# Nimbus - Fetch account and storage states from peers efficiently
#
# Copyright (c) 2021 Status Research & Development GmbH
# Licensed under either of
#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
#    http://www.apache.org/licenses/LICENSE-2.0)
#  * MIT license ([LICENSE-MIT](LICENSE-MIT) or
#    http://opensource.org/licenses/MIT)
# at your option. This file may not be copied, modified, or distributed
# except according to those terms.

{.push raises: [].}

import
  std/[options, strformat, strutils],
  chronos,
  chronicles,
  eth/[common, p2p],
  stint,
  ../../../utils/prettify,
  ../../misc/timer_helper,
  ../../types

logScope:
  topics = "snap-tick"

type
  TickerSnapStatsUpdater* = proc: TickerSnapStats {.gcsafe, raises: [].}
    ## Snap sync state update function

  TickerFullStatsUpdater* = proc: TickerFullStats {.gcsafe, raises: [].}
    ## Full sync state update function

  SnapDescDetails = object
    ## Private state descriptor
    snapCb: TickerSnapStatsUpdater
    recovery: bool
    lastRecov: bool
    lastStats: TickerSnapStats

  FullDescDetails = object
    ## Private state descriptor
    fullCb: TickerFullStatsUpdater
    lastStats: TickerFullStats

  TickerSnapStats* = object
    ## Snap sync state (see `TickerSnapStatsUpdater`)
    beaconBlock*: Option[BlockNumber]
    pivotBlock*: Option[BlockNumber]
    nAccounts*: (float,float)          ## Mean and standard deviation
    accountsFill*: (float,float,float) ## Mean, standard deviation, merged total
    nAccountStats*: int                ## #chunks
    nSlotLists*: (float,float)         ## Mean and standard deviation
    nContracts*: (float,float)         ## Mean and standard deviation
    nStorageQueue*: Option[int]
    nContractQueue*: Option[int]
    nQueues*: int

  TickerFullStats* = object
    ## Full sync state (see `TickerFullStatsUpdater`)
    pivotBlock*: Option[BlockNumber]
    topPersistent*: BlockNumber
    nextUnprocessed*: Option[BlockNumber]
    nextStaged*: Option[BlockNumber]
    nStagedQueue*: int
    suspended*: bool
    reOrg*: bool

  TickerRef* = ref object
    ## Ticker descriptor object
    nBuddies: int
    logTicker: TimerCallback
    started: Moment
    visited: Moment
    prettyPrint: proc(t: TickerRef) {.gcsafe, raises: [].}
    case fullMode: bool
    of false:
      snap: SnapDescDetails
    of true:
      full: FullDescDetails

const
  extraTraceMessages = false # or true
    ## Enabled additional logging noise

  tickerStartDelay = chronos.milliseconds(100)
  tickerLogInterval = chronos.seconds(1)
  tickerLogSuppressMax = chronos.seconds(100)

# ------------------------------------------------------------------------------
# Private functions: pretty printing
# ------------------------------------------------------------------------------

proc pc99(val: float): string =
  if 0.99 <= val and val < 1.0: "99%"
  elif 0.0 < val and val <= 0.01: "1%"
  else: val.toPC(0)

proc toStr(a: Option[int]): string =
  if a.isNone: "n/a"
  else: $a.unsafeGet

# ------------------------------------------------------------------------------
# Private functions: printing ticker messages
# ------------------------------------------------------------------------------

template logTxt(info: static[string]): static[string] =
  "Ticker " & info

template noFmtError(info: static[string]; code: untyped) =
  try:
    code
  except ValueError as e:
    raiseAssert "Inconveivable (" & info & "): " & e.msg

proc snapTicker(t: TickerRef) {.gcsafe.} =
  let
    data = t.snap.snapCb()
    now = Moment.now()

  if data != t.snap.lastStats or
     t.snap.recovery != t.snap.lastRecov or
     tickerLogSuppressMax < (now - t.visited):
    var
      nAcc, nSto, nCon: string
      pv = "n/a"
    let
      nStoQ = data.nStorageQueue.toStr
      nConQ = data.nContractQueue.toStr
      bc = data.beaconBlock.toStr
      recoveryDone = t.snap.lastRecov
      accCov = data.accountsFill[0].pc99 &
         "(" & data.accountsFill[1].pc99 & ")" &
         "/" & data.accountsFill[2].pc99 &
         "~" & data.nAccountStats.uint.toSI
      nInst = t.nBuddies

      # With `int64`, there are more than 29*10^10 years range for seconds
      up = (now - t.started).seconds.uint64.toSI
      mem = getTotalMem().uint.toSI

    t.snap.lastStats = data
    t.visited = now
    t.snap.lastRecov = t.snap.recovery

    if data.pivotBlock.isSome:
      pv = data.pivotBlock.toStr & "/" & $data.nQueues

    noFmtError("runLogTicker"):
      nAcc = (&"{(data.nAccounts[0]+0.5).int64}" &
              &"({(data.nAccounts[1]+0.5).int64})")
      nSto = (&"{(data.nSlotLists[0]+0.5).int64}" &
              &"({(data.nSlotLists[1]+0.5).int64})")
      nCon = (&"{(data.nContracts[0]+0.5).int64}" &
              &"({(data.nContracts[1]+0.5).int64})")

    if t.snap.recovery:
      info "Snap sync statistics (recovery)",
        up, nInst, bc, pv, nAcc, accCov, nSto, nStoQ, nCon, nConQ, mem
    elif recoveryDone:
      info "Snap sync statistics (recovery done)",
        up, nInst, bc, pv, nAcc, accCov, nSto, nStoQ, nCon, nConQ, mem
    else:
      info "Snap sync statistics",
        up, nInst, bc, pv, nAcc, accCov, nSto, nStoQ, nCon, nConQ, mem


