#!/bin/bash
#
# punchclock - a KISS utility to track time with minimal effort
#
# Copyright 2023 Jan Koppe <post@jankoppe.de>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

set -euo pipefail

LOGFILE="${XDG_DATA_HOME:-$HOME/.local/share}/punchclock/log"
VERBOSE=0
FORMAT_SECONDS=0

# Function to print usage instructions
function usage {
  echo ""
  echo "Usage: $0 [-s|--seconds] [-l|--logfile path] [-v|--verbose] command"
  echo ""
  echo "A KISS utility to track time with minimal effort."
  echo ""
  echo "Options:"
  echo "  -s, --seconds    Output times in seconds."
  echo "  -l, --logfile    Use the logfile at this location."
  echo "  -v, --verbose    Give verbose output about what's happening."
  echo ""
  echo "Commands:"
  echo "    status         Show the last saved tracking status, start or stop."
  echo "    statusbar      Shows a symbol for tracking status and todays sum. For use in statusbars."
  echo "    start          Start tracking."
  echo "    stop           Stop tracking."
  echo "    sum            Sum of time tracked today."
  echo "    toggle         Toggle tracking."
  exit 1
}

function init {
  [[ "${VERBOSE}x" == "1x" ]] && echo "verbose: Ensuring logfile directory exists."
  local LOGFILE_DIR="${LOGFILE%$(basename $LOGFILE)}"
  [[ -d "$LOGFILE_DIR" ]] || mkdir -p "${LOGFILE%$(basename $LOGFILE)}"
  [[ "${VERBOSE}x" == "1x" ]] && echo "verbose: Ensuring logfile exists."
  [[ -f "$LOGFILE" ]] || touch "$LOGFILE"
}

function _get_status {
  local STATE=$(tail -n 1 $LOGFILE | cut -d';' -f2)
  case "$STATE" in
    "start")
      echo $STATE
      ;;
    "stop")
      echo $STATE
      ;;
    *)
      _file_corrupt "unknown state: $STATE"
      ;;
  esac
}

function _set_status {
  echo "$(date -u +%Y-%m-%dT%H:%M:%S%Z);$1" >> $LOGFILE
}

function _file_corrupt {
  echo "Attention: It seems that the contents of the logfile are corrupt."
  echo "           Please check what's in there and repair it."
  echo "           reason: $1"
  exit 1
}

function _get_active_seconds_for_day {
  local INPUT="${@:-$(date -u +%Y-%m-%d)}"
  local DATE=$(date -u -d "$INPUT" +%Y-%m-%d)

  local LAST_STATE="stop"
  local EPOCH_LAST=0
  local EPOCH_TOTAL=0

  while read LINE
  do
    if [[ "$LINE" =~ ^"$DATE" ]]
    then
      # Make sure we're alternating between different states and first line is a start
      local STATE=$(echo "$LINE" | cut -d';' -f2)
      [[ "$LAST_STATE" == "$STATE" ]] && _file_corrupt "repeated state: $LINE"
      LAST_STATE=$STATE

      # extract the unix epoch timestamp for this data point
      local TIMESTAMP=$(echo "$LINE" | cut -d';' -f1)
      local EPOCH_TIMESTAMP=$(date --date="$TIMESTAMP" -u +%s)
      if [[ "$STATE" == "stop" ]]
      then
        # if we're ending an interval, calculate the interval length and sum it up
        EPOCH_INTERVAL=$(( $EPOCH_TIMESTAMP - $EPOCH_LAST ))
        EPOCH_TOTAL=$(( $EPOCH_TOTAL + $EPOCH_INTERVAL ))
      else
        # if we're not ending an interval, remember the start epoch timestamp
        EPOCH_LAST=$EPOCH_TIMESTAMP
      fi
    fi
  done < $LOGFILE

  if [[ "$LAST_STATE" == "start" ]]
  then
    # we're in an active interval still, so let's just assume that we finish right now to include the interval up until now.
    local EPOCH_TIMESTAMP=$(date -u +%s)
    EPOCH_INTERVAL=$(( $EPOCH_TIMESTAMP - $EPOCH_LAST ))
    EPOCH_TOTAL=$(( $EPOCH_TOTAL + $EPOCH_INTERVAL ))
  fi

  echo $EPOCH_TOTAL
}

function _seconds_to_hours_and_minutes {
  # intentionally does not combine hours to days - in a summary this is usually what you want.
  local HOURS=$(printf "%02d" $(( $1/(60*60) )))
  local MINUTES=$(printf "%02d" $(echo "scale=0;($1 % (60*60))/60" | bc))
  echo "$HOURS:$MINUTES"
}

function _sum_for_day {
  local SECONDS=$(_get_active_seconds_for_day $@)
  if [[ "${FORMAT_SECONDS}x" == "1x" ]]
  then
    echo "$SECONDS"
  else
    echo "$(_seconds_to_hours_and_minutes $SECONDS)"
  fi
}

function _print_sum_for_multiple_days {
  local START=$(date -u +%Y-%m-%d -d "$1")
  local DAYS=$2

  local TOTAL_SECONDS=0

  echo -e "\033[1mDATE\t\tHOURS\tTOTAL\033[0m"
  for DAY in $(seq 0 $DAYS)
  do
    local DATE=$(date -u -d "$START + $DAY days" +%Y-%m-%d)
    local SECONDS=$(_get_active_seconds_for_day $DATE)
    local TOTAL_SECONDS=$(( $TOTAL_SECONDS + $SECONDS ))
    echo -e "$DATE\t$(_seconds_to_hours_and_minutes $SECONDS)\t$(_seconds_to_hours_and_minutes $TOTAL_SECONDS)"
  done
  echo -e "\t\t\t\033[1m$(_seconds_to_hours_and_minutes $TOTAL_SECONDS)\033[0m"
}

