module("luci.controller.netstat", package.seeall)
local nixio = require("nixio")
local uci   = require("luci.model.uci").cursor()

function index()
    entry({"admin", "tools", "get_netdev_stats"}, call("getNetdevStats"), nil).sysauth = false
end

-- Reads /proc/net/dev and returns per-interface rx/tx byte counters.
function getNetdevStats()
    local f = io.open("/proc/net/dev", "r")
    if not f then
        luci.http.prepare_content("application/json")
        luci.http.write('{"stats":{},"ip":"N/A","status":"Disconnected"}')
        return
    end
    local content = f:read("*a")
    f:close()

    local stats = {}
    for line in content:gmatch("[^\n]+") do
        local iface, values = line:match("^%s*([^:]+):%s+(.*)$")
        if iface and values then
            local nums = {}
            for num in values:gmatch("%d+") do
                table.insert(nums, tonumber(num))
            end
            if #nums >= 9 then
                stats[iface] = { rx = nums[1], tx = nums[9] }
            end
        end
    end

    -- Quick connectivity check
    local status = "Disconnected"
    for iface, data in pairs(stats) do
        if iface ~= "lo" and (data.rx > 0 or data.tx > 0) then
            status = "Connected"
            break
        end
    end

    -- ── IP detection ─────────────────────────────────────────────────────────
    -- Strategy: try a single fast HTTP call first (2 s timeout), then fall
    -- back to local ubus/ifstatus which is instant.  The old code tried 11
    -- commands with 4 s timeouts each – worst-case 44 s of blocking.

    local function read_cmd(cmd)
        local p = io.popen(cmd)
        if not p then return nil end
        local line = p:read("*l")
        p:close()
        if not line then return nil end
        line = line:gsub("^%s+",""):gsub("%s+$","")
        return line ~= "" and line or nil
    end

    -- ── Preferred interface resolution ──────────────────────────────────────
    -- The "Preferred Interface" setting may hold either a real netdev name
    -- (e.g. "eth2", "wwan0_1") or a logical/config interface name (e.g.
    -- "modem", "wan") that has no matching key in /proc/net/dev. In the
    -- latter case resolve it to its actual l3_device via ubus so traffic
    -- stats can be found.
    local prefer_iface = ""
    do
        local prefer = uci:get_first("netstats", "config", "prefer") or ""
        -- Only allow safe characters before using it in a shell command.
        if prefer ~= "" and prefer:match("^[%w%-%._]+$") then
            if stats[prefer] then
                prefer_iface = prefer
            else
                local l3 = read_cmd(
                    "ubus call network.interface." .. prefer ..
                    " status 2>/dev/null | jsonfilter -e '@.l3_device'"
                )
                if l3 and stats[l3] then
                    prefer_iface = l3
                end
            end
        end
        -- Nothing configured (or unresolvable): use the default-route device
        -- so idle interfaces named "wan"/"eth1" don't win over the real uplink.
        if prefer_iface == "" then
            local dev = read_cmd("ip route show default 2>/dev/null | awk '{for(i=1;i<NF;i++) if($i==\"dev\"){print $(i+1); exit}}'")
            if dev and dev:match("^[%w%-%._]+$") and stats[dev] then
                prefer_iface = dev
            end
        end
    end

    local function is_valid_ip(v)
        if not v then return false end
        local a,b,c,d = v:match("^(%d+)%.(%d+)%.(%d+)%.(%d+)$")
        if a and b and c and d then
            a,b,c,d = tonumber(a),tonumber(b),tonumber(c),tonumber(d)
            if a<=255 and b<=255 and c<=255 and d<=255 then return true end
        end
        if v:find(":",1,true) and v:match("^[%x:]+$") then return true end
        return false
    end

    local ip = "N/A"

    -- Determine whether the caller wants a public IP (slow, requires network)
    -- or just the fast local WAN address.  The JS frontend sends ?fast=1 for
    -- poll ticks and omits it only when explicitly requesting a public IP refresh.
    local want_public = luci.http.formvalue("fast") ~= "1"

    -- 1. Try public-IP APIs (only when not in fast mode)
    if want_public then
        local public_cmds = {
            "curl -fsS --max-time 1 'https://api.ipify.org' 2>/dev/null",
            "curl -fsS --max-time 1 'http://api.ipify.org' 2>/dev/null",
            "uclient-fetch -qO- --timeout=1 'https://api.ipify.org' 2>/dev/null",
        }
        for _, cmd in ipairs(public_cmds) do
            local v = read_cmd(cmd)
            if is_valid_ip(v) then ip = v; break end
        end
    end

