-- luacheck: globals debuggery whosit minetest futil
-- based on debuggery by flux, but outputs result in chat and calculates max/avg
local f = string.format
local S = debuggery.S

local get_us_time = minetest.get_us_time
local log = debuggery.log
local log_level = minetest.settings:get("debug_log_level") or "action"

local pairs_by_key = futil.table.pairs_by_key

local s = debuggery.settings

whosit = _G.whosit or {}
_G.whosit = whosit

local old_values = whosit.instrument_old_values or {}
whosit.instrument_old_values = old_values
local total_steps = whosit.instrument_total_steps or {}
whosit.instrument_total_steps = total_steps
local total_elapsed = whosit.instrument_total_elapsed or {}
whosit.instrument_total_elapsed = total_elapsed
local total_calls = whosit.instrument_total_calls or {}
whosit.instrument_total_calls = total_calls
local max_time = whosit.instrument_max_time or {}
whosit.instrument_max_time = max_time

local num_instrumented = 0

local function instrument(name, value, _cache)
    if type(value) == "function" then
        log("action", "instrumenting %q", name)
        return function(...)
            if s.instrument_log_every_call then
                log("action", "%s(%s)", name, dump({ ... }))
            end
            local begin = get_us_time()
            local rvs = { value(...) }
            local elapsed = get_us_time() - begin
            total_elapsed[name] = (total_elapsed[name] or 0) + elapsed
            total_calls[name] = (total_calls[name] or 0) + 1
            max_time[name] = math.max(elapsed, max_time[name] or 0)
            -- if s.instrument_log_every_call then
            -- 	log("action", "%s(...) -> %s", name, dump(rvs))
            -- end
            return unpack(rvs)
        end
    elseif type(value) == "table" then
        _cache = _cache or {}
        local cached = _cache[value]
        if cached then
            return cached
        end

        local t = {}
        _cache[value] = t

        for k, v in pairs(value) do
            if type(k) == "string" then
                t[k] = instrument(f("%s.%s", name, k), v, _cache)
            else
                t[k] = instrument(f("%s[%s]", name, k), v, _cache)
            end
        end

        setmetatable(t, instrument(f("getmetatable(%s)", name), getmetatable(value), _cache))

        return t
    else
        return value
    end
end

local function instrument_mod(mod)
    log("action", "instrumenting %s", mod)
    old_values[mod] = _G[mod]
    _G[mod] = instrument(mod, _G[mod])
    num_instrumented = num_instrumented + 1
end

local function uninstrument_mod(mod)
    log("action", "uninstrumenting %s", mod)
    _G[mod] = old_values[mod]
    old_values[mod] = nil
    num_instrumented = num_instrumented - 1
end

minetest.register_chatcommand(
    "whosit_instrument_mod",
    {
        params = S("<global_name>"),
        description = S("toggles recording timing data for all functions declared in a particular global"),
        privs = { [s.admin_priv] = true },
        func = function(name, param)
            if param == "" then
                local mods = {}
                for mod in pairs(old_values) do
                    table.insert(mods, mod)
                end
                if #mods == 0 then
                    return true, S("no mods currently instrumented")
                else
                    return true, S("mods currently instrumented: @1", table.concat(mods, ", "))
                end
            end

            if not (minetest.global_exists(param) and _G[param]) then
                return false, S("unknown global @1", param)
            end

            if old_values[param] then
                uninstrument_mod(param)
                return true, S("instrumentation disabled for @1", param)
            else
                instrument_mod(param)
                return true, S("instrumentation enabled for @1", param)
            end
        end,
})

local function get_modname(fname)
    local dot = fname:find('.',1,true)
    if dot then
        return fname:sub(1, dot - 1)
    else
        return fname
    end
end

function whosit.instrument_summary_lines(perstep)
    if futil.table.is_empty(total_calls) then
        return false, "nothing to report"
    end

    local out = {}
    for name, num_calls in pairs_by_key(total_calls, function(a,b) return total_elapsed[a] > total_elapsed[b] end) do
        local steps = perstep and total_steps[get_modname(name)] or 1
        local te = math.round(total_elapsed[name])
        local avg = total_elapsed[name]/num_calls
        local tm = max_time[name]

        table.insert(out, f("%15.1f | n:%11d | avg:%9.1f | max:%9.1f -- %s()", te/steps, num_calls/steps, avg, tm, name))
    end
    return true, out
end

minetest.register_chatcommand(
    "whosit_instrument_summary",
    {
        -- params = S("<global_name>"),
        -- description = S("toggles recording timing data for all functions declared in a particular global"),
        privs = { [s.admin_priv] = true },
        func = function(name, param)
            if futil.table.is_empty(total_calls) then
                return false, "nothing to report"
            end
            local ok, res = whosit.instrument_summary_lines()
            if ok then
                core.chat_send_player(name, table.concat(res, '\n'))
            end
            return true, "done."
        end,
})


minetest.register_chatcommand(
    "whosit_instrument_reset",
    {
        -- params = S("<global_name>"),
        -- description = S("toggles recording timing data for all functions declared in a particular global"),
        privs = { [s.admin_priv] = true },
        func = function(name, param)
            for name, _ in pairs(total_calls) do
                total_calls[name] = nil
                total_elapsed[name] = nil
                max_time[name] = nil
            end
            for name, _ in pairs(total_steps) do
                total_steps[name] = nil
            end
            return true, "Stats reset."
        end,
})



function whosit.instrument_summary_text(perstep)
    local _,out = whosit.instrument_summary_lines(perstep)
    return table.concat(out, '\n')
end

function whosit.instrument_update_steps()
    for name,_ in pairs(old_values) do
        total_steps[name] = (total_steps[name] or 0) + 1
    end
end

if not whosit.instrument_globalstep_registered then
    minetest.register_globalstep(
        function(_dtime)
            whosit.instrument_update_steps()
        end
    )
    whosit.instrument_globalstep_registered = true
end