package handler

import (
	"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"
	"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 {
		BucketName,
		Prefix string
		Objects []ResponseObject
	}
	ResponseObject struct {
		OID      string
		Created  string
		FileName string
		Size     string
		IsDir    bool
	}
)

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

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(prefix, filename string) string {
	var res strings.Builder
	path := filename
	if prefix != "" {
		path = strings.Join([]string{prefix, filename}, "/")
	}
	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()
}

func (h *Handler) browseObjects(c *fasthttp.RequestCtx, bucketInfo *data.BucketInfo, prefix string) {
	ctx := utils.GetContextFromRequest(c)
	reqLog := utils.GetReqLogOrDefault(ctx, h.log)
	log := reqLog.With(zap.String("bucket", bucketInfo.Name))

	nodes, err := h.listObjects(ctx, bucketInfo, prefix)
	if err != nil {
		logAndSendBucketError(c, log, err)
		return
	}

	respObjects := make([]ResponseObject, len(nodes))

	for i, node := range nodes {
		respObjects[i] = NewResponseObject(node)
	}

	sort.Slice(respObjects, func(i, j int) bool {
		if respObjects[i].IsDir == respObjects[j].IsDir {
			return respObjects[i].FileName < respObjects[j].FileName
		}
		return respObjects[i].IsDir
	})
	indexTemplate := h.config.IndexPageTemplate()

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