import std/[times, os, strutils, strbasics, strscans, sets, re, tables], parseopt

const VERSION = "0.1"
const configDir = expandTilde("~/.config/then/")
const defaultConfigFile = configDir & "then.toml"
const defaultCalendarFile = configDir & "calendar.then"

type
  Token = object
    token: string
    precedence: int

# Creates a default configuration file if it doesn't exist
proc createDefaultConfigFile() =
  if not fileExists(defaultConfigFile):
    if not dirExists(configDir):
      createDir(configDir)
    writeFile(defaultConfigFile, """
    [config]
    directory = "~/.config/then/"
    """)

# Creates a default calendar file if it doesn't exist
proc createDefaultCalendarFile() =
  if not fileExists(defaultCalendarFile):
    if not dirExists(configDir):
      createDir(configDir)
    writeFile(defaultCalendarFile, """
    # Add your events here
    """)

proc printHelp(badCmd: string) =
  if badCmd != "":
    echo badCmd & " is not a valid option\n"
  echo """
Usage:
  then [options] [commands]

OPTIONS
  -h, --help     show list of CLI options
  -v, --version  show then version
  --future=DAYS  set future
  --past=DAYS    set past

COMMANDS
  a              print upcoming agenda (default command)
  e              open default calendar file in $EDITOR
  j              print the modified julian day
  """
  quit()

proc printVersion() =
  echo "then " & VERSION
  quit()

proc checkType(c: string): string =
  var cond = c
  if cond[0] == '!':
    cond.delete(0..0)
  if find(cond, re"^\d{4}$") > -1: return "year"
  if find(cond, re"^\d{1,2}$") > -1: return "day"
  if cond in DefaultLocale.MMM.toHashSet or cond in DefaultLocale.MMMM.toHashSet: return "month"
  if cond in DefaultLocale.ddd.toHashSet or cond in DefaultLocale.dddd.toHashSet: return "dayofweek"
  if find(cond, re"\d{1,2}:\d{2}") > -1: return "time"
  if find(cond, re"\dw") > -1: return "firstweek"
  if find(cond, re"\dl") > -1: return "lastweek"
  if find(cond, re"J%\d([-+]\d)?") > -1: return "julian"
  return "unknown"

proc checkCond(cond: string, day: DateTime): bool =
  case checkType(cond):
    of "year":
      if parseInt(cond) == day.year: return true
    of "day":
      if parseInt(cond) == parseInt(day.format("d")): return true
      if parseInt(cond) == parseInt(day.format("dd")): return true
    of "month":
      if cond == day.format("MMM"): return true
      if cond == day.format("MMMM"): return true
    of "dayofweek":
      if cond == day.format("ddd"): return true
      if cond == day.format("dddd"): return true
    of "time":
      return true
    of "firstweek":
      discard
# Uh oh we didn't think about this hard enough

    of "unknown":
      echo "UNKNOWN THING ", cond
  return false

# Splits a string on whitespace, but maintains whitespace in date groups
proc splitWhitespaceExceptParens(str:string): seq[string] =
  var result: seq[string] = newSeq[string]()
  var inParens = false
  for token in str.splitWhitespace:
    if token.contains(')'): inParens = false
    if inParens:
      result.add(result.pop & ' ' & token)
    else:
      result.add(token)
    if token.contains('('): inParens = true
  return result

proc parseDateToTable(date:string): Table[string,seq[string]] =
  var table = initTable[string,seq[string]]()
  let conditions = splitWhitespaceExceptParens(date)
  for c in conditions:
    let condType = checkType(c)
    if not table.hasKey(condType):
      table[condType] = @[]
    table[condType].add(c)
  return table


proc getEvents(cal: seq[string], day: DateTime): seq[string] =
  var events: seq[string] = newSeq[string]()
  for line in cal:
    var (success, date, event) = scanTuple(line, "$*,$*")
    if success:
      date.strip
      event.strip
      let conditions  = parseDateToTable(date)
      echo conditions
      var match = true
      #for c in conditions:
      #  var cond = c.toLower.capitalizeAscii
      #  if checkCond(cond, day) == false:
      #    match = false
      #    break
      #if match:
      #  events.add(event)
      #  break
    else:
      echo "WARNING: Cannot parse line: ", line
  return events

proc printEvents(cal: seq[string], day: DateTime) =
  let events = getEvents(cal, day)
  if events.len > 0:
    echo day.format("ddd  yyyy MMM dd")
    for e in events:
      echo " - ", e

proc openCal(file: string): seq[string] =
  let f = open(file)
  var cal: seq[string]
  for line in f.lines:
    cal.add(line)
  f.close()
  return cal

proc printCalendar() =
  let cal = openCal(defaultCalendarFile)
  var past = 3
  var future = 7
  let now = now()

  while past > 0:
    let curDay = now - past.days
    printEvents(cal, curDay)
    dec past

  printEvents(cal, now)

  for i in 1..future:
    let curDay = now + i.days
    printEvents(cal, curDay)

proc main() =
  var   past: int = 1
  var future: int = 14
  var  noArg: bool = true
  for kind, key, val in getopt():
    case kind
    of cmdLongOption, cmdShortOption:
      noArg = false
      case key
      of "help", "h":
        printHelp("")
      of "version", "v":
        printVersion()
      else:
        printHelp(key)
    else:
      discard

  if noArg:
    printCalendar()

when isMainModule:
  main()