#!/bin/sh

# Color diff output, for human consumption

# License: LGPLv2
# Author:
#    http://www.pixelbeat.org/
# Notes:
#    If 2 parameters are passed, then they are passed to
#    the `diff -Naru` command first. Otherwise the parameters
#    (or stdin) are assumed to be diff format and are colourised.
#
#    VIM can be useful for viewing diffs also:
#      diff -Naru a b | vim -R -
#      vim -R a-b.diff
# Changes:
#    V0.1, 12 Feb 2008, Initial release
#    V0.2, 18 Feb 2008, Use tput rather than hardcoding escape sequences.
#    V0.3, 24 Apr 2008, Support Mac OS X
#    V0.4, 30 Apr 2008, P@draigBrady.com
#                         Use $PAGER if set
#                       Manfred Schwarb <manfred99@gmx.ch>
#                         Support `diff -c` format fully.
#                         Pointed out issues with less -EF options.
#                         Suggested to use the less -S option.
#    V0.5, 18 Jun 2009, P@draigBrady.com
#                         Delineate each file level item with highlight.
#                         Simplify expressions by using '&' in replacement.
#                         Use 't' after all matches for consistency and speed.

# less -K reportedly not available on older Mac OS X
less -K -Ff /dev/null !2 >/dev/null && global CTRL_C_EXITS := '"-K'"

global RED := '1'; global GREEN := '2'; global BLUE := '4'; global BRIGHT := ''1;''

proc tputc {
    global bright := $1; global colour := $2
    test $bright && tput bold
    tput setaf $colour
}

global DEL := $[tputc $BRIGHT $RED]
global ADD := $[tputc $BRIGHT $GREEN]
global CHG := $[tputc $BRIGHT $BLUE]
global FIL := $[tput smso] #highlight file level items
global RST := $[tput sgr0]

if test "$Argc" -eq "2" {
    diff -Naru @Argv
} else {
    cat @Argv
} |
sed "
s/^\*\{3\}.*\*\{4\}/$CHG&$RST/;t
  s/^-\{3\}.*-\{4\}/$CHG&$RST/;t
             s/^@.*/$CHG&$RST/;t
         s/^[0-9].*/$CHG&$RST/;t
             s/^!.*/$CHG&$RST/;t

             s/^-.*/$DEL&$RST/;t
             s/^<.*/$DEL&$RST/;t

            s/^\*.*/$ADD&$RST/;t
            s/^\+.*/$ADD&$RST/;t
             s/^>.*/$ADD&$RST/;t

       s/^Only in.*/$FIL&$RST/;t
       s/^Index: .*/$FIL&$RST/;t
         s/^diff .*/$FIL&$RST/;t
" |
$(PAGER:-less -QRS $CTRL_C_EXITS)

