AST.hs

-- | AST for conditional restrictions and incomplete AST for opening hours.
module ConditionalRestriction.Parse.AST
  ( Token,
    ConditionalRestriction (..),
    Expression (..),
    Condition (..),
    ComparisonOp (..),
    OpeningHours (..),
    OHState,
    RuleType (..),
    RuleSequence (..),
    WeekdaySelector,
    TimeSelector,
    SelectorSequence (..),
    WeekdayRange (..),
    TimeSpan (..),
  )
where

import Data.Hourglass (TimeOfDay, WeekDay)

-- | A single token. Is used to represent values of any kind that the parser does not touch.
type Token = String

-- | AST representation of a conditional restriction.
newtype ConditionalRestriction = ConditionalRestriction [Expression]
  deriving (Eq, Show)

-- | AST representation of a conditional restriction expression, containing a value and conditions for that value
data Expression
  = Expression
      Token
      -- ^ The value
      [Condition]
      -- ^ The conditions. All conditions must be met when evaluating.
  deriving (Eq, Show)

-- | AST representation of a condition.
data Condition
  = -- | An 'OpeningHours' condition. When evaluating, the given time must be within those opening hours.
    OH OpeningHours
  | -- | A comparison. Looks something like @"weight > 3.0"@
    Comparison Token ComparisonOp Double
  | -- | An absolute condition, e.g. @"wet"@, @"disabled"@.
    Absolute Token
  deriving (Eq, Show)

-- | A comparison operator.
data ComparisonOp = Gt | Lt | GtEq | LtEq | Eq
  deriving (Eq, Show)

-- | AST representation of opening hours. Not complete.
newtype OpeningHours = OpeningHours [RuleSequence]
  deriving (Eq, Show)

-- | Opening hour state. True\/False if known to be open/closed, Nothing if unknown.
type OHState = Maybe Bool

-- | Type of opening hour rule.
data RuleType
  = -- | First rule or rules separated by ";".
    Normal
  | -- | Rules separated by ",".
    Additional
  deriving (Eq, Show)

-- | AST representation of a rule sequence.
data RuleSequence = RuleSequence RuleType SelectorSequence OHState
  deriving (Eq, Show)

-- | AST representation of a weekday selector (e.g. @"Sa-Di, Th"@).
type WeekdaySelector = [WeekdayRange]

-- | AST representation of a time selector (e.g. @"18:00-20:00, 21:00-03:00"@).
type TimeSelector = [TimeSpan]

-- | AST representation of a selector sequence (e.g. @"24/7"@, @"We-Su 18:00-20:00"@).
data SelectorSequence
  = TwentyFourSeven
  | WeekdaySel WeekdaySelector
  | TimeSel TimeSelector
  | WeekdayTime WeekdaySelector TimeSelector
  deriving (Eq, Show)

-- | AST representation of a weekday range.
data WeekdayRange
  = SingleDay WeekDay
  | WdayRange WeekDay WeekDay
  deriving (Eq, Show)

-- | AST representation of time span.
data TimeSpan
  = Moment TimeOfDay
  | Span TimeOfDay TimeOfDay
  deriving (Eq, Show)