import struct Swiftz.List

/// Cycles a finite list of numbers into an infinite list.
let finite : List<UInt> = [1, 2, 3, 4, 5]
let infiniteCycle = finite.cycle()

/// Lists also support the standard map, filter, and reduce operators.
let l : List<Int> = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

let twoToEleven = l.map(+1) // [2, 3, 4, 5, 6, 7, 8, 9, 10, 11]
let even = l.filter((==0) • (%2)) // [2, 4, 6, 8, 10]
let sum = l.reduce(curry(+), initial: 0) // 55

/// Plus a few more.
let partialSums = l.scanl(curry(+), initial: 0) // [0, 1, 3, 6, 10, 15, 21, 28, 36, 45, 55]
let firstHalf = l.take(5) // [1, 2, 3, 4, 5]
let lastHalf = l.drop(5) // [6, 7, 8, 9, 10]

import protocol Swiftz.JSONDecode
import struct Swiftz.JSONKeypath
    
public class User : JSONDecodable {
    typealias J = User
    let name : String
    let age : Int
    let tweets : [String]
    let attr : String
    
    public init(_ n : String, _ a : Int, _ t : [String], _ r : String) {
        name = n
        age = a
        tweets = t
        attr = r
    }
    
    // JSON
    public class func create(x : String) -> Int -> ([String] -> String -> User) {
        return { y in { z in { User(x, y, z, $0) } } }
    }
    
    public class func fromJSON(x : JSONValue) -> User? {
        return User.create
			<^> x <? "name" 
			<*> x <? "age"
			<*> x <? "tweets" 
			<*> x <? "attrs" <> "one" // A nested keypath
    }
    
    // lens example
    public class func luserName() -> Lens<User, User, String, String> {
        return Lens { user in IxStore(user.name) { User($0, user.age, user.tweets, user.attr) } }
    }
}

public func ==(lhs : User, rhs : User) -> Bool {
    return lhs.name == rhs.name && lhs.age == rhs.age && lhs.tweets == rhs.tweets && lhs.attr == rhs.attr
}

let userjs = "{\"name\": \"max\", \"age\": 10, \"tweets\": [\"hello\"], \"attrs\": {\"one\": \"1\"}}"

/// The JSON we've decoded works perfectly with the User structure we defined above.  In case it didn't,
/// the user would be nil.
let user : User? = JSONValue.decode(userjs) >>- User.fromJSON // .Some( User("max", 10, ["hello"], "1") )

import struct Swiftz.Lens
import struct Swiftz.IxStore

/// A party has a host, who is a user.
final class Party {
    let host : User

    init(h : User) {
        host = h
    }

    class func lpartyHost() -> Lens<Party, Party, User, User> {
        let getter = { (party : Party) -> User in
            party.host
        }

        let setter = { (party : Party, host : User) -> Party in
            Party(h: host)
        }

        return Lens(get: getter, set: setter)
    }
}

/// A Lens for the User's name.
extension User {
    public class func luserName() -> Lens<User, User, String, String> {
        return Lens { user in IxStore(user.name) { User($0, user.age, user.tweets, user.attrs) } }
    }
}

/// Let's throw a party now.
let party = Party(h: User("max", 1, [], Dictionary()))

/// A lens for a party host's name.
let hostnameLens = Party.lpartyHost() • User.luserName()

/// Retrieve our gracious host's name.
let name = hostnameLens.get(party) // "max"

/// Our party seems to be lacking in proper nouns. 
let updatedParty = (Party.lpartyHost() • User.luserName()).set(party, "Max")
let properName = hostnameLens.get(updatedParty) // "Max"

let xs = [1, 2, 0, 3, 4]

import protocol Swiftz.Semigroup
import func Swiftz.sconcat
import struct Swiftz.Min

/// The least element of a list can be had with the Min Semigroup.
let smallestElement = sconcat(Min(2), xs.map { Min($0) }).value() // 0

import protocol Swiftz.Monoid
import func Swiftz.mconcat
import struct Swiftz.Sum

/// Or the sum of a list with the Sum Monoid.
let sum = mconcat(xs.map { Sum($0) }).value() // 10

import struct Swiftz.Product

/// Or the product of a list with the Product Monoid.
let product = mconcat(xs.map { Product($0) }).value() // 0

import struct Swiftz.Function
import struct Swiftz.Either

/// An Arrow is a function just like any other.  Only this time around we
/// can treat them like a full algebraic structure and introduce a number
/// of operators to augment them.
let comp = Function.arr(+3) • Function.arr(*6) • Function.arr(/2)
let both = comp.apply(10) // 33

/// An Arrow that runs both operations on its input and combines both
/// results into a tuple.
let add5AndMultiply2 = Function.arr(+5) &&& Function.arr(*2)
let both = add5AndMultiply2.apply(10) // (15, 20)

/// Produces an Arrow that chooses a particular function to apply
/// when presented with the side of an Either.
let divideLeftMultiplyRight = Function.arr(/2) ||| Function.arr(*2)
let left = divideLeftMultiplyRight.apply(Either.left(4)) // 2
let right = divideLeftMultiplyRight.apply(Either.right(7)) // 14

import class Swiftz.Chan

/// A Channel is an unbounded FIFO stream of values with special semantics
/// for reads and writes.
let chan : Chan<Int> = Chan()

/// All writes to the Channel always succeed.  The Channel now contains `1`.
chan.write(1) // happens immediately

/// Reads to non-empty Channels occur immediately.  The Channel is now empty.
let x1 = chan.read()

/// But if we read from an empty Channel the read blocks until we write to the Channel again.
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 1 * Double(NSEC_PER_SEC)), dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), {
    chan.write(2) // Causes the read to suceed and unblocks the reading thread.
})

let x2 = chan.read() // Blocks until the dispatch block is executed and the Channel becomes non-empty.