""
	}

	return date.Format(dateFormat)
}

func formatSize(strsize string) string {
	size, err := strconv.ParseFloat(strsize, 64)
	if err != nil {
		return "0B"
	}
	return units.HumanSize(size)
}

func parentDir(prefix string) string {
	index := strings.LastIndex(prefix, "/")
	if index == -1 {
		return prefix
	}
	return prefix[index:]
}

func trimPrefix(encPrefix string) string {
	prefix, err := url.PathUnescape(encPrefix)
	if err != nil {
		return ""
	}
	slashIndex := strings.LastIndex(prefix, "/")
	if slashIndex == -1 {
		return ""
	}
	return prefix[:slashIndex]
}

func urlencode(path string) string {
	var res strings.Builder

	prefixParts := strings.Split(path, "/")
	for _, prefixPart := range prefixParts {
		prefixPart = "/" + url.PathEscape(prefixPart)
		if prefixPart == "/." || prefixPart == "/.." {
			prefixPart = url.PathEscape(prefixPart)
		}
		res.WriteString(prefixPart)
	}

	return res.String()
}

type browseParams struct {
	bucketInfo  *data.BucketInfo
	template    string
	listObjects func(ctx context.Context, bucketName *data.BucketInfo, prefix string) ([]ResponseObject, error)
	prefix      string
}

func (h *Handler) browseObjects(c *fasthttp.RequestCtx, p browseParams) {
	log := h.log.With(
		zap.String("bucket", p.bucketInfo.Name),
		zap.String("container", p.bucketInfo.CID.EncodeToString()),
		zap.String("prefix", p.prefix),
	)
	ctx := utils.GetContextFromRequest(c)
	objects, err := p.listObjects(ctx, p.bucketInfo, p.prefix)
	if err != nil {
		logAndSendBucketError(c, log, err)
		return
	}

	sort.Slice(objects, func(i, j int) bool {
		if objects[i].IsDir == objects[j].IsDir {
			return objects[i].FileName < objects[j].FileName
		}
		return objects[i].IsDir
	})

	tmpl, err := template.New("index").Funcs(template.FuncMap{
		"formatTimestamp": formatTimestamp,
		"formatSize":      formatSize,
		"trimPrefix":      trimPrefix,
		"urlencode":       urlencode,
		"parentDir":       parentDir,
	}).Parse(p.template)
	if err != nil {
		logAndSendBucketError(c, log, err)
		return
	}
	if err = tmpl.Execute(c, &BrowsePageData{
		BucketInfo: p.bucketInfo,
		Prefix:     p.prefix,
		Objects:    objects,
	}); err != nil {
		logAndSendBucketError(c, log, err)
		return
	}
}