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koreader/plugins/calibre.koplugin/metadata.lua
2024-06-09 19:28:21 +02:00

285 lines
8.4 KiB
Lua

--[[--
This module implements functions for loading, saving and editing calibre metadata files.
Calibre uses JSON to store metadata on device after each wired transfer.
In wireless transfers calibre sends the same metadata to the client, which is in charge
of storing it.
@module koplugin.calibre.metadata
--]]--
local lfs = require("libs/libkoreader-lfs")
local rapidjson = require("rapidjson")
local logger = require("logger")
local parser = require("parser")
local util = require("util")
local time = require("ui/time")
local used_metadata = {
"uuid",
"lpath",
"last_modified",
"size",
"title",
"authors",
"tags",
"series",
"series_index"
}
-- The search metadata cache requires an even smaller subset
local search_used_metadata = {
"lpath",
"size",
"title",
"authors",
"tags",
"series",
"series_index"
}
local function slim(book, is_search)
local slim_book = rapidjson.object({})
for _, k in ipairs(is_search and search_used_metadata or used_metadata) do
if k == "series" or k == "series_index" then
slim_book[k] = book[k] or rapidjson.null
elseif k == "tags" or k == "authors" then
slim_book[k] = book[k] or rapidjson.array({})
else
slim_book[k] = book[k]
end
end
return slim_book
end
-- This is the max file size we attempt to decode using rapidjson.
-- For larger files we use a sax parser to avoid OOM errors
local MAX_JSON_FILESIZE = 50 * 1024 * 1024
--- find calibre files for a given dir
local function findCalibreFiles(dir)
local function existOrLast(file)
local fullname
local options = { file, "." .. file }
for _, option in ipairs(options) do
fullname = dir .. "/" .. option
if util.fileExists(fullname) then
return true, fullname
end
end
return false, fullname
end
local ok_meta, file_meta = existOrLast("metadata.calibre")
local ok_drive, file_drive = existOrLast("driveinfo.calibre")
return ok_meta, ok_drive, file_meta, file_drive
end
local CalibreMetadata = {
-- info about the library itself. It should
-- hold a table with the contents of "driveinfo.calibre"
drive = rapidjson.array({}),
-- info about the books in this library. It should
-- hold a table with the contents of "metadata.calibre"
books = rapidjson.array({}),
}
--- loads driveinfo from JSON file
function CalibreMetadata:loadDeviceInfo(file)
if not file then file = self.driveinfo end
local json, err = rapidjson.load(file)
if not json then
logger.warn("Unable to load device info from JSON file:", err)
return {}
end
return json
end
-- saves driveinfo to JSON file
function CalibreMetadata:saveDeviceInfo(arg)
-- keep previous device name. This allow us to identify the calibre driver used.
