# no-nonsense FreeCell in POSIX AWK
# run as: [n]awk -f nnfc.awk [-v ASCII=1] [-v MONOCHROME=1] [-v SEED=x]
# commands: q - quit, u - undo, ah - autohome, h - help,
# [number][number] - move from column/freecell to column/freecell/foundation:
# - 0 is foundation (can be omitted)
# - 1 to 8 are column numbers
# - a, b, c, d are freecell numbers
# SEED variable can be used to init games M$-style
# no supermove support for now, need to move cards one at a time
# created by Luxferre in 2024, released into public domain

# Helper functions

function alen(a, i, k) { # determine array length
  k = 0
  for(i in a) k++
  return k
}

# split a string with separator into an array but with 0-based indexes
function asplit(s, a, sep, len, i) {
  split(s, a, sep) # get 1-based-index array in a
  len = alen(a)
  for(i=0;i<len;i++) a[i] = a[i+1] # move everything to the left
  delete a[len] # delete the last element after moving
}

# serialize any associative array into a string
# sep must be a single char not occurring in any key or value
function assocser(aa, sep, outs, k) {
  outs = "" # initialize an ordered array string
  for(k in aa) # iterate over keys
    outs = outs sep k sep aa[k]
  return substr(outs, 2) # delete the first sep
}

# deserialize any associative array from a string
# sep must be a single char used when calling assocser() function
function assocdes(s, aa, sep, oa, i, len) {
  split("", aa) # erase aa array
  split(s, oa, sep) # get 1-based ordered array in oa
  len = alen(oa) # ordered array length
  for(i=1;i<=len;i+=2) # populate aa
    aa[oa[i]] = oa[i+1]
}


# get card suit index (0=clubs, 1=diamonds, 2=hearts, 3=spades)
function getsuit(n) {return int(n/13)}

# get card color by numeric value: 0 is red, 1 is black
function getcolor(n, si) {si = getsuit(n); return (si > 0 && si < 3) ? 0 : 1}

# Traditional M$ FreeCell LCG for deal emulation
function fclcg() {
  fc_lstate = (214013 * fc_lstate + 2531011) % 2147483648
  return int(fc_lstate / 65536)
}

# render the playfield from cardstr, table, fcell and fnd arrays
function render(i, j, res) {
  res = ""
  # top left: free cells
  for(i=0;i<4;i++) res = res sprintf("%s", cardstr[fcell[i]])
  # top right: foundations
  for(i=0;i<4;i++) res = res sprintf("%s", cardstr[fnd[i]])
  res = res "\n"
  # delimiter
  for(i=0;i<23;i++) res = res "-"
  res = res "\n"
  # main table rendering 
  # max possible column length is 20 elements (8 + 12)
  for(j=0;j<20;j++) {
    for(i=0;i<8;i++) {
      if((i,j) in table)
        res = res cardstr[table[i,j]]
      else res = res "   "
    }
    res = res "\n"
  } 
  sub(/[ \t\n\r]+$/, "", res) # trim all trailing whitespace
  printf("\nGame #%u\n", fc_deal)
  print res # finally print out the resulting field
}

# main logic/move function (also handles the undo)
# statuses: 0 - invalid move, 1 - continue, 2 - victory
function domove(cmd, valid, nums, from, to, si) {
  if(cmd == "u") { # undo logic
    if(undoidx > 0) {
      undoidx--
      assocdes(undos["table",undoidx], table, ",")
      assocdes(undos["fnd",undoidx], fnd, ",")
      assocdes(undos["fcell",undoidx], fcell, ",")
      assocdes(undos["tablens",undoidx], tablens, ",")
    } else print "Nowhere to undo!"
    return 1 # continue
  }
  valid = 0 # invalid by default until all checks are done
  # if cmd is not q, h, ah or u, then it must be two numbers
  split(cmd, nums, "") # numbers must be space-separated
  from = nums[1] # location from which we're moving
  to = nums[2] # location to which we're moving
  # identify free cells
  if(from == "a") from = 9
  if(from == "b") from = 10
  if(from == "c") from = 11
  if(from == "d") from = 12
  if(to == "a") to = 9
  if(to == "b") to = 10
  if(to == "c") to = 11
  if(to == "d") to = 12
  from = int(from)
  to = int(to)
  rfrom = from - 1 # real from location
  rto = to - 1 # real to location
  if(from > 0 && from < 13 && to > -1 && to < 13) { # first check
    # determine what card we're trying to move
    cval = -1
    if(from < 9) { moving from a non-empty tableau
      if(tablens[rfrom] > 0 && length(table[rfrom,tablens[rfrom]-1]) > 0)
        cval = int(table[rfrom,tablens[rfrom]-1])
    } else cval = fcell[from - 9]
    if(cval > -1) { # we are moving a non-empty value
      if(to == 0) { # moving to a foundation
        si = getsuit(cval) # get suit index
        if((fnd[si]%13) == ((cval%13) - 1)) { # we can move there
          fnd[si] = cval 
          if(from < 9) { # moving from a tableau
            delete table[rfrom,tablens[rfrom]-1] # delete the card
            tablens[rfrom]-- # decrease tableau length
          } else fcell[from - 9] = -1 # moving from a free cell 
          valid = 1 # mark the move as valid
        }
      } else if(to < 9) { # moving to a tableau
        si = table[rto,tablens[rto]-1] # target value
        if((getcolor(cval) != getcolor(si) && (cval%13) == (si%13) - 1) || si == "") {
          table[rto,tablens[rto]] = cval # copy the card there
          tablens[rto]++ # increase tableau length
          if(from < 9) { # moving from a tableau
            delete table[rfrom,tablens[rfrom]-1] # delete the card
            tablens[rfrom]-- # decrease tableau length
          } else fcell[from - 9] = -1 # moving from a free cell 
          valid = 1 # mark the move as valid
        }
      } else if(fcell[to - 9] == -1) { # moving to a free cell
        fcell[to - 9] = cval
        if(from < 9) { # moving from a tableau
          delete table[rfrom,tablens[rfrom]-1] # delete the card
          tablens[rfrom]-- # decrease tableau length
        } else fcell[rfrom - 9] = -1 # moving from a free cell
        valid = 1 # mark the move as valid
      }
    }
  }
  if(valid == 1) { # the move is valid and performed
    undoidx++ # increment the undo index
    # save the new playfield data under it
    undos["table",undoidx] = assocser(table, ",")
    undos["fnd",undoidx] = assocser(fnd, ",")
    undos["fcell",undoidx] = assocser(fcell, ",")
    undos["tablens",undoidx] = assocser(tablens, ",")
  }
  # now, check for the win condition: all kings in fnd
  if(fnd[0] == 12 && fnd[1] == 25 && fnd[2] == 38 && fnd[3] == 51) return 2
  else return valid # we can use the external move status
}

