#!/bin/sh
# This file is a part of Julia. License is MIT: https://julialang.org/license

# both $1 and $2 are absolute paths beginning with /
# returns relative path to $2/$target from $1/$source

proc relpath {
    test $Argc -ge 1 && test $Argc -le 2 || return 1
    global current := $(2:+"$1")
    global target := $(2:-"$1")
    test $target != . || global target := '/'
    global target := ""/$(target##/)""
    test $current != . || global current := '/'
    global current := $(current:="/")
    global current := ""/$(current##/)""
    global appendix := $(target##/)
    global relative := ''''
    while appendix="${target#"$current"/}"
        [ "$current" != '/' ] && [ "$appendix" = "$target" ]; {
        if test $current = $appendix {
            global relative := $(relative:-.)
            echo $(relative#/)
            return 0
        }
        global current := $(current%/*)
        global relative := ""$relative$(relative:+/)..""
    }
    global relative := ""$relative$(relative:+${appendix:+/})$(appendix#/)""
    echo $relative
}
relpath @Argv
(CommandList
  children: [
    (FuncDef
      name: relpath
      body: 
        (BraceGroup
          children: [
            (AndOr
              children: [
                (C {(Lit_Other "[")} {($ VSub_Pound "$#")} {(-ge)} {(1)} {(Lit_Other "]")})
                (AndOr
                  children: [
                    (C {(Lit_Other "[")} {($ VSub_Pound "$#")} {(-le)} {(2)} {(Lit_Other "]")})
                    (ControlFlow token:<ControlFlow_Return return> arg_word:{(1)})
                  ]
                  op_id: Op_DPipe
                )
              ]
              op_id: Op_DAmp
            )
            (Assignment
              keyword: Assign_None
              pairs: [
                (assign_pair
                  lhs: (LhsName name:current)
                  op: Equal
                  rhs: 
                    {
                      (DQ 
                        (BracedVarSub
                          token: <VSub_Number 2>
                          suffix_op: 
                            (StringUnary
                              op_id: VTest_ColonPlus
                              arg_word: {(DQ ($ VSub_Number "$1"))}
                            )
                          spids: [53 59]
                        )
                      )
                    }
                  spids: [51]
                )
              ]
              spids: [51]
            )
            (Assignment
              keyword: Assign_None
              pairs: [
                (assign_pair
                  lhs: (LhsName name:target)
                  op: Equal
                  rhs: 
                    {
                      (DQ 
                        (BracedVarSub
                          token: <VSub_Number 2>
                          suffix_op: 
                            (StringUnary
                              op_id: VTest_ColonHyphen
                              arg_word: {(DQ ($ VSub_Number "$1"))}
                            )
                          spids: [65 71]
                        )
                      )
                    }
                  spids: [63]
                )
              ]
              spids: [63]
            )
            (AndOr
              children: [
                (C {(Lit_Other "[")} {(DQ ($ VSub_Name "$target"))} {(KW_Bang "!") (Lit_Other "=")} {(.)} 
                  {(Lit_Other "]")}
                )
                (Assignment
                  keyword: Assign_None
                  pairs: [(assign_pair lhs:(LhsName name:target) op:Equal rhs:{(/)} spids:[90])]
                  spids: [90]
                )
              ]
              op_id: Op_DPipe
            )
            (Assignment
              keyword: Assign_None
              pairs: [
                (assign_pair
                  lhs: (LhsName name:target)
                  op: Equal
                  rhs: 
                    {
                      (DQ (/) 
                        (BracedVarSub
                          token: <VSub_Name target>
                          suffix_op: (StringUnary op_id:VOp1_DPound arg_word:{(Lit_Slash /)})
                          spids: [97 101]
                        )
                      )
                    }
                  spids: [94]
                )
              ]
              spids: [94]
            )
            (AndOr
              children: [
                (C {(Lit_Other "[")} {(DQ ($ VSub_Name "$current"))} {(KW_Bang "!") (Lit_Other "=")} 
                  {(.)} {(Lit_Other "]")}
                )
                (Assignment
                  keyword: Assign_None
                  pairs: [(assign_pair lhs:(LhsName name:current) op:Equal rhs:{(/)} spids:[120])]
                  spids: [120]
                )
              ]
              op_id: Op_DPipe
            )
            (Assignment
              keyword: Assign_None
              pairs: [
                (assign_pair
                  lhs: (LhsName name:current)
                  op: Equal
                  rhs: 
                    {
                      (DQ 
                        (BracedVarSub
                          token: <VSub_Name current>
                          suffix_op: (StringUnary op_id:VTest_ColonEquals arg_word:{(DQ (/))})
                          spids: [126 132]
                        )
                      )
                    }
                  spids: [124]
                )
              ]
              spids: [124]
            )
            (Assignment
              keyword: Assign_None
              pairs: [
                (assign_pair
                  lhs: (LhsName name:current)
                  op: Equal
                  rhs: 
                    {
                      (DQ (/) 
                        (BracedVarSub
                          token: <VSub_Name current>
                          suffix_op: (StringUnary op_id:VOp1_DPound arg_word:{(Lit_Slash /)})
                          spids: [139 143]
                        )
                      )
                    }
                  spids: [136]
                )
              ]
              spids: [136]
            )
            (Assignment
              keyword: Assign_None
              pairs: [
                (assign_pair
                  lhs: (LhsName name:appendix)
                  op: Equal
                  rhs: 
                    {
                      (DQ 
                        (BracedVarSub
                          token: <VSub_Name target>
                          suffix_op: (StringUnary op_id:VOp1_DPound arg_word:{(Lit_Slash /)})
                          spids: [149 153]
                        )
                      )
                    }
                  spids: [147]
                )
              ]
              spids: [147]
            )
            (Assignment
              keyword: Assign_None
              pairs: [(assign_pair lhs:(LhsName name:relative) op:Equal rhs:{(SQ )} spids:[157])]
              spids: [157]
            )
            (While
              cond: [
                (Assignment
                  keyword: Assign_None
                  pairs: [
                    (assign_pair
                      lhs: (LhsName name:appendix)
                      op: Equal
                      rhs: 
                        {
                          (DQ 
                            (BracedVarSub
                              token: <VSub_Name target>
                              suffix_op: 
                                (StringUnary