    -- 2. Fall back to local WAN address (instant, no network needed)
    if ip == "N/A" then
        local local_cmds = {
            -- wan IPv4
            "ubus call network.interface.wan status 2>/dev/null | jsonfilter -e '@[\"ipv4-address\"][0].address'",
            "ifstatus wan 2>/dev/null | jsonfilter -e '@[\"ipv4-address\"][0].address'",
            -- wan IPv6
            "ubus call network.interface.wan status 2>/dev/null | jsonfilter -e '@[\"ipv6-address\"][0].address'",
            "ubus call network.interface.wan6 status 2>/dev/null | jsonfilter -e '@[\"ipv6-address\"][0].address'",
        }
        for _, cmd in ipairs(local_cmds) do
            local v = read_cmd(cmd)
            if is_valid_ip(v) then ip = v; break end
        end
    end

    -- ── System uptime ─────────────────────────────────────────────────────────
    local uptime_sec = 0
    local uf = io.open("/proc/uptime", "r")
    if uf then
        local line = uf:read("*l")
        uf:close()
        if line then
            uptime_sec = math.floor(tonumber(line:match("^([%d%.]+)")) or 0)
        end
    end

    -- ── CPU usage (two reads 200 ms apart for accurate delta) ────────────────
    local cpu_pct = 0
    local function read_cpu_stat()
        local f = io.open("/proc/stat", "r")
        if not f then return nil end
        local line = f:read("*l"); f:close()
        local vals = {}
        for n in line:gmatch("%d+") do vals[#vals+1] = tonumber(n) end
        if #vals < 4 then return nil end
        local idle, total = vals[4], 0
        for _, v in ipairs(vals) do total = total + v end
        return { idle = idle, total = total }
    end
    local s1 = read_cpu_stat()
    if s1 then
        nixio.nanosleep(0, 200000000)
        local s2 = read_cpu_stat()
        if s2 then
            local d_total = s2.total - s1.total
            local d_idle  = s2.idle  - s1.idle
            if d_total > 0 then
                cpu_pct = math.floor((d_total - d_idle) / d_total * 100 + 0.5)
            end
        end
    end

    -- ── Memory usage ──────────────────────────────────────────────────────────
    local mem_total, mem_available, mem_free = 0, 0, 0
    local mf = io.open("/proc/meminfo", "r")
    if mf then
        for line in mf:lines() do
            local k, v = line:match("^(%S+):%s+(%d+)")
            if k == "MemTotal"     then mem_total     = tonumber(v) or 0 end
            if k == "MemAvailable" then mem_available = tonumber(v) or 0 end
            if k == "MemFree"      then mem_free      = tonumber(v) or 0 end
        end
        mf:close()
    end
    -- MemAvailable is present on Linux 3.14+; fall back to MemFree on older kernels
    if mem_available == 0 and mem_free > 0 then mem_available = mem_free end
    local mem_pct = 0
    if mem_total > 0 then
        mem_pct = math.floor((mem_total - mem_available) / mem_total * 100 + 0.5)
    end
    -- used MB and total MB for display
    local mem_used_mb  = math.floor((mem_total - mem_available) / 1024 + 0.5)
    local mem_total_mb = math.floor(mem_total / 1024 + 0.5)

    -- ── Disk space (root filesystem) ──────────────────────────────────────────
    local disk_pct, disk_used_mb, disk_total_mb = 0, 0, 0
    local df = read_cmd("df -k / 2>/dev/null | awk 'NR==2{print $2,$3}'")
    if df then
        local dtotal, dused = df:match("^(%d+)%s+(%d+)$")
        dtotal = tonumber(dtotal) or 0
        dused  = tonumber(dused)  or 0
        if dtotal > 0 then
            disk_pct      = math.floor(dused / dtotal * 100 + 0.5)
            disk_used_mb  = math.floor(dused  / 1024 + 0.5)
            disk_total_mb = math.floor(dtotal / 1024 + 0.5)
        end
    end

    -- ── CPU temperature ───────────────────────────────────────────────────────
    local cpu_temp = nil
    -- Scan all available thermal zones and pick the highest valid reading
    -- (avoids hardcoded zone numbers which vary per device)
    for zone = 0, 9 do
        local path = "/sys/class/thermal/thermal_zone" .. zone .. "/temp"
        local tf = io.open(path, "r")
        if tf then
            local val = tf:read("*l")
            tf:close()
            local t = tonumber(val)
            if t and t > 0 then
                -- values > 1000 are in millidegrees
                if t > 1000 then t = t / 1000 end
                t = math.floor(t + 0.5)
                -- Keep the highest temperature reading across all zones
                if cpu_temp == nil or t > cpu_temp then
                    cpu_temp = t
                end
            end
        end
    end

    luci.http.prepare_content("application/json")
    luci.http.write_json({ stats = stats, ip = ip, status = status,
                           prefer_iface = prefer_iface,
                           uptime      = uptime_sec,
                           cpu_pct     = cpu_pct,
                           cpu_temp    = cpu_temp,
                           mem_pct     = mem_pct,
                           mem_used    = mem_used_mb,
                           mem_total   = mem_total_mb,
                           disk_pct    = disk_pct,
                           disk_used   = disk_used_mb,
                           disk_total  = disk_total_mb })
end