#!/bin/bash

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# Colorize some string based on its hash
# 2025: Mostly written by chatgpt, 
# but with a lot of brontosaurusrex input and corrections

# -------------------------------------------------------
# usage: 
# sinesthesia "woot woot woot"
# cat some.txt | sinesthesia
# sinesthesia --theme=ocean "woot woot woot"
# (autumn, ocean, forest, glacier, herbal, icefire, tealgray, sunset)
# zsh:
# repeat 9 sinesthesia
# -------------------------------------------------------

# Global color controls
sat="25" # Some themes may override it
light="93"
theme=""

# Avoid certain hues
avoidPink="0"
avoidYellow="0"
debug="0"

# --- Helpers ---

hsv_to_rgb() {
  awk -v h="$1" -v s="$2" -v v="$3" '
  BEGIN {
    h = (h % 360 + 360) % 360
    s /= 100
    v /= 100
    c = v * s
    h_ = h / 60
    x = c * (1 - ((h_ % 2) - 1)^2)
    m = v - c

    if (h_ < 1)      { r = c; g = x; b = 0 }
    else if (h_ < 2) { r = x; g = c; b = 0 }
    else if (h_ < 3) { r = 0; g = c; b = x }
    else if (h_ < 4) { r = 0; g = x; b = c }
    else if (h_ < 5) { r = x; g = 0; b = c }
    else             { r = c; g = 0; b = x }

    r = int((r + m) * 255 + 0.5)
    g = int((g + m) * 255 + 0.5)
    b = int((b + m) * 255 + 0.5)

    printf "%d %d %d\n", r, g, b
  }'
}

gamma_correct() {
  awk -v targetY="$1" '
  function to_linear(v) {
    v = v / 255
    return (v <= 0.04045) ? v / 12.92 : ((v + 0.055) / 1.055)^2.4
  }
  function to_srgb(v) {
    return (v <= 0.0031308) ? v * 12.92 : 1.055 * (v ^ (1/2.4)) - 0.055
  }
  {
    r = to_linear($1)
    g = to_linear($2)
    b = to_linear($3)
    Y = 0.2126 * r + 0.7152 * g + 0.0722 * b

    if (Y > 0) {
      scale = targetY / Y
      r *= scale; g *= scale; b *= scale
    }

    r = int(to_srgb(r) * 255 + 0.5)
    g = int(to_srgb(g) * 255 + 0.5)
    b = int(to_srgb(b) * 255 + 0.5)

    printf "%d %d %d\n", (r > 255 ? 255 : (r < 0 ? 0 : r)), (g > 255 ? 255 : (g < 0 ? 0 : g)), (b > 255 ? 255 : (b < 0 ? 0 : b))
  }'
}

# --- Theme remapping ---

remap_hue() {
  local hue="$1"
  local new_hue="$hue"
  local new_sat="$sat"

  case "$theme" in
    autumn)
      new_hue=$(( (hue % 50) + 20 )) ;;
    ocean)
      new_hue=$(( (hue % 100) + 140 )) ;;
    forest)
      new_hue=$(( (hue % 60) + 90 )) ;;
    glacier)
      new_hue=$(( (hue % 50) + 170 )) ;;
    herbal)
      new_hue=$(( (hue % 60) + 120 )) ;;
    icefire)
      case $((hue % 4)) in
        0) new_hue=20 ;;
        1) new_hue=200 ;;
        2) new_hue=40 ;;
        3) new_hue=260 ;;
      esac ;;
    tealgray)
      case $((hue % 4)) in
        0) new_hue=176; new_sat=57 ;;  # #66D2CE
        1) new_hue=172; new_sat=58 ;;  # #2DAA9E
        2) new_hue=0;   new_sat=0  ;;  # #EAEAEA
        3) new_hue=30;  new_sat=17 ;;  # #E3D2C3
      esac ;;
    sunset)
      case $((hue % 7)) in
        0) new_hue=163; new_sat=42 ;;  # #84E3C8
        1) new_hue=158; new_sat=27 ;;  # #A8E6CF
        2) new_hue=83;  new_sat=19 ;;  # #DCEDC1
        3) new_hue=24;  new_sat=29 ;;  # #FFD3B6
        4) new_hue=3;   new_sat=35 ;;  # #FFAAA5
        5) new_hue=355; new_sat=45 ;;  # #FF8B94
        6) new_hue=355; new_sat=55 ;;  # #FF7480
      esac
      ;;
  esac

  echo "$new_hue $new_sat"
}

# --- Core function ---

colorize_string() {
  local string="$1"

  # fallback string
  if [ -z "$string" ]; then
    string="███████████████████████
███████████████████████ $RANDOM$$
███████████████████████"
  fi

  local hash hue red grn blu
  hash="$(echo "$string" | cksum | cut -d ' ' -f 1)"
  hue="$((hash % 360))"

  # avoid unwanted ranges
  (( avoidPink )) && (( hue >= 290 && hue <= 340 )) && hue=$(( (hue + 50) % 360 ))
  (( avoidYellow )) && (( hue >= 40 && hue <= 80 )) && hue=$(( (hue + 41) % 360 ))

  # apply theme mapping (outputs hue sat)
  read -r hue sat < <(remap_hue "$hue")

  # convert HSV to RGB
  read -r red grn blu < <(hsv_to_rgb "$hue" "$sat" "$light" | gamma_correct "$(awk "BEGIN { print $light / 100 }")")

  (( debug )) && echo "hue=$hue sat=$sat rgb=$red $grn $blu"

  # output colored string
  while IFS= read -r line; do
    echo -e "\e[38;2;${red};${grn};${blu}m${line}\e[0m"
  done <<< "$string"
}

# --- Entry point ---

# parse --theme=NAME from args
if [[ "$1" == --theme=* ]]; then
  theme="${1#--theme=}"
  shift
fi

if [ -t 0 ]; then
  if [ $# -gt 0 ]; then
    colorize_string "$*"
  else
    colorize_string
    echo
  fi
else
  input="$(cat)"
  colorize_string "$input"
fi