Automatic holidays calendar - Printable Version

Code:
local function fetch_holidays()
  local rows = db:getall('SELECT year, month, day, name, duration FROM scheduler_holidays ORDER BY year, month, day')
  if type(rows) ~= 'table' or #rows == 0 then
    log('holiday monitor: scheduler_holidays table is empty or not accessible')
    return {}
  end

  local entries = {}
  for _, row in ipairs(rows) do
    local year = tonumber(row.year)
    local month = tonumber(row.month)
    local day = tonumber(row.day)
    local name = row.name or 'Holiday'
    local duration = tonumber(row.duration) or 1
    if year and month and day then
      table.insert(entries, {
        year = year,
        month = month,
        day = day,
        name = name,
        duration = duration,
      })
    end
  end
  return entries
end

local function build_periods(entries)
  local periods = {}
  for _, entry in ipairs(entries) do
    local start_ts = os.time({ year = entry.year, month = entry.month, day = entry.day, hour = 12 })
    local end_ts = start_ts + (entry.duration - 1) * 24 * 60 * 60
    table.insert(periods, {
      name = entry.name,
      start_ts = start_ts,
      end_ts = end_ts,
      start_year = entry.year,
      start_month = entry.month,
      start_day = entry.day,
      end_year = os.date('*t', end_ts).year,
      end_month = os.date('*t', end_ts).month,
      end_day = os.date('*t', end_ts).day,
      duration = entry.duration,
    })
  end
  table.sort(periods, function(a, b)
    return a.start_ts < b.start_ts
  end)
  return periods
end

local entries = fetch_holidays()
if #entries == 0 then
  log('holiday monitor: no scheduled holidays found in database')
  return
end

local periods = build_periods(entries)
if #periods == 0 then
  log('holiday monitor: could not build holiday periods')
  return
end

local today = os.date('*t')
local today_ts = os.time({ year = today.year, month = today.month, day = today.day, hour = 12 })
local yesterday_ts = today_ts - 24 * 60 * 60

local candidate = nil
for _, period in ipairs(periods) do
  if period.end_ts == yesterday_ts then
    candidate = period
    break
  end
end

if candidate then
  log(string.format(
    'Today is the first working day after scheduled non-working period "%s" from %04d-%02d-%02d to %04d-%02d-%02d lasting %d day(s)',
    candidate.name,
    candidate.start_year, candidate.start_month, candidate.start_day,
    candidate.end_year, candidate.end_month, candidate.end_day,
    candidate.duration
  ))
else
  log('holiday monitor: no scheduled non-working period ended yesterday')
end