local log      = require("scada-common.log")
local mqueue   = require("scada-common.mqueue")
local ppm      = require("scada-common.ppm")
local tcd      = require("scada-common.tcd")
local util     = require("scada-common.util")

local pocket   = require("pocket.pocket")
local renderer = require("pocket.renderer")

local core     = require("graphics.core")

local threads = {}

local MAIN_CLOCK   = 0.5 -- (2Hz,   10 ticks)
local RENDER_SLEEP = 100 -- (100ms, 2 ticks)

local MQ__RENDER_CMD = pocket.MQ__RENDER_CMD
local MQ__RENDER_DATA = pocket.MQ__RENDER_DATA

-- main thread
---@nodiscard
---@param smem pkt_shared_memory
function threads.thread__main(smem)
    ---@class parallel_thread
    local public = {}

    -- execute thread
    function public.exec()
        log.debug("main thread start")

        local loop_clock = util.new_clock(MAIN_CLOCK)

        -- start clock
        loop_clock.start()

        -- load in from shared memory
        local pkt_state    = smem.pkt_state
        local pocket_comms = smem.pkt_sys.pocket_comms
        local sv_wd        = smem.pkt_sys.sv_wd
        local api_wd       = smem.pkt_sys.api_wd
        local nav          = smem.pkt_sys.nav

        -- start connection watchdogs
        sv_wd.feed()
        api_wd.feed()
        log.debug("startup> conn watchdogs started")

        -- event loop
        while true do
            local event, param1, param2, param3, param4, param5 = util.pull_event()

            -- handle event
            if event == "timer" then
                if loop_clock.is_clock(param1) then
                    -- main loop tick

                    -- relink if necessary
                    pocket_comms.link_update()

                    -- update any tasks for the active page
                    local page_tasks = nav.get_current_page().tasks
                    for i = 1, #page_tasks do page_tasks[i]() end

                    loop_clock.start()
                elseif sv_wd.is_timer(param1) then
                    -- supervisor watchdog timeout
                    log.info("supervisor server timeout")
                    pocket_comms.close_sv()
                elseif api_wd.is_timer(param1) then
                    -- coordinator watchdog timeout
                    log.info("coordinator api server timeout")
                    pocket_comms.close_api()
                else
                    -- a non-clock/main watchdog timer event
                    -- notify timer callback dispatcher
                    tcd.handle(param1)
                end
            elseif event == "modem_message" then
                -- got a packet
                local packet = pocket_comms.parse_packet(param1, param2, param3, param4, param5)
                pocket_comms.handle_packet(packet)
            elseif event == "mouse_click" or event == "mouse_up" or event == "mouse_drag" or event == "mouse_scroll" or
                   event == "double_click" then
                -- handle a mouse event
                renderer.handle_mouse(core.events.new_mouse_event(event, param1, param2, param3))
            elseif event == "char" or event == "key" or event == "key_up" then
                -- handle a keyboard event
                renderer.handle_key(core.events.new_key_event(event, param1, param2))
            elseif event == "paste" then
                -- handle a paste event
                renderer.handle_paste(param1)
            end

            -- check for termination request or UI crash
            if event == "terminate" or ppm.should_terminate() then
                log.info("terminate requested, main thread exiting")
                pkt_state.shutdown = true
            elseif not pkt_state.ui_ok then
                pkt_state.shutdown = true
                log.info("terminating due to fatal UI error")
            end

            if pkt_state.shutdown then
                log.info("closing server connections...")
                pocket_comms.close()
                log.info("connections closed")
                break
            end
        end
    end

    -- execute the thread in a protected mode, retrying it on return if not shutting down
    function public.p_exec()
        local pkt_state = smem.pkt_state

        while not pkt_state.shutdown do
            local status, result = pcall(public.exec)
            if status == false then
                log.fatal(util.strval(result))
            end

            -- if status is true, then we are probably exiting, so this won't matter
            -- this thread cannot be slept because it will miss events (namely "terminate")
            if not pkt_state.shutdown then
                log.info("main thread restarting now...")
            end
        end
    end

    return public
end

-- pocket renderer thread, tasked with long duration draws
---@nodiscard
---@param smem pkt_shared_memory
function threads.thread__render(smem)
    ---@class parallel_thread
    local public = {}

    -- execute thread
    function public.exec()
        log.debug("render thread start")

        -- load in from shared memory
        local pkt_state    = smem.pkt_state
        local nav          = smem.pkt_sys.nav
        local render_queue = smem.q.mq_render

        local last_update = util.time()

        -- thread loop
        while true do
            -- check for messages in the message queue
            while render_queue.ready() and not pkt_state.shutdown do
                local msg = render_queue.pop()

                if msg ~= nil then
                    if msg.qtype == mqueue.TYPE.COMMAND then
                        -- received a command
                        if msg.message == MQ__RENDER_CMD.UNLOAD_SV_APPS then
                        elseif msg.message == MQ__RENDER_CMD.UNLOAD_API_APPS then
                        end
                    elseif msg.qtype == mqueue.TYPE.DATA then
                        -- received data
                        local cmd = msg.message ---@type queue_data

                        if cmd.key == MQ__RENDER_DATA.LOAD_APP then
                            log.debug("RENDER: load app " .. cmd.val)

                            local draw_start = util.time_ms()

                            pkt_state.ui_ok, pkt_state.ui_error = pcall(function () nav.load_app(cmd.val) end)
                            if not pkt_state.ui_ok then
                                log.fatal(util.c("RENDER: app load failed with error ", pkt_state.ui_error))
                            else
                                log.debug("RENDER: app loaded in " .. (util.time_ms() - draw_start) .. "ms")
                            end
                        end
                    elseif msg.qtype == mqueue.TYPE.PACKET then
                        -- received a packet
                    end
                end

                -- quick yield
                util.nop()
            end

            -- check for termination request
            if pkt_state.shutdown then
                log.info("render thread exiting")
                break
            end

            -- delay before next check
            last_update = util.adaptive_delay(RENDER_SLEEP, last_update)
        end
    end

    -- execute the thread in a protected mode, retrying it on return if not shutting down
    function public.p_exec()
        local pkt_state = smem.pkt_state

        while not pkt_state.shutdown do
            local status, result = pcall(public.exec)
            if status == false then
                log.fatal(util.strval(result))
            end

            if not pkt_state.shutdown then
                log.info("render thread restarting in 5 seconds...")
                util.psleep(5)
            end
        end
    end

    return public
end

return threads