# Nimbus
# Copyright (c) 2018-2022 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.

{.used.}

import
  std/[algorithm, sequtils, strformat, strutils, tables],
  unittest2,
  ../stew/keyed_queue,
  ../stew/keyed_queue/kq_debug

const
  lruCacheLimit = 10
  lruCacheModulo = 13

  keyList = [
    185, 208,  53,  54, 196, 189, 187, 117,  94,  29,   6, 173, 207,  45,  31,
    208, 127, 106, 117,  49,  40, 171,   6,  94,  84,  60, 125,  87, 168, 183,
    200, 155,  34,  27,  67, 107, 108, 223, 249,   4, 113,   9, 205, 100,  77,
    224,  19, 196,  14,  83, 145, 154,  95,  56, 236,  97, 115, 140, 134,  97,
    153, 167,  23,  17, 182, 116, 253,  32, 108, 148, 135, 169, 178, 124, 147,
    231, 236, 174, 211, 247,  22, 118, 144, 224,  68, 124, 200,  92,  63, 183,
    56,  107,  45, 180, 113, 233,  59, 246,  29, 212, 172, 161, 183, 207, 189,
    56,  198, 130,  62,  28,  53, 122]

type
  KUQueue = # mind the kqueue module from the nim standard lib
    KeyedQueue[uint,uint]

  LruCache = object
    size: int
    q: KUQueue

let
  noisy = defined(debug)

# ------------------------------------------------------------------------------
# Debugging
# ------------------------------------------------------------------------------

proc `$`(rc: KeyedQueuePair[uint,uint]): string =
  "(" & $rc.key & "," & $rc.data & ")"

proc `$`(rc: Result[KeyedQueuePair[uint,uint],void]): string {.used.} =
  result = "<"
  if rc.isOk:
    result &= $rc.value.key & "," & $rc.value.data
  result &= ">"

proc `$`(rc: Result[uint,void]): string =
  result = "<"
  if rc.isOk:
    result &= $rc.value
  result &= ">"

proc say(noisy = false; pfx = "***"; args: varargs[string, `$`]) =
  if noisy:
    if args.len == 0:
      echo "*** ", pfx
    elif 0 < pfx.len and pfx[^1] != ' ':
      echo pfx, " ", args.toSeq.join
    else:
      echo pfx, args.toSeq.join

# ------------------------------------------------------------------------------
# Converters
# ------------------------------------------------------------------------------

proc toValue(n: int): uint =
  (n + 1000).uint

proc fromValue(n: uint): int =
  (n - 1000).int

proc toKey(n: int): uint =
  n.uint

proc fromKey(n: uint): int =
  n.int

# ------------------------------------------------------------------------------
# Helpers
# ------------------------------------------------------------------------------

proc lruValue(lru: var LruCache; n: int): uint =
  let
    key = n.toKey
    rc = lru.q.lruFetch(key)
  if rc.isOk:
    doAssert key == lru.q.lastKey.value
    doAssert lru.q.verify.isOk
    return rc.value
  result = lru.q.lruAppend(key, key.fromKey.toValue, lru.size)
  doAssert lru.q.verify.isOk

proc toLruCache(a: openArray[int]): LruCache =
  result.size = lruCacheLimit
  for n in a.toSeq.mapIt(it mod lruCacheModulo):
    doAssert result.lruValue(n) == n.toValue

proc toQueue(a: openArray[int]): KUQueue =
  for n in a:
    result[n.toKey] = n.toValue

proc toUnique(a: openArray[int]): seq[uint] =
  var q = a.toQueue
  toSeq(q.nextKeys)

proc addOrFlushGroupwise(rq: var KUQueue;
                         grpLen: int; seen: var seq[int]; n: int;
                         noisy = true) =
  seen.add n
  if seen.len < grpLen:
    return

  # flush group-wise
  let rqLen = rq.len
  noisy.say "updateSeen: deleting ", seen.mapIt($it).join(" ")
  for a in seen:
    doAssert rq.delete(a.toKey).value.data == a.toValue
  doAssert rqLen == seen.len + rq.len
  seen.setLen(0)

proc compileGenericFunctions(rq: var KUQueue) =
  ## Verifies that functions compile, at all
  rq.del(0)
  rq[0] = 0 # so `rq[0]` works
  discard rq[0]

  let ignoreValues {.used.} = (
    (rq.append(0,0), rq.push(0,0),
     rq.replace(0,0),
     rq.prepend(0,0), rq.unshift(0,0),
     rq.shift, rq.shiftKey, rq.shiftValue,
     rq.pop, rq.popKey, rq.popValue,
     rq.delete(0)),

