package server

import (
	"fmt"
	"strings"

	"chat-agent-system/internal/chat"
	"chat-agent-system/internal/coordinator"
)

// prepareChatTurn 允许「只上传文档、不写文字」。落库文字由文件名合成，原始空串不会进入模型。
func prepareChatTurn(message string, atts []TurnAttachment) (stored string, attachmentOnly bool, reject string) {
	atts = normalizeTurnAttachments(atts)
	message = strings.TrimSpace(message)
	if message == "" && len(atts) == 0 {
		return "", false, "message cannot be empty"
	}
	if message == "" {
		return attachmentOnlyStoredMessage(atts), true, ""
	}
	return message, false, ""
}

func normalizeTurnAttachments(atts []TurnAttachment) []TurnAttachment {
	if len(atts) == 0 {
		return nil
	}
	out := make([]TurnAttachment, 0, len(atts))
	for _, att := range atts {
		att.Filename = strings.TrimSpace(att.Filename)
		att.DocID = strings.TrimSpace(att.DocID)
		att.ParseState = strings.TrimSpace(att.ParseState)
		if att.Filename == "" && att.DocID == "" && att.AssetID == 0 {
			continue
		}
		if att.Filename == "" {
			att.Filename = "未命名文档"
		}
		out = append(out, att)
	}
	if len(out) == 0 {
		return nil
	}
	return out
}

func attachmentOnlyStoredMessage(atts []TurnAttachment) string {
	names := make([]string, 0, len(atts))
	for _, att := range atts {
		names = append(names, "《"+strings.Trim(att.Filename, "《》")+"》")
	}
	return "已上传文档：" + strings.Join(names, "、")
}

func turnAttachmentHashKey(atts []TurnAttachment) string {
	atts = normalizeTurnAttachments(atts)
	if len(atts) == 0 {
		return ""
	}
	parts := make([]string, 0, len(atts))
	for _, att := range atts {
		parts = append(parts, fmt.Sprintf("%s|%s|%d|%s", att.Filename, att.DocID, att.AssetID, att.ParseState))
	}
	return strings.Join(parts, ";")
}

func (s *Server) bindTurnAttachments(sess *chat.Session, atts []TurnAttachment, attachmentOnly bool) {
	if sess == nil || sess.UserCtx == nil {
		return
	}
	atts = normalizeTurnAttachments(atts)
	refs := make([]coordinator.TurnAttachmentRef, 0, len(atts))
	for _, att := range atts {
		refs = append(refs, coordinator.TurnAttachmentRef{
			Filename:   att.Filename,
			DocID:      att.DocID,
			AssetID:    att.AssetID,
			ParseState: att.ParseState,
		})
	}
	sess.UserCtx.PendingTurnAttachments = refs
	sess.UserCtx.AttachmentOnlyTurn = attachmentOnly && len(refs) > 0
}