Implement a Markov chain hook

rowbot

@@ -115,7 +115,7 @@ prog_args=( "$@" )
 server=irc.libera.chat port=6667 tls=no client_cert=
 nick=rowbot-dev ident=rowbot realname=rowbot chan=
 trigger=\` fact_root=. reload=no level=info log_fd=1 log=
-sys_root=sysfacts owner=${USER:-uplime} dev=no
+sys_root=sysfacts owner=${USER:-uplime} dev=no markov_seed=
 
 ###
 # apply custom config
@@ -185,6 +185,25 @@ fi
 # apply reloaded values
 ###
 
+if [[ $markov_seed ]]; then
+  if [[ -f $markov_seed ]]; then
+    declare -A markov_chains enabled
+    read -ra words < "$markov_seed"
+
+    for (( idx = 0; idx < ${#words[@]} - 2; idx++ )); do
+      key="${words[$idx]} ${words[$idx + 1]}"
+
+      if [[ -z ${markov_chains[$key]} ]]; then
+        markov_chains[$key]=${words[$idx + 2]}
+      else
+        markov_chains[$key]+=" ${words[$idx + 2]}"
+      fi
+    done
+  else
+    die "seed file does not exist: %s" "$markov_seed"
+  fi
+fi
+
 if [[ $reload = yes ]]; then
   reload_vars=(
     nick ident host level log log_fd alarm_pid tls_pid in_sock
@@ -656,6 +675,65 @@ hook_pre_PRIVMSG_CTCP() {
   return 1
 }
 
+hook_post_PRIVMSG_markov() {
+  if [[ ! ${markov_chains@A} ]]; then
+    return 0
+  elif [[ ${to:0:1} = \# && ${enabled[$to]} != yes ]]; then
+    return 0
+  elif (( ${#action_args[@]} < 3 )); then
+    return 0
+  fi
+
+  local idx key
+
+  for (( idx = 0; idx < ${#action_args[@]} - 2; idx++ )); do
+    key="${action_args[$idx]} ${action_args[$idx + 1]}"
+
+    if [[ -z ${markov_chains[$key]} ]]; then
+      markov_chains[$key]=${words[$idx + 2]}
+    else
+      markov_chains[$key]+=" ${words[$idx + 2]}"
+    fi
+  done
+}
+
+hook_cmd_markov() {
+  local keys idx key str chains next vals val_idx
+
+  if [[ ! ${markov_chains@A} ]]; then
+    if [[ $action = markov ]]; then
+      privmsg "$to" "markov chains are not enabled"
+    fi
+
+    return 0
+  fi
+
+  case $action in
+  enable)
+    enabled[$to]=yes
+    privmsg "$to" "now recording $to"
+    ;;
+  disable)
+    enabled[$to]=no
+    privmsg "$to" "no longer recording $to"
+    ;;
+  markov)
+    keys=("${!markov_chains[@]}")
+    (( idx = RANDOM % ${#keys[@]} ))
+    key=${keys[$idx]} str=$key
+    chains=0
+
+    while [[ -v markov_chains[$key] ]] && (( chains++ < 100 )); do
+      read -ra vals <<< "${markov_chains[$key]}"
+      (( val_idx = RANDOM % ${#vals[@]} ))
+      next="$key ${vals[$val_idx]}" next=${next#* }
+      str+=" ${next#* }" key=$next
+    done
+
+    privmsg "$to" "$from: $str"
+  esac
+}
+
 hook_cmd_factoids() {
   local key val facts msg