feat(api): add ISBN lookup functionality to retrieve book ID

    end

end

--[[--

Look up a book in the Booklore library by ISBN.

Uses the metadata isbn-lookup endpoint which matches the ISBN against books

already in the library and returns the matched book's ID.

Endpoint: POST /api/v1/books/metadata/isbn-lookup

Body: { "isbn": "<isbn_string>" }

@param isbn string Raw ISBN digits (10 or 13, no prefix)

@param username string Booklore username

@param password string Booklore password

@return boolean success

@return number|string bookId on success, error message on failure

--]]

function APIClient:lookupBookByIsbn(isbn, username, password)

    self:logInfo("BookloreSync API: Looking up book by ISBN via metadata endpoint:", isbn)

    local login_success, token = self:getOrRefreshBearerToken(username, password)

    if not login_success then

        self:logErr("BookloreSync API: Failed to get Bearer token:", token)

        return false, token or "Authentication failed"

    end

    local headers = {

        ["Authorization"] = "Bearer " .. token

    }

    local body = { isbn = isbn }

    local success, code, response = self:request("POST", "/api/v1/books/metadata/isbn-lookup", body, headers)

    -- If we get 401/403, token might be invalid - retry with fresh token

    if not success and (code == 401 or code == 403) then

        self:logWarn("BookloreSync API: Token rejected (401/403), refreshing and retrying")

        if self.db then

            self.db:deleteBearerToken(username)

        end

        local refresh_success, new_token = self:getOrRefreshBearerToken(username, password, true)

        if refresh_success then

            headers["Authorization"] = "Bearer " .. new_token

            success, code, response = self:request("POST", "/api/v1/books/metadata/isbn-lookup", body, headers)

        else

            return false, new_token or "Authentication failed after refresh"

        end

    end

    if success and type(response) == "table" and response.bookId then

        local book_id = tonumber(response.bookId)

        self:logInfo("BookloreSync API: ISBN lookup found book ID:", book_id)

        return true, book_id

    else

        local error_msg = (type(response) == "string" and response) or "No book found for ISBN"

        self:logWarn("BookloreSync API: ISBN lookup failed:", error_msg)

        return false, error_msg

    end

end

--[[--

URL encode a string