#!/usr/bin/env bash
# hledger-bar - see below

usage() {
    cat <<'EOS'
hledger-bar - show quick bar charts in the terminal
Usage:
hledger-bar    [-h|--help]
hledger-bar    [-v|-vv] [SCALE] BALARGS
hledger bar -- [-v|-vv] [SCALE] BALARGS  # might need extra quoting

Requires bash (or osh) and hledger >= ~1.25.

With no arguments, shows this help.
Otherwise, runs hledger's 'balance' command, reporting monthly
balance changes by default, and shows the period totals as a bar chart
in the terminal, with positive amounts shown as '+' and negatives as '-'
(in green and red respectively, unless NO_COLOR is set).

Bars are not auto-sized; they will be (amount divided by SCALE) long, where
SCALE is 100 by default. This is overrideable by a numeric first argument.
Eg if bars are too long, try 200; if they are too short, try 50.

Most other options/arguments understood by the balance command can be
used, such as one or more account names, or different report intervals
like -W (weekly) or -Q (quarterly).  There are two restrictions:

- You must ensure the report is for a single commodity. So use eg
  'cur:€' or 'cur:\\$' or 'cur:\\\\$' or '-B' or '-X$ --infer-market-prices'
  as needed.

- You can't use spaces in arguments (even quoted). If needed,
  you could write '.' instead of space.

If you don't see the results you expect:

- Note that revenues appear negative and expenses positive,
  as with the balance command; to flip signs, use --invert.

- Run as 'hledger-bar' to minimise command line quoting issues.

- Use -v as first argument to also show the (unscaled, rounded) amounts.

- Use -vv as first argument to show the amounts and the balance command
  (approximately; you might need to add one level of quoting).
  Tip: remove some of this command's first options to see a more
  human-readable balance report.

- When you are reporting changes in asset/liability/equity accounts,
  you will probably want to exclude opening/closing balance transactions,
  eg with not:desc:'(opening|closing)' or not:tag:clopen if you use those.

Examples:

$ hledger-bar food                              # monthly food expenses
$ hledger-bar 1 --count food                    # monthly food posting counts
$ hledger-bar -v 1 -f $TIMELOG -D               # daily hours, with numbers
$ hledger-bar type:c not:tag:clopen cur:\\$ -W  # weekly cashflow, $ only
$ hledger-bar type:al not:tag:clopen cur:\\$    # monthly net worth change ($)
$ hledger-bar type:rx --invert cur:\\$          # monthly profit/loss ($)
$ hledger-bar type:rx --invert cur:\\$ --infer-market-prices --value=then,$
   # monthly profit/loss ($, plus anything that can be converted to $,
   # using conversion rates on transaction dates)
$ hledger-bar . cur:\\$                         # all accounts' change ($)
$ hledger bar -- . cur:\\\\$                    # as hledger subcommand

EOS
}
###############################################################################

set -e

defscale=100
negchar="-"
poschar="+"

# utils

# https://en.wikipedia.org/wiki/ANSI_escape_code#8-bit and 24-bit colors.
# Disable if stdout is not a terminal or NO_COLOR is defined.
if [[ ! -t 1 || -n ${NO_COLOR} ]]; then
    red=''
    green=''
    nocol=''
else
    red='\e[38;5;1m'
    green="\e[38;5;2m"
    nocol="\e[0m"
fi

unquote() { s="${1%\"}"; echo "${s#\"}"; }

# process command line
shownum=0
verbose=0
scale=${defscale}
if [[ $# -eq 0 || $1 == --help || $1 == -h ]]; then usage; exit; fi
if [[ $1 == -v ]]; then shownum=1; shift; elif [[ $1 == -vv ]]; then shownum=1; verbose=1; shift; fi
if [[ $1 =~ ^[0-9]+$ ]]; then scale=$1; shift; fi

# helpers

# The hledger reporting command. It should produce a two-column CSV
# report with one line per period and one currency.  It must have a
# report interval for --transpose to work.  shellcheck disable=SC2124
cmd="hledger balance -Ocsv --transpose -N -0 --layout=bare -M $*"

printcmd() {
    echo "From command (might need added quotes):"  # don't know how to print all the slashes
    echo "${cmd}"
}

printamterr() {
    cat <<EOS
Error: could not parse as a single-commodity amount: $1
The report must be restricted or converted to a single commodity.
Eg to report $, try: cur:\\\\$ or cur:\\\\\\\\$ or -B or -X$ --infer-market-prices
EOS
    printcmd
}

# main
# shellcheck disable=SC2312
${cmd} | while IFS=, read -r period amount; do
    if [[ ! ${amount} =~ [0-9] ]]; then continue; fi  # ignore lines where amount has no digits
    if [[ ${amount} =~ , ]]; then printamterr "${amount}"; exit 1; fi  # check there is a single amount column
    shopt -s inherit_errexit
    int=$(printf '%.f' "$(unquote "${amount}")")
    if [[ ${shownum} -gt 0 ]]; then num=$(printf "%10d " "${int}"); else num=""; fi
    if [[ ${int} -lt 0 ]]; then c="${negchar}"; col=${red}; else c="${poschar}"; col=${green}; fi
    n=$((int / scale))
    absn=${n#-}
    bar=$(while [[ ${absn} -gt 0 ]]; do printf "%s" "${c}"; absn=$((absn - 1)); done)
    printf '%s\t%b%s%s%b\n' "$(unquote "${period}")" "${col}" "${num}" "${bar}" "${nocol}"
done

if [[ ${verbose} -gt 0 ]]; then printcmd; fi