    (rq.hasKey(0), rq.eq(0)),

    (rq.firstKey, rq.secondKey, rq.beforeLastKey, rq.lastKey,
     rq.nextKey(0), rq.prevKey(0)),

    (rq.first, rq.second, rq.beforeLast, rq.last,
     rq.next(0), rq.prev(0)),

    (rq.firstValue, rq.secondValue, rq.beforeLastValue, rq.lastValue),

    (rq == rq, rq.len),

    (toSeq(rq.nextKeys), toSeq(rq.nextValues), toSeq(rq.nextPairs),
     toSeq(rq.prevKeys), toSeq(rq.prevValues), toSeq(rq.prevPairs)))

# ------------------------------------------------------------------------------
# Test Runners
# ------------------------------------------------------------------------------

let
  uniqueKeys = keyList.toUnique
  numUniqeKeys = keyList.toSeq.mapIt((it,false)).toTable.len
  numKeyDups = keyList.len - numUniqeKeys

suite "KeyedQueue: Data queue with keyed random access":

  block:
    var
      fwdRq, revRq: KUQueue
      fwdRej, revRej: seq[int]

    test &"All functions smoke test":
      var rq: KeyedQueue[uint,uint]
      rq.compileGenericFunctions

    test &"Append/traverse {keyList.len} items, " &
        &"rejecting {numKeyDups} duplicates":
      var
        rq: KUQueue
        rej: seq[int]
      for n in keyList:
        if not rq.push(n.toKey, n.toValue): # synonymous for append()
          rej.add n
        let check = rq.verify
        if check.isErr:
          check check.error[2] == kQOk
      check rq.len == numUniqeKeys
      check rej.len == numKeyDups
      check rq.len + rej.len == keyList.len
      fwdRq = rq
      fwdRej = rej

      check uniqueKeys == toSeq(rq.nextKeys)
      check uniqueKeys == toSeq(rq.prevKeys).reversed
      check uniqueKeys.len == numUniqeKeys

    test &"Prepend/traverse {keyList.len} items, " &
        &"rejecting {numKeyDups} duplicates":
      var
        rq: KUQueue
        rej: seq[int]
      for n in keyList:
        if not rq.unshift(n.toKey, n.toValue): # synonymous for prepend()
          rej.add n
        let check = rq.verify
        if check.isErr:
          check check.error[2] == kQOk
      check rq.len == numUniqeKeys
      check rej.len == numKeyDups
      check rq.len + rej.len == keyList.len
      check toSeq(rq.nextKeys) == toSeq(rq.prevKeys).reversed
      revRq = rq
      revRej = rej

    test "Compare previous forward/reverse queues":
      check 0 < fwdRq.len
      check 0 < revRq.len
      check toSeq(fwdRq.nextKeys) == toSeq(revRq.prevKeys)
      check toSeq(fwdRq.prevKeys) == toSeq(revRq.nextKeys)
      check fwdRej.sorted == revRej.sorted

    test "Delete corresponding entries by keyed access from previous queues":
      var seen: seq[int]
      let sub7 = keyList.len div 7
      for n in toSeq(countup(0,sub7)).concat(toSeq(countup(3*sub7,4*sub7))):
        let
          key = keyList[n].toKey
          canDeleteOk = (key.fromKey notin seen)

          eqFwdData = fwdRq.eq(key)
          eqRevData = revRq.eq(key)

        if not canDeleteOk:
          check eqFwdData.isErr
          check eqRevData.isErr
        else:
          check eqFwdData.isOk
          check eqRevData.isOk
          let
            eqFwdEq = fwdRq.eq(eqFwdData.value.fromValue.toKey)
            eqRevEq = revRq.eq(eqRevData.value.fromValue.toKey)
          check eqFwdEq.isOk
          check eqRevEq.isOk
          let
            eqFwdKey = eqFwdEq.value.fromValue.toKey
            eqRevKey = eqRevEq.value.fromValue.toKey
          check eqFwdKey == key
          check eqRevKey == key

        let
          fwdData = fwdRq.delete(key)
          fwdRqCheck = fwdRq.verify
          revData = revRq.delete(key)
          revRqCheck = revRq.verify

        if key.fromKey notin seen:
          seen.add key.fromKey

        if fwdRqCheck.isErr:
          check fwdRqCheck.error[2] == kQOk
        check fwdData.isOk == canDeleteOk
        if revRqCheck.isErr:
          check revRqCheck.error[2] == kQOk
        check revData.isOk == canDeleteOk

        if canDeleteOk:
          check fwdData.value.data == revData.value.data
      check fwdRq.len == revRq.len
      check seen.len + fwdRq.len + fwdRej.len == keyList.len

