pending.nvim/lua/pending/parse.lua

local config = require('pending.config')

---@class pending.parse
local M = {}

---@param s string
---@return boolean
local function is_valid_date(s)
  local y, m, d = s:match('^(%d%d%d%d)-(%d%d)-(%d%d)$')
  if not y then
    return false
  end
  local yn = tonumber(y) --[[@as integer]]
  local mn = tonumber(m) --[[@as integer]]
  local dn = tonumber(d) --[[@as integer]]
  if mn < 1 or mn > 12 then
    return false
  end
  if dn < 1 or dn > 31 then
    return false
  end
  local t = os.time({ year = yn, month = mn, day = dn })
  local check = os.date('*t', t) --[[@as osdate]]
  return check.year == yn and check.month == mn and check.day == dn
end

---@return string
local function date_key()
  return config.get().date_syntax or 'due'
end

local weekday_map = {
  sun = 1,
  mon = 2,
  tue = 3,
  wed = 4,
  thu = 5,
  fri = 6,
  sat = 7,
}

local month_map = {
  jan = 1, feb = 2, mar = 3, apr = 4,
  may = 5, jun = 6, jul = 7, aug = 8,
  sep = 9, oct = 10, nov = 11, dec = 12,
}

---@param today osdate
---@return string
local function today_str(today)
  return os.date('%Y-%m-%d', os.time({ year = today.year, month = today.month, day = today.day })) --[[@as string]]
end

---@param text string
---@return string|nil
function M.resolve_date(text)
  local lower = text:lower()
  local today = os.date('*t') --[[@as osdate]]

  if lower == 'today' or lower == 'eod' then
    return today_str(today)
  end

  if lower == 'yesterday' then
    return os.date(
      '%Y-%m-%d',
      os.time({ year = today.year, month = today.month, day = today.day - 1 })
    ) --[[@as string]]
  end

  if lower == 'tomorrow' then
    return os.date(
      '%Y-%m-%d',
      os.time({ year = today.year, month = today.month, day = today.day + 1 })
    ) --[[@as string]]
  end

  if lower == 'sow' then
    local delta = -((today.wday - 2) % 7)
    return os.date(
      '%Y-%m-%d',
      os.time({ year = today.year, month = today.month, day = today.day + delta })
    ) --[[@as string]]
  end

  if lower == 'eow' then
    local delta = (1 - today.wday) % 7
    return os.date(
      '%Y-%m-%d',
      os.time({ year = today.year, month = today.month, day = today.day + delta })
    ) --[[@as string]]
  end

  if lower == 'som' then
    return os.date(
      '%Y-%m-%d',
      os.time({ year = today.year, month = today.month, day = 1 })
    ) --[[@as string]]
  end

  if lower == 'eom' then
    return os.date(
      '%Y-%m-%d',
      os.time({ year = today.year, month = today.month + 1, day = 0 })
    ) --[[@as string]]
  end

  if lower == 'soq' then
    local q = math.ceil(today.month / 3)
    local first_month = (q - 1) * 3 + 1
    return os.date(
      '%Y-%m-%d',
      os.time({ year = today.year, month = first_month, day = 1 })
    ) --[[@as string]]
  end

  if lower == 'eoq' then
    local q = math.ceil(today.month / 3)
    local last_month = q * 3
    return os.date(
      '%Y-%m-%d',
      os.time({ year = today.year, month = last_month + 1, day = 0 })
    ) --[[@as string]]
  end

  if lower == 'soy' then
    return os.date(
      '%Y-%m-%d',
      os.time({ year = today.year, month = 1, day = 1 })
    ) --[[@as string]]
  end

  if lower == 'eoy' then
    return os.date(
      '%Y-%m-%d',
      os.time({ year = today.year, month = 12, day = 31 })
    ) --[[@as string]]
  end

  if lower == 'later' or lower == 'someday' then
    return config.get().someday_date
  end

  local n = lower:match('^%+(%d+)d$')
  if n then
    return os.date(
      '%Y-%m-%d',
      os.time({
        year = today.year,
        month = today.month,
        day = today.day + (tonumber(n) --[[@as integer]]),
      })
    ) --[[@as string]]
  end

  n = lower:match('^%+(%d+)w$')
  if n then
    return os.date(
      '%Y-%m-%d',
      os.time({
        year = today.year,
        month = today.month,
        day = today.day + (tonumber(n) --[[@as integer]]) * 7,
      })
    ) --[[@as string]]
  end

