import React, { useCallback, useEffect, useState } from 'react'
import { api, Proc, ProcTable } from './api'
import { fmtBytes, fmtRate } from './Dashboard'
import { Btn, Loading, toast } from './ui'
import { useRefreshMs } from './prefs'

type Col = 'cpu' | 'rss' | 'pid' | 'name' | 'user' | 'started' | 'cpu_time'
const pct = (v: number) => `${Math.round(v)}%`
const fmtUptime = (s: number) => { const d = Math.floor(s / 86400), h = Math.floor((s % 86400) / 3600), m = Math.floor((s % 3600) / 60); return d > 0 ? `${d}d ${h}h` : h > 0 ? `${h}h ${m}m` : `${m}m` }
const fmtDur = (s: number) => (s >= 3600 ? `${Math.floor(s / 3600)}h${String(Math.floor((s % 3600) / 60)).padStart(2, '0')}` : s >= 60 ? `${Math.floor(s / 60)}m${String(Math.floor(s % 60)).padStart(2, '0')}` : `${s.toFixed(1)}s`)
const fmtStart = (ms: number) => { const d = new Date(ms), now = new Date(); return d.toDateString() === now.toDateString() ? d.toLocaleTimeString([], { hour: '2-digit', minute: '2-digit' }) : d.toLocaleDateString(undefined, { month: 'short', day: '2-digit' }) }
const STATE: Record<string, string> = { R: 'running', S: 'sleeping', D: 'disk wait', Z: 'zombie', T: 'stopped', t: 'traced', I: 'idle' }

const BLOCKS = '▁▂▃▄▅▆▇█'

// btop-style gradient bar: the track carries the green→yellow→red gradient and a cover
// from the right hides the unfilled part, so colour depends on position not on level.
function GBar({ frac }: { frac: number }) {
  return <div className="gbar"><div className="gcover" style={{ width: `${100 - Math.min(100, Math.max(0, frac * 100))}%` }} /></div>
}
function Row({ label, frac, value }: { label: string; frac: number; value: string }) {
  return <div className="brow"><span className="bl">{label}</span><GBar frac={frac} /><span className="bv">{value}</span></div>
}
// Block-character graph, coloured per column by its value, like btop's cpu graph.
function Graph({ values, max = 100 }: { values: number[]; max?: number }) {
  const cols = 60
  const v = values.slice(-cols)
  const pad = cols - v.length
  return (
    <div className="graph" aria-hidden="true">
      {pad > 0 && <span className="gpad">{'\u2581'.repeat(pad)}</span>}
      {v.map((x, i) => { const f = Math.min(1, Math.max(0, x / max)); return <span key={i} className={f >= 0.8 ? 'g3' : f >= 0.5 ? 'g2' : 'g1'}>{BLOCKS[Math.min(7, Math.round(f * 7))]}</span> })}
    </div>
  )
}
function Box({ title, right, children, className = '' }: { title: string; right?: string; children: React.ReactNode; className?: string }) {
  return <section className={'box ' + className}><span className="box-title">{title}</span>{right && <span className="box-right">{right}</span>}{children}</section>
}

export default function Procs() {
  const [t, setT] = useState<ProcTable | null>(null)
  const [err, setErr] = useState('')
  const [sort, setSort] = useState<Col>('cpu')
  const [asc, setAsc] = useState(false)
  const [q, setQ] = useState('')
  const [mine, setMine] = useState(false)
  const [sel, setSel] = useState<number | null>(null)
  const [paused, setPaused] = useState(false)
  const [showTop, setShowTop] = useState<boolean>(() => localStorage.getItem('hamlab.procs.top') !== '0')
  const interval = useRefreshMs()

  const load = useCallback(async () => {
    try { setT(await api.procs()); setErr('') } catch (e) { setErr(e instanceof Error ? e.message : 'failed') }
  }, [])
  useEffect(() => {
    load()
    const id = window.setInterval(() => { if (!paused && document.visibilityState === 'visible') load() }, interval)
    return () => window.clearInterval(id)
  }, [load, paused, interval])