# automatically move all eligible cards to the foundation
function autohome(chres, lres, i) {
  do {
    chres = 0
    for(i=1;i<9;i++) {
      lres = domove(i "0")
      if(lres == 2) return 2
      else chres += lres
    }
    lres = domove("a0")
    if(lres == 2) return 2
    else chres += lres
    lres = domove("b0")
    if(lres == 2) return 2
    else chres += lres
    lres = domove("c0")
    if(lres == 2) return 2
    else chres += lres
    lres = domove("d0")
    if(lres == 2) return 2
    else chres += lres
  } while(chres > 0)
  return 1 # always continue
}

function help() {
  return 1 # continue
}

BEGIN { # main code part
  if(SEED) fc_lstate = SEED; else { # initialize PRNG
    srand();
    fc_lstate = int(rand() * 2146483648)
  }
  fc_deal = fc_lstate # save the deal number
  asplit("A 2 3 4 5 6 7 8 9 T J Q K", cvals, " ") # card values
  suits[0] = ASCII ? "c" : "\xe2\x99\xa3" # clubs
  suits[1] = ASCII ? "d" : "\xe2\x99\xa6" # diamonds
  suits[2] = ASCII ? "h" : "\xe2\x99\xa5" # hearts
  suits[3] = ASCII ? "s" : "\xe2\x99\xa0" # spades
  cstart[0] = MONOCHROME ? "" : "\x1b[31m" # red
  cstart[1] = MONOCHROME ? "" : "\x1b[37m" # black (white)
  cend = MONOCHROME ? "" : "\x1b[39m" # reset color
  split("", usedinds) # init used indices cache
  split("", cardstr) # init card strings array (exactly 3 char long each)
  for(i=0;i<52;i++) { # populate it
    si = getsuit(i) # suit index
    cardstr[i] = cstart[getcolor(i)] sprintf("%s", cvals[i%13]) suits[si] cend " "
  }
  cardstr[-1] = "__ " # empty position denoted by -1 index
  split("", seqarr) # init sequential array
  for(i=0;i<52;i+=4) { # populate it
    seqarr[i] = int(i/4)
    seqarr[i+1] = seqarr[i]+13
    seqarr[i+2] = seqarr[i]+26
    seqarr[i+3] = seqarr[i]+39
  }
  rowidx = 0 # deal row index
  colidx = 0 # deal column index
  split("", table) # init tableau array
  while((slen = alen(seqarr)) > 0) { # populate it
    idx = fclcg() % slen   # get the index to select
    table[colidx++, rowidx] = seqarr[idx] # get the selected card value
    seqarr[idx] = seqarr[slen - 1] # copy the last card to the index
    delete seqarr[slen - 1] # shrink the array
    if(colidx > 7) {rowidx++; colidx=0} # wrap around the deal columns
  }
  # init freecells and foundations arrays
  fcell[0] = fnd[0] = -1
  fcell[1] = fnd[1] = -1
  fcell[2] = fnd[2] = -1
  fcell[3] = fnd[3] = -1
  # init tableu length tracker array
  asplit("7 7 7 7 6 6 6 6", tablens, " ")
  # init undo array and index
  undos["table",0] = assocser(table, ",")
  undos["fnd",0] = assocser(fnd, ",")
  undos["fcell",0] = assocser(fcell, ",")
  undos["tablens",0] = assocser(tablens, ",")
  undoidx = 0 # the current undo index is 0
  # first-time display
  print "nnfc by Luxferre\nenter h for command help"
  render()
  printf("\n> ")
  while((getline cmd) > 0) { # main interactive loop
    cmd = tolower(cmd) # accept both uppercase and lowercase
    if(cmd == "q") {print "Quitting..."; break}
    else if(cmd == "h")  res = help()
    else if(cmd == "ah") res = autohome()
    else { # pass the command to the logic function
      res = domove(cmd) 
      if(res == 0) print "Invalid move!"
    }
    render()
    if(res == 2) {print "Victory!"; break}
    printf("\n> ")
  }
}