proc fullTicker(t: TickerRef) {.gcsafe.} =
  let
    data = t.full.fullCb()
    now = Moment.now()

  if data != t.full.lastStats or
     tickerLogSuppressMax < (now - t.visited):
    let
      persistent = data.topPersistent.toStr
      staged = data.nextStaged.toStr
      unprocessed = data.nextUnprocessed.toStr
      queued = data.nStagedQueue
      reOrg = if data.reOrg: "t" else: "f"
      pv = data.pivotBlock.toStr

      nInst = t.nBuddies

      # With `int64`, there are more than 29*10^10 years range for seconds
      up = (now - t.started).seconds.uint64.toSI
      mem = getTotalMem().uint.toSI

    t.full.lastStats = data
    t.visited = now

    if data.suspended:
      info "Full sync statistics (suspended)", up, nInst, pv,
        persistent, unprocessed, staged, queued, reOrg, mem
    else:
      info "Full sync statistics", up, nInst, pv,
        persistent, unprocessed, staged, queued, reOrg, mem

# ------------------------------------------------------------------------------
# Private functions: ticking log messages
# ------------------------------------------------------------------------------

proc setLogTicker(t: TickerRef; at: Moment) {.gcsafe.}

proc runLogTicker(t: TickerRef) {.gcsafe.} =
  t.prettyPrint(t)
  t.setLogTicker(Moment.fromNow(tickerLogInterval))

proc setLogTicker(t: TickerRef; at: Moment) =
  if t.logTicker.isNil:
    when extraTraceMessages:
      debug logTxt "was stopped", fullMode=t.fullMode, nBuddies=t.nBuddies
  else:
    t.logTicker = safeSetTimer(at, runLogTicker, t)

proc initImpl(t: TickerRef; cb: TickerSnapStatsUpdater) =
  t.fullMode = false
  t.prettyPrint = snapTicker
  t.snap = SnapDescDetails(snapCb: cb)

proc initImpl(t: TickerRef; cb: TickerFullStatsUpdater) =
  t.fullMode = true
  t.prettyPrint = fullTicker
  t.full = FullDescDetails(fullCb: cb)

proc startImpl(t: TickerRef) =
  t.logTicker = safeSetTimer(Moment.fromNow(tickerStartDelay),runLogTicker,t)
  if t.started == Moment.default:
    t.started = Moment.now()

proc stopImpl(t: TickerRef) =
  ## Stop ticker unconditionally
  t.logTicker = nil

# ------------------------------------------------------------------------------
# Public constructor and start/stop functions
# ------------------------------------------------------------------------------

proc init*(T: type TickerRef; cb: TickerSnapStatsUpdater): T =
  ## Constructor
  new result
  result.initImpl(cb)

proc init*(t: TickerRef; cb: TickerSnapStatsUpdater) =
  ## Re-initialise ticket
  if not t.isNil:
    t.visited.reset
    if t.fullMode:
      t.prettyPrint(t) # print final state for full sync
    t.initImpl(cb)

proc init*(t: TickerRef; cb: TickerFullStatsUpdater) =
  ## Re-initialise ticket
  if not t.isNil:
    t.visited.reset
    if not t.fullMode:
      t.prettyPrint(t) # print final state for snap sync
    t.initImpl(cb)

proc start*(t: TickerRef) =
  ## Re/start ticker unconditionally
  if not t.isNil:
    when extraTraceMessages:
      debug logTxt "start", fullMode=t.fullMode, nBuddies=t.nBuddies
    t.startImpl()

proc stop*(t: TickerRef) =
  ## Stop ticker unconditionally
  if not t.isNil:
    t.stopImpl()
    when extraTraceMessages:
      debug logTxt "stop", fullMode=t.fullMode, nBuddies=t.nBuddies

# ------------------------------------------------------------------------------
# Public functions
# ------------------------------------------------------------------------------

proc startBuddy*(t: TickerRef) =
  ## Increment buddies counter and start ticker unless running.
  if not t.isNil:
    if t.nBuddies <= 0:
      t.nBuddies = 1
      if not t.fullMode and not t.snap.recovery:
        t.startImpl()
        when extraTraceMessages:
          debug logTxt "start buddy", fullMode=t.fullMode, nBuddies=t.nBuddies
    else:
      t.nBuddies.inc

proc startRecovery*(t: TickerRef) =
  ## Ditto for recovery mode
  if not t.isNil and not t.fullMode and not t.snap.recovery:
    t.snap.recovery = true
    if t.nBuddies <= 0:
      t.startImpl()
      when extraTraceMessages:
        debug logTxt "start recovery", fullMode=t.fullMode, nBuddies=t.nBuddies

proc stopBuddy*(t: TickerRef) =
  ## Decrement buddies counter and stop ticker if there are no more registered
  ## buddies.
  if not t.isNil:
    t.nBuddies.dec
    if t.nBuddies <= 0 and not t.fullMode and not t.snap.recovery:
      t.stopImpl()
      when extraTraceMessages:
        debug logTxt "stop (buddy)", fullMode=t.fullMode, nBuddies=t.nBuddies

proc stopRecovery*(t: TickerRef) =
  ## Ditto for recovery mode
  if not t.isNil and not t.fullMode and t.snap.recovery:
    t.snap.recovery = false
    t.stopImpl()
    when extraTraceMessages:
      debug logTxt "stop (recovery)", fullMode=t.fullMode, nBuddies=t.nBuddies

# ------------------------------------------------------------------------------
# End
# ------------------------------------------------------------------------------