#!/bin/bash
# Copyright (c) 2022, the Dart project authors.  Please see the AUTHORS file
# for details. All rights reserved. Use of this source code is governed by a
# BSD-style license that can be found in the LICENSE file.
#
# Usage: szcmp files
#
# Compare sizes of files as percentages in a table.  Column header is the
# baseline (i.e. all sizes in the column are in terms of the file in the column
# header).
#
# Example with dart2js workflow:
#
#     $ dart2js  ...  --out=v1/m.js
#     # change dart2js
#     $ dart2js  ...  --out=v2/m.js
#     # change dart2js again
#     $ dart2js  ...  --out=v3/m.js
#
#     $ szcmp v?/m.js
#                       v1/m.js  v2/m.js  v3/m.js
#     5793879  v1/m.js        =  -4.499%  +4.461%
#     6066812  v2/m.js  +4.711%        =  +9.382%
#     5546433  v3/m.js  -4.271%  -8.577%        =
#
# The first column of the matrix is usually the most relevant - `v2` is 4.7%
# larger than `v1` and `v3` is 4.2% smaller than `v1`. The other columns can be
# useful for understanding the differential changes. Sizes relative to `v2` are
# in the next column, e.g. the step from `v2` to `v3` was a reduction of
# 8.6%. Above-diagonal values show the percentage change in the 'undo'
# direction. While changing from `v2` to `v3` reduces by 8.6%, reverting that
# change would be an increase of 9.4%.

wc -c "$@" |
awk '
$2 == "total" { next; }

{
  N++
  r[N,0] = $1;
  r[N,1] = $2;
}

END {
  r[0,0] = ""  # header col 0
  r[0,1] = ""  # header col 1

  for (i = 1; i <= N; i++) { #skips "total" line
    r[0, i+1] = r[i,1]  # name header

    for (j = 1; j <= N; j++) {
      s1 = r[i,0]
      s2 = r[j,0];
      if (s1 == s2) {
        r[i, j+1] = "="
      } else {
        x = sprintf("%.3f%%", (s1 - s2) / s2 * 100)
        if (s1 > s2) x = "+" x
        r[i, j+1] = x
      }
    }
  }

  # find column widths
  for (cc = 0; cc <= N+1; cc++) {
    w[cc] = 0;
    for (rr = 0; rr <= N; rr++) {
      if (length(r[rr,cc]) > w[cc]) w[cc] = length(r[rr,cc])
    }
  }

  for (rr = 0; rr <= N; rr++) {
    line = ""
    sep = ""
    for (cc = 0; cc <= N+1; cc++) {
      line = line sep sprintf("%*s", w[cc], r[rr, cc])
      sep = "  "
    }
    print line
  }
}
'