package kook

// This file carries the KOOK protocol types and the conversion between a native
// s=0 event payload and the normalized adapter.UnifiedMessage model. KOOK events
// are delivered over the gateway WebSocket: channel_type distinguishes group
// (GROUP/BROADCAST) from private (PERSON), type declares the content kind
// (1 text / 2 image / 3 video / 4 file / 8 audio / 9 kmarkdown / 10 card /
// 255 system), author_id==1 marks a system sender, and extra.author carries the
// sender's user object (id/username/nickname).

import (
	"encoding/json"
	"time"

	"git.yeij.top/AskaEth/Cyrene_v2/internal/channel/adapter"
)

const platformName = "kook"

// KOOK message content kinds (the "type" field of an s=0 event).
const (
	kindText     = 1
	kindImage    = 2
	kindVideo    = 3
	kindFile     = 4
	kindAudio    = 8
	kindKMarkdown = 9
	kindCard     = 10
	kindSystem   = 255
)

// KOOK channel types (the "channel_type" field of an s=0 event).
const (
	channelGroup     = "GROUP"
	channelBroadcast = "BROADCAST"
)

// kookEvent is the "d" payload of an s=0 message event.
type kookEvent struct {
	ChannelType  string          `json:"channel_type"`
	Type         int             `json:"type"`
	TargetID     string          `json:"target_id"`
	AuthorID     string          `json:"author_id"`
	Content      json.RawMessage `json:"content"`
	MsgID        string          `json:"msg_id"`
	MsgTimestamp int64           `json:"msg_timestamp"`
	Nonce        string          `json:"nonce"`
	Extra        json.RawMessage `json:"extra"`
}

// kookExtra carries the per-event auxiliary data (author, guild/channel names,
// mentions). KOOK's field set varies by message type, so all fields are optional.
type kookExtra struct {
	Type        int        `json:"type"`
	GuildID     string     `json:"guild_id"`
	ChannelName string     `json:"channel_name"`
	Mention     []string   `json:"mention"`
	Author      *kookUser  `json:"author"`
}

// kookUser is the sender's user object carried by extra.author.
type kookUser struct {
	ID       string `json:"id"`
	Username string `json:"username"`
	Nickname string `json:"nickname"`
}

// toUnifiedMessage converts a parsed s=0 event payload into a normalized
// UnifiedMessage. It returns ok=false for events that carry no deliverable chat
// message (system messages, non-chat notifications).
func (a *Adapter) toUnifiedMessage(data json.RawMessage, frame []byte) (adapter.UnifiedMessage, bool) {
	var ev kookEvent
	if err := json.Unmarshal(data, &ev); err != nil {
		return adapter.UnifiedMessage{}, false
	}
	if ev.Type == kindSystem || ev.AuthorID == "1" {
		return adapter.UnifiedMessage{}, false
	}

	content := asString(ev.Content)
	var ex kookExtra
	_ = json.Unmarshal(ev.Extra, &ex)

	senderID, senderName := senderOf(&ev, &ex)
	ct, media := messageKind(ev.Type, content)
	group := channelIsGroup(ev.ChannelType)

	msg := adapter.UnifiedMessage{
		Platform:    platformName,
		ChannelType: group,
		ChannelID:   ev.TargetID,
		SenderID:    senderID,
		SenderName:  senderName,
		Content:     content,
		ContentType: ct,
		Media:       media,
		Mentions:    mentionsFrom(ex.Mention),
		MessageID:   ev.MsgID,
		Timestamp:   time.UnixMilli(ev.MsgTimestamp),
		RawData:     frame,
		Sender: adapter.Actor{
			Role:        adapter.RoleUnknown,
			UserID:      senderID,
			DisplayName: senderName,
			GroupID:     "",
			GroupName:   ex.ChannelName,
			IsGroup:     bool(group == adapter.ChannelGroup),
		},
	}

	if group == adapter.ChannelGroup {
		gid := ex.GuildID
		if gid == "" {
			gid = ev.TargetID
		}
		msg.GroupID = gid
		msg.GroupName = ex.ChannelName
		msg.Sender.GroupID = gid
		msg.Sender.GroupName = ex.ChannelName
		a.rememberChannel(msg)
	}

	// Adjust ChannelID: for private messages target_id is the peer user id, which
	// is already set above; for group messages target_id is the channel id.
	return msg, true
}

// senderOf resolves the sender id and display name from the event fields,
// preferring the extra.author nickname (design/16 §4.6: third parties must be
// shown by nickname) with fallbacks to username and the author_id.
func senderOf(ev *kookEvent, ex *kookExtra) (id, name string) {
	id = ev.AuthorID
	name = ev.AuthorID
	if ex.Author == nil {
		return id, name
	}
	if ex.Author.ID != "" {
		id = ex.Author.ID
	}
	switch {
	case ex.Author.Nickname != "":
		name = ex.Author.Nickname
	case ex.Author.Username != "":
		name = ex.Author.Username
	default:
		name = id
	}
	return id, name
}

// channelIsGroup maps a KOOK channel_type onto the adapter's ChannelType.
func channelIsGroup(t string) adapter.ChannelType {
	if t == channelGroup || t == channelBroadcast {
		return adapter.ChannelGroup
	}
	return adapter.ChannelDirect
}

// messageKind maps a KOOK content-kind onto the adapter ContentType and the
// media list (media URL is carried by the content field for image/video/file/
// audio messages).
func messageKind(kind int, content string) (adapter.ContentType, []adapter.Media) {
	switch kind {
	case kindImage:
		return adapter.ContentImage, []adapter.Media{{Kind: adapter.MediaImage, URL: content}}
	case kindVideo:
		return adapter.ContentFile, []adapter.Media{{Kind: adapter.MediaVideo, URL: content}}
	case kindFile:
		return adapter.ContentFile, []adapter.Media{{Kind: adapter.MediaFile, URL: content}}
	case kindAudio:
		return adapter.ContentVoice, []adapter.Media{{Kind: adapter.MediaVoice, URL: content}}
	default:
		return adapter.ContentText, nil
	}
}

// mentionsFrom converts an array of mentioned user ids into adapter.Mention.
func mentionsFrom(ids []string) []adapter.Mention {
	if len(ids) == 0 {
		return nil
	}
	out := make([]adapter.Mention, 0, len(ids))
	for _, id := range ids {
		if id != "" {
			out = append(out, adapter.Mention{UserID: id})
		}
	}
	return out
}

// asString decodes a raw JSON value that is expected to be a string, returning
// "" when it is not.
func asString(raw json.RawMessage) string {
	if len(raw) == 0 {
		return ""
	}
	var s string
	if err := json.Unmarshal(raw, &s); err != nil {
		return ""
	}
	return s
}