function _sum_for_multiple_days {
  # like _print_sum_for_multiple_days, but only returns total seconds
  local START=$(date -u +%Y-%m-%d -d "$1")
  local DAYS=$2

  local TOTAL_SECONDS=0

  for DAY in $(seq 0 $DAYS)
  do
    local DATE=$(date -u -d "$START + $DAY days" +%Y-%m-%d)
    local SECONDS=$(_get_active_seconds_for_day $DATE)
    local TOTAL_SECONDS=$(( $TOTAL_SECONDS + $SECONDS ))
  done
  echo $TOTAL_SECONDS
}

function _print_sum_for_weeks {
  local YEAR=${1:-$(date -u +%Y)}
  local TOTAL_SECONDS=0

  echo -e "\033[1mDATE\t\tHOURS\tTOTAL\033[0m"
  for WEEK in {01..52}
  do
    local MONDAY_WEEKDAY="$YEAR-W$WEEK-01"
    # date does not accept ISO8601 calendar weeks as input,
    # we need to convert to regular ISO8601 %Y-%m-%d first
    local MONDAY_DATE=$(dateconv -f %Y-%m-%d $MONDAY_WEEKDAY)
    local SECONDS=$(_sum_for_multiple_days $MONDAY_DATE 6)
    local TOTAL_SECONDS=$(( $TOTAL_SECONDS + $SECONDS ))
    echo -e "$YEAR-W$WEEK\t$(_seconds_to_hours_and_minutes $SECONDS)\t$(_seconds_to_hours_and_minutes $TOTAL_SECONDS)"
  done
  echo -e "\t\t\t\033[1m$(_seconds_to_hours_and_minutes $TOTAL_SECONDS)\033[0m"
}

function _get_number_of_days_in_year {
  local YEAR=${1:-$(date -u +"%Y")}
  if [[ $(expr $YEAR % 400) -eq 0 ]] || [[ $(expr $YEAR % 100) -eq 0 ]] || [[ $(expr $YEAR % 4) -eq 0 ]]
  then
    echo 366
  else
    echo 365
  fi
}

function command_sum {
  if [[ $# -gt 0 ]]
  then
    case $1 in
      "year-weeks")
        shift
        _print_sum_for_weeks $@
        ;;
      "year-days")
        shift
        local START=${1:-$(date -u +%Y)}-01-01
        local DAYS=$(( $(_get_number_of_days_in_year $(date -u -d "$START" +%Y)) -1 ))
        _print_sum_for_multiple_days $START $DAYS
        ;;
      "month")
        shift
        local START=${1:-$(date -u +%Y-%m)}-01
        local DAYS=$(( $(date -d "$START + 1 month - 1 days" +%d) - 1 ))
        _print_sum_for_multiple_days $START $DAYS
        ;;
      "week")
        shift
        local MONDAY_WEEKDAY=${1:-$(date -u +%Y-W%V)-01}
        # date does not accept ISO8601 calendar weeks as input,
        # we need to convert to regular ISO8601 %Y-%m-%d first
        local MONDAY_DATE=$(dateconv -f %Y-%m-%d $MONDAY_WEEKDAY)
        echo ; echo -e "Summary for week \033[1m${MONDAY_WEEKDAY}\033[0m" ; echo
        _print_sum_for_multiple_days $MONDAY_DATE 6
        ;;
      "days")
        shift
        _print_sum_for_multiple_days $@
        ;;
      *)
        _sum_for_day "$@"
        ;;
    esac
  else
    _sum_for_day
  fi
}

function command_statusbar {
  local ACTIVE="$(_seconds_to_hours_and_minutes $(_get_active_seconds_for_day))"
  case "$(_get_status)" in
    "stop")
      echo "▱ $ACTIVE"
      ;;
    "start")
      echo "▰ $ACTIVE"
      ;;
  esac
}

function command_status {
  echo "status: $(_get_status)"
}

function command_start {
  [[ $(_get_status) == "start" ]] || _set_status "start"
}

function command_stop {
  [[ $(_get_status) == "stop" ]] || _set_status "stop"
}

function command_toggle {
  STATE=$(_get_status)
  case "$STATE" in
    "stop")
      _set_status "start"
      ;;
    "start")
      _set_status "stop"
      ;;
  esac
}

# Parse command line arguments
while [[ $# -gt 0 ]]; do
  case $1 in
    -v|--verbose)
      VERBOSE=1
      shift
      ;;
    -l|--logfile)
      LOGFILE=$2
      shift
      shift
      ;;
    -s|--seconds)
      FORMAT_SECONDS=1
      shift
      ;;
    -h|--help)
      usage
      shift
      ;;
    status)
      init
      command_status
      COMMAND=status
      shift
      break
      ;;
    statusbar)
      init
      command_statusbar
      COMMAND=statusbar
      shift
      break
      ;;
    start)
      init
      command_start
      COMMAND=start
      shift
      break
      ;;
    stop)
      init
      command_stop
      COMMAND=stop
      shift
      break
      ;;
    toggle)
      init
      command_toggle
      COMMAND=toggle
      shift
      break
      ;;
    sum)
      init
      shift
      command_sum $@
      COMMAND=sum
      break
      ;;
    *)
      echo "Invalid option or command: $1"
      usage
      ;;
  esac
done