package handler

import (
	"cmp"
	_ "embed"
	"html/template"
	"net/url"
	"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"
	"golang.org/x/exp/slices"
)

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

type (
	BrowsePageData struct {
		BucketName,
		Prefix string
		Objects []ResponseObject
	}
	ResponseObject struct {
		OID      string
		Created  string
		FileName string
		Size     string
	}
)

//go:embed templates/index.gotmpl
var defaultTemplate string

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],
	}
}

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 ""
	}
	return units.HumanSize(size)
}

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

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

func urlencode(prefix, filename, size, created string) string {
	res := prefix

	if prefix != "" {
		res += "/"
	}
	res += filename

	if size == "" && created == "" {
		res += "/"
	}

	return url.PathEscape(res)
}

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

	slices.SortFunc(respObjects, func(a, b ResponseObject) int {
		aIsDir := a.Size == ""
		bIsDir := b.Size == ""

		// return root object first
		if a.FileName == "" {
			return -1
		} else if b.FileName == "" {
			return 1
		}

		// dirs objects go first
		if aIsDir && !bIsDir {
			return -1
		} else if !aIsDir && bIsDir {
			return 1
		}
		return cmp.Compare(a.FileName, b.FileName)
	})

	indexTemplate := h.config.IndexPageTemplate()
	if indexTemplate == "" {
		indexTemplate = defaultTemplate
	}
	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
	}
}