  # --------------------------------------

  block:
    const groupLen = 7
    let veryNoisy = noisy and false

    test &"Load/forward/reverse iterate {numUniqeKeys} items, "&
        &"deleting in groups of at most {groupLen}":

      # forward ...
      block:
        var
          rq = keyList.toQueue
          seen: seq[int]
          all: seq[uint]
          rc = rq.first
        while rc.isOk:
          let key = rc.value.key
          all.add key
          rc = rq.next(key)
          rq.addOrFlushGroupwise(groupLen, seen, key.fromKey, veryNoisy)
          check rq.verify.isOk
        check seen.len == rq.len
        check seen.len < groupLen
        check uniqueKeys == all

      block:
        var
          rq = keyList.toQueue
          seen: seq[int]
          all: seq[uint]
        for w in rq.nextKeys:
          all.add w
          rq.addOrFlushGroupwise(groupLen, seen, w.fromKey, veryNoisy)
          check rq.verify.isOk
        check seen.len == rq.len
        check seen.len < groupLen
        check uniqueKeys == all
      block:
        var
          rq = keyList.toQueue
          seen: seq[int]
          all: seq[uint]
        for w in rq.nextPairs:
          all.add w.key
          rq.addOrFlushGroupwise(groupLen, seen, w.key.fromKey, veryNoisy)
          check rq.verify.isOk
        check seen.len == rq.len
        check seen.len < groupLen
        check uniqueKeys == all
      block:
        var
          rq = keyList.toQueue
          seen: seq[int]
          all: seq[uint]
        for v in rq.nextValues:
          let w = v.fromValue.toKey
          all.add w
          rq.addOrFlushGroupwise(groupLen, seen, w.fromKey, veryNoisy)
          check rq.verify.isOk
        check seen.len == rq.len
        check seen.len < groupLen
        check uniqueKeys == all

      # reverse ...
      block:
        var
          rq = keyList.toQueue
          seen: seq[int]
          all: seq[uint]
          rc = rq.last
        while rc.isOk:
          let key = rc.value.key
          all.add key
          rc = rq.prev(key)
          rq.addOrFlushGroupwise(groupLen, seen, key.fromKey, veryNoisy)
          check rq.verify.isOk
        check seen.len == rq.len
        check seen.len < groupLen
        check uniqueKeys == all.reversed

      block:
        var
          rq = keyList.toQueue
          seen: seq[int]
          all: seq[uint]
        for w in rq.prevKeys:
          all.add w
          rq.addOrFlushGroupwise(groupLen, seen, w.fromKey, veryNoisy)
          check rq.verify.isOk
        check seen.len == rq.len
        check seen.len < groupLen
        check uniqueKeys == all.reversed
      block:
        var
          rq = keyList.toQueue
          seen: seq[int]
          all: seq[uint]
        for w in rq.prevPairs:
          all.add w.key
          rq.addOrFlushGroupwise(groupLen, seen, w.key.fromKey, veryNoisy)
          check rq.verify.isOk
        check seen.len == rq.len
        check seen.len < groupLen
        check uniqueKeys == all.reversed
      block:
        var
          rq = keyList.toQueue
          seen: seq[int]
          all: seq[uint]
        for v in rq.prevValues:
          let w = v.fromValue.toKey
          all.add w
          rq.addOrFlushGroupwise(groupLen, seen, w.fromKey, veryNoisy)
          check rq.verify.isOk
        check seen.len == rq.len
        check seen.len < groupLen
        check uniqueKeys == all.reversed

    test &"Load/forward/reverse steps {numUniqeKeys} key/item consistency":