# could use less -EFX also, but for large files or lots of scrolling, this
# is a lot more obtrusive on the terminal as the [de]init codes not used.
(CommandList
  children: [
    (AndOr
      children: [
        (SimpleCommand
          words: [{(less)} {(-K)} {(-Ff)} {(/dev/null)}]
          redirects: [(Redir op_id:Redir_Great fd:2 arg_word:{(/dev/null)} spids:[95])]
        )
        (Assignment
          keyword: Assign_None
          pairs: [(assign_pair lhs:(LhsName name:CTRL_C_EXITS) op:Equal rhs:{(DQ (-K))} spids:[100])]
          spids: [100]
        )
      ]
      op_id: Op_DAmp
    )
    (Sentence
      child: 
        (Assignment
          keyword: Assign_None
          pairs: [(assign_pair lhs:(LhsName name:RED) op:Equal rhs:{(1)} spids:[106])]
          spids: [106]
        )
      terminator: <Op_Semi ";">
    )
    (Sentence
      child: 
        (Assignment
          keyword: Assign_None
          pairs: [(assign_pair lhs:(LhsName name:GREEN) op:Equal rhs:{(2)} spids:[110])]
          spids: [110]
        )
      terminator: <Op_Semi ";">
    )
    (Sentence
      child: 
        (Assignment
          keyword: Assign_None
          pairs: [(assign_pair lhs:(LhsName name:BLUE) op:Equal rhs:{(4)} spids:[114])]
          spids: [114]
        )
      terminator: <Op_Semi ";">
    )
    (Assignment
      keyword: Assign_None
      pairs: [(assign_pair lhs:(LhsName name:BRIGHT) op:Equal rhs:{(SQ <"1;">)} spids:[118])]
      spids: [118]
    )
    (FuncDef
      name: tputc
      body: 
        (BraceGroup
          children: [
            (Sentence
              child: 
                (Assignment
                  keyword: Assign_None
                  pairs: [
                    (assign_pair
                      lhs: (LhsName name:bright)
                      op: Equal
                      rhs: {($ VSub_Number "$1")}
                      spids: [131]
                    )
                  ]
                  spids: [131]
                )
              terminator: <Op_Semi ";">
            )
            (Assignment
              keyword: Assign_None
              pairs: [
                (assign_pair
                  lhs: (LhsName name:colour)
                  op: Equal
                  rhs: {($ VSub_Number "$2")}
                  spids: [135]
                )
              ]
              spids: [135]
            )
            (AndOr
              children: [
                (C {(Lit_Other "[")} {(DQ ($ VSub_Name "$bright"))} {(Lit_Other "]")})
                (C {(tput)} {(bold)})
              ]
              op_id: Op_DAmp
            )
            (C {(tput)} {(setaf)} {($ VSub_Name "$colour")})
          ]
          spids: [128]
        )
      spids: [124 127]
    )
    (Assignment
      keyword: Assign_None
      pairs: [
        (assign_pair
          lhs: (LhsName name:DEL)
          op: Equal
          rhs: 
            {
              (DQ 
                (CommandSubPart
                  command_list: 
                    (CommandList
                      children: [(C {(tputc)} {($ VSub_Name "$BRIGHT")} {($ VSub_Name "$RED")})]
                    )
                  left_token: <Left_Backtick "`">
                  spids: [165 171]
                )
              )
            }
          spids: [163]
        )
      ]
      spids: [163]
    )
    (Assignment
      keyword: Assign_None
      pairs: [
        (assign_pair
          lhs: (LhsName name:ADD)
          op: Equal
          rhs: 
            {
              (DQ 
                (CommandSubPart
                  command_list: 
                    (CommandList
                      children: [(C {(tputc)} {($ VSub_Name "$BRIGHT")} {($ VSub_Name "$GREEN")})]
                    )
                  left_token: <Left_Backtick "`">
                  spids: [176 182]
                )
              )
            }
          spids: [174]
        )
      ]
      spids: [174]
    )
    (Assignment
      keyword: Assign_None
      pairs: [
        (assign_pair
          lhs: (LhsName name:CHG)
          op: Equal
          rhs: 
            {
              (DQ 
                (CommandSubPart
                  command_list: 
                    (CommandList
