package isphere

import (
	"path/filepath"
	"regexp"
	"sort"
	"strings"
)

type File struct {
	FileID         string
	MessageID      string
	ConversationID string
	FileName       string
	SizeBytes      *int64
	MimeType       string
	CreatedAt      string
	DownloadRef    string
	SavedPath      string
	SHA256         string
	Source         string
	RawRef         string
}

type ListFilesQuery struct {
	ConversationID string
	MessageID      string
	FileID         string
	NameContains   string
	Limit          int
}

type ListFilesResult struct {
	Files []File
}

var fileNamePattern = regexp.MustCompile(`(?i)[^\s<>:"|?*]+\.(?:docx?|xlsx?|pptx?|pdf|zip|rar|png|jpe?g|txt|csv)\b`)

func ListFilesFromMessages(messages []Message, query ListFilesQuery) ListFilesResult {
	files := make([]File, 0)
	for _, message := range messages {
		if !messageLooksFileBacked(message) {
			continue
		}
		fileName := extractMessageFileName(message.Text)
		if fileName == "" {
			continue
		}
		file := File{
			FileID:         fileID(message.ID, fileName),
			MessageID:      message.ID,
			ConversationID: message.ConversationID,
			FileName:       fileName,
			MimeType:       mimeTypeForFileName(fileName),
			CreatedAt:      message.Timestamp,
			Source:         "local_readonly",
			RawRef:         "packetlog_file_transfer",
		}
		if fileMatchesQuery(file, query) {
			files = append(files, file)
		}
	}

	sort.Slice(files, func(i, j int) bool {
		if files[i].FileID == files[j].FileID {
			return files[i].MessageID < files[j].MessageID
		}
		return files[i].FileID < files[j].FileID
	})

	limit := query.Limit
	if limit <= 0 || limit > len(files) {
		limit = len(files)
	}
	return ListFilesResult{Files: files[:limit]}
}

func messageLooksFileBacked(message Message) bool {
	return strings.Contains(strings.ToUpper(message.Subject), "FILE_TRANSFER") || extractMessageFileName(message.Text) != ""
}

func extractMessageFileName(text string) string {
	match := fileNamePattern.FindString(strings.TrimSpace(text))
	return strings.Trim(match, " .,;，。；")
}

func fileID(messageID string, fileName string) string {
	if messageID == "" {
		return fileName
	}
	return messageID + ":" + fileName
}

func fileMatchesQuery(file File, query ListFilesQuery) bool {
	if query.ConversationID != "" && file.ConversationID != query.ConversationID {
		return false
	}
	if query.MessageID != "" && file.MessageID != query.MessageID {
		return false
	}
	if query.FileID != "" && file.FileID != query.FileID {
		return false
	}
	nameQuery := strings.ToLower(strings.TrimSpace(query.NameContains))
	if nameQuery != "" && !strings.Contains(strings.ToLower(file.FileName), nameQuery) {
		return false
	}
	return true
}

func mimeTypeForFileName(name string) string {
	switch strings.ToLower(filepath.Ext(name)) {
	case ".doc":
		return "application/msword"
	case ".docx":
		return "application/vnd.openxmlformats-officedocument.wordprocessingml.document"
	case ".xls":
		return "application/vnd.ms-excel"
	case ".xlsx":
		return "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
	case ".ppt":
		return "application/vnd.ms-powerpoint"
	case ".pptx":
		return "application/vnd.openxmlformats-officedocument.presentationml.presentation"
	case ".pdf":
		return "application/pdf"
	case ".zip":
		return "application/zip"
	case ".rar":
		return "application/vnd.rar"
	case ".png":
		return "image/png"
	case ".jpg", ".jpeg":
		return "image/jpeg"
	case ".txt":
		return "text/plain"
	case ".csv":
		return "text/csv"
	default:
		return ""
	}
}