using Dates
using Printf

# Try to load HTTP; if not installed, give instruction and exit
try
    @eval using HTTP
catch
    println("HTTP.jl not found. Install it with: julia -e 'using Pkg; Pkg.add(\"HTTP\")'")
    exit(1)
end

# Configuration
const URL = "https://www.xxx.cc"
const TIMEOUT_SECS = 6                # request timeout
const ATTEMPTS_PER_CHECK = 3          # number of HTTP attempts per check
const BACKOFF_BETWEEN_ATTEMPTS = 2    # seconds between attempts
const FAILS_TO_REBOOT = 3             # consecutive failed checks required to trigger reboot
const COOLDOWN_AFTER_REBOOT_SECS = 600  # do not reboot again within this many seconds
const DRY_RUN = true                  # set false to actually reboot (DRY RUN true for testing)
const LOGFILE = "./check_website_reboot_log.txt"  # write logs here and also broadcast
const CHECK_INTERVAL_SECS = 60      # run a check every CHECK_INTERVAL_SECS seconds

# Persist state in current directory as requested
const STATE_FILE = "./check_and_reboot_state.json"

# Simple broadcast helper (safe Cmd construction)
function broadcast_msg(msg::AbstractString)
    try
        if Sys.islinux()
            # Try wall if available by writing to its stdin
            wall_paths = ("/usr/bin/wall", "/bin/wall")
            for p in wall_paths
                if isfile(p)
                    try
                        proc = open(`$p`, "w")
                        try
                            write(proc, msg * "\n")
                        finally
                            close(proc)
                        end
                        return true
                    catch
                        # ignore and try next
                    end
                end
            end
            # Fallback to logger (safe arg passing)
            try
                run(Cmd(["logger", msg]))
                return true
            catch
            end
        elseif Sys.isapple()
            # Use AppleScript notification as a fallback (escape double quotes)
            try
                escaped = replace(msg, "\"" => "\\\"")
                applescript = "display notification \"" * escaped * "\" with title \"check_and_reboot\""
                run(Cmd(["osascript", "-e", applescript]))
                return true
            catch
            end
        elseif Sys.iswindows()
            # Try msg to all sessions (may require privileges); best-effort
            try
                run(Cmd(["msg", "*", msg]))
                return true
            catch
            end
        end
    catch
        # swallow any unexpected errors
    end
    return false
end

# Simple logging (prints, appends to LOGFILE, and broadcasts)
function logmsg(s::AbstractString)
    t = Dates.format(now(), "yyyy-mm-dd HH:MM:SS")
    out = "[$t] $s"
    # write to logfile (append)
    try
        open(LOGFILE, "a") do io
            println(io, out)
        end
    catch e
        # If logfile write fails, fallback to stdout
        println("[$t] (log write failed: $e) $s")
    end
    # Also print to stdout for immediate console visibility
    println(out)
    # Best-effort system broadcast so operators on console see it
    try
        broadcast_msg(out)
    catch
        # ignore broadcast failures
    end
end

# Minimal JSON helper (uses JSON.jl if available, otherwise a tiny fallback)
module JSONHelper
    export parse_obj, write_obj
    function parse_obj(s::String)
        try
            @eval using JSON
            return JSON.parse(s)
        catch
            try
                return eval(Meta.parse(replace(s, "null"=>"nothing")))
            catch
                return Dict{String,Any}()
            end
        end
    end
    function write_obj(io, obj::Dict)
        try
            @eval using JSON
            JSON.print(io, obj)
        catch
            # naive serializer for simple dict of numbers/strings
            print(io, "{")
            first = true
            for (k,v) in obj
                if !first; print(io, ","); end
                first = false
                if isa(v, String)
                    # escape quotes and backslashes minimally
                    esc = replace(replace(v, "\\"=>"\\\\") , "\"" => "\\\"")
                    print(io, "\"$k\":\"$esc\"")
                else
                    print(io, "\"$k\":$v")
                end
            end
            print(io, "}")
        end
    end
end

# State handling: store last_reboot as a DateTime
mutable struct State
    consecutive_fails::Int
    last_reboot::DateTime
end

# Default epoch for "never rebooted" state
const NEVER_REBOOTED = DateTime(1970,1,1)

function load_state()
    try
        if isfile(STATE_FILE)
            s = read(STATE_FILE, String)
            obj = JSONHelper.parse_obj(s)
            cf = haskey(obj, "consecutive_fails") ? Int(obj["consecutive_fails"]) : 0
            lr = NEVER_REBOOTED
            if haskey(obj, "last_reboot") && isa(obj["last_reboot"], String)
                try
                    lr = DateTime(obj["last_reboot"])  # expects ISO-like string
                catch
                    # ignore parse error, keep NEVER_REBOOTED
                end
            end
            return State(cf, lr)
        end
    catch e
        logmsg("Warning loading state: $e")
    end
    return State(0, NEVER_REBOOTED)
end