                      children: [(C {(tputc)} {($ VSub_Name "$BRIGHT")} {($ VSub_Name "$BLUE")})]
                    )
                  left_token: <Left_Backtick "`">
                  spids: [187 193]
                )
              )
            }
          spids: [185]
        )
      ]
      spids: [185]
    )
    (Assignment
      keyword: Assign_None
      pairs: [
        (assign_pair
          lhs: (LhsName name:FIL)
          op: Equal
          rhs: 
            {
              (DQ 
                (CommandSubPart
                  command_list: (CommandList children:[(C {(tput)} {(smso)})])
                  left_token: <Left_Backtick "`">
                  spids: [198 202]
                )
              )
            }
          spids: [196]
        )
      ]
      spids: [196]
    )
    (Assignment
      keyword: Assign_None
      pairs: [
        (assign_pair
          lhs: (LhsName name:RST)
          op: Equal
          rhs: 
            {
              (DQ 
                (CommandSubPart
                  command_list: (CommandList children:[(C {(tput)} {(sgr0)})])
                  left_token: <Left_Backtick "`">
                  spids: [210 214]
                )
              )
            }
          spids: [208]
        )
      ]
      spids: [208]
    )
    (Pipeline
      children: [
        (If
          arms: [
            (if_arm
              cond: [
                (Sentence
                  child: 
                    (C {(Lit_Other "[")} {(DQ ($ VSub_Pound "$#"))} {(-eq)} {(DQ (2))} {(Lit_Other "]")})
                  terminator: <Op_Semi ";">
                )
              ]
              action: [(C {(diff)} {(-Naru)} {(DQ ($ VSub_At "$@"))})]
              spids: [-1 235]
            )
          ]
          else_action: [(C {(cat)} {(DQ ($ VSub_At "$@"))})]
          spids: [246 255]
        )
        (C {(sed)} 
          {
            (DQ ("\n") ("s/^") (EscapedLiteralPart token:<Lit_EscapedChar "\\*">) 
              (EscapedLiteralPart token:<Lit_EscapedChar "\\{">) (3) (EscapedLiteralPart token:<Lit_EscapedChar "\\}">) (".*") 
              (EscapedLiteralPart token:<Lit_EscapedChar "\\*">) (EscapedLiteralPart token:<Lit_EscapedChar "\\{">) (4) 
              (EscapedLiteralPart token:<Lit_EscapedChar "\\}">) (/) ($ VSub_Name "$CHG") ("&") ($ VSub_Name "$RST") ("/;t\n") ("  s/^-") 
              (EscapedLiteralPart token:<Lit_EscapedChar "\\{">) (3) (EscapedLiteralPart token:<Lit_EscapedChar "\\}">) (".*-") 
              (EscapedLiteralPart token:<Lit_EscapedChar "\\{">) (4) (EscapedLiteralPart token:<Lit_EscapedChar "\\}">) (/) ($ VSub_Name "$CHG") ("&") ($ VSub_Name "$RST") 
              ("/;t\n") ("             s/^@.*/") ($ VSub_Name "$CHG") ("&") ($ VSub_Name "$RST") ("/;t\n") 
              ("         s/^[0-9].*/") ($ VSub_Name "$CHG") ("&") ($ VSub_Name "$RST") ("/;t\n") ("             s/^!.*/") ($ VSub_Name "$CHG") 
              ("&") ($ VSub_Name "$RST") ("/;t\n") ("\n") ("             s/^-.*/") ($ VSub_Name "$DEL") ("&") 
              ($ VSub_Name "$RST") ("/;t\n") ("             s/^<.*/") ($ VSub_Name "$DEL") ("&") ($ VSub_Name "$RST") ("/;t\n") ("\n") 
              ("            s/^") (EscapedLiteralPart token:<Lit_EscapedChar "\\*">) (".*/") ($ VSub_Name "$ADD") ("&") 
              ($ VSub_Name "$RST") ("/;t\n") ("            s/^") (EscapedLiteralPart token:<Lit_EscapedChar "\\+">) (".*/") 
              ($ VSub_Name "$ADD") ("&") ($ VSub_Name "$RST") ("/;t\n") ("             s/^>.*/") ($ VSub_Name "$ADD") ("&") 
              ($ VSub_Name "$RST") ("/;t\n") ("\n") ("       s/^Only in.*/") ($ VSub_Name "$FIL") ("&") ($ VSub_Name "$RST") ("/;t\n") 
              ("       s/^Index: .*/") ($ VSub_Name "$FIL") ("&") ($ VSub_Name "$RST") ("/;t\n") ("         s/^diff .*/") ($ VSub_Name "$FIL") 
              ("&") ($ VSub_Name "$RST") ("/;t\n")
            )
          }
        )
        (C 
          {
            (BracedVarSub
              token: <VSub_Name PAGER>
              suffix_op: 
                (StringUnary
                  op_id: VTest_ColonHyphen
                  arg_word: {("less -QRS ") ($ VSub_Name "$CTRL_C_EXITS")}
                )
              spids: [357 362]
            )
          }
        )
      ]
      negated: False
    )
  ]
)