#!/bin/bash

DEBUG=:
#DEBUG=echo

#INDENT_SPACE_SHORT=2
#INDENT_SPACE=4
#INDENT_TAB=2
#rex_nonemptyline_indent='^([ ]{'$INDENT_SPACE_SHORT'}|[ ]{'$INDENT_SPACE'}|[\	]{'$INDENT_TAB'})[[:graph:]]+' # for $INDENT_SPACE spaces or $INDENT_TAB tabs

rex_emptyline='^$'
rex_nonemptyline='^([[:blank:]]*)([[:graph:]]+.*)'
rex_header='^[[:blank:]]*(#+)[[:blank:]]*(.*)'
rex_list_start='^([[:blank:]]{0,1})([*+-]{1} +|[[:digit:]]+\.)(.*)'; flag_list=0; indent_list=
rex_list_level='^([[:blank:]]{2,})([*+-]{1} +|[[:digit:]]+\.)(.*)'
rex_list="$rex_list_start"
rex_codeblock='^[[:blank:]]*(```)(.*)'
rex_codeinline_start='([^`]*)(`{1,2})(.*)'
rex_codeinline_space='(^[[:blank:]]{4})([[:blank:]]*)(.*)'
rex_codeinline1='([^`]*)(`)(.*)'
rex_codeinline2='(``)(.*)$' # first part of $line: ${line%"${BASH_REMATCH[0]}"}
rex_codeinline="$rex_codeinline_start"
rex_quote='^([[:blank:]]*>)(.*)'; flag_quote=0
rex_emphasis_start='([^*_]*)([*_]{1,2})([^ ].*)'
rex_emphasis_end='([^*_]*)([*_]{1,2})(.*)'
rex_emphasis="$rex_emphasis_start"
rex_link='([^[]*\[+)([^]]*)(\]+ *[\([])([^]\)]*)([]\)].*)'
rex_autolink='([^<]*<)([^>]*)(>)(.*)'

TEXT_INDENT=0
LIST_INDENT_LAST=
LINE_INDENT=
LINE_INDENT_N=
LINE_EMPTY_N=

PARSE_STATE=0
PARSE_FIX=0
FIX_STATE=0
UNFIX_STATE=0

# Next parsted line is directed directly to the fixed state
fix() {
  PARSE_FIX=1
  FIX_STATE=$PARSE_STATE
  [ ! -z "$1" ] && PARSE_STATE=$1
}
isfix() { [ $PARSE_FIX -ne 0 ] && [ $FIX_STATE -eq $PARSE_STATE ]; return $?; }
# Unfix and/or stop parsing for this line
unfix() {
  UNFIX_STATE=1
  PARSE_FIX=0
  FIX_STATE=0
}
isunfix() { [ $UNFIX_STATE -ne 0 ]; return $?; }
# Decides when to got the next parser stop
# Called usually like: fall || break
fall() {
  if isunfix; then
    $DEBUG -n "U]"
    UNFIX_STATE=0
    PARSE_STATE=0
    return 1
  fi
  # Fall to next PARSE_STATE if not fixed
  if [ $PARSE_FIX -eq 0 ]; then
    ((PARSE_STATE++))
    return 0
  fi
  if [ $PARSE_STATE -ne $FIX_STATE ]; then
    PARSE_STATE=$FIX_STATE
    return 0
  else
    $DEBUG -n "B]"
    return 1
  fi
}

parseline() {
  local line="$1"
  local tocheck="$1"
  local format_prefix=
  local format_suffix=

  [ $PARSE_FIX -eq 0 ] && PARSE_STATE=0

  while : ; do
    $DEBUG -n "$PARSE_STATE]"
    case "$PARSE_STATE" in
      0) ## Empty line ##
        if [[ "$tocheck" =~ $rex_emptyline ]]; then
          ((LINE_EMPTY_N++))
          # End quote
          [ $flag_quote -ne 0 ] && flag_quote=0 && unfix