  const head = (c: Col, label: string, cls = '') => (
    <button className={'th ' + cls + (sort === c ? ' on' : '')} title={{ cpu: 'share of one core, right now', rss: 'resident memory (RSS)', cpu_time: 'total CPU time used since it started', started: 'when the process started', pid: 'process id', name: 'program name', user: 'owner' }[c]} onClick={() => { if (sort === c) setAsc(!asc); else { setSort(c); setAsc(c === 'name' || c === 'user' || c === 'pid') } }}>
      {label}{sort === c ? (asc ? ' ▲' : ' ▼') : ''}
    </button>
  )

  if (!t) return <div className="dash">{err ? <div className="error">{err}</div> : <Loading label="Reading processes…" />}</div>
  const needle = q.trim().toLowerCase()
  const rows = t.procs
    .filter((p) => (!needle || p.name.toLowerCase().includes(needle) || (p.cmd ?? '').toLowerCase().includes(needle) || p.user.toLowerCase().includes(needle) || String(p.pid) === needle) && (!mine || p.user !== 'root'))
    .sort((a, b) => {
      const va = a[sort] as number | string, vb = b[sort] as number | string
      const r = typeof va === 'string' ? (va as string).localeCompare(vb as string) : (va as number) - (vb as number)
      return asc ? r : -r
    })
  const selected = sel !== null ? t.procs.find((p) => p.pid === sel) : undefined
  const memFrac = t.mem.total ? t.mem.used / t.mem.total : 0
  const swapFrac = t.swap.total ? t.swap.used / t.swap.total : 0

  const signal = async (p: Proc, sig: 'TERM' | 'KILL') => {
    if (!window.confirm(`Send SIG${sig} to ${p.name} (pid ${p.pid})?`)) return
    try { await api.procSignal(p.pid, sig); toast(`SIG${sig} sent to ${p.name}`); load() } catch (e) { toast(e instanceof Error ? e.message : 'failed', 'err') }
  }

  return (
    <div className="procs-page">
      {showTop && <div className="procs-top">
        <Box title="cpu" right={`${t.cpu_model ?? ''}${t.cpu_mhz ? ` · ${(t.cpu_mhz / 1000).toFixed(2)}${t.cpu_max_mhz ? ` / ${(t.cpu_max_mhz / 1000).toFixed(1)}` : ''} GHz` : ''}${t.cpu_temp ? ` · ${t.cpu_temp.toFixed(0)}°C` : ''}`}>
          <div className="cpu-total">
            <Graph values={t.cpu_hist} />
            <div className="cpu-total-v"><span className="bl">CPU</span><span className="bv big">{pct(t.cpu)}</span><span className="muted small">total, all cores</span></div>
          </div>
          <div className="cores">
            {t.cores.map((c, i) => <Row key={i} label={`C${i}`} frac={c / 100} value={pct(c)} />)}
          </div>
          <div className="box-foot muted">
            <span>load avg <b>{t.load[0].toFixed(2)}</b> {t.load[1].toFixed(2)} {t.load[2].toFixed(2)} <small>(1 · 5 · 15 min, {t.cores.length} cores)</small></span>
            <span>up <b>{fmtUptime(t.uptime)}</b></span>
            <span><b>{t.total}</b> tasks, <b>{t.running}</b> running</span>
          </div>
        </Box>
        <Box title="mem" right={`${fmtBytes(t.mem.total)} total`}>
          <Row label="Used" frac={memFrac} value={`${fmtBytes(t.mem.used)} · ${pct(memFrac * 100)}`} />
          <Row label="Available" frac={t.mem.total ? t.mem.avail / t.mem.total : 0} value={fmtBytes(t.mem.avail)} />
          <Row label="Cached" frac={t.mem.total ? (t.mem.cached ?? 0) / t.mem.total : 0} value={fmtBytes(t.mem.cached ?? 0)} />
          <Row label="Free" frac={t.mem.total ? (t.mem.free ?? 0) / t.mem.total : 0} value={fmtBytes(t.mem.free ?? 0)} />
          {t.swap.total > 0 ? (
            <><div className="box-sub">swap · {fmtBytes(t.swap.total)} total</div>
              <Row label="Used" frac={swapFrac} value={`${fmtBytes(t.swap.used)} · ${pct(swapFrac * 100)}`} />
              <Row label="Free" frac={t.swap.total ? t.swap.avail / t.swap.total : 0} value={fmtBytes(t.swap.avail)} /></>
          ) : <div className="box-sub muted">no swap</div>}
          <div className="box-foot muted small">Used = total − available. Cached is file cache the kernel gives back under pressure, so "available" is the honest headroom.</div>
        </Box>
        <Box title="net" className="netbox">
          {t.net.filter((n) => n.up).map((n) => (
            <div className="netrow" key={n.iface}>
              <span className="bl mono">{n.iface}</span>
              <span className="bv"><span className="dn">▼ {fmtRate(n.rx_bps)}</span> <span className="upc">▲ {fmtRate(n.tx_bps)}</span></span>
              <span className="muted small">{fmtBytes(n.rx_total)} in · {fmtBytes(n.tx_total)} out</span>
            </div>
          ))}
          {t.net.filter((n) => n.up).length === 0 && <div className="muted">no interfaces up</div>}
        </Box>
      </div>}
      <div className="procs-sticky">
      <div className="procs-tools">
        <button className={'chip' + (showTop ? ' on' : '')} title="show or hide the cpu/mem/net boxes" onClick={() => { setShowTop(!showTop); localStorage.setItem('hamlab.procs.top', showTop ? '0' : '1') }}>{showTop ? 'metrics ▴' : 'metrics ▾'}</button>
        <input placeholder="filter name, command, user, pid" value={q} onChange={(e) => setQ(e.target.value)} />
        <button className={'chip' + (mine ? ' on' : '')} onClick={() => setMine(!mine)}>hide root</button>
        <button className={'chip' + (paused ? ' on' : '')} onClick={() => setPaused(!paused)}>{paused ? 'paused' : 'live'}</button>
        <span className="muted small">{rows.length} shown</span>
      </div>