# Atomic save_state to avoid partial/corrupted state across reboots
function save_state(st::State)
    # write ISO-8601 string for DateTime
    lr_str = Dates.format(st.last_reboot, Dates.ISODateTime)
    obj = Dict("consecutive_fails" => st.consecutive_fails,
               "last_reboot" => lr_str)
    tmp = STATE_FILE * ".tmp"
    try
        open(tmp, "w") do io
            JSONHelper.write_obj(io, obj)
        end
        mv(tmp, STATE_FILE; force=true)
    catch e
        logmsg("Warning: failed to write/replace state file: $e")
        # attempt best-effort cleanup
        try
            isfile(tmp) && rm(tmp)
        catch
        end
    end
end

# Helper: system uptime on Linux (seconds), Inf on other OS or error
function system_uptime_seconds()
    try
        if Sys.islinux()
            s = read("/proc/uptime", String)
            return parse(Float64, split(s)[1])
        end
    catch
    end
    return Inf
end

# HTTP check
function check_url_once(url::AbstractString; timeout=TIMEOUT_SECS)
    try
        resp = HTTP.request("GET", url; connect_timeout=timeout, read_timeout=timeout)
        return 200 <= resp.status < 400, resp.status
    catch e
        return false, nothing
    end
end

# Reboot command selection
# Return a tuple of strings (program and args) suitable for constructing Cmd
function reboot_command()
    if Sys.iswindows()
        return ("/usr/bin/cmd", "/C", "shutdown /r /t 0")
    elseif Sys.isapple()
        return ("/usr/bin/sudo", "shutdown", "-r", "now")
    elseif Sys.islinux()
        if isfile("/bin/systemctl") || isfile("/usr/bin/systemctl")
            return ("/usr/bin/sudo", "systemctl", "reboot")
        else
            return ("/usr/bin/sudo", "reboot")
        end
    else
        return nothing
    end
end

function do_reboot()
    cmd = reboot_command()
    if cmd === nothing
        logmsg("Reboot not supported on this OS")
        return false
    end

    # Build a readable command string for logs (escape each arg safely)
    cmd_str = join(map(x -> replace(x, '"' => "\\\""), cmd), " ")

    if DRY_RUN
        logmsg("DRY RUN: would run reboot command: $cmd_str")
        return true
    end

    logmsg("Executing reboot command: $cmd_str")
    try
        # Construct a Cmd from an array so arguments are passed directly (no shell)
        cmd_array = collect(cmd)           # Tuple{String,...} -> Vector{String}
        run(Cmd(cmd_array))
        return true
    catch e
        logmsg("Failed to execute reboot command: $e")
        return false
    end
end

# Single check iteration
function perform_check!(st::State)
    # If we're still within cooldown after a reboot, skip checks
    if st.last_reboot != NEVER_REBOOTED
        elapsed = now() - st.last_reboot
        if elapsed < Second(COOLDOWN_AFTER_REBOOT_SECS)
            remaining = Int(clamp(round((Second(COOLDOWN_AFTER_REBOOT_SECS) - elapsed).value), 0, typemax(Int)))
            logmsg("In cooldown after recent reboot; skipping check for $remaining more seconds.")
            return
        end
    end

    # Boot grace: skip checks if system just booted (helps prevent immediate reboots while services settle)
    upt = system_uptime_seconds()
    if Sys.islinux() && upt < 120
        logmsg("System boot grace active (uptime=$(round(upt))s); skipping check until uptime >= 120s.")
        return
    end

    success = false
    last_code = nothing
    for i in 1:ATTEMPTS_PER_CHECK
        ok, code = check_url_once(URL)
        last_code = code
        if ok
            success = true
            break
        end
        sleep(BACKOFF_BETWEEN_ATTEMPTS)
    end

    if success
        if st.consecutive_fails > 0
            logmsg("Website reachable; resetting consecutive failure counter.")
        else
            logmsg("Website reachable.")
        end
        st.consecutive_fails = 0
        save_state(st)
        return
    else
        st.consecutive_fails += 1
        logmsg(@sprintf("Website unreachable (last HTTP status: %s). Consecutive fails: %d/%d.",
                        isnothing(last_code) ? "no response" : string(last_code),
                        st.consecutive_fails, FAILS_TO_REBOOT))
        save_state(st)
    end

    if st.consecutive_fails >= FAILS_TO_REBOOT
        st.last_reboot = now()
        save_state(st)
        ok = do_reboot()
        if ok
            logmsg("Reboot executed (or simulated). Resetting failure counter.")
            st.consecutive_fails = 0
            save_state(st)
        else
            logmsg("Reboot attempt failed; will retry after next interval.")
        end
    end
end

# Main loop: runs indefinitely every CHECK_INTERVAL_SECS
function main_loop()
    logmsg("Starting check loop. Checking every $(CHECK_INTERVAL_SECS) seconds.")
    logmsg("STATE_FILE path: $(abspath(STATE_FILE))")
    st = load_state()
    # Log loaded state for visibility
    age = st.last_reboot == NEVER_REBOOTED ? "never" : string(Int(round((now() - st.last_reboot).value)))
    lr_str = st.last_reboot == NEVER_REBOOTED ? "never" : Dates.format(st.last_reboot, Dates.ISODateTime)
    logmsg("Loaded state: consecutive_fails=$(st.consecutive_fails) last_reboot=$(lr_str) (age=${age}s)")
    while true
        try
            perform_check!(st)
        catch e
            logmsg("Error during check: $e")
        end
        sleep(CHECK_INTERVAL_SECS)
    end
end

# Run
main_loop()