  n = lower:match('^%+(%d+)m$')
  if n then
    return os.date(
      '%Y-%m-%d',
      os.time({
        year = today.year,
        month = today.month + (tonumber(n) --[[@as integer]]),
        day = today.day,
      })
    ) --[[@as string]]
  end

  n = lower:match('^%-(%d+)d$')
  if n then
    return os.date(
      '%Y-%m-%d',
      os.time({
        year = today.year,
        month = today.month,
        day = today.day - (tonumber(n) --[[@as integer]]),
      })
    ) --[[@as string]]
  end

  n = lower:match('^%-(%d+)w$')
  if n then
    return os.date(
      '%Y-%m-%d',
      os.time({
        year = today.year,
        month = today.month,
        day = today.day - (tonumber(n) --[[@as integer]]) * 7,
      })
    ) --[[@as string]]
  end

  local ord = lower:match('^(%d+)[snrt][tdh]$')
  if ord then
    local day_num = tonumber(ord) --[[@as integer]]
    if day_num >= 1 and day_num <= 31 then
      local m, y = today.month, today.year
      if today.day >= day_num then
        m = m + 1
        if m > 12 then
          m = 1
          y = y + 1
        end
      end
      local t = os.time({ year = y, month = m, day = day_num })
      local check = os.date('*t', t) --[[@as osdate]]
      if check.day == day_num then
        return os.date('%Y-%m-%d', t) --[[@as string]]
      end
      m = m + 1
      if m > 12 then
        m = 1
        y = y + 1
      end
      t = os.time({ year = y, month = m, day = day_num })
      check = os.date('*t', t) --[[@as osdate]]
      if check.day == day_num then
        return os.date('%Y-%m-%d', t) --[[@as string]]
      end
      return nil
    end
  end

  local target_month = month_map[lower]
  if target_month then
    local y = today.year
    if today.month >= target_month then
      y = y + 1
    end
    return os.date(
      '%Y-%m-%d',
      os.time({ year = y, month = target_month, day = 1 })
    ) --[[@as string]]
  end

  local target_wday = weekday_map[lower]
  if target_wday then
    local current_wday = today.wday
    local delta = (target_wday - current_wday) % 7
    return os.date(
      '%Y-%m-%d',
      os.time({ year = today.year, month = today.month, day = today.day + delta })
    ) --[[@as string]]
  end

  return nil
end

---@param text string
---@return string description
---@return { due?: string, cat?: string } metadata
function M.body(text)
  local tokens = {}
  for token in text:gmatch('%S+') do
    table.insert(tokens, token)
  end

  local metadata = {}
  local i = #tokens
  local dk = date_key()
  local date_pattern_strict = '^' .. vim.pesc(dk) .. ':(%d%d%d%d%-%d%d%-%d%d)$'
  local date_pattern_any = '^' .. vim.pesc(dk) .. ':(.+)$'

  while i >= 1 do
    local token = tokens[i]
    local due_val = token:match(date_pattern_strict)
    if due_val then
      if metadata.due then
        break
      end
      if not is_valid_date(due_val) then
        break
      end
      metadata.due = due_val
      i = i - 1
    else
      local raw_val = token:match(date_pattern_any)
      if raw_val then
        if metadata.due then
          break
        end
        local resolved = M.resolve_date(raw_val)
        if not resolved then
          break
        end
        metadata.due = resolved
        i = i - 1
      else
        local cat_val = token:match('^cat:(%S+)$')
        if cat_val then
          if metadata.cat then
            break
          end
          metadata.cat = cat_val
          i = i - 1
        else
          break
        end
      end
    end
  end

  local desc_tokens = {}
  for j = 1, i do
    table.insert(desc_tokens, tokens[j])
  end
  local description = table.concat(desc_tokens, ' ')

  return description, metadata
end

---@param text string
---@return string description
---@return { due?: string, cat?: string } metadata
function M.command_add(text)
  local cat_prefix = text:match('^(%S.-):%s')
  if cat_prefix then
    local first_char = cat_prefix:sub(1, 1)
    if first_char == first_char:upper() and first_char ~= first_char:lower() then
      local rest = text:sub(#cat_prefix + 2):match('^%s*(.+)$')
      if rest then
        local desc, meta = M.body(rest)
        meta.cat = meta.cat or cat_prefix
        return desc, meta
      end
    end
  end
  return M.body(text)
end

return M