-------------------------------------------------------------------------------
--         FILE:  luaotfload-log.lua
--  DESCRIPTION:  part of luaotfload / logging
-------------------------------------------------------------------------------


assert(luaotfload_module, "This is a part of luaotfload and should not be loaded independently") { 
    name          = "luaotfload-log",
    version       = "3.24",       --TAGVERSION
    date          = "2023-08-19", --TAGDATE
    description   = "luaotfload submodule / logging",
    license       = "GPL v2.0",
    author        = "Khaled Hosny, Elie Roux, Philipp Gesang",
    copyright     = "Luaotfload Development Team",  
}

--[[doc--
The logging system is slow in general, as we always have the function
call overhead even if we aren’t going to output anything. On the other
hand, the more efficient approach followed by Context isn’t an option
because we lack a user interface to toggle per-subsystem tracing.
--doc]]--

local module_name       = "luaotfload" --- prefix for messages
local debug             = debug

luaotfload              = luaotfload or { }
luaotfload.log          = luaotfload.log or { }
local log               = luaotfload.log

local ioopen            = io.open
local iowrite           = io.write
local lfsisdir          = lfs.isdir
local lfsisfile         = lfs.isfile
local osdate            = os.date
local ostime            = os.time
local osuuid            = os.uuid
local select            = select
local stringformat      = string.format
local stringsub         = string.sub
local tableconcat       = table.concat
local texiowrite_nl     = texio.write_nl
local texiowrite        = texio.write
local type              = type

local dummyfunction     = function () end

local texjob = false
if tex and (tex.jobname or tex.formatname) then
    --- TeX
    texjob = true
end

local loglevel = 0 --- default
local logout   = "log"

--- int -> bool
local function set_loglevel (n)
    if type(n) == "number" then
        loglevel = n
    end
    return true
end
log.set_loglevel   = set_loglevel

--- unit -> int
local function get_loglevel ( )
    return loglevel
end
log.get_loglevel   = get_loglevel

local writeln  --- pointer to terminal/log writer
local statusln --- terminal writer that reuses the current line
local first_status = true --- indicate the begin of a status region

local log_msg = [[
logging output redirected to %s
to monitor the progress run "tail -f %s" in another terminal
]]

local tmppath = os.getenv "TMPDIR" or "/tmp"

local function choose_logfile ( )
    if lfsisdir (tmppath) then
        local fname
        repeat --- ensure that file of that name doesn’t exist
            fname = tmppath .. "/luaotfload-log-" .. osuuid()
        until not lfsisfile (fname)
        iowrite (stringformat (log_msg, fname, fname))
        return ioopen (fname, "w")
    end
    --- missing /tmp
    return false
end

local function set_logout (s, finalizers)
    if s == "stdout" then
        logout = "redirect"
    elseif s == "file" then --- inject custom logger
        logout = "redirect"
        local chan = choose_logfile ()
        chan:write (stringformat ("logging initiated at %s",
                                  osdate ("%Y-%m-%d %H:%M:%S", --- i. e. osdate "%F %T"
                                          ostime ())))
        local writefile = function (...)
            if select ("#", ...) == 2 then
                chan:write (select (2, ...))
            else
                chan:write (select (1, ...))
            end
        end
        local writefile_nl= function (...)
            chan:write "\n"
            if select ("#", ...) == 2 then
                chan:write (select (2, ...))
            else
                chan:write (select (1, ...))
            end
        end

        local writeln_orig = writeln

        texiowrite    = writefile
        texiowrite_nl = writefile_nl
        writeln       = writefile_nl
        statusln      = dummyfunction

        finalizers[#finalizers+1] = function ()
            chan:write (stringformat ("\nlogging finished at %s\n",
                                      osdate ("%Y-%m-%d %H:%M:%S", --- i. e. osdate "%F %T"
                                              ostime ())))
            chan:close ()
            texiowrite    = texio.write
            texiowrite_nl = texio.write_nl
            writeln       = writeln_orig
        end
    --else --- remains “log”
    end
    return finalizers
end

log.set_logout = set_logout

local format_error_handler
if debug then
    local debugtraceback = debug.traceback
    function format_error_handler (err)
        print ""
        print (stringformat ("luaotfload error: %q", err))
        print (stringformat ("Lua interpreter %s", debugtraceback ()))
        print ""
    end
else
    function format_error_handler (err)
        print ""
        print (stringformat ("luaotfload error: %q", err))
        print "Lua debug module not available; please enable for a backtrace"
        print ""
    end
end

local function basic_logger (category, fmt, ...)
    local res = { module_name, "|", category or "UNKNOWN", ":" }
    if fmt then
        local ok, val = xpcall (stringformat, format_error_handler, fmt, ...)
        if ok then
            res [#res + 1] = val
        else
            res [#res + 1] = stringformat ("ERROR: %q", val)
        end
    end
    texiowrite_nl (logout, tableconcat(res, " "))
end