-- "Folder" is used by connect to folder
-- "KOReader" is used by smart device app
-- "Amazon", "Kobo", "Bq" ... are used by platform device drivers
local previous_name = self.drive.device_name
self.drive = arg
if previous_name then
self.drive.device_name = previous_name
end
rapidjson.dump(self.drive, self.driveinfo)
end
-- loads books' metadata from JSON file
function CalibreMetadata:loadBookList()
local attr = lfs.attributes(self.metadata)
if not attr then
logger.warn("Unable to get file attributes from JSON file:", self.metadata)
return rapidjson.array({})
end
local valid = attr.mode == "file" and attr.size > 0
if not valid then
logger.warn("File is invalid", self.metadata)
return rapidjson.array({})
end
local books, err
local impl = G_reader_settings:readSetting("calibre_json_parser") or attr.size > MAX_JSON_FILESIZE and "safe" or "fast"
if impl == "fast" then
books, err = rapidjson.load_calibre(self.metadata)
elseif impl == "safe" then
books, err = parser.parseFile(self.metadata)
else
books, err = rapidjson.load(self.metadata)
end
if not books then
logger.warn(string.format("Unable to load library from json file %s: \n%s",
self.metadata, err))
return rapidjson.array({})
end
return books
end
-- saves books' metadata to JSON file
function CalibreMetadata:saveBookList()
local file = self.metadata
local books = self.books
rapidjson.dump(books, file, { pretty = true })
end
-- add a book to our books table
function CalibreMetadata:addBook(book)
-- prevent duplicate entries
local _, index = self:getBookUuid(book.lpath)
if index then
self.books[index] = slim(book)
else
table.insert(self.books, #self.books + 1, slim(book))
end
end
-- remove a book from our books table
function CalibreMetadata:removeBook(lpath)
local function drop_lpath(t, i, j)
return t[i].lpath ~= lpath
end
util.arrayRemove(self.books, drop_lpath)
end
-- gets the uuid and index of a book from its path
function CalibreMetadata:getBookUuid(lpath)
for index, book in ipairs(self.books) do
if book.lpath == lpath then
return book.uuid, index
end
end
return "none"
end
-- gets the book id at the given index
function CalibreMetadata:getBookId(index)
local book = {}
book.priKey = index
for _, key in ipairs({"uuid", "lpath", "last_modified"}) do
book[key] = self.books[index][key]
end
return book
end
-- gets the book metadata at the given index
function CalibreMetadata:getBookMetadata(index)
return self.books[index]
end
-- removes deleted books from table
function CalibreMetadata:prune()
local count = 0
for index, book in ipairs(self.books) do
local path = self.path .. "/" .. book.lpath
if not util.fileExists(path) then
logger.dbg("prunning book from DB at index", index, "path", path)
self:removeBook(book.lpath)
count = count + 1
end
end
if count > 0 then
self:saveBookList()
end
return count
end
-- removes unused metadata from books
function CalibreMetadata:cleanUnused(is_search)
for index, book in ipairs(self.books) do
self.books[index] = slim(book, is_search)
end
-- We don't want to stomp on the library's actual JSON db for metadata searches.
if is_search then
return
end
self:saveBookList()
end
-- cleans all temp data stored for current library.
function CalibreMetadata:clean()
self.books = rapidjson.array({})
self.drive = rapidjson.array({})
self.path = nil
self.driveinfo = nil
self.metadata = nil
end
-- get keys from driveinfo.calibre
function CalibreMetadata:getDeviceInfo(dir, kind)
if not dir or not kind then return end
local _, ok_drive, __, driveinfo = findCalibreFiles(dir)
if not ok_drive then return end
local drive = self:loadDeviceInfo(driveinfo)
if drive then
return drive[kind]
end
end
-- initialize a directory as a calibre library.
-- This is the main function. Call it to initialize a calibre library
-- in a given path. It will find calibre files if they're on disk and
-- try to load info from them.
-- NOTE: Take special notice of the books table, because it could be huge.
-- If you're not working with the metadata directly (ie: in wireless connections)
-- you should copy relevant data to another table and free this one to keep things tidy.
function CalibreMetadata:init(dir, is_search)
if not dir then return end
local start_time = time.now()
self.path = dir
local ok_meta, ok_drive, file_meta, file_drive = findCalibreFiles(dir)
self.driveinfo = file_drive
if ok_drive then
self.drive = self:loadDeviceInfo()
end
self.metadata = file_meta
if ok_meta then
self.books = self:loadBookList()
elseif is_search then
-- no metadata to search
return false
end
local msg
if is_search then
self:cleanUnused(is_search)
msg = string.format("(search) in %.3f milliseconds: %d books",
time.to_ms(time.since(start_time)), #self.books)
else
local deleted_count = self:prune()
self:cleanUnused()
msg = string.format("in %.3f milliseconds: %d books. %d pruned",
time.to_ms(time.since(start_time)), #self.books, deleted_count)
end
logger.info(string.format("calibre info loaded from disk %s", msg))
return true
end
return CalibreMetadata