      <div className="prow phead">
        {head('pid', 'PID', 'num')}{head('user', 'User')}{head('name', 'Program')}{head('cpu', 'CPU %', 'num')}{head('rss', 'Memory', 'num')}{head('cpu_time', 'CPU time', 'num')}{head('started', 'Started', 'num')}
      </div>
      </div>
      <div className="ptable">
        {rows.map((p) => (
          <div key={p.pid} className={'prow' + (p.pid === sel ? ' active' : '') + (p.state === 'Z' ? ' zombie' : p.state === 'R' ? ' running' : '')} onClick={() => setSel(p.pid === sel ? null : p.pid)} title={p.cmd || p.name}>
            <span className="num muted">{p.pid}</span>
            <span className="ell">{p.user}</span>
            <span className="ell mono">{p.name}{p.threads > 1 && <small className="muted"> ×{p.threads}</small>}</span>
            <span className={'num' + (p.cpu >= 50 ? ' hot' : '')}>{p.cpu.toFixed(1)}</span>
            <span className="num">{fmtBytes(p.rss)}</span>
            <span className="num muted">{fmtDur(p.cpu_time)}</span>
            <span className="num muted">{fmtStart(p.started)}</span>
          </div>
        ))}
      </div>

      {selected && (
        <div className="pdetail">
          <div className="sub-head"><b className="mono">{selected.name}</b><span className="muted">pid {selected.pid} · parent {selected.ppid} · {selected.user} · {STATE[selected.state] ?? selected.state} · nice {selected.nice} · {selected.threads} threads</span><span className="spacer" /><button className="icon-btn" onClick={() => setSel(null)}>✕</button></div>
          <div className="mono cmdline">{selected.cmd || '(kernel thread)'}</div>
          <div className="svc-actions">
            <Btn className="btn" onClick={() => signal(selected, 'TERM')}>Terminate</Btn>
            <Btn className="btn danger" onClick={() => signal(selected, 'KILL')}>Kill −9</Btn>
            <span className="muted">cpu {selected.cpu.toFixed(1)}% · {fmtBytes(selected.rss)} · running {fmtDur(selected.cpu_time)} of cpu since {new Date(selected.started).toLocaleString()}</span>
          </div>
        </div>
      )}
    </div>
  )
}