--- with faux db update with maximum verbosity:
---
---     ---------   --------
---     buffering   time (s)
---     ---------   --------
---     full        4.12
---     line        4.20
---     none        4.39
---     ---------   --------
---

io.stdout:setvbuf "no"
io.stderr:setvbuf "no"

local kill_line = "\r\x1b[K"

if texjob == true then
    --- We imitate the texio.* functions so the output is consistent.
    function writeln (str)
        iowrite "\n"
        iowrite(str)
    end
    function statusln (str)
        if first_status == false then
            iowrite (kill_line)
        else
            iowrite "\n"
        end
        iowrite (str)
    end
else
    function writeln (str)
        iowrite(str)
        iowrite "\n"
    end
    function statusln (str)
        if first_status == false then
            iowrite (kill_line)
        end
        iowrite (str)
    end
end

local function stdout (writer, category, ...)
    local res = { module_name, "|", category, ":" }
    local nargs = select("#", ...)
    if nargs == 0 then
        --writeln tableconcat(res, " ")
        --return
    elseif nargs == 1 then
        res[5] = ... -- around 30% faster than unpack()
    else
        res[5] = stringformat(...)
    end
    writer (tableconcat(res, " "))
end

--- at default (zero), we aim to be quiet
local level_ids = { common  = 1, loading = 2, search  = 3 }

--[[doc--

    The report() logger is used more or less all over luaotfload.
    Its requirements are twofold:

    1) Provide two logging channels, the terminal and the log file;
    2) Allow for control over verbosity levels.

    The first part is addressed by specifying the log *mode* as the
    first argument that can be either “log”, meaning the log file, or
    “both”: log file and stdout. Anything else is taken as referring to
    stdout only.

    Verbosity levels, though not as fine-grained as e.g. Context’s
    system of tracers, allow keeping the logging spam caused by
    different subsystems manageable. By default, luaotfload will not
    emit anything if things are running smoothly on level zero. Only
    warning messages are relayed, while the other messages are skipped
    over. (This is a little sub-optimal performance-wise since the
    function calls to the logger are executed regardless.) The log
    level during a Luatex run can be adjusted by setting the “loglevel”
    field in config.luaotfload, or by calling log.set_loglevel() as
    defined above.

--doc]]--

local report = function (mode, lvl, ...)
    if type(lvl) == "string" then
        lvl = level_ids[lvl]
    end
    if not lvl then lvl = 0 end

    if loglevel >= lvl then
        if mode == "log" then
            basic_logger (...)
        elseif mode == "both" and logout ~= "redirect" then
            basic_logger (...)
            stdout (writeln, ...)
        else
            stdout (writeln, ...)
        end
    end
end

log.report = report

--[[doc--

    status_logger -- Overwrites the most recently printed line of the
    terminal. Its purpose is to provide feedback without spamming
    stdout with irrelevant messages, i.e. when building the database.

    Status logging must be initialized by calling status_start() and
    properly reset via status_stop().

    The arguments low and high indicate the loglevel threshold at which
    linewise and full logging is triggered, respectively. E.g.

            names_status (1, 4, "term", "Hello, world!")

    will print nothing if the loglevel is less than one, reuse the
    current line if the loglevel ranges from one to three inclusively,
    and output the message on a separate line otherwise.

--doc]]--

local status_logger = function (mode, ...)
    if mode == "log" then
        basic_logger (...)
    else
        if mode == "both" and logout ~= "redirect" then
            basic_logger (...)
            stdout (statusln, ...)
        else
            stdout (statusln, ...)
        end
        first_status = false
    end
end

--[[doc--

    status_start -- Initialize status logging. This installs the status
        logger if the loglevel is in the specified range, and the normal
        logger otherwise.  It also resets the first line state which
        causing the next line printed using the status logger to not kill
        the current line.

--doc]]--

local status_writer
local status_low  = 99
local status_high = 99

local function status_start (low, high)
    first_status = true
    status_low   = low
    status_high  = high

    if os.type == "windows" --- Assume broken terminal.
    or os.getenv "TERM" == "dumb"
    then
        status_writer = function (mode, ...)
            report (mode, high, ...)
        end
        return
    end

    if low <= loglevel and loglevel < high then
        status_writer = status_logger
    else
        status_writer = function (mode, ...)
            report (mode, high, ...)
        end
    end
end

--[[doc--

    status_stop -- Finalize a status region by outputting a newline and
    printing a message.

--doc]]--

local status_stop = function (...)
    if first_status == false then
        status_writer(...)
        if texjob == false then
            writeln ""
        end
    end
end

log.names_status = function (...) status_writer (...) end
log.names_status_start = status_start
log.names_status_stop  = status_stop

--[[doc--

    The fontloader comes with the Context logging mechanisms
    inaccessible. Instead, it provides dumb fallbacks based
    on the functions in texio.write*() that can be overridden
    by providing a function texio.reporter().

    The fontloader output can be quite verbose, so we disable
    it entirely by default.

--doc]]--

local function texioreporter (message)
    report ("log", 2, message)
end

texio.reporter = texioreporter
--- vim:shiftwidth=4:expandtab:ft=lua