          # End text indent
          [ $TEXT_INDENT -ne 0 ] && TEXT_INDENT=0
          
          # TODO? Catch rouge formates with empty lines outside codeblocks
          echo -ne "$FO_RESET"
          format_prefix=""
          format_suffix=""
        fi
        fall || break;;
      1) ## Non empty line ##
        if [[ "$tocheck" =~ $rex_nonemptyline ]]; then
          LINE_INDENT_N=${#BASH_REMATCH[1]}
          LINE_INDENT="${BASH_REMATCH[1]}"
          LINE_EMPTY_N=0
          # List ending
          if [ $flag_list -ne 0 ] && [ $LINE_INDENT_N -le 1 ] && [ $TEXT_INDENT -eq 0 ]; then
            rex_list="$rex_list_start"
            flag_list=0
            indent_list=
            LIST_INDENT_LAST=
          fi
        fi
        fall || break;;
      2) ## List ##
        if [[ "$tocheck" =~ $rex_list ]]; then

          indent_list[$flag_list]="$LINE_INDENT"
          LIST_INDENT_LAST="$LINE_INDENT"
          if (($flag_list  > 0 )); then 
            local level=$((${#LINE_INDENT} - ${#indent_list[$flag_list - 1]}))
            #echo -n $level
            #if (($level > 1 )); then
            #  echo -n ">]"
            #elif (($level < -1 )); then
            #  echo -n "<]"
            #else
            #  echo -n "=]"
            #fi
          fi
          # Detect indent TODO detect levels of indent
          #local tab=$(printf '\t')
          #case "$LINE_INDENT" in
          #  "${tab}${tab}")
          #    LINE_INDENT="${BASH_REMATCH[1]}"
          #    $DEBUG -n "2t]";;
          #  '    ')
          #    LINE_INDENT="${BASH_REMATCH[1]}"
          #    $DEBUG -n "4s]";;
          #  '  ')
          #    LINE_INDENT="${BASH_REMATCH[1]}"
          #    $DEBUG -n "2s]";;
          #  *)
          #    LINE_INDENT=
          #esac


          ((flag_list++))

          rex_list="$rex_list_level"
          local indent=
          [ $flag_list -gt 1 ] && indent="$LINE_INDENT" #"${BASH_REMATCH[1]}"
          printf "%s%b%s%b" "$indent" "$FO_LISTITEM" "${BASH_REMATCH[2]}" "$FO_RESET"
          tocheck="${BASH_REMATCH[3]}"
          line="$tocheck"
        elif [[ "$tocheck" =~ $rex_list_start ]]; then
          # Start of new list
          flag_list=0
          indent_list=
          LIST_INDENT_LAST=
          rex_list="$rex_list_start"
          continue
        elif [ $flag_list -ne 0 ] && [ $LINE_INDENT_N -le 1 ] && [ $TEXT_INDENT -ne 0 ]; then
          printf "%-${TEXT_INDENT}s" " "
        fi
        fall || break
        ;;
      3) ## Header ##
        if [[ "$tocheck" =~ $rex_header ]]; then
          format_prefix="${FO_HEADLINE}"
          format_suffix="${FO_RESET}"
          unfix
        fi
        fall || break;;
      4) ## Quotes
        if [[ "$tocheck" =~ $rex_quote ]] || isfix; then
          # TODO continue parsing quoted string
          fix 0
          flag_quote=1
          format_prefix="${FO_QUOTE}"
          format_suffix="${FO_RESET}"
          break
        else
          fall || break
        fi
        ;;
      5) ## Multiline code blocks ##
        if [[ "$tocheck" =~ $rex_codeblock ]]; then
          if isfix; then
            format_suffix="${FO_RESET}"
            unfix
          else
            format_prefix="${FO_CODEBLOCK}"
            fix
          fi
        fi
        fall || break;;
      6) ## Code block started with spaces
        if [[ "$tocheck" =~ $rex_codeinline_space ]]; then
          if [ $LINE_INDENT_N -eq 4 ] && [ $flag_list -ne 0 ]; then
            # First line of text paragraph inside a list item
            # signaling indentation for the following lines
            TEXT_INDENT=$LINE_INDENT_N
          else
            # Code block started with 4 spaces TODO 2 tabs
            if [ $flag_list -ne 0 ] && [ $LINE_INDENT_N -ge 8 ]; then
              # Indent code line according to list level
              printf "%-4s%s" " " "$LIST_INDENT_LAST"
              # Remove 4 leading spaces
              printf "%b%s" "$FO_CODEBLOCK" "${BASH_REMATCH[2]#'    '}"
            else
              # Print code related spaces
              printf "%b%s" "$FO_CODEBLOCK" "${BASH_REMATCH[2]}"
            fi
            
