package main

import (
	"encoding/json"
	"hash/fnv"
	"strings"

	"github.com/tinode/chat/server/store"
	"github.com/tinode/chat/server/store/types"
)

const (
	imAssetsConfigGroup             = "im_assets"
	imDefaultMaleAvatarURLsConfig   = "default_user_avatar_male_urls"
	imDefaultFemaleAvatarURLsConfig = "default_user_avatar_female_urls"
)

func applyDefaultUserAvatar(data map[string]any, userID, gender string) {
	if data == nil || strings.TrimSpace(stringFromAny(data["avatar_file_id"])) != "" {
		return
	}
	if avatarURL := defaultUserAvatarURL(userID, gender); avatarURL != "" {
		data["avatar_file_id"] = avatarURL
	}
}

func defaultUserAvatarURL(userID, gender string) string {
	if store.ThirdPartyConfig == nil {
		return ""
	}
	values, err := store.ThirdPartyConfig.Get(imAssetsConfigGroup, imDefaultMaleAvatarURLsConfig, imDefaultFemaleAvatarURLsConfig)
	if err != nil {
		return ""
	}
	key := imDefaultMaleAvatarURLsConfig
	if strings.EqualFold(strings.TrimSpace(gender), "female") {
		key = imDefaultFemaleAvatarURLsConfig
	}
	urls := parseDefaultAvatarURLs(values[key])
	if len(urls) == 0 && key == imDefaultFemaleAvatarURLsConfig {
		urls = parseDefaultAvatarURLs(values[imDefaultMaleAvatarURLsConfig])
	}
	if len(urls) == 0 {
		return ""
	}
	return urls[defaultAvatarIndex(userID, len(urls))]
}

func parseDefaultAvatarURLs(raw string) []string {
	var urls []string
	if err := json.Unmarshal([]byte(strings.TrimSpace(raw)), &urls); err != nil {
		return nil
	}
	out := urls[:0]
	for _, url := range urls {
		if url = strings.TrimSpace(url); url != "" {
			out = append(out, url)
		}
	}
	return out
}

func defaultAvatarIndex(userID string, count int) int {
	if count <= 1 {
		return 0
	}
	uid := types.ParseUserId(strings.TrimSpace(userID))
	if uid.IsZero() {
		uid = types.ParseUid(strings.TrimSpace(userID))
	}
	if !uid.IsZero() {
		return int(uint64(uid) % uint64(count))
	}
	h := fnv.New32a()
	_, _ = h.Write([]byte(userID))
	return int(h.Sum32() % uint32(count))
}