#!/bin/sh

# change any uppercase letters in file and directory
# names in the current directory and below.

# License: LGPLv2

# note filenames with \1 or \n will cause problems

# note this is still much slower than it could be,
# as there is a separate mv executed for each file/dir.
# It would be much more efficient to pass the output
# of this to a python script for e.g. that does the rename

find -depth '(' -type f -o -type d ')' |
env LC_ALL=C grep -E "/[^/]*[A-Z]+[^/]*$" | #only process upcase names
sed -e '
{
    #escape any chars that could cause problems
    #s/\([]"{}\$]\)/\\\1/g

    #keep orig path in hold space
    h

    #put basename in pattern space
    s/.*\/\([^/]*$\)/\1
/

    #lowercase basename
    y/ABCDEFGHIJKLMNOPQRSTUVWXYZ/abcdefghijklmnopqrstuvwxyz/

    #exchange pattern and hold space
    x

    #format mv args 1
    s/\(.*\/\)\([^/]*$\)/\1\2
\1/

    #format mv args 2
    G
}' |

tr -d '\n'   |    #format mv args 3
tr '
' '\0' |    #format mv args 4
xargs -r0 -n2 mv  #execute mv
(CommandList
  children: [
    (Pipeline
      children: [
        (C {(find)} {(-depth)} {(EscapedLiteralPart token:<Lit_EscapedChar "\\(">)} {(-type)} {(f)} {(-o)} 
          {(-type)} {(d)} {(EscapedLiteralPart token:<Lit_EscapedChar "\\)">)}
        )
        (SimpleCommand
          words: [{(grep)} {(-E)} {(DQ ("/[^/]*[A-Z]+[^/]*") (Lit_Other "$"))}]
          more_env: [(env_pair name:LC_ALL val:{(C)} spids:[52])]
        )
        (C {(sed)} {(-e)} 
          {
            (SQ <"\n"> <"{\n"> <"    #escape any chars that could cause problems\n"> 
              <"    #s/\\([]\"{}\\$]\\)/\\\\\\1/g\n"> <"\n"> <"    #keep orig path in hold space\n"> <"    h\n"> <"\n"> 
              <"    #put basename in pattern space\n"> <"    s/.*\\/\\([^/]*$\\)/\\1\u0001/\n"> <"\n"> <"    #lowercase basename\n"> 
              <"    y/ABCDEFGHIJKLMNOPQRSTUVWXYZ/abcdefghijklmnopqrstuvwxyz/\n"> <"\n"> <"    #exchange pattern and hold space\n"> <"    x\n"> <"\n"> <"    #format mv args 1\n"> 
              <"    s/\\(.*\\/\\)\\([^/]*$\\)/\\1\\2\u0001\\1/\n"> <"\n"> <"    #format mv args 2\n"> <"    G\n"> <"}">
            )
          }
        )
        (C {(tr)} {(-d)} {(SQ <"\\n">)})
        (C {(tr)} {(SQ <"\u0001">)} {(SQ <"\\0">)})
        (C {(xargs)} {(-r0)} {(-n2)} {(mv)})
      ]
      negated: False
    )
  ]
)