            format_suffix="$FO_RESET"
            printf "%b%s" "$FO_CODEBLOCK" "${BASH_REMATCH[3]}"
            line=
            unfix
          fi
        fi
        fall || break;;
      7) ## Inline code blocks ##
        if [[ "$tocheck" =~ $rex_codeinline ]]; then
          if isfix; then
            local lazym="${tocheck%"${BASH_REMATCH[0]}"}"
            if [ -z "$lazym" ]; then
              printf "%b%s%b" "$FO_CODEBLOCK" "${BASH_REMATCH[1]}${BASH_REMATCH[2]}" "${FO_RESET}"
              tocheck="${BASH_REMATCH[3]}"
            else
              printf "%b%s%b" "$FO_CODEBLOCK" "${lazym}${BASH_REMATCH[1]}" "${FO_RESET}"
              tocheck="${BASH_REMATCH[2]}"
            fi
            rex_codeinline="$rex_codeinline_start"
            unfix
          else
            if [ '``' == "${BASH_REMATCH[2]}" ]; then
              rex_codeinline="$rex_codeinline2"
            else
              rex_codeinline="$rex_codeinline1"
            fi
            printf "%s%b%s" "${BASH_REMATCH[1]}" "${FO_CODEBLOCK}" "${BASH_REMATCH[2]}"
            tocheck="${BASH_REMATCH[3]}"
            fix
          fi
          line="$tocheck"
        elif isfix; then
          # Open inline block at end of line
          format_suffix="$FO_RESET"
          fall || break
        fi
        fall;;
      8) ## Inline emphasis start
        if [[ "$tocheck" =~ $rex_emphasis ]]; then
          local fo_emphasis=$FO_EMPHASIS1
          if isfix; then
            printf "%s%b" "${BASH_REMATCH[1]}${BASH_REMATCH[2]}" "${FO_RESET}"
            rex_emphasis="$rex_emphasis_start"
            unfix
          else
            if [ '**' == "${BASH_REMATCH[2]}" ] || [ '__' == "${BASH_REMATCH[2]}" ]; then
              fo_emphasis=$FO_EMPHASIS2
            fi
            printf "%s%b%s" "${BASH_REMATCH[1]}" "${fo_emphasis}" "${BASH_REMATCH[2]}"
            rex_emphasis="$rex_emphasis_end"
            fix
          fi
          tocheck="${BASH_REMATCH[3]}"
          line="$tocheck"
        elif isfix; then
          # Open inline block at end of line
          fall || break
        fi
        fall;;
      9) ## Links within one line ##
        if [[ "$tocheck" =~ $rex_link ]]; then
          printf "%s%b%s%b%s%b%s%b%s" "${BASH_REMATCH[1]}" "${FO_LINKTEXT}" "${BASH_REMATCH[2]}" "${FO_RESET}" "${BASH_REMATCH[3]}" "${FO_LINKURL}" \
            "${BASH_REMATCH[4]}" "${FO_RESET}"
          tocheck="${BASH_REMATCH[5]}"
          line="$tocheck"
          [ ! -z "$tocheck" ] && fix
        elif isfix; then
          unfix
          fall || break
        fi
        fall;;
      10) ## Auto-links within one line ##
        if [[ "$tocheck" =~ $rex_autolink ]]; then
          printf "%s%b%s%b%s" "${BASH_REMATCH[1]}" "${FO_LINKURL}" "${BASH_REMATCH[2]}" "${FO_RESET}" "${BASH_REMATCH[3]}"
          tocheck="${BASH_REMATCH[4]}"
          line="$tocheck"
          [ ! -z "$tocheck" ] && fix
        elif isfix; then
          unfix
          fall || break
        fi
        fall;;
      *) ## Regular text
        $DEBUG -n "e]$tocheck"
        break;;
    esac
  done