                                  op_id: VOp1_Pound
                                  arg_word: {(DQ ($ VSub_Name "$current")) (Lit_Slash /)}
                                )
                              spids: [166 173]
                            )
                          )
                        }
                      spids: [164]
                    )
                  ]
                  spids: [164]
                )
                (Sentence
                  child: 
                    (AndOr
                      children: [
                        (C {(Lit_Other "[")} {(DQ ($ VSub_Name "$current"))} 
                          {(KW_Bang "!") (Lit_Other "=")} {(SQ </>)} {(Lit_Other "]")}
                        )
                        (C {(Lit_Other "[")} {(DQ ($ VSub_Name "$appendix"))} {(Lit_Other "=")} 
                          {(DQ ($ VSub_Name "$target"))} {(Lit_Other "]")}
                        )
                      ]
                      op_id: Op_DAmp
                    )
                  terminator: <Op_Semi ";">
                )
              ]
              body: 
                (DoGroup
                  children: [
                    (If
                      arms: [
                        (if_arm
                          cond: [
                            (Sentence
                              child: 
                                (C {(Lit_Other "[")} {(DQ ($ VSub_Name "$current"))} {(Lit_Other "=")} 
                                  {(DQ ($ VSub_Name "$appendix"))} {(Lit_Other "]")}
                                )
                              terminator: <Op_Semi ";">
                            )
                          ]
                          action: [
                            (Assignment
                              keyword: Assign_None
                              pairs: [
                                (assign_pair
                                  lhs: (LhsName name:relative)
                                  op: Equal
                                  rhs: 
                                    {
                                      (DQ 
                                        (BracedVarSub
                                          token: <VSub_Name relative>
                                          suffix_op: 
                                            (StringUnary
                                              op_id: VTest_ColonHyphen
                                              arg_word: {(.)}
                                            )
                                          spids: [234 238]
                                        )
                                      )
                                    }
                                  spids: [232]
                                )
                              ]
                              spids: [232]
                            )
                            (C {(echo)} 
                              {
                                (DQ 
                                  (BracedVarSub
                                    token: <VSub_Name relative>
                                    suffix_op: (StringUnary op_id:VOp1_Pound arg_word:{(Lit_Slash /)})
                                    spids: [245 249]
                                  )
                                )
                              }
                            )
                            (ControlFlow
                              token: <ControlFlow_Return return>
                              arg_word: {(0)}
                            )
                          ]
                          spids: [-1 229]
                        )
                      ]
                      spids: [-1 258]
                    )
                    (Assignment
                      keyword: Assign_None
                      pairs: [
                        (assign_pair
                          lhs: (LhsName name:current)
                          op: Equal
                          rhs: 
                            {
                              (DQ 
                                (BracedVarSub
                                  token: <VSub_Name current>
                                  suffix_op: 
                                    (StringUnary
                                      op_id: VOp1_Percent
                                      arg_word: {(Lit_Slash /) ("*")}
                                    )
                                  spids: [263 268]
                                )
                              )
                            }
                          spids: [261]
                        )
                      ]
                      spids: [261]
                    )
                    (Assignment
                      keyword: Assign_None
                      pairs: [
                        (assign_pair
                          lhs: (LhsName name:relative)
                          op: Equal
                          rhs: 
                            {
                              (DQ ($ VSub_Name "$relative") 
                                (BracedVarSub
                                  token: <VSub_Name relative>
                                  suffix_op: 
                                    (StringUnary
                                      op_id: VTest_ColonPlus
                                      arg_word: {(Lit_Slash /)}
                                    )
                                  spids: [275 279]
                                ) (..)
                              )
                            }
                          spids: [272]
                        )
                      ]
                      spids: [272]
                    )
                  ]
                  spids: [209 284]
                )
            )
            (Assignment
              keyword: Assign_None
              pairs: [
                (assign_pair
                  lhs: (LhsName name:relative)
                  op: Equal
                  rhs: 
                    {
                      (DQ ($ VSub_Name "$relative") 
                        (BracedVarSub
                          token: <VSub_Name relative>
                          suffix_op: 
                            (StringUnary
                              op_id: VTest_ColonPlus
                              arg_word: 
                                {
                                  (BracedVarSub
                                    token: <VSub_Name appendix>
                                    suffix_op: 
                                      (StringUnary
                                        op_id: VTest_ColonPlus
                                        arg_word: {(Lit_Slash /)}
                                      )
                                    spids: [293 297]
                                  )
                                }
                            )
                          spids: [290 298]
                        ) 
                        (BracedVarSub
                          token: <VSub_Name appendix>
                          suffix_op: (StringUnary op_id:VOp1_Pound arg_word:{(Lit_Slash /)})
                          spids: [299 303]
                        )
                      )
                    }
                  spids: [287]
                )
              ]
              spids: [287]
            )
            (C {(echo)} {(DQ ($ VSub_Name "$relative"))})
          ]
          spids: [19]
        )
      spids: [14 18]
    )
    (C {(relpath)} {(DQ ($ VSub_At "$@"))})
  ]
)