      # forward ...
      block:
        var
          rq = keyList.toQueue
          count = 0
          rc = rq.firstKey
        while rc.isOk:
          check uniqueKeys[count] == rc.value
          rc = rq.nextKey(rc.value)
          count.inc
        check rq.verify.isOk
        check count == uniqueKeys.len
      block:
        var
          rq = keyList.toQueue
          count = 0
          rc = rq.first
        while rc.isOk:
          check uniqueKeys[count] == rc.value.data.fromValue.toKey
          rc = rq.next(rc.value.key)
          count.inc
        check rq.verify.isOk
        check count == uniqueKeys.len

      # reverse ...
      block:
        var
          rq = keyList.toQueue
          count = uniqueKeys.len
          rc = rq.lastKey
        while rc.isOk:
          count.dec
          check uniqueKeys[count] == rc.value
          rc = rq.prevKey(rc.value)
        check rq.verify.isOk
        check count == 0
      block:
        var
          rq = keyList.toQueue
          count = uniqueKeys.len
          rc = rq.last
        while rc.isOk:
          count.dec
          check uniqueKeys[count] == rc.value.data.fromValue.toKey
          rc = rq.prev(rc.value.key)
        check rq.verify.isOk
        check count == 0

  # --------------------------------------

  test &"Load/delete 2nd entries from either queue end until only one left":
    block:
      var rq = keyList.toQueue
      while true:
        let rc = rq.secondKey
        if rc.isErr:
          check rq.second.isErr
          break
        let key = rc.value
        check rq.second.value.data == rq[key]
        check rq.delete(key).isOk
        check rq.verify.isOk
      check rq.len == 1

    block:
      var rq = keyList.toQueue
      while true:
        let rc = rq.beforeLastKey
        if rc.isErr:
          check rq.beforeLast.isErr
          break
        let key = rc.value
        check rq.beforeLast.value.data == rq[key]
        check rq.delete(key).isOk
        check rq.verify.isOk
      check rq.len == 1

  # --------------------------------------

  test &"Deep copy semantics":
    var
      rp = keyList.toQueue
      rq = rp
    let
      reduceLen = (rp.len div 3)
    check 0 < reduceLen
    check rp == rq
    for _ in 1 .. (rp.len div 3):
      let key = rp.firstKey.value
      check rp.delete(key).value.data.fromValue.toKey == key
    check rq.len == numUniqeKeys
    check rp.len + reduceLen == rq.len


suite "KeyedQueue: Data queue as LRU cache":

  test "Fill Up":
    var
      cache = newSeq[int]().toLruCache
      cExpected = keyList.toLruCache
    for w in keyList:
      var
        item = (w mod lruCacheModulo)
        reSched = cache.q.hasKey(item.toKey)
        value = cache.lruValue(item)
        queue = toSeq(cache.q.nextPairs).mapIt(it.key)
        values = toSeq(cache.q.nextPairs).mapIt(it.data)
        infoPfx = if reSched: ">>> rotate" else: "+++ append"
      noisy.say infoPfx, &"{value} => {queue}"
      check cache.q.verify.isOk
      check queue.mapIt($it) == values.mapIt($it.fromValue)
      check item.toKey == cache.q.lastKey.value
    check toSeq(cache.q.nextPairs) == toSeq(cExpected.q.nextPairs)

  test "Deep copy semantics":
    var
      c1 = keyList.toLruCache
      c2 = c1

    check c1 == c2
    check c1.lruValue(77) == 77.toValue

    check c1.q.verify.isOk
    check c2.q.verify.isOk

    noisy.say &"c1Specs: {c1.size} {c1.q.firstKey} {c1.q.lastKey} ..."
    noisy.say &"c2Specs: {c2.size} {c2.q.firstKey} {c2.q.lastKey} ..."

    check c1 != c2
    check toSeq(c1.q.nextPairs) != toSeq(c2.q.nextPairs)

  # --------------------

  test "Random Access Delete":
    var
      c1 =  keyList.toLruCache
      sq = toSeq(c1.q.nextPairs).mapIt(it.key.fromKey)
      s0 = sq
      key = sq[5].toKey

    when (NimMajor, NimMinor) >= (1, 6):
      sq.delete(5..5) # delete index 5 in sequence
    else:
      sq.delete(5, 5) # delete index 5 in sequence

    noisy.say &"sq: {s0} <off sq[5]({key})> {sq}"

    check c1.q.delete(key).value.key == key
    check sq == toSeq(c1.q.nextPairs).mapIt(it.key.fromKey)
    check c1.q.verify.isOk

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