  printf "%b%s%b" "$format_prefix" "$line" "$format_suffix"
  printf "\n"
}

catmd() {
  for arg in "$@"; do
    case "$1" in 
      -)
        # treat - as input stream
        break;;
      -*)
        # Ignore args for now
        shift;;
    esac
  done
 
  local line=
  local myargs=("$@")

  # Use standard input if now files are present
  [ $# -eq 0 ] && myargs[0]="/dev/stdin"
  
  for file in "${myargs[@]}"; do
    [ "$file" == "-" ] && file="/dev/stdin"
    while IFS='' read -r line; do 
      parseline "$line"
    done <"${file}"
    # If last line in a file has no newline, read ends but still populates $line
    [[ $line ]] && parseline "$line"
    echo -en "$FO_RESET"
  done
}

## Font formating
FO_RESET=$(tput sgr0)
FO_BLINK=$(tput blink) # '\033[5m'
FO_BOLD=$(tput bold) # '\033[1m'
FO_SO=$(tput smso) # '\033[7m'
FO_SO_E=$(tput rmso) # '\033[27m'
FO_UL=$(tput smul) # '\033[4m'
FO_UL_E=$(tput smul) # '\033[24m'
FO_INVIS=$(tput invis) # '\033[8m'
## Rareley supported
FO_DIM=$(tput dim)
FO_REV=$(tput rev)

## Colorcodes
## 
##  '\033[Xm'      - Basic 8 colors
##                   X = 30..37 foreground
##                     = 40..47 background
##                     = Black, Red, Green, Yellow, Blue, Magenta, Cyan, Light gray
##                     = 39 = default foreground
##                     = 49 = default background
##                 - Basic "high contrast" colors
##                   X =  90...97 foreground
##                     = 100..107 background
##                     = Dark grey, Light red, green, yellow, blue, magenta, cyan, white
##                 - Format
##                   X: 0 = reset, 1 = bold, 2 = dim,
##                      4 = underline, 5 = slow blink,
##                      7 = Reverse, 8 = hidden
##                   20+X: Reset of formating
##                         e.g. 21 = reset bold
##  '\033[38;5;Xm' - xterm-256 foreground colors  X = 0..255
##  '\033[48;5;Xm' - xterm-256 foreground colors  X = 0..255
COB_BLACK='\033[40m'
COB_LIGHTGRAY='\033[100m'
COF_BLACK='\033[0;30m' 
COF_DARKGRAY='\033[1;30m'
COF_RED='\033[0;31m'
COF_LIGHTRED='\033[1;31m'
COF_GREEN='\033[0;32m'
COF_LIGHTGREEN='\033[1;32m'
COF_ORANGE='\033[0;33m'
COF_YELLOW='\033[1;33m'
COF_BLUE='\033[0;34m'
COF_LIGHTBLUE='\033[1;34m'
COF_PURPLE='\033[0;35m'
COF_LIGHTPURPLE='\033[1;35m'
COF_CYAN='\033[0;36m'
COF_LIGHTCYAN='\033[1;36m'
COF_LIGHTGRAY='\033[0;37m'
COF_WHITE='\033[1;37m'

FO_HEADLINE="$FO_BOLD$FO_SO"
FO_LISTITEM="$COF_ORANGE"
FO_EMPHASIS1="${COF_LIGHTGRAY}"
FO_EMPHASIS2="${COF_WHITE}"
FO_LINKTEXT="${COF_LIGHTGRAY}"
FO_LINKURL="${FO_UL}"
FO_CODEBLOCK="$COF_LIGHTGRAY$COB_LIGHTGRAY"
FO_QUOTE='\033[96;100m'

catmd "$@"